### Draft

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- 1 June 2012 

## 6 INTEGRATED HEALTH EF FECTS OF SHORT

- TERM OZONE EXPOSURE

6.1 Introduction

This chapter reviews, s ummarizes, and integrates the evidence for various health 

### 1
outcomes associated with short

- term (i.e., hours, days, or weeks) exposures to O 3 . 

### 2 Numerous controlled human exposure, epidemiologic, and toxicological studies have 

### 3 permitted evaluation of the relat ionships between short

- term O 3 exposure and a range of 

### 4 endpoints related to respiratory effects (Section 6.2 ), cardiovascular effects (Section 6.3 ), 

### 5 and mortality (Section 6.2 , Section 6.3 , and Section 6.6 ). A smaller number of studies 

### 6
were available to assess the effects of O 3 exposure on other physiological systems such as 

### 7 the central nervous system (Section 6.4 ), liver and metabolism (Section 6.5.1 ), and 

### 8 cutaneous and ocular tissues (Sec tion 6.5.2 ). This chapter evaluates the majority of recent 

### 9 (i.e., published since the completion of the 2006 O 3 AQCD) short

- term exposure studies; 

### 10
h owever, those for birth outcomes and infant mortality are evaluated in Chapter 7 

### 11 (Section 7.4 ), because they compare associations among overlapping short

- and long



### 12 term exposure windows that are difficult to distinguish. 

### 13

Within each individual section of this chapter, a brief summary of conclusions from the 

### 14
2006 O 3 AQCD is included along with an evaluation of recent evidence that is intended 

### 15 to build upon the body of evidence from previous reviews. The studies evaluated are 

### 16 organized by health endpoint (e.g., lung function, pulmonary inflammation) then by 

### 17 scientific discipline (e.g., controlled human exposure, epidemiology, and toxicology). 

### 18 Each major section (e.g., respiratory, cardiovascular, mortality) concludes with an 

### 19 integrated summary of the findings and a conclusion regarding c ausality based upon the 

### 20
framework described in the Preamble to this ISA. The causal determinations are 

### 21 presented for a broad health effect category, such as respiratory effects, with coherence 

### 22 and plausibility based on the total evidence available across d isciplines and across the 

### 23 suite of related health endpoints, including cause

- specific mortality. 

### 24



## 6.2 Respiratory Effects

Based on evidence integrated across controlled human exposure, epidemiologic, and 

### 25 toxicological studies, the 2006 O 3 AQCD concluded “that acute O 3 exposure is causally 

### 26 associated with respiratory system effects” ( U.S. EPA, 2006b ) . Contributing to this 

### 27 conclusion were the consistency and coherence across scientific disciplines for the effects 

### 28

### Draft

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- 2 June 2012 of short

- term O 3 exposure on a variety of respiratory outcomes including “pulmonary 

### 1 function decrements, respira tory symptoms, lung inflammation, and increased lung 

### 2 permeability, airway hyperresponsiveness.” Collectively, these findings provided 

### 3 biological plausibility for associations in epidemiologic studies observed between short



### 4
term increases in ambient O 3 conc entration and increases in respiratory symptoms and 

### 5 respiratory

- related hospitalizations and emergency department (ED) visits. 

### 6

Controlled human exposure studies have provided strong and quantifiable exposure



### 7 response data on the human health effects of O 3 . The most salient observations from 

### 8
studies reviewed in the 1996 and 2006 O 3 AQCDs ( U.S. EPA, 2006b
, 1996a ) included: 

### 9 (1) young healthy adults exposed to O 3 concentrations ≥ 80 ppb develop significa nt 

### 10 reversible, transient decrements in pulmonary function and symptoms of breathing 

### 11
discomfort if minute ventilation ( V ̇ E ) or duration of exposure is increased sufficiently; 

### 12 (2) relative to young adults, children experience similar spirometric responses but lower 

### 13 incidence of symptoms from O 3 exposure; (3) relative to young adults, O 3 - induced 

### 14 spirometric resp onses are decreased in older individuals; (4) there is a large degree of 

### 15 intersubject variability in physiologic and symptomatic responses to O 3, but responses 

### 16 tend to be reproducible within a given individual over a period of several months; (5) 

### 17 subjects exposed repeatedly to O 3 for several days experience an attenuation of 

### 18 spirometric and symptomatic responses on successive exposures, which is lost after about 

### 19 a week without exposure; and (6) acute O 3 exposure initiates an inflammatory response 

### 20 that may p ersist for at least 18 to 24 hours postexposure. 

### 21

Substantial evidence for biologically plausible O 3 - induced respiratory morbidity has been 

### 22 derived from the coherence between toxicological and controlled human exposure study 

### 23 findings for parallel endpoints. For example, O 3 - induced lung function decrements and 

### 24 increased airway hyperresponsiveness have been observed in both animals and humans. 

### 25 Airway hyperresponsiveness could be an important consequence of exposure to ambient 

### 26
O 3 because the airways are then predisposed to narrowing upon inhalation of a variety of 

### 27 ambient stimuli. Additional airway hyperresponsiveness tends to resolve more slowly and 

### 28 appears less subject to attenuation with repeated exposures than lung function 

### 29
de crements. Increased permeability and inflammation have been observed in the airways 

### 30
of humans and animals alike after O 3 exposure, although these processes are not 

### 31 necessarily associated with immediate changes in lung function or hyperresponsiveness. 

### 32
Furth ermore, the potential relationship between repetitive bouts of acute inflammation 

### 33 and the development of chronic respiratory disease is unknown. Another feature of 

### 34
O 3 - related respiratory morbidity is impaired host defense and reduced resistance to lung 

### 35
inf ection, which has been strongly supported by toxicological evidence and, to a limited 

### 36 extent, by evidence from controlled human exposure studies. Recurrent respiratory 

### 37 infection in early life is associated with increased incidence of asthma in humans. 

### 38

### Draft

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- 3 June 2012 In c oncordance with experimental studies, epidemiologic studies have provided clear 

### 1 evidence for decrements in lung function related to short

- term ambient O 3 exposure. 

### 2 These effects were demonstrated in healthy children attending camps, adults exercising or 

### 3

wo rking outdoors, and children with and without asthma ( U.S. EPA, 2006b
, 1996a ) . In 

### 4 addition to lung function decrements, short

- term increases in ambient O 3 concentration 

### 5 were associated with increases in respiratory symptoms (e.g., cough, wheeze, shortness of 

### 6 breath), notably in large U.S. panel studie s of children with asthma ( Gent et al., 2003 ; 

### 7 Mortimer et al., 2000 ) . The evidence across disciplines for O 3 effects on a range of 

### 8 respiratory endpoints collectively provides support for epidemiologic studies that have 

### 9
demonstrate d consistent associations between short

- term increases in ambient O 3 

### 10 concentration and increases in respiratory hospital admissions and ED visits, specifically 

### 11 during the summer or warm months. In contrast with other respiratory health endpoints, 

### 12 epidemiol ogic evidence did not clearly support a relationship between short

- term O 3 

### 13 exposure and respiratory mortality. Although O 3 was consistently associated with 

### 14 nonaccidental and cardiopulmonary mortality, the contribution of respiratory causes to 

### 15 these finding s was uncertain as the few studies that examined mortality specifically from 

### 16 respiratory causes reported inconsistent associations with ambient O 3 concentrations. 

### 17

As will be discussed throughout this section, consistent with the strong body of evidence 

### 18

pr esented in the 2006 O 3 AQCD, recent studies continue to support associations between 

### 19
short

- term O 3 exposure and respiratory effects, in particular, lung function decrements in 

### 20 controlled human exposure studies, airway inflammatory responses in toxicologica l 

### 21 studies, and respiratory

- related hospitalizations and ED visits. Recent epidemiologic 

### 22 studies contribute new evidence for potentially at

- risk populations and associations 

### 23 linking ambient O 3 concentrations with biological markers of airway inflammation an d 

### 24 oxidative stress, which is consistent with the extensive evidence from controlled human 

### 25 exposure and toxicological studies. Furthermore, extending the potential range of 

### 26
well

- established O 3 - associated respiratory effects, recent multicity studies and a 

### 27

m ulticontinent study demonstrate associations between short

- term increases in ambient 

### 28
O 3 concentration and respiratory

- related mortality. 

### 29

6.2.1 Lung Function

6.2.1.1 Controlled Human Exposure

This section focuses on studies examining O 3 effects on lung function and respiratory 

### 30 symptoms in volunteers exposed, for periods of up to 8 hours, to O 3 concentrations 

### 31 ranging from 40 to 500 ppb, while at rest or during exercise of varying intensity. 

### 32

### Draft

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- 4 June 2012 Responses to acute O 3 exposures in the range of ambient concentrations include 

### 1 decreased inspiratory capacity; mild bronchoconstriction; rapid, shallow breathing 

### 2 patterns during exercise; and symptoms of cough and pain on deep inspiration (PDI). 

### 3 Reflex inhibition of inspiration results in a decrease in forced vital capacity (FVC) an d 

### 4 total lung capacity (TLC) and, in combination with mild bronchoconstriction, contributes 

### 5 to a decrease in the forced expiratory volume in 1 second (FEV 1 ). 

### 6

In studies that have exposed subjects during exercise, the majority of shorter duration 

### 7 (≤ 4

- hour exposures) studies utilized an intermittent exercise protocol in which subjects 

### 8
rotated between 15

- minute periods of exercise and rest. A limited number of 1

- to 2

- hour 

### 9 studies, mainly focusing on exercise performance, have utilized a continuous exercise 

### 10 regime. A quasi continuous exercise protocol is common to prolonged exposure studies 

### 11 where subjects complete 50

- minute periods of exercise followed by 10

- minut e rest 

### 12 periods. 

### 13

The majority of controlled human exposure studies have been conducted within exposure 

### 14 chambers, although a smaller number of studies used a facemask to expose subjects to 

### 15
O 3 . Little effort has been made herein to differentiate between face mask and chamber 

### 16 exposures since FEV 1 and respiratory symptom responses appear minimally affected by 

### 17 these exposure modalities. Similar responses between facemask and chamber exposures 

### 18 have been reported for exposures to 80 and 120 ppb O 3 (6.6

- hour, modera te quasi 

### 19 continuous exercise, 40 L/min) and 300 ppb O 3 (2 h, heavy intermittent exercise, 70 

### 20 L/min) ( Adams, 2003a
, b
, 2002 )

. 

### 21

The majority of controlled human ex posure studies investigating the effects O 3 are of a 

### 22 randomized, controlled, crossover design in which subjects were exposed, without 

### 23 knowledge of the exposure condition and in random order to clean filtered air (FA; the 

### 24 control) and, depending on the stud y, to one or more O 3 concentrations. The FA control 

### 25 exposure provides an unbiased estimate of the effects of the experimental procedures on 

### 26 the outcome(s) of interest. Comparison of responses following this FA exposure to those 

### 27 following an O 3 exposure all ows for estimation of the effects of O 3 itself on an outcome 

### 28 measurement while controlling for independent effects of the experimental procedures. 

### 29 As individuals may experience small changes in various health endpoints from exercise, 

### 30 diurnal variation, or other effects in addition to those of O 3 during the course of an 

### 31 exposure, the term “O 3 - induced” is used herein to designate effects that have been 

### 32 corrected or adjusted for such extraneous responses as measured during FA exposures. 

### 33

Spirometry, viz., FEV 1 , is a common health endpoint used to assess effects of O 3 on 

### 34 respiratory health in controlled human exposure studies. In considering 6.6

- hour 

### 35 exposures to FA, group mean FEV 1 changes have ranged from

- 0.7% ( McDonnell et al., 

### 36
1991 ) to 2.7% ( Adam s, 2006a ) . On average, across ten 6.6

- hour exposure studies, there 

### 37

### Draft

– Do Not Cite or Quote 6

- 5 June 2012 has been a 1.0% (n = 279) increase in FEV 1 ( Kim et al., 2011 ; Schelegle et al., 2009 ; 

### 1 Adams, 2006a
, 2003a
, 2002 ; Adams and Ollison, 1997 ; Folinsbee et al., 1994 ; 

### 2 McDonnell et al., 1991 ; Horstman et al., 1990 ; Folinsbee et al., 1988 ) . Regardless of the 

### 3 reason for small changes in FEV 1 over the course of FA exposures, wheth er biologically 

### 4 based or a systematic effect of the experimental procedures, the use of FA responses as a 

### 5 control for the assessment of responses following O 3 exposure in randomized exposure 

### 6 studies serves to eliminate alternative explanations other than t hose of O 3 itself in causing 

### 7 the measured responses. 

### 8

Considering FEV 1 responses in young healthy adults, an O 3 - induced change in FEV 1 is 

### 9 typically the difference between the decrement observed with O 3 exposure and the 

### 10 improvement observed with FA exposure. Noting that some healthy individuals 

### 11 experience small improvements while others have small decrements in FEV 1 following 

### 12 FA exposure, investigators have used the randomized, crossover design with each subject 

### 13 serving as their own control (exposure to FA) to discern relatively small effects with 

### 14 certainty since alternative explanations for these effects are controlled for by the nature of 

### 15 the experimental design. The utility of intraindividual FA contro l exposures becomes 

### 16 more apparent when considering individuals with respiratory disease. The occurrence of 

### 17
exercise

- induced bronchospasm is well recognized in patients with asthma and COPD 

### 18 and may be experienced during both FA and O 3 exposures. Absent corr ection for FA 

### 19 responses, exercise

- induced changes in FEV 1 could be mistaken for responses due to O 3 . 

### 20 This biological phenomenon serves as an example to emphasize the need for a proper 

### 21 control exposure in assessing the effects of O 3 as well as the role of t his control in 

### 22 eliminating the influence of other factors on the outcomes of interest. 

### 23

Pulmonary Function Effects of Ozone Exposure in Healthy Subjects
Acute Exposure of Healthy Subjects
The majority of controlled human exposure studies have investigated the effects of 

### 24 exposure to O 3 in young healthy nonsmoking adults (18

- 35 years of age). These studies 

### 25 typically use fixed concentrations of O 3 under carefully regulated environmental 

### 26 conditions and subject activity levels. The magnitude of respiratory effec ts (decrements 

### 27 in spirometry measurements and increases in symptomatic response) in these individuals 

### 28
is a function of O 3 concentration (C), minute ventilation ( V ̇ E ), and exposure duration 

### 29 (time). Any physical activity will increase minute ventilation and t herefore the dose of 

### 30
inhaled O 3 . Dose of inhaled O 3 to the lower airways is also increased due to a shift from 

### 31 nasal to oronasal breathing with a consequential decrease in O 3 scrubbing by the upper 

### 32 airways. Thus, the intensity of physiological response fol lowing an acute exposure will 

### 33 be strongly associated with minute ventilation. 

### 34

### Draft

– Do Not Cite or Quote 6

- 6 June 2012 The product of C × V ̇ E × time is commonly used as a surrogate for O 3 dose to the 

### 1 respiratory tract in controlled human exposure studies. A large body of data regarding the 

### 2
interd ependent effects of C, V ̇ E , and time on pulmonary responses was assessed in the 

### 3
1986 and 1996 O 3 AQCDs ( U.S . EPA, 1996a
, 1986 ) . Acute responses were modeled as a 

### 4 function of total inhaled dose (C × V ̇ E × time) which was found to be a better predictor of 

### 5 response to O 3 than C, V ̇ E , or time of exposure, alone, or as a combination of any two of 

### 6 these factors. However, intake dose (C × V ̇ E × time) did not adequately capture the 

### 7 temporal dynamics of pulmonary responses in a comparison between a constant (square



### 8 wave) and a variable (tri angular) O 3 exposure (average 120 ppb O 3 ; moderate exercise, 

### 9
V ̇ E = 40 L/min; 8 hour duration) conducted by Hazucha et al. (1992 ) . Recent nonlinear 

### 10 statistical models clearly describe the temporal dynamics of FEV 1 responses as a function 

### 11 of C, V ̇ E , time, and age of the exposed subject ( McDonnell et al., 2010
, 2007 )

. 

### 12

For healthy young adults exposed at rest for 2 hours, 500 ppb is the lowest O 3 

### 13 concentration reported to produce a statistically significa nt O 3 - induced group mean FEV 1 

### 14 decrement of 6.4% (n = 10) ( Folinsbee et al., 1978 ) to 6.7% (n = 13) ( Horvath et al., 

### 15
19 79 ) . Airway resistance was not clearly affected during at

- rest exposure to these 

### 16
O 3 concentrations. For exposures of 1

- 2 hours to ≥ 120 ppb O 3 , statistically significa nt 

### 17 symptomatic responses and effects on FEV 1 are observed when V ̇ E is sufficiently 

### 18 increased by exercise ( McDonnell et al., 1999b ) . For instance, 5% of young healthy 

### 19 adults exposed to 400 ppb O 3 for 2 hours during rest experienced pain on deep 

### 20 inspiration. Respiratory symptoms were not observed at lo wer exposure concentrations 

### 21 (120

- 300 ppb) or with only 1 hour of exposure even at 400 ppb. However, when exposed 

### 22
to 120 ppb O 3 for 2 hours during light

- to

- moderate intermittent exercise ( V ̇ E of 22

- 

### 23
35 L/min), 9% of individuals experienced pain on deep insp iration, 5% experienced 

### 24 cough, and 4% experienced shortness of breath. With very heavy continuous exercise 

### 25 ( V ̇ E = 89 L/min), an O 3 - induced group mean decrement of 9.7% in FEV 1 has been reported 

### 26 for healthy young adults exposed for 1 hour to 120 ppb O 3 ( Gong et al., 1986 ) . Symptoms 

### 27 are present and decrements in forced expiratory volu mes and flows occur at 160

- 240 ppb 

### 28
O 3 following 1 hour of continuous heavy exercise ( V ̇ E ≈ 55 to 90 L/min ( Gong et al., 

### 29
1986 ; Avol et al., 1984 ; Folinsbee et al., 1984 ; Adams and Schelegle, 1983 ) and 

### 30 following 2 hours of intermittent heavy exercise ( V ̇ E ≈ 65

- 68 L/min) ( Linn et al., 1986 ; 

### 31 Kulle et al., 1985 ; McDonnell et al., 1983 ) . With heavy intermittent exercise (15

- min 

### 32 intervals of rest and exercise [ V ̇ E = 68 L /min]), symptoms of breathing discomfort and a 

### 33 group mean O 3 - induced decrement of 3.4% in FEV 1 occurred in young healthy adults 

### 34 exposed for 2 hours to 120 ppb O 3 ( McDonnell et al., 1983 )

. 1 Table 6

- 1 provides 

### 35 examples of typical exercise protocols utilized in controlled human exposures to O 3 . The 

### 36

1 In total, subjects were exposed to O 3 for 2.5 hours. Intermittent exercise periods, however, were onl y conducted for the first 2 hours of exposure and FEV 1 was determined 5 minutes after the exercise was completed.

### Draft

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- 7 June 2012 V ̇ E rates in t his table are per body surface area (BSA) which is, on average, about 1.7 m 2 

### 1
and 2.0 m 2 for young healthy adult females and males, respectively, who participated in 

### 2
controlled O 3 exposure studies. 

### 3

Table 6

- 1 A ctivity levels used in controlled exposures of healthy young adults to ozone.

Activity a,b Study Duration (hours) V ̇ E (L/min per

m 2 BSA) Heart Rate (bpm) Treadmill Speed (mph) Treadmill Grade (%) Cycle (watts)

Rest 2 4 70 n.a. n.a. n.a. Light quasi

- continuous exercise 6.6

- 7.6 15 110 3.5

- 4.4 0 42

Moderate quasi

continuous exercise 6.6 17

- 23 115

- 130 3.3

- 3.5 4

- 5 72

Heavy intermittent exercise 1

- 2 27

- 33 160 3.5

- 5 10 100

Very heavy continuous exercise 1 45 160 n.a. n.a. 260

a Based on group mean exercise specific data provided in the individual studies. On average, subjects were 23 years of age. For exercise protocols, the minute ventilation and heart rate are for the exercise periods. Quasi

- continuous exercise consists of 50 minutes of exercise p eriods followed by 10 minutes of rest. Intermittent exercise consists of alternating periods of 15 minutes of exercise and 15 minutes of rest.

b References: Horvath et al. (1979 ) for rest; Adams (2000 ) and Horstman et al. (1995 ) for light quasi

- continuous exercise, 2006a ); ( 20 02
, 2000 )
, Folinsbee et al. (1988 )
, Horstman et al. (1990 ) , and McDonnell et al. (1991 ) for moderate quasi

- continuous exercise; Kehrl et al. (1987 )
, Kreit et al. (1989 ) , and McDonnell et al. (1983 ) for heavy intermittent exercise, and Gong et al. (1986 ) for very heavy continuous exercise.

### Draft

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- 8 June 2012 A

Source: Brown et al. (2008 )

.

B

Top, panel A: All studies exposed subjects to a constant (square

- wave) concentration in a chamber, except Adams (2002 ) where a facemask w as used. All responses at and above 0.06 ppm were statistically significa nt. The McDonnell et al. (2007 ) curve illustrates the predicted FEV 1 decrement at 6.6 hours as a function of O 3 concentration for a 23 year
- old (the average age of subjects that participated in the illustrated studies). Note that this curve was not “fitted” to the plotted data. Error bars (where available) are the standard error of responses. Bottom, panel B: All studies used constant (square

- wave) exposures in a chamber unless designated as triangular (t) and/or facemask (m) exposures. All responses at and above 0.07 ppm were statistically significa nt. At 0.06 ppm, Adams (2006a ) and Kim et al. (2011 ) responses to square

- wave chamber exposures were statistically significa nt. During each hour of the exposures, subjects were engaged in moderate quasi continuous exercise (40 L/min) for 50 minutes and rest for 10 minutes. Following the third hour, subjects had an additional 35

- minute rest period for lunch. The data at 0.06, 0.08 and 0.12 ppm have been offset for illustrative purposes. Studies appearing in the figure legends: Adams (2006a ); ( 2003a
, 2002 )
, Folinsbee et al. (1988 )
, Horstman et al. (1990 )
, ( Kim et al., 2011 )
, 2007 ); ( 1991 ) , a nd Schelegle et al. (2009 )

. 

### Figure 6

- 1 Cross

- study comparison of mean ozone

- ind uced FEV 1 

### decrements following 6.6 hours of exposure to ozone. 0% 2% 4% 6% 8%

0.03 0.04 0.05 0.06 0.07 0.08 0.09Ozone-inducedFEV1decrement (%)

Ozone (ppm) Adams (2006) Adams (2003) Adams (2002) Horstman et al. (1990) Kim et al. (2011) McDonnell et al. (1991) Schelegle et al. (2009) (t)
(t)

(t,m) (m) (m)

(m)

(m)

(t) (t) (t) (t)

(t)

### Draft

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- 9 June 2012 For prolonged (6.6 hours) exposures relative to shorter exposures, significa nt pulmonary 

### 1 function responses and symptoms have been observed at lower O 3 concentrations and at a 

### 2
moderate level of exercise ( V ̇ E = 40 L/min). The 6.6

- hour experimental protocol was 

### 3 intended to simulate the performance of heavy physical labor for a full workday 

### 4 ( Folinsbee et al., 1988 ) . The results from studies using 6.6 hours of constant or square



### 5 wave exposures to between 40 and 120 ppb O 3 are illustrated in Figure 6

- 1 (A)

. 

### 6 Figure 6

- 1 (B) focuses on the range from 40 to 80 ppb and includes triangular exposure 

### 7 protocols as well as facemask exposures. Exposure to 40 ppb O 3 for 6 .6 hours produces 

### 8 small, statistically non significa nt changes in FEV 1 that are relatively similar to responses 

### 9 from FA exposure ( Adams, 2002 ) . Volunteers exposed to 60 ppb O 3 experience group 

### 10

mea n O 3 - induced FEV 1 decrements of about 3% ( Kim et al., 2011 ; Brown et al., 2008 ; 

### 11 Adams, 2006a ) 1 ; those exposed to 80 ppb have group mean decrements that range from 6 

### 12
to 8% ( Adams, 2006a
, 2003a ; McDonnell et al., 1991 ; Horstman et al., 1990 ) ; at 100 ppb, 

### 13 group mean decrements range from 8 to 14% ( McDonnell et al., 1991 ; Horstman et al., 

### 14
1990 ) ; and at 120 ppb, group mean decrements of 13 to 16% are observed ( Adams, 2002 ; 

### 15 Horstman et al., 1990 ; Folinsbee et al., 1988 ) . As illustrated in Figure 6

- 1 , there is a 

### 16
smooth intake dose

- response curve without evidence of a threshold for exposures 

### 17
between 40 and 120 ppb O 3 . This is consistent with Hazucha and Lefohn (2007 ) , who 

### 18 suggested that a randomly selected group of healthy individuals of sufficient size would 

### 19 include hypo

- , normo

- , and hyper

- responsive individuals such that the average response 

### 20
would show no threshold for any spirometric endpoint. Taken together, these data 

### 21
indicate that mean FEV 1 is clearly decreased by 6.6

- hour exposures to 60 ppb O 3 and 

### 22 higher concentrations in subjects performing moderate exercise. 

### 23

The time course of responses during prolonged (6.6 ho urs) square

- wave O 3 exposures 

### 24 with moderate exercise ( V ̇ E = 40 L/min) depends on O 3 concentration. At 120 ppb O 3 , 

### 25 Folinsbee et al. (1988 ) observed that s omewhat small FEV 1 decrements and symptoms of 

### 26 breathing discomfort become apparent in healthy subjects following the second hour of 

### 27 exposure with a more rapid change in responses between the 3rd and 5th hour of 

### 28 exposure and a diminishing response or platea u in responses over the last hour of 

### 29 exposure. Relative to FA, the change in FEV 1 at 120 ppb O 3 became statistically 

### 30 significa nt after 4.6 hours. Following the same exposure protocol, Horstman et al. (1990 ) 

### 31
observed a linear increase in FEV 1 responses with time following 2 hours of exposure to 

### 32
120 ppb O 3 that was statistically different from FA responses after 3 h. At 100 ppb O 3 , 

### 33
FEV 1 responses diverged from FA after 3 hours and were statistically different at 4.6 

### 34
hours ( Horstman et al., 1990 ) . At 80 ppb O 3 , FE V 1 responses diverged from FA after 4.6 

### 35

1 Adams (2006b ) di d not find effects on FEV 1 at 60 ppb to be sta tistically significant. In an analysis of the Adams (200 6b ) data, even after removal of potential outliers, Brown et al. (2008 ) found the average effect on FEV 1 at 60 ppb to be small, but highly statistically significant (p < 0.002) using several common statistical tests.

### Draft

– Do Not Cite or Quote 6

- 10 June 2012 hours and were statistically different from FA at 5.6 hours ( Horstman et al., 1990 )

. 

### 1 Subsequently, Adams (2006a ) observed FEV 1 decrements and total respira tory symptoms 

### 2
at 80 ppb O 3 to diverge from FA responses after 3 h, but did not become statistically 

### 3
different until 6.6 hours. At 60 ppb O 3 , FEV 1 responses generally tracked responses in FA 

### 4 for the first 4.6 hours of exposure and diverged after 5.6 hours ( Adams, 2006a ) . FEV 1 

### 5 responses, but not symptomatic responses, become statistically different between 60 ppb 

### 6
O 3 and FA at 6.6 hours ( Kim et al., 2011 ; Brown et al., 2008 ) . At 40 ppb, FEV 1 and 

### 7 symptomat ic responses track FA for 5.6 hours of exposure and may begin to diverge after 

### 8
6.6 hours ( Adams, 2002 ) . In prolonged (6.6 hours) square

- wave O 3 exposures between 40 

### 9
and 120 ppb with moderate exer cise ( V ̇ E = 40 L/min), the time required for group mean 

### 10 responses to differ between O 3 and FA exposures increases with decreasing O 3 

### 11
concentration. 

### 12

As opposed to constant (i.e., square

- wave) concentration patterns used in the studies 

### 13 described above, many studies conducted at the levels of 40

- 80 ppb have used variable 

### 14
O 3 concentration patterns. It has been suggested that a triangular (variable concentration) 

### 15 exposure profile can potentially lead to higher FEV 1 responses than square

- wave profiles 

### 16 despite hav ing the same average O 3 concentration over the exposure period. Hazucha et 

### 17 al. (1992 ) were the first to investigate the effects of variable versus constant 

### 18 concentration exposures on responsiveness to O 3 . In their study, volunteers were 

### 19 randomly exposed to a triangular concentration profile (averaging 120 ppb over the 

### 20
8

- hour exposure) that increased linearly from 0

- 240 ppb for the first 4 hours of the 8

- hour 

### 21 exposure, then decreased linearly from 240 to 0 ppb over the next 4 hours of the 8

- hour 

### 22 exposure, and to an square

- wave exposure of 120 ppb O 3 for 8 hours. While the total 

### 23
inhaled O 3 doses at 4 hours and 8 hours for the square

- wave and the triangular 

### 24 concentration profile were almost identical, the FEV 1 responses were dissimilar. For the 

### 25

square

- wave exposure, FEV 1 declined ~5% by the fifth hour and then remained at that 

### 26
level. With th e triangular O 3 profile, there was minimal FEV 1 response over the first 

### 27
3 hours followed by a rapid decrease in FEV 1 to a decrement of 10.3% over the next 3 

### 28 hours. During the seventh and eighth hours, mean FEV 1 decrement improved to 6.3% as 

### 29
the O 3 concentr ation decreased from 120 to 0 ppb (mean = 60 ppb). These findings 

### 30 illustrate that the severity of symptoms and the magnitude of spirometric responses are 

### 31
time

- dependent functions of O 3 delivery rate with periods of both effect development and 

### 32 recovery duri ng the course of an exposure. 

### 33

Subsequently, others have also demonstrated that variable concentration exposures can 

### 34 elicit greater FEV 1 and symptomatic responses than do square

- wave exposures ( Adams, 

### 35
2006a
, b
, 2003a )

. Adams (2006b ) reproduced the findings of Hazucha et al. (1992 ) at 

### 36
120 ppb. However, Adams (2006a ); ( 2003a ) found that responses from an 80 ppb O 3 

### 37 (average) triangular exposure did not differ signific a ntly from those observed in the 

### 38

### Draft

– Do Not Cite or Quote 6

- 11 June 2012 80 ppb O 3 square

- wave exposure at 6.6 hours. Nevertheless, FEV 1 and symptoms were 

### 1 significa ntly different from pre

- exposure at 4.6 hours (when the O 3 concentration was 

### 2
150 ppb) in the triangular exposure, but not until 6.6 hours in the square

- wave exposure. 

### 3
At the lower O 3 concentration of 60 ppb, no temporal pattern differences in FEV 1 

### 4 responses between square

- wave and triangular exposure profiles could be discerned 

### 5 ( Adam s, 2006a ) . However, both total symptom scores and pain on deep inspiration 

### 6 tended to be greater following the 60 ppb triangular than the 60 ppb square

- wave 

### 7 exposure. At 80 ppb, respiratory symptoms tended to increase more rapidly during the 

### 8 triangular t han square

- wave exposure protocol, but then decreased during the last hour of 

### 9 exposure to be less than that observed with the square

- wave exposure at 6.6 hours. Both 

### 10 total symptom scores and pain on deep inspiration were significa ntly increased following 

### 11

e xposures to 80 ppb relative to all other exposure protocols, i.e., FA, 40, and 60 ppb 

### 12 exposures. Following the 6.6

- hour exposures, respiratory symptoms at 80 ppb were 

### 13 roughly 2

- 3 times greater than those observed at 60 ppb. At 40 ppb, triangular and 

### 14

square

- wave patterns produced spirometric and subjective symptom responses similar to 

### 15 FA exposure ( Adams, 2006a
, 2002 )

. 

### 16

For O 3 exposures of 60 ppb and greater, studies ( Adams, 2006a
, b
, 2003a ; Hazucha et al., 

### 17
1992 ) demonstrate that du ring triangular exposure protocols, volunteers exposed during 

### 18 moderate exercise ( V ̇ E = 40 L/min) may develop greater spirometric and/or symptomatic 

### 19 responses during and following peak O 3 concentrations as compared to responses over 

### 20
the same time interval of square

- wave exposures. This observation is not unexpected 

### 21 since the inhaled dose rate during peaks of the triangular protocols approached twice that 

### 22 of the square

- wave protocols, e.g., 150 ppb versus 80 ppb peak concentration. At time 

### 23
intervals toward the end of an exposure, O 3 delivery rates for the triangular protocols 

### 24 were less than those of square

- wave. At these later time intervals, there is some recovery 

### 25 of responses during triangular exposure protocols, whereas there is a continued 

### 26 development of or a plateau of responses in the square

- wave exposure protocols. Thus, 

### 27 responses during triangular protocols relative to square

- wave protocols may be expected 

### 28 to diverge and be greater following peak exposures and then converge toward the end of 

### 29

an exposure. Subsequent discussion will focus on exposures between 40 and 80 ppb 

### 30
where FEV 1 pre

- to

- post responses are similar (although not identical) between triangular 

### 31 and square

- wave protocols having equivalent average exposure concentrations. 

### 32

Schelegle et al. (2009 ) recently investigated the effects of 6.6

- hour variable O 3 exposure 

### 33 protocols at mean concentrations of 60, 70, 80, and 87 pp b on respiratory symptoms and 

### 34 pulmonary function in young healthy adults (16 F, 15 M; 21.4 ± 0.6 years) exposed 

### 35 during moderate quasi continuous exercise ( V ̇ E = 40 L/min). The mean FEV 1 (± standard 

### 36 error) decrements at 6.6 hours (end of exposure relative to pre

- exposure) were

- 

### 37
0.80 ± 0.90%, 2.72 ± 1.48%, 5.34 ± 1.42%, 7.02 ± 1.60%, and 11.42 ± 2.20% for 

### 38

### Draft

– Do Not Cite or Quote 6

- 12 June 2012 exposure to FA, 60, 70, 80, and 87 ppb O 3 , respectively. Statistically significa nt 

### 1
decrements in FEV 1 and increases in total subjective symptom scores (p <0. 05) were 

### 2 found following exposure to mean concentrations of 70, 80, and 87 ppb O 3 relative to FA. 

### 3 Statistically significa nt effects were not found at 60 ppb. One of the expressed purposes 

### 4
of the Schelegle et al. (2009 ) study was to determine the minimal mean O 3 concentration 

### 5 that produces a statistically significa nt decrement in FEV 1 and respiratory symptoms in 

### 6
hea lthy individuals completing 6.6

- hour exposure protocols. At 70 ppb, Schelegle et al. 

### 7 (2009 ) observed a statistically significa n t O 3 - induced FEV 1 decrement of 6.1% at 

### 8
6.6 hours and a significa nt increase in total subjective symptoms at 5.6 and 6.6 hours. A 

### 9

re analysis found the FEV 1 responses at 70 ppb to be significa ntly different from FA 

### 10 responses beginning at 4.6 hours of exposu re ( Lefohn et al., 2010a ) . At 60 ppb, an 

### 11
O 3 - induced 3.5% FEV 1 decrement was not found to be statistically significa nt. However, 

### 12
this effect is simi lar in magnitude to the 2.9% FEV 1 decrement at 60 ppb observed by 

### 13 Adams (2006a ) , which was found to be statistically significa nt by Brown et al. (2008 )

. 

### 14

More recently, Kim et al. (2011 ) investigated the effects of a 6.6

- hour exposure to 60 ppb 

### 15
O 3 during moderate quasi continuous exercise ( V ̇ E = 40 L/min) on pulmonary function 

### 16 and respiratory symptoms in young healthy adults (32 F, 27 M; 25.0 ± 0.5 year) who 

### 17 were roughly half GSTM1

- null an d half GSTM1

- positive. Sputum neutrophil levels were 

### 18 also measured in a subset of the subjects (13 F, 11 M). The mean FEV 1 (± standard error) 

### 19 decrements at 6.6 hours (end of exposure relative to pre

- exposure) were significa ntly 

### 20 different (p = 0.008) betwee n the FA (0.002 ± 0.46%) and O 3 (1.76 ± 0.50%) exposures. 

### 21 The inflammatory response following O 3 exposure was also significa ntly (p <0.001) 

### 22 increased relative to the FA exposure. Respiratory symptoms were not affected by O 3 

### 23 exposure. There was also no sign ifica nt effect of GSTM1 genotype on FEV 1 or 

### 24 inflammatory responses to O 3 . 

### 25

Consideration of the minimal O 3 concentration producing statistically significa nt effects 

### 26
on FEV 1 and respiratory symptoms (e.g., cough and pain on deep inspiration) following 

### 27
6.6

- ho ur exposures warrants additional discussion. As discussed above, numerous studies 

### 28 have demonstrated statistically significa nt O 3 - induced group mean FEV 1 decrements of 

### 29
6

- 8% and an increase in respiratory symptoms at 80 ppb. Schelegle et al. (2009 ) have 

### 30 now reported a statistically significa nt O 3 - induced group mean FEV 1 decrement of 6%, as 

### 31 well as increased respiratory symptoms, at 70 ppb. At 60 ppb, there is information 

### 32 available from 4 separate studies ( Kim et al., 2011 ; Schelegle et al., 2009 ; Adams, 2006a
, 

### 33

### Draft

– Do Not Cite or Quote 6

- 13 June 2012 2002 )

. 1 The group mean O 3 - induced FEV 1 decrements observed in these studies were 

### 1 3.6% (facemask, square

- wave) by Adams (2006a ); ( 2002 ) 2 , 2.8% (triangular exposure) 

### 2 and 2.9% (square

- wave exposure) by Adams (2006a ) , 3.5% (triangular exposure) by 

### 3 Schelegle et al. (2009 ) , and 1.8% (square

- wave exp osure) by Kim et al. (2011 ) . Based on 

### 4 data from these studies, at 60 ppb, the weighted

- average group mean O 3 - induced FEV 1 

### 5 decrement (i.e., adjusted for FA responses) is 2.7% (n = 150). Although not consistently 

### 6 statistically significa nt, these group mean changes in FEV 1 at 60 ppb are consistent 

### 7 among studies, i.e., none observed an average improvement in lung function follow ing a 

### 8
6.6

- hour exposure to 60 ppb O 3 . Indeed, as was illustrated in Figure 6

- 1 , the group mean 

### 9
FEV 1 responses at 60 ppb fall on a smooth intake dose

- r esponse curve for exposures 

### 10
between 40 and 120 ppb O 3 . Furthermore, in a re

- analysis of the 60 ppb square

- wave data 

### 11
from Adams (2006a )
, Brown et al. (2008 ) found the mean effects on FEV 1 to be highly 

### 12 statistically significa nt (p <0.002) using several common st atistical tests even after 

### 13 removal of 3 potential outliers. A statistically significa nt increase in total respiratory 

### 14 symptoms at 60 ppb has only been reported by Adams (2006a ) for a tri angular exposure 

### 15 protocol at 5.6 hours and 6.6 hours relative to baseline (not FA). Although not 

### 16 statistically significa nt, there was a tendency for an increase in total symptoms and pain 

### 17 on deep inspiration following the 60 ppb exposures (triangular and s quare

- wave) relative 

### 18 to those following both FA and 40 ppb exposures. The time

- course and magnitude of 

### 19
FEV 1 responses at 40 ppb resemble those occurring during FA exposures ( Adams, 2006a
, 

### 20
2002 ) . In both of these studies, there was a tendency (not statistically significa nt) for a 

### 21
small increase in total symptoms and pain on deep inspiration following the 40 ppb 

### 22 exposures relative to those following FA. Taken together, the available evidence shows 

### 23
that detectable effects of O 3 on group mean FEV 1 persist down to 60 ppb, but not 40 ppb 

### 24 in young healthy adults exposed for 6.6 hours during moderate exercise. Although group 

### 25
mean FEV 1 responses at 60 ppb are relatively small (2

- 3% mean FEV 1 decrement), it 

### 26 should be emphasized that there is considerable intersubject variability, with some 

### 27 responsive individu als consistently experiencing larger than average FEV 1 responses. 

### 28

In addition to overt effects of O 3 exposure on the large airways indicated by spirometric 

### 29 responses, O 3 exposure also affects the function of the small airways and parenchymal 

### 30 lung. Fos ter et al. (1997 ); ( 1993 ) exam ined the effect of O 3 on ventilation distribution. In 

### 31 healthy adult males (n = 6; 26.7 ± 7 years old) exposed to O 3 (330 ppb with light 

### 32 intermittent exercise for 2 h), there was a significa nt reduction in ventilation to the lower 

### 33

1 Ada ms (2006a ); ( 2002 ) both provide data for an additional group of 30 healthy subjects that were exposed via facemask to 60 ppb (square

- wave) O 3 for 6.6 hours with moderate exercise ( V ̇ E = 23 L/min per m 2 BSA). These subjects are described on page 133 of Adams (2006a ) and pages 747 and 761 of Adams (2002 ) . The FEV 1 decrement may be somewhat increased due to a target
V ̇ E of 23 L/min per m 2 BSA relative to other studies with which it is listed having the target V ̇ E of 20 L/min per m 2 BSA. Based on Adams (2003a
, b
, 2002 ) the facemask exposure is not expect to affect the FEV 1 responses relative to a chamber exposure.

2 This group average FEV 1 respons e is for a set of subjects exposed via facemask to 60 ppb O 3 , see page 133 of Adams (2006a )

.

### Draft

– Do Not Cite or Quote 6

- 14 June 2012 lung (31% of lung volume) and significa nt increases in ventilation to the upper

- and 

### 1
middle

- lung regions ( Foster et al., 1993 ) . In a subsequent study of healthy males (n = 15; 

### 2
25.4 ± 2 years old) exposed to O 3 (350 ppb with moderate intermittent exercise for 2.2 h), 

### 3
O 3 exposure caused a delayed gas washout in addition to a 14% FEV 1 decrement ( Foster 

### 4 et al., 1997 ) . The pronounced slow phase of gas washout following O 3 exposure 

### 5 represented a 24% decrease in the washout rate. A day following O 3 exposure, 50% of 

### 6 the subjects still had (or developed) a delay ed washout relative to the pre

- O 3 maneuver. 

### 7 These studies suggest a prolonged O 3 effect on the small airways and ventilation 

### 8 distribution in healthy young individuals. 

### 9

There is a rapid recovery of O 3 - induced spirometric responses and symptoms; 40 to 65% 

### 10

re covery appears to occur within about 2 hours following exposure ( Folinsbee and 

### 11 Hazucha, 1989 ) . For example, following a 2

- hour exposure to 400 ppb O 3 with 

### 12 intermittent exercise, Nightingale et al. (2000 ) observed a 13.5% mean decrement in 

### 13
FEV 1 . By 3 hours postexposure, however, only a 2.7% FEV 1 decrement persisted. Partial 

### 14 recovery also occurs following cessation of exercise despite continued exposure to O 3 

### 15 ( Folinsbee et al., 1977 ) and at low O 3 concentrations during exposure ( Hazucha et al., 

### 16
1992 ) . A slower recovery phase, especially after exposure to higher O 3 concentrations, 

### 17 may take at least 24 hours to complete ( Folinsbee and Hazucha, 2000 ; Folinsbee et al., 

### 18
1993 ) . Repeated daily exposure studies at higher concentrations typically show that FEV 1 

### 19 response to O 3 is enhanced on the second day of exposure. This enhance d response 

### 20 suggests a residual effect of the previous exposure, about 22 hours earlier, even though 

### 21 the pre

- exposure spirometry may be the same as on the previous day. The absence of the 

### 22 enhanced response with repeated exposure at lower O 3 concentrations m ay be the result 

### 23 of a more complete recovery or less damage to pulmonary tissues ( Folinsbee et al., 1994 )

. 

### 24

Predicted Responses in Healthy Subjects
Studies analyzing large data sets (hundreds of subjects) provide better predictive ability 

### 25 of acute changes in FEV 1 at low levels of O 3 and V ̇ E than is possible via comparisons 

### 26
between smaller studies. A few such studies described in the 2006 O 3 AQCD ( U.S. EPA, 

### 27
2006b ) analyzed FEV 1 responses in healthy young adults (18

- 35 years of age) recruited 

### 28 from the area around Chapel Hill, NC and exposed for 2 hours to O 3 concentrations of up 

### 29
to 400 ppb at rest or wit h intermittent exercise ( McDonnell et al., 1997 ; Seal et al., 1996 ; 

### 30 Seal et al., 1993 )

. McDonnell et al. (1999b ) examined changes in respiratory symptoms 

### 31
with O 3 exposure in a subse t of the Chapel Hill data. In general, these studies showed that 

### 32
FEV 1 and respiratory symptom responses increase with increasing O 3 concentration and 

### 33
V ̇ E and decrease with increasing subject age. More recent studies expand upon these 

### 34 analyses of FEV 1 respon ses to also include longer duration (up to 8 h) studies and periods 

### 35 of recovery following exposure. 

### 36

### Draft

– Do Not Cite or Quote 6

- 15 June 2012 McDonnell et al. (2007 ) provided a nonlinear empirical model for predicting group 

### 1 average FEV 1 responses as a function of O 3 concentration, exposure time, V ̇ E , and age of 

### 2 the exposed individual. The model predicts temporal dynamics of FEV 1 change in 

### 3 response to any set of O 3 exposure conditions that might reasonably be experienced in the 

### 4 ambient environment. The model substantially differs from earlier statistical models in 

### 5 that it effectively consid ers the concurrent processes of damage and repair, i.e., the model 

### 6
allows effects on FEV 1 to accumulate during exposure at the same time they are reduced 

### 7 due to the reversible nature of the effects. The model was based on response data of 

### 8 healthy, nonsmoki ng, white males (n = 541), 18

- 35 years old, from 15 studies conducted 

### 9 at the U.S. EPA Human Studies Facility in Chapel Hill, NC. 

### 10

McDonnell et al. (2010 ) tested the predictive ability of the model ( McDon nell et al., 

### 11
2007 ) against independent data (i.e., data that were not used to fit the model) of Adams 

### 12 (2006a ); ( 2006b
, 2003a
, 2002
, 2000 )
, Hazucha et al. (1992 ) , and Schelegle et al. (2009 )

. 

### 13 The model generally captured the dynamics of group average FEV 1 resp onses within 

### 14 about a one percentage point of the experimental data. Consistent with Bennett et al. 

### 15 (2007 ) , an increased body mass index (BMI) was found to be associated with enhanced 

### 16
FEV 1 responses to O 3 by McDonnell et al. (2010 ) . The BMI effect is of the same order of 

### 17 magnitude but in the opposite direction of the age effect where by FEV 1 responses 

### 18 diminish with increasing age. Although the effects of age and BMI are relatively strong, 

### 19 these characteristics account for only a small amount of the observed variability in 

### 20 individual responses. 

### 21

Alternatively, Lefohn et al. (2010a ) proposed that FEV 1 responses to O 3 exposure might 

### 22 be described by a cumulative integrated exposure index with a sigmoidal weighting 

### 23 function similar to the W126 used for predicting vegetation effects (see Section 9.5 ). The 

### 24 integrated exposure index is the sum of the hourly average O 3 concentrations times their 

### 25 respective weighing factors. Based on a limited number of stud ies, the authors assumed 

### 26 weighting factors ranged from near zero at 50 ppb up to approximately 1.0 for 

### 27 concentrations at ≥ 125 ppb. The concentrations of 60, 70 and 80 ppb correspond to the 

### 28 weights of 0.14, 0.28, and 0.50, respectively. These weighting fac tors apply only to the 

### 29 case of exposure during moderate exercise ( V ̇ E = 20 L/min per m 2 BSA ). Lefohn et al. 

### 30 (2010a ) calculated the cum ulative exposure index for the protocols used by Adams 

### 31 (2006a ); ( 2003a ) and Schelegle et al. (2009 ) . Th ey found statistically significa nt O 3 

### 32
effects after 4 hours on FEV 1 at 105 ppb

- hour based on Schelegle et al. (2009 ) and at 

### 33
235 ppb

- hour based on Adams (2006a ); ( 2003a ) . Based on this analysis, the authors 

### 34
recommended a 5

- hour accumulation period to protect against O 3 effects on lung 

### 35
function. 

### 36

### Draft

– Do Not Cite or Quote 6

- 16 June 2012 Intersubject Variability in Response of Healthy Subjects
Consideration of group mean changes is important in discerning if observed effects are 

### 1
due to O 3 exposure rather than chance alone. Inter

- individual variability in responses is, 

### 2 however, considerable and pertinent to assessing the fraction of the populatio n that might 

### 3 actually be affected during an O 3 exposure. Hackney et al. (1975 ) first recognized a wide 

### 4 range in the sensitivity of subjects to O 3 . The range in the subjects’ ages (29 to 49 years) 

### 5 and smoking status (0 to 50 pack years) in the Hackney et al. (1975 ) study are now 

### 6
understoo d to affect the spirometric and symptomatic responses to O 3 . Subsequently, 

### 7 DeLucia and Adams (1977 ) examined responses to O 3 in six healthy non

- smokers and 

### 8 found that two exhibited notably greater sensitivity to O 3 . Since that time, numerous 

### 9 studies have documented considerable variability in responsivene ss to O 3 even in subjects 

### 10 recruited to assure homogeneity in factors recognized or presumed to affect responses. 

### 11

An individual’s FEV 1 response to a 2 hour O 3 exposure is generally reproducible over 

### 12
several months and presumably reflects the intrinsic resp onsiveness of the individual to 

### 13
O 3 ( Hazucha et al., 2003 ; McDonnell et al., 1985b ) . The frequency distribution of 

### 14
individual FEV 1 responses following these relatively short exposures becomes skewed as 

### 15 the group mean response increases, with some individuals experiencing large reductions 

### 16
in FEV 1 ( Weinmann et al., 1995a ; Kulle et al., 1985 ) . For 2

- hour exposures with 

### 17 intermittent exercise causing a predicted average FEV 1 decrement of 10%, ind ividual 

### 18 decrements ranged from approximately 0 to 40% in white males aged 18

- 36 years 

### 19 ( McDonnell et al., 1997 ) . For an average FEV 1 decrement of 13%, Ultman et al. (2004 ) 

### 20 reported FEV 1 responses ranging from a 4% improvement to a 56% decrement in young 

### 21 healthy adu lts (32 M, 28 F) exposed for 1 hour to 250 ppb O 3 . One

- third of the subjects 

### 22
had FEV 1 decrements of >15%, and 7% of the subjects had decrements of >40%. The 

### 23
differences in FEV 1 responses did not appear to be explained by intersubject differences 

### 24
in the fra ction of inhaled O 3 retained in the lung ( Ultman et al., 2004 )

. 

### 25

### Draft

– Do Not Cite or Quote 6

- 17 June 2012 Note: During each hour of the exposures, subjects were engaged in moderate quasi continuous exercise (40 L/min) for 50 minute s and rest for 10 minutes. Following the third hour, subjects had an additional 35 minute rest period for lunch. Subjects were exposed to a triangular O 3 concentration profile having the average O 3 concentration provided in each panel. As average ozone concentration increased, the distribution of responses became asymmetric with a few individuals exhibiting large FEV 1 decrements. The percentage indicated in each panel is the portion of subjects having a FEV 1 decrement in excess of 10%. Source: Adapted with permission of American Thoracic Society ( Schelegle et al., 2009 )

. 

### Figure 6

- 2 Frequency distributions of FEV 1 

### decrements observed by Schelegle et al. (2009) in young healthy adults (16 F, 15 M) following 6. 6

- hour exposures to ozone or filtered air.

Consistent with the 1

- to 2

- hour studies, the distribution of individual responses 

### 1 following 6.6

- hour exposures becomes skewed with increasing exposure concentration 

### 2 and magnitude of the group mean FEV 1 response ( McDonnell, 1996 )

. Figure 6

- 2 

### 3 illustrates frequency distributions of individual FEV 1 responses observed in 31 young 

### 4 healthy adults following 6.6

- hour exposures between 0 and 80 ppb. Schelegle et al. 

### 5 (2009 ) found >10% FEV 1 decrements in 16, 19, 29, and 42% of individuals exposed for 

### 6 6.6 hours to 60, 70, 80, and 87 ppb, respectively. Just as there are differences in mean 

### 7 decrements between studies having similar exposure scenarios ( Figure 6

- 1 at 80 and 

### 8
120 ppb), there are differences in the proportion of individuals affected with >10% FEV 1 

### 9
decrements. At 80 ppb, the proportion affected with >10% FEV 1 decrements was 17% 

### 10 (n = 30) by Adams (2006a ) 1 , 26% (n = 60) by McDonnell (1996 ) , and 29%(n = 31) by 

### 11 Schelegle et al. (2009 ) . At 60 ppb, the proportion with >10% FEV 1 decrements was 20% 

### 12 (n = 30) by Adams (2002 ) 2 , 3% (n = 30) by Adams (2006a ) 1 , 16% (n = 31) by Schelegle 

### 13 et al. (2009 ) , and 5% (n = 59) by Kim et al. (2011 ) . Based on these studies, the weighted 

### 14 average proportion of individuals with >10% FEV 1 decrements is 10% following 

### 15 exposure to 60 ppb. Due to limited data within the published papers, these proportions 

### 16 were not corrected for responses to FA exposure where lung function typically improves 

### 17
in h ealthy adults. For example, uncorrected versus O 3 - induced (i.e., adjusted for response 

### 18

1 Not assessed by Adams ( 2006a ) , the proportion was provided in Figure 8

- 1B of the 2006 O 3 AQCD ( U.S. EPA, 2006b )

. 2 This information is from page 761 of Adams (2002 )

. Adams (2006a
, 2002 ) both provide data for a group of 30 healthy subjects that were exposed via facemask to 60 ppb (square

- wave) O 3 for 6.6 hours with moderate exercise ( V ̇ E = 23 L/mi n per m 2 BSA). These subjects are described on page 133 of Adams (2006a ) and pages 747 and 761 of Adams (20 02 ) . The FEV 1 decrement may be somewhat increased due to a target V ̇ E of 23 L/min per m 2 BSA relative to other studies with which it is listed having the target V ̇ E of 20 L/min per m 2 BSA. Based on Adams (200 3a
, b
, 2002 )
, similar FEV 1 responses are expected between facemask and chamber exposures.

### Draft

– Do Not Cite or Quote 6

- 18 June 2012 during FA exposure) proportions of individuals having >10% FEV 1 decrements in the 

### 1 Adams (2006a ) 1 st udy were, respectively, 3% versus 7% at 60 ppb and 17% versus 23% 

### 2
at 80 ppb. Thus, uncorrected proportions underestimate the actual fraction of healthy 

### 3
individuals affected. 

### 4

Given considerable inter

- individual variability in responses, the interpretation of 

### 5 biologically small group mean decrements requires careful consideration. Following 

### 6 prolonged 6.6

- hour exposures to an average level of 60 ppb O 3 , data available from four 

### 7 studies yield a weighted

- average group mean O 3 - induced FEV 1 decrement (i.e., adjus ted 

### 8 for FA responses) of 2.7% (n = 150) ( Kim et al., 2011 ; Schelegle et al., 2009 ; Adams, 

### 9
2006a
, 1998 ) . The data from these studies also yield a weighted

- average proportion 

### 10 (uncorrected for FA responses) of subjects with >10% FEV 1 decrements of 10% 

### 11 (n = 150) ( Kim et al., 2011 ; Schelegle et al., 2009 ; Adams, 2006a
, 1998 ) . In an individual 

### 12 with relatively “normal” lung function, with recognition o f the technical and biological 

### 13 variability in measurements, confidence can be given that within

- day changes in FEV 1 of 

### 14 ≥ 5% are clinically meaningful ( Pellegrino et al., 2005 ; ATS, 1991 ) . Here focus is given 

### 15
to individuals with >10% decrements in FEV 1 since some individuals in the Schelegle et 

### 16 al. (2009 ) study experienced 5

- 10% FEV 1 decrements following exposure to FA. A 10% 

### 17
FEV 1 decrement is also generally accepted as an abnormal response and a reasonable 

### 18
crit erion for assessing exercise

- induced bronchoconstriction ( Dryden et al., 2010 ; ATS, 

### 19
2000a ) . The data are not available in the published papers to determine the O 3 - induced 

### 20 proportion for either the Adams (1998 ) or Sche legle et al. (2009 ) studies. As already 

### 21 stated, however, this uncorrected proportion likely underestimates the actual proportion 

### 22 of healthy individuals experiencing O 3 - induced FEV 1 decrements in excess of 10%. 

### 23 Therefore, by considering uncorrected responses and those individuals having >10% 

### 24 decrements, 10% is an underestimate of the proportion of healthy individuals that are 

### 25 likely to experience clinically meaningful changes in lung function following exposure 

### 26
for 6.6 hours to 60 ppb O 3 during moderate exercise. Of the studies conducted at 60 ppb, 

### 27 only Kim et al. (2011 ) reported FEV 1 decrements at 60 ppb to be statistically significa nt. 

### 28
Ho wever, Brown et al. (2008 ) found those from Adams (2006a ) to be highly statistically 

### 29 significa nt. Though group mean decrements are biologically small and generally do not 

### 30
attain statistical significa nce, a considerable fraction of exposed individuals experienc e 

### 31 clinically meaningful decrements in lung function. 

### 32

1 Not assessed by Adams (2006a ) , uncorrected and O 3 - induced proportions are from Figures 8

- 1B and 8

- 2, respectively, of the 2006 O 3 AQCD ( 2006b )

.

### Draft

– Do Not Cite or Quote 6

- 19 June 2012 Factors Modifying Responsiveness to Ozone

Physical activity increases V ̇ E and therefore the dose of inhaled O 3 . Consequently, the 

### 1 intensity of physiological response during and following an acute O 3 expos ure will be 

### 2 strongly associated with minute ventilation. Apart from inhaled O 3 dose and related 

### 3 environmental factors (e.g., repeated daily exposures), individual

- level factors, such as 

### 4 health status, age, gender, ethnicity, race, smoking habit, diet, and socioeconomic status 

### 5 (SES) have been considered as potential modulators of a physiologic response to such 

### 6

exposures. 

### 7

Responses in Individuals with Pre

- existing Disease
Individuals with respiratory disease are of primary concern in evaluating the health 

### 8
ef fects of O 3 because a given change in function is likely to have more impact on a 

### 9 person with preexisting function impairment and reduced reserve. 

### 10

Possibly due to the age of subjects studied, patients with COPD performing light to 

### 11
moderate exercise do not generally experience statistically significa nt pulmonary 

### 12 function decrements following 1

- and 2

- hour exposures to ≤ 300 ppb O 3 ( Kehrl et al., 

### 13
1985 ; Linn et al., 1983 ; Linn et al., 1982a ; Solic et al., 1982 ) . Following a 4

- hour 

### 14 exposure to 240 ppb O 3 during exercise, Gong et al. (1997b ) found an O 3 - induced FEV 1 

### 15 decrement of 8% in COPD patients which was not statistically different from the 

### 16 decrement of 3% in healthy subjects. Demonstrating the need for control exposures and 

### 17 presumably due to exercise, four of the patients in the Gong et al. (1997b ) study had 

### 18
FEV 1 decrements of >14% following both the FA and O 3 exposures. Although the 

### 19
clinical significa nce is uncertain, small transient decreases in arterial blood oxygen 

### 20
saturation have also been obs erved in some of these studies. 

### 21

Based on studies reviewed in the 1996 and 2006 O 3 AQCDs, asthmatic subjects appear to 

### 22
be at least as sensitive to acute effects of O 3 as healthy nonasthmatic subjects. Horstman 

### 23 et al. (1995 ) found the O 3 - induced FEV 1 decrement in 17 mild

- to

- moderate asthmatics to 

### 24
be significa ntly larger than that in 13 healthy subjects (19% versus 10%, respectively) 

### 25 exposed to 160 ppb O 3 during light exercise ( V ̇ E of 15 L/min per m 2 BSA) for 7.6

- hour 

### 26 exposure. In asthmatics, a significa nt positive correlation between O 3 - induced 

### 27 spirometric responses and baseline lung function was observed, i.e., responses increased 

### 28 with severity of disease. In the shorter duration study by Kreit et al. (1989 ) , 9 asthmatics 

### 29 also showed a considerable larger average O 3 - induced FEV 1 decrement than 9 healthy 

### 30 controls (25% vs. 16% , respectively) following exposure to 400 ppb O 3 for 2 hours with 

### 31
moderate

- heavy exercise ( V ̇ E = 54 L/min). Alexis et al. (2000 ) [400 ppb; 2 h; exercise, 

### 32
V ̇ E = 30 L/mi n] and Jorres et al. (1996 ) [250 ppb; 3 h; exercise, V ̇ E = 30 L/min] reported a 

### 33 tendency for slightly greater FEV 1 decrements in asthmatics than healthy subjects. 

### 34

### Draft

– Do Not Cite or Quote 6

- 20 June 2012 Several studies reported similar responses between asthmatics and healthy individuals 

### 1 ( Scannell et al., 1996 ; Hiltermann et al., 1995 ; Basha et al., 1994 ) . The lack of differences 

### 2
in the Hilter mann et al. (1995 ) [400 ppb; 2 h; exercise, V ̇ E = 20 L/min] and Basha et al. 

### 3 (1994 ) [200 ppb; 6 h; exercise, V ̇ E = 25 L/min] studies was not surprising, however, given 

### 4 extremely small sample sizes (5

- 6 subjects per group) and corresponding lack of 

### 5 statistical power. Power was not likely pr oblematic for Scannell et al. (1996 ) [200 ppb; 

### 6
4 h; exercise, V ̇ E ≈ 44 L/min] with 18 mild asthmatics and 81 age

- matched healthy 

### 7 controls from companion studies ( Balmes et al., 1996 ; Aris et al., 1995 ) . Of note, 

### 8 Mudway et al. (2001 ) reported a tendency for asthmatics to have smaller O 3 - induced 

### 9
FEV 1 decrements than healthy subjects (3% versus 8%, respectively) when exposed to 

### 10
200 ppb O 3 for 2 hours during exercise. However, the asthmatics in ( Mudway et al., 

### 11
2001 ) also tended to be older than the healthy subjects, which could partially explain 

### 12
their smaller re sponse since FEV 1 responses to O 3 diminish with age. 

### 13

In a study published since the 2006 O 3 AQCD, Stenfors et al. (2010 ) exposed pe rsistent 

### 14 asthmatics (n = 13; aged 33 years) receiving chronic inhaled corticosteroid therapy to 

### 15
200 ppb O 3 for 2 hours with moderate exercise. An average O 3 - induced FEV 1 decrement 

### 16 of 8.4% was observed, whereas, only a 3.0% FEV 1 decrement is predicted for s imilarly 

### 17 exposed age

- matched healthy controls ( McDonnell et al., 2007 )

. Vagaggini et al. (2010 ) 

### 18 exposed mild

- to

- moderate asthmatics (n = 23; 33 ± 11 years) to 300 ppb O 3 for 2 hours 

### 19 with moderate exercise. Although the group mean O 3 - in duced FEV 1 decrement was only 

### 20 4%, eight subjects were categorized as “responders” with >10% FEV 1 decrements. 

### 21 Baseline lung function did not differ between the responders and nonresponders 

### 22 suggesting that, in contrast to Horstman et al. (1995 ) , O 3 - induced FEV 1 responses were 

### 23 not associated with disease severity. 

### 24

Lifestage
Children, adolescents, and young adults (<18 years of age) appear, on average, to have 

### 25 nearly equivalent spirometric responses to O 3 , but have greater responses than middle



### 26 aged and older adults when similarly exposed to O 3 ( U.S. EPA, 1996 a ) . Symptomatic 

### 27 responses to O 3 exposure, however, appear to increase with age until early adulthood and 

### 28 then gradually decrease with increasing age ( U.S. EPA, 1996a ) . For example, healthy 

### 29 children (aged 8

- 11 y) exposed to 120 ppb O 3 (2.5 h; heavy intermittent exercise) 

### 30 experienced similar spirometric responses, but lesser symptoms than similarly exposed 

### 31 young healthy adults ( McDonnell et al., 1985a ) . For subjects aged 18

- 36 years, 

### 32 McDonnell et al. (1999b ) reported that symptom responses from O 3 exposure also 

### 33 decrease with increasing age. Diminished symptomatic responses in children and the 

### 34 elderly might put these groups at increased risk for continued O 3 exposure, i.e., a lack of 

### 35 symptoms may result in their not avoiding or ceasing exposure. Once lung growth and 

### 36

### Draft

– Do Not Cite or Quote 6

- 21 June 2012 development reaches the peak (18

- 20 years of age in females and early twenties in 

### 1 males), pulmonary function, which is at its maximum as well, begins to decline 

### 2 progressively with age as does O 3 sensitivity. 

### 3

In healthy individuals, the fastest rate of decline in O 3 responsiveness appears between 

### 4 the ages of 18 and 35 years ( Passannante et al., 1998 ; Seal et al., 1996 ) , more so for 

### 5
females then males ( Hazucha et al., 2003 ) . Durin g the middle age period (35

- 55 years), 

### 6
O 3 sensitivity continues to decline, but at a much lower rate. Beyond this age (>55 years), 

### 7
acute O 3 exposure elicits minimal spirometric changes. Whether the same age

- dependent 

### 8 pattern of O 3 sensitivity decline also holds for nonspirometric pulmonary function, 

### 9 airway reactivity or inflammatory endpoints has not been determined. Although there is 

### 10 considerable evidence that spirometric and symptomatic responses to O 3 exposure 

### 11 decrease with age beyond young adulthood, th is evidence comes from cross

- sectional 

### 12 analyses and has not been confirmed by longitudinal studies of the same individuals. 

### 13

Sex
Several studies have suggested that physiological differences between sexes may 

### 14 predispose females to greater O 3 - induced health effects. In females, lower plasma and 

### 15 nasal lavage fluid (NLF) levels of uric acid (the most prevalent antioxidant), the initial 

### 16
defense mechanism of O 3 neutralization in airway surface liquid, may be a contributing 

### 17
factor ( Housley et al., 1996 ) . Consequently, reduced absorption of O 3 in the upper 

### 18 airways may promote its deeper penetration. Dosimetric measurements have shown that 

### 19 the absorption distribution of O 3 is independent of sex when absorption is normalized to 

### 20 anatomical dead space ( Bush et al., 1996 ) . Thus, a se x

- related differential removal of O 3 

### 21 by uric acid seems to be minimal. In general, the physiologic response of young healthy 

### 22
females to O 3 exposure appears comparable to the response of young males ( Hazucha et 

### 23 al., 2003 ) . Several studies have investigated the effects of the menstrual cycle on 

### 24 responses to O 3 in healthy young women. In a study of 9 women exposed during exercise 

### 25
to 300 ppb O 3 for an hour, Fox et al. (1993 ) found lung function responses to O 3 

### 26 significa ntly enhanced durin g the follicular phase relative to the luteal phase. However, 

### 27 Weinmann et al. (1995c ) found no difference in responses between the follicular and 

### 28 luteal phases as well as no significa nt differences between 12 males and 12 females 

### 29 exposed during exercise to 350 ppb O 3 for 2.15 hours. Seal et al. (1996 ) also reported no 

### 30 effect of menstrual cycle phase in their analysis of responses of 150 women (n = 25 per 

### 31 exposure group; 0, 120, 240, 300, and 400 ppb O 3 ). Seal et al. (1996 ) conceded that the 

### 32 methods used by Fox et al. (1993 ) more precisely defined menstrual cycle phase. 

### 33

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- 22 June 2012 Ethnicity
Only two controlled human exposure studies have assessed differences in lung function 

### 1 responses between races. Seal et al. (1993 ) compared lung function responses of whites 

### 2 (93 M, 94 F) and blacks (undefined ancestry; 92 M, 93 F) exposed to a range of O 3 

### 3 concentrations (0

- 400 ppb). The main effects of the sex

- race group and O 3 concentration 

### 4 were statistically significa nt (both at p <0.001), although the interaction between sex

- race 

### 5 group and O 3 concentration was not significa nt (p = 0.13). These findings indicate some 

### 6
overall difference between the sex

- race groups that is independent of O 3 concentration, 

### 7 i.e., the concentration

- response (C

- R) curves for the four sex

- race groups are parallel. In 

### 8 a multiple comparison procedure on data collapsed acr oss all O 3 concentrations for each 

### 9

sex

- race group, both black men and black women had significa ntly larger decrements in 

### 10
FEV 1 than did white men. The authors noted that the O 3 dose per unit of lung tissue 

### 11 would be greater in blacks and females than whites and males, respectively. It cannot be 

### 12 ruled out that this difference in tissue dose might have affected responses to O 3 . The 

### 13 college students recruited for the Seal et al. (1993 ) study were noted by the authors as 

### 14 probably being from better educated a nd SES advantaged families, thus reducing the 

### 15 potential influence of these variables on results. In a follow

- up analysis, Seal et al. (1996 ) 

### 16 reported that, of three SES categories, indiv iduals in the middle SES category showed 

### 17 greater concentration

- dependent decline in percent

- predicted FEV 1 (4

- 5% at 400 ppb O 3 ) 

### 18 than low and high SES groups. The authors did not have an “immediately clear” 

### 19 explanation for this finding. 

### 20

More recently, Que et a l. (2011 ) assessed pulmonary responses in blacks of African 

### 21 American ancestry (22 M, 24 F) and Caucasians (55 M, 28 F) exposed to 220 ppb O 3 for 

### 22 2.25 hours (alternating 15 min periods of rest and brisk treadmill walking). On average, 

### 23 the black males exp erienced a 16.8% decrement in FEV 1 following O 3 exposure which 

### 24

was significa ntly larger than mean FEV 1 decrements of 6.2, 7.9, and 8.3% in black 

### 25 females and Caucasian males and Caucasian females, respectively. In the study by Seal et 

### 26 al. (1993 ) , there was potential that the increased FEV 1 decrements in blacks relative to 

### 27
whites were due to increased O 3 tissue doses since exercise rates were normalized to 

### 28
BSA. Differences in O 3 tissue doses between the races should not have occurred in the 

### 29 Que et al. (2011 ) study because exercise rates were normalized to lung volume (viz., 

### 30
6

- 8 times FVC). Thus, the increased mean FEV 1 decrement in black males is not likely 

### 31 attributable to systematically larger O 3 tissue doses in blacks relative to whites. 

### 32

Smoking

Smokers are less responsive to O 3 for some (but not all) health endpoints than 

### 33 nonsmokers. Spirometric and plethysmographic pulmonary function decline, respiratory 

### 34 symptoms, and nonspecific airway hyperreactivity of smokers to O 3 were all weaker than 

### 35

### Draft

– Do Not Cite or Quote 6

- 23 June 2012 data reported for nonsmokers. However, the time course of development and recovery of 

### 1 these effects as well their reproducibility in smokers was not different from nonsmokers 

### 2 ( Frampton et al., 1997a ) . Another similarity between smokers and nonsmokers is that, the 

### 3 inflammatory response to O 3 does not appear to depend on smoking status nor the 

### 4 responsiveness of individuals to changes in lung function ( Torres et al., 1997 ) . Chronic 

### 5 airway inflammation with desensitization of bronchial nerve endings and an increa sed 

### 6 production of mucus may plausibly explain the reduced responses to O 3 in smokers 

### 7
relative to nonsmokers ( Frampton et al., 1997a ; Tor res et al., 1997 )

. 

### 8

Antioxidant supplementation
The first line of defense again st oxidative stress is antioxidants

- rich ELF which 

### 9 scavenges free radicals and limits lipid peroxidation. Exposure to O 3 depletes the 

### 10 antioxidant level in nasal ELF probably due to scrubbing of O 3 ( Mudway et al., 1999a )
, 

### 11 however, the concentration and the activity of antioxidant enzymes either in ELF or 

### 12 plasma do not appear to be related to O 3 responsiveness ( Samet et al., 2001 ; Avissar et 

### 13 al., 2000 ; Blomberg et al., 1999 ) . Carefully controlled studies of dietary antioxidant 

### 14 supplementation have demonstrated some protective effects of α

- tocopherol and 

### 15

as corbate on spirometric lung function from O 3 but not on the intensity of subjective 

### 16 symptoms and inflammatory response including cell recruitment, activation and a release 

### 17
of mediators ( Samet et al., 2001 ; Trenga et al., 200 1 ) . Dietary antioxidants have also been 

### 18 reported to attenuate O 3 - induced bronchial hyperresponsiveness in asthmatics ( Trenga et 

### 19 al., 2001 )

. 

### 20

Genetic polymorphisms

Some studies (e.g., Corradi et al., 2002 ; Bergamaschi et al., 2001 ) reviewed in the 2006 

### 21
O 3 AQCD reported that genetic polymorphisms of antioxidant enzymes may modulate 

### 22 pulmonary function and inflammatory response to O 3 challenge. It was suggested that 

### 23 healthy carriers of NAD(P)H:quinone oxidoreductase wild type (NQO1wt) in 

### 24 combination with glutathione S

- transferase μ

- 1 genetic deficien cy (GSTM1null) were 

### 25 more responsive to O 3 . Bergamaschi et al. (2001 ) reported that subjects having NQO1wt 

### 26 and GSTM1null genotypes had increased O 3 responsiveness (FEV 1 decrements and 

### 27 epithelial permeasbility), whereas subje cts with other combinations of these genotypes 

### 28 were less affected. A subsequent study from the same laboratory reported a positive 

### 29
association between O 3 responsiveness, as characterized by the level of oxidative stress 

### 30 and inflammatory mediators (8

- isopro stane, LTB 4 and TBARS) in exhaled breath 

### 31 condensate and the NQO1wt and GSTM1null genotypes ( Corradi et al., 2002 ) . However, 

### 32 none of the spirometric endpoints (e. g., FEV 1 ) were affected by O 3 exposure. 

### 33

### Draft

– Do Not Cite or Quote 6

- 24 June 2012 In a controlled exposure of mild

- to

- moderate asthmatics (n = 23; 33 ± 11 years) to 

### 1
300 ppb O 3 for 2 hours with moderate exercise, Vagaggini et al. (2010 ) found that six of 

### 2 the subjects had a NQO1 wt and GSTM1 null, but this genotype was not associated with 

### 3 the changes in lung function or inflammatory responses to O 3 . Kim et al. (2011 ) also 

### 4
recentl y reported that GSTM1 genotype was not predictive of FEV 1 responses in young 

### 5 healthy adults (32 F, 27 M; 25.0 ± 0.5 year) who were roughly half GSTM1

- null and half 

### 6
GSTM1

- sufficient. Sputum neutrophil levels, measured in a subset of the subjects (13 F, 

### 7
11 M ), were also not significa ntly associated with GSTM1 genotype. 

### 8

In a study of healthy volunteers with GSTM1 sufficient (n = 19; 24 ± 3) and GSTM1 null 

### 9 (n = 16; 25 ± 5) genotypes exposed to 400 ppb O 3 for 2 hours with exercise, Alexis et al. 

### 10 (2009 ) found that inflamma tory responses but not lung function responses to O 3 were 

### 11 dependent on genotype. At 4 hours post

- O 3 exposure, both GSTM1 genotype groups had 

### 12 significa nt increases in sputum neutrophils with a tendency for a greater increase in 

### 13
GSTM1 sufficient than nulls. At 24 hours postexposure, sputum neutrophils had returned 

### 14 to baseline levels in the GSTM1 sufficient individuals. In the GSTM1 null subjects, 

### 15 however, sputum neutrophil levels increased from 4 hours to 24 hours and were 

### 16 significa ntly greater than both base line levels and levels at 24 hours in the GSTM1 

### 17
sufficient individuals. Since there was no FA control in the Alexis et al. (2009 ) study, 

### 18 effects of the exposure other than O 3 itself cannot be ruled out. In general, the findings 

### 19
between studies are inconsistent. 

### 20

Bod y Mass Index
In a retrospective analysis of data from 541 healthy, nonsmoking, white males between 

### 21 the ages of 18

- 35 years from 15 studies conducted at the U.S. EPA Human Studies 

### 22 Facility in Chapel Hill, NC, McDonnell et al. (2010 ) found that increased BMI was 

### 23
associated with enhanced FEV 1 responses to O 3 . The BMI effect was of the same order of 

### 24 magnitude but in the opposite direction of the age eff ect where by FEV 1 responses 

### 25 diminish with increasing age. In a similar retrospective analysis, Bennett et al. (2007 ) 

### 26
found enhanced FEV 1 decrements following O 3 exposure with increasing BMI in a group 

### 27 of 75 healthy, nonsmoking, women (age 24 ± 4 years; BMI ra nge 15.7 to 33.4), but not 

### 28 122 healthy, nonsmoking, men (age 25 ± 4 years; BMI range 19.1 to 32.9). In the women, 

### 29 greater O 3 - induced FEV 1 decrements were seen in overweight (BMI >25) than in normal 

### 30 weight (BMI from 18.5 to 25), and in normal weight than in underweight (BMI <18.5) 

### 31 (P trend ≤ 0.022). Together, these results indicate that higher BMI may be a risk factor 

### 32 for pulmonary effects associated with O 3 exposure. 

### 33

### Draft

– Do Not Cite or Quote 6

- 25 June 2012 Repeated Ozone Exposure Effects

The attenuation of responses observed after repeated consec utive O 3 exposures in 

### 1 controlled human exposure studies has also been referred to in the literature as 

### 2 “adaptation” or “tolerance” ( e.g., Linn et al., 1988 ) . In animal toxicology studies, 

### 3 however, the term tolerance has more classically been used to describe the phenomenon 

### 4 wherein a prior exposure to a low, nonlethal concentration of O 3 provides some 

### 5

p rotection against death and lung edema at a higher, normally lethal exposure 

### 6
concentration ( see Section 9.3.5 of U.S. EPA, 1986 ) . The term “attenuation” will be used 

### 7 herein to refer to the reduction in responses to O 3 observed with repeated O 3 exposu res in 

### 8 controlled human exposure studies. Neither tolerance nor attenuation should be presumed 

### 9 to imply complete protection from the biological effects of inhaled O 3 , because 

### 10 continuing injury still occurs despite the desensitization to some responses. 

### 11

Th e attenuation of responses due to ambient O 3 exposure was first investigated by 

### 12 Hackney et al. (1976 ) ; ( 1977a ) . Experiencing frequent ambient O 3 exposures, Los 

### 13 Angeles residents were compared to groups having less ambient O 3 exposure. Following 

### 14 a controlled laboratory exposure to 370

- 400 ppb O 3 for 2 hours with light intermittent 

### 15 exercise (2

- 2.5 times resting V ̇ E ), the Los Angeles residents exhibited minimal FEV 1 

### 16 responses relative to groups having less ambient O 3 exposure. Subsequently, Linn et al. 

### 17 (1988 ) examined the seaso nal variation in Los Angeles residents’ responses to O 3 

### 18 exposure. A group of 8 responders (3M, 5F) and 9 nonresponders (4M, 5F) were exposed 

### 19
to 180 ppb O 3 for 2 hours with heavy intermittent exercise ( V ̇ E = 35 L/min per m 2 BSA) 

### 20 on four occasions (spring, fa ll, winter, and the following spring). In responders, relative 

### 21 to the first spring exposures, FEV 1 responses were attenuated in the fall and winter, but 

### 22 returned to similar decrements the following spring. By comparison, the nonresponders, 

### 23 on average, show ed no FEV 1 decrements on any of the four occasions. In subjects 

### 24 recruited regardless of FEV 1 responsiveness to O 3 from the area around Chapel Hill, NC, 

### 25
no seasonal effect of ambient O 3 exposure on FEV 1 responses following chamber 

### 26 exposures to O 3 has been o bserved ( Hazucha et al., 2003 ; McDonnell et al., 1985b )

. 

### 27

Based on studies reviewed in previous O 3 AQCDs, several conclusions can be drawn 

### 28 about repeated 1

- to 2

- h O 3 exposures. Repeated exposures to O 3 causes enhanced 

### 29 (i.e., greater decrements) FVC and FEV 1 responses on the second day of exposure. The 

### 30 enhanced response appears to depend to some extent on the magnitude of the initial 

### 31

response ( Horvath et al., 1981 ) . Small responses to the first O 3 exposure are less likely to 

### 32 result in an enhanced respons e on the second day of O 3 exposure ( Folinsbee et al., 1994 )

. 

### 33 With continued daily exposures (i.e., beyond the second day) there is a substantial (or 

### 34 even total) attenuation of pulmonary function responses, typically on the third to 

### 35
fifth days of repeated O 3 exposure. This attenuation of responses i s lost in 1 week ( Kulle 

### 36

### Draft

– Do Not Cite or Quote 6

- 26 June 2012 et al., 1982 ; Linn et al., 1982b ) or perhaps 2 weeks ( Horvath et al., 1981 ) without O 3 

### 1 exposure. In temporal conjunction with pulmonary function changes, symptoms induced 

### 2 by O 3 (e.g., cough, pain on deep inspiration, and chest discomfort), are also increased on 

### 3 the second exposure day but are attenuated with repeated O 3 exposure thereafter ( U.S. 

### 4 EPA, 1998b ; Foxcroft and Adams, 1986 ; Linn et al., 1982b ; Folinsbee et al., 1980 ) . In 

### 5 longer

- duration (4

- 6.6 hours), lower

- concentration studies that do not cause an enhanced 

### 6
second

- day respons e, the attenuation of response to O 3 appears to proceed more rapidly 

### 7 ( Folinsbee et al., 1994 )

. 

### 8

Consistent with other investigators, Frank et al. (2001 ) found FVC and FEV 1 decrements 

### 9
to be significa ntly attenuated following four consecutive days of exposure to O 3 

### 10 (250 ppb, 2 h). However, the effects of O 3 on the small airways (assessed by a combined 

### 11 index of isovolumetric forced expiratory flow between 25 and 75% of vital capacity 

### 12 [FEF 25

- 75 ] and flows at 50% and 75% of FVC) showed a persistent functional reduction 

### 13 from Day 2 through Day 4. Notably, in contrast to FVC and FEV 1 which exhi bited a 

### 14 recovery of function between days, there was a persistent effect of O 3 on small airways 

### 15 function such that the baseline function on Day 2 through Day 4 was depressed relative to 

### 16 Day 1. Frank et al. (2001 ) also found neutrophil (PMN) numbers in BAL remained 

### 17 significa ntly higher following O 3 (24 hours after last O 3 exposure) compared to FA. 

### 18 Markers from bronchioalveolar lavage fluid (BALF) following 4 consecutive days of 

### 19
both 2

- hour ( Devlin et al., 1997 ) and 4

- hour ( Jorres et al., 2000 ; Christian et al., 1998 ) 

### 20 exposures have indicated ongoing cellular damage irrespective of the attenuation of some 

### 21 cellular inflammatory responses of the airways, lung function and symptoms response. 

### 22 These data suggest that the persistent small airways dysfunction assessed by Frank et al. 

### 23 (2001 ) is likely induced by both neurogenic and inflammatory me diators, since the 

### 24 density of bronchial C

- fibers is much lower in the small than large airways. 

### 25

Summary of Controlled Human Exposure Studies on Lung Function

Responses in humans exposed to ambient O 3 concentrations include: decreased 

### 26 inspiratory capacity ; mild bronchoconstriction; rapid, shallow breathing pattern during 

### 27 exercise; and symptoms of cough and pain on deep inspiration ( U .S. EPA, 2006b
, 1996a )

. 

### 28 Discussed in subsequent Section 6.2.2.1 and Section 6.2.3.1 , exposure to O 3 also results 

### 29 in airway hyperresponsiveness, pul monary inflammation, immune system activation, and 

### 30 epithelial injury ( Que et al., 2011 ; Mudway and Kelly, 2004a ) . Reflex inhibition of 

### 31 inspiration results in a decrease in forced vital capacity and, in combination with mild 

### 32 bronchoconstriction, contributes to a decrease in the FEV 1 . Health y young adults exposed 

### 33
to O 3 concentrations ≥ 60 ppb develop statistically significa nt reversible, transient 

### 34 decrements in lung function and symptoms of breathing discomfort if minute ventilation 

### 35 or duration of exposure is increased sufficiently ( Kim et al., 2011 ; McDonnell et al., 

### 36

### Draft

– Do Not Cite or Quote 6

- 27 June 2012 2010 ; Schelegle et al., 2009 ; Brown et al., 2008 ; Adams, 2006a ) . With repeated O 3 

### 1 exposures over several days, FEV 1 and symptom responses become attenuated in both 

### 2 healthy individua ls and asthmatics, but this attenuation of responses is lost after about 

### 3

a week without exposure ( Gong et al., 1997a ; Folinsbee et al., 1994 ; Kulle et al., 1982 )

. 

### 4
In contrast to the attenuation of FEV 1 respon ses, there appear to be persistent O 3 effects 

### 5 on small airways function as well as ongoing cellular damage during repeated exposures. 

### 6

There is a large degree of intersubject variability in lung function decrements 

### 7 ( McDonnell, 1996 ) . However, these lung function responses tend to be reproducible 

### 8 within a given individual over a period of several months indicating differences in the 

### 9 intrinsic responsiveness of individuals ( Hazucha et al., 2003 ; McDonnell et al., 1985b )

. 

### 10
In hea lthy young adults, O 3 - induced decrements in FEV 1 do not appear to depend on 

### 11 gender ( Hazucha et al., 2003 ) , body surface area or height ( McDonnell et al., 1997 ) , lung 

### 12
size or baseline FVC ( Messineo and Adams, 1990 ) . There is limited evidence that blacks 

### 13 may experience greater O 3 - induced decrements in FEV 1 than age

- mat ched whites ( Que et 

### 14 al., 2011 ; Seal et al., 1993 ) . Healthy children experience similar spirometric responses 

### 15
but lesser s ymptoms from O 3 exposure relative to young adults ( McDonnell et al., 

### 16
1985a ) . On average, spirometric and symptom responses to O 3 exposure appear to decline 

### 17 with increasing age beyond about 18 ye ars of age ( McDonnell et al., 1999b ; Seal et al., 

### 18
1996 ) . There is a tendency for slightly increased spirometric responses in individuals 

### 19
with mild ast hma and allergic rhinitis relative to healthy young adults ( Jorres et al., 

### 20
1996 ) . Spirometric responses in asthmatics appear to be affected by baseline lung 

### 21 function, i.e., responses increase with disease severity ( Horstman et al., 1995 )

. 

### 22

Available information on recovery of lung function following O 3 exposure indicates that 

### 23 an initial phase of recovery in healthy individuals proceeds relatively rapidly, with acute 

### 24 spirometric and symptom responses resolving within about 2 to 4 h ours ( Folinsbee and 

### 25 Hazucha, 1989 ) . Small residual lung function effects are almost completely resolved 

### 26 within 24 h. One day following O 3 exposure, persistent effects on the small airways 

### 27 assessed by decrements in FEF 25

- 75 and altered ventilation distribution have been reported 

### 28 ( Frank et al., 2001 ; Foster et al., 1997 )

. 

### 29

6.2.1.2 Epidemiology

The O 3 - induced lung function decrements consistently demonstr ated in controlled human 

### 30 exposure studies (Section 6.2.1.1 ) provide biological plausibility for the epidemiologic 

### 31 evidence consistently linking shor t

- term increases in ambient O 3 concentration with lung 

### 32 function decrements in diverse populations. In the 1996 and 2006 O 3 AQCDs, coherence 

### 33 with controlled human exposure study results was found not only for epidemiologic 

### 34

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– Do Not Cite or Quote 6

- 28 June 2012 associations observed in groups wi th expected higher ambient O 3 exposures and higher 

### 1 exertion levels, including children attending summer camps and adults exercising or 

### 2 working outdoors, but also for associations observed in children and individuals with 

### 3
asthma ( U.S. EPA, 2006b
, 1996a ) . Recent epidemiologic studies focused more on 

### 4
chi ldren with asthma rather than groups with increased outdoor exposures or other 

### 5 healthy populations. Whereas recent studies contributed less consistent evidence, the 

### 6 cumulative body of evidence indicates decreases in lung function in association with 

### 7
increa ses in ambient O 3 concentration in children with asthma. Collectively, studies in 

### 8
adults with asthma and individuals without asthma found both O 3 - associated decreases 

### 9 and increases in lung function. Recent studies did provide additional data to assess 

### 10
whet her particular lags of O 3 exposure were more strongly associated with decrements in 

### 11 lung function; whether O 3 associations were confounded by copollutant exposures; and 

### 12 whether associations were modified by factors such as corticosteroid (CS) use, genetic 

### 13 polymorphisms, and elevated BMI. 

### 14

Populations with Increased Outdoor Exposures

Epidemiologic studies primaril y use ambient O 3 concentrations to represent exposure; 

### 15 however, few studies have accounted for time spent outdoors, which has been shown to 

### 16 influence the relationship between ambient concentrations and individual exposures to O 3 

### 17 (Section 4.3.3 ). Epidemiologic studies of individuals engaged in outdoor recreation, 

### 18 exercise, or work are noteworthy for the likely greater extent to which ambient O 3 

### 19

concen trations represent ambient O 3 exposures. Ambient O 3 concentrations, locations, 

### 20 and time periods for epidemiologic studies of populations with increased outdoor 

### 21 exposures are presented in Table 6

- 2 . Most of these studies measured ambient O 3 at the 

### 22 site of subjects’ outdoor activity and related lung function changes to the O 3 

### 23 concentrations measured during outdoor activity, which have contributed to highe r O 3 

### 24 personal exposure

- ambient concentration correlations and ratios (Section 4.3.3 ). Because 

### 25 of improved O 3 exposure estimates, measurement of lun g function before and after 

### 26 discrete periods of outdoor activity, and examination of O 3 effects during exertion when 

### 27
the dose of O 3 reaching the lungs may be higher due to higher ventilation and inhalation 

### 28 of larger volumes of air, epidemiologic studies of populations with increased outdoor 

### 29 exposures are more comparable to controlled human exposure studies. Further, these 

### 30 epidemiologic studies provide strong evidence for respiratory effects in children and 

### 31
adults related to ambient O 3 exposure. Similar to f indings from controlled human 

### 32 exposure studies, the collective body of epidemiologic evidence clearly demonstrates 

### 33 decrements in lung function in association with increases in ambient O 3 exposure during 

### 34 periods of outdoor activity ( Figure 6

- 3 to Figure 6

- 5 and Table 6

- 3 to Table 6

- 5 ). 

### 35

### Draft

– Do Not Cite or Quote 6

- 29 June 2012 Table 6

- 2 Mean and upper percentile ozone concentrations in epidemiologic studies of lung function in populations with increased outdoor exposure s

. Study * Location Study Period O 3 Averaging Time Mean/Median Concentration (ppb) Upper Percentile Concentrations (ppb)

Thurston et al. ( 1997 ) Connecticut River Valley, CT June 1991

- 1993 1

- h max 83.6 Max: 160

Berry et al. (1991 ) Mercer County, NJ July 1988 1

- h max a NR Max: 204

Spektor and Lippmann (1991 ) Fairview Lake, NJ July

- August 1988 1

- h avg b 69 Max: 137

Avol et al. (1990 ) Idyllwild, CA June

- August 1988 1

- h avg b 94 Max: 161

Burnett et al. (1990 ) Lake Couchiching, Ontario, Canada June

- July 1983 1

- h avg b 59 Max: 95

Higgins et al. (1990 ) San Bernardino, CA June

- July 1987 1

- h avg b 123 Max: 245

Raizenne et al. (1989 ) Lake Erie, Ontario, Canada July

- August 1986 1

- h avg b 71 Max: 143

Spektor et al. (1988a ) Fairview Lake, NJ July

- August 1984 1

- h avg b 53 Max: 113

Neas et al. (1999 ) Philadelphia, PA July

- September 1993 12

- h avg a (9 a.m.
- 9 p.m.) 57.5 (near Camp 1) 55.9 (near Camp 2) Max (near Camp 1): 106

Nickmilder et al. (2007 ) Southern Belgium July

- August 2002 1

- h max 8

- h max NR Max (across 6 camps): 24.5

- 112.7 c Max (across 6 camps): 18.9

- 81.1 c

Girardot et al. (2006 ) Great Smoky Mountain NP, TN August

- October 2002 June

August 2003 Hike

- time avg (2

- 9 h) d 48.1 Max: 74.2

Korrick et al. (1998 ) Mt. Washington, NH Summers 1991, 19 92 Hike

- time avg (2

- 12 h) d 40 Max: 74

Hoppe et al. (2003 ) Munich, Germany Summers 1992

- 1995 30

- min max (1

- 4 p.m.) High O 3 days: 65 .9 Control O 3 days: 27.2 Max (high O 3 days): 86

Spektor et al. (1988b ) Tuxedo, NY June

- August 1985 Exercise

- time avg (15

- 55 min) NR Max: 124

Selwyn et al. (1985 ) Houston, TX May

- October 1981 Exercise

- time 15

- min max (4

- 7 p.m.) 47 Max: 135

Brunekreef et al. (1994 ) Eastern Netherlands June

- August 1981 Exercise

- time avg a (10

- 145 min) 42.8 c Max: 99.5 c

Braun

Fahrlander et al. (1994 ) Southern Switzerland May

- October 1989 Exercise

- time 30

- min avg NR Max: 80 c

Castillejos et al. (1995 ) Mexico City, Mexico June 1990

- October 1991 1

- h max a 179 Max: 365

Hoek et al. (199 3 ) Wageningen, Netherlands May

- July 1989 1

- h max a NR Max: 122 c

### Draft

– Do Not Cite or Quote 6

- 30 June 2012 Study * Location Study Period O 3 Averaging Time Mean/Median Concentration (ppb) Upper Percentile Concentrations (ppb)

Hoppe et al. (1995 ) Munich, Germany Summers 1992

- 1995 30

- min max (1

- 4 p.m.) High O 3 days: 64 Control O 3 days: 32 Max (high O 3 days): 77

Chan and Wu (2005 ) Taichung City, Taiwan November

December 2001 8

- h avg (9 a.m.

- 5 p.m.)
1

- h max 35.6 52.6 Max: 65.1 95.5

Brauer et al. (1996 ) British Columbia, Canada June

- August 1993 1

- h max a 40 Max: 84

Romieu et al. (1998b ) Mexico City, Mexico March

- August 1996 Work

- shift avg (6

- 12 h) a 67.3 95th: 105.8

Thaller et al. (2008 ) Galveston, TX Summer 2002

- 2004 1

- h max 35 (median) Max: 118

* Note: Studies presented in order of first appearance in the text of this section. NR = not reported.

a Some or all measurements obtained from monitors located off site of outdoor activity.

b 1

- h avg, preceding lung function measurement, as reported in the pooled analysis by Kinney et al. (1996 )

.
c Concentrations converted from μg/m 3 to ppb using the conversion factor of 0.51 assuming standard temperature (25°C) and pressure (1 atm).

d Individual

- level estimates calculated from concentrations measured in different segments of hiking trail.

Children Attending Summer Camps

Studies of children attending summer camps, most of which were discussed in the 1996 

### 1
O 3 AQCD, have provided important evidence of the impact of ambient O 3 exposure on 

### 2 respiratory effects in young, healthy children. In addition to the improved exposure 

### 3
assessment as d escribed above, these studies were noted for their daily assessment of 

### 4 lung function by trained staff over 1

- to 2

- week periods in the mornings and late 

### 5 afternoons before and after hours of outdoor activity ( Thurston et al., 1997 ; Berry et al., 

### 6
1991 ; Spektor and Lippmann, 1991 ; Avol et al., 1990 ; Burnett et al., 1990 ; Higgins et al., 

### 7
1990 ; Raizenne et al., 1989 ; Spektor et al., 1988a )

. 

### 8

In groups mostly comprising healthy children (ages 7

- 17 years), decrements in FEV 1 

### 9 were associated consistently with increases in ambient O 3 concentration averaged over 

### 10
the 1

- 12 hours preceding lung function measurement ( Figure 6

- 3 and Table 6

- 3 ). Kinney 

### 11 et al. (1996 ) corroborated this association in a re

- analysis combining 5,367 lung function 

### 12 measurements collected from 616 healthy children from six studies ( Spektor and 

### 13 Lippmann, 1991 ; Avol et al., 1990 ; Burnett et al., 1990 ; Higgins et al., 1990 ; Raizenne et 

### 14 al., 1989 ; Spektor et al., 1988a ) . Based on uniform statistical m ethods, a

- 20 ml (95% CI: 

### 15

- 25,

- 14) change in afternoon FEV 1 was estimated for a 40

- ppb increase in O 3 

### 16 concentration averaged over the 1 hour before lung function measurement ( Kinney et al., 

### 17
1996 ) (all effect estimates are standardized to increments specific to the O 3 averaging 

### 18
time as detailed in Section 2.1 ). All of the studies in the pooled analysis were conducted 

### 19

### Draft

– Do Not Cite or Quote 6

- 31 June 2012 during summer months but were diverse in locations examined (i.e., Northeast U.S., 

### 1 Canada, California), range in ambient concentrations of O 3 (presented within Table 6

- 2 ) 

### 2 and other pollutants measured, and magnitudes of association observed. Study

- specific 

### 3 effect estimates ranged between a 0.76 and 48 mL decrease or a 0.3% to 2.2% decrease in 

### 4 study mean FEV 1 per 40

- ppb increase in 1

- h avg O 3 . 

### 5

Among camp studie s included the pooled analysis plus others, associations for peak 

### 6 expiratory flow (PEF) were more variable than were those for FEV 1 , as indicated by the 

### 7 wider range in effect estimates and wider 95% CIs ( Figure 6

- 3 and Table 6

- 3 ). 

### 8 Nonetheless, in most cases, increases in ambient O 3 concentration wer e associated with 

### 9 decreases in PEF. The largest O 3 - associated decrease in PEF (mean 2.8% decline per 

### 10
40

- ppb increase in 1

- h max O 3 ) was found in a group of campers with asthma, in whom 

### 11
an increase in ambient O 3 concentration also was associated with increa ses in chest 

### 12 symptoms and bronchodilator use ( Thurston et al., 1997 )

. 

### 13

For both FEV 1 and PEF, the magnitude of association was not related to t he study mean 

### 14
ambient 1

- h avg or max O 3 concentration. With exclusion of results from Spektor and 

### 15 Lippmann (1991 ) , larger O 3 - associated FEV 1 decrements were found in populations with 

### 16
lower mean FEV 1 . No trend was found with mean PEF. Sufficient data were not provided 

### 17 to assess whether the temporal variability in O 3 concentrations, activity levels of subjects, 

### 18 or associations with other polluta nts contributed to between

- study heterogeneity in O 3 

### 19
effect estimates. 

### 20

### Draft

– Do Not Cite or Quote 6

- 32 June 2012 Note: Results generally are presented in order of increasing mean ambient O 3 concentration. Effect estimates are from single

pollutant models and are standardized to a 40

- ppb increase for 1

- h avg or 1

- h max O 3 concentration and a 30

- ppb increase for 12

- h avg O 3 concentration.


### Figure 6

- 3 Changes in FEV 1 

### (mL) or PEF (mL/sec) in association with ambient ozone concentrations among children at tending summer camp. Study FEV 1 (ml) Spektor et al. (1988a) Spektor and Lippmann (1991)

Raizenne et al. (1989) Burnett et al. (1990)

Higgins et al. (1990) Avol et al. (1990)

Kinney et al. (1996) Berry et al. (1991) Population

Campers without asthma Campers without asthma

Campers without asthma Campers without asthma

Campers without asthma Campers without asthma

Pooled estimate Campers without asthma

- 160

- 120

- 80

- 40 0 40 80
Change in FEV 1 (ml) per unit increase in ambient O 3 (95% CI)

PEF (ml/sec) Spektor et al. (1988a)

Raizenne et al. (1989) Burnett et al. (1990)

Higgins et al. (1990) Avol et al. (1990)

Kinney et al. (1996)

Berry et al. (1991) Neas et al. (1999) Thurston et al. (1997) Campers without asthma

Campers without asthma Campers without asthma

Campers without asthma Campers without asthma

Pooled estimate

Campers without asthma Campers without asthma Campers with asthma ◄

◄ ►

- 160

- 120

- 80

- 40 0 40 80
Change in PEF (ml/sec) per unit increase in ambient O 3 (95% CI)

### Draft

– Do Not Cite or Quote 6

- 33 June 2012 Table 6

- 3 Additional characteristics and quantitative data for studies represented in Figure 6

- 3.

Study Location Population, Mean FEV 1 (mL) or PEF (mL/sec) Standardized Percent Change (95% CI) a Standardized Effect Estimate (95% CI) a

FEV 1 (mL)
Spektor et al. (1988a ) Fairview Lake, NJ 91 campers without asthma ages 8

- 15 yr, 2,140 - 0.93 (

- 1.5,

- 0.35) b

- 20.0 (

- 32.5,

- 7.5) b

Spektor and Lippmann (1991 ) Fairview Lake, NJ 46 campers without asthma ages 8

- 14 yr, 2,390 - 2.2 (

- 3.0,

- 1.3) b

- 51.6 (

- 72.8,

- 30.4) b

Burnett et al. (1990 ) Lake Couchiching, Ontario, Canada 29 campers without asthma ages 7

- 15 yr, 2,410 - 0.32 (

- 1.7, 1.1) b

- 7.6 (

- 42.1, 26.9) b

Raizenne et al. (1989 ) Lake Erie, Ontario, Canada 112 campers without asthma mean age 11.6 yr, 2,340 - 0.50 (

- 0.83,

- 0.16) b

- 11.6 (

- 19.4,

- 3.8) b

Avol et al. (1990 ) Pine Springs, CA 295 campers without asthma ages 8

- 17 yr, 2,190 - 0.58 (

- 1.0,

- 0.12) b

- 12.8 (

- 23.0,

- 2.6) b

Higgins et al. (1990 ) San Bernardino, CA 43 campers without asthma ages 7

- 13 yr, 2,060 - 1.6 (

- 2.4,

- 0.87) b

- 33.6 (

- 49.3,

- 17.9) b

Kinney et al. (1996 ) Pooled analysis of preceding 6 studies 616 campers without asthma ages 7

- 17 yr, 2,300 - 0.87 (

- 1.1,

- 0.63)

- 20.0 (

- 25.5,

- 14.5) b

Berry et al. (1991 ) Hamilton, NJ 14 campers without asthma 58% age <14 yr, NA NA 32.8 (6.9, 58.7)

PEF (mL/sec)
Spektor et al. (1988a ) Fairview Lake, NJ 91 campers without asthma ages 8

- 15 yr, 4,360 - 1.8 (

- 3.3,

- 0.40)

- 80.0 (

- 142.7,

- 17.3) b

Burnett et al. (1990 ) Lake Couchiching, Ontario, Canada 29 campers without asthma ages 7

- 15 yr, 5,480 - 1.9 (

- 3.8,

- 0.05)

- 106.4 (

- 209.9,

- 2.9) b

Raizenne et al. (1989 ) Lake Erie, Ontario, Canada 112 campers without asthma mean age 11.6 yr, 5,510 - 0.07 (

- 0.56, 0.41)

- 4.0 (

- 30.7, 22.7) b

Avol et al. (1990 ) Pine Springs, CA 295 campers without asthma ages 8

- 17 yr, 4,520 1.9 (0.71, 3.1) 86.8 (31.9, 142) b

Higgins et al. (1990 ) San Bernardino, CA 43 campers without asthma ages 7

- 13 yr, 5,070 - 0.87 (

- 2.1, 0.34)

- 44.0 (

- 105, 17.2) b

Kinney et al. (1996 ) Pooled analysis of preceding 6 studies 616 campers without asthma ages 7

- 17 yr, 4,222 0.31 (

- 0.88, 1.5) 6.8 (

- 19.1, 32.7) b

Thurston et al. (1997 ) CT River Valley, CT 166 campers with asthma ages 7

- 13 yr, 5,333 - 2.8 (

- 4.9,

- 0.59)

- 146.7 (

- 261.7,

- 31.7)

Neas et al. (1999 ) Philadelphia, PA 156 campers without asthma ages 6

- 11 yr, 4,717 - 0.58 (

- 1.5, 0.33)

- 27.5 (

- 70.8, 15.8)

Berry et al. (1991 ) Hamilton, NJ 14 campers without asthma 58% age <14 yr, NA NA

- 40.4 (

- 132.1, 51.3)

*Includes studies form Figure 6

- 3

. NA = Data not available.

a All results are standardized to a 40

- ppb increase in 1

- h avg or 1

- h max O 3 , except that from Neas et al. (1999 ) , which is standardized to a 30

- ppb increase in 12

- h avg (9 a.m.

- 9 p.m.) O 3 . b Effect estimates were reported in the pooled analysis by Kinney et al. (1996 )

.

### Draft

– Do Not Cite or Quote 6

- 34 June 2012 Similar to controlled human exposure studies, camp studies found interindividual 

### 1 variability in the magnitude of O 3 - associated changes in lung function. Based on separate 

### 2 regression analyses of data from individual subjects, increases in ambient O 3 

### 3 concentration were associated with a wide range of changes in lung function across 

### 4 subjects ( Berry et al., 1991 ; Higgins et al., 1990 ; Spektor et al., 1988a ) . For example, 

### 5 among children attending camp in Fairview Lake, NJ, 36% of subjects had statistically 

### 6 significa nt O 3 - associated decreases in FEV 1 , and the 90th percentile of response was a 

### 7 6.3% decrease in FEV 1 per a 40

- pbb increase in 1

- h avg O 3 ( Spektor et al., 1988a )

. 

### 8

In contrast with previous studies, a recent study of children attending six different 

### 9 summer camps in Belgium did not find an association between ambient O 3 concentration 

### 10 and lung func tion ( Nickmilder et al., 2007 ) . This study examined similar ambient O 3 

### 11 concentrations as did previous studies ( Table 6

- 2 ) but used a less rigorous methodo logy. 

### 12 Lung function was measured only once in each subject, and mean lung function was 

### 13 compared among camps. Children at camps with higher daily 1

- h max or 8

- h max O 3 

### 14 concentrations did not consistently have larger decreases in mean intraday FEV 1 or 

### 15
FEV 1 /F VC ( Nickmilder et al., 2007 )

. 

### 16

Populations Exercising Outdoors

As discussed in the 1996 and 2006 O 3 AQCDs, epidemiologic studies of adults exercising 

### 17 outdoors have provided evidence for lung function decrements in healthy adults 

### 18
associated with increases in ambient O 3 exposure during exercise with durations (10 min 

### 19 to 12 h) and intensities (heart rates 121

- 190 beats per min) in the range of those examined 

### 20 in controlled human exposure studies ( Table 6

- 1 ). As in the camp studies, lung function 

### 21 was measured before and after exercise by trained staff. Collectively, studies of adults 

### 22
found FEV 1 decrements of 1.3 to 1.5% per unit increase in O 3 1 ( Figure 6

- 4 and 

### 23
Table 6

- 4 ). The magnitude of association did not appear to be related to study mean 

### 24
ambient O 3 concentrations ( Table 6

- 2 ), exercise duration, or the mean heart rate 

### 25 measured during exercise ( Figure 6

- 4 and Table 6

- 4 ). Increases in ambient O 3 

### 26
concentration also were associated with decre ases in lung function in children exercising 

### 27 outdoors ( Table 6

- 4 ). 

### 28

1 Effect estimates were standardized to a 40

- ppb increase in O 3 averaged over 15 min to 1 h and a 30

- ppb increase for O 3 averaged over 2 to 12 h.

### Draft

– Do Not Cite or Quote 6

- 35 June 2012 Note: Studies generally are presented in order of increasing duration of outdoor exercise. Data refer to the maximum or mean measured during exercise or in different groups or conditions as described in Table 6

- 4.

a bpm = beats per minute. NR = Not reported. Effect estimates are from single

- pollutant models and are standardized to a 4 0

- ppb increase for O 3 concentrations averaged over 15 minutes to 1 hour and a 30

- ppb increase for O 3 concentrations averaged over 2 to 12 hours.


### Figure 6

- 4 Percent change in FEV 1 

### in association with ambient ozone concentrations among adults exercising outdoors. Study

Korrick et al. (1998) Girardot et al. (2006) Hoppe et al. (2003) Spektor et al. (1988b) Brunekreef et al. (1994) Population

Adults hiking Adults hiking Adults exercising Adults exercising Adults exercising Exercise duration

2

- 12 h 2

- 9 h 2 h 15

- 55 min 10 min

- 1 h Mean heart rate (bpm) a

max: 122 max: 121 NR 162, 145 161, 176

- 4

- 3

- 2

- 1 0 1 2 Percent change in FEV 1 per unit increase in O 3 (95% CI)

### Draft

– Do Not Cite or Quote 6

- 36 June 2012 Table 6

- 4 Additional characteristics and quantitative data for studies represented in Figure 6

- 4 plus results from studies in children exercising outdoors.

Study * Location Population Exercise Duration, Mean Heart Rate O 3 Averaging Time Parameter Standardized Percent Change (95% CI) a

Studies of adults

Brunekreef et al. (1994 ) Netherlands 29 adults exercising, ages 18

- 37 yr 10 min

- 2.4 h, HR: 161 bpm (training), 176 bpm (races) Exercise duration FEV 1 PEF - 1.3 (

- 2.2,

- 0.37)

- 2.5 (

- 3.8,

- 1.2)

Spektor et al. (1988b ) Tuxedo, NY 30 adults exercising, ages 21

- 44 yr 15

- 55 min, HR:162 bpm if V ̇ E >100 L, 145 bpm if
V ̇ E 60

- 100 L 30

- min avg FEV 1 - 1.31 (

- 2.0,

- 0.65)

Hoppe et al. (2003 ) Munich, Germany 43 adults and children exercising, ages 13

- 38 yr 2 h, HR: NR 30

- min max (1

- 4 p.m.) FEV 1 PEF - 1.3 (

- 2.6, 0.10)

- 2.8 (

- 5.9, 0.31)

Girardot et al. (2006 ) Great Smoky Mt, TN 354 adult day hikers, ages 18

- 82 yr 2

- 9 h, max HR:121 bpm Hike duration FEV 1 PEF 0.72 (

- 0.46, 1.90) 3.5 (

- 0.11, 7.2)

Korrick et al. (1998 ) Mt. Washington, NH 530 adult day hikers, ages 18

- 64 yr 2

- 12 h, max HR: 122 bpm Hike duration FEV 1 PEF - 1.5 (

- 2.8,

- 0.24)

- 0.54 (

- 4.0, 2.9)

Selwyn et al. (1985 ) Houston, TX 24 adults exercising, ages 29

- 47 yr Duration: NR, max HR: 179 bpm in males, 183 bpm in females 15

- min max FEV 1 - 16 mL (

- 28.8,

- 3.2) b

Studies of children not included in Figure 6

- 4

Braun

Fahrlander et al. (1994 ) Switzerland 128 children exercising, ages 9

- 11 yr 10 min, max HR: 180 bpm 30

- min avg PEF

- 3.8 (

- 6.7,

- 0.96)

Castillejos et al. (1995 ) Mexico City, Mexico 40 children exercising, ages 7

- 11 yr 2 15 min with 15 min rest periods, max HR: <190 bpm 1

- h avg over full exerci se
- rest period FEV 1 - 0.48 (

- 0.72,

- 0.24)

Hoek et al. (1993 ) Wageningen, Netherlands 65 children exercising, ages 7

- 12 yr 25 min

- 1.5 h, HR: NR 1

- h max PEF

- 2.2 (

- 4.9, 0.54)

*Includes studies from Figure 6

- 4 , plus others.

HR = heart rate, bpm = beats per minute, V ̇ E = minute ventilation, NR = Not reported.

a Effect estimates are standardized to a 40

- ppb increase for O 3 concentrations averaged over 15 minutes to 1 hour and a 30

- ppb increase for O 3 concentrations averaged over 2 to 12 hours.

b Results not included in the figure because data were not provided to calculate percent change in lung function.

Compared with the studies of individuals exercising outdoors described above, analyses 

### 1 of day

- hikers assessed lung function only on one day per subjects but examined longer 

### 2 periods of outdoor activity and included much larger sample sizes. Studies of adult day



### 3 hikers had similar design but produced contrasting results ( Girardot et al., 2006 ; Korrick 

### 4 et al., 1998 ) . Among 530 hikers on Mt. Washington, NH, Korrick et al. (1998 ) reported 

### 5

### Draft

– Do Not Cite or Quote 6

- 37 June 2012 posthike declines in FEV 1 and FVC of 1.5% and 1.3%, respectively, per a 30

- ppb 

### 1
increase in 2

- to 12

- h avg O 3 . Associations with FEV 1 /FVC, FEF 25

- 75% , and PEF were 

### 2 weaker. In contrast, among 354 hikers on Great Smoky Mt, TN, Girardot et al. (2006 ) 

### 3 found that higher O 3 concentrations were associated with posthike increases in many of 

### 4 the same lung function indices ( Figure 6

- 4 and Table 6

- 4 ). These studies were similar in 

### 5 the examination of a mostly w hite, healthy population and of changes in lung function 

### 6
associated with ambient O 3 concentrations measured on site during multihour (2

- 12 h) 

### 7 periods of outdoor exercise. Mean O 3 concentrations were similar as were the population 

### 8 mean and variability in lu ng function. However, Girardot et al. (2006 ) differed from 

### 9 Korrick et al. (1998 ) in several aspects, including a shorter hike time ( maximum: 9 versus 

### 10
12 h) , older age of subjects (maximum: 82 versus 64 yr), and measurement of lung 

### 11 function by a larger number of less well

- trained technicians . The impact of these 

### 12 differences on the heterogeneity in results between the studies was not examined. 

### 13

Similar to the camp studies, some studies of outdoor exercise examined and found 

### 14 interindividual variability in the magnitude of O 3 - associated decrease s in lung function. 

### 15
In Korrick et al. (1998 ) , although a 30

- ppb increase in 2

- to 12

- h avg ambient O 3 

### 16 concentration was associated with a group mean decrement in FEF 25

- 75% o f

- 0.81% 

### 17 (95% CI:

- 4.9, 3.3), some individuals experienced a >10% decline. The odds of >10% 

### 18
decline in FEF 25

- 75% increased with increasing ambient O 3 concentration (OR: 2.3 

### 19 [95% CI: 1.2, 6.7] per 30

- ppb increase in 2

- to 12

- h avg O 3 ). Likewise, Hoppe et al. 

### 20 (2003 ) found that compared with days with 30

- min max (1

- 4 p.m.) ambient O 3 

### 21
concentrations <40 ppb, on days with O 3 >50 ppb, 14% of athlet es had at least a 10% 

### 22 decrease in lung function or 20% increase in airway resistance. 

### 23

Outdoor Workers

Consistent findings in outdoor workers add to the evidence that short

- term increases in 

### 24
ambient O 3 exposure decrease lung function in healthy adults ( Figure 6

- 5 and Table 6

- 5 ). 

### 25 Except for Hoppe et al. (1995 ) , studies used central site ambient O 3 concentrations. 

### 26 However, in outdoor workers, ambient concentrations have been more highly correlated 

### 27 with and similar in magnitude to personal exposures (Section 4.3.3 ) likely because 

### 28 workers spend long periods of time outdoors (6

- 14 hours across studies) and the O 3 

### 29 averaging times examined correspond to periods of outdoor work . For example, in a 

### 30 subset of berry pickers, the correlation and ratio of personal to ambient 24

- h avg O 3 

### 31 concentrations (15 km from work site) were 0.64 and 0.96, respectively ( Brauer and 

### 32 Brook, 1997 ) . The 6

- h avg personal

- ambient ratio in a population of shoe cleaners in 

### 33 Mexico City was 0.56 ( O'Neill et al., 2003 ) . Many studies of outdoor workers found that 

### 34
in addition to same

- day concentrations, O 3 concentration s lagged 1 or 2 days ( Chan and 

### 35

### Draft

– Do Not Cite or Quote 6

- 38 June 2012 Wu, 2005 ; Brauer et al., 1996 ) or averaged over 2 days ( Romieu et al., 1998b ) were 

### 1 associated with equal or larger decrements in lung function ( Figure 6

- 5 and Table 6

- 5 ). 

### 2

Similar to other po pulations with increased outdoor exposure, most of the magnitudes of 

### 3
O 3 - associated lung function decrements in outdoor workers were small, i.e., <1% to 3.4% 

### 4 per unit increase in O 3 concentration 1 . The magnitude of decrease was not found to 

### 5 depend strongly on duration of outdoor work or ambient O 3 concentration. The largest 

### 6 decrease (6.4% per 40

- ppb increase in 1

- h max O 3 ) was observed in berry pickers in 

### 7 British Columbia who were examined during a period of relatively low ambient O 3 

### 8 concentrations (work shi ft mean: 26.0 ppb [SD: 11.8]) but had longer daily periods of 

### 9 outdoor work (8

- 14 hours) ( Brauer et al., 1996 ) ( Figure 6

- 5 and Table 6

- 5 ). However, a 

### 10
much smaller O 3 - associated decrease in FEV 1 was found in shoe cleaners in Mexico City 

### 11 who were examined during a period of higher O 3 concentrations (work shift mean: 

### 12
67.3 ppb [SD: 24]) but had period of outdoor work that was as long as that of the berry 

### 13 pickers. The smallest magnitude of decrease (

- 0.4% [95% CI:

- 0.8, 0] in afternoon 

### 14
FEV 1 /FVC per 40

- ppb increase in 1

- h max O 3 ) was observed in lifeguards in Galveston, 

### 15
TX ( Thaller et al., 2008 ) whose outdoor work periods were shorter than those of the berry 

### 16 pickers but characterized by a similar range of ambient O 3 concentrations. Not all studies 

### 17 provided information on ventilation rate or pulse rate, thus it was not possible to ascertain 

### 18
wh ether differences in the magnitude of O 3 - associated lung function decrement across 

### 19
studies were related to differences in the level of exertion of workers. 

### 20

1 Effect estimates were standardized to a 40

- ppb increase for O 3 averaged over 30 min to 1 h and a 30

- ppb increase for O 3 averaged over 8 or 12 h.

### Draft

– Do Not Cite or Quote 6

- 39 June 2012 Note: Studies generally are presented in order of increasing mean ambient O 3 concentration. Effect estimates are from single

pollutant models and are standardized to a 40

- ppb increase for 30

- min, 1

- h avg, or 1

- h max O 3 concentrations.


### Figure 6

- 5 Percent change in FEV 1 

### or FEV 1 

### /FVC in association with ambie nt ozone concentrations among outdoor workers. Study

Thaller et al. (2008)

Brauer et al. (1996)

Hoppe et al. (1995)

Romieu et al. (1998) Population

Lifeguards

Berry pickers

Forestry workers

Shoe Cleaners Parameter

FVC
FEV 1 /FVC

FEV 1

FEV 1

FEV 1 O 3 Lag

0

0
1

0

0

0

- 1 avg Subgroup

Placebo Antioxidant supplement
Placebo Antioxidant supplement

- 8

- 7

- 6

- 5

- 4

- 3

- 2

- 1 0 1 2 Percent change in lung function per unit increase in O 3 (95% CI)

### Draft

– Do Not Cite or Quote 6

- 40 June 2012 Table 6

- 5 Additional characteristics and quantitative data for studies represented in Figure 6

- 5.

Study * Location Population Parameter Duration of Outdoor

Work O 3 Averaging Time O 3 Lag Subgroup Standardized Percent Change (95% CI) a

Thaller et al. (2008 ) Galveston, TX 142 lifeguards, ages 16

- 27 yr FVC 6

- 8 h 1

- h max 12

- h avg 0 0.24 (

- 0.28, 0.72) 0.15 (

- 0.06, 0.36)

FEV 1 /FVC 1

- h max 12

- h avg - 0.40 (

- 0.80, 0)

- 0.60 (

- 1.2, 0)

Brauer et al. (1996 ) British Columbia, Canada 58 berry pickers, ages 10

- 69 yr FEV 1 8

- 14 h 1

- h max 0
1 - 5.4 (

- 6.5,

- 4.3)

- 6.4 (

- 8.0,

- 4.7)

Hoppe et al. (1995 ) Munich, Germany 41 forestry workers, ages 20

- 60 yr FEV 1 Not reported 30

- min max (1

- 4 p.m.) 0

- 1.4 (

- 3.0, 0.16)

Romieu et al. (1998b ) Mexico City, Mexico 47 male shoe cleaners, mean (SD) age: 38.9 (10) yr FEV 1 Mean (SD): 9 h (1) 1

- h avg before lung function measurement 0 Placebo Antioxidant - 2.1 (

- 3.3,

- 0.85)

- 0.52 (

- 2.0, 0.97)

0

- 1 avg Placebo Antioxidant - 3.4 (

- 6.0,

- 0.78)

- 1.2 (

- 4.2, 1.8)

Chan and Wu (2005 ) b Taichung City, Taiwan 43 mail carriers. Mean (SD) age: 39 (8) yr PEF 8 h 1

- h max 0 1 - 1.3 (

- 1.7,

- 0.92)

- 1.4 (

- 1.7,

- 1.2)

8

- h avg (9 a.m.
- 5 p.m.) 0 1 - 1.6 (

- 2.2,

- 1.1)

- 1.9 (

- 2.5,

- 1.3)

*Includes studies from Figure 6

- 5 , plus others.

a Effect estimates are standardized to a 40

- ppb increase for 30

- min, 1

- h avg, or 1

- h max O 3 and a 30

- ppb increase for 8

- h avg or 12

- h avg O 3 . b PEF results not included in figure.

Associations at Lower Ozone Concentrations

In some studies of populations with increased outdoor exposures, O 3 - associated lung 

### 1 function decrements were observed when maximum or average ambient O 3 

### 2
concentrations over 30 minutes to 12 hours did not exceed 80 ppb ( Chan and Wu, 2005 ; 

### 3 Korrick et al., 1998 ; Hoppe et al., 1995 ; Braun

- Fahrlander et al., 1994 ) (presented within 

### 4
Table 6

- 2 ). Korrick et al. (1998 ) found associations between hike

- time average (2

- 12 h) 

### 5
O 3 concentrations and lung function between concentrations 40 and 74 ppb but not 

### 6
<40 ppb. Several other studies that included higher maximum ambient O 3 concentrations 

### 7 restricted analyses to observations with 10

- min to 1

- hour average O 3 concentrations 

### 8

< 80 ppb ( Table 6

- 6 ). Higgins et al. (1990 ) found that O 3 - associated lung function 

### 9 decrements in children attending camp were limited largely to 1

- h avg ambient 

### 10
concentrations >120 ppb; however, many other studies found associations in the lower 

### 11 range of O 3 concentrations ( Table 6

- 6 ). Among adults exercising outdoors, Spektor et al. 

### 12

### Draft

– Do Not Cite or Quote 6

- 41 June 2012 (1988b ) found that for most lung function parameters, effect est imates in analyses 

### 1
restricted to 30

- min max ambient O 3 concentrations <80 ppb were similar to those 

### 2 obtained for the full range of O 3 concentrations ( Table 6

- 6 ). In a study of children 

### 3 attending summer camp, similar effects were estimated for the full range of 1

- h avg O 3 

### 4
concentrations and those <60 ppb ( Spektor et al., 1988a )

. Brunekreef et al. (1994 ) found 

### 5
increases in ambient O 3 concentration (10

- min to 1

- h) during outdoor exercise to be 

### 6
associated with decreases in FEV 1 in analyses restricted to concentrations <61 

### 7 ( Table 6

- 6 ) and <51 ppb (quantitative results not reported). Whereas Brunekreef et al. 

### 8 (1994 ) found that effect estimates were near zero with O 3 concentrations <41 ppb 

### 9 ( Brunekreef et al., 1994 )
, Brauer et al. (1996 ) found that associations persisted with 

### 10
1

- h max O 3 concentrations <40 ppb (quantitative results not provided). 

### 11

Table 6

- 6 Associations between ambient ozone concentration and FEV 1 

### decrements in different ranges of ambient ozone concentrations.

Study Location Population O 3 Averaging Time O 3 Concentration Range Standardized Percent Change (95% CI) a

Brunekreef et al. (1994 ) Netherlands 29 adults exercising, ages 18

- 37 yr 10

- min to 1

- hour average during exercise Full range O 3 <61 ppb - 1.3 (

- 2.2,

- 0.37)

- 2.1 (

- 4.5, 0.32)

Spektor et al. (1988a ) Fairview Lake, NJ 91 children without asthma at camp, ages 8

- 15 yr 1

- hour average before afternoon FEV 1 measurement Full range O 3 <60 ppb O 3 <80 ppb - 2.7 (

- 3.3,

- 2.0)

- 2.2 (

- 3.7,

- 0.80)

- 1.4 (

- 2.5,

- 0.34) Spektor et al. (1988b ) Tuxedo, NY 30 adults exercising, ages 21

- 44 yr 30

- min average during exercise Full range O 3 <80 ppb - 1.3 (

- 2.0,

- 0.64)

- 1.3 (

- 2.4,

- 0.08)

1998 ) Mt. Washington, NH 53 adult day hikers, ages 18

- 64 yr Hike duration (2

- 12 h) Full range O 3 40

- 74 ppb - 1.5 (

- 2.8,

- 0.24)

- 2.6 (

- 4.9,

- 0.32)

Higgins et al. (1990 ) San Bernardino, CA 43 children without asthma at camp, ages 7

- 13 yr 1

- hour average in the 6

- hours before FEV 1 measurement >120 ppb <120 ppb - 1.4 (

- 2.8, 0.03) 0.34 (

- 1.3, 2.0)

a Results are presented in order of increasing maximum O 3 concentration included in models. Effect estimates are standardized to a 40

- ppb increase for O 3 concentrations averaged over 10 min to 1 h and a 30

- ppb increase for O 3 co ncentrations averaged over 2 to 12 h.

Children with Asthma

Increases in ambient O 3 concentration are associated with lung function decrements in 

### 12 children with asthma in epidemiologic studies conducted across diverse geographical 

### 13 locations and a range of ambient O 3 concentrations ( Table 6

- 7 ). Whereas most studies of 

### 14 populations with increased outdoor exposures monitored O 3 concentrations at the site of 

### 15 subjects’ outdoor activities and used trained staff to measure lung function, studi es of 

### 16

### Draft

– Do Not Cite or Quote 6

- 42 June 2012 children with asthma relied more on O 3 measured at central monitoring sites and lung 

### 1 function measured by subjects. Nonetheless, compared with the camp studies, studies of 

### 2 children with asthma have provided an understanding of the changes in lung fun ction 

### 3 associated with patterns of outdoor activity and ambient O 3 exposure that likely better 

### 4 represent those of children in the general population. Further, these studies have provided 

### 5 more information on factors that potentially may increase the risk of O 3 - associated 

### 6 respiratory effects and on potential confounding by copollutant exposure or meteorology. 

### 7

Table 6

- 7 Mean and upper percentile concentrations of ozone in epidemiologic studies of lung f unction in c hildren with asthma

. Study * Location Study Period O 3 Averaging Time Mean/Median Concentration (ppb) Upper Percentile Concentrations (ppb)

Jalaludin et al. (2000 ) Sydney, Australia February

December 1994 15

- h avg (6 a.m.
- 9 p.m.) 12 Max: 43

1

- h max 26 91

Lewis et al. (2005 ) Detroit, MI February 2001

- May 2002 24

- h avg 8

- h max 27.6, 26.5 a 40.4, 41.4 a Overall max: 66.3 a Overall max: 92.0 a
Just et al. (2002 ) Paris, France April

- June 1996 24

- h avg 30.0 b Max: 61.7 b
Hoppe et al. (2003 ) Munich, Germany Summers 1992

- 1995 30

- min max (1

- 4 p.m.) High O 3 days: 66.9 c Control O 3 days: 32.5 c Max: 91 (high O 3 days) c 39 (control O 3 days) c

Thurston et al. (1997 ) CT River Valley, CT June 1991

- 1993 1

- h max 83.6 c Max: 160 c

Romieu et al. (2006 ); ( 2004b ; 2002 ) Mexico City, Mexico October 1998

- April 2000 8

- h max 1

- h max 69 102 Max: 184 Max: 309

Romieu et al. (1997 ) Southern Mexico City, Mexico April

- July 1991; November 1991

- February 1992 1

- h max 196 Max: 390

Romieu et al. (1996 ) Northern Mexico City, Mexico Ap ril

- July 1991; November 1991

- February 1992 1

- h max 190 Max: 370

O'Connor et al. (2008 ) Boston, MA; Bronx, Manhattan NY; Chicago, IL; Dallas, TX, Seattle, WA; Tucson, AZ (ICAS) August 1998

- July 2001 24

- h avg NR NR

Mortimer et al. (2002 ) ( 2000 ) Bronx, East Harlem, NY; Baltimore, MD; Washington, DC; Detroit, MI, Cleveland, OH; Chicago, IL; St. Louis, MO (NCICAS) June

- August 1993 8

- h avg (10 a.m.
- 6

p.m.) 48 NR

Gielen et al. (1997 ) Amsterdam, Nether lands April

- July 1995 8

- h max 34.2 b Max: 56.5 b

### Draft

– Do Not Cite or Quote 6

- 43 June 2012 Study * Location Study Period O 3 Averaging Time Mean/Median Concentration (ppb) Upper Percentile Concentrations (ppb)

Dales et al. (2009 ) ( 2009a ) Windsor, ON, Canada October

December 2005 24

- h avg 1

- h max 13.0 27.2 75th: 26.0 75th: 32.8

Rabinovitch et al. (2004 ) Denver, CO November

March 1999

- 2002 1

- h max 28.2 75th: 36.0, Max 70.0

Barraza

- Villarreal et al. (2008 ) Mexico City, Mexico June 2003

- Ju ne 2005 8

- h moving avg 31.6 Max: 86.3

Wiwatanadate and Trakultivakorn (2010 ) Chiang Mai, Thailand August 2005

- June 2 006 24

- h avg 17.5 90th: 26.82, Max: 34.65

Delfino et al. (2004 ) Alpine, CA September

October 1999; April

- June 2000 8

- h max 62.9 90th: 83.9, Max: 105.9

Hernández

Cadena et al. (2009 ) Mexico City, Mexico May

- September 2005 24

- h avg 1

- h max 26.3 74.5 75th: 35.3; Max: 62.8 75th: 92.5; Max: 165

* Note: Studies presented in order of first appearance in the text of this section. ICAS = Inner City Asthma Study, NR = Not Reported, NCICAS = National Cooperative Inner

- City Asthma Study.

a Measurements at two sites established by investigators and located within 5 km of most subjects’ residences.

b Concentrations converted from μg/m 3 to ppb using the conversion factor of 0.51 assuming standard temperature (25°C) and pressure (1 atm).

c Measured where subjects spent daytime hours.

In a majority of studies, including large U.S. multicity studies and several smaller studies 

### 1 conducted in the U.S., Mexico City, and Europe, an increase in ambient O 3 concentration 

### 2 (various averaging times and lags) was assoc iated with a decrement in FEV 1 ( Figure 6

- 6 

### 3
and Table 6

- 8 ) or PEF ( Figure 6

- 7 and Table 6

- 9 ) in children with asthma. Results were 

### 4
more variable for FEV 1 , which typically was measured on nonconsecutive days, than for 

### 5 PEF, which was measured daily. Further, associations with FEV 1 were found in specific 

### 6 subgroups. Some studies found that increases in ambient O 3 concentration were 

### 7 associated with greater lung function variability, i.e., a deviation from a baseline level. 

### 8 These results pointed to associations of O 3 with poorer lung f unction, as indicated by a 

### 9 decrease from the individual’s mean lung function over the study period ( Jalaludin et al., 

### 10
2000 ) , a decrease in lung function over the course of the day ( Lewis et al., 2005 ) , or a 

### 11 decrease in the lowest daily measurement ( Just et al., 2002 ) . Within many studies, 

### 12
increases in O 3 concent ration were associated concurrently (at the same or similar lag) 

### 13 with decreases in lung function and increases in respiratory symptoms ( Just et al., 2002 ; 

### 14 Mortimer et al., 2002 ; Gielen et al., 1997 ; Romieu et al., 1997 ; Thurston et al., 1997 ; 

### 15 Romieu et al., 1996 ) (see Figure 6

- 11 and Table 6

- 20 for symptom results). 

### 16

### Draft

– Do Not Cite or Quote 6

- 44 June 2012 Note: Results generally are presented in order of increasing mean ambient O 3 concentration. CS = Corticosteroid, URI = Upper respiratory inf ection. Effect estimates are from single

- pollutant models and are standardized to a 40

- ppb increase for 30

- min or 1

- h max O 3 concentrations, a 30

- ppb increase for 8

- h max or 8

- h avg O 3 concentrations, and a 20

- ppb increase for 24

- h avg O 3 concentrations.


### Figure 6

- 6 Percent change in FEV 1 

### in association with ambient ozone concentrations among children with asthma. Study

Liu et al. (2009)

Lewis et al. (2005)

Hoppe et al. (2003)

Barraza

- Villarreal et al. (2008)

Romieu et al. (2002)

Romieu et al. (2006) O 3 Lag

0
1

1

1

0

- 4 avg

1

1 Subgroup

CS user
With URI

Without asthma
With asthma

Without asthma
With asthma

Placebo
Antioxidant
Placebo
Antioxidant

GSTP1 Ile/Ile or Ile/Val
GSTP1 Val/Val , moderate/severe

, moderate/severe asthma

asthma

◄ ►

- 10

- 8

- 6

- 4

- 2 0 2 4

Percent change in FEV 1 per unit increase in O 3 (95% CI)

### Draft

– Do Not Cite or Quote 6

- 45 June 2012 Table 6

- 8 Characteristics and quantitative data for studies represented in Figure 6

- 6, of FEV 1 

### or FVC in children with asthma.
Study * Location/Population O 3 Averaging Time O 3 Lag Parameter Subgroup Standardize d Percent Change (95% CI) a

Liu et al. (2009a ) Windsor, ON, Canada 182 children with asthma, ages 9

- 14 yr 24

- h avg 0 1 FEV 1 - 0.89 (

- 3.5, 1.8)

- 0.44 (

- 2.4, 1.6)

Lewis et al. (2005 ) Detroit, MI 86 children with asthma,
mean (SD) age 9.1 (1.4) yr 8

- h max 1 Lowest daily FEV 1 CS user With URI - 2.1 (

- 11.4, 8.3)

- 6.1 (

- 10.4,

- 1.6)

2 CS user With URI - 8.0 (

- 13.5,

- 2.1)

- 5.4 (

- 11.3, 1.0) Hoppe et al. (2003 ) Munich, Germany 43 children, ages 12

- 23 yr 30

- min max (1

- 4 p.m.) 1 Afternoon FEV 1 Without asthma With asthma 0.93 (

- 0.80, 2.7)

- 0.56 (

- 4.6, 3.7)

Afternoon FVC Without asthma With asthma - 0.09 (

- 1.7, 1.6)

- 3.5 (

- 5.9,

- 1.0)

Barraza

Villarreal et al. (2008 ) Mexico City, Mexico 208 children, ages 6

- 14 yr 8

- h avg 0

- 4 avg FEV 1 50 without asthma 158 with asthma - 1.5 (

- 4.7, 1.7)

- 0.12 (

- 2.0, 1 .8)

Romieu et al. (2002 ) Mexico City, Mexico 158 child ren with asthma, ages 6

- 17 yr 1

- h max 1 FEV 1 Placebo

- 0.21 (

- 0.77, 0.36) Antioxidant supplement 0.05 (

- 0.60, 0.69)
Placebo, moderate/severe asthma - 1.1 (

- 2.0,

- 0.19)

Antioxidant supplement, moderate/severe asthma - 0.04 (

- 0.92, 0.83)

Romieu et al. (2006 ) Mexico City, Mexico 151 children with asthma,
mean age 9 yr 1

- h max 1 FEV 1 GSTP1 Ile/Ile or Ile/Val GSTP1 Val/Val - 0.51 (

- 1.1, 0.05) 0.50 (

- 0.25, 1.3)

Studies not included in Figure 6

- 6 b

Dales et al. (2009 ) Windsor, ON, Canada 182 children with asthma, ages 9

- 14 yr 1

- h max 0 Evening percent predicted FEV 1 - 0.47 (

- 1.9, 0.95)

Rabinovitch et al. (2004 ) Denver, CO 86 children with asthma, ages 6

- 12 yr 1

- h max 0

- 2 avg Morning FEV 1 (mL) 55 (

- 2.4, 108)

O'Connor et al. (2008 ) Boston, MA; Bronx, Manhattan NY; Chicago, IL; Dallas, TX, Seattle, WA; Tu cson, AZ 861 children with asthma,
mean (SD) age 7.7 (2.0) yr 24

- h avg 1

- 5 avg Change in percent predicted FEV 1 - 0.41 (

- 1.0, 0.21)

*I ncludes studies in Figure 6

- 6 , plus others CS = corticosteroid, URI = Upper respiratory infection.

a Effect estimates are standardized to a 40

- ppb increase for 30

- min or 1

- h max O 3 , a 30

- ppb increase for 8

- h max or 8

- h av g O 3 , and a 20

- ppb increase for 24

- h avg O 3 . b Results not presented in Figure 6

- 6 because a different form of FEV 1 with a different scale was examined or because sufficient data were not provided to calculate percent change in FEV 1 .

### Draft

– Do Not Cite or Quote 6

- 46 June 2012 Note: Results generally are presented in order of increasing mean ambient O 3 concentration. BW = birth weight, CS = Corticosteroid. Effect estimates are from single pollutant models and are standardized to a 40

- ppb increase for 1

- h max O 3 concentrations and a 30

- ppb increase for 8

- h max or 8

- h avg O 3 concentrations.


### Figure 6

- 7 Percent change in PEF or FEF 25

- 75% 

### in associ ation with ambient ozone concentrations among children with asthma. Study
Gielen et al. (1997)

Mortimer et al. (2002)

Mortimer et al. (2000)

Thurston et al. (1997)

Romieu et al. (2004a)

Romieu et al. (1996)

Romieu et al. (1997) Parameter
Evening PEF

Morning PEF

Morning PEF

Morning PEF

PEF

FEF 25

- 75%

Evening PEF

Evening PEF O 3 Lag

0 2 2

1 3 1

- 5 avg

0

1

0 2

0 2 Subgroup

All subjects Normal BW Low BW No asthma medication CS user

Placebo, GSTM1 null Placebo, GSTM1 positive Antioxidant, GSTM1 null Antioxidant, GSTM1 positive

- 10

- 8

- 6

- 4

- 2 0 2 4 Percent change in PEF or FEF 25

- 75%

per unit increase in O 3 (95% CI)

### Draft

– Do Not Cite or Quote 6

- 47 June 2012 Table 6

- 9 Characteristics and quantitative data for studies represented in Figure 6

- 7, of PEF or FEF 25

- 75% 

### in children with asthma.

Study * L ocation/Population O 3 Averaging Time O 3 Lag Parameter Subgroup Standardized Percent Change (95% CI) a

Gielen et al. (1997 ) Amsterdam, Netherlands 61 children with asthma, ages 7

- 13 yr 8

- h max 0 2 2 Evening PEF Evening PEF Morning PEF - 1.3 (

- 0.25, 2.9)

- 1.3 (

- 2.8, 0.16)

- 1.3 (

- 2.6,

- 0.08)

Mortimer et al. (2002 ) Bronx, East Harlem, NY; Baltimore, MD; Washington, DC; Detroit
, MI, Cleveland, OH; Chicago, IL; St. Louis, MO 846 children with asthma, ages 4

- 9 yr 8

- h avg (10 a.m.

- 6 p.m.) 1 3
1

- 5 avg Morning PEF All subjects

- 0.12 (

- 0.76, 0.52)

- 0.64 (

- 1.2,

- 0.10)

- 1.2 (

- 2.1,

- 0.26)

Mortimer et al. (2000 ) Bronx, East Harlem, NY; Baltimore, MD; Washington, DC; Detroit, MI, Cleveland, OH; Chicago, IL; St. Louis, MO 846 children with asthma, ages 4

- 9 yr 8

- h avg (10 a.m.

- 6 p.m.) 1

- 5 avg Morning PEF Normal BW Low BW (<5.5 lbs.) No medication CS user - 0.60 (

- 1.6, 0.39)

- 3.6 (

- 5.2,

- 2.0)

- 1.1 (

- 3.0, 0.84)

- 1.2 (

- 2.5, 0.11)

Thurston et al. (1997 ) CT River Valley, CT 166 children with asthma, ages 7

- 13 yr 1

- h max 0 Intraday change PEF - 2.8 (

- 4.9,

- 0. 59)

Romieu et al. (2004b ) Mexico City, Mexico 158 children with asthma,
mean age 9 yr 1

- h max 1 FEF 25

- 75% Placebo, GSTM1 null Placebo, GSTM1 positive Antioxidant, GSTM1 null Antioxidant, GSTM1 positive - 2.3 (

- 4.2,

- 0.44)

- 0.48 (

- 1.7, 0.74)

- 0.16 (

- 1.8, 1.6) 0.24 (

- 1.3, 1.8)

Romieu et al. (1996 ) Northern Mexico City, Mexico 71 children with asthma, ages 5

- 7 yr 1

- h max 0 2 Evening PEF

- 0.17 (

- 0.79, 0.46)

- 0.55 (

- 1.3, 0.19)

Romieu et al. (1997 ) Southern Mexico City, Mexico 65 children with asthma, ages 5

- 13 yr 1

- h max 0 2 Evening PEF

- 0.52 (

- 1.0,

- 0.01)

- 0.06 (

- 0.70, 0.58)

### Draft

– Do Not Cite or Quote 6

- 48 June 2012 Study * L ocation/Population O 3 Averaging Time O 3 Lag Parameter Subgroup Standardized Percent Change (95% CI) a
Studies not included in Figure 6

- 7 b

Jalaludin et al. (2000 ) Sydney , Australia 20 children with asthma and AHR, mean (SD) age 9.6 (0.9) yr 24

- h avg 1

- h max 0 Daily deviation from mean PEF - 2.4 (

- 5.1, 0.28) c

- 1.3 (

- 2.8, 0.17) c

Wiwatanadate and Trakultivakorn (2010 ) Chiang Mai, Thailand 31 children with asthma, ages 4

- 11 yr 24

- h avg 0
5 Daily avg PEF (L/min) 1.0 (

- 1.6, 3.6)

- 2.6 (

- 5.2, 0)

O'Connor et al. (2008 ) Boston, MA; Bronx, Manhattan NY; Chicago, IL; Dallas, TX, Seattle, WA; Tucson, AZ 861 Children with asthma,
mean (SD) age 7.7 (2.0) yr 24

- h avg 1

- 5 avg Change in percent predicted PEF - 0.22 (

- 0.86, 0.43)

Just et al. (2002 ) Paris, France 82 children with asthma,
mean (SD) age 10.9 (2.5) yr 8

- h avg 0

- 2 avg Percent variability PEF 15.6 (0, 31.2)

*I ncludes studies in Figure 6

- 7 , plus others BW = birth weight, CS = corticosteroid, AHR = Airway hyperresponsiveness.

a Effect estimates are standardized to a 40

- ppb increase for 1

- h max O 3 , a 30

- ppb increase for 8

- h max o r avg O 3 , and a 20

- ppb increase for 24

- h avg O 3 . b Results are not presented in Figure 6

- 7 because a different form of PEF with a different scale was ex amined or because sufficient data were not provided to calculate percent change in PEF.

c Outcome defined as the normalized percent deviation from individual mean PEF during the study period. Quantitative results fr om generalized estimating equations were provided only for models that included PM 10 and NO 2 .

The most geographically representative data were provided by the large, multi

- U.S. city 

### 1 National Cooperative Inner City Asthma Study (NCICAS) ( Mortimer et al., 2002 ; 2000 ) 

### 2
and Inner

- City Asthma Study (ICAS) ( O'Connor et al., 2008 ) . Although the two studies 

### 3
di ffered in the cities, seasons, racial distribution of subjects, and lung function indices 

### 4 examined, results were fairly similar. In ICAS, which included children with asthma and 

### 5 atopy (i.e., allergic sensitization) and year

- round examinations of lung funct ion, a 20

- ppb 

### 6 increase in the lag 1

- 5 average of 24

- h avg O 3 was associated with a 0.41

- point decrease 

### 7 in percent predicted FEV 1 (95% CI:

- 1.0, 0.21) and a 0.22

- point decrease in percent 

### 8 predicted PEF (95% CI:

- 0.86, 0.43) ( O'Connor et al., 2008 )

. 

### 9

Increases in lag 1

- 5 avg O 3 (8

- h avg, 10 a.m.

- 6 p.m.) also were associated with declines 

### 10 in PEF in NCICAS, which included different U.S. cities, summer

- only measurements, 

### 11 larger proportions of Black and Hispanic children, and fewer subjects with atopy (79%) 

### 12 ( Mortimer et al., 2002 ) . Ozone concentrations lagged 3 to 5 days were associated with 

### 13 larger PEF decrements than wer e O 3 concentrations lagged 1 to 2 days ( Figure 6

- 7 and 

### 14
Table 6

- 9 ). NCICAS additionally identified groups potentially at increased risk of 

### 15
O 3 - associated PEF decrements, namely, males, children of Hispanic ethnicity, children 

### 16 living in crowded housing, and as indicated in Figure 6

- 7 and Table 6

- 9 , children with 

### 17

### Draft

– Do Not Cite or Quote 6

- 4 9 June 2012 birth weight <5.5 lbs ( Mortimer et al., 2000 ) . Somewhat paradoxically, O 3 was associated 

### 1 with a larger decreas e in PEF among subjects taking cromolyn, medication typically used 

### 2 to treat asthma due to allergy, but a smaller decrease among subjects with positive atopy 

### 3 (as determined by skin prick test). NCICAS also indicated robust associations with 

### 4
consideration of other sources of heterogeneity. Except for Baltimore, MD, effect 

### 5 estimates were similar across the study cities (1.1 to 1.7% decrease in PEF per 30

- ppb 

### 6 increase in lag 1

- 5 avg of 8

- h avg O 3 ). Results were similar with O 3 averaged from all 

### 7 available city m onitors and concentrations averaged from the three monitors closest to 

### 8 subject ZIP code centroid (1.2% and 1.0%, respectively, per 30

- ppb increase in O 3 ). At 

### 9
concentrations <80 ppb, a 30

- ppb increase in lag 1

- 5 of 8

- h avg O 3 was associated with a 

### 10
1.4% decr ease (95% CI:

- 2.6,

- 0.21) in PEF, which was similar to the effect estimated for 

### 11 the full range of O 3 concentrations ( Figure 6

- 7 and Table 6

- 9 ). In a study of children with 

### 12 asthma in the Netherlands, Gielen et al. (1997 ) estimated similar effects for the full range 

### 13
of 8

- h max O 3 concentrations and concentrations <51 ppb. 

### 14

Several but not all controlled human exposure studies have reported slightly larger 

### 15
O 3 - induced FEV 1 decrements in adults with asthma (Section 6.2.1.1 ). However, in the 

### 16 few epidemi ologic studies that compared children with and without asthma, evidence did 

### 17 not conclusively indicate that children with asthma were at increased risk of 

### 18
O 3 - associated lung function decrements. Hoppe et al. (2003 ) and Jalaludin et al. (2000 ) 

### 19 generally found larger O 3 - associated lung function decrements in children with asthma; 

### 20
whereas Raizenne et al. (1989 ) did not consistently demonstrate differences between 

### 21 campers with and without asthma. In their study of children in Mexico City, Barraza



### 22 Villarreal et al. (2008 ) estimated larger O 3 - associated decreases in children without 

### 23 asthma; however, 72% of these children had atopy. These findings indicate that children 

### 24 with atopy, who also have airway inflammation and similar respiratory symptoms, may 

### 25 experience respiratory effects from short

- term ambient O 3 exposu re. 

### 26

As shown in Figure 6

- 6 and Figure 6

- 7 and Table 6

- 8 and Table 6

- 9 , lung function 

### 27 decrements in children with asthma mostly ranged from <1% to 2% per unit increase in 

### 28
ambient O 3 concentration 1 . Larger magnitudes of decrease , were found in children with 

### 29 asthma who were using CS, had a concurrent upper respiratory infection (URI), were 

### 30 GSTM1 null, had airway hyperresponsiveness, or had increased outdoor exposure 

### 31 ( Romieu et al., 2006 ; Lewis et al., 2005 ; Romieu et al., 2004b ; Jalaludin et al., 2000 ) than 

### 32 among children with asthma overall ( Barraza

- Villarreal et al., 2008 ; Lewis et al., 2005 ; 

### 33 Delfino et al., 2004 ; Romieu et al., 2002 ) . For example, Jalaludin et al. (2000 ) estimated a 

### 34

- 5.2% deviation from mean FEV 1 per a 20

- ppb increase in 24

- h avg O 3 concentrat ion 

### 35 among children with asthma and airway hyperresponsiveness and a much smaller

- 0.71% 

### 36

1 Effect estimates were standardized to a 40

- , 30

- , and 20

- ppb increase for 1

- h max, 8

- h max or avg, and 24

- h avg O 3 .

### Draft

– Do Not Cite or Quote 6

- 50 June 2012 deviation among children with asthma without airway hyperresponsiveness. In a group of 

### 1 86 children with asthma in Detroit, MI, Lewis et al. (2005 ) reported that a ssociations 

### 2
between ambient O 3 concentration and FEV 1 were confined largely to children with 

### 3 asthma who used CS or had a concurrent URI, 8.0% and 5.4% decreases, respectively, in 

### 4 the mean of lowest daily FEV 1 per 30

- ppb increase in 8

- h max ambient O 3 conce ntration. 

### 5

Heterogeneity in response to O 3 exposure also was demonstrated by observations that 

### 6 some individuals experienced larger O 3 - associated lung function decrements than the 

### 7 population mean effect estimate. Similar observations were made in controlled human 

### 8 exposure studies (Section 6.2.1.1 ). Mortimer et al. (2002 ) found that for a 30

- ppb 

### 9 increase in lag 1

- 5 avg of 8

- h avg O 3 , there was a 30% (95% CI: 4, 61) higher incidence 

### 10 of >10% decline in PEF. Likewise, Hoppe et al. (2003 ) found that while the percentages 

### 11 of lung function decrements were variable and small, 47% of children with asthma 

### 12 experienced >10% decline in FEV 1 , FVC, or PEF or 20% increase in airway resistance on 

### 13 days with 30

- min (1

- 4 p. m.) max ambient O 3 concentrations >50 ppb relative to days 

### 14
with <40 ppb O 3 . 

### 15

Effect modification by corticosteroid use

In controlled human exposure studies, CS treatment of subjects with asthma generally has 

### 16 not prevented O 3 - induced FEV 1 decrements (Section 6.2.1.1 ). Epidemiologic evidence is 

### 17 equivocal, with findings that use of inhaled CS attenuated ( Hernández

- Cadena et al., 

### 18
2009 ) , increased ( Lewis et al., 2005 ) , and did not affect ( Mortimer et al., 2000 ) , ambient 

### 19
O 3 - associated lung function decrements. In winter

- only studies, cons ideration of CS use 

### 20 largely did not influence associations between ambient O 3 and various lung function 

### 21
indices ( Liu et al., 2009a ; Rabinovitch et al., 2004 ) . Similarly equivocal evidence was 

### 22 found for modification of associations with respiratory symptoms (Section 6.2.4.1 ). The 

### 23 assessment of effect modification by CS use has been hampered by differences in the 

### 24 severity of asthma among CS users and the definition of CS use. Additionally, 

### 25
inves tigators did not assess adherence to reported CS regimen, and misclassification of 

### 26 CS use may bias findings. For example, Mortimer et al. (2000 ) classified children by no 

### 27 or any CS use at baseline but did not measure daily use during the study period. Lewis et 

### 28 al. (2005 ) defined CS use as use for at least 50% of study days and estimated larger 

### 29
O 3 - associated FEV 1 decrements among CS users ( Figure 6

- 6 and Table 6

- 8 ) than among 

### 30 CS nonusers (quantitative results not reported). In this st udy, most children with 

### 31 moderate to severe asthma (91%) were classified as CS users. However, CS users had a 

### 32 higher percent predicted FEV 1 . In contrast, Hernández

- Cadena et al. (2009 ) observed 

### 33 larger O 3 - related decrements in FEV 1 among the 60 CS nonusers than among the 25 CS 

### 34 users. A definition for CS use was not prov ided; however, children with persistent asthma 

### 35

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– Do Not Cite or Quote 6

- 51 June 2012 were included among the group of CS nonusers. Thus, across studies, both CS use and 

### 1 nonuse have been used to indicate more severe, uncontrolled asthma. 

### 2

Effect modification by antioxidant capacity

Ozone is a p owerful oxidant whose secondary oxidation products have been described to 

### 3 initiate the key modes of action that mediate decreases in lung function, including the 

### 4 activation of neural reflexes (Section 5.3.2 ). Additionally, O 3 exposure of humans and 

### 5 animals has induced changes in the levels of antioxidants in the ELF (Section 5.3.3 ). 

### 6 These observations provide biological plausibility for diminished antioxidant capacity to 

### 7
increase the risk of O 3 - associated respiratory effects and for augmented antioxidant 

### 8 capacity to decrease risk. Controlled huma n exposure studies have demonstrated the 

### 9 protective effects of α

- tocopherol (vitamin E) and ascorbate (vitamin C) supplementation 

### 10
on O 3 - induced lung function decrements (Section 6.2.1.1 ), and epidemiologic studies of 

### 11
children with asthma conducted in Mexico City produced similar findings. Particularly 

### 12 among children with moderate to severe asthma, increases in ambient O 3 con centration 

### 13
were associated with a smaller decrease in FEV 1 in the group supplemented with vitamin 

### 14 C and E as compared with the placebo group ( Romieu et al., 2002 ) ( Figure 6

- 6 and 

### 15
Table 6

- 8 ). Romieu et al. (2009 ) also demonstrated an interaction be tween dietary 

### 16
antioxidant intake and ambient O 3 concentrations by finding that the main effect of diet 

### 17 was modified by ambient O 3 concentrations. Diets high in antioxidant vitamins and/or 

### 18

omega

- 3 fatty acids protected against FEV 1 decrements at 8

- h max O 3 concentrations 

### 19
≥ 38 ppb. Results for the main effect of O 3 on FEV 1 or effect modification by diet were 

### 20 not presented. 

### 21

Antioxidant capacity also can be characterized by variants in genes encoding xenobiotic 

### 22 metabolizing enzymes with altered enzymatic activ ity. Ambient O 3 - associated FEF 25

- 75% 

### 23 decrements were larger among children with asthma with the GSTM1 null genotype, 

### 24 which is associated with lack of oxidant metabolizing activity ( Romieu et al., 2004b )

. 

### 25 The difference in association between GSTM1 null and positive subjects was minimal in 

### 26 children supplemented with antioxidant vitamins ( Figure 6

- 7 and Table 6

- 9 ). Although 

### 27 these findings are biologically plausible given the well

- cha racterized evidence for the 

### 28 secondary oxidation products of O 3 mediating effects, it is important to note that a larger 

### 29 body of controlled human exposure studies has not consistently found larger O 3 - induced 

### 30 lung function decrements in GSTM1 null subjects ( Section 6.2.1.1 ). Effect modification 

### 31 by GSTP1 variants is less clear. Romieu et al. (2006 ) observed larger O 3 - associated 

### 32
decreases in FEV 1 in children with asthma with the GSTP1 Ile/Ile or Ile/Val variant, 

### 33 which are associated with relatively higher oxidative metabolism activity ( Figure 6

- 6 and 

### 34
Table 6

- 8 ). An increase in ambient O 3 concentration was associa ted with an increase in 

### 35
FEV 1 among children with the GSTP1 Val/Val variant, which is associated with reduced 

### 36

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– Do Not Cite or Quote 6

- 52 June 2012 oxidative metabolism. Rather than reflecting effect modification by the GSTP1 variant, 

### 1 these results may reflect effect modification by asthma severity, as 77% of subjects with 

### 2 the GSTP1 Ile/Ile genotype had moderate to severe asthma. In support of this alternate 

### 3 hypothesis, another analysis of the same cohort indicated a larger O 3 - associated 

### 4
decrement in FEV 1 among children with moderate to seve re asthma than among all 

### 5 subjects with asthma ( Romieu et al., 2002 )

. 

### 6

Exposure Measurement Error

Across the studies of children with asthma, lung function decrements were associated 

### 7
with ambient O 3 concentrations assigned to subjects using various exposure assessment 

### 8
methods. As described in Section 4.3.3 , exposure measurement error due to use of 

### 9 ambient concentrations measured at central sites has varied, depending on the population 

### 10
and season examined. Because there are a limited number of stu dies of each method, it is 

### 11 difficult to conclude that a particular method of exposure assessment produced stronger 

### 12
results. 

### 13

Seasonal differences have been observed in the personal

- ambient O 3 relationship 

### 14 (Section 4.3.3 ); however, in children with asthma, O 3 - associated lung function 

### 15 decrements were found in studies conducted in summer months and over multiple 

### 16 seasons. Lung function was associated wit h O 3 measured on site of subjects’ daytime 

### 17
hours in summer months ( Hoppe et al., 2003 ; Thurston et al., 1997 ) , factors that have 

### 18 contributed to higher personal

- ambient O 3 ratios and correlations. Many year

- round 

### 19
stud ies in Mexico City ( Romieu et al., 2006 ; 2004b ; 2002 ; 1997 ; 1996 ) and a study in 

### 20 Detroit, MI ( Lewis et al., 2005 ) found associations with O 3 measured at sites within 5 km 

### 21 of children’s home or school. Children with asthma examined by Romieu et al. (2006 ); 

### 22 ( 2004b ; 2002 ) had a personal

- ambient ra tio and correlation for 48

- to 72

- h avg O 3 

### 23 concentrations were 0.17 and 0.35, respectively ( Ramírez

- Aguilar et al., 2008 ) . These 

### 24 findings indicate that the effects of personal O 3 exposure on lung function decrements 

### 25 may have been underestimated in the children in Mexico City. Associations were found 

### 26
with O 3 concentrations ave raged across multiple community monitoring sites ( O'Connor 

### 27 et al., 2008 ; Just et al., 2002 ; Mortimer et al., 2002 ; Jalaludin et al., 2000 ) and measured 

### 28 at a single site ( Gielen et al., 1997 ) , O 3 measured at multiple sites within a region have 

### 29 shown high temporal correlation ( Darrow et al., 2011a ; Gent et al., 2003 )

. 

### 30

Studies of children with asthma restricted to winter months provided little evidence of an 

### 31 association between various single

- and multi

- day lags of ambient O 3 concentration and 

### 32 lung function decrements with several studies reporting O 3 - associated increases in lung 

### 33
function ( Dales et al., 2009 ; Liu et al., 2009a ; Rabinovitch et al., 2004 ) . One explanation 

### 34 for these results may be lower indoor than outdoor O 3 concentrations, variable indoor to 

### 35

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– Do Not Cite or Quote 6

- 53 June 2012 outdoor ratios, and lower correlations between personal and ambient O 3 concentrations in 

### 1

non

- summer months (Section 4.3.2 and Section 4.3.3 ). As noted for other respiratory 

### 2 endpoints such as respiratory hospital admissions, ED visits, and mortality, associations 

### 3
with O 3 generally are lower in colder seasons. 

### 4

Adults with Respirato ry Disease

Relative to studies in children with asthma, studies of adults with asthma or COPD have 

### 5 been limited in number. Details from these studies regarding location, time period, and 

### 6
ambient O 3 concentrations are presented in Table 6

- 10 . Increases in ambient O 3 

### 7 concentration were not consistently associated with lung function decrements in adults 

### 8 with respiratory disease. Several different exposure assessment methods were used, 

### 9 including monitoring personal exposures ( Delfino et al., 1997 ) , monitoring on site of 

### 10
outdoor activit y ( Girardot et al., 2006 ; Korrick et al., 1998 ) , and using measurements 

### 11
from one ( Peacock et al., 2011 ; Wiwatanadate and Liwsrisakun, 2011 ; Thaller et al., 

### 12
2008 ; Ross et al., 2002 ) to several central monitors ( Khatri et al., 2009 ; Lagorio et al., 

### 13
2006 ; Park et al., 2005a ) . There was not a clear indication that differences in exposure 

### 14 assessment methodology contributed to inconsistencies in findings. 

### 15

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- 54 June 2012 Table 6

- 10 Mean and upper percentile concentrations of ozone in epidemiologic studies of lung function in adults with respiratory disease

. Study * Location Study Period O 3 Averaging Time Mean/Median Concentration (ppb) Upper Percentile Concentrations (ppb)

Delfino et al. (1997 ) Alpine, CA May

- July 1994 12

- h avg personal (8 a.m.

- 8 p.m.) 18 90th: 38 Max: 80

Girardot et al. (2006 ) Great Smoky Mountain NP, TN August

- October 2002 June

- August 2003 Hike

- time avg (2

- 9 h) 48.1 Max: 74.2

Korrick et al. (1998 ) Mt. Washington, NH Summer 1991, 1992 Hike

- time avg (2

- 12 h) 40 Max: 74

Peacock et al. (2011 ) London, England All

- year 1995

- 1997 8

- h max 15.5 Autumn/Winter Max: 32 Spring/Summer Max: 74

Wiwatanadate and Liwsrisakun (2011 ) Chiang Mai, Thailand August 2005

- June 2006 24

- h avg 17.5 90th: 26.82 Max: 34.65

Thaller et al. (2008 ) ; Brooks (2010 ) Galveston, TX Summer 2002

- 2004 1

- h max 35 (median) Max: 118

Ross et al. (2002 ) East Moline, IL April

- October 1994 8

- h avg 41.5 Max: 78.3

Khatri et al. (2009 ) Atlanta, GA May

- September 2003, 2005, 2006 8

- h max With asthma: 61(median) a
No asthma: 56 (median) a 75th (all subjects): 74 a

Lagorio et al. (2006 ) Rome, Italy May

- June, November

December 1999 24

- h avg Spring: 36.2 b
Winter: 8.0 b Overall max: 48.6 b

Park et al. (2005a ) Incheon, Kor ea March

- June 2002 24

- h avg Dust event days: 23.6 Control days: 25.1 NR

* Note: Studies presented in order of first appearance in the text of this section. NR = Not reported.

a Individual

- level estimates were calculated based on time spent in the vicinity of various O 3 monitors. b Concentrations converted from μg/m 3 to ppb using the conversion factor of 0.51 assuming standard temperature (25°C) and pressure (1 atm).

Comparisons of adults with asthma (8

- 18% of study population) and without asthma did 

### 1

not co nclusively demonstrate that adults with asthma had larger ambient O 3 - associated 

### 2 lung function decrements. Several studies examined on

- site or central

- site ambient O 3 

### 3 concentrations measured while subjects were outdoors, and ambient O 3 measured during 

### 4
time spent outdoors has been closer in magnitude and more correlated with personal 

### 5 exposures (Section 4.3.3 ). In a panel study of lifeguards (ages 16

- 27 years) in Galveston, 

### 6 TX, a larger O 3 - associated decrement in FEV 1 /FVC was found among the 16 lifeguards 

### 7 with asthma (

- 1.6% [95% CI:

- 2.8,

- 0.4] per 40 ppb increase in 1

- h max O 3 ) than among 

### 8 the 126 lifeguards without asthma (

- 0.40% [95% CI:

- 0.80, 0] per 40

- ppb increase in 

### 9

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– Do Not Cite or Quote 6

- 55 June 2012 1

- h max O 3 ) Brooks (2010 ) . In Korrick et al. (1998 )
, hikers with a history of asthma or 

### 1 wheeze had larger O 3 - associated lung function decrements (e.g.

- 4.4 % [95% CI:

- 7.5, 

### 2

- 1.2] in FEV 1 per 30

- ppb increase in 2

- 12 h avg O 3 ). In contrast, Girardot et al. (2006 ) 

### 3 generally did not f ind O 3 - associated lung function decrements in hikers with or without 

### 4 respiratory disease history. In a cross

- sectional study of 38 adults with asthma and 

### 5
13 adults without asthma, Khatri et al. (2009 ) used central site O 3 measurements but 

### 6 aimed to account for spatial variability by calculating an average of concentrat ions 

### 7 measured at sites closest to each subject’s location during each hour. Investigators 

### 8 reported a larger O 3 - associated decrease in percent predicted FEV 1 /FVC in the 38 

### 9 subjects with atopy (with or without asthma) (

- 12 points [95% CI:

- 21,

- 3] per 30

- ppb 

### 10
increase in 8

- h max O 3 ) than in subjects with asthma (

- 4.7 points [95% CI:

- 11, 2.3]). 

### 11 Among adults with asthma, O 3 was associated with an increase in FEV 1 . 

### 12

In panel studies that exclusively examined adults with asthma, increases in ambient O 3 

### 13
concentrati ons, across the multiple lags examined, generally were associated with 

### 14 increases in lung function ( Wiwatanadate and Liwsrisakun, 2011 ; Lagorio et al., 2006 ; 

### 15 Park et al., 2005a ) . These studies were conducted in Europe and Asia during periods of 

### 16
low ambient O 3 con centrations, including one conducted in Korea during a period of dust 

### 17

storms ( Park et al., 2005a ) 

### 18

Some studies included children and adults with asthma. Among subjects ages 9

- 46 years 

### 19 (41% adults) in Alpine, CA with low personal 12

- h avg O 3 exposures (55% samples 

### 20 below limit of detection) and a majori ty of sampling hours spent indoors (mean 71%), 

### 21 Delfino et al. (1997 ) reported that neither 12

- h avg personal exposure nor ambient O 3 

### 22
concentration was associated with a decrease in PEF. Ross et al. (2002 ) examined 

### 23 subjects ages 5

- 49 years (proportion of adults not reported) in East Moline, IL and found 

### 24
that a 20

- ppb increase in lag 0 of 24

- h avg O 3 was associated with a 2.6 L/min decrease 

### 25 (95% CI:

- 4.3,

- 0.90) in evening PEF. In this population with asthma, an increase in lag 0 

### 26
O 3 also was associated with an increase in symptom score. 

### 27

Controlled human exposure studies have found diminished, statistically non significa nt 

### 28
O 3 - induced lung function responses in older adults with COPD (Section 6.2.1.1 ). 

### 29 Similarly, epidemiologic studies do not provide strong evidence that short

- term increases 

### 30
in ambient O 3 exposure result in lung function decrements in adults with COPD. 

### 31 Inconsistent associations were reported for PEF, FEV 1 , and FVC in a study that followed 

### 32 94 adults with COPD (ages 40

- 83 years) in London, England daily over two years 

### 33 ( Peacock et al., 2011 ) . For example, a 30

- ppb increase in 8

- h max O 3 was associated with 

### 34 a 1.7 L/min decrease (95% CI:

- 3.1,

- 0.39) in PEF in an analysis of summer 1996 but not 

### 35 summer 1997 (

- 0.21 L/min [95% CI:

- 2.4, 2.0]). Further, in this study, an increase in 

### 36
ambient O 3 concentration was associated with lower odds of a large PEF decrement (OR 

### 37

### Draft

– Do Not Cite or Quote 6

- 56 June 2012 for a >20% drop from an individual’s median value : 0.89 [95% CI: 0.72, 1.10] per 

### 1
30

- ppb increase in lag 1 of 8

- h max O 3 ) and was not consistently associated with 

### 2 increases in respiratory symptoms ( Peacock et al., 2011 ) . Inconsistent associations also 

### 3 were reported in a small panel study of 11 adults with COPD (mean age 67 years) in 

### 4 Rome, Italy ( Lagorio et al., 2006 )

. 

### 5

Populations Not Restricted to Individuals with Asthma

Several studi es have examined associations between ambient O 3 concentrations and lung 

### 6 function in groups that included children with and without asthma; however, a limited 

### 7 number of studies have examined groups of children or adults restricted to healthy 

### 8
individuals. D etails from studies not restricted to individuals with asthma regarding 

### 9 location, time period, and ambient O 3 concentrations are presented in Table 6

- 11

. 

### 10

Table 6

- 11 Mean and upper percentile concentrations of ozone in epidemiologic studies of lung function in populations not restricted to individuals with as thma

. Study * Location Study Period O 3 Averaging Time Mean/Median Concentration (ppb) Upper Percentile Concentrations (ppb)
Avol et al. (1998b ) 6 southern CA
com munities Spring and summer 1994 24

- h avg personal NR NR

Hoppe et al. (2003 ) Munich, Germany Summers 1992 - 1995 30

- min max (1

- 4 p.m.) High O 3 days: 70.4 a Control O 3 days: 29.8 a Max (high O 3 days): 99 a Max (control O 3 days): 39 a
Chen et al. (1999 ) 3 Taiwan communities May

- January, 1995

- 1996 1

- h max (8 a.m.

- 6 p.m.) NR Max : 110.3 a

Gold et al . (1999 ) Mexico City, Mexico January

November 1991 24

- h avg 52.0 a Max : 103 a

Ward et al. (2002 ) Birmingham and Sandwell, England January

- March and May

- July 1997 24

- h avg Winter median: 13.0 Summer median: 22.0 Winter Max : 33 Summer Max : 41

Ulmer et al. (1997 ) Freudenstadt and Villingen, Germany March

- October 1994 30

- min avg Freudenstadt median: 50.6 Villingen median: 32.1 Freudenstadt 95th: 89.8

Villingen 95th: 70.1 Linn et al. (1996 ) Rubidoux, Upland, Torrence, CA September

- June 1992

- 1994 24

- h avg personal 24

- h avg ambient 5 23 Max: 16 Max: 53

Scarlett et al. (1996 ) Surrey, England June

- July 1994 8

- h max 50.7a Max: 128a

Neuberger et al. (2004 ) Vienna, Austria June

- October 1999, January

April 2000 NR NR NR

Alexeeff et al. (2008 ); ( 2007 ) Greater Boston, MA; NAS January 1995

- June 2005 48

- h avg 24.4b NR

### Draft

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- 57 June 2012 Study * Location Study Period O 3 Averaging Time Mean/Median Concentration (ppb) Upper Percentile Concentrations (ppb)
Steinvil et al. (2009 ) Tel Aviv, Israel September 2002

- November 2007 8

- h avg (10 a.m.

- 6 p.m.) 41.1 75th: 48.7 Max: 72.8 Naeher et al. (1999 ) Multiple
co mmunities, VA May

- September 1995

- 1996 8

- h max 53.7 Max : 87.6

Son et al. (2010 ) Ulsan, Korea All

- year, 2003

- 20 07 8

- h max 35.86 (avg of 13 monitors) Max : 59.53

* Note: Studies presented in order of first appearance in the text of this section. NAS = Normative Aging Study, NR = Not Reported.

a Measured at subjects’ schools where lung function was measured.

b Measured at central monitoring sites established by investigators. Concentrations were averaged across four monitors.

Children

Based on studies available at the time of the 2006 O 3 AQCD, evidence consistently links 

### 1
increases in ambient O 3 concentration with decrements in FEV 1 and PEF in children 

### 2 ( U.S. EPA, 2006b ) ( Figure 6

- 8 and Table 6

- 12 ). These associations were found with 

### 3 personal O 3 exposures ( Avol et al., 1998b ) , ambient O 3 measured at children’s schools 

### 4 where lung function was measured ( Hoppe et al., 2003 ; Chen et al., 1999 ; Gold et al., 

### 5
1999 ) , and ambient O 3 measured at sites within the community ( Ward et al., 2002 ; Ulmer 

### 6 et al., 1997 ; Linn et al., 1996 ) . Among children in Ca lifornia who spent a mean 2

- 3 hours 

### 7 outdoors per day and whose personal

- ambient O 3 correlation was 0.28 across multiple 

### 8

seasons, Avol et al. (1998b ) found slightly larger O 3 - associated decrements in FEV 1 and 

### 9
FVC for 24

- h avg personal exposures than for 1

- h max ambient measurements 

### 10 ( Figure 6

- 8 and Table 6

- 12 ). The effect estimates for personal exposures were similar in 

### 11 magnitude to those found in other studies f or ambient O 3 measured at schools ( Hoppe et 

### 12 al., 2003 ; Chen et al., 1999 ) . In another study of children in California, Linn et al. (1996 ) 

### 13 did not present results for personal O 3 exposures but found FEV 1 decrements in 

### 14
association with increases in ambient O 3 concentrations in children who spent 1

- 2 hours 

### 15 per day outdoors and whose personal

- ambient correlations were 0.61. Because of 

### 16
between

- s tudy heterogeneity in populations and ambient O 3 concentrations examined, it 

### 17 is difficult to assess how the method of exposure assessment may have influenced 

### 18 findings. 

### 19

### Draft

– Do Not Cite or Quote 6

- 58 June 2012 Note: The 95% CI was constructed using a standard error that was estimated from the p

- value. Results generally are presented in order of increasing mean ambient O 3 concentration. Effect estimates are from single

- pollutant models and are standardized to a 40

- , 30

- , and 20

- ppb increase for a 1

- hour (or 30

- min) max, 8

- h max, and 24

- h avg O 3 c oncentrations, respectively.


### Figure 6

- 8 Percent change in FEV 1 

### or FVC in association with ambient ozone concentrations in studies of children in the general population. Study
Linn et al. (1996)

Hoppe et al. (2003)

Scarlett et al. (1996)

Chen et al. (1999)

Avol et al. (1998) a Parameter
Intraday change FEV 1 Intraday change FVC

Afternoon FEV 1 Afternoon FVC

FEV 0.75 FVC

FEV 1 FVC

Intraday change FEV 1 Intraday change FVC O 3 Lag

0 0

0

1

1

0 Personal 0 Ambient 0 Personal 0 Ambient

- 10

- 8

- 6

- 4

- 2 0 2 Percent change in FEV 1 or FVC per unit increase in O 3 (95% CI)

### Draft

– Do Not Cite or Quote 6

- 59 June 2012 Table 6

- 12 Characteristics and quantitative data for studi es represented in Figure 6

- 8, of lung function in children.

Study * Location/ Population O 3 Averaging Time O 3 Lag Parameter Standardized Percent Change (95% CI) a
Linn et al. (1996 ) 3 southe rn CA communities 269 children, 4th and 5th grades 24

- h avg 0 Intraday cha nge FEV 1 Intraday change FVC - 0.58 (

- 1.0,

- 0.13)

- 0.21 (

- 0.62, 0.20)

Hoppe et al. (2003 ) Munich, Germany 44 children, ages 6

- 8 yr 30

- min max (1

- 4 p.m.) 0 Afternoon FEV 1 Afternoon FVC - 0.14 (

- 2.7, 2.5)

- 1.4 (

- 3.9,

- 1.2)

Scarlett et al. (1996 ) Surrey, England 154 children, ages 7

- 11 yr 8

- h max 1 FEV 0.75 FVC - 0.04 (

- 0.32, 0.23) 0.07 (

- 0.25, 0.39) Chen et al. (1999 ) 3 Taiwan communities 941 children,
mean (SD) age 9.8 (1.6) yr 1

- h max 1 FEV 1 FVC - 1.5 (

- 2.8,

- 0.12)

- 1.6 (

- 2.9,

- 0.33)

Avol et al. (1998b ) 3 southern CA communities 195 children, ages 10

- 12 yr 24

- h avg personal
1

- h max ambient
24

- h avg personal
1

- h max ambient 0 Intraday change FEV 1 Intraday change FEV 1 Intraday change FVC Intraday change FVC - 0.85 (

- 2.2, 0.53) b

- 0.49 (

- 1.5, 0.57) b

- 1.0 (

- 2.0, 0) b

- 0.50 (

- 1.3, 0.35) b

Studies of children not included in Figure 6

- 8 c
Ulmer et al. (1997 ) Freudenstadt and Villingen, Germany 135 children, ages 8

- 10 yr 30

- min max 1 FEV 1 (mL)

- 59 (

- 103, 14) b

Ward et al. (2002 ) Birmingham and Sandwell, England 162 children, age 9 yr 24

- h avg 0 2 Daily deviation from mean PEF (L/min) - 3.2 (

- 8.3, 2.0) d

- 6.7 (

- 12,

- 1.4) d
Gold et al. (1999 ) Mexico City, Mexico 40 children, ages 8

- 11 yr 24

- h avg 0 1

- 10 avg Intraday change PEF (% change) - 0.47 (

- 1.1, 0.11)

- 3.4 (

- 5.4,

- 1.5)

* I ncludes studies in Figure 6

- 8 plus others.

a Effect estimates are standardized to a 40

- , 30

- , and 20

- ppb increase for 1

- h (or 30

- min) max, 8

- h max, and 24

- h avg O 3 , respectively.

b The 95% CI was constructed using a standa rd error that was estimated from the p

- value.

c Results are not presented in Figure 6

- 8 because sufficient data were not provided to calculate percent change in FEV 1 or PEF was analyzed.

d Effect estimates are from analyses restricted to summer months.

In the limited number of studies that examined only healthy children, increases in 

### 1
ambient O 3 concentration were associated with decreases ( Hoppe et al., 2003 ) or no 

### 2 change in lung function ( Neuberger et al., 2004 ) . Several studies that included small 

### 3 proportions (4

- 10%) of children with history of respiratory disease or symptoms found 

### 4
associations between increases in ambient O 3 concentration and lung function decrements 

### 5 ( Chen et al., 1999 ; Ulmer et al., 1997 ; Scarlett et al., 1996 ) . Based on analysis of 

### 6
interaction terms for O 3 concentration and asthma/wheeze history, Avol et al. (1998b ) 

### 7

### Draft

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- 60 June 2012 and Ward et al. (2002 ) did not find differences in O 3 - associated lung function decrements 

### 1 between children with history of asthma or wheeze and healthy children. Combined, 

### 2
these lines of evidence indicate that the ambient O 3 - associated lung function decrements 

### 3 in children were not solely due to effects in children with asthma, and that increases in 

### 4
ambient O 3 exposure may decrease lung function in healthy children. 

### 5

Among the studies of children, the magnitudes of decrease in lung function per unit 

### 6
increase in ambient O 3 concentration 1 ranged from <1 to 4%, a range similar to that 

### 7 estimated in children with asthma. Comparable data were not adequately available to 

### 8 assess whether mean lung function differed between groups of children with asthma and 

### 9 healthy children. In contrast with children with asthma, O 3 - associated decreases in lung 

### 10 function were not consistently accompanied by O 3 - associated increases in respiratory 

### 11 symptoms in children in the general population. For example, Gold et al. (1999 ) found 

### 12
O 3 - associated decreases in PEF and increases in phlegm; however, the increase in phlegm 

### 13 was associated with lag 1 O 3 concentrations whereas the PEF decrement was found with 

### 14 single

- day lags 2 to 4 of O 3 . Also, O 3 was weakly associated with cough and shortness of 

### 15 breath among children in England ( Ward et al., 2002 ) and was associated with a decrease 

### 16 in respiratory sympto m score among children in California ( Linn et al., 1996 )

. 

### 17

Adults

Compared with children, in a more limited body of studies, O 3 was less consistently 

### 18 associated with lung function decrements in populations of adults not restricted to healthy 

### 19 subjects ( Table 6

- 13 ). In studies that included only healthy adults, increases in ambient 

### 20
O 3 concentration were associated with decreases ( Naeher et al., 1999 ) and increases in 

### 21 lung function ( Steinvil et al., 2009 ) . Contrasting results also were found in studies of 

### 22
older adults ( Alexeeff et al., 2008 ; Alexeeff et al., 2007 ; Hoppe et al., 2003 )

. 

### 23

1 Effect estimates were standardized to a 40

- , 30

- , and 20

- ppb increase for 1

- h max (or 30

- min max), 8

- h max, and 24

- h avg O 3 .

### Draft

– Do Not Cite or Quote 6

- 61 June 2012 Table 6

- 13 Associations between ambient ozone concentration and lung function in studies of adults.

Study a Location/ Population O 3 Averaging Time O 3 Lag Parameter O 3 Assessment Method/Subgroup Standardized Effect Estimate (95% CI) b

Son et al. (2010 ) Ulsan, Korea 2,102 children and adults, ages 7

- 97 yr 8

- h max 0

- 2 avg Change in percent predicted FEV 1 All monitor avg Nearest monitor IDW Kriging - 1.4 (

- 2.7,

- 0.08)

- 0.76 (

- 1.8, 0.25)

- 1.1 (

- 2.2, 0.05)

- 1.4 (

- 2.6,

- 0.11)

Steinvil et al. (2009 ) Tel Aviv, Israel 2,380 healthy adults,
mean age 43 yr, 75th percentile: 52 yr 8

- h avg (10 a.m

- 6 p.m.) 0 0

- 6 avg FEV 1 (mL) 60 (0, 120) 141 (33, 234)

Naeher et al. (1999 ) Multiple communities, VA 473 healthy women, ages 19

- 43 yr 24

- h avg 0 0

- 2 avg Evening PEF (L/min) - 1.7 (

- 3.4, 0.03)

- 3.0 (

- 4.4,

- 1.7)

Hoppe et al. (2003 ) Munich, Germany 61 older adults, ages 69

- 95 yr 30

- min max (1

- 4 p.m.) 0
1 % change in afternoon FEV 1 0.75 (

- 2.1, 3.7) 1.2 (

- 1.3, 3.6)

Alexeeff et al. (2008 ) Greater Boston, MA 1,015 older adults,
mean (SD) age: 68.8 (7.2) yr at baseline 24

- h avg 0

- 1 avg % change in FEV 1 GSTP1 Ile/Ile GSTP1 Ile/Val o r Val/Val - 1.0 (

- 2.2, 0.20)

- 2.3 (

- 3.5,

- 1.0)

Alexeeff et al. (2007 ) Greater Boston, MA 90 4 older adults,
mean (SD) age: 68.8 (7.3) yr at baseline 24

- h avg 0

- 1 avg % change in FEV 1 BMI <30 BMI ≥ 30 No AHR AHR BMI ≥ 30 and AHR - 1.5 (

- 2.5,

- 0.51)

- 3.5 (

- 5.1,

- 1.9)

- 1.7 (

- 2.7,

- 0.73)

- 4.0 (

- 6.2,

- 1.8)

- 5.3 (

- 8.2,

- 2.3)

a Results generally are presented in order of increasing mean ambient O 3 concentration. IDW = Inverse distance weighting, BMI = Body mass index, AHR = airway hyperresponsiveness. b Effect estimates are standardized to a 40

- ppb increase for 30

- min max O 3 , 30

- ppb increase for 8

- h ma x or 8

- h avg O 3 , and 20

- ppb increase for 24

- h avg O 3 .

Despite mixed results overall, lung function decrements in adults were associated with 

### 1
increases in ambient O 3 concentrations assigned to subjects using various methods with 

### 2 potentially varying degrees of measurement error. These methods included the average of 

### 3 multiple intra

- city monitors, nearest monitor, estimates from spatial interpolation ( Son et 

### 4 al., 2010 ) , average of monitors in multiple towns ( Alexeeff et al., 2008 ; 2007 ) , and one 

### 5 site for multiple towns ( Nae her et al., 1999 ) . In a large cross

- sectional study, conducted 

### 6 in 2,102 children and adults (mean age: 45 years) living near a petrochemical plant in 

### 7 Ulsan, Korea, Son et al. (2010 ) did not find a consistent difference in the magnitude of 

### 8 association with lung function among ambient O 3 concentrations averaged across 13 city 

### 9 monitors, concentrations from the nea rest monitor, inverse distance

- weighted 

### 10

### Draft

– Do Not Cite or Quote 6

- 62 June 2012 concentrations, and estimates from kriging across the various lags examined 

### 1 ( Table 6

- 13 ). Ozone concentrations were similar (<10% difference) and highly correlated 

### 2 (r = 0.84

- 96) among the methods. Although the health status of subjects was not reported, 

### 3 the study population mean percent predicted FEV 1 was 82.85%, indicating a large 

### 4 proportion of subjects with under lying airway obstruction. Results from this study were 

### 5 not adjusted for meteorological factors and thus, confounding cannot be ruled out. 

### 6 Importantly, the similarities among exposure assessment methods in Son et al. (2010 ) 

### 7 may apply mostly to populations living within the same region of a city. The majority of 

### 8 women examined by Naeher et al. (1999 ) l ived >60 miles from the single available 

### 9 central site monitor. However, in the nonurban (southwest Virginia) study area, O 3 

### 10 concentrations may be more spatially homogeneous (Section 4.6.2.1 ), and the 

### 11 concentrations measured at the single site may capture temporal variability in ambient 

### 12

exposures. 

### 13

The inconsistent findings for older adults parallel observations from controlled human 

### 14 exposure studies ( Section 6.2.1.1 ). In a study that followed adults ages 69

- 95 years over a 

### 15 summer in Germany, Hoppe et al. (2003 ) did not find decreases in lung function in 

### 16
association with ambient O 3 measured at subjects’ retirement home. However, recently, 

### 17 the Normative Aging Study found decrements i n FEV 1 and FVC in a group of older men 

### 18 (mean [SD] age = 68.9 [7.2] years) in association with ambient O 3 concentrations 

### 19 averaged from four town

- specific monitors ( Alexeeff et al., 2008 ) , which may less well 

### 20 represent spatial heterogeneity in ambient O 3 exposures. Among all subjects, who were 

### 21 examined once every three years for ten years, associations were found with several lags 

### 22
of 24

- h avg O 3 concentration, i.e., 1

- to 7

- day avg ( Alexeeff et al., 2008 ) . Additionally, 

### 23 larger effects were estimated in adults with airway hyperresponsiveness, highe r BMI (≥ 

### 24 30), and GSTP1 Ile/Val or Val/Val genetic variants (Val/Val variant produces enzyme 

### 25 with reduced oxidative metabolism activity) ( Alexeeff et al., 2008 ; Alexeeff et al., 2007 ) 

### 26 ( Table 6

- 13 ). Larger O 3 - related decrements in FEV 1 and FVC also were observed in 

### 27 subjects with long GT dinucleotide repeats in the promoter region of the gene for the 

### 28 antioxidant enzyme heme oxygenase

- 1 ( Alexeeff et al., 2008 ) , which has been associated 

### 29 with reduced inducibility ( Hiltermann et al., 1998 ) . In this cohort, O 3 also was associated 

### 30 with decreases in lung function in adults without airway hyperresponsiveness and those 

### 31 with BMI <30, indicating effects of O 3 on lung function in healthy older adults. However, 

### 32 the findings may be generalizable only to this study popul ation of older, predominately 

### 33
white men. 

### 34

Confounding in epidemiologic studies of lung function

The 1996 O 3 AQCD noted uncertainty regarding confounding by temperature and pollen 

### 35 ( U.S. EPA, 1996a ) ; however, collective evidence does not indicate that these factors fully 

### 36

### Draft

– Do Not Cite or Quote 6

- 63 June 2012 account for the associations observed between increases in ambient O 3 concentration and 

### 1 lung function decrements. Across the populations examined, most s tudies that found 

### 2
ambient O 3 - associated lung function decrements, whether conducted in multiple seasons 

### 3 or only in summer, included temperature in statistical analyses. Some summer camp 

### 4 studies conducted detailed analysis of temperature. In most of these s tudies, temperature 

### 5
and O 3 were measured at the camps. In two Northeast U.S. studies, an increase in 

### 6 temperature was associated with an increase in lung function ( Thurst on et al., 1997 ; 

### 7 Berry et al., 1991 ) . This positive association likely accounted for the nearly 2

- fold greater 

### 8
decrease in O 3 - associated PEF found by Thurston et al. (1997 ) with temperature in the 

### 9
model than with O 3 alone. In another Northeast U.S. camp study, Spektor et al. (1988a ) 

### 10
estimated similar effects for O 3 in a model with and without a temperature

- humidity 

### 11
index. In the re analysis of six camp studies, investigators did not include temperature in 

### 12 models because temperature within the normal ambient range had not been shown to 

### 13
affect O 3 - induced lung function responses in controlled human exposure studies ( Kinney 

### 14 et al., 1996 )

. 

### 15

Pollen was evaluated in far fewer studies. Camp studies that examined pollen found that 

### 16 pollen independently was not associated with lung function decrements ( Thurston et al., 

### 17
1997 ; Avol et al., 1990 ) . Many studies of children with asthma with follow

- up over 

### 18 multiple seasons found O 3 - associated decrements in lung function in models that adjusted 

### 19 for pollen counts ( Just et al., 2002 ; Ross et al., 2002 ; Jalaludin et al., 2000 ; Gielen et al., 

### 20
1997 ) . In these studies, large proportions of subjects had atopy (22

- 98%), with some 

### 21 studies examining large proportions of subjects specifically with pollen allergy and thus 

### 22 would be more responsive to pollen exposure ( Ross et al., 2002 ; Gielen et al., 1997 )

. 

### 23

A relatively larger number of studies provided information on potential confounding by 

### 24 copollutants such as PM 2.5 , PM 10 , NO 2 , or SO 2 . While studies were varied in how they 

### 25
evaluated confoun ding, most indicated that O 3 - associated lung function decrements were 

### 26 not solely due to copollutant confounding. Some studies of subjects exercising outdoors 

### 27 indicated that ambient concentrations of copollutants such as NO 2 , SO 2 , or acid aerosol 

### 28
were low a nd thus, not likely to confound associations observed for O 3 ( Hoppe et al., 

### 29
2003 ; Brunekreef et al., 1994 ; Hoek et al., 1993 ) . In other studies of children with 

### 30 increased outdoor exposures, O 3 was consistently associated with decreases in lung 

### 31 function, whereas other pollutants such as PM 2.5 , sulfate, and acid aerosol individually 

### 32
showed variable associations across studies ( Thurston et al., 1997 ; Castillejos et al., 1995 ; 

### 33 Berry et al., 1991 ; Avol et al., 1990 ; Spektor et al., 1988a ) . Most of these studies 

### 34 measured ambient pollutants on site of subjects’ outdoor activity and related lung 

### 35 function changes to the pollutant concentrations measured during outdoor activity. Thus, 

### 36 the degree of exposure measurement error likely is comp arable for O 3 and copollutants. 

### 37

### Draft

– Do Not Cite or Quote 6

- 64 June 2012 Studies that conducted copollutant modeling generally found O 3 - associated lung function 

### 1 decrements to be robust; most copollutant

- adjusted effect estimates fell within the 

### 2
95% CI of the single

- pollutant effect estimates ( Figure 6

- 9 and Table 6

- 14 ). These studies 

### 3
used central site measurements for both O 3 and copollutants. There may be residual 

### 4 confounding because of differential exposure measurement error for O 3 and copollutants 

### 5 due to differing spatial heterogeneity and indoor

- outdoor ratios; however, the limited 

### 6
avai lable evidence indicates that personal O 3 exposures are weakly correlated with 

### 7 personal PM 2.5 and NO 2 exposures (Section 4.3.4.1 ). Whereas a few stu dies used the same 

### 8 averaging time for copollutants ( Lewis et al., 2005 ; Jalaludin et al., 2000 ) , more 

### 9
examined 1

- h max or 8

- h max O 3 and 24

- h avg copollutant concentrations ( Son et al., 

### 10
2010 ; Chen et al., 1999 ; Romieu et al., 1997 ; Romieu et al., 1996 ) . In a Philadelphia

- area 

### 11 summer camp study, Neas et al. (1999 ) was among the few s tudies to find that the effect 

### 12
estimate for O 3 was attenuated to near zero in a copollutant model (24

- h avg sulfate in 

### 13 this study) ( Figure 6

- 9 and Table 6

- 14 ). 

### 14

Ambient O 3 concentrations showed a wide range of correlations with copollutant 

### 15 concentrations (r = - 0.31 to 0.74). In Sydney, Australia, Jalaludin et al. (2000 ) found low 

### 16
correlations of O 3 with PM 10 (r = 0.13) and NO 2 (r = - 0.31), all averaged over 24 hours. 

### 17
In two

- pollutant models, PM 10 and NO 2 remained associated with increases in PEF, and 

### 18
O 3 remained associated with decreases in PEF in children with asthma. In Detroit, MI, O 3 

### 19 was moderately correlated with PM 2.5 (Pearson r = 0.57) and PM 10 (Pearson r = 0.59), all 

### 20 averaged over 24 hours ( Lewis et al., 2005 ) . Adjustment for PM 10 or PM 2.5 resulted in a 

### 21 large change in the O 3 - associated FEV 1 decrement in children with asthma, but only in 

### 22 CS users and not in children with concurrent URI ( Figure 6

- 9 and Table 6

- 14 ). Studies 

### 23 conducted in Mexico City found small changes in O 3 - associated PEF decrements with 

### 24 copollutant adjustment although different avera ging times were used for copollutants 

### 25 ( Romieu et al., 1997 ; Romieu et al., 1996 ) ( Figure 6

- 9 and Table 6

- 14 ). In these studies, 

### 26
O 3 was moderately correlated with copollutants such as NO 2 and PM 10 (range of Pearson 

### 27

r = 0.38

- 0.58). Studies conducted in Asia also found that associations between O 3 and 

### 28 lung function were robust to adjustment for weakly

- to moderately

- correlated 

### 29 copollutants; effect estimates for copollutants generally were attenuated, indicating that 

### 30
O 3 may confound associations of copollutants ( Son et al., 2010 ; Chen et al., 1999 )

. 

### 31

In a sum mer camp study conducted in Connecticut, Thurston et al. (1997 ) found ambient 

### 32
concentrations of 1

- h max O 3 and 12

- h avg sulfate to be highly correlated (r = 0.74), 

### 33 making it difficult to separate their independent effects. With sulfate in the model, a 

### 34 larger decrease in PEF was estimated for O 3 ; however, the 95% CI was much wider 

### 35 ( Figure 6

- 9 and Table 6

- 14 ). Investigators found that the association for sulfate was due 

### 36
to one d ay when the ambient concentrations of both pollutants were at their peak. With 

### 37 the removal of this peak day, the sulfate effect was attenuated, whereas O 3 effects 

### 38

### Draft

– Do Not Cite or Quote 6

- 65 June 2012 remained robust ( Thurston et al., 1997 )

. Among children with asthma in Thailand, the 

### 1
O 3 - associated decrease in PEF was robust to adjustment of SO 2 ; however, different lags 

### 2
were examined for O 3 (lag 5) and SO 2 (lag 4) ( Wiwatanadate and Trakultivakorn, 2010 )

. 

### 3

Note: Results are presented first for FEV 1 then for PEF and then in order of increasing mean ambient O 3 concentration. a Information was not available to calculate 95% CI of the copollutant model. CS = corticosteroid, URI = Upper respiratory infection. Effect estimates are standardized to a 40

- , 30

- , and 20

- ppb increase for 1

- h max, 12

- h avg, and 24

- h avg O 3 , respectively. Black circles represent O 3 effect estimates from single pollutant models, and open circles represent O 3 effect estimates from copollutant models.


### Figure 6

- 9 Comparison of ozone

- associated chang es in lung function in single

- and co

- pollutant models. PEF Neas et al. (1999) a

Children attending camp

Thurston et al. (1997)

Children with asthma

Romieu et al. (1996)

Children with asthma

Romieu et al. (1997)

Children with asthma attending camp 12

- h avg, Lag 1

12

- h avg, Lag 1

1

- h max, Lag 0

1

- h max, Lag 0

1

- h max, Lag 0

1

- h max, Lag 0

1

- h max, Lag 0

1

- h max, Lag 0 None

24

- h avg, Lag 1 sulfate

None

12

- h avg, Lag 0 sulfate

None

24

- h avg, Lag 2 PM 2.5

None

24

- h avg, Lag 2 PM 10 ◄ ►

- 15

- 13

- 11

- 9

- 7

- 5

- 3

- 1 1 3 Percent change in PEF per unit increase in O 3 (95% CI) Study FEV 1 Lewis et al. (2005)

Children with asthma

Children with asthma

Chen et al. (1999)

Children using CS

with URI O 3 metrics

24

- h avg, Lag 2
24

- h avg, Lag 2
24

- h avg, Lag 2
24

- h avg, Lag 2
24

- h avg, Lag 2
24

- h avg, Lag 2

1

- h max, Lag 1
1

- h max, Lag 1 O 3 with copollutant

None
24

- h avg, Lag 2 PM 2.5 24

- h avg, Lag 2 PM 10 None
24

- h avg, Lag 2 PM 2.5 24

- h avg, Lag 2 PM 10

None
24

- h avg, Lag 1 NO 2 ◄ ►
►

- 15

- 13

- 11

- 9

- 7

- 5

- 3

- 1 1 3 Percent change in FEV 1 per unit increase in O 3 (95% CI)

### Draft

– Do Not Cite or Quote 6

- 66 June 2012 Table 6

- 14 Additional characteristics and quantitative data for studies represented in Figure 6

- 9

. Study * Location/Population Parameter O 3 - associated Percent Change in

Single

- Pollutant Model (95% CI) a O 3 - associated Percent Change in Copollutant Model (95% CI) a

PEF

Neas et al. (1999 ) Philadelphia, PA 156 Children at summer camp, ages 6

- 11 yr Morning PEF For 12

- h avg, Lag 1

- 0.94 (

- 2.0, 0.08) With 24

- h avg, Lag 1 sulfate

- 0.10 b

Thurston et al. (1997 ) CT River Valley 166 Children with asthma at summer camp, ages 7

- 13 yr Intraday change PEF For 1

- h max, Lag 0

- 2.8 (

- 4.9,

- 0.59) With 12

- h avg, Lag 0 sulfate

- 11.8 (

- 31.6, 8.1)

Romieu et al

. (1996 ) Mexico City, Mexico 71 children with asthma, ages 5

- 7 yr Evening PEF For 1

- h max, Lag 2

- 0.55 (

- 1.3, 0.19) With 24

- h avg, Lag 2 PM 2.5

- 0.24 (

- 1.2, 0.68)

Romieu et al. (1997 ) Mexico City, Mexico 65 children with asthma, ages 5

- 13 yr Evening PEF For 1

- h max, Lag 0

- 0.52 (

- 1.0,

- 0.01) With 24

- h avg, Lag 0 PM 10

- 0.79 (

- 1.4,

- 0.16)
FEV 1
Lewis et al. (2005 ) Detroit, MI Children with asthma using CS 393 person

- days Lowest daily FEV 1 For 24

- h avg, Lag 2 0.29 (

- 4.2, 5.0) With 24

- h avg, Lag 2 PM 2.5

- 0.18 (

- 11.0, 11.9) With 24

- h avg, Lag 2 PM 10

- 13.4 (

- 17.8,

- 8.8)

Children with asthma with URI 231 person

- days Overall mean (SD) age 9.1 (1.4 yr) For 24

- h avg, Lag 2

- 6.0 (

- 11.2,

- 0.41) With 24

- h avg, Lag 2 PM 2.5

- 5.5 (

- 10.3,

- 0.42) With 24

- h avg, Lag 2 PM 10

- 7.1 (

- 11.3,

- 2.8)

Chen et al. (1999 ) 3 Taiwan communities 941 children, mean (SD) age 9.8 (1.6) yr FEV 1 For 1

- h max, Lag 1

- 1.5 (

- 2.8,

- 0.12) With 24

- h avg, Lag 1 NO 2

- 2.0 (

- 3.5,

- 0.43)

### Draft

– Do Not Cite or Quote 6

- 67 June 2012 Study * Location/Population Parameter O 3 - associated Percent Change in

Single

- Pollutant Model (95% CI) a O 3 - associated Percent Change in Copollutant Model (95% CI) a
Results not included in Figure 6

- 9 c

Jalaludin et al. (2000 ) Sydney, Australia 125 children with asthma or wheeze, mean (SD) age 9.6 (1.0) yr Daily deviation from mean PEF For 24

- h avg, Lag 0

- 1.8 (

- 3.5,

- 0.19) With 24

- h avg, Lag 0 PM 10 ,

- 1.8 (

- 3.5,

- 0.19) With 24

- h avg, Lag 0 NO 2

- 1.8 (

- 3.4,

- 0.11)

Wiwatanadate and Trakultivakorn (2010 ) Chiang M ai, Thailand 31 children with asthma, ages 4

- 11 yr Evening PEF (L/min) For 24

- h avg, Lag 5

- 2.6 (

- 5.2, 0) With 24

- h avg, Lag 4 SO 2

- 3.2 (

- 6.2,

- 0.2)

Son et al. (2010 ) Ulsan, Korea 2,102 children and adults, ages 7

- 97 yr Change in percent predicted FEV 1 For 8

- h max, Lag 0

- 2 avg (kriging)

- 1.4 (

- 2.6,

- 0.11) With 24

- h avg, Lag 2 PM 10 (kriging)

- 1.8 (

- 3.4,

- 0.25)

*Includes studies in Figure 6

- 9 plus others. CS = Corticosteroid, URI = Upper respiratory infection.

a Effect estimates are standardized to a 40

- ppb inc rease for 1

- h max O 3 , 30

- ppb increase for 8

- h max or 12

- h avg O 3 , and 20

- ppb increase for 24

- h avg O 3 . b Information was not available to calculate 95% CI.

c Results are not presented in Figure 6

- 9 because sufficient data were not provided to calculate percent change in lung function.

Some studies did not provide quantitative results but reported that O 3 - associated lung 

### 1
function decrem ents remained statistically significa nt in models that included 

### 2 copollutants such as PM 10 , NO 2 , sulfate, nitrate, or ammonium ( Romieu et al., 1998b ; 

### 3 Brauer et al., 1996 ; Linn et al., 1996 ; Spektor et al., 1988b )

. 

### 4

Several studies estimated robust O 3 - associated lung function decrements in multipollutant 

### 5
models that most often included O 3 , NO 2 , and either PM 2.5 or PM 10 ( O'Connor et al., 

### 6
2008 ; Thaller et al., 2008 ; Chan and Wu, 2 005 ; Romieu et al., 2002 ; Korrick et al., 1998 ; 

### 7 Higgins et al., 1990 ) . However, the independent effects of O 3 are more difficult to assess 

### 8 in relation to incremental changes in more than one copollutant. 

### 9

Summary of Epidemiologic Studies of Lung Function

The cumulative body of epidemiologic evidence indicates that short

- term increases in 

### 10
ambient O 3 concentration are associated with decrements in lung function in children 

### 11 with asthma ( Figure 6

- 6 and Figure 6

- 7 and Table 6

- 8 and Table 6

- 9 ) and without 

### 12
asthma. In contrast with results from controlled human exposure studies, within

- study 

### 13 epidemiologic comparisons did not consistently indicate larger ambient O 3 - associated 

### 14 lung function decrements in groups with asthma (children or adults) than in groups 

### 15 without asthma. Notably, m ost epidemiologic studies were not designed to assess 

### 16

### Draft

– Do Not Cite or Quote 6

- 68 June 2012 between

- group differences. Based on comparisons between studies, differences were 

### 1
noted between children with and without asthma in so far as in studies of children with 

### 2 asthma, an increase in ambient O 3 concentration was associated concurrently with lung 

### 3 function decrements and increases in respiratory symptoms ( Just et al., 2002 ; Mortimer et 

### 4 al., 2002 ; Ross et al., 2002 ; Gielen et al., 1997 ; Romieu et al., 1997 ; Thurston et al., 

### 5
1997 ; Romieu et al., 19 96 ) . In studies of children in the general population, O 3 - associated 

### 6 decreases in lung function we re not accompanied by O 3 - associated increases in 

### 7 respiratory symptoms ( Ward et al., 2002 ; Gold et al., 1999 ; Linn et al., 1996 )

. 

### 8

Acro ss studies of children, there was no clear indication that a particular exposure 

### 9 assessment method using central site measurements produced stronger findings, despite 

### 10 potential differences in exposure measurement error. In children, lung function was 

### 11

assoc iated with ambient O 3 concentrations measured on site of children’s daytime hours 

### 12 ( Hoppe et al., 2003 ; Thurston et al., 1997 ) , at children’s schools ( Chen et al., 1999 ; Gold 

### 13 et al., 1999 ) , at the closest site ( Romieu et al., 2006 ; Lewis et al., 2005 ; Romieu et al., 

### 14
2004b ; 2002 ; 1997 ; 1996 ) , at multiple community sites then averaged ( O'Connor et al., 

### 15
2008 ; Just et al., 2002 ; Mortimer et al., 2002 ; Jalaludin et al., 2000 ) , and at a single site 

### 16 ( Ward et al., 2002 ; Gielen et al., 1997 ; Ulmer et al., 1997 ; Linn et al., 1996 ) . Among 

### 17 children in California, \ found slightly larger O 3 - associated lung func tion decrements for 

### 18
24

- h avg personal exposures than for 1

- h max ambient concentrations. 

### 19

As noted in the 1996 and 2006 O 3 AQCDs, evidence clearly demonstrates ambient 

### 20
O 3 - associated lung function decrements in children and adults engaged in outdoor 

### 21
recreati on, exercise, or work. Moreover, several results indicated associations with 10

- 

### 22
min to 12

- h avg O 3 concentrations <80 ppb. These studies are noteworthy for their 

### 23
measurement of ambient O 3 on site of and at the time of subjects’ outdoor activity, 

### 24
factors th at have contributed to higher O 3 personal exposure

- ambient concentration 

### 25 correlations and ratios (Section 4.3.3 ). These epidemiologic results are w ell supported by 

### 26 observations from controlled human exposure studies of lung function decrements 

### 27 induced by O 3 exposure during exercise (Section 6.2.1.1 ). Although investigation was 

### 28 relatively limited, increases in ambient O 3 concentration were not consistently associated 

### 29 with lung function decrements in adults with respiratory disease, healthy adults, or older 

### 30
adults. 

### 31

Across the diverse populations e xamined, most effect estimates ranged from a <1 to 2% 

### 32 decrease in lung function per unit increase in O 3 concentration 1 . Heterogeneity in 

### 33
O 3 - associated respiratory effects within populations was indicated by observations of 

### 34 larger decreases (3

- 8%) in childr en with asthma with CS use or concurrent URI ( Lewis et 

### 35 al., 2005 ) and older adults with airway hyperresponsiveness and/or BMI >30 ( Alexeeff et 

### 36

1 Effect estimates were standardized to a 40

- , 30

- , and 20

- ppb increase for 1

- h max, 8

- h max, and 24

- h avg O 3 .

### Draft

– Do Not Cite or Quote 6

- 69 June 2012 al., 2007 ) . Among children in Mexico City, high dietary antioxidant intake attenuated 

### 1
O 3 - associated lung function decrements ( Romieu et al., 2004b ; 2002 ) , similar to results 

### 2
from controlled h uman exposure studies. Each of these potential effect modifiers was 

### 3 examined in one to two populations; thus, firm conclusions about their influences are not 

### 4 warranted. Adding to the evidence for heterogeneity in response, Hoppe et al. (2003 ) and 

### 5 Mortimer et al. (2002 ) found that increases in ambient O 3 concentration were associated 

### 6 with increased incidence of >10% decline in lung function in children with asthma. 

### 7

Collectively, epidemiologic studies examined and found lung f unction decrements in 

### 8 association with single

- day O 3 concentrations lagged from 0 to 7 days and concentrations 

### 9 averaged over 2

- 10 days. More studies found associations with O 3 concentrations lagged 

### 10
0 or 1 day ( Son et al., 2010 ; Alexeeff et al., 2008 ; Lewis et al., 2005 ; Ross et al., 2002 ; 

### 11 Jalaludin et al., 2000 ; Chen et al., 1999 ; Romieu et al., 1997 ; Brauer et al., 1996 ; Romieu 

### 12 et al., 1996 ; Spektor et al., 1 988b ) than those lagged 5

- 7 days ( Wiwatanadate and 

### 13 Trakultivakorn, 2010 ; Hernández

- Cadena et al., 2009 ; Steinvil et al., 2009 ) . Associations 

### 14 with multiday average concentrations ( Son et al., 2010 ; Liu et al., 2009a ; Barraza



### 15 Villarreal et al., 2008 ; O'Connor et al., 2008 ; Alexeeff et al., 2007 ; Mortimer et al., 2002 ; 

### 16 Ward et al., 2002 ; Gold et al., 1999 ; Naeher et al., 1999 ; Neas et al., 1999 ) indicate that 

### 17 elevated exposures over several days may be important. Within studies, O 3 

### 18 concentrations for multiple lag periods were associated with lung function decrements, 

### 19 possibly indicating that multiple modes of action may be involved in the responses. 

### 20
Activation of bronchial C

- fibers (Section 5.3.2 ) may lead to decreases in lung function as 

### 21 an immediate response to O 3 exposure, and increased airway hyperresponsiveness to 

### 22 antigens resulting from sensitization of airways by O 3 (Se ction 5.3.5 ) may mediate lung 

### 23 function responses associated with lagged or multiday O 3 exposures ( Peden, 2011 )

. 

### 24

For single

- and multi

- day average O 3 concentrations, lung function decrements were 

### 25
associated with 1

- h max, 8

- h max, and 24

- h avg O 3 , with no strong difference in the 

### 26 consistency or magnitude of association among the aver aging times. For example, among 

### 27 studies that examined multiple averaging times, Spektor and Lippmann (1991 ) found a 

### 28 larger magnitude of associati on for 1

- h max O 3 than for 24

- h avg O 3 . However, other 

### 29 studies found larger magnitudes of association for longer averaging times [8

- h max in 

### 30 Chan and Wu (2005 ) and 12

- h avg in Thaller et al. (2008 ) ] than for 1

- h max O 3 . Other 

### 31
studies found no clear difference among O 3 averaging times ( Jalaludin et al., 2000 ; Chen 

### 32

et al., 1999 ; Scarlett et al., 1996 ; Berry et al., 1991 )

. 

### 33

Several studies found that associations with lung fu nction decrements persisted at lower 

### 34
ambient O 3 concentrations. For O 3 concentrations averaged up to 1 hour during outdoor 

### 35 recreation or exercise, associations were found in analyses restricted to O 3 concentrations 

### 36
<80 ppb ( Spektor et al., 1988a ; Spektor et al., 1988b ) , 60 ppb ( Brunekreef et al., 1994 ; 

### 37

### Draft

– Do Not Cite or Quote 6

- 70 June 2012 Spe ktor et al., 1988a ) , and 50 ppb ( Brunekreef et al., 1994 ) . Among outdoor workers, 

### 1 Brauer et al. (1996 ) found a robust association using daily 1

- h max O 3 concentrations 

### 2
<40 pp b. Ulmer et al. (1997 ) found a robust association in schoolchildren using 30

- min 

### 3
max O 3 concentrations <60 ppb. For 8

- hour avg O 3 concentrations, associations with lung 

### 4 function decrements in children with asthma were found to persist at concentrations 

### 5
<80 ppb in a U.S. multicity study (for lag 1

- 5 avg) ( Mortimer et al., 2002 ) and <51 ppb in 

### 6 a study conducted in the Netherlands (for lag 2) ( Gielen et al., 1997 )

. 

### 7

Evidence did not demonstrate strong confounding by meteorological factors and 

### 8 copollutant exposures. Most O 3 effect estimates for lung funct ion were robust to 

### 9 adjustment for temperature, humidity, and copollutants such as PM 2.5 , PM 10 , NO 2 , or SO 2 . 

### 10 Although examined in few epidemiologic studies, O 3 was associated with decreases in 

### 11 lung function with adjustment for pollen or acid aerosols. The c onsistency of association 

### 12 in the collective body of evidence with and without adjustment for ambient copollutant 

### 13 concentrations and meteorological factors combined with evidence from controlled 

### 14 human exposure studies for the direct effects of O 3 exposure p rovide strong support for 

### 15 the independent effects of short

- term ambient O 3 exposure on lung function decrements. 

### 16

6.2.1.3 Toxicology: Lung Function

The 2006 O 3 AQCD concluded that pulmonary function decrements occur in a number of 

### 17 species with acute exposures (≤ 1 week), ranging from 0.25 to 0.4 ppm O 3 ( U.S. EPA, 

### 18
2006b ) . Earl y work has demonstrated that during acute exposure of ~0.2 ppm O 3 in rats, 

### 19 the most commonly observed alterations are increased frequency of breathing and 

### 20 decreased tidal volume (i.e., rapid, shallow breathing). Decreased lung volumes are 

### 21
observed in rats with acute exposures to 0.5 ppm O 3 . At concentrations of ≥ 1 ppm, 

### 22 breathing mechanics (compliance and resistance) are also affected. Exposures of 6 h/day 

### 23
for 5 days create a pattern of attenuation of pulmonary function decrements in both rats 

### 24
and humans wi thout concurrent attenuation of lung injury and morphological changes, 

### 25 indicating that the attenuation did not result in protection against all the effects of O 3 

### 26 ( Tepper et al., 1989 ) . A number of studies examining the effects of O 3 on pulmonary 

### 27 function in rats, mice, and dogs are described in Table 6

- 13 on page 6

- 91 ( U.S. EPA, 

### 28
1996m ) of the 1996 O 3 AQCD
, and Table AX5

- 11 on page AX5

- 34 ( U.S. EPA, 2006f ) of 

### 29
the 2006 O 3 AQCD ( U.S. EPA, 2006b
, 1996a ) . Lung imaging studies using 

### 30 hyperpolarized 3 He provide evidence of ventilation abnormalities in rats following 

### 31 exposure to 0.5 ppm O 3 ( Crémillieux et al., 2008 ) . Rats were exposed to 0.5 ppm O 3 for 2 

### 32
or 6 days, either continuously (22 h/day) or alternatingly (12 h/day). Dynamic imaging of 

### 33 lung filling (2 mL/sec) revealed delayed and incomplete filling of lung segments an d 

### 34 lobes. Abnormalities were mainly found in the upper regions of the lungs and proposed to 

### 35

### Draft

– Do Not Cite or Quote 6

- 71 June 2012 be due to the spatial distribution of O 3 exposure within the lung. Although the small 

### 1 number of animals used in the study (n = 3 to 7/group) makes definitive conclus ions 

### 2 difficult, the authors suggest that the delayed filling of lung lobes or segments is likely a 

### 3 result of an increase in airway resistance brought about by narrowing of the peripheral 

### 4 small airways. 

### 5

6.2.2 Airway Hyperresponsiveness

Airway hyperresponsiveness refers to a condition in which the conducting airways 

### 6 undergo enhanced bronchoconstriction in response to a variety of stimuli. Airway 

### 7 responsiveness is typically quantified by measuring changes in pulmonary function 

### 8 (e.g., FEV 1 or specific airway resista nce [sRaw]) following the inhalation of an 

### 9 aerosolized specific (allergen) or nonspecific (e.g., methacholine) bronchoconstricting 

### 10 agent or another stimulus such as exercise or cold air. Asthmatics are generally more 

### 11 sensitive to bronchoconstricting agents than nonasthmatics, and the use of an airway 

### 12 challenge to inhaled bronchoconstricting agents is a diagnostic test in asthma. Standards 

### 13 for airway responsiveness testing have been developed for the clinical laboratory ( ATS, 

### 14
2000a ) , although variation in methodology for administering the bronchoconstricting 

### 15 agent may affect the results ( Cockcroft et al., 2005 ) . There is a wide range of airway 

### 16 responsiveness in nonasthmatic people, and responsiveness is influenced by a wide range 

### 17 of factors, including cigarette smoke, pollutant exposures, respiratory infections, 

### 18 occupational exposures, and respi ratory irritants. Airways hyperresponsiveness in 

### 19 response to O 3 exposure has not been examined widely in epidemiologic studies; such 

### 20 evidence is derived primarily from controlled human exposure and toxicological studies. 

### 21

6.2.2.1 Controlled Human Exposures

Beyond its direct effect on lung function, O 3 exposure causes an increase in airway 

### 22 responsiveness in human subjects. Increased airway responsiveness is an important 

### 23 consequence of exposure to ambient O 3 , because the airways are then predisposed to 

### 24 narrowing upon inhalation of a variety of ambient stimuli. 

### 25

Increases in airway responsiveness have been reported for exposures to 80 ppb O 3 and 

### 26
above. Horstman et al. (1990 ) evaluated airway responsiveness to methacholine in young 

### 27 healthy adults (22 M) exposed to 8 0, 100, and 120 ppb O 3 (6.6 hours, quasi continuous 

### 28 moderate exercise, 39 L/min). Dose

- dependent decreases of 33, 47, and 55% in the 

### 29 cumulative dose of methacholine required to produce a 100% increase in sRaw after 

### 30 exposure to O 3 at 80, 100, and 120 ppb, r espectively, were reported. Molfino et al. (1991 ) 

### 31

### Draft

– Do Not Cite or Quote 6

- 72 June 2012 reported increased allergen

- specific airway responsiveness in mild asthmatics exposed to 

### 1
120 ppb O 3 (1 hour resting ex posure). Due to safety concerns, however, the exposures in 

### 2
the Molfino et al. (1991 ) study were not randomized with FA conducted first and O 3 

### 3 exposure second. Attempts to reproduce the findings of Molfino et al. (1991 ) using a 

### 4 randomized exposure design have not found statistically significa nt changes in airway 

### 5 responsiveness at such low levels of O 3 exposure. At a considerably higher exposure to 

### 6
250 ppb O 3 (3 h, light

- to

- moderate intermittent exercise, 30 L/min), Jorres et al. (1996 ) 

### 7
found significa nt increases in specific and non

- specific airway responsiveness of mild 

### 8 asthmatics 3 hours following O 3 exposure. Kehrl et al. (1999 ) found increased reactivity 

### 9 to house dust mite antigen in mild atopic asthmatics 16

- 18 hours after exposure to 

### 10
160 ppb O 3 (7.6 hours, light quasi continuous exercise, 25 L/min). Holz et al. (2002 ) 

### 11 demonstrated that repeated daily exposure to lower concentrations of 125 ppb O 3 (3 hours 

### 12
for four consecutive days; intermittent exercise, 30 L/min) causes an incr eased response 

### 13 to allergen challenge at 20 hours postexposure in allergic airway disease. 

### 14

Ozone exposure of asthmatic subjects, who characteristically have increased airway 

### 15 responsiveness at baseline relative to healthy controls (by nearly two orders of 

### 16

m agnitude), can cause further increases in responsiveness ( Kreit et al., 1989 ) . Similar 

### 17 relative changes in airway responsiveness are seen in asthmatics and healthy control 

### 18 subject exposed to O 3 des pite their markedly different baseline airway responsiveness. 

### 19
Several studies ( Kehrl et al., 1999 ; Jorres et al., 1996 ; Molfino et al., 1991 ) have 

### 20 suggested an increase in specific (i.e., allergen

- induced) airway reactivity. An important 

### 21 aspect of increased airway responsiveness after O 3 exposure is that this may provide 

### 22 biological plausibility for associations observed between increases in ambient O 3 

### 23 concentrations and increased respiratory symptoms in children with asthma 

### 24 (Section 6.2.4.1 ) and increased hospital admissions and ED visits for asthma 

### 25 (Section 6.2.7 ). 

### 26

Changes in airway responsiveness after O 3 exposure appear to resolve more slowly than 

### 27 changes in FEV 1 or respiratory symptoms ( Folinsbee and Hazucha, 2000 ) . Studies 

### 28 suggest that O 3 - induced increases in airway responsiveness usually resolve 18 to 24 hours 

### 29 after exposure, but may persist in some indiv iduals for longer periods ( Folinsbee and 

### 30 Hazucha, 1989 ) . Furthermore, in studies of repeat ed exposure to O 3 , changes in airway 

### 31 responsiveness tend to be somewhat less susceptible to attenuation with consecutive 

### 32 exposures than changes in FEV 1 ( Gong et al., 1997a ; Folinsbee et al., 1994 ; Kulle et al., 

### 33
1982 ; Dimeo et al., 1981 ) . Increases in airway responsiveness do not appear to be 

### 34 strongly associated with decrements in lung function or increases in symptoms ( Aris et 

### 35 al., 1995 ) . Recently, Que et al. (2011 ) assessed methacholine responsiveness in healthy 

### 36 young adults (83M, 55 F) one day after exposure to 220 ppb O 3 and FA for 2.25 hours 

### 37 (alternating 15 min periods of rest and brisk treadmill walking). I ncreases in airways 

### 38

### Draft

– Do Not Cite or Quote 6

- 73 June 2012 responsiveness at 1 day post

- O 3 exposure were not correlated with FEV 1 responses 

### 1 immediately following the O 3 exposure nor with changes in epithelial permeability 

### 2
assessed 1 day post

- O 3 exposure. 

### 3

6.2.2.2 Toxicology: Airway Hyperresponsiveness

I n addition to human subjects, a number of species, including nonhuman primates, dogs, 

### 4 cats, rabbits, and rodents, have been used to examine the effect of O 3 exposure on airway 

### 5 hyperresponsiveness (see Table 6

- 14 on page 6

- 93 ( U.S. EPA, 1996n ) of the 1996 O 3 

### 6 AQCD and Table AX5

- 12 on page AX5

- 36 ( U.S. EPA, 2006g ) of the 2006 O 3 AQCD). 

### 7 With a few exceptions, commonly used animal models have been guinea pigs, rats, or 

### 8 mice acutely exposed to O 3 concentrations of 1 to 3 ppm to induce airway 

### 9 hyperresponsiveness. These animal models are helpful for determining underlying 

### 10 mechanisms of general airway hyperresponsiveness and are relevant for understanding 

### 11 airway responses in humans. Although 1

- 3 ppm may seem like a high exposure 

### 12 concentration, based on 18 O 3 (oxygen

- 18

- labeled O 3 ) in the BALF of humans and rats, an 

### 13 exposure of 0.4 ppm O 3 in exercising humans appears roughly equivalent to an exposure 

### 14
of 2 ppm in resting rats ( Hatch et al., 1994 )

. 

### 15

A limited number of studies have observed airway hyperresponsiveness in rodents and 

### 16 guinea pigs after exposure to less than 0.3 ppm O 3 . As previously reported in the 2006 O 3 

### 17 AQCD, one study demonstrated that a very low conce ntration of O 3 (0.05 ppm for 4 h) 

### 18 induced airway hyperresponsiveness in some of the nine strains of rats tested ( Depuydt et 

### 19 al., 1999 ) . This effect occurred at a concentration of O 3 that was much lower than has 

### 20 been reported to induce airway hyperresponsiveness in any other species. Similar to the 

### 21
effects of O 3 on other endpoints, these observations suggest a genetic component plays an 

### 22 important role in O 3 - induced airway hyperresponsiveness in this species and warrants 

### 23 verification in other species. More recently, Chhabra et al. (2010 ) demonstrated that 

### 24 exposure of ovalbumin (OVA)

- sensitized guinea pigs to 0.12 ppm for 2 h/day for 

### 25
4 weeks produced specific airway hyperresponsiveness to an inhaled OVA challenge. 

### 26 Interestingly, in this study, dietary supplemen tation of the guinea pigs with vitamins C 

### 27 and E ameliorated a portion of the airway hyperresponsiveness as well as indices of 

### 28 inflammation and oxidative stress. Larsen and colleagues conducted an O 3 C

- R study in 

### 29 mice sensitized by 10 daily inhalation treat ments with an OVA aerosol ( Larsen et al., 

### 30
2010 ) . Although airway responsiveness to m ethacholine was increased in non

- sensitized 

### 31 animals exposed to a single 3

- hour exposure to 0.5, but not 0.1 or 0.25 ppm O 3 , airway 

### 32 hyperresponsiveness was observed after exposure to 0.1 and 0.25 ppm O 3 in OVA



### 33
sensitized mice. 

### 34

### Draft

– Do Not Cite or Quote 6

- 74 June 2012 In order to evaluate the abil ity of O 3 to enhance specific and non

- specific airway 

### 1 responsiveness, it is important to take into account the phenomenon of attenuation in the 

### 2
effects of O 3 . Several studies have clearly demonstrated that some effects caused by acute 

### 3 exposure are absent a fter repeated or prolonged exposures to O 3 . The ability of the 

### 4 pulmonary system to adapt to repeated insults to O 3 is complex, however, and 

### 5 experimental findings for attenuation to O 3 - induced airway hyperresponsiveness are 

### 6 inconsistent. Airway hyperresponsiveness was observed in mice after a 3

- hour exposure 

### 7 but not in mice exposed continuously for 72 hours to 0.3 ppm ( John ston et al., 2005b )

. 

### 8 However, the Chhabra study demonstrated O 3 - induced airway hyperresponsiveness in 

### 9 guinea pigs exposed for 2 h/day for 10 days ( Chhabra et al., 2010 ) . Besides the obvious 

### 10 species disparity, thes e studies differ in that the mice were exposed continuously for 

### 11
72 hours, whereas the guinea pigs were exposed intermittently over 10 days, suggesting 

### 12 that attenuation might be lost with periods of rest in between O 3 exposures. 

### 13

Overall, numerous toxicolog ical studies have demonstrated that O 3 - induced airway 

### 14 hyperresponsiveness occurs in guinea pigs, rats, and mice after either acute or repeated 

### 15 exposure to relevant concentrations of O 3 . The mechanisms by which O 3 enhances the 

### 16 airway responsiveness to eithe r specific (e.g., OVA) or non

- specific (e.g., methacholine) 

### 17 bronchoprovocation are not clear, but appear to be associated with complex cellular and 

### 18 biochemical changes in the conducting airways. A number of potential mediators and 

### 19 cells may play a role in O 3 - induced airway hyperresponsiveness; mechanistic studies are 

### 20 discussed in greater detail in Section 5.3

. 

### 21

6.2.3 Pulmonary Inflammation, Injury and Oxida tive Stress

In addition to physiological pulmonary responses, respiratory symptoms, and airway 

### 22 hyperresponsiveness, O 3 exposure has been shown to result in increased epithelial 

### 23 permeability and respiratory tract inflammation. In general, inflammation can be 

### 24 considered as the host response to injury and the induction of inflammation as evidence 

### 25 that injury has occurred. Inflammation induced by exposure of humans to O 3 can have 

### 26 several potential outcomes: (1) inflammation induced by a single exposure (or sev eral 

### 27 exposures over the course of a summer) can resolve entirely; (2) continued acute 

### 28 inflammation can evolve into a chronic inflammatory state; (3) continued inflammation 

### 29 can alter the structure and function of other pulmonary tissue, leading to diseases such as 

### 30 fibrosis; (4) inflammation can alter the body’s host defense response to inhaled 

### 31 microorganisms, particularly in potentially at

- risk populations such as the very young and 

### 32 old; and (5) inflammation can alter the lung’s response to other agents such as allergens 

### 33 or toxins. Except for outcome (1), the possible chronic responses have only been directly 

### 34 observed in animals exposed to O 3 . It is also possible that the profile of response can be 

### 35

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– Do Not Cite or Quote 6

- 75 June 2012 altered in persons with preexisting pulmonary disease (e.g., asthma, COPD) or smokers. 

### 1 Oxidative stress has been shown to play a key role in initiating and sustaining O 3 - induced 

### 2 inflammation. Secondary oxidation products formed as a result of reactions between O 3 

### 3 and components of the ELF can increase the expression of cytokines, chemokines, and 

### 4 adhesion molecules and enhance airway epithelium permeability (Section 5.3.3 . and 

### 5
Section 5.3.4 ). 

### 6

6.2.3.1 Controlled Human Exposures

As reported in studies reviewed in the 1996 and 2006 O 3 AQCDs, acute O 3 exposure 

### 7 initiates an acute inflammatory response throughout the respiratory tract that has been 

### 8 observed to persist for at least 18

- 24 hours postexposure. A meta

- analysis of 21 studies 

### 9 ( Mudway and Kelly, 2004a ) for varied experimental protocols (80

- 600 ppb O 3 ; 

### 10
1

- 6.6 hours duration; light to heavy exercise; bronchoscopy at 0

- 24 hours post

- O 3 

### 11 exposure) showed that neutrophils (PMN) influx in healthy subjects was linearly 

### 12 associated (p <0.01) with total O 3 dose (i.e., the product of O 3 concentration, exposure 

### 13 duration, and V ̇ E ). As with FEV 1 responses to O 3 , within individual inflammatory 

### 14 responses to O 3 are generally reproducible and correlated between repeat e xposures ( Holz 

### 15 et al., 199 9 ) . Some individuals also appear to be intrinsically more susceptible to 

### 16 increased inflammatory responses to O 3 exposure ( Holz et al., 2005 )

. 

### 17

The presence of PMNs in the lung has long been accepted as a hallmark of inflammation 

### 18 and is an important indicator that O 3 causes inflammation in the lungs. Neutrophilic 

### 19 inflammation of tissues indicates activation of the innate immune system and requires a 

### 20 complex series of events that are normally followed by processes that clear the evidence 

### 21 of acute inflammation. Inflammatory effects have been assessed in vivo by lavage 

### 22 (proximal airway and bronchoalveolar), bronchial biopsy, and more recently, induced 

### 23 sputum. A single acute exposure (1

- 4 hours) of humans to moderate concentrations of O 3 

### 24 (200

- 600 ppb) while exercising at moderate to heavy intensities result s in a number of 

### 25 cellular and biochemical changes in the lung, including an inflammatory response 

### 26 characterized by increased numbers of PMNs, increased permeability of the epithelial 

### 27 lining of the respiratory tract, cell damage, and production of proinflam matory cytokines 

### 28 and prostaglandins ( U.S. EPA, 2006b ) . These c hanges also occur in humans exposed to 

### 29
80 and 100 ppb O 3 for 6

- 8 hours ( Alexis et al., 2010 ; Peden et al., 1997 ; Devlin et al., 

### 30
1991 )

. Significa nt (p = 0.002) increases in sputum PMN (16

- 18 hours postexposure) 

### 31 relative to FA responses have been recently repo rted for 60 ppb O 3 which is the lowest 

### 32 exposure concentration that has been investigated in young healthy adults ( Kim et al., 

### 33
2011 ) . Soluble mediators of inflammation such as the cytokines (e.g., IL

- 6, IL

- 8) and 

### 34
arachidonic a cid metabolites (e.g., prostaglandin [PG]E 2 , PGF 2α , thromboxane, and 

### 35

### Draft

– Do Not Cite or Quote 6

- 76 June 2012 leukotrienes [LTs] such as LTB 4 ) have been measured in the BALF of humans exposed 

### 1
to O 3 . In addition to their role in inflammation, many of these compounds have 

### 2 bronchoconstrictive proper ties and may be involved in increased airway responsiveness 

### 3 following O 3 exposure. The possible relationship between repetitive bouts of acute 

### 4 inflammation in humans caused by O 3 and the development of chronic respiratory disease 

### 5
is unknown. 

### 6

Asthma

Inflam matory responses to O 3 exposure have also been studied in asthmatic subjects. 

### 7 Asthmatics exposed to 200 ppb O 3 for 4

- 6 hours with exercise show significa ntly more 

### 8 neutrophils in BALF (18 hours postexposure) than similarly exposed healthy individuals 

### 9 ( Scannell et al., 1996 ; Basha et al., 1994 ) . In allergic asthmatics who tested positive for 

### 10 Dermatophagoides farinae antigen, there was an eosinophilic inflammation (2

- fold 

### 11 increase), as well as neutrophilic inflammation (3

- fold increase) 18 hours after exposure 

### 12
to 160 ppb O 3 for 7.6 hours with exercise ( Peden et al., 1997 ) . In a study of subjects with 

### 13 intermittent asthma exposed to 400 ppb O 3 for 2 hours, increases in eosinophil catio nic 

### 14 protein, neutrophil elastase and IL

- 8 were found to be significa ntly increased 16 hours 

### 15 postexposure and comparable in induced sputum and BALF ( Hiltermann et al., 1999 ) . At 

### 16
18 hours post

- O 3 exposure (200 ppb, 4 hours with exercise) and corrected for FA 

### 17

responses, Scannell et al. (1996 ) found significa ntly increased neutrophils in 18 

### 18 asthmatics (12%) compared to 20 healthy subjects (4.5%). This difference in 

### 19 inflammatory response was observed despite no group differences in spirometric 

### 20 responses to O 3 . Scannell et al. (1996 ) also reported that IL

- 8 tends to be higher in the 

### 21 BALF of asthmatics compared to nonasthmatics following O 3 exposure, suggesting a 

### 22 possible mediator for the significa ntly increased neutrophilic inflammation in those 

### 23 subjects. Bosson et al. (2003 ) found significa ntly greater epithelial expression of IL

- 5, 

### 24
IL

- 8, granulocyte

- macrophage colony

- stimulating factor and epithelial cell

- derived 

### 25 neutrophil

- activating peptide

- 78 in asthmatics com pared to healthy subjects following 

### 26 exposure to 200 ppb O 3 for 2 h. In contrast, Stenfors et al. (2002 ) did not detect a 

### 27
difference in the O 3 - induced incr eases in neutrophil numbers between 15 mild asthmatic 

### 28 and 15 healthy subjects by bronchial wash at the 6 hours postexposure time point. 

### 29 However, the asthmatics were on average 5 years older than the healthy subjects in this 

### 30 study, and it is not yet known h ow age affects inflammatory responses. It is also possible 

### 31 that the time course of neutrophil influx differs between healthy and asthmatic 

### 32 individuals. Differences between asthmatics and healthy subjects in O 3 - mediated 

### 33 activation of innate and adaptive imm une responses have been observed in two studies 

### 34 ( Hernandez et al., 2010 ; Bosson et al., 2003 ) , as discussed in Section 6.2.5.4 and 

### 35
Section 5.4.2.2

. 

### 36

### Draft

– Do Not Cite or Quote 6

- 77 June 2012 Vagaggini et al. (2002 ) investiga ted the effect of prior allergen challenge on responses in 

### 1 mild asthmatics exposed for 2 hours to 270 ppb O 3 or filtered air. At 6 hours 

### 2 postexposure, eosinophil numbers in induced sputum were found to be significa ntly 

### 3 greater after O 3 than after air expos ures. Studies such as this suggest that the time course 

### 4 of eosinophil and neutrophil influx following O 3 exposure can occur at levels detectable 

### 5 within the airway lumen by as early as 6 h. They also suggest that the previous or 

### 6 concurrent activation of pro inflammatory pathways within the airway epithelium may 

### 7 enhance the inflammatory effects of O 3 . For example, in an in vitro study of primary 

### 8 human nasal epithelial cells and BEAS

- 2B cell line, cytokine production induced by 

### 9
rhinovirus infection was enhanced synergistically by concurrent exposure to O 3 at 

### 10
200 ppb for 3 hours ( Spannhake et al., 2002 )

. 

### 11

A few studies have evaluate d the effects of corticosteroid usage on the response of 

### 12
asthmatics to O 3 . Vagaggini et al. (2007 ) evaluated whether corticosteroid usage would 

### 13 prevent O 3 - induced lung function decrements and inflammatory responses in a group of 

### 14 subjects with mild persistent asthma (n = 9; 25 ± 7 years). In this study, asthmatics were 

### 15 randomly exposed on four occasions to 270 ppb O 3 or FA for 2 hours with moderate 

### 16 exercise. Exposures were preceded by four days of treatment with prednisone or placebo. 

### 17 Pretreatment with corticosteroids prevented an inflamma tory response in induced sputum 

### 18 at 6 hours postexposure. FEV 1 responses were, however, not prevented by corticosteroid 

### 19 treatment and were roughly equivalent to those observed following placebo. Vagaggini et 

### 20 al. (2001 ) also found budesonide to decrease airway neutrophil influx in asthmatics 

### 21 following O 3 exposure. In contrast, inhalation of corticosteroid budesonide failed to 

### 22 prevent or atte nuate O 3 - induced responses in healthy subjects as assessed by 

### 23 measurements of lung function, bronchial reactivity and airway inflammation 

### 24 ( Nightingale et al., 2000 ) . High doses of inhaled fluticasone and oral prednisolone have 

### 25 each been reported to reduce inflammatory responses to O 3 in healthy individuals ( Holz 

### 26 et al., 2005 )

. 

### 27

Stenfors et al. (2010 ) exposed persistent asthmatics (n = 13; aged 33 years) receiving 

### 28 chronic inhaled corticosteroid therapy to 200 ppb O 3 for 2 hours with moderate exercise. 

### 29 At 18 hours postexpos ure, there was a significa nt O 3 - induced increase in 

### 30 bronchioalveolar lavage (BAL) neutrophils, but not eosinophils. Bronchial biopsy also 

### 31
showed a significa nt O 3 - induced increase in mast cells. This study suggests that the 

### 32 protective effect of acute cortic osteroid therapy against inflammatory responses to O 3 in 

### 33 asthmatics demonstrated by Vagaggini et al. (2007 ) may be lost with continued treatment 

### 34 regimes. 

### 35

### Draft

– Do Not Cite or Quote 6

- 78 June 2012 Associations between Inflammation and FEV 1 responses

Studies reviewed in the 2006 O 3 AQCD reported that inflammatory responses do not 

### 1 appear to be correlated with lung function responses in either asthmatic or healthy 

### 2 subjects. In healthy adults (14 M, 6 F) and asthmatic (12 M, 6 F) volunteers exposed to 

### 3
200 ppb O 3 (4 hours with moderate quasi continuous exercise, V ̇ E = 44 L/min), percent 

### 4 PMN and total protein in BAL fluids were significa ntly increased in the asthmatics 

### 5 relative to the healthy controls. Spirometric measures of lung function were significa ntly 

### 6 decreased following the O 3 exposure in both groups, but were not significa ntly di fferent 

### 7 between the asthmatic and healthy subjects. Effects of O 3 on PMN and total protein were 

### 8 not correlated with changes in FEV 1 or FVC ( Balmes et al., 1997 ; Balmes et al., 1996 )

. 

### 9 Devlin et al. (1991 ) exposed healthy adults (18 M) to 80 and 100 ppb O 3 ( 6.6

- hours with 

### 10 moderate quasi continuous exercise, 40 L/min). In BAL fluid collected 18 hours after 

### 11 exposure to 100 ppb O 3 , significa nt increases in PMNs, protein, PGE2, fibronectin, IL

- 6, 

### 12 lactate dehydrogenase, and α

- 1 antitrypsin compared to FA. Similar but smaller increases 

### 13 in all mediators were found after exposure to 80 ppb O 3 except for protein and 

### 14 fibronectin. Changes in BAL markers were not correlated with changes in FEV 1 . Holz et 

### 15 al. (1999 ) examined inflammatory responses in healthy (n = 21) and asthmatic ( n = 15) 

### 16 subjects exposed to 125 and 250 ppb O 3 (3 h, light intermittent exercise, 26 L/min). 

### 17 Significa ntly increased percent PMN in sputum due to O 3 exposure was observed in both 

### 18 asthmatics and healthy subjects following the 250 ppb exposure. At the lower 125 ppb 

### 19 exposure, only the asthmatic group experienced statistically significa nt increases in the 

### 20 percent PMN. Significa nt decrements in FEV 1 were only found following exposure to 

### 21
250 ppb; these changes in FEV 1 did not differ significa ntly between the asth matic and 

### 22 healthy groups and were not correlated with changes in PMN levels. Peden et al. (1997 ) 

### 23
also found no correlation between PMN and FEV 1 responses in 8 individuals with asthma 

### 24 exposed to 160 ppb O 3 for 7.6 hours with light

- to

- moderate exercise ( V ̇ E = 25 L/min). 

### 25 However, a marginally significa nt correlation (r = - 0.69, two

- tailed p = 0.08, n = 7) was 

### 26 observed between increases in the percent age of eosinophils and FEV 1 responses 

### 27 following O 3 exposure. 

### 28

In contrast to these earlier findings, Vagaggini et al. (2010 ) recently reported a significa nt 

### 29 (r = 0.61, p = 0.015) c orrelation between changes in FEV 1 and changes in sputum 

### 30 neutrophils in mild

- to

- moderate asthmatics (n = 23; 33 ± 11 years) exposed to 300 ppb 

### 31
O 3 for 2 hours with moderate exercise. Eight subjects were categorized as “responders” 

### 32
based on >10% FEV 1 decreme nts. There were no baseline differences between 

### 33 responders and nonresponders. However, at 6 hours post

- O 3 exposure, sputum 

### 34 neutrophils were significa ntly increased by 15% relative to FA in responders. The 

### 35 neutrophil increase in responders was also signific a ntly greater than the 0.2% increase in 

### 36 nonresponders. Interestingly, the nonresponders in the Vagaggini et al. (2010 ) study 

### 37

### Draft

– Do Not Cite or Quote 6

- 79 June 2012 experienced a significa nt O 3 - induced 11.3% increase in sputum eosinophils, while 

### 1 responders had an non significa nt 2.6% decrease. 

### 2

Time Course of the Inflammatory Response
The time course of the inflammatory response to O 3 in humans has not been fully 

### 3 characterized. Different markers exhibit peak responses at d ifferent times. Studies in 

### 4 which lavages were performed 1 hour after O 3 exposure (1 hours at 400 ppb or 4 hours at 

### 5
200 ppb) have demonstrated that the inflammatory responses are quickly initiated ( Torres 

### 6 et al., 1997 ; Devlin et al., 1996 ; Schelegle et al., 1991 ) . Inflammatory mediators and 

### 7 cytokines such as IL

- 8, IL

- 6, and PGE 2 are greater at 1 hours than at 18 hours post

- O 3 

### 8

exposure ( Torres et al., 1997 ; Devlin et al., 1996 ) . However, IL

- 8 still remained elevated 

### 9 at 18 hours post

- O 3 exposure (4 hours at 200 ppb O 3 versus FA) in healthy subjects 

### 10 ( Balmes et al., 1996 )

. Schelegle et al. (1991 ) found increased PMNs in the “proximal 

### 11 airway” lavage at 1, 6, and 24 hours after O 3 exposure (4 hours at 200 ppb O 3 ), with a 

### 12 peak response at 6 hours. However, at 18

- 24 hours after O 3 exposure, PMNs remain 

### 13 elevated relative to 1 hour postexposure ( Torres et al., 1997 ; Schelegle et al., 1991 )

. 

### 14

Genetic Polymorphisms
Alexis et al. (2010 ) recently reported that a 6.6

- hour exposure with moderate exercise to 

### 15
80 ppb O 3 caused increased sputum neutrophil levels at 18 hours postexposure in young 

### 16 healthy adults (n = 15; 24 ± 1 years). In a prior study, Alexis et al. (2009 ) found genotype 

### 17 effects on inflammatory responses to O 3 , but not lung function responses f ollowing a 

### 18
2

- hour exposure to 400 ppb O 3 . At 4 hours post

- O 3 exposure, both GSTM1 genotypes 

### 19
had significa nt increases in sputum neutrophils with a tendency for a greater increase in 

### 20
GSTM1

- sufficient than null individuals. At 24 hours postexposure, neutroph ils had 

### 21
returned to baseline levels in the GSTM1

- sufficient individuals. In the GSTM1

- null 

### 22 subjects, however, neutrophil levels increased further from 4 hours to 24 hours and were 

### 23 significa ntly greater than both baseline levels and 24 hours levels in GSTM1

- sufficient 

### 24
individuals. Alexis et al. (2009 ) found that GSTM1

- sufficient individuals (n = 19; 

### 25
24 ± 3 years) had a decrease in macrophage levels at 4

- 24 hours postexposure to 400 ppb 

### 26
O 3 for 2 hours with exercise. These studies also provide evidence for activation of innate 

### 27 immunity and antigen presentation, as discussed in Section 5.3.6 . Effects of the exposure 

### 28 apart from O 3 cannot be ruled out in the Alexis et al. (2010 ); ( 2009 ) studies, however, 

### 29 since no FA exposure was conducted. 

### 30

Vagaggini et al. (2010 ) examined FEV 1 and sputum neutrophils in mild

- to

- moderate 

### 31 asthmatics (n = 23; 33 ± 11 years) exposed to 300 ppb O 3 for 2 hours with moderate 

### 32 exercise. Six of the subjects were NQO1 wild type and GSTM1 n ull, but this genotype 

### 33
was not found to be associated with O 3 - induced changes in lung function or inflammatory 

### 34

### Draft

– Do Not Cite or Quote 6

- 80 June 2012 responses to O 3 . Kim et al. (2011 ) showed a significa nt (p = 0.002) increase in sputum 

### 1 neutrophil levels following a 6.6

- hour exposure to 60 ppb O 3 relative to FA in young 

### 2 healthy adults (13 F, 11 M; 25.0 ± 0.5 years). There was no significa nt effect of GSTM1 

### 3 genotype (half GSTM1

- null) on the inflammatory responses observed in these 

### 4
individuals. Previo usly, inflammatory responses had only been evaluated down to a level 

### 5
of 80 ppb O 3 . 

### 6

Repeated Exposures
Markers from BALF following both 2 hours ( Devlin et al., 1997 ) and 4 hours ( Jorres et 

### 7 al., 2000 ; Christian et al., 1998 ) repeated O 3 exposures (up to 5 days) indicate that there is 

### 8 ongoing cellular damage irrespective of the attenuation of some cellular inflammatory 

### 9 responses of the airways, pulmonary function, and symptom responses. Devlin et al

. 

### 10 (1997 ) found that several indicators of inflammation (e.g., PMN, IL

- 6, PGE 2 , fibronectin) 

### 11
were attenuated after 5 days of exposure (i.e., values were not different from FA). 

### 12 However, other markers (LDH, IL

- 8, total protein, epithelial cells) did not s how 

### 13 attenuation, suggesting that tissue damage probably continues to occur during repeated 

### 14 exposure. Some cellular responses did not return to baseline levels for more than 10

- 

### 15
20 days following O 3 exposure. Christian et al. (1998 ) showed decreased numbers of 

### 16 neutrophils and a decrease in IL

- 6 levels in healthy adults after 4 days of exposure versus 

### 17 the single exposure to 200 ppb O 3 for 4 h. Jorres et al. (2000 ) also found both functional 

### 18 and BALF cellular responses to O 3 were abolished at 24 hours postexposure following 

### 19 the fourth exposure day. However, levels of total protein, IL

- 6, IL

- 8, reduced gl utathione 

### 20
and ortho

- tyrosine were still increased significa ntly. In addition, visual scores 

### 21 (bronchoscopy) for bronchitis and erythema and the numbers of neutrophils in bronchial 

### 22 mucosal biopsies were increased. Results indicate that, d espite an attenuation of some 

### 23 markers of inflammation in BALF and pulmonary function decrements, inflammation 

### 24 within the airways persists following repeated exposure to O 3 . The continued presence of 

### 25 cellular injury markers indicates a persistent effect tha t may not necessarily be recognized 

### 26 due to the attenuation of spirometric and symptom responses. 

### 27

Epithelial Permeability

A number of studies show that O 3 exposures increase epithelial cell permeability through 

### 28 direct (technetium

- 99m labeled diethylene tri amine pentaacetic acid, 99m Tc

- DTPA, 

### 29 clearance) and indirect (e.g., increased BALF albumin, protein) techniques. Kehrl et al. 

### 30 (1987 ) sh owed increased 99m Tc

- DTPA clearance in healthy young adults (age 20

- 30 yrs) 

### 31 at 75 minutes postexposure to 400 ppb O 3 for 2 hours. Also in healthy young adults (age 

### 32
26±2 yrs), Foster and Stetkiewicz (1996 ) have shown that increased 99m Tc

- DTPA 

### 33 clearance persists for at least 18

- 20 hours po st

- O 3 exposure (130 minutes to average O 3 

### 34
concentration of 240 ppb), and the effect is greater at the lung apices than at the base. In a 

### 35

### Draft

– Do Not Cite or Quote 6

- 81 June 2012 older group of healthy adults (mean age = 35 yrs), Morrison et al. (2006 ) observed 

### 1

99m Tc

- DTPA clearance at 1 hours and 6 hours postexposure to O 3 (100 and 400 ppb; 1 

### 2 hour; moderate intermittent exercise, V ̇ E = 40 L/min) to be similar and not statistically 

### 3
different from 99m Tc

- DTPA clearance at 1 hours postexposure to FA (1 h; V ̇ E = 40 

### 4 L/min). 

### 5

Increased BALF protein, suggesting O 3 - induced changes in epithelial permeability, have 

### 6 also been reported at 1 hour an d 18 hours postexposure ( Devlin et al., 1997 ; Balmes et 

### 7 al., 1996 ) . Meta

- analysis of results from 21 publications ( Mudway and Kelly, 2004a ) for 

### 8 varied experimental protocols (80

- 600 ppb O 3 ; 1

- 6.6 hours duration; light to heavy 

### 9 exercise; bronchoscopy at 0

- 24 hours post

- O 3 exposure), showed that increased BALF 

### 10 protein is a ssociated with total inhaled O 3 dose (i.e., the product of O 3 concentration, 

### 11 exposure duration, and V ̇ E ). 

### 12

It has been postulated that changes in permeability associated with acute inflammation 

### 13 may provide increased access of inhaled antigens, particles, an d other inhaled substances 

### 14 deposited on lung surfaces to the smooth muscle, interstitial cells, and the blood. Hence, 

### 15 increases in epithelial permeability following O 3 exposure might lead to increases in 

### 16 airway responsiveness to specific and nonspecific ag ents. Que et al. (2011 ) investigated 

### 17 this hypothesis in healthy young adults (83M, 55 F) exposed to 220 ppb O 3 for 2.25 hours 

### 18 (alternating 15 min periods of rest and brisk treadmill walking). As has been observed by 

### 19
others for FEV 1 responses, within individual changes in permeab ility were correlated 

### 20 between sequential O 3 exposures. This indicates intrinsic differences in susceptibility to 

### 21 epithelial damage from O 3 exposure among individuals. Increases in epithelial 

### 22 permeability at 1 day post

- O 3 exposure were not correlated with F EV 1 responses 

### 23 immediately following O 3 exposure nor with changes in airway responsiveness to 

### 24
methacholine assessed 1 day post

- O 3 exposure. The authors concluded that changes in 

### 25
FEV 1 , permeability, and airway responsiveness following O 3 exposure were relati vely 

### 26 constant over time in young healthy adults; although, these responses appear to be 

### 27 mediated by differing physiologic pathways. 

### 28

6.2.3.2 Epidemiology

In the 2006 O 3 AQCD, epidemiologic evidence of associations between short

- term 

### 29
increases in ambient O 3 concent ration (30

- min or 1

- h max) and changes in pulmonary 

### 30 inflammation was limited to a few observations of increases in nasal lavage levels of 

### 31 inflammatory cell counts, eosinophilic cationic protein, and myeloperoxidases ( U.S. 

### 32 EPA, 2006b ) . In recent years, there has been a large increase in the number of studies 

### 33 assessing ambient O 3 - related changes in pulmonary inflammation and oxidative stress, 

### 34

### Draft

– Do Not Cite or Quote 6

- 82 June 2012 types of biological samples collected (i.e., lower airway), and types of indicators 

### 1 examined. Most studies collected samples every 1 to 3 weeks resulting in a total of 3 to 8 

### 2 sampl es per subject. These recent studies form a larger base to establish coherence with 

### 3 findings from controlled human exposure and animal studies that have measured the 

### 4 same or related biological markers. Additionally, these studies provide further biological 

### 5 plausibility for the associations observed between ambient O 3 concentrations and 

### 6 respiratory symptoms and asthma exacerbations. 

### 7

Despite the strengths of studies of inflammation, it is important to note that research in 

### 8 this field continues to develop, an d several uncertainties are recognized that may limit 

### 9
inferences of the effects of ambient O 3 exposure. Current areas of development include 

### 10 examination of the clinical relevance of the observed magnitudes of changes in biological 

### 11 markers of pulmonary infl ammation ( Murugan et al., 2009 ; Duramad et al., 2007 )
, 

### 12 characterization of the time course of changes between biomarker levels and other 

### 13 endpoints of respiratory morbidity, development of standardized methodologies for 

### 14 collection, improvement of the sensitivity and specificity of assay methods, and 

### 15 characterization of subject factors (e.g., asthma severity and recent medication use) that 

### 16
contribute to inter

- individual variability. These sources of uncertainty may contribute to 

### 17 differences in findings among studies. 

### 18

Although most of the biomarkers examined in epidemiologic studies were not specific to 

### 19 the lung, most studies collected exhaled breath, exha led breath condensate (EBC), nasal 

### 20 lavage fluid, or induced sputum with the aim of monitoring inflammatory responses in 

### 21 airways, as opposed to monitoring systemic responses in blood. The biomarker most 

### 22 frequently measured was exhaled nitric oxide (eNO), li kely related to its ease of 

### 23 collection in the field and automated measurement. Other biological markers were 

### 24 examined in EBC, induced sputum, and nasal lavage fluid, which are hypothesized to 

### 25 represent the fluid lining the lower or upper airways and contai n cytokines, cells, and/or 

### 26 markers of oxidative stress that mediate inflammatory responses ( Balbi et al., 2007 ; 

### 27 Howarth et al., 2005 ; Hunt, 2002 )

. Table 6

- 15 presents the locations, time periods, and 

### 28
ambient O 3 concentrations for studies examining associations with biological markers of 

### 29 pulmona ry inflammation and oxidative stress. Many studies found that short

- term 

### 30
increases in ambient O 3 concentration were associated with increases in pulmonary 

### 31 inflammation and oxidative stress, in particular, studies of children with asthma 

### 32
conducted in Mexico City ( Figure 6

- 10 and Table 6

- 16 and 

### 33

Table 6

- 17 ). 

### 34

### Draft

– Do Not Cite or Quote 6

- 83 June 2012 Table 6

- 15 Mean and upper percentile ozone concentrations in studies of biological markers of pulmonary inflammation and oxid ative stress

. Study * Location Study Period O 3 Averaging Time Mean /Median Concentration (ppb) Upper Percentile Concentrations (ppb)

Barraza

Villarreal et al. (2008 ) Mexico City, Mexico June 2003

- June 2005 8

- h moving avg 31.6 Max: 86.3

Berhane et al. (2011 ) 13 Southern California Communities September 2004

- June 2005 8

- h avg (10 a.m.

- 6 p.m.) NR NR

Liu et al. (2009a ) Windsor, ON, Canada October

December 2005 24

- h avg 13.0 95th: 26.5

Khatri et al. (2009 ) Atlanta, GA May

September 2003, 2005, 2006 8

- h max With asthma: 61 (median) a
No asthma: 56 (median) a 75th (all subjects): 74 a

Qian et al. (2009 ) Boston, MA; New York, NY; Denver, CO; Philadelphia, PA; San Francisco, CA; Madison, WI (SOCS) February 1997

- January 1999 8

- h max 33.6 75th: 44.4, Max: 91.5

Romieu et al. (2008 ) Mexico City, Mexico January

October 2004 8

- h max 31.1 75th: 38.3, Max: 60.7

Sienra

- Monge et al. (2004 ) Mexico City, Mexico All

- year 1999

- 2000 8

- h max 66.2 Max : 142.5

Ferdinands et al. (2008 ) Suburb of Atlanta, GA August 2004 1

- h max 61 (median) 75th: 67

Chimenti et al. (2009 ) Sicily, Italy November, February, July, year NR 8

- h avg (7 a.m.

– 3 p.m. ) November: 32.7 (pre

race), 35.1 (race) b February: 37.0 (pre

- race), 30.8 (race) b July: 51.2 (pre

- race), 46.1 (race) b NR

Nickmild er et al. (2007 ) Southern Belgium July

- August 2002 1

- h max NR Max (across 6 camps): 24.5

- 112.7 b
8

- h max NR Max (across 6 camps): 18.9

- 81.1 b

Delfino et al. (2010a ) Los Angeles, CA Warm and cold season 2005

- 2007 24

- h avg Warm season: 32.1 (median) c Cool season: 19.1 (median) c Max : 76.4 c
Max: 44.9 c

Adamkiewicz et al. (2004 ) Steubenville, OH September

December 2000 24

- h avg 1

- h avg d 15.3 19.8 75th: 20.2, Max: 32.2 75th: 27.5, Max: 61.6

* Note: Studies presented in order of first appearance in the text of this section. NR = Not Reported, SOCS = Salmeterol Off Corticosteroids Study.

a Individual

- level estimates were calculated based on time spent in the vicinity of various O 3 monitors.

b Concentrations converted from μg/m 3 to ppb using the conversion factor of 0.51 assuming standard temperature (25°C) and pressure (1 atm).

c Measurements outside subject’s residence (retirement home).

d Average O 3 concentration in the 1 hour preceding eNO collection.

### Draft

– Do Not Cite or Quote 6

- 84 June 2012 Note: Results are prese nted first for children with asthma then for adults with asthma and older adults. Effect estimates are from single

- pollutant models and are standardized to a 40

- ppb increase for 1

- h avg O 3 concentrations, a 30

- ppb increase for 8

- h max or 8

- h avg O 3 concent rations, and a 20

- ppb increase for 24

- h avg O 3 concentrations.


### Figure 6

- 10 Percent change in exhaled nitric oxide (eNO) in association with ambient ozone concentrations in populations with and without asthma. O 3 Lag

0
1

0

0
0

- 3 avg 1

- 23 cum avg

2

0, 24

- h avg
0, 1

- h avg

0

- 4 avg Study

Individuals with Liu et al. (2009)

Children with

Barraza

- Villarreal et al. (2008) Children

Qian et al. (2009)

Children and adults with asthma Berhane et al. (2011) Children

Khatri et al. (2009)

Older adults Adamkiewicz et al. (2004)

Delfino et al. (2010) Subgroup

Without asthma
With asthma

Without asthma
With asthma Without allergy With allergy

Cool season
Warm season asthma

asthma

►

►

►

►

► ◄

◄

◄

- 30

- 20

- 10 0 10 20 30 40 50 Percent change in eNO per unit increase in O 3 (95% CI)

### Draft

– Do Not Cite or Quote 6

- 85 June 2012 Table 6

- 16 Additional characteristics and quantitative data for studies represented in Figure 6

- 10.

Study * Location/Population O 3 Averaging Time O 3 Lag Subgroup Standardized % Change (95% CI) a

Studies in individuals with asthma
Liu et al. (2009a ) Windsor, ON, Canada 182 children with asthma, ages 9

- 14 yr 24

- h avg 0 1 - 25.1 (

- 42.9,

- 1.7)

- 17.5 (

- 32.1,

- 0.24)

Barraza

- Villarr eal et al. (2008 ) Mexico City, Mexico 208 children, ages 6

- 14 yr 8

- h max 0 Without asthma With asthma 13.5 (11.2, 15.8) 6.2 (6.0, 6.5)

Berhane et al. (2011 ) 13 Southern Cal ifornia communities 2,240 children, ages 6

- 10 yr 8

- h avg (10 a.m.

- 6 p.m.) 1

- 23 cummulative avg Without asthma With asthma Without allergy With allergy 30.1 (10.6, 53.2) 26.0 (

- 1.4, 60.9) 25.5 (5.3, 49.6) 32.1 (12.0, 55.9)

Qian et al. (2009 ) Boston, MA; New York, NY; Denver, CO; Philadelphia, PA; San F rancisco, CA; Madison, WI 119 children and adults with asthma, ages 12

- 65 yr 8

- h max 0 0

- 3 avg - 1.2 (

- 1.7,

- 0.64)

- 1.0 (

- 1.8,

- 0.26)

Khatri et al. (2009 ) Atlanta, GA 38 adults with asthma, ages 31

- 50 yr 8

- h max 2 36.6 (1.2, 71.9)

Studies in older adults

Adamkiewicz et al. (2004 ) Steubenville, Ohio 29 older adults, ages 53

- 90 yr 24

- h avg 1

- h avg b 0

- 5.7 (

- 25.9, 14.5)

- 19.7 (

- 41.3, 1.9)

Delfino et al. (2010a ) Los Angeles, CA 60 older adults, ages ≥ 65 yr 24

- h avg 0

- 4 avg Cool season Warm
season 35.2 (10.9, 59.5)

- 0.60 (

- 14.0, 12.8)

*Includes studies in Figure 6

- 10

.
a Effect estimates are standardized to a 40

- ppb, 30

- ppb, and 20

- ppb increase for 1

- h avg, 8

- h max or avg, and 24

- h avg O 3 , respectively.

b Average O 3 concentration in the 1 hour preceding eNO collection.

### Draft

– Do Not Cite or Quote 6

- 86 June 2012 Table 6

- 17 Associations between short

- term ambient ozone exposure and biological markers of pulmonary inflammation and oxidative stress.

Study Location/ Population O 3 Averaging Time O 3 Lag Biological Marker Subgroup Standardized Effect Estimate (95% CI) a

Liu et al. (2009a ) Windsor, ON, Canada 182 children with asthma, ages 9

- 14 yr 24

- h avg 0 EBC 8

- isoprostane (% change) EBC TBARS (% change) 16.2 (

- 14.9, 56.8) 11.5 (

- 27.0, 70.1)

Romieu et al. (2008 ) Mexico City, Mexico 107 children with asthma,
mean (SD) age 9.5 (2.1) yr 8

- h max 0 EBC Malondialdehyde b 1.9 (1.1, 3.5)

Barraza

Villarreal et al. (2008 ) Mexico City, Mexico 208 children, ages 6

- 14 yr 8

- h max 0 Nasal lavage IL

- 8 (pg/mL) Without asthma With asthma 1.6 (1.4, 1.8) 1.6 (1.4, 1.9)

EBC pH Without asthma With asthma - 0.10 (

- 0.27, 0.08) c

- 0.10 (

- 0.20, 0.01) c

Sienra

- Monge et al. (2004 ) Mexico City, Mexico 117 children with asthma,
mean age 9 yr 8

- h max 0

- 2 avg Nasal la vage IL

- 8 b Placebo Antioxidant 2.2 (1.1, 4.7) 1.0 (0.44, 2.3) Nasal lavage IL

- 6 b Placebo Antioxidant 2.7 (1.4, 5.1) 1.1 (0.53, 2.2) Nasal lavage Uric acid b Placebo Antioxidant 0.75 (0.44, 1.3) 1.3 (0.68, 2.4) Nasal lavage Glutathione b Placebo Antioxidant 0.79 (0.63, 0.98) 0.80 (0.66, 0.96)

Khatri et al. (2009 ) Atlanta, GA 38 adults with asthma, ages 31

- 50 yr 8

- h max 2 Blood eosinophils (% change) 2.4 (0.62, 4.2)

Ferdinands et al. (2008 ) Atlanta, GA 16 children exercising outdoors, ages 14

- 17 yr 1

- h max 0 EBC pH (normalized score) 0.80 (

- 0.20, 1.8) c

Results generally are presented in order of increasing mean ambient O 3 concentration. EBC = exhaled breath condensate, TBARS = thiobarbituric acid reactive substances, IL

- 8 = interleukin 8, IL

- 6 = interleukin 6, Antioxidant = group supplemented with vitamins C and E.

a Effect estimates are standardized to a 40

- , 3 0

- and 20

- ppb increase for 1

- h max, 8

- h max, and 24

- h avg O 3 , respectively.

b Effect estimates represent the ratio of the geometric means of biological marker per unit increase in O 3 concentration. A ratio <1 indicates a decrease in marker, and a ratio >1 indicates an increase in marker for an increase in O 3 .
c Model analyzed log

- transformed O 3 . Decreases and increases in pH indicate increases and decreases in pulmonary inflammation, respectively.

### Draft

– Do Not Cite or Quote 6

- 87 June 2012 Populations with Asthma

Exhaled Nitric Oxide

Neither NO nor eNO has been examined in controlled human exposure or toxicological 

### 1
studies of O 3 exposure. However, several lines of evidence support its analysis as an 

### 2 indicator of pulmonary inflammation. Inducible NO synthase can be activated by 

### 3

pro

- inflammatory cy tokines, and NO can be produced by cells such as neutrophils, 

### 4 eosinophils, and epithelial cells in the lung during an inflammatory response ( Barnes and 

### 5 Liew, 1995 ) . Further, eNO commonly is higher in individuals with asthma and increases 

### 6 during acute exacerbations ( Jones et al., 2001 ; Kharitonov and Barnes, 2000 )

. 

### 7

As indicated in Figure 6

- 10 and Table 6

- 16 , short

- term increases in ambient O 3 

### 8 concentration (8

- h max or avg) were associated with increases in eNO in children with 

### 9
asthma. These studies used different meth ods to assign exposures using central site O 3 

### 10 measurements: the site closest (within 5 km) to home or school ( Barraza

- Villarreal et al., 

### 11
2008 ) and a single site per community ( Berhane et al., 2011 ) . Because information on 

### 12 spatial homogeneity of ambient O 3 concentrations and time spent outdoors was not 

### 13 provided, it is not possible to assess whether these two methods differed in personal



### 14
ambient O 3 ratios and correlations. Liu et al. (2009a ) (described in Section 6.2.1.2 ) 

### 15 reported O 3 - associated decreases in eNO; however , this study was restricted to winter. 

### 16 Results for EBC markers of oxidative stress and lung function collectively provided weak 

### 17
evidence of O 3 - associated respiratory effects in this study. As described in Section 4.3.3
, 

### 18
in non

- summer months, indoor to outdoor O 3 ratios are lower as are personal

- ambient 

### 19 ratios, making it more difficult to detect associations with ambient O 3 concentrations. 

### 20

In contrast with controlled human exposure studies (Section 6.2.3.1 ), epidemiologic 

### 21 studies did not find larger O 3 - associated increases in pulmonary inflammati on in groups 

### 22 with asthma than in groups without asthma ( Figure 6

- 10 and Table 6

- 16 ). Among 

### 23 children in Southern California, Berhane et al. (2011 ) estimated similar associations for a 

### 24
1

- 23 day cumulative average of 8

- h avg (10 a.m.

- 6 p.m.) O 3 in children with and without 

### 25 asthma. Among children in Mexico City, Barraza

- Villarreal et al. (2008 ) found a larger 

### 26 association (for lag 0 of 8

- max O 3 ) in children without asthma, most of whom had atopy. 

### 27

Studies that included adults with asthma produced cont rasting results ( Khatri et al., 2009 ; 

### 28 Qian et al., 2009 ) . The multicity salmeterol (β

- 2 agonist) trial (Boston, MA; New York, 

### 29 NY; Denver, CO; Philadelphia, PA; San Francisco, CA; and Madison, WI) involved 

### 30 serial collection of eNO from 119 subjects with asthma, 87% of whom were 20

- 65 years 

### 31 of age ( Qian et al., 2009 ) . Ambient O 3 concentrations were averaged from all sites within 

### 32 20 miles of subjects’ zipcode centroids, which in a repeated measures study, may capture 

### 33 the temporal variation in O 3 reasonably well ( Darrow et al., 2011a ; Gent et al., 2003 )

. 

### 34

### Draft

– Do Not Cite or Quote 6

- 88 June 2012 Among all subjects, increases in 8

- h max O 3 at multiple lags (0 to 3 single

- day and 

### 1
0

- 4 avg) were associated with decreases in eNO. Results did not vary among the 

### 2
salmeterol

- , CS

- , and placebo

- treated groups, indicating tha t the counterintuitive findings 

### 3
for O 3 were not only due to the reduction of inflammation by medication. Qian et al. 

### 4 (2009 ) suggested that at higher concentrations, O 3 may transform NO in airways to 

### 5 reactive nitrogen species. However, this hypothesis was not supported by results from 

### 6 Khatri et al. (2009 ) , who in Atlanta, GA examined overall higher 8

- h max O 3 ambient 

### 7

conce ntrations than did Qian et al. (2009 ) and found that an increase in O 3 was associated 

### 8 with an increase in eNO in adults with asthma (36.6% [95% CI: 1.2, 71.9] per 30

- ppb 

### 9 increase in lag 2 of 8

- h max O 3 ). Although Khatri et al. (2009 ) was cross

- sectional and 

### 10 did not adjust for any meteorological factors, it may have better characterized O 3 

### 11 exposures because subjects were e xamined during warm months, and an 8

- h max O 3 

### 12 concentration was calculated for each subject using measurements at the site closest to 

### 13
his/her location each hour. 

### 14

Other biological markers of pulmonary inflammation and oxidative stress

Short

- term increases in ambient O 3 concentration were associated with changes in the 

### 15 levels of pro

- inflammatory cytokines and cells, indicators of oxidative stress, and 

### 16 antioxidants ( 

### 17

Table 6

- 17 ). Importantly, any particular biomarker was examined in only one to two 

### 18 studies, and the evidence in individuals with asthma is derived primarily from studies 

### 19 conducted in Mexico City ( Barraza

- Villarreal et al., 2008 ; Romieu et al., 2008 ; Sienra



### 20 Monge et al., 2004 ) . These studies measured ambient O 3 concentrations at sites within 5 

### 21 km of subjects’ schools or homes. In a Mexico City cohort of children with asthma, 

### 22
school ambient O 3 concentrations averaged over 48 to 72 hours had a ratio and 

### 23 correlation with personal exposures (48

- to 72

- h avg) of 0.17 and 0.35, respectively 

### 24 ( Ramírez

- Aguilar et al., 2008 ) . These observations suggest that the effects of personal O 3 

### 25 exposure on inflammation may have been underestimated in the Mexico City studies. 

### 26 Despite the limited evidence, the epidemiologic findings are well supported by controlled 

### 27 human exposure and toxicological studies that measured the same or related endpoints. 

### 28

Several of the modes of action of O 3 are mediated by reactive oxygen species (ROS) 

### 29 prod uced in the airways by O 3 (Section 5.3.3 ). These ROS are important mediators of 

### 30 inflammation as they regulate cytokine expression and inflammatory c ell activity in 

### 31 airways ( Heidenfelder et al., 2009 ) . Controlled human exposure and toxicological studies, 

### 32 frequently have found O 3 - induced increases in oxidative stress as shown by increases in 

### 33 prostaglandins (Section 5.3.3 and Section 6.2.3.1 ), which are produced by the 

### 34 peroxidation of cell membrane phospholipids ( Morrow et al., 1990 )

. Romieu et al. (2008 ) 

### 35

### Draft

– Do Not Cite or Quote 6

- 89 June 2012 analyzed EBC malondialdehyde (MDA), a thiobarbituric acid reactive substance, which 

### 1 like prostaglandins, is derived from lipid peroxidation ( Janero, 1990 ) . For a 30

- ppb 

### 2 increase in lag 0 of 8

- h max O 3 , the ratio of the geometric means of MDA was 1.3 

### 3 (95% CI: 1.0, 1.7). Similar results were reported for lags 1 and 0

- 1 avg O 3 . A limi tation 

### 4 of the study was that 25% of EBC samples had nondetectable levels of MDA, and the 

### 5 random assignment of concentrations between 0 and 4.1 nmol to these samples may have 

### 6
contributed random measurement error to the estimated O 3 effects. Because MDA 

### 7

repr esents less than 1% of lipid peroxides and is present at low concentrations, its 

### 8 biological relevance has been questioned. However, Romieu et al. (2008 ) pointed to their 

### 9 observations of statistically significa nt associations of EBC MDA levels with nasal 

### 10 lavage IL

- 8 levels to demonstrate its relationship with pulmonary inflammation. 

### 11

Uric acid and glutathione are ROS scavenge rs that are present in the airway ELF. While 

### 12 the roles of these markers in the inflammatory cascade of asthma are not well defined, 

### 13 they have been observed to be consumed in response to short

- term O 3 exposure as part of 

### 14 an antioxidant response in controlle d human exposure and animal studies (Section 5.3.3 ). 

### 15 Results from an epidemiologic study also indicate that a similar antioxidant response may 

### 16
be in duced by increases in ambient O 3 exposure. 2004 ) Sienra

- Monge et al. (2004 ) found 

### 17
O 3 - associated decreases in nasal lavage levels of uric acid and glutathione in children 

### 18 with asthma not supplemented with antioxidant vitam ins ( 

### 19

Table 6

- 17 ). The magnitudes of decrease were similar for O 3 concentrations lagged 2 or 

### 20
3 days and averaged over 3 days. 

### 21

Both controlled human ex posure and toxicological studies have found O 3 - induced 

### 22 increases in the cytokines IL

- 6 and IL

- 8 (Section 5.3.3 , Section 6.2.3.1 , and 

### 23
Section 6.2.3.3 ), which are involved in initiating an influx of neutrophils, a hallmark of 

### 24
O 3 - induced inflammation (Section 6.2.3.1 ). Epidemiologic studies conducted in Mexico 

### 25 City had similar findings. Sienra

- Monge et al. (2004 ) found that 8

- h max O 3 was 

### 26 associated with increases in nasal lavage levels of IL

- 6 and IL

- 8 (placebo group), with 

### 27 larger ef fects estimated for lag 0

- 2 avg than for lag 2 or 3 O 3 ( 

### 28

Table 6

- 17 ). In another cohort of children with asthma, a 30

- ppb increase in lag 0 of 

### 29
8

- h max O 3 was associated with a 1.61 pg/mL increase (95% CI: 1.4, 1.8) in nasal lavage 

### 30
levels of IL

- 8 ( Barraza

- Villarreal et al., 2008 ) . This study also reported a small 

### 31
O 3 - associated decrease in EBC pH ( 

### 32

Table 6

- 17 ). EBC pH, which is thought to reflect the proton

- buffering capacity of 

### 33 ammonium in airways, decreases upon asthma exacerbation, and is negatively correlated 

### 34 with airway levels of pro

- inflamma tory cytokines ( Carpagnano et al., 2005 ; Kostikas et 

### 35 al., 2002 ; Hunt et al., 2000 )

. 

### 36

### Draft

– Do Not Cite or Quote 6

- 90 June 2012 Albeit with limited investigation, controlled human exposure studies have found 

### 1
O 3 - indu ced increases in eosinophils in adults with asthma (Section 6.2.3.1 ). Eosinophils 

### 2
are believed to be the main effector cells that initiate and sust ain inflammation in asthma 

### 3 and allergy ( Schmekel et al., 2001 ) . Consistent with these findings, in a cross

- sectional 

### 4 study of adults with asthma in Atlanta, GA, a 30

- ppb increase in lag 2 of 8

- h max O 3 was 

### 5 associated with a 2.4% increase (95% CI: 0.62, 4.2) in blood eosinophils ( Khatri et al., 

### 6
2009 ) . Potential confounding by weather was not evaluated in models. 

### 7

The prominent influences demonstrated for ROS and antioxidants in mediating the 

### 8 respiratory eff ects of O 3 provide biological plausibility for effect modification by 

### 9 antioxidant capacity. Effect modification by antioxidant capacity has been described for 

### 10
O 3 - associated lung function in controlled human exposure and epidemiologic studies 

### 11 (Section 6.2.1.1 and Section 6.2.1.2 ). An epidemiologi c study conducted in Mexico City 

### 12 also found that vitamin C and E supplements, which potentially increase antioxidant 

### 13 capacity, attenuated O 3 - associated inflammation and oxidative stress. Among children 

### 14 with asthma supplemented daily with vitamin C and E, t he ratios of the geometric means 

### 15 of nasal lavage IL

- 6 and IL

- 8 per 30

- ppb increases in lag 0

- 2 avg of 8

- h max O 3 were 1.0, 

### 16 reflecting no change with increases in O 3 concentration ( 

### 17

Table 6

- 17 ) ( Sienra

- Monge et al., 2004 ) . The results did not clearly delineate interactions 

### 18 among O 3 concentrations, endogenous antioxidants, and dietary antioxidants ( 

### 19

Table 6

- 17 ). Ozone was associated with increases in uric acid in the antioxidant group 

### 20 but decreases in the placebo group across the O 3 lags examined. Associations with 

### 21 glutathione were similar in the two groups. In an other cohort, 8

- h max O 3 concentrations 

### 22
≥ 38 ppb enhanced the effects of diets high in antioxidant vitamins and/or omega

- 3 fatty 

### 23 acids on protecting against O 3 - related increases in nasal lavage IL

- 8 ( Romieu et al., 

### 24
2009 ) . Information on the main effects of O 3 or effect modification by diet was not 

### 25 presented. 

### 26

The levels of several biological markers such as eNO, EBC pH, and MDA consistently 

### 27 differ between groups with and without asthma and change during an asthma 

### 28
exacerbation ( Corradi et al., 2003 ; Hunt et al., 2000 ) ; however, the magnitudes of change 

### 29
associated with these overt effects are not well defined. Ozone

- associated increases in 

### 30
interleukins and indicators of oxidative stress were small: 1

- 2% increase for each 30

- ppb 

### 31
increase in 8

- h max O 3 concentration ( 

### 32

Table 6

- 17 ). Ozone

- associated increases in eNO were larger: 6

- 36% increase per 30

- ppb 

### 33
increase in 8

- h max ambient O 3 concentration ( Berhane et al., 2011 ; Delfino et al., 2010a ; 

### 34 Khatri et al., 2009 ; Barraza

- Villarreal et al., 2008 ) . Some studies in populations with 

### 35
asthma found O 3 - associated increases in pulmonary inflammation concurrently (at the 

### 36

### Draft

– Do Not Cite or Quote 6

- 91 June 2012 same lag) with O 3 - associated in respiratory symptoms. For example, among adults with 

### 1 asthma in Atlanta, an increase in ambient O 3 concentration was associated with increases 

### 2 in eNO, blood eosinophils, and a decrease in quality of life score, which incorporates 

### 3 indices for symptoms and activity limitations ( Khatri et al., 2009 ) . Also, among children 

### 4 with asthma in Mexico City, O 3 was associated with increases in eNO and nasal lavage 

### 5
IL

- 8 and concurrently asse ssed cough but not wheeze ( Ba rraza

- Villarreal et al., 2008 )

. 

### 6

Children without Asthma

In the limited investigation, short

- term increases in ambient O 3 concentration (8

- h max or 

### 7 avg) were associated with increases in pulmonary inflammation in children without 

### 8
asthma ( Berhane et al., 2011 ; Barraza

- Villarreal et al., 2008 ) ( Figure 6

- 10 and Table 6

- 16 

### 9
and 

### 10

Table 6

- 17 ). The study of children in Mexico City found a larger O 3 - associated increase 

### 11 in eNO in the children without asthma than with asthma (13.5% versus 6.2% increase per 

### 12
30

- ppb increase in lag 0 of 8

- h max O 3 ) ( Barraza

- Villarreal et al., 20 08 ) . Ozone was 

### 13 associated with similar magnitudes of change in IL

- 8 and EBC pH in children with and 

### 14 without asthma. A distinguishing feature of this study was that 72% of children without 

### 15 asthma had allergies. A study conducted in 13 Southern California communities also 

### 16
found that increases in ambient O 3 concentration (8

- h avg, 10 a.m.

- 6 p.m.) were 

### 17 associated with increases in eNO in children with respiratory allergy ( Berhane et al., 

### 18
2011 ) . Coherence for these epidemiologic findings is provided by observations of 

### 19
O 3 - induced allergic inflammation in animal models of allergy (Section 6.2.3.3 and 

### 20
Section 6.2.6 ). 

### 21

Berhane et al. (2011 ) found O 3 - associated increases in eNO in children without asthma 

### 22 and children without respiratory allergy, providing evidence for effects on pulmonary 

### 23 inflammation in healthy children. This study provided detailed information on differences 

### 24 in association among various lags o f 8

- h avg (10 a.m.

- 6 p.m.) O 3 . Ozone concentrations 

### 25 averaged over the several hours preceding eNO collection were not significa ntly 

### 26 associated with eNO. Consistent with other studies examining pulmonary inflammation 

### 27 and oxidative stress, Berhane et al. (2011 ) found that relatively short lags of O 3 , i.e., 1 to 

### 28
5 days, were associated with increases in eNO. However, among several types of lag



### 29 based models, including unconstrained lag models, polynomial distributed lag models, 

### 30 spline

- based distributed lag models, and cumulative lag models, a 23

- day cumulative lag 

### 31
of O 3 best fit the data. Among the studies evaluated in this ISA, Berhane et al. (2011 ) was 

### 32 unique in evaluating and finding larger respiratory effects for multi

- week (e.g., 13

- 

### 33
30 days) average O 3 concentrations. The mechanism for the effects of O 3 peaking with a 

### 34

### Draft

– Do Not Cite or Quote 6

- 92 June 2012 23

- day cumulative lag of exposure has not been delineated. Further, with examination of 

### 1 such long lag periods, there is greater potential for residual confounding by weather. 

### 2

Populations with Increased Outdoor Exposures

With limited investigation, increases in ambient O 3 concentration were not consistently 

### 3 associated with pulmonary inflammation in populations engaged in outdoor activity or 

### 4 exercise. Common limitations of these studies were the small numbers of subjects and 

### 5 lack of consideration for potential confounding f actors. A study in 16 adolescent long



### 6 distance runners near Atlanta, GA was noted for the daily collection of EBC and the 

### 7 likely greater extent to which ambient O 3 concentrations represented ambient exposures 

### 8 because of the analysis of O 3 concentrations me asured during outdoor running at a site 

### 9
less than 1 mile from the exercise track ( Ferd inands et al., 2008 ) . Increases in 1

- h max O 3 

### 10 (lags 0 to 2) were associated with increases in EBC pH, indicating O 3 - associated 

### 11 decreases in pulmonary inflammation. Among 9 adult male runners in Sicily, Italy 

### 12
examined 3 days before and 20 hours after 3 r aces in fall, winter, and summer, weekly 

### 13 average O 3 concentrations (8

- h avg, 7 a.m.

- 3 p.m.) were positively correlated with 

### 14 apoptosis of neutrophils (Spearman’s r = 0.70, p <0.005) and bronchial epithelial cell 

### 15 differential counts (Spearman’s r = 0.47, p < 0.05) but not with neutrophil or macrophage 

### 16 cell counts or levels of the pro

- inflammatory cytokines TNF

- α and IL

- 8 ( Chimenti et al., 

### 17
2009 ) . Associations with O 3 concentrations measured during the races (mean 35 to 89 

### 18 minutes) were not examined. This study provides evidence for new endpoints; however, 

### 19 the implications of findings are limited due to the lack of a rigorous statistical analysis. 

### 20

In a cross

- sectional study of children at camps in south Belgium, although lung function 

### 21
was not associated with O 3 measured at camps during outdoor activity, an association 

### 22
was found for eNO ( Nickmilder et al., 2007 ) . Children at camps with lag 0 1

- h max O 3 

### 23
concentrations >85.2 ppb had greater increases in intraday eNO compared with children 

### 24 at camps with O 3 concentration s <51 ppb. A benchmark dose analysis indicated that the 

### 25
threshold for an O 3 - associated increase of 4.3 ppb eNO (their definition of increased 

### 26 pulmonary inflammation) was 68.6 ppb for 1

- h max O 3 and 56.3 ppb for 8

- h max O 3 . 

### 27 While these results provide addit ional evidence for O 3 - associated increases in pulmonary 

### 28 inflammation in healthy children, they should be interpreted with caution since they were 

### 29 unadjusted for any potential confounding factors and based on camp

- level comparisons. 

### 30

Older Adults

The panel studies examining O 3 - associated changes in eNO in older adults produced 

### 31 contrasting findings ( Figure 6

- 10 and Table 6

- 16 ). The studies differed with respect to 

### 32 geographic location, inclusion of healthy subjects, exposure assessment method, and lags 

### 33

### Draft

– Do Not Cite or Quote 6

- 93 June 2012 of O 3 examined. Delfino et al. (2010a ) followed 60 older adults with coronary artery 

### 1
disease in the Los Angeles, CA area for 6 weeks each during a warm and cool season; the 

### 2 specific months were not specified. Ambient O 3 was measured at s ubjects’ retirement 

### 3 homes, possibly reducing some exposure measurement error due to spatial variability. 

### 4 Multiday averages of O 3 (3

- to 9

- day) were associated with increases in eNO, with effect 

### 5 estimates increasing with increasing number of averaging days. In contrast with most 

### 6 other studies, an association was found in the cool season but not warm season (increase 

### 7 in eNO per 20

- ppb increase in lag 0

- 4 avg of 24

- h avg O 3 : 4.1 ppb [95% CI: 1.3, 6.9] in 

### 8 cool season,

- 0.01 ppb [95% CI:

- 2.3, 2.1] in warm seaso n). Despite these unusual 

### 9 findings for the cool season, they were similar to findings from another study of 

### 10
Los Angeles area adults with asthma, which indicated an O 3 - associated decrease in 

### 11 indoor activity during the fall season ( Eiswerth et al., 2005 )

. 

### 12

In a cool season (September

- December) study conducted in older adults (ages 54

- 

### 13
91 years) in Steubenville, OH, Adamkiewicz et al. (2004 ) found that increases in O 3 

### 14 (1

- h avg an d 24

- h avg before eNO collection) were associated with decreases in eNO, 

### 15 reflecting decreases in pulmonary inflammation ( Figure 6

- 10 and 

### 16

Table 6

- 17 ). The study included healthy adults and those with asthma or COPD. A study 

### 17 in a subset of these adults illustrated why it is difficult to detect effects with central site 

### 18
O 3 concentrations in the cool season by showing that subjects spent ≥ 90% of time 

### 19
indoors and >77% at home and had a mean 24

- h avg O 3 personal

- ambient ratio of 0.27 

### 20 ( Sarnat et al., 2006a )

. 

### 21

Confounding in Epidemiologic Studies of Pulmonary Inflammation and Oxidative Stress

Except where noted in the preceding text; epidemiologic studies of pulmonary 

### 22 inflammation and oxidative stress accounted for potential confounding by meteorological 

### 23
facto rs. Increases in ambient O 3 concentration were associated with pulmonary 

### 24 inflammation or oxidative stress in models that adjusted for temperature and/or humidity 

### 25 ( Delfino et al., 2010a ; Barraza

- Villarreal et al., 2008 ; Romieu et al., 2008 ) . Final results 

### 26
from Sienra

- Monge et al. (2004 ) and Berhane et al. (2 011 ) were not adjusted for 

### 27 temperature because associations were not altered by adjustment for temperature. Most 

### 28 studies conducted over multiple seasons adjusted for season or time trend. 

### 29

In evidence limited to a small number of studies conducted in Mex ico City, O 3 - associated 

### 30 pulmonary inflammation and oxidative stress were not found to be confounded by PM 2.5 

### 31
or PM 10 . These studies, which analyzed 8

- hour averages for both O 3 and PM, found 

### 32
robust associations for O 3 ( Barraza

- Villarreal et al., 2008 ; Romieu et al., 2008 ; Sienra



### 33 Monge et al., 2004 ) . Ozone and PM, both measured at central sites located within 5 km of 

### 34

### Draft

– Do Not Cite or Quote 6

- 94 June 2012 subjects’ schools or homes, were moderately correlated (r = 0.46

- 0.54). Weak 

### 1
correlations have been found between personal exposures of O 3 and PM 2.5 

### 2 (Section 4.3.4.1 ). Only Romieu et al. (2008 ) provided quantitative results. Lag 0 of 

### 3
8

- h max O 3 was associated with the same magnitude of increase in MDA without and 

### 4 with adjustment for lag 0 of 8

- h max PM 2.5 (ra tio of geometric means for a 30

- ppb 

### 5 increase: 1.3 [95% CI: 1.0, 1.7]). In comparison, the O 3 - adjusted effect estimate for PM 2.5 

### 6
was cut in half. 

### 7

Summary of Epidemiologic Studies of Pulmonary Inflammation and Oxidative Stress

Many epidemiologic studies prov ided evidence that short

- term increases in ambient O 3 

### 8 exposure increase pulmonary inflammation and oxidative stress in children with asthma, 

### 9 with evidence primarily provided by studies conducted in Mexico City. By also finding 

### 10
that associations were attenu ated with higher antioxidant intake, these studies indicated 

### 11
that inhaled O 3 may be an important source of ROS in airways and/or may increase 

### 12 pulmonary inflammation via oxidative stress

- mediated mechanisms. Studies found 

### 13
O 3 - associated increases in pulmonar y inflammation in children with allergy ( Berhane et 

### 14 al., 2011 ; Barraza

- Villarreal et al., 2008 ) . The limited available evidence in children and 

### 15 adults with increased outdoor exposures an d older adults was inconclusive. Temperature 

### 16 and humidity were not found to confound O 3 associations. Copollutant models were 

### 17 analyzed in a few studies conducted in Mexico City; O 3 effect estimates were robust to 

### 18 adjustment for moderately correlated (r = 0 .46

- 0.54) PM 2.5 or PM 10 ( Barraza

- Villarreal et 

### 19 al., 2008 ; Romieu et al., 2008 ; Sienra

- Monge et al., 2004 )

. 

### 20

Ozone

- associated increases in pulmonary inflammation and oxidative stress were found 

### 21 in studies that used varied exposure assessment methods: measurement on sit e of 

### 22 subjects’ outdoor activity ( Nickmilder et al., 2007 ) , average of concentrations measured 

### 23
at the closest site each hour Khatri et al. (2009 ) , measurement at a site within 5 km of 

### 24 subjects’ schools or homes ( Barraza

- Villarreal et al., 2008 ; Romieu et al., 2008 ; Sienra



### 25 Monge et al., 2004 ) , and measurement at single site per town ( Berhane et al., 2011 )

. 

### 26 While these methods may differ in the degree of exposure measurement error, in the 

### 27 limited body of evidence, there was not a clear indication that the method of exposure 

### 28 assessment influenced the strength or magnitude of associations. 

### 29

Most studies examined and found associations with 8

- h max or daytime 8

- h avg O 3 

### 30 concentrations, although associations we re found for 1

- h max ( Nickmilder et al., 2007 ) 

### 31
and 24

- h avg O 3 ( Delfino et al., 2010a ) . Collectively, studies examined single

- day O 3 

### 32 concentrations lagged from 0 to 5 days and concentrations averaged o ver 2 to 9 days. Lag 

### 33
0 of 8

- h max O 3 was most frequently examined and consistently associated with 

### 34

### Draft

– Do Not Cite or Quote 6

- 95 June 2012 pulmonary inflammation and oxidative stress. However, in the few studies that examined 

### 1 multiple O 3 lags, multiday average 8

- h max or 8

- h avg concentrations w ere associated 

### 2 with larger increases in pulmonary inflammation and oxidative stress ( Berhane et al., 

### 3
2011 ; Delfino et al., 2010a ; Sienra

- Monge et al., 2004 ) . These findings for m ultiday 

### 4 average O 3 concentrations are supported by controlled human exposure (Section 6.2.3.1 ) 

### 5 and animal studies (Section 6.2.3.3 ) that similarly have found that some markers of 

### 6 pulmonary inflammation remain elevated with O 3 exposures repeated over multiple days. 

### 7

Several epidemiologic studies concurrently examined associations of ambient O 3 

### 8 concentrations with biological markers of pulmonary inflammation and lung function or 

### 9

re spiratory symptoms. Whether evaluated at the same or different lags of O 3 , associations 

### 10 generally were stronger for biological markers of airway inflammation than for lung 

### 11
function ( Khatri et al., 2009 ; Barraza

- Villarreal et al., 2008 ; Nickmilder et al., 2007 )

. 

### 12 Controlled human exposure studies also have demonstrated a lack of correlation between 

### 13 inflammatory and spirometric responses induced b y O 3 exposure (Section 6.2.3.1 ). 

### 14 Evidence has suggested that O 3 - related respiratory morbidity may occur via multiple 

### 15 mechanisms with varying time courses of action, and the examination of a limited 

### 16
number of O 3 lags in these aforementioned studies may explain some of the 

### 17
inconsistencies in associations of O 3 with measures of pulmonary inflammation and lung 

### 18 function. In contrast, based on examination in a few studies, increases in ambient O 3 

### 19 concentration were associated concurrently (at the same lag) with increases in pulmonary 

### 20 inflammation and increases in respiratory symptoms or activity limitations in the same 

### 21 population of individuals with asthma ( Khatri et al., 2009 ; Barraza

- Villarreal et al., 

### 22
2008 )

. 

### 23

6.2.3.3 Toxicology: Inf lammation and Injury

The 2006 O 3 AQCD states that the “extensive human clinical and animal toxicological 

### 24 evidence, together with the limited available epidemiologic evidence, is clearly indicative 

### 25
of a causal role for O 3 in inflammatory responses in the ai rways” ( U.S. EPA, 2006b )

. 

### 26 Airway ciliated epithelial cells and Type 1 cells are the most O 3 - sensitive cells and are 

### 27 initial targets of O 3 . These cells are damaged by O 3 and produce a number of 

### 28

pro

- inflammatory mediators (e.g., interleukins [IL

- 6, IL

- 8], PGE 2 ) capable of initiating a 

### 29 cascade of events leading to PMN i nflux into the lung, activation of alveolar 

### 30 macrophages, inflammation, and increased permeability across the epithelial barrier. One 

### 31 critical aspect of inflammation is the potential for metaplasia and alterations in 

### 32 pulmonary morphology. Studies have obser ved increased thickness of the alveolar septa, 

### 33 presumably due to increased cellularity after acute exposure to O 3 . Epithelial hyperplasia 

### 34 starts early in exposure and increases in magnitude for several weeks, after which it 

### 35

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– Do Not Cite or Quote 6

- 96 June 2012 plateaus until exposure ceases. When exposure persists for a month and longer, excess 

### 1 collagen and interstitial fibrosis are observed. This response, discussed in Chapter 7
, 

### 2
contin ues to increase in magnitude throughout exposure and can even continue to 

### 3 increase after exposure ends ( Last et al., 1984 ) . Previously reviewed toxicological studies 

### 4 of the ability of O 3 to cause inflammation, injury, and morphological changes are 

### 5
described in Table 6

- 5 on page 6

- 25 ( U.S. EPA, 1996f ) and Table 6

- 10 ( U.S. EPA, 

### 6 1996k ) and Table 6

- 11 ( U.S. EPA, 1996l ) beginning on page 6

- 61 of the 1996 O 3 AQCD, 

### 7
and Tables AX5

- 8 ( U.S. EPA, 2006d ) and AX5

- 9 ( U.S. EPA, 2006e ) , beginning on page 

### 8
AX5

- 17 of the 2006 O 3 AQCD. Numerous recent in vitro and in vivo studies add to this 

### 9 very large body of evidence for O 3 - induced inflammation and injury, and provide new 

### 10 information regarding the underlying mechanisms (see Section 5.3 ). 

### 11

A number of species, including dogs, rabbits, guinea pigs, rats, and mice have been used 

### 12 as models to study the pulmonary effects of O 3 , but the similarity of non

- human primates 

### 13 to humans makes them an attractive model in which to study the pulmonary response to 

### 14
O 3 . As reviewed in the 1996 and 2006 O 3 AQCDs, several pulmonary effects, including 

### 15 inflammation, changes in morphometry, and airway hyperresponsiveness, have been 

### 16 observed in macaque and rhesus monkeys after acute exposure to O 3 ( Table 6

- 18 presents 

### 17 a highlight of these studies). Increases in inflammatory cells were observed after a single 

### 18
8

- h exposure of adult rhesus monkeys to 1 ppm O 3 ( Hyde et al., 1992 ) . Inflammation was 

### 19 linked to morphometric changes, such as increases in necrotic cel ls, smooth muscle, 

### 20 fibroblasts, and nonciliated bronchiolar cells, which were observed in the trachea, 

### 21 bronchi, or respiratory bronchioles. Effects have also been observed after short

- term 

### 22 repeated exposure to O 3 at concentrations that are more relevant to ambient O 3 

### 23 concentrations. Morphometry changes in the lung, nose, and vocal cords were observed 

### 24 after exposure to 0.15 ppm O 3 for 8

- h/day for 6 days ( Harkema et al., 1993 ; Dimitriadis, 

### 25
1992 ; Harkema et al., 1987a ) . Since 2006, however, only one study has been published 

### 26 regarding acute exposure of non

- human primates to O 3 (a number of recent chronic 

### 27
studies in non

- human primates are described in Chapter 7 ). In this study, a single 6

- hour 

### 28 exposure of adult male cynomolgus monkeys to 1 ppm O 3 induced significa nt increases 

### 29 in inflammatory and injury mar kers, including BAL neutrophils, total protein, alkaline 

### 30 phosphatase, IL

- 6, IL

- 8, and G

- CSF ( Hicks et al., 2010a ) . Gene expression analysis 

### 31 confirmed the increases in the pro

- inflammatory cytokine IL

- 8, which had been 

### 32 previously described in O 3 exposed rhesus monkeys ( Chang et al., 1998 ) . The 

### 33
anti

- inflammat ory cytokine IL

- 10 was also elevated, but the fold changes in IL

- 10 and 

### 34
G

- CSF were relatively low and highly variable. The single exposure also caused necrosis 

### 35 and sloughing of the epithelial lining of the most distal portions of the terminal 

### 36
bronchioles a nd the respiratory bronchioles. Bronchiolitis, alveolitis, parenchymal and 

### 37 centriacinar inflammation were also observed. A second exposure protocol (two 

### 38 exposures with a 2

- week inter

- exposure period) resulted in similar inflammatory 

### 39

### Draft

– Do Not Cite or Quote 6

- 97 June 2012 responses, with the exc eption of total protein and alkaline phosphatase levels which were 

### 1 attenuated, indicating that attenuation of some but not all lavage parameters occurred 

### 2 upon repeated exposure of non

- human primates to O 3 ( Hicks et al., 2010a ) . This 

### 3 variability in attenuation is similar to the findings of earlier reports in rodents ( Wiester et 

### 4 al., 1996c ) and non

- human primates ( Tyler et al., 1988 )

. 

### 5

Table 6

- 18 describes key morphometric studies conducted in non

- human primates 

### 6 exposed to O 3 . Morphologic observations made by Dungworth (1976 ); ( 1975 ) indicate 

### 7
that the rat and Bonnet monkey ( Macaca radiata ) are approximately equal in 

### 8 susceptibility to short

- term effects of O 3 . Mild but discerni ble lesions were caused in both 

### 9 species by exposure to 0.2 ppm O 3 for 8 h/day for 7 days. The authors stated that 

### 10 detectable morphological effects in the rat occurred at levels as low as 0.1 ppm O 3 . In 

### 11 both species, the lesion occurred at the junction of the small airways and the gaseous 

### 12 exchange region. In rats, the pr ominent features were accumulation of macrophages, 

### 13 replacement of necrotic Type 1 epithelial cells with Type 2 cells, and damage to ciliated 

### 14 and nonciliated Clara cells. The principal site of damage was the alveolar duct. In 

### 15 monkeys, the prominent O 3 - induc ed injury was limited to the small airways. At 0.2 ppm 

### 16
O 3 , the lesion was observed at the proximal portion of the respiratory bronchioles. As 

### 17
concentrations of O 3 were increased up to 0.8 ppm, the severity of the lesion increased, 

### 18 and the damage extended d istally to involve the proximal portions of the alveolar duct. 

### 19 Mellick et al. (1977 ) found similar but more pronounced effects when rhesus monkeys (3 

### 20
to 5 years of age) were exposed to 0.5 and 0.8 ppm O 3 , 8 hours/day for 7 days. In these 

### 21 experiments, the respiratory bronchioles were the most severely damaged, and more 

### 22 distal parenchymal regions were unaffected. Major effects were hyperplasia and 

### 23 hypertrophy of the nonciliated bronchiolar epithelial cells and the accumulation of 

### 24 macrophages intraluminally. In mice, continuous exposure to 0.5 ppm O 3 caused nodular 

### 25 hyperplasia of Clara cells after 7 days of exposure. Similar findings were reported by 

### 26 Schwartz (1976 ) and Schwartz et al. (1976 ) , who exposed rats to 0.2, 0.5 or 0.8 ppm O 3 

### 27
for 8 or 24 hours/day for 1 week. Changes observed within the proximal alveoli included 

### 28 infiltration of inflammatory cells and swelling and necrosis of Type 1 cells. In the 

### 29 terminal bronchiole, the changes reported were shortened cilia, clustering of basal bodies 

### 30
in ciliated cells su ggesting ciliogenesis, and reduction in height or loss of cytoplasmic 

### 31 luminal projection of the Clara cells. Effects were seen at O 3 concentrations as low as 

### 32
0.2 ppm. A dose

- dependent pulmonary response to the three levels of O 3 was evident. No 

### 33
differences were observed in morphologic characteristics of the lesions between rats 

### 34 exposed continuously and those exposed intermittently for 8 hours/day. 

### 35

### Draft

– Do Not Cite or Quote 6

- 98 June 2012 Table 6

- 18 Morphometric observations in non

- human primates after acute
ozone exposure.

Reference O 3 concentration (ppm) Exposure duration Species, Sex, Age Observation

Harkema et al. (1993 ) 0.15 8 h/day for 6 days Macaca radiata (bonnet macaques) 2

- 6 years old Several fold increase in thickness of surface epithelium in respiratory bronchioles ; increase in interstitial mass with increase in proportion of cuboidal cells. Harkema et al. (1987a ); ( 1987b ) 0.15 8 h/day for 6 days Macaca radiata
, M, F 2

- 6 years old Ciliated cell necrosis, shortened cilia, and increased mucous cells in the respiratory epithelium of nose after 0.15 ppm; changes in nonciliated cells, intraepithelial leukocytes, and mucous cells in the transitional epithelium Dungworth (1976 ) 0.2 0.5 0.8 8 h/day for 7 days for monkey and rat; continuous at 0.5 ppm for 7 days for mouse Adult Rhesus and bonnet monkeys; S

- D rats; Mice In both rats and monkeys mild but discerni ble lesions were observed at 0.2 ppm; similar severity between species but different site of lesions

– respiratory bronchioles for monkey and damage to ciliated, Clara, and alveolar epithelial cells for rat; Clara cell hyperplasia in mice

Leonard et al. (1991 ) 0.25 8 h/day for 7 days Macaca radiata age not specified The O 3 exposure level is not clear

– the abstract states 0.64 ppm, but the text mentions only 0.25 ppm. Morphometric changes in vocal cord mucosa: disruption and hyperplasia of stratified squamous epithelium; epithelial and connective tissue thickness increased Chang et al. ( 1998 ) 0.96 8 h Rhesus, M age not specified Increase in IL

- 8 in airway epithelium correlated with PMN influx
Hyde et al. (1992 ) 0.96 8 h Rhesus, M 2

- 8.5 years old Increased PMNs; morphometric changes in trachea, conducting airways, respiratory bronchioles including increased smooth muscle in bronchi and RB. Hicks et al. (2010b ) 1.0 6 h Cynomolgus, M 5

- 7 kg (Adult) Increase in PMNs and IL

- 8 in lavage fluid

Exposure of adult BALB/c mice to 0.1 ppm O 3 for 4 hours increased BAL levels of 

### 1 keratinocyte chemoattractant (KC; IL

- 8 homologue) (~ fold), IL

- 6 (~12

- fold), and TNF

- α 

### 2 (~ 2

- fold) ( Damera et al., 2010 ) . Additionally, O 3 increased BAL neutrophils by 21% 

### 3 without changes in other cell types. A trend of increased neutrophils with increased O 3 

### 4 concentration (0.12

- 2 ppm) was observed in BALB/c mice exposed for 3 hours ( Jang et 

### 5 al., 2005 ) . Although alterations in the epithelium of the airways were not evident in 129J 

### 6
mice after 4 hours of exposure to 0.2 ppm O 3 ( Plopper et al., 2006 ) , detachment of the 

### 7 bronchiolar epithelium was observed in SD rats after 5 days or 60 days of exposure to 

### 8
0.25 ppm O 3 ( Oyarzún et al., 2005 ) . Subacute (65 hours) exposure to 0.3 ppm O 3 induced 

### 9 pulmonary inflammation, cytokine induction, and enhanced vascular permeability in wild 

### 10 type mice of a mixed background (129/Ola and C57BL/6) and these effects were 

### 11
exacerbated in metallothionein I/II knockout mice ( Inoue et al., 2008 ) . Three hours or 

### 12
72 hours of exposure to 0.3 ppm O 3 resulted in similar levels of IL

- 6 expression in the 

### 13 lungs of C57BL/6 mice ( Johnston et al., 2005b ) , along with increases in BAL protein, 

### 14

### Draft

– Do Not Cite or Quote 6

- 99 June 2012 sTNFR1, and sTNFR2. Increased neutrophils were observed only after the 72

- hour 

### 1 exposure, and neither exposure resulted in detectable levels of IL

- 6 or KC protein. Levels 

### 2 of BAL protein, sTNFR1, and sTNFR2 were higher in the 72

- hour exposure group than 

### 3
in the 3

- hour exposure group. In another study, the same subacute (72 hours) exposure 

### 4 protocol elicited increases in BALF protein, IP

- 10, sTNFR1, macrophages, neutrophils, 

### 5
and IL

- 6, IL

- 1α, and IL

- 1β expression ( Johns ton et al., 2007 )

. Yoon et al. (2007 ) exposed 

### 6
C57BL/6J mice continuous ly to 0.3 ppm O 3 for 6, 24, 48, or 72 hours, and observed 

### 7 elevated levels of KC, MIP

- 2, metalloproteinases, and inflammatory cells in the lungs at 

### 8 various time points. A similar exposure protocol using C3H/HeJ and C3H/OuJ mice 

### 9 demonstrated elevations in pr otein, PMNs, and KC, which were predominantly TLR 4 

### 10 pathway dependent based on their prominence in the TLR 4 sufficient C3H/OuJ strain 

### 11 Bauer et al. (2011 )

. C3H/OuJ mice also had elevated levels of the heat

- shock protein 

### 12 HSP70, and further experiments in HSP70 deficient mice indicated a role for this 

### 13 particular pathway in O 3 - related injury, discussed in more detail in Chapter 5

. 

### 14

As reviewed in the 2006 O 3 AQCD, the time course for changes in BAL depends on the 

### 15 parameters being studied. Similarly, after exposing adult C57BL mice to 0.5 ppm O 3 for 

### 16
3 hours, Han et al. (2008 ) observed early (5 hours postexposure) increases in BAL TNF

- α 

### 17

an d IL

- 1β, which diminished by 24 hours postexposure. Total BAL protein was elevated 

### 18
at 24 hours, but there were only minimal or negligible changes in LDH, total cells, or 

### 19 PMNs. Ozone increased BAL mucin levels (with statistical significa nce by 24 hours 

### 20 post exposure), and significa ntly elevated surfactant protein D at both time points. Prior 

### 21 intratracheal (IT) exposure to multiwalled carbon nanotubes enhanced most of these 

### 22 effects, but the majority of responses to the combined exposure were not greater than 

### 23

t hose to nanotubes alone. Ozone exposure did not induce markers of oxidative stress in 

### 24 lung tissue, BAL, or serum. Consistent with this study, Aibo et al. (2010 ) did not detect 

### 25 changes in BAL inflammatory cell numbers in the same mouse strain after a 6

- hou r 

### 26 exposure to 0.25 or 0.5 ppm. The majority of inflammatory cytokines (pulmonary or 

### 27 circulating) were not significa ntly changed (as assessed 9 hours post

- O 3 exposure). 

### 28 Exposure of C57BL/6 mice to 1 ppm for 3 hours increased BAL total cells, neutrophils, 

### 29

an d KC; these responses were greatest at 24 hours postexposure. F2

- isoprostane 

### 30 (8

- isoprostane), a marker of oxidative stress, was also elevated by O 3 , peaking at 

### 31
48 hours postexposure ( Voynow et al., 2009 )

. 

### 32

Atopic asthma appears to be a risk factor for more severe O 3 induced airway 

### 33
inflammation in humans ( Balmes et al., 1997 ; Scannell et al., 1996 ) , and allergic animal 

### 34 models are often used to investigate the effects of O 3 on this potentially at

- risk 

### 35 population. Farraj et al. (2010 ) exposed allergen

- sensitized adult male BALB/c mice to 

### 36
0.5 ppm O 3 for 5 hours once per week for 4 weeks. Ovalbumin

- sensitized mice exposed 

### 37
to O 3 had significa ntly increased BAL eosinophils by 85% and neutrophils by 103% 

### 38

### Draft

– Do Not Cite or Quote 6

- 100 June 2012 relative to OVA sensitized mice exposed to air, but these changes were not evident upon 

### 1 histopathological evaluation of the lung, and no O 3 induced lesions were evident in the 

### 2 nasal passages. Ozone increased BAL levels of N

- acetyl

- glucosaminidase (NAG; a 

### 3 marker of injury) and protein. DEP co

- exposure (2.0 mg/m 3 , nose only) inhibited these 

### 4 responses. These pro

- inflammatory effects in an allergic mouse model have also been 

### 5
observed in rats. Wa gner et al. (2007 ) exposed the relatively O 3 - resistant Brown Norway 

### 6
rat strain to 1 ppm O 3 after sensitizing and challenging with OVA. Rats were exposed for 

### 7
2 days, and airway inflammation was assessed one day later. Filtered air for controls 

### 8
contained less than 0.02 ppm O 3 . Histopathology indicated O 3 induced site

- specific lung 

### 9 lesions in the centriacinar regions, characterized by wall thickening partly due to 

### 10 inflammatory cells influx. BAL neutrophils were elevated by O 3 in allergic rats, and 

### 11 modestly increased in non

- allergic animals (not significa nt). A slight (but not significa nt) 

### 12 increase in macrophages was observed, but eosinophil numbers were not affected by O 3 . 

### 13 Soluble mediators of inflammation (Cys

- LT, MCP

- 1, and IL

- 6) were elevated by O 3 in 

### 14
all ergic animals but not non

- allergic rats. Treatment with γT, which neutralizes oxidized 

### 15 lipid radicals and protects lipids and proteins from nitrosative damage, did not alter the 

### 16 morphologic character or severity of the centriacinar lesions caused by O 3 , no r did it 

### 17 reduce neutrophil influx. It did, however, significa ntly reduce O 3 - induced soluble 

### 18 inflammatory mediators in allergic rats. The effects of O 3 in animal models of allergic 

### 19
asthma are discussed in Section 6.2.6

. 

### 20

In summary, a large number of toxicology studies have demonstrated that acute exposure 

### 21
to O 3 produces injury and inflammation in the mammalian lung, supporting the 

### 22 observations in controlled human exposure studies (Section 6.2.3.1 ). These a cute 

### 23 changes, both in inflammation and morphology, provide a limited amount of evidence for 

### 24 long term sequelae of exposure to O 3 . Related alterations resulting from long term 

### 25 exposure, such as fibrotic changes, are discussed in Chapter 7

. 

### 26

6.2.4 Respiratory Symptoms and Medication Use

Controlled human exposure and toxicological studies have described modes of action 

### 27 through which short

- term O 3 exposure may increase respiratory symptoms by 

### 28 demonstrating O 3 - induced airway hyperresponsiveness (Section 6.2.2 ) and pulmonary 

### 29 inflammation (Section 6.2.3.1 and Section 6.2.3.3 ). Epidemiologic studi es have not 

### 30 widely examined associations between ambient O 3 concentrations and airway 

### 31 hyperresponsiveness but have found O 3 - associated increases in pulmonary inflammation 

### 32 and oxidative stress (Section 6.3.2.2 ). In addition to lung function decrements, controlled 

### 33 human exposure studies clearly indicate O 3 - induced increases in respiratory symptoms 

### 34 including pain on deep inspiration, shortness of breath, and cough. This evidence is 

### 35

### Draft

– Do Not Cite or Quote 6

- 101 June 2012 detailed in Section 6.2.1.1 ; however, salient observations include an increase in 

### 1 respiratory symptoms with increasing concentration and duration of O 3 exposure and 

### 2 activity level of exposed subjects ( McDonnell et al., 1999b ) . Further, increases in total 

### 3

s ubjective respiratory symptoms have been reported following 5.6 and 6.6 hours of 

### 4 exposure to 60 ppb O 3 relat ive to baseline ( Adams, 2006a )

. At 70 ppb, Schelegle et al. 

### 5 (2009 ) observed a statistically significa nt O 3 - induced FEV 1 decrement of 6.1% at 6.6 

### 6
hours and a significa nt increase in total subjective symptoms at 5.6 and 6.6 hours. The 

### 7 findings for O 3 - induced respiratory symptoms in controlled human exposure studies and 

### 8 the evidence integrated across disciplines describing underlying modes of action provide 

### 9 biological plausibility for epidemiologic associations observed be tween short

- term 

### 10
increases in ambient O 3 concentration and increases in respiratory symptoms. 

### 11

In epidemiologic studies, respiratory symptom data typically are collected by having 

### 12 subjects (or their parents) record symptoms and medication use in a diary wit hout direct 

### 13 supervision by study staff. Several limitations of symptom reports are well recognized: 

### 14 recall error if not recorded daily, differences among subjects in the interpretation of 

### 15 symptoms, differential reporting by subjects with and without asthma , and occurrence in 

### 16 a smaller percentage of the population compared with changes in lung function and 

### 17 biological markers of pulmonary inflammation. Nonetheless, symptom diaries remain a 

### 18
convenient tool to collect individual

- level data from a large number o f subjects and allow 

### 19 modeling of associations between daily changes in O 3 concentration and daily changes in 

### 20 respiratory morbidity. Importantly, most of the limitations described above are sources of 

### 21
random measurement error that can bias effect estimates to the null or increase the 

### 22 uncertainty around effect estimates. Furthermore, because respiratory symptoms are 

### 23 associated with limitations in activity and function and are the primary reason for using 

### 24 medication and seeking medical care, the evidence is di rectly coherent with the consistent 

### 25
associations observed between increases in ambient O 3 concentration and increases in 

### 26 asthma ED visits (Section 6.2.7.3 ). 

### 27

Most studies were conducted in individuals with asthma, and as was concluded in the 

### 28
2006 O 3 AQCD ( U.S. EPA, 2006b
, 1996a ) , the collective body of epidemiologic 

### 29
evidence indicates that short

- term increases in ambient O 3 concentrations are associated 

### 30 with increases in respiratory symptoms in c hildren with asthma. Studies also found 

### 31
O 3 - associated increases in the use of asthma medication in children. In a smaller body of 

### 32 studies, increases in ambient O 3 concentration were associated with increases in 

### 33 respiratory symptoms in adults with asthma. O zone

- associated increases in respiratory 

### 34 symptoms in healthy populations were not as clearly indicated. 

### 35

### Draft

– Do Not Cite or Quote 6

- 102 June 2012 6.2.4.1 Children with Asthma

Respiratory Symptoms

Table 6

- 19 presents the locations, time periods, and ambient O 3 concentrations for studies 

### 1 examining respiratory symptoms and medication use in children with asthma. The 

### 2 evidence supporting associations between short

- term increases in ambient O 3 

### 3 concentration and increases in respiratory symptoms in children with asthma is derived 

### 4 mostly from examination of 1

- h max, 8

- h max, or 8

- h avg O 3 concentrations and strong 

### 5 findings from a large body of single

- region or single

- city studies ( Figure 6

- 11 and 

### 6
Table 6

- 20 ). The few available U.S. multicit y studies produced less consistent 

### 7
associations. 

### 8

Similar to lung function, associations with respiratory symptoms in children with asthma 

### 9
were found with ambient O 3 concentrations assigned to subjects using various methods 

### 10 with potentially different degree s of exposure measurement error. As was discussed for 

### 11 lung function, methods included measurement of O 3 on site of and at the time of outdoor 

### 12 activity ( Thurston et al., 1997 ) , which is associated with higher ambient

- personal O 3 

### 13 correlations and ratios (Section 4.3.3 ); O 3 concentrations mea sured at sites within 5 km of 

### 14 subjects’ home or school ( Escamilla

- Nuñez et al., 2008 ; Romieu et al., 2006 ; 1997 ; 

### 15
1996 ) ; O 3 measured at a single city site ( Gielen et al., 1997 ) ; and O 3 concentrations 

### 16 averaged across multiple sites ( Gent et al., 2003 ; Mortimer et al., 2002 ) . In analys es with 

### 17
O 3 averaged across multiple sites, which were restricted to warm seasons, O 3 

### 18 concentrations within the region were temporally correlated as indicated by high 

### 19 statewide correlations [median r = 0.83 in Gent et al. (2003 ) ] or similar odds ratios for O 3 

### 20 averaged across all within

- city monitors and that averaged from the three closest sites 

### 21 ( Mortimer et al., 2002 ) . In these panel studies, the averaged ambient concentrations may 

### 22 have well represented the temporal variability in subjects’ ambient O 3 exposures. 

### 23

### Draft

– Do Not Cite or Quote 6

- 103 June 2012 Table 6

- 19 Mean and upper percentile ozone concentrations in epidemiologic studies of respiratory symptoms, medication use, and activity levels in children with asthma

. Study * Location Study Period O 3 Averaging Time Mean /Median Concentration (ppb) Upper Percentile Concentrations (ppb)

Thurston et al. (1997 ) CT River Valley, CT June 1991

- 1993 1

- h max 83.6 a Max: 160 a

Escamilla

Nuñez et al. (2008 ) Mexico City, Mexico July

- March 2003

- 2005 1

- h max 86.5 NR

2006 ) Mexico City, Mexico October 1998

- April 2000 8

- h max 1

- h max 69 102 Max: 184 Max: 309

1997 ) Southern Mexico City, Mexico April

- July 1991; November 1991

- February 1992 1

- h max 196 Max: 390

Romieu et al. (1996 ) Northern Mexico City, Mexico April

- July 1991; November 1991

- February 1992 1

- h max 190 Max: 370

Gent et al. (2003 ) CT, southern MA April

September 2001 8

- h rolling avg 1

- h max 51.3, 50.0 (median) 58.6, 55.5 (median) Max: 99.6 Max: 125.5

Mortimer et al. (2002 ); ( 2000 ) Bronx, East Harlem, NY; Baltimore, MD; Washington, DC; Detroit, MI, Cleveland, OH; Chicago, IL; St. Louis, MO ; (NCICAS) June

- August 1993 8

- h avg (10 a.m.

- 6 p.m.) 48 NR

Gielen et al. (1997 ) Amsterdam, Netherlands April

- July 1995 8

- h max 34.2 b Max: 56.5 b

Delfino et al. (2003 ) Los Angeles, CA November 1999

- January 2000 8

- h max 1

- h max 17.1 25.4 90th: 26.1, Max: 37 90th: 38.0, Max: 52

Rabinovitch et al. (2004 ) Denver, CO November

March 1999

- 2002 1

- h max 28.2 75th: 60, Max: 70.0

Schildcrout et al. (2006 ) Albuquerque, NM; Baltimore, MD; Boston, MA; Denver, CO; San Diego, CA; Seattle, WA; St. Louis, MO; Toronto, ON, Canada (CAMP) May

September 1994

- 1995 1

- h m ax Range in medians across cities: 43.0

- 65.8 Range in 90th across cities: 61.5

- 94.7

Jalaludin et al. (2004 ) Sydney, Australia February

December 1994 15

- h avg (6 a.m.
- 9

p.m.) 12 Max: 43

### Draft

– Do Not Cite or Quote 6

- 104 June 2012 Study * Location Study Period O 3 Averaging Time Mean /Median Concentration (ppb) Upper Percentile Concentrations (ppb)

O'Connor et al. (2008 ) Boston, MA; Bronx, Manhattan NY; Chicago, IL; Dallas, TX, Seattle, WA; Tucson, AZ (ICAS) August 1998

- July 2001 24

- h avg NR NR

Ostro et al. (2001 ) Los Angeles, CA August

October 1993 1

- h max Los Angeles: 59.5 Pasadena: 95.8 Max: 130 Max: 220

Mann et al. (2 010 ) Fresno/Clovis, California Winter

Summer 2000

- 2005 8

- h max 49.4 (median) 75th: 69.5, Max: 120.0

Just et al. (2002 ) Paris, France April

- June 1996 24

- h avg 30.0 b Max: 61.7 b

* Note: Studies presented in order of first appearance in the text of this section. NCICAS = National Cooperative Inner

- City Asthma Study, NR = Not Reported, ICAS = Inner City Asthma Study, CAMP = Childhood Asthma Management Program.

a Measured on site of subjects’ outdoor activity.

b Concentrations converted from μg/m 3 to ppb using the conversion factor of 0.51 assumi ng standard temperature (25°C) and pressure (1 atm).

### Draft

– Do Not Cite or Quote 6

- 105 June 2012 Note: Results are presented first for aggregate indices of symptoms then for individual symptoms. Within each category, resul ts generally are organized in order of increasing mean ambient O 3 concentra tion. LRS = lower respiratory symptoms, URS = upper respiratory symptoms. Odds ratios are from single

- pollutant models and are standardized to a 40

- , 30

- , and 20

- ppb increase for 1

- h max, 8

- h max (or 8

- h avg or 15

- h avg), and 24

- h avg O 3 concentrations, re spectively.


### Figure 6

- 11 Associations between ambient ozone concentrations and respiratory symptoms in children with asthma. Study Aggregate of symptoms

Rabinovitch et al. (2004) Delfino et al. (2003)

Schildcrout et al. (2006)

Gielen et al. (1997)

Mortimer et al. (2002)

Mortimer et al. (2000)

Romieu et al. (1996) Romieu et al. (1997) Individual symptoms Jalaludin et al. (2004)

O'Connor et al. (2008)

Ostro et al. (2001) Escamilla

- Nunez et al. (2008) Mann et al. (2010)

Thurston et al. (1997) Romieu et al. (2006) Symptom

Daytime symptoms Bothersome symptoms

Asthma symptoms

LRS URS Morning symptoms

LRS

LRS

Wheeze

Wheeze/cough Noctural cough

Wheeze Cough

Wheeze

Chest symptoms Difficulty breathing O 3 Lag

0

- 2 avg 0, 8

- h max 0, 1

- h max

0 0

- 2 avg

0

1 2 3 4

1

- 4 avg

0

0

0 2

1

- 19 avg

0

3

1

0

0

0

- 5 avg Subgroup

All subjects All subjects All subjects All subjects All subjects No medication Cromolyn use Beta

- agonist/xanthine use Steroid use Without allergy With allergy

All Fungi allergic

GSTM1 positive GSTM1 null GSTP1 Ile/Ile or Ile/Val GSTP1 Val/Val ►

►

0 0.5 1 1.5 2 2.5 Odds ratio (95% CI)

### Draft

– Do Not Cite or Quote 6

- 106 June 2012 Table 6

- 20 Additional characteristics and quantitative data for studies presented in Figure 6

- 11.

Study * Location/Population O 3 Averaging Time O 3 Lag Symptom Subgroup Standardized OR (95% CI) a

Studies examining aggregates of symptoms

Delfino et al. (2003 ) Los Angeles, CA 22 children with asthm a, ages 10

- 16 yr 8

- h max 1

- h max 0 Bothersome symptoms 0.75 (0.24, 2.30) 1.09 (0.39, 3.03)

Rabinovitch et al. (2004 ) Denver, CO 86 children with asthma, ages 6

- 12 yr 1

- h max 0

- 2 avg Daytime symptoms 1.32 (1.01, 1.74)

Schildcrout et al. (2006 ) Albuquerque, NM; Baltimore, MD; Boston, MA; Denver, CO; San Diego, CA; Seattle, WA; St. Louis, MO; Toronto, ON, Canad a 990 children with asthma, ages 5

- 12 yr 1

- h max 0 0

- 2 avg Asthma symptoms 1.08 (0.89, 1.31) 1.01 (0.92, 1.12)

Gielen et al. (1997 ) Amsterdam, Netherlands 61 children with asthma, ages 7

- 13 yr 8

- h max 0 LRS URS 1.04 (0.75, 1.45) 1.16 (1.02, 1.32)

( 2002 ); Mortimer et al. (2000 ) Bronx, East Harlem, NY; Baltimore, MD; Washington, DC; Detroit, MI, Cleveland, OH; Chicago, IL; St. Louis, MO
846 c hildren with asthma, ages 4

- 9 yr 8

- h avg (10 a.m.

- 6 p.m.) 1
2 3 4
1

- 4 avg Morning symptoms All subjects All subjects All subjects All subjects All subjects No medication
use Cromolyn use β

agonist/xanthine
use Steroid use Without allergy With allergy 1.06 (0.88, 1.27) 1.21 (1.04, 1.41) 1.02 (0.88, 1.18) 1.19 (1.02, 1.38) 1.35 (1.04, 1.74) 1.08 (0.62, 1.87 2.13 (1.12, 4.04) 1.39 (0.98, 1.98) 1.17 (0.79, 1.72) 1.59 (1.00, 2.52) 1.35 (0.92, 1.96)

Romieu et al. (1996 ) northern Mexico City, Mexico 71 children with asthma, ages 5

- 7 yr 1

- h max 0 LRS 1.07 (1.02, 1.12)

Romieu et al. (1997 ) southern Mexico City, Mexico 65 children with asthma, ages 5

- 13 yr 1

- h max 0 LRS 1.09 (1.04, 1.14)

Studies examining individual symptoms

Jalaludin et al. (2004 ) Sydney, Australia 125 children with asthma, mean age 9.6 yr 15

- h avg (6 a.m.
- 9 p.m.) 0
2 Wheeze 0.93 (0.63, 1.37) 1.15 (0.94, 1.41)

O'Connor et al. (2008 ) Boston, MA; Bronx, Manhattan NY; Chicago, IL; Dallas, TX, Seattle, WA; Tucson, AZ 861 children with asthma, mean (SD) age 7.7 (2.0) yr 24

- h avg 1

- 19 avg Wheeze/cough 1.02 (0.86, 1.21)

### Draft

– Do Not Cite or Quote 6

- 107 June 2012 Study * Location/Population O 3 Averaging Time O 3 Lag Symptom Subgroup Standardized OR (95% CI) a

Just et al. (2002 ) Paris, France 82 children with asthma, mean (SD) age 10.9 (2.5) yr 24

- h avg 0 Nocturnal cough incidence 1.17 (0.72, 1.91)

Ostro et al. (2001 ) Los Angeles, CA 138 children with asthma, ages 6

- 13 yr 1

- h max 3 Wheeze 0.95 (0.86, 1.04)

Escamilla

Nuñez et al. (2008 ) Mexico City, Mexico 147 children with asthma, mean age 9.6 yr 1

- h max 1 Wheeze 1.08 (1.03, 1.14)

Mann et al. (2010 ) Fresno/Clovia, California 280 children with asthma, ages 6

- 11 yr 8

- h max 0 Wheeze All Fungi allergic 1.00 (0.84, 1.19) 1.06 (0.84, 1.34)

Thurston et al. (1997 ) CT River Valley, CT 166 children with asthma, ages 7

- 13 yr 1

- h max 0 Chest symptoms 1.28 (1.09, 1.51)

Romieu et al. (2006 ) Mexico City, Mexico 151 children with asthma, mean age 9 yr 1

- h max 0

- 5 avg Difficulty breathing GSTM1 positive GSTM1 null GSTP1 Ile/Ile or Ile/Val GSTP1 Val/Val 1.10 (0.98, 1.24) 1.17 (1.02, 1.33) 1.06 (0.94, 1.20) 1.30 (1.10, 1.53)

Gent et al. (2003 ) b CT, southern MA 130 children with asthma on maintenance medication 1

- h max 0 Wheeze O 3 <43.2 ppb O 3 43.2

- 51.5 ppb O 3 51.6

- 58.8 ppb O 3 58.9

- 72.6 ppb O 3 ≥ 72.7 ppb 1.00 (reference) 1.04 (0.89, 1.21) 1.16 (1.00, 1.35) 1.16 (1.00, 1.35) 1.22 (0.97, 1.53)

Chest tightness O 3 <43.2 ppb O 3 43.2

- 51.5 ppb O 3 51.6

- 58.8 ppb O 3 58.9

- 72.6 ppb O 3 ≥ 72.7 ppb 1.00 (reference) 1.11 (0.91, 1.36) 1.01 (0.83, 1.23) 1.16 (0.97, 1.39) 1.31 (0.97, 1.77)

*Includes studies for Figure 6

- 11 , plus others. LRS = Lower respiratory symptoms, URS = Upper respiratory symptoms.

a Effect estimates are standardized to a 40, 30, and 20 ppb increase for 1

- h max, 8

- h max (or 8

- h avg or 15

- h avg), and 24

- h avg O 3 , respectively.

b Results not included in Figure 6

- 11 because results presented per quintile of ambient O 3 concentration.

Among U.S. multicity studies of children with asthma, each of which exam ined a 

### 1
different O 3 averaging time, O 3 was not consistently associated with increases in 

### 2 respiratory symptoms ( O'Connor et al., 2008 ; Schildcrout et al., 2006 ; Mortimer et al., 

### 3
2002 ) . In the NCICAS cohort (described in Section 6.2.1.2 ), increases in most evaluated 

### 4 lags of O 3 (1 to 4 and 1

- 4 avg) were associated with increases in asthma symptoms. A 

### 5
30

- ppb increase in lag 1

- 4 avg, of 8

- h avg (10 a.m.

- 6 p.m.), O 3 was associated with an 

### 6 increase in morning asthma symptoms with an OR of 1.35 (95% CI: 1.04, 1.69) 

### 7 ( Mortimer et al., 2002 ) . The OR was similar in an analysis restricted to O 3 concentrations 

### 8
<80 ppb. Associations were similarly strong for lags 2 and 4 of O 3 but weaker for lags 1 

### 9

### Draft

– Do Not Cite or Quote 6

- 108 June 2012 and 3 ( Figure 6

- 11 and Table 6

- 20 ). In the ICAS cohort (described in Section 6.2.1.2 ), 

### 1
associations of 19

- day avg of 24

- h avg O 3 with wheeze and nighttime asthma were 

### 2 positive and negative, respectively ( O'Connor et al., 2008 ) . NCICAS collected symptom 

### 3 data daily ( Mortimer et al., 2002 ; 2000 ) , whereas in ICAS, every 2 months, parents 

### 4 reported the number of days with symptoms over the previous 2 weeks ( O'Connor et al., 

### 5
2008 ) . Thus, ICAS was precluded from examining associations with single

- day O 3 

### 6 concentrations and shorter lag periods. 

### 7

Like NCICAS, the U.S. multicity Childhood Asthma Management Program (CAMP, 

### 8 with cities in common with NCICAS and ICAS, Table 6

- 19 ) collected daily symptom 

### 9 data, analyzed data collected between May and September, and evaluated multiple lags of 

### 10
O 3 ( Schildcrout et al., 2006 ) . However, associations in CAMP were weaker for all 

### 11 evaluated lags of O 3 . In meta

- analyses that combined city

- specific estimates, a 40

- ppb 

### 12 increase in lag 0 of 1

- h max O 3 was associated with asthma symptoms with an OR of 

### 13 1.08 (95% CI: 0.89, 1.31). Odds ratios for lags 1 and 2 and the 3

- day sum of O 3 were 

### 14 between 1.0 and 1.03. In this study, data available from an average of 12 subjects pe r day 

### 15 per city were used to produce city

- specific ORs. These city

- specific ORs then were 

### 16
combined in meta

- analyses to produce study

- wide ORs. Because O 3 analyses were 

### 17 restricted to warm seasons, there likely was less power to detect associations with O 3 th an 

### 18 with other pollutants, which were analyzed using year

- round data. 

### 19

Several longitudinal studies conducted in different cohorts of children with asthma in 

### 20
Mexico City, Mexico examined and found increases in respiratory symptoms in 

### 21
association with 1

- h ma x O 3 concentrations ( Escamilla

- Nuñez et al., 2008 ; Romi eu et al., 

### 22
2006 ; 1997 ; 1996 )

. 1997 ); ( 1996 ) Romieu et al. (1997 ); ( 1996 ) found larger increases in 

### 23 symptoms in assoc iation with increases in 1

- h max O 3 at lag 0, than at lag 1 or 2. Recent 

### 24 studies expanded on earlier evidence by indicating associations with multiday averages of 

### 25
O 3 concentrations. Romieu et al. (2006 ) and Escamilla

- Nuñez et al. (2008 ) found that 

### 26
ORs for associations of ambient 1

- h max O 3 concentrations with respiratory symptoms 

### 27 and medication use increased as the number of averaging days increased (up to lag 0

- 5 

### 28 avg). 

### 29

Studies of children with asthma examined factors that may modify symptom responses to 

### 30
ambient O 3 exposure but did not produce conclusive evidence. Larger O 3 - associated 

### 31 (8

- h avg [10 a.m.

- 6 p.m.] or 8

- h max) increases in symptoms were found in children 

### 32 taking asthma medication, although the specific medications examined differed between 

### 33
studies. As with results for PEF , in the NCICAS multicity cohort, O 3 - associated increases 

### 34 in morning symptoms were larger in children taking cromolyn (used to treat asthma with 

### 35 allergy) or beta

- agonists/xanthines than in children taking no medication. Odds ratios 

### 36
were similar in children taking steroids and children taking no medication ( Figure 6

- 11 

### 37

### Draft

– Do Not Cite or Quote 6

- 109 June 2012 and Table 6

- 20 ) ( Mortimer et al., 2000 ) . Among children with asthma in Southern New 

### 1 England, O 3 - associated increases in symptoms were limited mostly to children taking 

### 2 steroids, cromolyn, or leukotriene inhibitors for maintenance ( Gent et al., 2003 )

. 

### 3

In most studies of children with asthma, a majority of subjects (52 to 100%) had atopy as 

### 4 determined by sensitization to any examined allergen. While studies found O 3 - associated 

### 5 increases in pulmonary inflammation i n children with atopy (Section 6.2.3.2 ) and in 

### 6 animal models of allergy (Section 6.2.3.3 ), studies did not indicate that the risk of 

### 7
O 3 - associated respiratory symptoms differed in children with asthma with and without 

### 8 atopy. In NCICAS, Mortimer et al. (2000 ) found that an increase in 8

- h avg (10 a.m.

- 6 

### 9 p.m.) O 3 was associated with a s imilar increased incidence of asthma symptoms among 

### 10 the 79% of subjects with atopy and the 21% of subjects without atopy ( Figure 6

- 11 and 

### 11
Table 6

- 20 ). Odds ratios for O 3 did not differ by residential allergen levels. Amo ng 

### 12 children with asthma in Fresno, CA, most associations of single

- and multiday lags of 

### 13
8

- h max O 3 concentrations (0

- 14 days) with wheeze were near or below 1.0 among all 

### 14 subjects. Among the various O 3 lags examined, increases in O 3 were not consistently 

### 15 associated with increases in wheeze in subjects with cat or fungi allergy either ( Mann et 

### 16 al., 2010 )

. 

### 17

Romieu et al. (2006 ) found differences in O 3 - associated respiratory symptoms by genetic 

### 18 variants in GST enzymes, particularly, GSTP1 and less so for GSTM1. Compared with 

### 19 GSTP1 Ile/Ile or Ile/Val subjects, larger effects were estimated for GSTP1 Val/Val 

### 20 subjects ( Figure 6

- 11 and Table 6

- 20 ). The largest OR was found for difficulty breathing 

### 21 in children with asthma who had both GSTM1 null and GSTP1 Val/Val genotypes (OR: 

### 22 1.49 [95% CI: 1.14, 1.93] per 30

- ppb increase in lag 0

- 5 avg of 8

- h max O 3 ). While these 

### 23
results a re consistent with those described for antioxidant capacity modifying 

### 24
O 3 - associated changes in lung function (Section 6.2.1.2 ) and pulmonary inflammation 

### 25 [Section 6.2.3.2 for results in the same cohort ( Sienra

- Monge et al., 2004 ) ], it is important 

### 26 to note that effect modification by GSTP1 variants has not been consistent. ( Romieu et 

### 27 al., 2006 ) found an O 3 - associated decrease in FEV 1 only in children with GSTP1 Ile/Ile 

### 28 or Ile/Val genotype. Among children in southern California, GSTP1 Ile/Ile was 

### 29 associated with greater risk of asthma onset (Section 7.2.1 ). Asthma prevalence has not 

### 30 been consistently associated with a particular GSTP1 genotype either ( Tamer et al., 2004 ; 

### 31 Mapp et al., 2002 ; Hemmingsen et al., 2001 )

. 

### 32

Asthma Medication Use

Although recent studies contributed mixed evidence, the collective body of evidence 

### 33 supports associations between increases in ambient O 3 concentration and increased 

### 34 asthma medication use in children ( Figure 6

- 12 and Table 6

- 21 ). Most studies examined 

### 35

### Draft

– Do Not Cite or Quote 6

- 110 June 2012 and found associations with lags 0 or 1 of 1

- h max O 3 concentrations; however, 

### 1 associations also were found for multiday average O 3 concentrations (lag 0

- 5 avg in 

### 2 Romieu et al. (2006 ) and lags 0

- 2 avg and 0

- 4 avg in Just et al. (2002 ) . Within several 

### 3 studies, associations were consistent between respiratory symptoms and asthma 

### 4
medication use ( Escamilla

- Nuñez et al., 2008 ; Romieu et al., 2006 ; Schildcrout et al., 

### 5
2006 ; Jalaludin et al., 2004 ; Romieu et al., 1997 ; Thurston et al., 1997 ) . As an exception, 

### 6 Romieu et al. (1996 ) found that O 3 was associated with an increase in respiratory 

### 7 symptoms but not bronchodilator use, and Rabinovitch et al. (2004 ) indicated statistically 

### 8 significa nt associations with symptoms but not bronchodilator use (OR not reported). A 

### 9 few studies found higher odds of O 3 - associated increases in asthma medication use than 

### 10 in respiratory symptoms ( Just et al., 2002 ; Ostro et al., 2001 )

. 

### 11

Note: CS = corticosteroid. Results generally are presented in order of increasing mean ambient O 3 concentration. Odds ratios are from single

- pollutant models and are standardized to a 40

- ppb for 1

- h max O 3 and a 30

- ppb increase for 8

- h max or 15

- h avg O 3 . 

### Figure 6

- 12 Associations between ambient ozone concentrations and asthma medication use. Study

Schildcrout et al. (2006)

Thurston et al. (1997) Ostro et al. (2001)

Romieu et al. (1996)
Romieu et al. (1997) Romieu et al. (2006) Gielen et al. (1997) Jalaludin et al. (2004) Medication

Rescue inhaler

Beta

- agonist Extra medication

Bronchodilator

Bronchodilator Bronchodilator Bronchodilator Beta

- agonist, no steroid Corticosteroid O 3 Lag

0

0 1

0

0 0

- 5 avg

0

- 5 avg 0 1 Subgroup

Pasadena Los Angeles

GSTM1 positive GSTM1 null GSTP1 Ile/Ile Ile/Val GSTP1 Val/Val

0.5 0.7 0.9 1.1 1.3 1.5 Odds ratio (95% CI)

### Draft

– Do Not Cite or Quote 6

- 111 June 2012 Table 6

- 21 Additional characteristics and quantitative data for studies presented in Figure 6

- 12

. Study * Location/Population O 3 Averaging Time O 3 Lag Medication Subgroup Standardized OR (95% CI) a

Jalaludin et al. (2004 ) Sydney, Australia 125 children with asthma, mean age 9.6 yr 15

- h avg (6 a.m.
- 9 p.m.) 1 Beta

- agonist, no corticosteroid 1.06 (0.91, 1.23)

Inhaled corticosteroid 1.06 (0.97, 1.16)

Gielen et al. (1997 ) Amsterdam, Netherlands 61 children with asthma, ages 7

- 13 yr 8

- h max 0 Bronchodilator 1.10 (0.78, 1.55)

Schildcrout et al. (2006 ) Albuquerque, NM ; Baltimore, MD; Boston, MA; Denver, CO; San Diego, CA; Seattle, WA; St. Louis, MO; Toronto, ON, Canada 990 children with asthma, ages 5

- 12 yr 1

- h max 0 Rescue inhaler 1.01 (0.89, 1.15)

Ostro et al. (2001 ) Los Angeles, CA 138 children with moderate/severe asthma, ages 6

- 13 yr 1

- h max 1 Any extra medication Pasadena Los Angeles 1.15 (1.12, 1.19) 1.10 (1.03, 1.19)

Thurston et al. (1997 ) CT River Valley, CT 166 c hildren with asthma, ages 7

- 13 yr 1

- h max 0 Beta

- agonist 1.17 (0.96, 1.44)

Romieu et al. (2006 ) Mexico City, Mexico 151 children with asthma, mean age 9 yr 1

- h max 0

- 5 avg Bronchodilator GSTM1 positive 1.04 (0.96, 1.13)

GSTM1 null 1.00 (0.92, 1.09)

GSTP1 Ile/Ile
or Ile/Val 0.96 (0.90, 1.02)

GSTP1 Val/Val 1.10 (1.02, 1.19)

Romieu et al. (1996 ) northern Mexico City, Mexico 71 children with asthma, ages 5

- 7 yr 1

- h max 0 Bronchodilator 0.97 (0.93, 1.01)

Romieu et al. (1997 ) southern Mexico City, Mexico 65 children with asthma, ages 5

- 13 yr 1

- h max 0 Bronchodilator 1.02 (1.00, 1.05)

### Draft

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- 112 June 2012 Study * Location/Population O 3 Averaging Time O 3 Lag Medication Subgroup Standardized OR (95% CI) a

Just et al. (2002 ) b Paris, France 82 Children with asthma, mean (SD) age 10.9 (2.5) yr 24

- h avg 0 Beta

- agonist, no steroid 3.95 (1.22, 12.9)

Gent et al. (2003 ) b CT, southern MA 130 children with asthma on maintenance medication 1

- h max 0 Bronchodilator O 3 <43.2 ppb 1.00 (reference)

O 3 43.2

- 51.5 ppb 1.00 (0.96, 1.05)

O 3 51.6

- 58.8 ppb 1.04 (1.00, 1.09)

O 3 58.9

- 72.6 ppb 1.02 (0.98, 1.07)

O 3 ≥ 72.7 ppb 1.05 (0.97, 1.13)

*Includes studies in Figure 6

- 12 , plus others.

a Effect estimates are standardized to a 40

- ppb increase for 1

- h max O 3 , a 30

- ppb increase for 8

- h max or 15

- h avg O 3 , and a 20

- ppb increase for 24

- h avg O 3 . b Results not include d in Figure 6

- 12 . Results from Just et al. (2002 ) were out of range of other estimates, and results from Gent et al. (2003 ) were pr esented per quintile of ambient O 3 concentration.

Changes in Activity

While investigation has been limited, evidence does not consistently demonstrate O 3 - 

### 1 associated diminished activity in children with asthma ( O'Connor et al., 2008 ; Delfino et 

### 2 al., 2003 ) . These studies examined different O 3 averaging times and lags. In the multicity 

### 3 ICAS cohort, O'Connor et al. (2008 ) found that a 20

- ppb increase in lag 1

- 19 avg of 

### 4
24

- hour O 3 was associated with a 10% lower odds (95% CI:

- 26, 10) of slow play. In a 

### 5 small (n = 22) panel study conducted in children with asthma in Los Angeles CA, 

### 6 Delfino et al. (2003 ) found that a 40

- ppb increase in lag 0 of 1

- h max O 3 was associated 

### 7 with an increase in symptoms that interfered with daily activity with an OR of 7.41 

### 8 (95% CI : 1.18, 43.2). Several studies reported increases in school absenteeism in children 

### 9
with asthma in association with increases in ambient O 3 concentration with long lag 

### 10 periods (14

- day and 30

- day distributed lags, 19

- day avg) ( O'Connor et al., 2008 ; Gilliland 

### 11 et al., 2001 ; Chen et al., 2000 ) . Whereas Chen et al. (2000 ) and O'Connor et al. (2008 ) 

### 12 examined absences for any reason, Gilliland et al. (2001 ) found associations with 

### 13 absences for respiratory illnesses. Despite this evidence, several limitations are notable, 

### 14
includ ing the lack of a well

- characterized mode of action for long lag periods of O 3 

### 15 exposure and the potential for residual seasonal confounding with examination of long 

### 16 lag periods. In analyses of single

- day lags, Gilliland et al. (2001 ) found associations with 

### 17
O 3 lagged 1 to 5 days, indicating respiratory absences may be affected by O 3 exposures 

### 18
with shorter la g periods. 

### 19

### Draft

– Do Not Cite or Quote 6

- 113 June 2012 6.2.4.2 Adults with Respiratory Disease

Within a small body of studies, several found that increases in ambient O 3 concentration 

### 1 (8

- hour or 1

- h max) were associated with increases in respiratory symptoms in adults 

### 2
with asthma ( Khatri et al., 2009 ; Feo Brito et al., 2007 ; Ross et al., 2002 ) . Details from 

### 3 studies of respiratory symptoms in adults with respiratory disease regarding location, 

### 4 time period, and ambient O 3 concentrations are presented in Table 6

- 22 . These studies 

### 5 used different exposure assessment methods: concentrations averaged from sites closest 

### 6 to subjects’ location each hour ( Khatri et al., 2009 ) or concentrations measured at one 

### 7 ( Ross et al., 2002 ) or multiple ( Feo Brito et al., 2007 ) city sites. Park et al. (2005a ) found 

### 8
inconsistent associations for 24

- h avg O 3 measured at 10 city sites among the various 

### 9 symptoms and medication use examined in adults with asthma in Korea during a period 

### 10 of dust storms. In a study of adults with COPD in London, England, increases in lag 1 of 

### 11
8

- h max O 3 (at a single city site) wer e associated with higher odds of dyspnea and sputum 

### 12 changes but lower odds of nasal discharge, wheeze, or upper respiratory symptoms 

### 13 ( Peacock et al., 2011 )

. 

### 14

### Draft

– Do Not Cite or Quote 6

- 114 June 2012 Table 6

- 22 Mean and upper percentile ozone concentrations in epidemiologic studies of respiratory symptoms and medication use in adults with respiratory disease

. Study * Location Study Period O 3 Averaging Time Mean/Median Concentration (ppb) Upper Percentile Concentrations (ppb)

Khatri et al. (2009 ) Atlanta, GA May

- September 2003, 2005, 2006 8

- h max 61 a 75th: 74 a

Feo Brito et al. (2007 ) Ciudad Real and Puertollano, Spain May

- June 2000

- 2001 1

- h max 65.9 (Ciudad Real) b 56.8 (Puertollano) b Max: 101.5 b (Ciudad Real); 138.2 b (Puertollano)

Ei swerth et al. (2005 ) Glendora, CA October

- November 1983 1

- h max NR NR

Ross et al. (2002 ) East Moline, IL April

- October 1994 8

- h avg 41.5 Max: 78.3

Peacock et al. (2011 ) London, England All

- year 1995

- 1997 8

- h max 15.5 Autumn/Winter Max: 32 Spring/Summer Max: 74 Park et al. (2005a ) Incheon, Korea March

- June 2002 24

- h avg Dust event days: 23.6 Control days: 25.1 NR

Wiwatanadate and Liwsrisakun (2011 ) Chiang Mai, Thai land August 2005

- June 2006 24

- h avg 17.5 90th: 26.82, Max: 34.65

* Note: Studies presented in order of first appearance in the text of this section. NR = Not Reported

a Individual

- level estimates were derived based on time spent in the vicinity of various O 3 monitors.

b Concentrations converted from μg/m 3 to ppb using the conversion factor of 0.51 assuming standard temperature (25°C) and pressure (1 atm).

Some studies that included adults with asthma examined populations with a high 

### 1 prevalence of atopy. In a study of children and adults with asthma (at least 53% with 

### 2 atopy), Ross et al. (2002 ) found that an increase in lag 1

- 3 avg of 8

- h max O 3 was 

### 3 associated with an increase in symptom score and asthma medication use. Feo Brito et al. 

### 4 (2007 ) followed 137 adults with asthma in two central Spain cities. A ll subjects had 

### 5 pollen allergy and were examined during pollen season. In Puertollano, O 3 concentrations 

### 6 were obtained from four city monitors, and a 40

- ppb increase in lag 3 of 1

- h max O 3 was 

### 7 associated with a 14.3% increase (95% CI: 3.6, 26.0) in the num ber of subjects reporting 

### 8 respiratory symptoms, adjusting only for time trend. The association was much weaker in 

### 9 Ciudad Real (2.3% increase [95% CI:

- 14, 21%] per 40

- ppb increase in lag 4 of 1

- h max 

### 10
O 3 ), a city characterized by lower ambient air pollution levels and a narrower range of 

### 11
ambient O 3 concentrations as measured at a single site established by investigators. 

### 12

Cross

- sectional studies reported ambient O 3 - associated decreases in activity in adults 

### 13 with asthma; however, due to various limitations in the collective body of evidence, firm 

### 14 conclusions are not warranted. Although conducted over single seasons, studies did not 

### 15 consider confounding by meteorological factors. In a warm season study in Atlanta, GA 

### 16 (described in Section 6.2.1.2 ), Khatri et al. (2009 ) found that a 30

- ppb increase in lag 2 of 

### 17

### Draft

– Do Not Cite or Quote 6

- 115 June 2012 8

- h max O 3 was associated with a 0.69

- point decrease (95% CI:

- 1.28,

- 0.11) in the 

### 1 Juniper quality of life sco re, which incorporates indices for symptoms, mood, and activity 

### 2 limitations (7

- point scale). In a fall study conducted in the Los Angeles, CA area in 

### 3 individuals with asthma (age 16 years and older), Eiswerth et al. (2005 ) found that a 

### 4
40

- ppb increase in 1

- h max O 3 was associated with a 0.24% (95% CI: 0.08, 0.40%) lower 

### 5 probabili ty of indoor activity but higher probability of outdoor activity. The authors 

### 6 acknowledged that their findings were unexpected and may have been influenced by lack 

### 7 of control for potential confounders but interpreted the decrease in indoor activities as 

### 8

re st replacing chores. In contrast with the aforementioned studies, a panel study of 

### 9 individuals with asthma (ages 13

- 78 years) in Thailand found that a 20

- ppb increase in 

### 10 lag 4 of 24

- h avg O 3 was associated with a 26% (95% CI: 4, 43) lower odds of symptoms 

### 11
that interfered with activities ( Wiwatanadate and Liwsrisakun, 2011 )

. 

### 12

6.2.4.3 Populations not Restricted to Individuals with Asthma

Locations, time periods, and ambient O 3 concentrations for stu dies of symptoms in 

### 13 populations not restricted to individuals with asthma are presented in Table 6

- 23 . Most 

### 14 studies examined children, and in contrast with lung function results (Section 6.2.1.2 ), 

### 15
short

- term increases in ambient O 3 concentration were not consistently associated with 

### 16
increases in r espiratory symptoms in children in the general population ( Figure 6

- 13 and 

### 17
Table 6

- 24 ). Because examination of adults was limited, conclusions cannot be drawn. 

### 18

### Draft

– Do Not Cite or Quote 6

- 116 June 2012 Table 6

- 23 Mean and upper percentile ozone concentrations in epidemiologic studies of respiratory symptoms in populations not restri cted to individuals with asthma

. Study * Location Study Period O 3 Averaging Time Mean/Median Concentration (ppb) Upper Percentile Concentrations (ppb)

Neas et al. (1995 ) Uniontown, PA June

- August 1990 12

- h avg (8 a.m.

- 8 p.m.) 37.2 Max: 87.5

Linn et al. (1996 ) Rubidoux, Upland, Torrence, CA September

- June 1992

- 1994 24

- h avg personal
24

- h avg ambient 5 23 Max: 16 Max: 53

Hoek and Brunekreef (1995 ) Deurne and Enkhuizen, Netherlands March

- July 1989 1

- h max Deurne: 57 Enkhuizen: 59 Max: 107 Max: 114

Rodriguez et al. (2007 ) Perth, Australia All

- year, 1996

- 20 03 24

- h avg 1

- h max 28 33 Max: 74 Max: 95

Moon et al. (2009 ) 4 cities, South Korea April

- May 2003 8

- h avg (10 a.m.

- 6 p.m.) NR NR

Ward et al. (2002 ) Birmingham and Sandwell, England January

- March, May

- July 1997 24

- h avg Winter median: 13.0 Summer median: 22.0 Winter Max: 33 Summer Max: 41

Triche et al. (2006 ) Southwestern VA June

- August 1995

- 1996 24

- h avg 8

- h max 1

- h max 35.2 54.5 60.8 75th: 40.6, Max: 56.6 75th: 6 4.1, Max: 87.6 75th: 70.0, Max: 95.0

Gold et al. (1999 ) Mexico City, Mexico January

November 1991 24

- h avg 52.0 a Max: 103 a

Apte et al. (2008 ) Multiple U.S. cities (NR) Winter or summer 1994

- 1998 Workday avg (8 a.m.
- 5 p.m.) 34.2 b Max: 86.2 b

24

- h avg 25.5 b Max: 67.3 b

* Note: Studies presented in order of first appearance in the text of this section. NR = Not Reported.

a Measured at subject’s schools.

b Concentrations converted from μg/m 3 to ppb using the conversion factor of 0.51 assuming standard temperature (25°C) and pressure (1 atm).

Children

Although evidence of O 3 - associated increases in respiratory symptoms in children was 

### 1 inconsistent, it did not appear to be attributable to the differences in exposure assessment 

### 2 method among studies [e.g., O 3 measured at a single site ( Linn et al., 1996 ; Hoek and 

### 3 Brunekreef, 1995 ) , O 3 averaged across multiple city sites ( Rodriguez et al., 2007 ) , O 3 

### 4
measured at sites near schools ( Moon et al., 2009 ; Ward et al., 2002 ) ]. Some studies that 

### 5
found weak or inconsistent associations between ambient O 3 concentrati ons and 

### 6 respiratory symptoms found O 3 - associated decrements in lung function ( Ward et al., 

### 7
2002 ; Linn et al., 1996 ) . In their study of healthy children in Uniontown, PA, Neas et al. 

### 8 (1995 ) found differences in association with respiratory symptoms between two estimates 

### 9
of O 3 exposure. Ambient O 3 concentrations were measured at one central site in town. 

### 10

### Draft

– Do Not Cite or Quote 6

- 117 June 2012 Subjects spent a mean 5.4 hours outdoors during the 12

- hour period (8 a.m.

- 8 p.m.) over 

### 1
which O 3 concentrations were averaged and symptoms were reported. Evening cough 

### 2 was more strongly associated with O 3 concentrations weighted by time spent outdoors 

### 3 (OR: 2.20 [95% CI: 1.02, 4.75] per 30

- ppb increase in lag 0 of 12

- h avg O 3 ) than with 

### 4 unweighted O 3 concentrations (OR: 1.36 [95% CI: 0.86, 2.13]). Time spent outdoo rs has 

### 5
been shown to influence O 3 personal

- ambient ratios and correlations (Section 4.3.3 ), thus 

### 6 the weighted O 3 concentrations may have represente d personal O 3 exposures better. 

### 7

Note: Results generally are presented in increasing order of mean ambient O 3 concentration. URS = Upper respiratory symptoms. Odds ratios are from single

- pollutant models and are standardized to a 40

- , 30

- , and 20

- ppb increase for 1

- h max, 8

- h max (or 12

- h avg), and 24

- h avg O 3 concentrations, respectively.


### Figure 6

- 13 Associations between ambient ozone concentrations and respiratory symptoms in children in the general population. Study Ward et al. (2002)

Hoek and Brunekreef (1995)
Moon et al. (2009)

Neas et al. (1995)
Triche et al. (2006)

Gold et al. (1999) Symptom Wheeze, summer Cough, summer
Cough Any symptom

URS

Evening cough

Wheeze

Phlegm Lag
0

0

0

0
0, 24

- h avg 0, 8

- h max 0, 1

- h max

0 Subgroup

All subjects Jeju Island

►

► ► ►

0 1 2 3 Odds ratio (95% CI)

### Draft

– Do Not Cite or Quote 6

- 118 June 2012 Table 6

- 24 Additional characteristics and quantitative data for studies represented in Figure 6

- 13.

Study * Location/ Population O 3 Lag O 3 Averaging Time Symptom Subgroup Standardized OR (95% CI) a

Ward et al. (2002 ) Birmingham and Sandwell, England 162 children, age 9 yr 0

- 6 avg 24

- h avg Wheeze, summer Cough, summer 0.69 (0.51, 0.94) 0.98 (0.80, 1.21)

Hoek and Brunekreef (1995 ) Enkhuizen, Netherlands 300 children, ages 7

- 11 yr 0 1

- h max Cough Any symptom 0.86 (0.61, 1.22) 0.94 (0.76, 1.16)

Moon et al. (2009 ) 4 cities, South Korea 696 children, ages <13 yr 0 8

- h avg (10 a.m.
- 6 p.m.) URS All subjects Jeju Island 0.96 (0.90, 1.03) 1.11 (0.95, 1.30)

Neas et al. (1995 ) Uniontown, PA 83 healthy children, 4th and 5th grades 0 12

- h avg (8 a.m.

- 8 p.m.) Evening cough 2.20 (1.02, 4.75) b

Triche et al. (2006 ) Southwestern VA 691 infants of mothers with asthma, age <1 yr 0 24

- h avg 8

- h max 1

- h max Wheeze 2.34 (1.02, 5.37) 1.48 (0.49, 4.41) 1.73 (0.48, 6.22)

Gold et al. (1999 ) Mexico City, Mexico 40 children, ages 8

- 11 yr 1 24

- h avg Phlegm 1.02 (1.00, 1.04)

Linn et al. (1996 ) c Rubidoux, Upland, Torrence, CA 269 children, 4th and 5th grades 0 24

- h avg Evening symptom
score - 0.96 (

- 2.2, 0.26)

*Includes studies in Figure 6

- 13 , plus others. URS = Upper respiratory symptoms

a Effect estimates are standardized to a 40

- , 30

- , and 20

- ppb increase for 1

- h max, 8

- h max (or 8

- h avg or 12

- h avg), and 24

- h avg O 3 , respective ly.

b O 3 concentrations were weighted by the proportion of time spent outdoors.

c Results not presented in Figure 6

- 13 because outcome is a continuous v ariable indicating intensity of symptoms (negative indicates improvement in symptoms).

Several other panel studies of children, in which asthma prevalence ranged from 0 to 

### 1 50%, reported null or negative associations between various averaging times and lag s of 

### 2
ambient O 3 concentration and respiratory symptoms ( Moon et al., 2009 ; Rodriguez et al., 

### 3
2007 ; Ward et al., 2002 ; Linn et al., 1996 ; Hoek and Brunekreef, 1995 ) ( Figure 6

- 13 and 

### 4
Table 6

- 24 ). Among children in Mexico City, Gold et al. (1999 ) reported an increase in 

### 5 phlegm in association with an increase in lag 1 of 24

- h avg O 3 concentration measured at 

### 6 schools; however, investigat ors acknowledged being unable to distinguish between the 

### 7
effects of O 3 and PM 10 due to their high correlation (r = 0.75). 

### 8

Unlike other studies that examined ambient O 3 concentrations from a single monitoring 

### 9 site, Triche et al. (2006 ) found respiratory symptoms to be associated with O 3 measured 

### 10

### Draft

– Do Not Cite or Quote 6

- 119 June 2012 at a site that for some subjects was located >100 miles away from home ( Fig ure 6

- 13 and 

### 1
Table 6

- 24 ). Subjects included infants in Southwestern VA. Odds ratios wer e 46

- 73% 

### 2 larger in the group who had mothers with asthma than among all infants ( Triche et al., 

### 3
2006 ) . Larger ORs were found for 24

- h avg than 1

- hour or 8

- h max O 3 concentrations, 

### 4 particu larly for wheeze but less so for difficulty breathing. While these results suggested 

### 5 that children with mothers with asthma may be at increased risk of O 3 - related respiratory 

### 6 morbidity, the authors acknowledged that mothers with asthma may be more likely t o 

### 7 report symptoms in their children. Additionally, transient wheeze, which is common in 

### 8 infants, may not predict respiratory morbidity later in life. In another cohort of children 

### 9 with parental history of asthma that was followed to an older age (5 years), increases in 

### 10
ambient O 3 concentration (increment of effect estimate not reported) were not associated 

### 11 with increases in respiratory symptoms ( Rodriguez et al., 2007 )

. 

### 12

Adults

A cross

- sectional study of 4,200 adult workers from 100 office buildings across the U.S. 

### 13
f ound that multiple ambient O 3 metrics, including the 24

- h, workday (8 a.m.

- 5 p.m.), and 

### 14 late workday (3

- 6 p.m.) average, were associated with similar magnitudes of increase in 

### 15 building

- related symptoms ( Apte et al., 2008 )

. It should be noted that office workers 

### 16 likely have a low personal

- ambient O 3 correlation and ratio, thus the implications of these 

### 17 findings compared to those of the other respiratory symptom studies are limited. 

### 18

6.2.4.4 Confounding in Epidemiologic Studies of Respiratory Symptoms and Medication Use

Epidemiologic evidence does not indicate that confounding by meteorological factors or 

### 19 copollutant exposures fully accounts for associations observed between short

- term 

### 20
increases in ambient O 3 concentratio n and respiratory symptoms and medication use. 

### 21 Except where specified in the text, studies found O 3 - associated increases in respiratory 

### 22 symptoms or medication in statistical models that adjusted for temperature. Thurston et 

### 23 al. (1997 ) found no independent association between temperature and respiratory 

### 24 symptoms among children with asthma at summer camps. A few studies additionally 

### 25 included humidity in models ( Triche et al., 2006 ; Ros s et al., 2002 )

. 

### 26

Several studies that examined populations with a high prevalence of atopy found 

### 27
O 3 - associated increases in respiratory symptoms and asthma medication use with 

### 28 adjustment for daily pollen counts ( Just et al., 2002 ; Ross et al., 2002 ; Gielen et al., 

### 29
1997 )

. Gielen et al. (1997 ) and Ross et al. (2002 ) examined populations with a high 

### 30 prevalence of grass pollen allergy (52% and 38%, respectively). In a study conducted 

### 31

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- 120 June 2012 over multiple seasons, Ross et al. (2002 ) found a similar magnitude of asso ciation 

### 1
between O 3 and morning symptoms and medication use with adjustment for pollen 

### 2

counts. Feo Brito et al. (2007 ) followed adults in central Spain specifically with asthma 

### 3 and pollen allergy. In one city, O 3 was associated with an increase in the number of 

### 4 subjects rep orting symptoms. A smaller increase was estimated for pollen. Conversely, in 

### 5 another city, pollen was associated with an increased reporting of respiratory symptoms, 

### 6
whereas O 3 was not. The results suggested that O 3 and pollen may have independent 

### 7
effects that vary by location, depending on the mix of ambient pollutants. 

### 8

Results from copollutant models did not indicate strong confounding by copollutants 

### 9
such as PM 2.5 , PM 10 , sulfate, SO 2 , or NO 2 ( Table 6

- 25 ). Notably, studies examined 

### 10 different averaging times for O 3 (1

- h max or 8

- h avg) and copollutants (3

- hour to 

### 11
24

- h avg) and reported a range of correlations between O 3 and copollutants, which may 

### 12 complicate interpretation of copollutant model results. Information on potential 

### 13 copollutant confounding of asthma medication use results was limited. The association 

### 14
between O 3 and bronchodilator use did not change with adjust ment for PM 2.5 in Gent et 

### 15 al. (2003 ) but decreased in magnitude with adjustment for 12

- h avg sulfate in Thurston et 

### 16 al. (1997 ) . In Thurston et al. (1997 ) and Gent et al. (2003 ) , 1

- h max O 3 was highly 

### 17
correlated with 12

- h avg sulfate (r = 0.74) and 24

- h avg PM 2.5 (r = 0.77), respectively, 

### 18 making it difficult to distinguish the independent effects of O 3 . Studies conducted 

### 19 concurrently in two areas of Mexico City examined 1

- h max O 3 and 24

- h avg PM 10 or 

### 20
PM 2.5 and found robust ORs for respiratory symptoms for both O 3 and PM ( Romieu et al., 

### 21
1997 ; Romieu e t al., 1996 )

. Romieu et al. (1997 ) reported a moderate correlation between 

### 22
1

- h max O 3 and 24

- h avg PM 10 (r = 0.47). Associati ons between O 3 and respiratory 

### 23 symptoms were observed in NCICAS in copollutant models with SO 2 , NO 2 , or PM 10 , 

### 24 which were examined with different averaging times and lags than was O 3 ( Mortimer et 

### 25 al., 2002 ) ( Table 6

- 25 ). Also difficult are interpreta tions of the O 3 - associated increases in 

### 26 respiratory symptoms found with adjustment for two copollutants in the same model 

### 27 (i.e., PM 2.5 plus NO 2 or PM 10

- 2.5 ) ( Escamilla

- Nuñez et al., 2008 ; Triche et al., 2006 )

. 

### 28

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– Do Not Cite or Quote 6

- 121 June 2012 Table 6

- 25 Associations between ambient ozone concentrations and respiratory symptoms in single

- and co

- pollutant models.

Study Location/Population O 3 Metrics Symptom OR for O 3 in Single

- Pollutan t Model (95% CI) a OR for O 3 in Copollutant Model (95% CI) a

Mortimer et al. (20 02 ) Bronx, East Harlem, NY; Baltimore, MD; Washington, DC; Detroit, MI, Cleveland, OH; Chicago, IL; St. Louis, MO 846 children with asthma, ages 4

- 9 yr 8

- h avg (10 a.m.
- 6 p.m.) Lag 1

- 4 avg Morning symptoms 8 cities with SO 2 data 1.35 (1.04, 1.74) With lag 1

- 2 avg, 3

- h avg SO 2 1.23 (0.94, 1.61)

7 cites with NO 2 data 1.25 (0.94, 1.67) With lag 1

- 6 avg, 24

- h avg NO 2 1.14 (0.85, 1.55)

3 cities with PM 10 data 1.21 (0.61, 2.41) With lag 1

- 2 avg, 24

- h avg PM 10 1.08 (0.49, 2.39)

Thurston et al. (1997 ) CT River Valley 166 children with asthma, ages 7

- 13 yr 1

- h max Chest symptoms 1.21 (1.12, 1.31) b With lag 0, 12

- h avg sulfate 1.19 (1.06, 1.35) b
Lag 0 Beta

- agonist use 1.20 (1.09, 1.32) b With lag 0, 12

- h avg sulfate 1.07 (0.92, 1.24) b

Romieu et al. (1996 ) Mexico City, Mexico 71 children with asthma, ages 5

- 7 yr 1

- h max Lag 0 Lower respiratory symptoms 1.07 (1.02, 1.12) With l ag 0, 24

- h avg PM 2.5 1.06 (1.02, 1.10)

Romieu et al. (1997 ) Mexico City, Mexico 65 children with asthma, ages 5

- 13 yr 1

- h max Lag 0 Lower respiratory symptoms 1.09 (1.04, 1.14) With lag 0, 24

- h avg PM 10 1.09 (1.01, 1.19)

Results generally are presented in order of increasing mean ambient O 3 concentration.

a ORs are standardized to a 40

- and 30

- ppb increase for 1

- h max and 8

- h avg O 3 , respectively.

b Temperature not included in models.



### 6.2.4.5 Summary of Epidemiologic Studies of Respiratory Symptoms and Asthma Medication Use

Comprising a majority of available evidence, single

- city and

- region epidemiologic 

### 1 studies provide consistent evidence for the effects of short

- term increases in ambient O 3 

### 2 exposure on increasing respiratory symptoms and asthma medication use in childr en with 

### 3 asthma ( Figure 6

- 11 and Figure 6

- 12 a nd Table 6

- 20 and Table 6

- 21 ). Evidence from t he 

### 4 few available U.S. multicity studies is less consistent ( O'Connor et al., 2008 ; Schildcrout 

### 5 et al., 2006 ; Mortimer et al., 2002 ) . Findings from a small body of studies indicate 

### 6
O 3 - associated increases in respiratory symptoms in adults with asthma. Associations 

### 7
between short

- term increases in ambient O 3 concentration and reduced activity in 

### 8
children or adults with asthma are not clearly demonstrated. While O 3 - associated 

### 9 increases in school absenteeism were found in children with asthma, evidence for 

### 10 respiratory

- related absences and for O 3 exposure lag periods shorter than 14 days is 

### 11 sparse. Short

- term increases in ambient O 3 concentration were not consistently associated 

### 12

### Draft

– Do Not Cite or Quote 6

- 122 June 2012 with increases in respiratory symptoms in groups comprising children with and without 

### 1
asthma. 

### 2

Increases in respiratory symptoms and medication use were associated with increases in 

### 3
ambient O 3 concentration assigned to subjects using various methods. Associations were 

### 4 found with methods likely to represent better ambient exposures, including O 3 measured 

### 5 on site and at the time of children’s outdoor activity ( Thurston et al., 1997 ) and 

### 6 concentrations weighted by time spent outdoors ( Neas et al., 1995 ) . However, 

### 7
associations also were found wi th methods that varied in their representation of ambient 

### 8 exposures and spatial variability in ambient concentrations, i.e., concentrations averaged 

### 9 among subjects’ locations each hour ( Khatri et al., 2009 ) , measured within 5 km of 

### 10
schools or homes ( Escamilla

- Nuñez et al., 2008 ; Romieu et al., 2006 ; 1997 ; 1996 )
, 

### 11 averaged across multiple sites ( Feo Brito et al., 2007 ; Gent et al., 2003 ; M ortimer et al., 

### 12
2002 ) , and measured at a single site ( Ross et al., 2002 ; Gielen et al., 1997 )

. 

### 13

Associations with respiratory symptom s were demonstrated most frequently for 1

- h max 

### 14
and 8

- h max or avg O 3 , and within

- study comparisons indicated similar ORs for 1

- h max 

### 15
and 8

- h max O 3 ( Delfino et al., 2003 ; Gent et al., 2003 ) . Respiratory symptoms also were 

### 16
associated with 12

- hour and 24

- h avg O 3 ( Jalaludin et al., 2004 ; Gold et al., 1999 ; Neas et 

### 17 al., 1995 ) . Epidemiologic studies examined respiratory symp toms associated with O 3 

### 18 concentrations lagged 0 to 5 days and those averaged over 2 to 19 days. While O 3 at lags 

### 19 0 or 1 were consistently associated with respiratory symptoms, several studies found 

### 20 larger ORs for multiday averages (3

- to 6

- day) of O 3 ( Escamilla

- Nuñez et al., 2008 ; 

### 21 Romieu et al., 2006 ; Just et al., 2002 ; Mortimer et al., 2002 ; Ross et al., 2002 )

. 

### 22 Epidemiologic findings for lagged or multiday average O 3 are supported by evidence that 

### 23
O 3 sensitizes bronchial smooth muscle to hyperreactivity and thus acts as a primer for 

### 24 subsequent exposure to antigens such as allergens (Section 5.3.5 ). Many studies 

### 25 examined populations with asthma with a high p revalence of atopy (52

- 100%). In these 

### 26 populations, sensitization of airways provides a biologically plausible mode of action by 

### 27 which increases in respiratory symptoms result from increases in O 3 exposure after a lag 

### 28
or accumulated over several days. Furt her support is provided by findings that airway 

### 29 hyperresponsiveness (Section 6.2.2.1 ) and some indicators of inflammation 

### 30 (Section 6.2.3.1 ) remained elevated following repeated O 3 exposures in controlled human 

### 31 exposure studies and by observations from epidemiologic studies that increases in 

### 32 pulmonary inflammation were associated with multiday average O 3 concentrations 

### 33 (Section 6.2.3.2 ). 

### 34

There is not strong evidence that O 3 - associated increases in respiratory symptoms are 

### 35 confounded by temperature, pollen, or copollutants. In limited analysis, ambient O 3 was 

### 36
associated with res piratory symptoms with adjustment for copollutants, primarily PM. 

### 37

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– Do Not Cite or Quote 6

- 123 June 2012 However, identifying the independent effects of O 3 in some studies was complicated due 

### 1 to the high correlations observed between O 3 and PM or different lags and averaging 

### 2
times examined for copollutants. Nonetheless, the consistency of associations among 

### 3 individuals with asthma with and without adjustment for ambient copollutant 

### 4 concentrations combined with findings from controlled human exposure studies for the 

### 5
direct effect of O 3 exposure p rovide substantial evidence for the independent effects of 

### 6
short

- term ambient O 3 exposure on increasing respiratory symptoms. 

### 7

6.2.5 Lung Host Defenses

The mammalian respiratory tract has a number of closely integrated defense mechanisms 

### 8 that, when functioning no rmally, provide protection from the potential health effects 

### 9 attributed to exposure to a wide variety of inhaled particles and microbes. For simplicity, 

### 10 these interrelated defenses can be divided into two major parts: (1) nonspecific (transport, 

### 11 phagocytos is, and bactericidal activity) and (2) specific (immunologic) defense 

### 12 mechanisms. A variety of sensitive and reliable methods have been used to assess the 

### 13
effects of O 3 on these components of the lung’s defense system to provide a better 

### 14 understanding of t he health effects associated with the inhalation of this pollutant. The 

### 15 previous O 3 AQCD stated that animal toxicological studies provide extensive evidence 

### 16
that acute O 3 exposures as low as 0.08 to 0.5 ppm can cause increases in susceptibility to 

### 17
infectio us diseases due to modulation of lung host defenses. Table 6

- 6 through Table 6

- 9 

### 18 ( U.S. EPA, 1996g
, h
, i
, j ) beginning on page 6

- 41 of the 1996 O 3 AQCD ( U.S. EPA, 

### 19
1996a ) , and Table AX5

- 7 ( U.S. EPA, 2006c ) , beginning on page AX5

- 8 of the 2006 O 3 

### 20 AQCD ( U.S. EPA, 2006b ) , present studies on the effects of O 3 on host defense 

### 21
mechanisms. This section discusses the v arious components of host defenses, such as the 

### 22 mucociliary escalator, the phagocytic, bactericidal, and regulatory role of the alveolar 

### 23 macrophages (AMs), the adaptive immune system, and integrated mechanisms that are 

### 24 studied by investigating the host’s r esponse to experimental pulmonary infections. 

### 25

6.2.5.1 Mucociliary Clearance

The mucociliary system is one of the lung’s primary defense mechanisms. It protects the 

### 26 conducting airways by trapping and quickly removing material that has been deposited or 

### 27 is being cl eared from the alveolar region by migrating alveolar macrophages. Ciliary 

### 28 movement directs particles trapped on the overlying mucous layer toward the pharynx, 

### 29 where the mucus is swallowed or expectorated. 

### 30

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– Do Not Cite or Quote 6

- 124 June 2012 The effectiveness of mucociliary clearance can be determined by measuring such 

### 1 biological activities as the rate of transport of deposited particles; the frequency of ciliary 

### 2 beating; structural integrity of the ciliated cells; and the size, number, and distribution of 

### 3

mucus

- secreting cells. Once this def ense mechanism has been altered, a buildup of both 

### 4 viable and nonviable inhaled substances can occur on the epithelium and may jeopardize 

### 5 the health of the host, depending on the nature of the uncleared substance. Impaired 

### 6 mucociliary clearance can result in an unwanted accumulation of cellular secretions, 

### 7 increased infections, chronic bronchitis, and complications associated with COPD. A 

### 8 number of previous studies with various animal species have examined the effect of O 3 

### 9 exposure on mucociliary clearance and reported morphological damage to the cells of the 

### 10
tracheobronchial tree from acute and sub

- chronic exposure to O 3 0.2 ppm and higher. The 

### 11 cilia were either completely absent or had become noticeably shorter or blunt. After 

### 12 placing these animals in a cl ean

- air environment, the structurally damaged cilia 

### 13 regenerated and appeared normal ( U.S. EPA, 1986 ) . Based on such morphological 

### 14 observations, related effects such as ciliostasis, increased mucus secretions, and a slowing 

### 15 of mucociliary transport rates might be expected. However, no measurable changes in 

### 16
ci liary beating activity have been reported due to O 3 exposure alone. Essentially no data 

### 17 are available on the effects of prolonged exposure to O 3 on ciliary functional activity or 

### 18 on mucociliary transport rates measured in the intact animal. In general, fun ctional 

### 19 studies of mucociliary transport have observed a delay in particle clearance soon after 

### 20 acute exposure. Decreased clearance is more evident at higher doses (1 ppm), and there is 

### 21
some evidence of attenuation of these effects ( U.S. EPA, 1986 ) . However, no recent 

### 22
studies have evaluated the effects of O 3 on mucociliary clearance. 

### 23

6.2.5.2 Alveolobronchiolar Transport Mechanism

In addition to the transport of particles deposited on the mucous surface layer of the 

### 24 conducting airways, particles deposited in the deep lung may be removed either up the 

### 25 respiratory trac t or through interstitial pathways to the lymphatic system. The pivotal 

### 26 mechanism of alveolobronchiolar transport involves the movement of AMs with 

### 27 phagocytized particles to the bottom of the mucociliary escalator. Failure of the AMs to 

### 28 phagocytize and seq uester the deposited particles from the vulnerable respiratory 

### 29 membrane can lead to particle entry into the interstitial spaces. Once lodged in the 

### 30 interstitium, particle removal is more difficult and, depending on the toxic or infectious 

### 31 nature of the par ticle, its interstitial location may allow the particle to set up a focus for 

### 32 pathologic processes. Although some studies show reduced early (tracheobronchial) 

### 33
clearance after O 3 exposure, late (alveolar) clearance of deposited material is accelerated, 

### 34

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– Do Not Cite or Quote 6

- 125 June 2012 pre sumably due to macrophage influx (which in itself can be damaging due to proteases 

### 1 and oxidative reactions in these cells). 

### 2

6.2.5.3 Alveolar Macrophages

Within the gaseous exchange region of the lung, the first line of defense against 

### 3 microorganisms and nonviabl e particles that reach the alveolar surface is the AM. This 

### 4 resident phagocyte is responsible for a variety of activities, including the detoxification 

### 5 and removal of inhaled particles, maintenance of pulmonary sterility via destruction of 

### 6 microorganisms, and interaction with lymphocytes for immunologic protection. Under 

### 7 normal conditions, AMs seek out particles deposited on the alveolar surface and ingest 

### 8 them, thereby sequestering the particles from the vulnerable respiratory membrane. To 

### 9 adequately fulfi ll their defense function, the AMs must maintain active mobility, a high 

### 10 degree of phagocytic activity, and an optimally functioning biochemical and enzyme 

### 11 system for bactericidal activity and degradation of ingested material. As discussed in 

### 12 previous AQCD s, short periods of O 3 exposure can cause a reduction in the number of 

### 13 free AMs available for pulmonary defense, and these AMs are more fragile, less 

### 14 phagocytic, and have decreased lysosomal enzyme activities required for killing 

### 15 pathogens. For example, in results from earlier work in rabbits, a 2

- hour exposure to 

### 16
0.1 ppm O 3 inhibited phagocytosis and a 3

- hour exposure to 0.25 ppm decreased 

### 17 lysosomal enzyme activities ( Driscoll et al., 1987 ; Hurst et al., 1970 ) . Similarly, AMs 

### 18 from rats exposed to 0.1 ppm O 3 for 1 or 3 weeks exhibited reduced hydrogen peroxide 

### 19 production ( Cohen et al., 2002 ) . A controlled human exposure study reported decrements 

### 20 in the ability of alveo lar macrophages to phagocytize yeast following exposure of healthy 

### 21
volunteers to 80 to 100 ppb O 3 for 6.6

- hour during moderate exercise ( Devlin et al., 

### 22
1991 ) . Although the percentage of phagocytosis

- capable macrophages was unchanged by 

### 23
O 3 e xposure, the number of yeast engulfed was reduced when phagocytosis was 

### 24 complement

- dependent. However, there was no difference in the ability of macrophages 

### 25 to produce superoxide anion after O 3 exposure. These results are consistent with those 

### 26
from another controlled human exposure study in which no changes in the level of 

### 27 lysosomal enzymes or superoxide anion production were observed in macrophages 

### 28 lavaged from healthy human subjects exposed to 400 ppb O 3 for 2 hours with heavy 

### 29
intermittent exercise ( Koren et al., 1989 ) . More recently, Lay et al. (2007 ) observed no 

### 30 difference in phagocytic activity or oxidative burst capacity in macrophages or 

### 31 monocytes from sputum or blood collected from healthy volunteers after a 2

- hour 

### 32 exposure to 400 pp b O 3 with moderate intermittent exercise. However, another study 

### 33 found that oxidative burst and phagocytic activity in macrophages increased in GSTM1 

### 34 null subjects compared to GSTM1 positive subjects, who had relatively unchanged 

### 35

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– Do Not Cite or Quote 6

- 126 June 2012 macrophage function parame ters after an O 3 exposure identical to that of Lay et al. 

### 1
described above ( Alexis et al., 2009 ) . Collectively, these studies demonstrate that O 3 can 

### 2 affect multiple steps or aspects required for proper macrophage function, but any C

- R 

### 3 relationship appears complex and genotype may be a consideration. A few other recent 

### 4
studies have evaluated the effects of O 3 on macrophage function, but these are of 

### 5 questionable relevance due to the use of in vitro exposure systems and amphibian animal 

### 6
models ( Mikerov et al., 2008c ; Dohm et al., 2005 ; Klestadt et al., 2005 )

. 

### 7

6.2.5.4 Infection and Adaptive Immunity

General Effects on the Immune System

The effects of O 3 on the immune system are complex a nd dependent on the exposure 

### 8 regimen and the observation period. According to toxicological studies it appears that the 

### 9
T

- cell

- dependent functions of the immune system are more affected than B

- cell



### 10 dependent functions ( U.S. EPA, 2006b ) . Generally, there is an early immunosuppressive 

### 11
effect that subsides with continue d O 3 exposure, resulting in either a return to normal 

### 12 responses or an enhancement of immune responses. However, this is not always the case 

### 13 as Aranyi et al. Aranyi et al. (1983 ) showed decreased T

- cell mitogen reactions in mice 

### 14 after subchronic (90

- day) exposure to 0.1 ppm O 3 . Earlier studies report changes in cell 

### 15 populations in lymphatic tissues ( U.S. EPA, 2006b ) . A more recent study in mice 

### 16
demonstrated that numbers of certain T

- cell subsets i n the spleen were reduced after 

### 17 exposure to 0.6 ppm O 3 (10h/day x 15d) ( Feng et al., 2006 )

. 

### 18

The inflammatory effects of O 3 involve the innate immune system, and as such, O 3 can 

### 19 affect adaptive (or acquired) immunity via alterations in antigen presentation and 

### 20 costimulation by innate immune cells such as macrophages and dendritic cells. Several 

### 21
recent controlled h uman exposure studies demonstrate increased expression of molecules 

### 22 involved in antigen presentation or costimulation. Lay et al. (2007 ) collected sputum 

### 23 monocytes from healthy volunteers exposed to 400 ppb O 3 for 2 hours with moderate 

### 24
intermittent exercise and detected increases in HLA

- DR, used to present antigen to 

### 25
T

- cells, a nd CD86, a costimulatory marker necessary for T

- cell activation. Upregulation 

### 26
of HLA

- DR was also observed by Alexis et al. (2009 ) in sputum dendritic cells and 

### 27 macrophages from GSTM1 null subjects exposed to 400 ppb O 3 for 2 hours with 

### 28
moderate intermittent exercise . On airway monocytes from healthy volunteers 24 hours 

### 29 after exposure to 80 ppb O 3 for 6.6 hours with moderate intermittent exercise, HLA

- DR, 

### 30 CD86, and CD14 (a molecule involved in bacterial endotoxin reactivity) were increased, 

### 31 whereas CD80, a costimulato ry molecule of more heterogeneous function, was decreased 

### 32 ( Alexis et al., 2010 ) . Patterns of expression on macrophages were similar, except that 

### 33

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– Do Not Cite or Quote 6

- 127 June 2012 HLA

- DR was found to be significa ntly decreased after O 3 exposure and CD86 was not 

### 1 significa ntly altered. An increase in IL

- 12p70, a macrophage and dendritic cell product 

### 2
that activates T

- cells, was correlated with increased numbers of dendritic cells. It shoul d 

### 3 be noted that these results are reported as comparisons to baseline as there was no clean 

### 4
air control ( Alexis et al., 2010 ; Alexis et al., 2009 ) . Another controlled human exposure 

### 5 study reported no increase in IL

- 12p70 in sputum from healthy, atopic, or atopic 

### 6 asthmatic subjects following a 2

- hour exposure to 400 ppb O 3 with intermittent moderate 

### 7
exercise ( Hernandez et al., 2010 ) . Levels of HLA

- DR, CD14 and CD86 were not 

### 8 increased on macrophages collected from any of these subjects. It is difficult to compare 

### 9
these results to those of Lay et al. (2007 ) and Alexis et al. (2010 ) due to differences in O 3 

### 10 concentration, cell type examined, and timing of postexposure analysis. 

### 11

Although no controlled human exposure studies have examined the effects of O 3 on the 

### 12 ability to mount antigen

- sp ecific responses, upregulation of markers associated with 

### 13 innate immune activation and antigen presentation could potentially enhance adaptive 

### 14 immunity and increase immunologic responses to antigen. While this may bolster 

### 15 defenses against infection, it als o may enhance allergic responses (Section 6.2.6 ). 

### 16

In animal models, O 3 has been found to alter responses to antigenic stimulation. For 

### 17 example, ant ibody responses to a T

- cell

- dependent antigen were suppressed after a 

### 18
56

- day exposure of mice to 0.8 ppm O 3 , and a 14

- day exposure to 0.5 ppm O 3 decreased 

### 19 the antiviral antibody response following influenza virus infection ( Jakab and Hmieleski, 

### 20
1988 ) ; the latter impairment may pave the way for lowered resistanc e to re

- infection. The 

### 21 immune response is highly influenced by the temporal relationship between O 3 exposure 

### 22 and antigenic stimulation. When O 3 exposure preceded Listeria infection, there were no 

### 23 effects on delayed

- type hypersensitivity or splenic lymphoproliferative responses; 

### 24 however, when O 3 exposure occurred during or after Listeria infection was initiated, 

### 25 these immune responses were suppressed ( Van Loveren et al., 1988 ) . In another study, a 

### 26 reduction in mitogen activated T

- cell proliferation was observed after exposure to 

### 27
0.6 ppm O 3 for 15 days that could be ameliorated by antioxidant supplementation. 

### 28 Antigen

- specific proliferation decreased by 60%, indicating attenuation of the acqu ired 

### 29 immunity needed for subsequent memory responses ( Feng et al., 2006 ) . O 3 exposure also 

### 30
skewed the ex

- vivo c ytokine responses elicited by non

- specific stimulation toward 

### 31 inflammation, decreasing IL

- 2 and increasing IFN

- γ. Modest decreases in immune 

### 32 function assessed in the offspring of O 3 - exposed dams (mice) were observed by Sharkhuu 

### 33 et al. (2011 ) . The ability to mount delayed

- type hypersensitivity responses was 

### 34 significa ntly suppressed in 42 day

- old offspring when dams were exposed to 0.8 or 

### 35
1.2 ppm O 3 , but not 0.4 ppm, from gestational day 9

- 18. Humoral responses to 

### 36 immunization with sheep red blood c ells were unaffected, as were other immune 

### 37 parameters such as splenic populations of CD45+ T

- cells, iNKT

- cells, and levels of IFN

- 

### 38

### Draft

– Do Not Cite or Quote 6

- 128 June 2012 γ, IL

- 4, and IL

- 17 in the BALF. Generally, continuous exposure to O 3 impairs immune 

### 1 responses for the first several days of ex posure, followed by an adaptation to O 3 that 

### 2 allows a return of normal immune responses. Most species show little effect of O 3 

### 3 exposures prior to immunization, but show a suppression of responses to antigen in O 3 

### 4 exposures post

- immunization. 

### 5

Microbial Inf ection

Bacterial infection
A relatively large body of evidence shows that O 3 increases susceptibility to bacterial 

### 6 infections. The majority of studies in this area were conducted before the 1996 O 3 AQCD 

### 7 was published and many are included in Table 6

- 9 ( U.S. EPA, 1996j ) on page 6

- 53 of 

### 8 that document. Known contributing factors are impaired mucociliary streaming, altered 

### 9 chemotaxis/motility, defective phagocytosis of bacteria, decreased production of 

### 10 lysosomal enzymes or superoxide radicals by alveolar macrophages, and decreased IFN

- γ 

### 11 levels. In animal models of bacterial infection, exposure to 0.08 ppm O 3 increases 

### 12 streptococcus

- induced mortality, regardless of whether O 3 exposure precedes or follows 

### 13
infection ( Miller et al., 1978 ; Coffin and Gardner, 1972 ; Coffin et al., 1967 ) . Increases in 

### 14 mortality are due to the infectious agent, thereb y reflecting functional impairment of host 

### 15 defenses. Exercise and copollutants can enhance the effects of O 3 in infectivity models. 

### 16 Although both mice and rats exhibit impaired bactericidal macrophage activity after O 3 

### 17 exposure, mortality due to infection is only observed in mice. Additionally, although 

### 18 mice and humans share many host defense mechanisms, there is little compelling 

### 19 evidence from epidemiologic studies to suggest an association between O 3 exposure and 

### 20
decreased resistance to bacterial infectio n, and the etiology of respiratory infections is not 

### 21 easily identified via ICD codes (Section 6.2.7.3 ). 

### 22

Viral infection
Only a few studies, described in previous AQCDs, have examined the effects of O 3 

### 23 exposure on the outcome of viral respiratory infection [see Table 6

- 9 on page 6

- 53 of the 

### 24
1996 O 3 AQCD ( U.S. EPA, 1996j ) ]. Some studies show increased mortality, while others 

### 25 show diminished severity and in creased survival time. There is little to no evidence from 

### 26
studies of animals or humans to suggest that O 3 increases the incidence of respiratory 

### 27 viral infection in humans. In human volunteers infected with rhinovirus prior to O 3 

### 28 exposure (0.3 ppm for 5 co nsecutive days), no effect on viral titers, IFN

- γ production, or 

### 29 blood lymphocyte proliferative responses to viral antigen was observed ( Henderson et al., 

### 30
1988 ) . In vitro cell culture studies of human bronchial epithelial cells indicate O 3 - induced 

### 31
exacerbation of human rhinovirus infection ( Spannhake et al., 2002 ) , but this is of limited 

### 32
relevance. More recent studies on the interactions of O 3 and viral infections have not been 

### 33

### Draft

– Do Not Cite or Quote 6

- 129 June 2012 published. Natural kill er (NK) cells, which destroy virally infected cells and tumors in the 

### 1 lung, appear to be inhibited by higher concentrations of O 3 and either unaffected or 

### 2 stimulated at lower concentrations. Several studies show decreases in NK cell activity 

### 3 following acut e exposures ranging from 0.8 to 1 ppm ( Gilmour and Jakab, 1991 ; Van 

### 4 Loveren et al., 1990 ; Burleson et al., 1989 ) . However, Van Loveren et al. (1990 ) showed 

### 5
that a 1

- week exposur e to 0.2 or 0.4 ppm O 3 increased NK cell activity, and an urban 

### 6 pattern of exposure (base of 0.06 ppm with peaks of 0.25 ppm) had no effect on NK cell 

### 7 activity after 1, 3, 13, 52, or 78 weeks of exposure ( Selgrade et al., 1990 ) . A more rece nt 

### 8 study demonstrated a 35% reduction in NK cell activity after exposure of mice to 

### 9
0.6 ppm O 3 (10h/day x 15d) ( Fe ng et al., 2006 ) . The defective IL

- 2 production 

### 10 demonstrated in this study may impair NK cell activation. Alternatively, NK cell surface 

### 11 charge may be altered by ROS, decreasing their adherence to target cells ( Nakamura and 

### 12 Matsunaga, 1998 )

. 

### 13

6.2.5.5 Summary of Lung Host Defenses

Taken as a whole, the data clearly indicate that an acute O 3 exposure impairs the host 

### 14 defense capability of animals, primarily by depressing AM function and perhaps also by 

### 15 decreasing mucociliary clearance of inhaled particles and microorganisms. Coupled with 

### 16 limited evidence from controlled human exposure studies, this suggests that humans 

### 17 exposed to O 3 could be predisposed to b acterial infections in the lower respiratory tract. 

### 18 The seriousness of such infections may depend on how quickly bacteria develop 

### 19 virulence factors and how rapidly PMNs are mobilized to compensate for the deficit in 

### 20
AM function. It remains unclear how O 3 m ight affect antigen presentation and the 

### 21 costimulation required for T

- cell activation, given the mixed results from controlled 

### 22 human exposure studies, but there is toxicological evidence for suppression of T

- cell



### 23 dependent functions by O 3 , including reduct ions in antigen

- specific proliferation and 

### 24 antibody production, indicating the potential for impaired acquired immunity and 

### 25 memory responses. To date, a limited number of epidemiologic studies have examined 

### 26
associations between O 3 exposure and hospital adm issions or ED visits for respiratory 

### 27 infection, pneumonia, or influenza. Results have been mixed, and in some cases 

### 28 conflicting (see Section 6.2.7.2 and Section 6.2.7.3 ). With the exception of influenza, it is 

### 29 difficult to ascertain whether cases of respiratory infection or pneumonia are of vira l or 

### 30 bacterial etiology. A study that examined the association between O 3 exposure and 

### 31 respiratory hospital admissions in response to an increase in influenza intensity did 

### 32 observe an increase in respiratory hospital admissions ( Wong et al., 2009 ) , but 

### 33 information from toxicological studies of O 3 and viral infections is ambiguous. 

### 34

### Draft

– Do Not Cite or Quote 6

- 130 June 2012 6.2.6 Allergic and Asthma

- Related Responses

Effects resulting from combined exposures to O 3 and allergens have been studied in a 

### 1 variety of animal species, generally as models of experimental asthma. Pulmonary 

### 2 function and airways hyperresponsiveness in animal models of asthma are discussed in 

### 3
Section 6.2.1.3 and Section 6.2.2.2 . Previous evidence indicates that O 3 exposure skews 

### 4
imm une responses toward an allergic phenotype. For example, Gershwin et al. (1981 ) 

### 5

rep orted that O 3 (0.8 and 0.5 ppm for 4 days) exposure caused a 34

- fold increase in the 

### 6 number of IgE (allergic antibody)

- containing cells in the lungs of mice. In general, the 

### 7 number of IgE

- containing cells correlated positively with levels of anaphylactic 

### 8

s ensitivity. In humans, allergic rhinoconjunctivitis symptoms are associated with 

### 9
increases in ambient O 3 concentrations ( Riediker et al., 2001 ) . Recent controlled human 

### 10 exposure studies have observed O 3 - induced changes indicating allergic skewing. Airway 

### 11 eosinophils, which participate in allergic disease and inflammation, were observed to 

### 12 increase in atopic, mildly asthmatic volunteers 18 hours following a 7.6

- hour exposure to 

### 13
160 ppb O 3 with light intermittent exercise ( Peden et al., 1997 ) . No increase in airway 

### 14 eosinophils was observed 4 hours after exposure of healthy, atopic, or atopic asthmatic 

### 15 subjects to 400 ppb O 3 for 2 hours w ith moderate intermittent exercise ( Hernandez et al., 

### 16
2010 ) . However, atopic subjects did exhibit increased IL

- 5, a cytokine involved in 

### 17 eosinophil recruitment and activation, suggesting that perhaps these two studies observed 

### 18 the same effect at different time points . Epidemiologic studies discussed in Section 7.2.5 

### 19 describe an association between eosinophils and long

- term O 3 exposure, consistent with 

### 20
chronic ex posure studies in non

- human primates. Hernandez et al. (2010 ) also observed 

### 21 increased expression of high and low affinity IgE receptors on sputum macrophages from 

### 22 atopic asthmatics, which may enhance IgE

- dependent inflammation. Sputum levels of 

### 23
IL

- 4 and IL

- 13, both pro

- allergic cytokines that aid in the production of IgE, were 

### 24 unaltered in all groups. The lack of increase in IL

- 4 levels in sputum reported by 

### 25 Hernandez et al. (2010 ) , along with increased IL

- 5, is consistent with results from Bosson 

### 26 et al. (2003 ) , in wh ich IL

- 5 (but not IL

- 4 levels) increased in bronchial epithelial biopsy 

### 27 specimens following exposure of mild atopic asthmatics to 200 ppb O 3 for 2 hours with 

### 28
moderate intermittent exercise. IL

- 5 was not elevated in specimens obtained from healthy 

### 29 (non

- asth matic) O 3 - exposed subjects. Collectively, findings from these studies suggest 

### 30
that O 3 can induce or enhance certain components of allergic inflammation in atopic and 

### 31 atopic asthmatic individuals. 

### 32

Ozone enhances inflammatory and allergic responses to allerg en challenge in sensitized 

### 33
animals. Short

- term exposure (2 days) to 1 ppm O 3 exacerbated allergic rhinitis and lower 

### 34 airway allergic inflammation in Brown Norway rats, a rat strain that is comparatively less 

### 35
sensitive to O 3 than other rats or humans ( Wagner et al., 2009 ; 2007 ) . OVA

- sensitized 

### 36 rats were intranasally challenged with OVA on days 1 and 2, and exposed to 0 or 1 ppm 

### 37

### Draft

– Do Not Cite or Quote 6

- 131 June 2012 O 3 (8 h/day) on days 4 and 5. Analysis at day 6 in dicated that O 3 exposure enhanced 

### 1 intraepithelial mucosubstances in the nose and airways, induced cys

- LTs, MCP

- 1, and 

### 2
IL

- 6 production in BALF, and upregulated expression of the proallergic cytokines IL

- 5 

### 3
and IL

- 13. These changes were not evident in non

- all ergic controls. All of these 

### 4 responses were blunted by gamma

- tocopherol (γT; vitamin E) therapy. γT neutralizes 

### 5 oxidized lipid radicals, and protects lipids and proteins from nitrosative damage from 

### 6
NO

- derived metabolites. Farraj et al. (2010 ) exposed allergen

- sensitized adult male 

### 7
BALB/c mice to 0.5 ppm O 3 for 5 hours once per week for 4 weeks. Ozone exposure and 

### 8
O 3 /DEP (2.0 mg/m 3 ) co

- exposure of OVA

- sensitized mice elicited significa ntly greater 

### 9 serum IgE levels than in DEP

- exposed OVA

- sensitized mice (98% and 89% increases, 

### 10

respec tively). Ozone slightly enhanced levels of BAL IL

- 5, but despite increases in IgE, 

### 11
caused a significa nt decrease in BAL IL

- 4 levels. IL

- 10, IL

- 13, and IFN

- γ levels were 

### 12 unaffected. Lung resistance and elastance were unaffected in allergen sensitized mice 

### 13

e xposed solely to 0.5 ppm O 3 once a week for 4 weeks ( Farraj et al., 2010 ) . However, 

### 14

co

- exposure to O 3 and diesel exhaust particles increased lung resistance. 

### 15

In addition to exacerbating existing allergic responses, O 3 can also act as an adjuvant to 

### 16 produce sensitization in the respiratory tract. In a model of murine asthma, using OVA 

### 17 free of detectable endotoxin, inclusion of 1 ppm O 3 during the initial exposures to OVA 

### 18 (2 h, days 1 and 6) enhanced the inflammatory and allergic responses to subsequent 

### 19 allergen challenge ( Hollingsworth et al., 2010 ) . Compared to air exposed animals, 

### 20
O 3 - exposed mice exhibited significa ntly higher levels of total cells, macrophages, 

### 21 eosinophils, and PMNs in BALF, and increased total serum IgE. Pro

- allergic cytokines 

### 22
IL

- 4, and IL

- 5 were also significa ntly elevated, along with pleiotropic Th2 cytokine IL

- 9 

### 23 (associated with bronchial hyperresponsiveness) and pro

- inflammatory IL

- 17, produced 

### 24 by activated T

- cells . Based on lower inflammatory, IgE, and cytokine responses in 

### 25
Toll

- like receptor 4 deficient mice, the effects of O 3 seem to be dependent on TLR 4 

### 26 signaling, as are a number of other biological responses to O 3 according to studies by 

### 27 Hollingsworth et al. (2004 )
, Kleeberger et al. (2000 ) and Garantziotis et al. (2010 ) . The 

### 28 involvement of TLR 4, along with its endogenous ligan d, hyaluronan, in O 3 - induced 

### 29 responses described in these studies has been corroborated by a controlled human 

### 30 exposure study by Hernandez et al. (2010 ) , who found increased TLR 4 expression and 

### 31 elevated levels of hyaluronic acid in atopic and atopic ast hmatic volunteers exposed to 

### 32
400 ppb O 3 . This pathway is discussed in more detail in Chapter 5 . Examination of 

### 33 dendritic cells (DCs) from the draini ng thoracic lymph nodes indicated that O 3 did not 

### 34 enhance the migration of DCs from the lungs to the lymph nodes, nor did it alter the 

### 35 expression of functional DC markers such as CD40, MHC class II, or CD83. However, 

### 36
O 3 did increase expression of CD86, whi ch is generally associated with Th2 responses 

### 37 and is detected at higher levels on DCs from allergic asthmatics compared to those from 

### 38 healthy donors Chen et al. (2006b ) . Increased CD86 has also been observed on airway 

### 39

### Draft

– Do Not Cite or Quote 6

- 132 June 2012 cells collected from human subjects following exposure to O 3 in studies by Lay et al. 

### 1 (2007 ) and Alexis et al. (2009 ) , but not Hernandez et al. (2010 ) (study details described 

### 2
in Section 6.2.5.4 ). 

### 3

Ozone exposure during gestation has modest effects on allergy and asthma related 

### 4 endpoints in adult offspring. When dams were exposed to 1.2 ppm O 3 (but not 0.8 ppm) 

### 5 from gestational day 9

- 18, some allergic and inflammatory responses to OVA 

### 6 sensitization and challenge were reduced compared to air exposed controls. This included 

### 7 IgE levels and eo sinophils, and was only true of mice that were immunized early in life 

### 8 (PND 3) as opposed to later (PND 42), perhaps due to the proximity of O 3 and antigen 

### 9 exposure. The effects of gestational O 3 exposure on immune function have not been 

### 10 widely studied, an d although reductions in allergic endpoints are not generally observed 

### 11
in association with O 3 , other parameters of immune function were found to be reduced, so 

### 12 a more global immunosuppression may underlie these effects. 

### 13

In addition to pro

- allergic effects , O 3 could also make airborne allergens more allergenic. 

### 14
When combined with NO 2 , O 3 has been shown to enhance nitration of common protein 

### 15 allergens, which may increase their allergenicity Franze et al. (2005 )

. 

### 16

6.2.7 Hospital Admissions, Emergency Department Visits, and Physicians Visits

6.2.7.1 Summary of Findings from 2006 Ozone AQCD

The 2006 O 3 AQCD evaluated numerous respiratory ED visits and hospital admissions 

### 17 studies, which consisted primarily of time

- series studies conducted in the U.S., Canada, 

### 18 Europe, South America, Australia and Asia. Upon collectively evaluating the scientific 

### 19 evidence, the 2006 O 3 AQCD concluded that “the overall evidence supports a causal 

### 20 relationship between acute ambient O 3 exposures and increased respiratory morbidity 

### 21 resulting in increased ED visits and [hospital admissions] during the warm season” U.S. 

### 22 EPA (2006b ) . This conclusion was “strongly supported by the human clinical, animal 

### 23 toxicologic[al], and epidemiologic evidence for [O 3 - induced] lung function decrements, 

### 24 increased respiratory symptoms, airway inflammation, and airway hyperreactivity” U.S. 

### 25 EPA (2006b )

. 

### 26

Since the completion of the 2006 O 3 AQCD, relatively fewer studies conducted in the 

### 27 U.S., Can ada, and Europe have examined the association between short

- term exposure to 

### 28
ambient O 3 and respiratory hospital admissions and ED visits with a growing number of 

### 29 studies having been conducted in Asia. This section focuses primarily on multicity 

### 30

### Draft

– Do Not Cite or Quote 6

- 133 June 2012 studies be cause they examine the effect of O 3 on respiratory

- related hospital admissions 

### 1 and ED visits over a large geographic area using a consistent statistical methodology. 

### 2 Single

- city studies that encompass a large number of hospital admissions or ED visits, or 

### 3 included a long study

- duration were also evaluated because these studies have more 

### 4 power to detect whether an association exists between short

- term O 3 exposure and 

### 5 respiratory hospital admissions and ED visits compared to smaller single

- city studies. 

### 6
Addit ional single

- city studies were also evaluated within this section, if they were 

### 7 conducted in locations not represented by the larger single

- city and multicity studies, or 

### 8 examined population

- specific characteristics not included in the larger studies that may 

### 9 modify the association between short

- term O 3 exposure and respiratory

- related hospital 

### 10 admissions or ED visits. The remaining single

- city studies identified were not evaluated 

### 11 in this section due to factors such as inadequate study design or insufficie nt sample size. 

### 12

It should be mentioned that when examining the association between short

- term O 3 

### 13 exposure and respiratory health effects that require medical attention, it is important to 

### 14 distinguish between hospital admissions and ED visits. This is becau se it is likely that a 

### 15 small percentage of respiratory ED visits will be admitted to the hospital; therefore, 

### 16 respiratory ED visits may represent potentially less serious, but more common outcomes. 

### 17 As a result, in the following sections respiratory hospita l admission and ED visit studies 

### 18 are evaluated individually. Additionally, within each section, results are presented as 

### 19 either a collection of respiratory diagnoses or as individual diseases (e.g., asthma, COPD, 

### 20 pneumonia and other respiratory infections) in order to evaluate the potential effect of 

### 21
short

- term O 3 exposure on each respiratory

- related outcome. The ICD codes (i.e., ICD

- 9 

### 22
or ICD

- 10) that encompass each of these endpoints are presented in Table 6

- 26 along 

### 23 with the air quality characteristics of the city, or across all cities, included in each study 

### 24
evaluated in this section. 

### 25

### Draft

– Do Not Cite or Quote 6

- 134 June 2012 Table 6

- 26 Mean and upper percentile concentrations of respiratory

- related hospital admission and emergency department (ED) visit studies evaluated

Study Location Type of Visit (ICD9/10) Averaging Time Mean Concentration (ppb) a Upper Percentile Concentrations (ppb) a
Katsouyanni et al. (2009 ) b,c 90 U.S. cities (NMMAPS) d 32 European cities (APHEA) d
12 Canadian cities Hospital Admissions: NMMAPS: All respiratory (460

- 519) APHEA: All respiratory (460

- 519) 12 Canadian citi es: All respiratory (460

- 519) e 1

- h max NMMAPS: 50th: 34.9

- 60.0 APHEA: 50th: 11.0

- 38.1 12 Canadian cities: 50th: 6.7

- 8.3 NMMAPS: 75th: 46.8

- 68.8 APHEA: 75th: 15.3

- 49.4 12 Canadian cities: 75th: 8.4

- 12.4

Cakmak et al. (2006b ) 10 Canadian cities Hospital Admissions: All respiratory (466, 480

- 486, 490, 491, 492, 493, 494, 496) 24

- h avg 17.4 Max: 38.0

- 79.0

Biggeri et al

. (2005 ) c 4 Italian cities f Hospital Admissions: All respiratory (460

- 519) 8

- h max Warm season (May

- September):
5.7

- 60.0 95th: 86.1

- 90.0 Max: 107.5

- 115.1

Dales et al. (2006 ) 11 Canadian cities Hospital Admissions: Respiratory disorders (486, 768.9, 769, 770.8, 786, 799.0, 799.1) 24

- h avg 17.0 95th: 24.9

- 46.0

Lin et al. (2008a ) 11 New York regions Hospital Admis sions: Respiratory diseases (466, 490

- 493, 496) 8

- h max g 44.1 75th: 54.0 Max: 217.0

Wong et al. (2009 ) c Hong Kong Hospital Admissions: All respira tory (460

- 519) COPD (490

- 496) 8

- h max g 18.8 75th: 25.9 Max: 100.3

Medina

- Ramon et al. (2006 ) h 36 U.S. cities Hospital Admissions: COPD (490

- 496, excluding 493) Pneumonia (480

- 487) 8

- h max Warm (May

- September): 45.8 Cool (October

- April): 27.6 NR

Yang et al. (2005b ) Vancouver, Canada Hospital Admissions: COPD (490

- 492, 494, 496) 24

- h avg All year: 14.1 Winter (January

- March): 13.2 Spring (April

- June): 19.4 Summer (July

- September): 13.8 Fall (October

- December): 10.0 Max: 38.6

Zanobetti and Schwartz (2006 ) b Boston, MA Hospital Admissions: Pneumonia (480

- 487) 24

- h avg 22.4 75th: 31.0 95th: 47.6

Silverman and Ito (2010 ) b New York, NY Hospital Admissions: Asthma (493) 8

- h max Warm (April

- August): 41.0 75th: 53 90th: 68

### Draft

– Do Not Cite or Quote 6

- 135 June 2012 Study Location Type of Visit (ICD9/10) Averaging Time Mean Concentration (ppb) a Upper Percentile Concentrations (ppb) a

Stieb et al. (2009 ) 7 Canadian cities ED Visits: Asthma (493) COPD (490

- 492, 494

- 496) Respiratory infection (464, 466, 480

- 487) 24

- h avg 18.4 75th: 19.3

- 28.6

Tolbert et al. (2007 ) Atlanta, GA ED Visits: All respiratory (460

- 465, 460.0, 466.1, 466.11, 466.19, 477, 480

- 486, 491, 492, 493, 496, 786.07, 786.09) 8

- h max Warm: 53.0 75th: 67.0 90th: 82.1 Max: 147.5

Darrow et al. (2011a ) Atlanta, GA ED Visits: All respiratory (460

- 466, 477, 480

- 486, 491, 492, 493, 496, 786.09) 8

- h max Warm (March

- O ctober): 8

- h max: 53 8

- h max :75th: 67 8

- h max :Max: 148

1

- h max Warm (March

- October):
1

- h max: 62 1

- h max :75th: 76
1

- h max :Max: 180

24

- h avg Warm (March

- October):
24

- h avg: 30 24

- h avg :75th: 37
24

- h avg :Max: 81

Commute Warm (March

- October): Commute: 35 i Commute :75th: 45 Commute :Max: 106

Day

- time Warm (March

- October): Day

- time: 45 i Day

- time :75th: 58 Day

- time :Max: 123

Night

- time Warm (March

- October): Night

- time: 14 i Night

- time :75th: 22 Night

- time :Max: 64

Villeneuve et al. (2007 ) b Alberta, CAN ED Visits: Asthma (493) 8

- h max Summer (April

- September): 38.0 Winter (October

- March): 24.3 Summer: 75th: 46.0 Winter: 75th: 31.5

Ito et a l. (2007b ) New York, NY ED Visits: Asthma (493) 8

- h max All year: 30.4 Warm (April

- September): 42.7 Cold (October

- March): 18.0 All year: 95th: 68.0 Warm months: 95th: 77.0 Cold months: 95th: 33.0

Strickland et al. (2010 ) Atlanta, GA ED Visits: Asthma (493) Wheeze (786.07 after 10/1/98, 786.09 before 10/1/98) 8

- h max All year: 45.4 j
Warm (May

- October): 55.2 j
Cold (November

- April): 34.5 j NR

Mar and Koenig (2009 ) Seattle, WA ED Visits: Asthma (493

- 493.9) 1

- h max 8

- h max Warm (May

- October):
1

- h max: 38.6 8

- h max: 32.2 75th:
1

- h max: 45.5 8

- h max: 39.2

Arbex et al. (2009 ) Sao Paulo, Brazil ED Visits: COPD (J40

- 44) 1

- h max 48.8 75th: 61.0 Max: 143.8

### Draft

– Do Not Cite or Quote 6

- 136 June 2012 Study Location Type of Visit (ICD9/10) Averaging Time Mean Concentration (ppb) a Upper Percentile Concentrations (ppb) a

Orazzo et al. (2009 ) c 6 Italian cities ED Visits: Wheezing 8

- h max k Summer (April

- September): 21.1

- 44.3 Winter (October

- March): 11.5

- 27.9 NR

Burra et al. (2009 ) Toronto, Canada Physician Visits: ED Asthma (493) 1

- h max 33.3 95th: 66 Max: 121

Villeneuve et al. (2006b ) Toronto, Canada Physician Visits: Allergic rhinitis (177) 8

- h max 30.0 Max: 98.7

Sinclair et al. (2010 ) l Atlanta, GA Physician Visits: Asthma Upper respiratory infection Lower respiratory infection 8

- h max Total Study Period: All

- year: 44.0 25 mo Period: All

- year: 47.9 Warm: 61.2 Cold: 27.8
28 mo Period: All

- year: 40.7 Warm: 51.8 Cold: 26.0 NR

a Some studies did not present an overall value for the mean, middle and/or upper percentiles of the O 3 distribution; as a result, the range of the mean, middle, and/or upper percentiles across all of the cities included in the study are presented.

b Study o nly presented median concentrations.

c Study presented concentrations as μg/m 3 Concentration was converted to ppb using the conversion factor of 0.51 assuming standard temperature (25°C) and pressure (1 atm).

d A subset of the European and U.S. cities included in the mortality analyses were used in the hospital admissions analyses: 8 of the 32 European cities and 14 of 90 U.S. cities.

e Hospital admission data was coded using three classifications (ICD

- 10

- CA, ICD

- 9, and ICD

- 9

- CM). Attempts were made by t he original investigators to convert diagnosis from ICD

- 10

- CA back to ICD

- 9.

f Only 4 of the 8 cities included in the study collected O 3 data.

g O 3 measured from 10:00 a.m. to 6:00 p.m.

h Only 35 of the 36 cities included in the analysis had O 3 data.

i Commut e (7:00 a.m. to 10:00 a.m., 4:00 p.m. to 7:00 p.m.); day

- time (8:00 a.m. to 7:00 p.m.); Night

- time (12:00 a.m. to 6:00 a.m.).
j Means represent population

- weighted O 3 concentrations.

k O 3 measured from 8:00 a.m. to 4:00 p.m.

l This study did not report the IC D codes used for the conditions examined. The 25

- month period represents August 1998

- August 2000, and the 28

- month period represents September 2000

- December 2002. This study defined the warm months as April

– October and the cold months as November

- March.



### 6.2.7.2 Hospital Admission Studies

Respiratory Diseases

The association between exposure to an air pollutant, such as O 3 , and daily respiratory



### 1 related hospital admissions has primarily been examined using all respiratory

- related 

### 2 hospital admissions within the range of ICD

- 9 codes 460

- 519. Recent studies published 

### 3 since the 2006 AQCD ( U.S. EPA, 2006b ) attempt to further examine the effect of O 3 

### 4 exposure on respiratory

- related hospital admissions through a multicity design that 

### 5
examines O 3 effects across countries using a standardized methodology; multicity studies 

### 6

### Draft

– Do Not Cite or Quote 6

- 137 June 2012 that examine effects within one country; and multi

- and single

- city studies that a ttempt to 

### 1 examine potential modifiers of the O 3 - respiratory

- related hospital admission relationship. 

### 2

The Air Pollution and Health: A European and North American Approach (APHENA) 

### 3 study combined data from existing multicity study databases from Canada, Eur ope 

### 4 (APHEA2) ( Katsouyanni et al., 2001 ) , and the U.S. (NMMAPS) ( Samet et al., 2000 ) in 

### 5 order to “develop more reliable estimates of the potential acute effects of air pollution on 

### 6 human health [and] provide a common basis for [the] comparison of risks across 

### 7 geographic areas” ( Katsouyanni et al., 2009 ) . In an attempt to addr ess both of these 

### 8 issues, the investigators conducted extensive sensitivity analyses to evaluate the 

### 9 robustness of the results to different model specifications (e.g., penalized splines [PS] 

### 10 versus natural splines [NS]) and the extent of smoothing to contr ol for seasonal and 

### 11 temporal trends. The trend analyses consisted of subjecting the models to varying extent 

### 12 of smoothing selected either a priori (i.e., 3 df/year, 8 df/year, and 12 df/year), which was 

### 13 selected through exploratory analyses using between 2 and 20 df, or by using the absolute 

### 14 sum of the residuals of the partial autocorrelation function (PACF). Although the 

### 15 investigators did not identify the model they deemed to be the most appropriate for 

### 16 comparing the results across study locations, they di d specify that “overall effect 

### 17 estimates (i.e., estimates pooled over several cities) tended to stabilize at high degrees of 

### 18
freedom” ( Katsouyanni et al., 2009 ) . Therefore, in discussion of the results across the 

### 19
three st udy locations below, the 8 df/year results are presented for both the PS and NS 

### 20 models because: (1) 8 df/year is most consistent with the extent of temporal adjustment 

### 21 used in previous and recent large multicity studies in the U.S. (e.g., NMMAPS); (2) the 

### 22
risk estimates for 8 df/year and 12 df/year are comparable for all three locations; (3) the 

### 23 models that used the PACF method did not report the actual degrees of freedom chosen; 

### 24 and (4) the 3 df/year and the PACF method resulted in negative O 3 risk estimat es, which 

### 25 is inconsistent with the results obtained using more aggressive seasonal adjustments and 

### 26 suggests inadequate control for seasonality. Additionally, in comparisons of results across 

### 27 studies in figures, only the results from one of the spline model s (i.e., NS) are presented 

### 28 because it has been previously demonstrated that alternative spline models result in 

### 29 relatively similar effect estimates ( HEI, 2003 ) . This observation is consistent with the 

### 30 results of the APHENA analysis that was conducted with a higher number of degrees of 

### 31 freedom (e.g., ≥ 8 df/year) to account for temporal tre nds. 

### 32

Katsouyanni et al. (2009 ) examined respiratory hospital admissions for people aged 

### 33
65 years and older using 1

- h max O 3 data. The extent of hospital admission and O 3 data 

### 34
varied across the 3 datasets: Ca nadian dataset included 12 cities with data for 3 years 

### 35 (1993

- 1996) per city; European dataset included 8 cities with each city having data for 

### 36
between 2 and 8 years from 1988

- 1997; and the U.S. dataset included 14 cities with each 

### 37 city having data for 4 t o 10 years from 1985

- 1994 and 7 cities having only summer O 3 

### 38

### Draft

– Do Not Cite or Quote 6

- 138 June 2012 data. The investigators used a three

- stage hierarchical model to account for within

- city, 

### 1 within region, and between region variability. Results were presented individually for 

### 2 each region ( Figure 6

- 14 ; Table 6

- 27 ). Ozone and PM 10 concentrations were weakly 

### 3 correlated in all locations in the summer (r = 0.27

- 0.40), but not in the winter. 

### 4

In the Canadian cities, using all

- year data, a 40 ppb increase i n 1

- h max O 3 

### 5 concentrations at lag 0

- 1 was associated with an increase in respiratory hospital 

### 6 admissions of 8.9% (95% CI: 0.79, 16.8%) in a PS model and 8.1% (95% CI: 0.24, 

### 7 16.8%) in a NS model ( Katsouyanni et al., 2009 ) . The results were somewhat sensitive to 

### 8 the lag day selected, reduced when using a single

- day lag (e.g., lag 1) (PS: 6.0%; NS: 

### 9 5.5%) and increased when using a distributed lag model (PS: 18.6%; NS: 20.4%). When 

### 10 adjusting for PM 10 , the magnitude of the eff ect estimate was attenuated, but remained 

### 11 positive with it being slightly larger in the NS model (5.1% [95% CI:

- 6.6, 18.6%]) 

### 12 compared to the PS model (3.1% [95% CI:

- 8.3, 15.9%]). However, in the Canadian 

### 13 dataset the copollutant analysis was only conducte d using a 1

- day lag. The large 

### 14
confidence intervals for both models could be attributed to the reduction in days included 

### 15 in the copollutant analyses as a result of the every

- 6th

- day PM sampling schedule. When 

### 16 the analysis was restricted to the summer mont hs, stronger associations were observed 

### 17
between O 3 and respiratory hospital admissions across the lags examined, ranging from 

### 18 ~22 to 37% (the study does not specify whether these effect estimates are from a NS or 

### 19 PS model). Because O 3 concentrations across the cities included in the Canadian dataset 

### 20 are low (median concentrations ranging from 6.7

- 8.3 ppb [ Table 6

- 26 ]), the standardized 

### 21
increment of 40 p pb for a 1

- h max increase in O 3 concentrations represents an unrealistic 

### 22
increase in O 3 concentrations in Canada and increases the magnitude, not direction, of the 

### 23 observed risk estimate. As a result, calculating the O 3 risk estimate using the standardized 

### 24 increment does not accurately reflect the observed risk of O 3 - related respiratory hospital 

### 25 admissions. Although this increment adequately characterizes the distribution of 1

- h max 

### 26
O 3 concentrations across the U.S. and European datasets, it misrepresents t he observed O 3 

### 27 concentrations in the Canadian dataset. As a result in summary figures, for comparability, 

### 28 effect estimates from the Canadian dataset are presented for both a 5.1 ppb increase in 

### 29
1

- h max O 3 concentrations (i.e., an approximate interquartile range [IQR] increase in O 3 

### 30 concentrations across the Canadian cities) as well as the standardized increment used 

### 31 throughout the ISA. 

### 32

In Europe, weaker but positive associations were also observed in year round analyses; 

### 33 2.9% (95% CI: 0.63, 5.0%) in the PS model and 1.6% (95% CI:

- 1.7, 4.2%) in the NS 

### 34 model at lag 0

- 1 for a 40 ppb increase in 1

- h max O 3 concentrations ( Katsouyanni et al., 

### 35
2009 ) . Additionally, at lag 1, associations between O 3 and respiratory hospital admissions 

### 36 were also reduced, but in contrast to the lag 0

- 1 analysis, greater effects were observed in 

### 37 the NS model (2.9% [95% CI: 1.0, 4.9%]) compared to the PS model (1.5% [95% CI: 

### 38

### Draft

– Do Not Cite or Quote 6

- 139 June 2012 - 2.2, 5.4]). Unlike the Canadian analysis, a d istributed lag model provided limited 

### 1
evidence of an association between O 3 and respiratory hospital admissions. To compare 

### 2 with the Canadian results, with adjustment for PM 10 at lag 1, O 3 effect estimates were 

### 3 increased in the PS model (2.5% [95% CI: 0.39

- 4.8%]) and remained robust in the NS 

### 4 model (2.4% [95% CI: 0.08, 4.6%]). However, the European analysis also examined the 

### 5 effect of adjusting for PM 10 at lag 0

- 1 and found results were attenuated, but remained 

### 6 positive in both models (PS: 0.8% [95% CI:

- 2. 3, 4.0%]; NS: 0.8% [95% CI:

- 1.8, 

### 7 3.6%]). Unlike the Canadian and U.S. datasets, the European dataset consisted of daily 

### 8 PM data. The investigators did not observe stronger associations in the summer

- only 

### 9 analyses for the European cities at lag 0

- 1 (PS: 0. 4% [95% CI:

- 3.2, 4.0%]; NS: 0.2% 

### 10 [95% CI:

- 3.3, 3.9%]), but did observe some evidence for larger effects during the 

### 11 summer, an ~2.5% increase, at lag 1 in both models (the study does not present the extent 

### 12 of temporal smoothing used for these models). 

### 13

### Draft

– Do Not Cite or Quote 6

- 140 June 2012 Note: Black circles = all

- year results; open circles = all

- year results in copollutant model with PM 10 ; and red circles = summer only results. For Canada, lag days with an “a” next to them represent the risk estimates standardized to an approximate IQR of 5.1 ppb for a 1

- h max increase in O 3 concentration s.


### Figure 6

- 14 Percent increase in respiratory hospital admissions from natural spline models with 8 df/yr for a 40 ppb increase in 1

- h max ozone concentrat ions for each location of the APHENA study. Location

U.S.

Canada

Europe All

- Year

Summer

All

- Year

Summer

All

- Year

Summer ►

►

► Lag

1 1 0

- 1 0

- 1 DL (0

- 2)

0

- 1 1

1 1a 1 1a 0

- 1 0

- 1a DL (0

- 2) DL (0

- 2)a 1 1a 0

- 1 0

- 1a DL (0

- 2) DL (0

- 2)a

1 1 0

- 1 0

- 1 DL (0

- 2)

1 0

- 1

- 10

- 5 0 5 10 15 20 25 30 35 40 % Increase

### Draft

– Do Not Cite or Quote 6

- 141 June 2012 Table 6

- 27 Corresponding effect estimates for Figure 6

- 14.

Location * Season Lag a Copollutant % Increase (95% CI) b

U.S. All

- year 1 2.62 (0.63, 4.64)

1 PM 10 2.14 (

- 0.08, 4.40)

0

- 1 2.38 (0.00, 4.89)

0

- 1 PM 10 1.42 (

- 1.33, 4.23) DL(0

- 2) 3.34 (0.02

- 6.78)

Summer 0

- 1 2.14 (

- 0.63, 4.97)

1 2.78 (

- 0.02, 5.71)

Canada All

- year 1 5.54 (

- 0.94, 12.4)

1a 0.69 (

- 0.12, 1.50) a

1 PM 10 5.13 (

- 6.62, 18.6)

1a PM 10 0.64 (

- 0.87, 2.20) a

0

- 1 8.12 (0.24, 16.8)

0

- 1a 1.00 (0.03, 2.00) a
DL(0

- 2) 20.4 (4.07, 40.2) DL(0

- 2) a 2.4 (0.51, 4.40) a

Summer 1 21.4 (15.0, 29.0)

1a 2.50 (1.80, 3.30) a

0

- 1 32.0 (18.6, 47.7)

0

- 1 a 3.60 (2.20, 5.10) a
DL(0

- 2) 37.1 (11.5, 67.5) DL(0

- 2) a 4.1 (1.40, 6.80) a
Europe All

- year 1 2.94 (1.02, 4.89)

1 PM 10 2.38 (0.08, 4.64)

0

- 1 1.58 (

- 1.71, 4.15)

0

- 1 PM 10 0.87 (

- 1.79, 3.58) DL(0

- 2) 0.79 (

- 4.46, 6.37)

Summer 1 2.46 (

- 0.63, 5.54)

0

- 1 0.24 (

- 3.32, 3.91)

*For effect estimates in Figure 6

- 14

.
a For Canada, lag days with an “a” next to them represent the risk estimates standardized to an approximate IQR of 5.1 ppb for a 1

- h max increase in O 3 concentrations.

b Unless noted, risk est imates standardized to 40 ppb for a 1

- h max increase in O 3 concentrations.

For the U.S. in year round analyses, the investigators reported a 1.4% (95% CI:

- 0.9, 

### 1 3.9%) increase in the PS model and 2.4% (95% CI: 0.0, 4.9%) increase in the NS model 

### 2 in respir atory hospital admissions at lag 0

- 1 for a 40 ppb increase in 1

- h max O 3 

### 3 concentrations with similar results for both models at lag 1 ( Katsouyanni et al., 2009 )

. 

### 4 The distributed lag model provided results similar to those observed in the European 

### 5

### Draft

– Do Not Cite or Quote 6

- 142 June 2012 dataset with the PS model (1.1% [95% CI:

- 3.0, 5.3%]), but larger effects in the NS 

### 1 model (3.3% [95% CI: 0.02, 6.8%]), which is consistent with the Canadian results. With 

### 2 adjustment for PM 10 using the U.S. data (i.e., every

- 6th

- da y PM data), results were 

### 3 attenuated, but remained positive at lag 0

- 1 (PS: 0.6% [95% CI:

- 2.0, 3.3%]; NS: 1.4% 

### 4 [95% CI:

- 1.3, 4.2%]) which is consistent with the results presented for the European 

### 5 dataset. However, at lag 1, U.S. risk estimates remained ro bust to the inclusion of PM 10 in 

### 6 copollutant models as was observed in the Canadian and European datasets. Compared to 

### 7
the all

- year analyses, the investigators did not observe stronger associations in the 

### 8

summer

- only analysis at either lag 0

- 1 (~2.2%) or l ag 1 (~2.8%) in both the PS and NS 

### 9 models (the study does not present the extent of temporal smoothing used for these 

### 10 models). 

### 11

Several additional multicity studies examined respiratory disease hospital admissions in 

### 12 Canada and Europe. Cakmak et al. (2006b ) evaluated the assoc iation between ambient O 3 

### 13 concentrations and respiratory hospital admissions for all ages in 10 Canadian cities from 

### 14 April 1993 to March 2000. The primary objective of this study was to examine the 

### 15 potential modification of the effect of ambient air pollut ion on daily respiratory hospital 

### 16 admissions by education and income using a time

- series analysis conducted at the city



### 17 level. The authors calculated a pooled estimate across cities for each pollutant using a 

### 18 random effects model by first selecting the lag day with the strongest association from the 

### 19 city

- specific models. For O 3 , the mean lag day across cities that provided the strongest 

### 20 association and for which the pooled effect estimate was calculated was 1.2 days. In this 

### 21 study, all

- year O 3 concentration s were used in the analysis, and additional seasonal 

### 22 analyses were not conducted. Cakmak et al. (2006b ) reported a 4.4% increase (95% CI: 

### 23 2.2, 6.5%) in respiratory hospital admissions for a 20 ppb increase in 24

- hour average O 3 

### 24
concentrations. The investi gators only examined the potential effect of confounding by 

### 25 other pollutants through the use of a multipollutant model (i.e., two or more additional 

### 26 pollutants included in the model), which is difficult to interpret due to the potential 

### 27 multicollinearity b etween pollutants. Cakm ak et al. (2006b ) also conducted an extensive 

### 28 analysis of potential modifiers, specifically sex, educational attainment, and family 

### 29 income, on the association between air pollution and respiratory hospital admissions. 

### 30 When stratifying by sex, the increa se in respiratory hospital admissions due to short

- term 

### 31
O 3 exposure were similar in males (5.2% [95% CI: 3.0, 7.3%]) and females (4.2% 

### 32 [95% CI: 1.8, 6.6%]). In addition, the examination of effect modification by income 

### 33
found no consistent trend across the quartiles of family income. However, there was 

### 34 evidence that individuals with an education level less than the 9th grade were 

### 35 disproportionately affected by O 3 exposure (4.6% [95% CI: 1.8, 7.5%]) compared to 

### 36 individuals that completed grades 9

- 13 (1.7% [95 % CI:

- 1.9, 5.3%]), some university or 

### 37 trade school (1.4% [95% CI:

- 2.0, 5.1%]), or have a university diploma (0.66% [95% CI: 

### 38

- 3.3, 4.7%]). The association between O 3 and respiratory hospital admissions in 

### 39

### Draft

– Do Not Cite or Quote 6

- 143 June 2012 individuals with an education level less than the 9th grade was the strongest association 

### 1 across all of the pollutants examined. 

### 2

A multicity study conducted in Europe by Biggeri et al. (2005 ) examined the association 

### 3
between short

- term O 3 exposure and respiratory hospital admissions for all ages in four 

### 4 Italian cities from 1990 to 1999. In this study, O 3 was only measured during the warm 

### 5 season (May

- September). The authors examined associations between daily respiratory 

### 6 hospital admissions and short

- term O 3 exposure at the city

- level using a time

- series 

### 7 analysis. Pooled estimates were calculated by combining city

- specific estimates using 

### 8
fixed and ra ndom effects models. The investigators found no evidence of an association 

### 9
between O 3 exposure and respiratory hospital admissions in the warm season in both the 

### 10 random (0.1% [95% CI:

- 5.2, 5.7%]; distributed lag 0

- 3) and fixed effects (0.1% 

### 11 [95% CI:

- 5.2, 5.7%]; distributed lag 0

- 3) models for a 30 ppb increase in 8

- h max O 3 

### 12
concentrations. 

### 13

Additional studies examined associations between short

- term O 3 exposure and respiratory 

### 14 hospital admissions specifically in children. In a multicity study conducted in Canada, 

### 15 Dales et al. (2006 ) examined the association between all

- year ambient O 3 concentra tions 

### 16 and neonatal (ages 0

- 27 days) respiratory hospital admissions in 11 Canadian cities from 

### 17 1986 to 2000. The investigators used a statistical analysis approach similar to Cakmak et 

### 18 al. (2006b ) (i.e., time

- series analysis to examine city

- specific associations, and then a 

### 19

r andom effects model to pool estimates across cities). The authors reported that for O 3, 

### 20 the mean lag day across cities that provided the strongest association was 2 days. The 

### 21 authors reported a 5.4% (95% CI: 2.9, 8.0%) increase in neonatal respiratory hosp ital 

### 22
admissions for a 20 ppb increase in 24

- h avg O 3 concentrations at lag

- 2 days. The results 

### 23
from Dales et al. (2006 ) provide support for the associations observed in a smaller scale 

### 24 study that examined O 3 exposure and pediatric respiratory hospital admissions in 

### 25
New York state ( Lin et al., 2008a )

. Lin et al. (2008a ) , when examining single

- day lags of 

### 26
0 to 3 days, observed a positive association between O 3 a nd pediatric (i.e., <18 years) 

### 27 respiratory admissions at lag 2 (results not presented quantitatively) in a two

- stage 

### 28 Bayesian hierarchical model analysis of 11 geographic regions of New York state from 

### 29 1991 to 2001. Additionally, in copollutant models with PM 10 , collected every

- 6th day, the 

### 30 authors found region

- specific O 3 associations with respiratory hospital admissions 

### 31 remained relatively robust. 

### 32

Overall, the evidence from epidemiologic studies continues to support an association 

### 33
between short

- term O 3 ex posure and respiratory

- related hospital admissions, but it 

### 34 remains unclear whether certain factors (individual

- or population

- level) modify this 

### 35
association. Wong et al. (2009 ) examined the potential modification of the relationship 

### 36
between ambient O 3 (along with NO 2 , SO 2 , and PM 10 ) and respiratory hospital 

### 37

### Draft

– Do Not Cite or Quote 6

- 144 June 2012 admissions by influenza intensity in Hong Kong for the period 1996

– 2002. In this study 

### 1 air p ollution concentrations were estimated by centering non

- missing daily air pollution 

### 2 data on the annual mean for each monitor and then an overall daily concentration was 

### 3 calculated by taking the average of the daily centered mean across all monitors. Influe nza 

### 4 intensity was defined as a continuous variable using the proportion of weekly specimens 

### 5 positive for influenza A or B instead of defining influenza epidemics. This approach was 

### 6 used to avoid any potential bias associated with the unpredictable seasonal ity of influenza 

### 7 in Hong Kong where there are traditionally two seasonal peaks, which is in contrast to the 

### 8 single peaking influenza season in the U.S. ( Wong et al. , 2009 ) . In models that examined 

### 9 the baseline effect (i.e., without taking into consideration influenza intensity) of short



### 10
term O 3 exposure, the authors found a 3.6% (95% CI: 1.9, 5.3%) and 3.2% (95% CI: 1.0, 

### 11 5.4%) increase in respiratory hospital admi ssions at lag 0

- 1 for a 30 ppb increase in 

### 12
8

- h max O 3 concentrations for the all age and ≥ 65 age groups, respectively. When 

### 13 examining influenza intensity, Wong et al. (2009 ) reported that the association between 

### 14
short

- term exposure to O 3 and respiratory hospital admissions was stronger with higher 

### 15 levels of influenza intensity: additional increase in respiratory hospital admissions above 

### 16
baseline of 1.4% (95% CI: 0.24, 2.6%) for all age groups and 2.4% (95% CI: 0.94, 3.8%) 

### 17 for those 65 and older when influenza activity increased from 0% to 10%. No difference 

### 18 in effects was observed when stratifying by sex. 

### 19

Cause

- Specific Respiratory Outcomes

In the 2006 O 3 AQCD a limited number of studies were identified that examined the 

### 20
effect of short

- term O 3 exposure on cause

- specific respiratory hospital admissions. The 

### 21 limited evidence “reported positive O 3 associations with... asthma and COPD, 

### 22 especially... during the summer or warm season” ( U.S. EPA, 2006b ) . Of the studies 

### 23 evaluated since the completion of the 2006 O 3 AQCD, more have focused on identifying 

### 24
whether O 3 exposure is associated with specific respiratory

- related hospital admissions, 

### 25 including COPD, pneumonia, and asthma, but the overall body of evidence remains 

### 26

sm all. 

### 27

Chronic Obstructive Pulmonary Disease

Medina

- Ramon et al. (2006 ) examined the association between short

- term exposure to 

### 28
ambient O 3 and PM 10 concentrations and Medicare hospital admissions among 

### 29 individuals ≥ 65 years of age for COPD in 35 cities in the U.S. for the years 1986

- 1999. 

### 30
The cities included in this analysis were selected because they monitored PM 10 on a daily 

### 31 basis. In this study, city

- specific results were obtained using a monthly time

- stratified 

### 32

case

- crossover analysis. A meta

- analysis was then conducted using random effects 

### 33
models to combine the city

- specific results. All cities measured O 3 from May through 

### 34

### Draft

– Do Not Cite or Quote 6

- 145 June 2012 September, while only 16 of the cities had year

- round measurements. The authors 

### 1 reported a 1.6% increase (95% CI: 0.48, 2.9%) in COPD admissions for lag 0

- 1 in the 

### 2
warm season for a 30 ppb increase in 8

- h max O 3 concentrations. When examining 

### 3 single

- day lags, stronger associations were observed for lag 1 (2.9% [95% CI: 1.8, 4.0%]) 

### 4 compared to lag 0 (

- 1.5% [95% CI:

- 2.7,

- 0.24%]). The authors found no evidence of 

### 5 associations in cool season (

- 1.9% [95% CI:

- 3.6,

- 0.06%]; lag 0

- 1) or year round (0.24% 

### 6 [95% CI:

- 0.78, 1.2%]; lag 0

- 1) analyses. In a copollutant model restricted to days in 

### 7
which PM 10 was available, the association between O 3 and COPD hospital admissions 

### 8 remained robust. Of note, t he frequency of PM 10 measurements varied across cities with 

### 9 measurements collected either every 2, 3, or 6 days. The authors conducted additional 

### 10 analyses to examine potential modification of the warm season estimates for O 3 and 

### 11 COPD admissions by several city

- level characteristics: percentage living in poverty, 

### 12 emphysema mortality rate (as an indication of smoking), daily summer apparent 

### 13 temperature, and percentage of households using central air conditioning. Of the city



### 14 level characteristics examined, st ronger associations were only reported for cities with a 

### 15 smaller variability in daily apparent summer temperature. 

### 16

In a single

- city study conducted in Vancouver from 1994

- 1998, a location with low 

### 17
ambient O 3 concentrations ( Table 6

- 26 ), Yang et al. (2005b ) examined the association 

### 18
between O 3 and COPD. Ozone was moderately inversely correlated with CO (r = - 0.56), 

### 19
NO 2 (r = - 0.32), and SO 2 (r = - 0.34), and weakly inversely correl ated with PM 10 

### 20 (r = - 0.09), suggesting that the observed O 3 effect is likely not only due to a positive 

### 21 correlation with other pollutants. Yang et al. (2005b ) examined 1

- to 7

- day (e.g., (0

- 

### 22
6 days) lagged moving averages and observed an 8.8% (95% CI:

- 12.5, 32.6%) increase 

### 23
in COPD admissions for lag 0

- 3 per 20 ppb increase in 24

- h avg O 3 concentrations. In 

### 24

two

- pollutant models with every

- day data for NO 2 , SO 2 , and PM 10 at lag 0

- 3, O 3 risk 

### 25 estimates remained robust, but were increased slightly when CO was added to the model 

### 26 ( Figure 6

- 19 ; Table 6

- 29 ). 

### 27

In the study discussed a bove, Wong et al. (2009 ) also examined the potential 

### 28 modification of the relationship between ambient O 3 and COPD hospital admissions by 

### 29
influenza intensity. The authors also found evidence of an additional increase in COPD 

### 30 admissions above baseline when influenza activity increased from 0% to 10% of 1.0% 

### 31 (95% CI:

- 0.82, 2.9%) for all age groups and 2.4% (95% CI: 0.41, 4.4%) for those 65 and 

### 32
older. T he baseline increase in COPD hospital admissions at lag 0

- 1 for a 30 ppb increase 

### 33
in 8

- h max O 3 concentrations was 8.5% (95% CI: 5.6, 11.4%) for the all age and 4.2% 

### 34 (95% CI: 1.1, 7.3%) ≥ 65 age groups. 

### 35

### Draft

– Do Not Cite or Quote 6

- 146 June 2012 Pneumonia
In addition to COPD, Medina

- Ramon et al. (2006 ) examined the association between 

### 1
short

- term exposure to ambient O 3 and PM 10 concentrations and Medicare hospital 

### 2 admissions among individuals ≥ 65 years of age for pneumonia (ICD

- 9: 480

- 487). The 

### 3 authors reported an increase in pneumonia

- hospital admissions in the warm season (2.5% 

### 4 [95% CI: 1.6, 3.5%] for a 30 ppb increase in 8

- h max O 3 concentrations; lag 0

- 1). Similar 

### 5 to the results observed for COPD hospital admissions, pneumonia

- hospital admissions 

### 6 associations were stronger at lag 1 (2.6% [95% CI: 1.8, 3.4%]) compared to lag 0 (0.06% 

### 7 [95% CI:

- 0.72, 0.78%]), and no evidence o f an association was observed in the cool 

### 8 season or year round. In two

- pollutant models restricted to days for which PM 10 data was 

### 9 available, as discussed above, the association between O 3 exposure and pneumonia



### 10 hospital admissions remained robust (results not presented quantitatively). The authors 

### 11 also examined potential effect modification of the warm season estimates for O 3 - related 

### 12 pneumonia

- hospital admissions, as was done for COPD, by several city

- level 

### 13 characteristics. Stronger associations were repor ted in cities with a lower percentage of 

### 14 central air conditioning use. Across the cities examined, the percentage of households 

### 15 having central air conditioning ranged from 6 to 93%. The authors found no evidence of 

### 16
effect modification of the O 3 - pneumonia

- h ospital admission relationship when examining 

### 17 the other city

- level characteristics. 

### 18

Results from a single

- city study conducted in Boston did not support the results presented 

### 19 by Medina

- Ramon et al. (2006 )

. Zanobetti and Schwartz (2006 ) examined the association 

### 20
of O 3 and pneumonia Medicare hospital admissions for the period 1995

- 1999. Ozone was 

### 21 weakly positively co rrelated with PM 2.5 (r = 0.20) and weakly inversely correlated with 

### 22 black carbon, NO 2 , and CO (

- 0.25,

- 0.14, and

- 0.30, respectively). In an all

- year analysis, 

### 23 the investigators reported a 3.8% (95% CI:

- 7.9,

- 0.1%) decrease in pneumonia 

### 24
admissions for a 2 0 ppb increase in 24

- hour average O 3 concentrations at lag 0 and a 

### 25 6.0% (95% CI:

- 11.1,

- 1.4%) decrease for the average of lags 0 and 1. It should be noted 

### 26 that the mean daily counts of pneumonia admissions was low for this study, ~14 

### 27 admissions per day co mpared to ~271 admissions per day for Medina

- Ramon et al. 

### 28 (2 006 ) . However, in analyses with other pollutants Zano betti and Schwartz (2006 ) did 

### 29 observe positive associations with pneumonia

- hospital admissions, indicating that the low 

### 30 number of daily hospital admission counts probably did not influence the O 3 pneumonia



### 31 hospital admissions association in this study. 

### 32

Asthma
There are relatively fewer studies that examined the association between short

- term 

### 33 exposure to O 3 and asthma hospital admissions, presumably due to the limited power 

### 34 given the relative rarity of asthma hospital admissions compared to ED or physici an 

### 35

### Draft

– Do Not Cite or Quote 6

- 147 June 2012 visits. A study from New York City examined the association of 8

- h max O 3 

### 1 concentrations with severe acute asthma admissions (i.e., those admitted to the Intensive 

### 2 Care Unit [ICU]) during the warm season in the years 1999 through 2006 ( Silverman and 

### 3 Ito, 2010 ) . In this study, O 3 was moderately correlated with PM 10 (r = 0.59). When 

### 4 stratifying by age, the investigators reported positive associations with ICU asthma 

### 5
admissions for the 6

- to 18

- year age group (26.8% [95% CI: 1.4, 58.2%] for a 30 ppb 

### 6
increase in maximum 8

- h avg O 3 co ncentrations at lag 0

- 1), but little evidence of 

### 7 associations for the other age groups examined (<6 years, 19

- 49, 50+, and all ages). 

### 8 However, positive associations were observed for each age

- stratified group and all ages 

### 9
for non

- ICU asthma admissions, but again the strongest association was reported for the 

### 10
6

- to 18

- years age group (28.2% [95% CI: 15.3, 41.5%]; lag 0

- 1). In two

- pollutant 

### 11 models, O 3 effect estimates for both non

- ICU and ICU hospital admissions remained 

### 12 robust to adjustment for PM 2.5 . In an additional analysis, using a smooth function, the 

### 13 authors examined whether the shape of the C

- R curve for O 3 and asthma hospital 

### 14 admissions (i.e., both general and ICU for all ages) is linear. To account for the potential 

### 15 confounding effects of PM 2.5 , Silverman and Ito (2010 ) also included a smooth function 

### 16
of PM 2.5 lag 0

- 1. When comparing the curve to a linear fit line the authors found that the 

### 17 linear fit is a reasonable approximation of the C

- R relationship between O 3 and asthma 

### 18 hospital admissions around and below the level of the 1997 O 3 NAAQS ( Figure 6

- 15 ). 

### 19

### Draft

– Do Not Cite or Quote 6

- 148 June 2012 Note: The average of 0

- day and 1

- day lagged 8

- hour O 3 was used in a two

- pollutant model with PM 2.5 lag 0

- 1, adjusting for te mporal trends, day of the week, and immediate and delayed weather effects. The solid lines are smoothed fit data, with long broken l ines indicating 95% confidence bands. The density of lines at the bottom of the figure indicates sample size. Source: Reprin ted with permission of the American Academy of Allergy, Asthma & Immunology ( Silverman and Ito, 2010 )

. 

### Figure 6

- 15 Estimated relative risks (RRs) of asthma hospital admissions for 8

- h max ozone concent rations at lag 0

- 1 allowing for possible nonlinear relationships using natural splines.

Averting Behavior
The studies discussed above have found consistent positive associations between short



### 1
term O 3 exposure and respiratory

- related hospital admissions, ho wever, the strength of 

### 2 these associations may be underestimated due to the studies not accounting for averting 

### 3
behavior. As discussed in Section 4.6.5 , a recent study ( Neidell and Kinney, 2010 ; 

### 4 Neidell, 2009 ) conducted in Southern Calif ornia demonstrate that controlling for 

### 5
avoidance behavior increases O 3 effect estimates for respiratory hospital admissions, 

### 6 specifically for children and older adults. These studies show that on days where no 

### 7 public alert was issued warning of high O 3 con centrations there was an increase in asthma 

### 8 hospital admissions. Although only one study has examined averting behavior and this 

### 9

### Draft

– Do Not Cite or Quote 6

- 149 June 2012 study is limited to the outcome of asthma hospital admissions in one location (i.e., Los 

### 1 Angeles, CA) for the years 1989

- 1997, it does provide preliminary evidence indicating 

### 2 that epidemiologic studies may underestimate associations between O 3 exposure and 

### 3 health effects by not accounting for behavioral modification when public health alerts are 

### 4
issued. 

### 5

6.2.7.3 Emergency Department Visi t Studies

Overall, relatively fewer studies have examined the association between short

- term O 3 

### 6 exposure and respiratory

- related ED visits, compared to hospital admissions. In the 2006 

### 7
O 3 AQCD, positive, but inconsistent, associations were observed between O 3 and 

### 8 respiratory

- related ED visits with effects generally occurring during the warm season. 

### 9 Since the completion of the previous AQCD, larger studies have been conducted, in 

### 10 terms of sample size, study duration, and in some cases multiple cities, to exa mine the 

### 11
association between O 3 and ED visits for all respiratory diseases, COPD, and asthma. 

### 12

Respiratory Disease
A large single

- city study conducted in Atlanta, by Tolbert et al. (2007 ) , and subsequently 

### 13

re analyzed by Darrow et al. (2011a ) using different air quality data, provides evidence 

### 14
for an association between short

- term exposures to ambient O 3 concentrations and 

### 15 respiratory ED visits. Tolbert et al. (2007 ) examined the association between air 

### 16 pollution, both gaseous pollutants and PM and its components, and respiratory disease 

### 17
ED vis its in all ages from 1993 to 2004. The correlations between O 3 and the other 

### 18 pollutants examined ranged from 0.2 for CO and SO 2 to 0.5

- 0.6 for the PM measures. 

### 19 Using an a priori average of lags 0

- 2 for each air pollutant examined, the authors reported 

### 20
a 3. 9% (95% CI: 2.7, 5.2%) increase in respiratory ED visits for a 30 ppb increase in 

### 21
8

- h max O 3 concentrations during the warm season [defined as March

- October in Darrow 

### 22 et al. (2011a ) ]. In copollutant models, limited to days in which data for all pollutants were 

### 23 available, O 3 respiratory ED visits associations with CO, NO 2 , and PM 10 , were attenuated, 

### 24 but remained positive (results not presented quantitatively). 

### 25

Darrow et al. (2011a ) examined the same health data as Tolbert et al. (2007 ) , but used air 

### 26 quality data from one centrally located monitor instead of the average of multiple 

### 27 monitors. This study primarily focused on exploring whether differences exist in the 

### 28
association between O 3 exposure and respiratory

- related ED visits depending on the 

### 29 exposure metric used (i.e., 8

- h max, 1

- h max, 24

- hour average, commuting period [7:00 

### 30 a.m. to 10:00 a.m.; 4:00 p.m. to 7:00 p.m.], day

- time [8:00 a.m. to 7:00 p.m.] and night



### 31 time [12:00 a.m. to 6:00 a.m.]). An ancillary analysis of the spatial variability of each 

### 32 exposure metric conducted by Darrow et al. (2011a ) found a rather homogenous spatial 

### 33

### Draft

– Do Not Cite or Quote 6

- 150 June 2012 distribution of O 3 concentrations (r~>0.8) as the distance from the central monitor 

### 1 increased from 10 km to 60 km for all exposure durations, except the night

- time metric. 

### 2 The relatively high spatial correlation gives confidence in the use of a single monitor and 

### 3 the resulting risk estimates. To examine the association between th e various O 3 exposure 

### 4 metrics and respiratory ED visits, the authors conceptually used a time

- stratified case



### 5 crossover framework where control days were selected as those days within the same 

### 6 calendar month and maximum temperature as the case day. However , instead of 

### 7 conducting a traditional case

- crossover analysis, the authors used a Poisson model with 

### 8 indicator variables for each of the strata (i.e., parameters of the control days). Darrow et 

### 9 al. (2011a ) found using an a prior lag of 1 day, the results were somewhat variable across 

### 10 exposure metrics. The strongest associations with respiratory ED visits were found when 

### 11 using the 8

- h max, 1

- h max, and day

- time exposure metrics with weaker associations 

### 12 using the 24

- h avg and commuting period exposure metrics; a negative association was 

### 13 observed when using the night

- time exposure metric ( Figure 6

- 16 ). These results indicate 

### 14 that using the 24

- h avg exposure met ric may lead to smaller O 3 - respiratory ED visits risk 

### 15 estimates due to: (1) the dilution of relevant O 3 concentrations by averaging over hours 

### 16 (i.e., nighttime hours) during which O 3 concentrations are known to be low and (2) 

### 17 potential negative confounding by other pollutants (e.g., CO, NO 2 ) during the nighttime 

### 18
hours ( Darrow et al., 2011a )

. 

### 19

### Draft

– Do Not Cite or Quote 6

- 151 June 2012 Source: Reprinted with permission of Nature Publishing Group ( Darrow et al., 2011a )

. 

### Figure 6

- 16 Risk ratio for respiratory ED visits and differen t ozone exposure metrics in Atlanta from 1993

- 2004.

In an additional study conducted in 6 Italian cities, Orazzo et al. (2009 ) examined 

### 1 respiratory ED visits for ages 0

- 2 years in 6 Italian cities from 1996 to 2000. Howeve r, 

### 2 instead of identifying respiratory ED visits using the traditional approach of selecting 

### 3 ICD codes as was done by Tolbert et al. (2007 ) and Darrow et al. (2011a )
, Orazzo et al. 

### 4 (2009 ) used data on wheeze extracted from medical records as an indicator of lower 

### 5 respiratory disease. This study examined daily counts of wheeze in relation to air 

### 6 pollution using a time

- stratified case

- crossover approach in which control days were 

### 7 matched on day of week in the same month and year as the case day. The authors found 

### 8
no evidence of an association between 8

- h max O 3 concentrations and respiratory ED 

### 9 visits in children aged 0

- 2 years in models that examined both single

- day lags and 

### 10 moving averages of lags from 0

- 6 days in year

- round and seasonal analyses (i.e., warm 

### 11 and cool seasons). In all

- year analyses, the percent increase in total wheeze ranged from

- 

### 12
1.4% to

- 3.3% for a 0

- 1 to 0

- 6 d ay lag, respectively. 

### 13

### Draft

– Do Not Cite or Quote 6

- 152 June 2012 COPD
Stieb et al. (2009 ) also examined the association between short

- term O 3 exposure and 

### 1
COPD ED visits in 7 Canadian cities. Acros s cities, in an all

- year analysis, O 3 was found 

### 2 to be positively associated with COPD ED visits (2.4% [95% CI:

- 1.9, 6.9%] at lag 1 and 

### 3 4.0% [95% CI:

- 0.54, 8.6%] at lag 2 for a 20 ppb increase in 24

- h avg O 3 concentrations). 

### 4 In seasonal analyses, larger e ffects were observed between O 3 and COPD ED visits 

### 5 during the warm season (i.e., April

- September) 6.8% [95% CI: 0.11, 13.9%] (lag day not 

### 6 specified); with no associations observed in the winter season. Stieb et al. (2009 ) also 

### 7 examined associations between respiratory

- related ED visits, including COPD, and air 

### 8 pollution at sub

- daily time scales (i.e., 3

- h avg of ED visits versus 3

- h avg pollutant 

### 9
concentrati ons) and found no evidence of consistent associations between any pollutant 

### 10 and any respiratory outcome. 

### 11

In a single

- city study, Arbex et al. (2009 ) examined the association between COPD and 

### 12 several ambient air pollutants, including O 3 , in Sao Paulo, Brazil for the years 2001

- 2003 

### 13
for individuals over th e age of 40. Associations between O 3 exposure and COPD ED 

### 14 visits were examined in both single

- day lag (0

- 6 days) and polynomial distributed lag 

### 15 models (0

- 6 days). In all

- year analyses, O 3 was not found to be associated with an 

### 16 increase in COPD ED visits (r esults not presented quantitatively). The authors also 

### 17 conducted stratified analyses to examine the potential modification of the air pollutant



### 18 COPD ED visits relationship by age (e.g., 40

- 64, >64) and sex. In these analyses O 3 was 

### 19
found to have an increas e in COPD ED visits for women, but not for men or either of the 

### 20 age groups examined. 

### 21

Asthma
In a study of 7 Canadian cities, Stieb et al. (2009 ) also exam ined the association between 

### 22 exposure to air pollution (i.e., CO, NO 2 , O 3 , SO 2 , PM 10 , PM 2.5 , and O 3 ) and asthma ED 

### 23
visits. Associations between short

- term O 3 exposure and asthma ED visits were examined 

### 24 at the city level and then pooled using either fixed or random effects models depending 

### 25 on whether heterogeneity among effect estimates was found to be statistically significa nt. 

### 26 Across cities, in an all

- year an alysis, the authors found that short

- term O 3 exposure was 

### 27 associated with an increase (4.7% [95% CI:

- 1.4, 11.1%] at lag 1 and 3.5% [95% CI: 

### 28 0.33, 6.8%] at lag 2 for a 20 ppb increase in 24

- h avg O 3 concentrations) in asthma ED 

### 29
visits. The authors did not present the results from seasonal analyses for asthma, but 

### 30 stated that no associations were observed between any pollutant and respiratory ED visits 

### 31 in the winter season. As stated previously, in analyses of 3

- h avg O 3 concentrations, the 

### 32
authors observed no evidence of consistent associations between any pollutant and any 

### 33 respiratory outcome, including asthma. A single

- city study conducted in Alberta, Canada 

### 34 Villeneuve et al. (2007 ) from 1992

- 2002 among individuals two years of age and older 

### 35

### Draft

– Do Not Cite or Quote 6

- 153 June 2012 provides additional support for the findings from Stieb et al. (2009 ) , but also attempts to 

### 1 identify those lifestages (i.e., 2

- 4, 5

- 14, 15

- 44, 45

- 64, 65

- 74, or 75+) at greatest risk to 

### 2
O 3 - induced asthma ED visits. In a time

- referent case

- crossover analysis, Villeneuve et al. 

### 3
found an increase i n asthma ED visits in an all

- year analysis across all ages (12.0% 

### 4 [95% CI: 6.8, 17.2] for a 30 ppb increase in max 8

- h avg O 3 concentrations at lag 0

- 2) 

### 5 with associations being stronger during the warmer months (19.0% [95% CI: 11.9, 28.1]). 

### 6
When stratified by age, the strongest associations were observed in the warm season for 

### 7
individuals 5

- 14 (28.1% [95% CI: 11.9, 45.1]; lag 0

- 2) and 15

- 44 (19.0% [95% CI: 8.5, 

### 8 31.8]; lag 0

- 2). These associations were not found to be confounded by the inclusion of 

### 9
aeroaller gens in age

- specific models. 

### 10

Several additional single

- city studies have also provided evidence of an association 

### 11
between asthma ED visits and ambient O 3 concentrations. Ito et al. (2007b ) examined the 

### 12
association between short

- term exposure to air pollution and asthma ED visits for all ages 

### 13
in New York Cit y from 1999 to 2002. Similar to Darrow et al. (2011a ) , when examining 

### 14 the spatial distribution of O 3 concentrations, Ito et al. (2007b ) found a rather homogenous 

### 15 distribution (r~≥ 0.80) when examining monitor

- to

- monitor correlations at distances up to 

### 16
20 miles. Ito et al. (2007b ) used three different weather models with varying extent of 

### 17 smoothing to account for temporal relationships and multicollinearity among pollutants 

### 18 and meteorological variables (i.e., temperature and dew point) to examine the effect of 

### 19 model selection on the air pollutant

- asthma ED visit relationship. When examining O 3 , 

### 20
the authors reported a positive association with asthma ED visits, during the warm season 

### 21 across the models (ranging from 8.6 to 16.9%) and an inverse association in the cool 

### 22 season (ranging from

- 23.4 to

- 25.1%), at lag 0

- 1 for a 30 ppb increase in 8

- h max O 3 

### 23

concent rations. Ito et al. (2007b ) conducted copollutant mo dels using a simplified version 

### 24 of the weather model used in NMMAPS analyses (i.e., terms for same

- day temperature 

### 25
and 1

- 3 day average temperature). The authors found that O 3 risk estimates were not 

### 26 substantially changed in copollutant models that used eve ry

- day data for PM 2.5 , NO 2 , 

### 27
SO 2 , and CO during the warm season ( Figure 6

- 19 ; Table 6

- 29 ). 

### 28

### Draft

– Do Not Cite or Quote 6

- 154 June 2012 Note: The reference for the rate ratio is the estimated rate at the 5th percentile of the pollutant concentration. Estimates are presented for the 5th percentile through the 95th percentile of pollutant concen trations due to instability in the C

- R estimates at the distribution tails. Source: Reprinted with permission of American Thoracic Society ( Strickland et al., 2010 )

. 

### Figure 6

- 17 Loess C

- R estimates and twice

- standard error estimates from generalized additive models for associations between 8

- h max 3

- day average ozone concentrations and ED visits for pediatric asthma.

Strickland et al. (2010 ) examined the association between O 3 exposure and p ediatric 

### 1 asthma ED visits (ages 5

- 17 years) in Atlanta between 1993 and 2004 using air quality 

### 2 data over the same years as Darrow et al. (2011a ) and Tol bert et al. (2007 ) . However, 

### 3
unlike Darrow et al. (2011a ) and Tolbert et al. (2007 ) , which used single centrally located 

### 4 monitors or an average of monitors, respectively, Strickland et al. (2010 ) used 

### 5 population

- weighting to combine daily pollutant concentrations across monitors. In this 

### 6 study, the authors developed a statis tical model using hospital

- specific time

- series data 

### 7 that is essentially equivalent to a time

- stratified case

- crossover analysis (i.e., using 

### 8 interaction terms between year, month, and day

- of

- week to mimic the approach of 

### 9 selecting referent days within the same month and year as the case day). The authors 

### 10 observed a 6.4% (95% CI: 3.2, 9.6%) increase in ED visits for a 30 ppb increase in 

### 11
8

- h max O 3 concentrations at lag 0

- 2 in an all

- year analysis. In seasonal analyses, 

### 12 stronger associations were observed du ring the warm season (i.e., May

- October) (8.4% 

### 13 [95% CI: 4.4, 12.7%]; lag 0

- 2) than the cold season (4.5% [95% CI:

- 0.82, 10.0%]; lag 0

- 

### 14 2). Strickland et al. (2011 ) confirmed these findings in an additional analysis using the 

### 15
same d ataset, and found that the exposure assignment approach used (i.e., centrally 

### 16

### Draft

– Do Not Cite or Quote 6

- 155 June 2012 located monitor, unweighted average across monitors, and population

- weighted average 

### 1 across monitors) did not influence pediatric asthma ED visit risk estimates for spatially 

### 2
hom ogeneous pollutants such as O 3 . 

### 3

In copollutant analyses conducted over the entire dataset for the gaseous pollutants 

### 4 (i.e., (CO, NO 2 ), and limited to a subset of years (i.e., 1998

- 2004) for which daily PM 

### 5 data (i.e., PM 2.5 elemental carbon, PM 2.5 sulfate) were available, Strickland et al. (2010 ) 

### 6
found that O 3 risk estimates were not substantially changed when controlling for other 

### 7 pollutants (results not presented quantitatively). The authors also examined the C

- R 

### 8 relationship between O 3 exposu re and pediatric asthma ED visits and found that both 

### 9 quintile and loess C

- R analyses ( Figure 6

- 17 ) suggest that there are elevated associations 

### 10
with O 3 at 8

- h max concentrations as low as 30 ppb. These C

- R analyses do not provide 

### 11
evidence of a threshold level. 

### 12

In a single

- city study conducted on the West coast, Mar and Koenig ( 2009 ) examined the 

### 13
association between O 3 exposure and asthma ED visits (ICD

- 9 codes: 493

- 493.9) for 

### 14 children (<18) and adults (≥ 18) in Seattle, WA from 1998 to 2002. Of the total number 

### 15 of visits over the study duration, 64% of visits in the age group <18 comprised boys, and 

### 16 70% of visits in the ≥ 18 age group comprised females. Mar and Koenig (2009 ) 

### 17
conducted a time

- series analysis using both 1

- h max and max 8

- h avg O 3 conc entrations. 

### 18 A similar magnitude and pattern of associations was observed at each lag examined using 

### 19
both metrics. Mar and Koenig (2009 ) presented results for single day lags of 0 to 5 days, 

### 20 but found consistent positive associations across individual lag days which supports the 

### 21 findings from the studies discussed above that examined multi

- day exposures. For 

### 22 children, consistent positive associations were observed across all la gs, ranging from a 

### 23
19.1

- 36.8% increase in asthma ED visits for a 30 ppb increase in 8

- h max O 3 

### 24 concentrations with the strongest associations observed at lag 0 (33.1% [95% CI: 3.0, 

### 25 68.5]) and lag 3 (36.8% [95% CI: 6.1, 77.2]). O 3 was also found to be posit ively 

### 26 associated with asthma ED visits for adults at all lags, ranging from 9.3

- 26.0%, except at 

### 27 lag 0. The slightly different lag times for children and adults suggest that children may be 

### 28 more immediately responsive to O 3 exposures than adults Mar and Koenig (2009 )

. 

### 29

Respiratory Infection
Although an increasing number of studies have examined the association between O 3 

### 30 exposure and cause

- specific respiratory ED visits this tren d has not included an extensive 

### 31
examination of the association between O 3 exposure and respiratory infection ED visits. 

### 32 Stieb et al. (2009 ) also examined t he association between short

- term O 3 exposure and 

### 33 respiratory infection ED visits in 7 Canadian cities. In an all

- year analysis, there was no 

### 34
evidence of an association between O 3 exposure and respiratory infection ED visits at any 

### 35 lag examined (i.e., 0, 1 , and 2). Across cities, respiratory infections comprised the single 

### 36

### Draft

– Do Not Cite or Quote 6

- 156 June 2012 largest diagnostic category, approximately 32%, of all the ED visits examined, which 

### 1 also included myocardial infarction, heart failure, dysrhythmia, asthma, and COPD. 

### 2

6.2.7.4 Outpatient and Phys ician Visit Studies

Several studies have examined the association between ambient O 3 concentrations and 

### 3 physician or outpatient (non

- hospital, non

- eD) visits for acute conditions in various 

### 4 geographic locations. Burra et al. (2009 ) examined asthma physician visits among 

### 5 patients aged 1

- 17 and 18

- 64 years in Toronto, Canada from 1992 to 2001. The authors 

### 6
fou nd little or no evidence of an association between asthma physician visits and O 3 ; 

### 7 however, seasonal analyses were not conducted. It should be noted that in this study, 

### 8
most of the relative risks for O 3 were less than one and statistically significa nt, per haps 

### 9 indicating an inverse correlation with another pollutant or an artifact of the strong 

### 10 seasonality of asthma visits. Villeneuve et al. (2006b ) also focused on physician visits to 

### 11
examine the effect of short

- term O 3 exposure on allergic rhinitis among individuals aged 

### 12
65 or older in Toronto from 1995 to 2000. The authors did not observe a ny evidence of 

### 13 an association between allergic rhinitis physician visits and ambient O 3 concentrations in 

### 14 single

- day lag models in an all

- year analysis (results not presented quantitatively). 

### 15

In a study conducted in Atlanta, Sinclair et al. (2010 ) examined the association of acute 

### 16 asthma and respiratory infection (e.g., upper respiratory infections and lower respiratory 

### 17 infections) outpatient visits from a managed care organization with ambient O 3 

### 18 concentrations as well as multiple PM size fractions and species from August 1998 

### 19 through December 2002. The authors separated the analysis into two time periods (the 

### 20
first 25 months of the study period and the second 28 months of the study period), in 

### 21 order to compare the air pollutant concentrations and relationships between air pollutants 

### 22 and acute respiratory visits for the 25

- month time

- period examined in Sinclair and 

### 23 Tolsma (2004 ) to an additional 28

- month time

- period of available data from the Atlanta 

### 24 Aerosol Research Inhalation Epidemiology Study (ARIES). The authors found little 

### 25
evidence of an association between O 3 and asthma visits, for either children or adults, or 

### 26 respiratory infection visits in all

- year analyses and seasonal analyses. For example, a 

### 27 slightly elevated relative risk (RR) for childhood asthma visits was observed during the 

### 28
25

- month period in the cold season (RR: 1.12 [95% CI: 0.86, 1.41]; lag 0

- 2 for a 30 ppb 

### 29
increase in 8

- h max O 3 ), but not in the warm season (RR: 0.97 [95% CI: 0.86, 1.10]; lag 

### 30
0

- 2). During the 28

- month period at lag 0

- 2, a slightly larger positive effect was observed 

### 31 during the warm season (RR: 1.06 [95% CI: 0.97, 1.17]), compared to the cold season 

### 32 (RR: 1.03 [95% CI: 0.87, 1.21]). Overall, these results contradict those from Strickland et 

### 33 al. (2010 ) discus sed above. Although the mean number of asthma visits and O 3 

### 34
concentrations in Sinclair et al. (2010 ) and Strickland et al. (2010 ) are simil ar the 

### 35

### Draft

– Do Not Cite or Quote 6

- 157 June 2012 difference in results between the two studies could potentially be attributed to the severity 

### 1
of O 3 - induced asthma exacerbations (i.e., more severe symptoms requiring a visit to a 

### 2 hospital) and behavior, such as delaying a visit to the doctor for le ss severe symptoms. 

### 3

6.2.7.5 Summary

The results of the recent studies evaluated largely support the conclusion of the 2006 O 3 

### 4 AQCD. While fewer studies were published overall since the previous review, several 

### 5 multicity studies (e.g., Cakmak et al., 2006b ; Dales et al., 2006 ) and a multi

- continent 

### 6 study ( Kats ouyanni et al., 2009 ) provide supporting evidence for an association between 

### 7
short

- term O 3 exposure and an increase in respiratory

- related hospital admissions and ED 

### 8
visits. Across studies, different ICD

- 9 codes were used to define total respiratory cau ses, 

### 9 which may contribute to some heterogeneity in the magnitude of association. These 

### 10 findings are supported by single

- city studies that used different exposure assignment 

### 11 approaches (i.e., average of multiple monitors, single monitor, population

- weighted 

### 12 average) and averaging times (i.e., 1

- h max and 8

- h max). 

### 13

Collectively, in both single

- city and multicity studies there is continued evidence for 

### 14 increases in both hospital admissions and ED visits when examining all respiratory 

### 15
outcomes combined. Additio nally, recent studies published since the 2006 O 3 AQCD 

### 16 support an association between short

- term O 3 exposure and asthma ( Strickland et al., 

### 17
2010 ; Stieb et al., 2009 ) and COPD ( Stieb et al., 2009 ; Medina

- Ramon et al., 2006 ) 

### 18 hospital admissions and ED visits, with more limited evidence for pneumonia

- hospital 

### 19
admissions and ED visits ( Medina

- Ramon et al., 2006 ; Zanobetti and Schwartz, 2006 )

. 

### 20 As with total respiratory causes, studies used slightly different ICD

- 9 codes to define 

### 21 specific conditions. In seasonal analyses, stronger associations were observed in the 

### 22 warm season or summer months compared to the cold season, particularly for asthma 

### 23 ( Strickland et al., 2010 ; Ito et al., 2007b ) and COPD ( Medina

- Ramon et al., 2006 ) 

### 24 ( Figure 6

- 18 ; Table 6

- 28 ), which is consistent with the conclusions of the 2006 O 3 

### 25 AQCD. There is also continued evidence that children are particularly at greatest risk to 

### 26
O 3 - induced respiratory effects ( Silverman and Ito, 2010 ; Strickland et al., 2010 ; Mar and 

### 27 Koenig, 2009 ; Villeneuve et al., 2007 ; Dales et al., 2006 ) . Of note, the consistent 

### 28
associ ations observed across studies for short

- term O 3 exposure and respiratory

- related 

### 29 hospital admissions and ED visits was not supported by studies that focused on 

### 30 respiratory

- related outpatient or physician visits. These differences could potentially be 

### 31

attr ibuted to the severity of O 3 - induced respiratory effects requiring more immediate 

### 32 treatment or behavioral factors that result in delayed visits to a physician. Although the 

### 33 collective evidence across studies indicates a consistent positive association betw een O 3 

### 34 exposure and respiratory

- related hospital admissions and ED visits, the magnitude of 

### 35

### Draft

– Do Not Cite or Quote 6

- 158 June 2012 these associations may be underestimated due to behavioral modification in response to 

### 1 forecasted air quality ( Neidell and Kinney, 2010 ; Neidell, 2009 ) (Section 4.6.5 ). 

### 2

The studies that examined the potential confounding effects of copollutants found that O 3 

### 3 effect estimates remained relatively robust upon the inclusion of PM (measured using 

### 4 different sampling strategies ranging from every

- day to every

- 6th day) and gaseous 

### 5 pollutants in two

- pollutant models ( Figure 6

- 19 ; Table 6

- 29 ). Additional studies that 

### 6 conducted copollutant analyses, but did not present quantitative results, also support these 

### 7
conclusions ( Strickland et al., 2010 ; Tolbert et al., 2007 ; Medina

- Ramon et al., 2006 )

. 

### 8 Overall, recent studies provide copollutant results that are consistent with the studies 

### 9
evaluated in the 2006 O 3 AQCD [ ( U.S. EPA, 2006b )
, Figure 7

- 12, page 7

- 80 of the 2006 

### 10
O 3 AQCD], which found that O 3 respiratory hospital admissions risk estimates remained 

### 11 robust to the inclusion of PM in copollutant mo dels. 

### 12

Note: Effect estimates are for a 20 ppb increase in 24

- h; 30 ppb increase in 8

- h max; and 40 ppb increase in 1

- h max O 3 concentrations. HA=hospital admission; ED=emergency department. Black=All

- year analysis; Red=Summer only analysis; Blue=Winter only analysis.

a Wheeze used as indicator of lower respiratory disease.

b APHENA

- Canada results standardized to approximate IQR of 5.1 ppb for 1

- h max O 3 concentrations.

c Study included 8 cities; but of those 8, only 4 had O 3 data.

d non
- ICU effect estimates.

e The study did not specify the lag day of the summer season estimate.


### Figure 6

- 1 8 Percent increase in respiratory

- related hospital admission and ED visits in studies that presented all

- year and/or seasonal results. Study Wong et al. (2009) Cakmak et al. (2006) Dales et al. (2006) Orazzo et al. (2009)a Katsouyanni et al. (2009)

Darrow et al. (2009) Tolbert et al. (2007) Biggeri et al. (2005)c Katsouyanni et al. (2009)

Stieb et al. (2009) Villeneuve et al. (2007) Strickland et al. (2010) Silverman and Ito (2010)d Ito et al. (2007) Villeneuve et al. (2007) Mar and Koenig (2009) Strickland et al. (2010) Silverman and Ito (2010)d Mar and Koenig (2009) Ito et al. (2007) Villeneuve et al. (2007) Strickland et al. (2010) Wong et al. (2009) Stieb et al. (2009) Yang et al. (2006) Medina

- Ramon et al. (2006) Stieb et al. (2009)e Medina

- Ramon et al. (2006)

Zanobetti and Schwartz (2006) Medina

- Ramon et al. (2006) Location Hong Kong 10 Canadian cities 11 Canadian cities

6 Italian cities APHENA

- Europe APHENA

- U.S. APHENA

- Canada APHENA

- Canada Atlanta Atlanta 8 Italian cities APHENA

- Europe APHENA

- U.S. APHENA

- Canada APHENA

- Canada
7 Canadian Cities

Alberta, CAN

Atlanta New York New York Alberta, CAN Seattle, WA

Atlanta New York Seattle, WA New York Alberta, CAN

Atlanta Hong Kong 7 Canadian Cities

Vancouver 36 U.S. cities 7 Canadian Cities

36 U.S. cities 36 U.S. cities

Boston 36 U.S. cities 36 U.S. cities 36 U.S. cities Age
All All 0

- 27 days

0

- 2 65+ 65+ 65+ 65+ All All All 65+ 65+ 65+ 65+
All > 2 Children

All All > 2 18+ Children

6

- 18 <18 All > 2 Children

All All 65+ 65+ All 65+ 65+
65+ 65+ 65+ 65+ Respiratory

Asthma

COPD

Pneumonia ◄ ►

►

►
► ► Lag
0

- 1 1.2 2 0

- 6 0

- 1 0

- 1 DL (0

- 2) DL (0

- 2)b

1 0

- 2 0

- 3 0

- 1 0

- 1 DL (0

- 2) DL (0

- 2)b

2 0

- 2 0

- 2 0

- 1 0

- 1 0

- 2 2 0

- 2 0

- 1 0 0

- 1 0

- 2 0

- 2
0

- 1 2 0

- 3 DL (0

- 1)

NR DL (0

- 1) DL (0

- 1)

0

- 1 DL (0

- 1) DL (0

- 1) DL (0

- 1) Visit Type

HA HA HA ED HA HA HA HA ED ED HA HA HA HA HA
ED ED ED HA ED ED ED ED HA ED ED ED ED
HA ED HA HA ED HA HA
HA HA HA HA

- 25

- 20

- 15

- 10

- 5 0 5 10 15 20 25 30 35 40 % Increase

### Draft

– Do Not Cite or Quote 6

- 159 June 2012 Table 6

- 28 Corresponding Effect Estimates for Figure 6

- 18.

Study * ED Visit or Hospital Admission Location Age Lag Avg Time % Increase (95% CI)

Respiratory

All

- year Wong et al. (2009 ) Hospital Admission Hong Kong All 0

- 1 8

- h max 3.58 (1.90, 5.29)

Cakmak et al. (2006b ) Hospital Admission 10 Canadian cities All 1.2 24

- h avg 4.38 (2.19, 6.46)

Dales et al. (2006 ) Hospital Admission 11 Canadian cities 0

- 27 days 2 24

- h avg 5.41 (2.88, 7.96)

Orazzo et al. (2009 ) a ED Visit 6 Italian cities 0

- 2 0

- 6 8

- h max
- 3.34 (

- 11.2, 5.28) Katsouyanni et al. (2009 ) Hospital Admission APHENA

- europe 65+ 0

- 1 1

- h max 1.58 (

- 1.71, 4.15)

APHENA

- U.S. 65+ 0

- 1 1

- h max 2.38 (0.00, 4.89)

APHENA

- Canada 65+ DL(0

- 2) 1

- h max 20.4 (4.07, 40.2)

APHENA

- Canada 65+ DL(0

- 2) b 1

- h max 2.4 (0.51, 4.40)

Warm Darrow et al. (2011a ) ED Visit Atlanta All 1 8

- h max 2.08 (1.25, 2.91) Tolbert et al. (2007 ) ED Visit Atlanta All 0

- 2 8

- h max 3.90 (2.70, 5.20) Biggeri et al. (2005 ) c Hospital Admission 8 Italian cities All 0

- 3 8

- h max 0.06 (

- 5.24, 5.66)

Katsouy anni et al. (2009 ) Hospital Admission APHENA

- europe 65+ 0

- 1 1

- h max 0.24 (

- 3.32, 3.91)

APHENA

- U.S. 65+ 0

- 1 1

- h max 2.14 (

- 0.63, 4.97)

APHENA

- Canada 65+ DL(0

- 2) 1

- h max 37.1 (11.5, 67.5)

APHENA

- Canada 65+ DL(0

- 2) b 1

- h max 4.1 (1.40, 6.80)
Asthma

All

- year Stieb et al. (2009 ) ED Visit 7 Canadian cities All 2 24

- h avg 3.48 (0.33, 6.76) Villeneuve et al. (2007 ) ED Visit Alberta, CAN >2 0

- 2 8

- h max 11.9 (6.8, 17.2) Strickland et al. (2010 ) ED Visit Atlanta Children 0

- 2 8

- h max 6.38 (3.19, 9.57)

Warm

Silverman and Ito (2010 ) d Hospital Admission New York All 0

- 1 8

- h max 12.5 (8.27, 16.7)

Ito et al. (2007b ) ED Visit New York All 0

- 1 8

- h max 16.9 (10.9, 23.4) Villeneuve et al. ( 2007 ) ED Visit Alberta, CAN >2 0

- 2 8

- h max 19.0 (11.9, 28.1) Mar and Koenig (2009 ) ED Visit Seattle, WA 18+ 2 8

- h max 19.1 (3.00, 40.5)

Strickland et al. (2010 ) ED Visit Atlanta Children 0

- 2 8

- h max 8.43 (4.42, 12.7) Silverman and Ito (2010 ) d Hospital Admission New York 6

- 18 0

- 1 8

- h max 28.2 (15.3, 41.5)

Mar and Koenig (2009 ) ED Visit Seattle, WA <18 0 8

- h max 33.1 (3.00, 68.5)

### Draft

– Do Not Cite or Quote 6

- 160 June 2012 Study * ED Visit or Hospital Admission Location Age Lag Avg Time % Increase (95% CI)

Cold Ito et al. (2007b ) ED Visit New York All 0

- 1 8

- h max
- 23.4 (

- 27.3,

- 19.3) Villeneuve et al. (2007 ) ED Visit Alberta, CAN >2 0

- 2 8

- h max 8 .50 (0.00, 17.2) Strickland et al. (2010 ) ED Visit Atlanta Children 0

- 2 8

- h max 4.52 (

- 0.82, 10.1)
COPD

All

- year Stieb et al. (2009 ) ED Visit 7 Canadian cities All 2 24

- h avg 4.03 (

- 0.54, 8.62)

Medina

- Ramon et al. (2006 ) Hospital Admission 36 U.S. cities 65+ 0

- 1 8

- h max 0.24 (

- 0.78, 1.21)

Yang et al. (2005b ) Hospital Admission Vancouver 65+ 0

- 3 24

- h avg 8.80 (

- 12.5, 32.6)

Warm Stieb et al. (2009 ) e ED Visit 7 Canadian cities All NR 24

- h avg 6.76 (0.11, 13.9)

Medina

- Ramon et al. (2006 ) Hospital Admission 36 U.S. cities 65+ 0

- 1 8

- h max 1.63 (0.48, 2.85)

Cold

Medina

- Ramon et al. (2006 ) Hospital Admission 36 U.S. cities 65+ 0

- 1 8

- h max
- 1.85 (

- 3.60,

- 0.06)

Pneumonia

All

- year
Zanobetti and Schwartz (2006 ) Hospital Admission Boston 65+ 0

- 1 24

- h avg
- 5.96 (

- 11.1,

- 1.36)

Medina

- Ramon et al. (2006 ) Hospital Ad mission 36 U.S. cities 65+ 0

- 1 8

- h max 1.81 (

- 0.72, 4.52)

Warm

Medina

- Ramon et al. (2006 ) Hospital Admission 36 U.S. cities 65+ 0

- 1 8

- h max 2.49 (1.57, 3.47)

Cold

Medina

- Ramon et al. (2006 ) Hospital Admission 36 U.S. cities 65+ 0

- 1 8

- h max
- 4.88 (

- 6.59,

- 3.14)

*Includes studies in Figure 6

- 18

.
a Wheeze used as indicator of lower respiratory disease.

b APHENA

- Canada results standardized to approximate IQR of 5.1 ppb for 1

- h max O 3 concentrations.

c Study included 8 cities, but of thos e 8 only 4 had O 3 data.

d Non

- ICU effect estimates.

e The study did not specify the lag day of the summer season estimate.

### Draft

– Do Not Cite or Quote 6

- 161 June 2012 Notes: Effect estimates are for a 20 ppb increase in 24 hours; 30 ppb increase in 8

- h max; and 40 ppb increase in 1

- h max O 3 concentrations.

a Studies that examined hospital admissions,

b A study that examined ED visits,

c Risk estimates from APHENA

- Canada standardized to an approximate IQR of 5.1 ppb for a 1

- h max increase in O 3 concentrations. Black = results from single

- pollutant models; Red = results from copollutant models with PM 10 or PM 2.5 ; Yellow = results from copollutant models with CO; Blue = results from copollutant models with NO 2 ; Green = results from copollutant mod els with SO 2 . 

### Figure 6

- 19 Percent increase in respiratory

- related hospital admissions and ED visits for studies that presented single and copollutant model results. ► ► ► ► ► ◄

◄ Copollutant

PM10

PM10

PM10

PM10

CO
NO2
SO2
PM10

CO
NO2
SO2
PM2.5 Lag

1

c

c

0

- 3

0

- 1 All

- Year

Summer Respiratory

COPD

Asthma Location

APHENA

- U.S.

APHENA

- Europe

APHENA

- Canada

Vancouver

New York Age

65+

65+

All Study

Katsouyanni et al. (2009)a

Yang et al. (2006)a

Ito et al. (2007)b

- 10

- 5 0 5 10 15 20 25 30 % Increase

### Draft

– Do Not Cite or Quote 6

- 162 June 2012 Table 6

- 29 Corresponding effect estimates for Figure 6

- 19

. Study * , a Location Visit Type Age Lag Copollutant % Increase (95% CI)

All

- year: Respiratory Katsouyanni et al. (2009 ) APHENA

- U.S. Hospital Admission 65+ 1 2.62 (0.63, 4.64)

PM 10 2.14 (

- 0.08, 4.40)

APHENA

- europe 2.94 (1.02, 4.89)

PM 10 2.38 (0.08, 4.64)

APHENA

Canada 5.54 (

- 0.94, 12.4) 0.69 (

- 0.12, 1.50)b

PM 10 5.13 (

- 6.62, 18.6)

PM 10 0.64 (

- 0.87, 2.20)b
COPD Yang et al. (2005b ) Vanco uver Hospital Admission 65+ 0

- 3 8.80 (

- 12.5, 32.6)
CO 22.8 (

- 2.14, 50.7)
NO 2 11.1 (

- 10.4, 37.6)
SO 2 13.4 (

- 8.40, 40.2)

PM 10 11.1 (

- 8.40, 37.6)
Summer: Asthma

Ito et al. (2007b ) New York ED All 0

- 1 16.9 (10.9, 23.4)
CO 18.1 (12.1, 24.5)
NO 2 10.2 (4.29, 16.4)
SO 2 13.1 (7.16, 19.5)

PM 2.5 12.7 (6.37, 19.3)

*Studies include in Figure 6

- 19

.
a Averaging times: Katsouyanni et al. (2009 ) = 1

- h max; Yang et al. (2005b ) = 24

- h avg; and Ito et al. (2007b ) = 8

- h max.
b Risk estimates standardized to an approximate IQR of 5.1 ppb for a 1

- h max increase in O 3 concen trations.

To date only a few studies have examined the C

- R relationship between short

- term O 3 

### 1 exposure and respiratory

- related hospital admissions and ED visits. A preliminary 

### 2
examination of the C

- R relationship found no evidence of a deviation from linearity when 

### 3 examining the association between short

- term O 3 exposure and asthma hospital 

### 4
admissions ( Silverman and Ito, 2010 ) . Additionally, an examination of the C

- R 

### 5 relationship for O 3 exposure and pediatric asthma ED visits found no evidence of a 

### 6
threshold with elevated associations with O 3 at concentrations as low as 30 ppb 

### 7 ( Silverman and Ito, 2010 ; Strickland et al., 2010 ) . Ho wever, in both studies there is 

### 8 uncertainty in the shape of the C

- R curve at the lower end of the distribution of O 3 

### 9 concentrations due to the low density of data in this range. 

### 10

### Draft

– Do Not Cite or Quote 6

- 163 June 2012 In totality, building upon the conclusions of the 2006 AQCD, the evidence from recent 

### 1 studies continues to support an association between short

- term O 3 exposure and 

### 2 respiratory

- related hospital admissions and ED visits. Additional evidence also supports 

### 3 stronger associations during the warm season for specific respiratory outcomes s uch as 

### 4
asthma and COPD. 

### 5

6.2.8 Respiratory Mortality

The epidemiologic, controlled human exposure, and toxicological studies discussed 

### 6 within this section (Section 6.2 ) provides evidence for multiple respiratory effects in 

### 7 response to short

- term O 3 exposure. Additionally, the evidence from experimental studies 

### 8 indicates multiple potential pathways of O 3 - induced respiratory effects, which support the 

### 9
contin uum of respiratory effects that could potentially result in respiratory

- related 

### 10 mortality. The 2006 O 3 AQCD found inconsistent evidence for an association between 

### 11
short

- term O 3 exposure and respiratory mortality ( U.S. EPA, 2006b ) . Although some 

### 12 studies reported a strong positive association between O 3 exposure and respiratory 

### 13 mortality, additional studies reported a small association or no association. The majority 

### 14 of recent multicity studies found consistent positive associations between short

- term O 3 

### 15 exposure and respiratory mortality, specifically d uring the summer months. 

### 16

The APHENA study, described earlier in Section 6.2.7.2
, ( Katsouyanni et al., 2009 ) also 

### 17
examined associations between short

- term O 3 exposure and mortality and found 

### 18 consistent positive associations for respiratory mortality in all

- year analyses, except in the 

### 19 Canadian data set for ages ≥ 75, with an increase in the magnitude of associations in 

### 20 analyses restricted to the summer season across data sets and age ranges. Additional 

### 21 multicity studies from the U.S. ( Zanobetti and Schwartz, 2008b ) , Europe ( Samoli et al., 

### 22
2009 ) , Italy ( Stafoggia et al., 2010 ) , and Asia ( Wong et al., 2010 ) that conducted summer 

### 23
season and/or all

- year analyses provide additional support for an association between 

### 24
short

- term O 3 exposure and respiratory mortality ( Figure 6

- 36 ). 

### 25

Of the studies evaluated, only the APHENA study ( Katsouyanni et al., 2009 ) and the 

### 26 Italian multicity study ( Stafoggia et al., 2010 ) conducted an analysis of the potential for 

### 27 copollutant confounding of the O 3 - respiratory mortality relationship. In the APHENA 

### 28 study, specifically the European dataset, focused on the natural spline model with 

### 29
8 df/year (as discussed in Section 6.2.7.2 ) and lag 1 results (as discussed in 

### 30
Section 6.6.2.1 ), respiratory mortality risk estimates were robust to the inclusion of PM 10 

### 31 in copollutant models in all

- year analyses with O 3 respiratory mortality risk estimates 

### 32 increasing in the Canadian and U.S. datasets compared to single

- pollutant model results. 

### 33 In summer season analyses, respiratory O 3 mortality risk estimates were robust in the 

### 34

### Draft

– Do Not Cite or Quote 6

- 164 June 2012 U.S. dataset and attenuated in the European dataset. Similarly, in the Italian multicity 

### 1

stu dy ( Stafoggia et al., 2010 ) , which was limited to the summer season, respiratory 

### 2 mortality risk estimates were attenuated in copollutant models with PM 10 . Based on the 

### 3 APHENA and Italian multicity results, O 3 respiratory mortality risk estimates appear to 

### 4 be moderately to substantially sensitive (e.g., increased or attenuated) to inclusion of 

### 5
PM 10 . However, in the APHENA study, the mostly every

- 6th

- day sampling sched ule for 

### 6
PM 10 in the Canadian and U.S. datasets greatly reduced their sample size and limits the 

### 7 interpretation of these results. 

### 8

6.2.9 Summary and Causal Determination

The 2006 O 3 AQCD concluded that there was clear, consistent evidence of a causal 

### 9 relationship between short

- term O 3 exposure and respiratory effects ( U.S. EPA , 2006b )

. 

### 10 This conclusion was substantiated by evidence from controlled human exposure and 

### 11 toxicological studies indicating a range of respiratory effects in response to short

- term O 3 

### 12 exposure, including pulmonary function decrements and increases in re spiratory 

### 13 symptoms, lung inflammation, lung permeability, and airway hyperresponsiveness. 

### 14 Toxicological studies provided additional evidence for O 3 - induced impairment of host 

### 15 defenses. Combined, these findings from experimental studies provided support for 

### 16 epidemiologic evidence, in which short

- term increases in O 3 concentration were 

### 17 consistently associated with decreases in lung function in populations with increased 

### 18 outdoor exposures, children with asthma, and healthy children; increases in respiratory 

### 19

sy mptoms and asthma medication use in children with asthma; and increases in 

### 20 respiratory

- related hospital admissions and asthma

- related ED visits. Short

- term 

### 21
increases in ambient O 3 concentration also were consistently associated with increases in 

### 22
all

- cause and cardiopulmonary mortality; however, the contribution of respiratory causes 

### 23 to these findings was uncertain. 

### 24

Building on the large body of evidence presented in the 2006 O 3 AQCD, recent studies 

### 25 support associations between short

- term O 3 exposure and res piratory effects. Controlled 

### 26 human exposure studies continue to provide the strongest evidence for lung function 

### 27 decrements in young healthy adults over a range of O 3 concentrations. Studies previously 

### 28 reported mean O 3 - induced FEV 1 decrements of 6

- 8% at 80 ppb O 3 ( Adams, 2006a
, 

### 29
2003a ; McDonnell et al., 1991 ; Horstman et al., 1990 ) , and recent evidence add itionally 

### 30
indicates mean FEV 1 decrements of 6% at 70 ppb O 3 ( Schelegle et al., 2009 ) and 2

- 3% at 

### 31
60 ppb O 3 ( Kim et al., 2011 ; Brown et al., 2008 ; Adams, 2006a ) (Section 6.2.1.1 ). In 

### 32 healthy young adults, O 3 - induced decrements in FEV 1 do not appear to depend on sex 

### 33 ( Hazucha et al., 2003 ) , body surface area or height ( McDonnel l et al., 1997 ) , lung size or 

### 34
baseline FVC ( Messineo and Ad ams, 1990 ) . There is limited evidence that blacks may 

### 35

### Draft

– Do Not Cite or Quote 6

- 165 June 2012 experience greater O 3 - induced decrements in FEV 1 than do age

- matched whites ( Que et 

### 1 al., 2011 ; Se al et al., 1993 ) . Healthy children experience similar spirometric responses 

### 2 but lesser symptoms from O 3 exposure relative to young adults ( McDonnell et al., 

### 3
1985a ) . On average, spirometric and symptom responses to O 3 exposure appear to decline 

### 4 with increasing age beyond about 18 years of a ge ( McDonnell et al., 1999b ; Seal et al., 

### 5
1996 ) . There is also a tendency for slightly increased spirometric responses in mild 

### 6
asthmatics and al lergic rhinitics relative to healthy young adults ( Jorres et al., 1996 )

. 

### 7 Spirometric responses in asthmatics appear to be affected by baseline lung function, 

### 8 i.e., responses increase with disease severity ( Horstman et al., 1995 )

. 

### 9

Available information from controlled human exposure studies on recovery from O 3 

### 10 exposure indicates that an initial phase of recovery in healthy individuals proceeds 

### 11 relatively rapidly, with acute spirometric and symptom responses resolving within about 

### 12
2 to 4 hours ( Folinsbee and Hazucha, 1989 ) . Small residual lung function effects are 

### 13
almost completely resolved within 24 h. Effects of O 3 on the small airways persisting 

### 14

a day following exposure, assessed by persistent decrement in FEF 25

- 75% and altered 

### 15 ventilation distribution, may be due in part to inflammation ( Frank et al., 2001 ; Foster et 

### 16 al., 1997 ) . In more responsive individuals, this recovery in lung function takes longer (as 

### 17 much as 48 hours) to return to baseline. Some cellular responses may not return to 

### 18
baseline levels in humans for more than 10

- 20 days following O 3 exposure ( Devl in et al., 

### 19
1997 ) . Airway hyperresponsiveness and increased epithelial permeability are also 

### 20 observed as late as 24 hours postexposure ( Que et al., 2011 )

. 

### 21

With repeated O 3 exposures over several days, spirometric and symptom responses 

### 22 become attenuated in both healthy individuals and asthmatics, but this attenuation is lost 

### 23 after about a week without exposure ( Gong et al., 1997a ; Folinsbee et al., 1994 ; Kulle et 

### 24 al., 1982 ) . Airway responsiveness also appears to be somewh at attenuated with repeated 

### 25
O 3 exposures in healthy individuals, but becomes increased in individuals with 

### 26 preexisting allergic airway disease ( Gong et al., 1997a ; Folinsbee et al., 1994 ) . Some 

### 27 indicators of pulmonary inflammation are attenuated with repeated O 3 exposures. 

### 28 However, other markers such as epithelial integrity and damage do not show attenuation, 

### 29 suggesting continued tissue damage during r epeated O 3 exposure ( Devlin et al., 1997 )

. 

### 30

Consistent with controlled human exposure study findings, epidemiologic evidence 

### 31 indicates that lung function decrements are related to short

- term inc reases in ambient O 3 

### 32 concentration (Section 6.2.1.2 ). As described in the 1996 and 2006 O 3 AQCDs, the most 

### 33 consistent observations were those in po pulations engaged in outdoor recreation, 

### 34 exercise, or work. Epidemiologic evidence also demonstrates that increases in ambient O 3 

### 35 concentration are associated with decreases in lung function in children with asthma 

### 36 ( Figure 6

- 6 and Figure 6

- 7 and Table 6

- 8 and Table 6

- 9 ) and children without asthma 

### 37

### Draft

– Do Not Cite or Quote 6

- 166 June 2012 ( Figure 6

- 8 and Table 6

- 12 ). Evidence in adults with respiratory disease and healthy 

### 1 adults is inconsistent. In children with asthma, lung function mostly was found to 

### 2 decrease by <1

- 2% per unit increase in O 3 concentration 1 . However, in children with 

### 3 asthma, O 3 - associated lung function decrements were found in conjunction with O 3 - 

### 4 assocated increases in respiratory symptoms ( Just et al., 2002 ; Mortimer et al., 2002 ; 

### 5 Ross et al., 2002 ; Gielen et al., 1997 ; Romieu et al., 1997 ; Thurston et al., 1997 ; Romieu 

### 6 et al., 1996 ) . Biological plausibility for O 3 - asso ciated decrements in lung function in 

### 7 controlled human exposure, epidemiologic, and animal studies is provided by the well



### 8
documented effects of O 3 on activation of bronchial C

- fibers (Section 5.3.2 ). 

### 9

Across disciplines, studies have examined factors that may potentially increase the risk of 

### 10
O 3 - induced decrements in lung function. In the controlled human exposure studies, there 

### 11 is a large degree of in tersubject variability in lung function decrements, symptomatic 

### 12 responses, pulmonary inflammation, airway hyperresponsiveness, and altered epithelial 

### 13 permeability in healthy adults exposed to O 3 ( Que et al., 2011 ; Holz et al., 2005 ; 

### 14 McDonnell, 1996 ) . The magnitude of pulmonary inflammation, airway 

### 15 hyperresponsiveness, and increases in epithelial permeability do not appear to be 

### 16 correlated, nor are these responses to O 3 correlated with changes in lung function, 

### 17 suggesting that different mechanisms may be responsible for these processes ( Que et al., 

### 18
2011 ; Balmes et al., 1997 ; Balmes et al., 1996 ; Aris et al., 1995 ) . However, these 

### 19 responses tend to be reproducible within a given individual over a period of several 

### 20 months indicating differences i n the intrinsic responsiveness of individuals ( Holz et al., 

### 21
2005 ; Hazucha et a l., 2003 ; Holz et al., 1999 ; McDonnell et al., 1985b ) . Numerous 

### 22
reasons for differences in the risk of individuals to O 3 exposure have been reported in the 

### 23 literature. These include dosimetric and mechanistic differences (Section 5.4 ). Further, 

### 24
eviden ce in all three disciplines suggests a role for antioxidant defenses (i.e., vitamin 

### 25 supplementation, genetic variants in oxidative metabolizing enzymes) in modulating 

### 26 respiratory responses to O 3 . The biological plausibility of these findings is provided by 

### 27
the well

- characterized evidence for O 3 exposure leading to the formation of secondary 

### 28 oxidation products that subsequently activate neural reflexes that mediate lung function 

### 29 decrements (Section 5.3.2 ) and that initiate pulmonary inflammation (Section 5.3.3 ). 

### 30

Recent controlled human exposure studies (Section 6.2.3.1 ) and toxicological studies 

### 31 (Section 6.2.3.3 ) also continue to demonstrate lung injury and inflammatory responses 

### 32 upon O 3 exposure. Evidence from more than a hundred toxicological studies clearly 

### 33
indicates that O 3 induces damage and inflammation in the lung, and studies continue to 

### 34 elucidate the mechanistic pathways involved (Section 5.3 ). Though inflammation may 

### 35 resolve, continued cellular damage may alter the st ructure and function of pulmonary 

### 36

1 Effect estimates were standardized to a 40

- ppb increase f or 1

- h max O 3 , a 30

- ppb increase for 8

- h max O 3 , and a 20

- ppb increase for 24

- h avg O 3 .

### Draft

– Do Not Cite or Quote 6

- 167 June 2012 tissues. Recent controlled human studies support previous findings for pulmonary 

### 1
inflammation but demonstrate effects at 60 ppb O 3 , the lowest concentration evaluated. 

### 2 Building on the extensive experimental evidence, recen t epidemiologic studies, most of 

### 3 which were conducted in Mexico City, indicate ambient O 3 - associated increases in 

### 4 pulmonary inflammation in children with asthma. Multiple studies examined and found 

### 5
increases in eNO ( Berhane et al., 2011 ; Khatri et al., 2009 ; Barraza

- Villarre al et al., 

### 6
2008 ) . In subjects with asthma, these O 3 - associated increases in pulmonary inflammation 

### 7 were found concomitantly with O 3 - associated increases in respiratory symptoms ( Khatri 

### 8 et al., 200 9 ; Barraza

- Villarreal et al., 2008 ) . Although more limited in number, 

### 9 epidemiologic studies also found associations with cytokines such as IL

- 6 or IL

- 8 

### 10 ( Barraza

- Villarre al et al., 2008 ; Sienra

- Monge et al., 2004 ) , eosinophils ( Khatri et al., 

### 11
2009 ) , antioxidants ( Sienra

- Monge et al., 2004 ) , and indicators of oxidative stress 

### 12 ( Romieu et al., 2008 ) (Section 6.2.3.2 ). This epidemiologic evidence is coherent with 

### 13
results from controlle d human exposure and toxicological studies that demonstrated an 

### 14 induction or reduction of these same endpoints after O 3 exposure. 

### 15

The evidence for O 3 - induced pulmonary inflammation and airway hyperresponsiveness, 

### 16 largely demonstrated in controlled human ex posure and toxicological studies, provides 

### 17 mechanistic support for O 3 - associated increases in respiratory symptoms observed in both 

### 18 controlled human exposure and epidemiologic studies. Controlled human exposure 

### 19 studies of healthy, young adults demonstrate increases in respiratory symptoms induced 

### 20 by O 3 exposures <80 ppb ( Schelegle et al., 2009 ; Adams, 2006a ) (Section 6.2.1.1 ). 

### 21
Add ing to this evidence, epidemiologic studies find effects in children with asthma. 

### 22 Although the epidemiologic evidence was less consistent in the few available U.S. 

### 23 multicity studies ( O'Connor et al., 2008 ; Schildcrout et al., 2006 ; Mortimer et al., 2002 )
, 

### 24 the weight of evidence, provided by a larger body of single

- city and

- region studies, 

### 25
indicates that short

- term increases in ambient O 3 concentration are as sociated with 

### 26 increases in respiratory symptoms and asthma medication use in children with asthma 

### 27 (Section 6.2.4.1 ). Several epidemiologic studies found associations between ambient O 3 

### 28 concentrations and respiratory symptoms in populations with asthma that also had a high 

### 29 prevalence of allergy (52

- 100%) ( Escamilla

- Nuñez et al., 2008 ; Feo Brito et al., 2007 ; 

### 30 Romieu et al., 2006 ; Just et al., 2002 ; Mortimer et al., 2002 ; Ross et al., 2002 ; Gielen et 

### 31 al., 1997 ) . The strong evidence in populations with asthma and allergy is supported by 

### 32
observations of O 3 - induced inflammation in animal models of allergy ( Section 6.2.3.3 ), 

### 33 and may be explained mechanistically by the action of O 3 to sensitize bronchial smooth 

### 34 muscle to hyperreactivity and thus, potentially act as a primer for subsequent exposure to 

### 35 antigens such as allergens (Section 5.3.5 ). 

### 36

Modification of innate and adaptive immunity is emerging as a mechanistic pathway 

### 37 contributing to the effects of O 3 on asthma and allergic airways disease (Section 5.3.6 ). 

### 38

### Draft

– Do Not Cite or Quote 6

- 168 June 2012 While the majority of evidence comes from animal studies, controlled human exposure 

### 1 studies have found differences between asthmatics and healthy controls in O 3 - mediated 

### 2 innate and adaptive immune responses (Secti on 5.4.2.2 ), suggesting that these pathways 

### 3 may be relevant to humans and may lead to the induction and exacerbation of asthma 

### 4 ( Alexis et al., 2010 ; Hernandez e t al., 2010 ; Alexis et al., 2009 ; Bosson et al., 2003 )

. 

### 5

The subclinical and overt respiratory effects observed across disciplines, as described 

### 6 above, collectively provide support for epidemiologic studies that demonstrate 

### 7 consistently positive associations between sho rt

- term O 3 exposure and respiratory

- related 

### 8 hospital admissions and ED visits (Section 6.2.7 ). Consistent with evidence presented in 

### 9
the 2006 O 3 AQC D, recent multicity studies and a multicontinent study (i.e., APHENA) 

### 10 ( Katsouyanni et al., 2009 ) found risk estimates ranging from an approximate 1.6 to 5.4% 

### 11 increase in all respiratory

- related hospital admissions and ED visits in all

- year analyses 

### 12
for a unit increase in ambient O 3 concentration (as described in Section 2.1 ). Positive 

### 13 associations persisted in analys es restricted to the summer season, but the magnitude 

### 14 varied depending on the study location ( Figure 6

- 18 ). Compared with studies reviewed in 

### 15
the 2006 O 3 AQCD, a larger number of recent studies examined hospital admissions and 

### 16 ED visits for specific respiratory outcomes. Although limited in number, both single

- and 

### 17
multi

- city studies found consistent, positive associations between short

- term O 3 

### 18

exposures and asthma and COPD hospital admissions and ED visits, with more limited 

### 19 evidence for pneumonia. Consistent with the conclusions of the 2006 O 3 AQCD, in 

### 20 studies that conducted seasonal analyses, risk estimates were elevated in the warm season 

### 21 compared to cold season or all

- season analyses, specifically for asthma and COPD. 

### 22 Although recent studies did not include detailed age

- stratified results, the increased risk 

### 23 of asthma hospital admissions ( Silverman and Ito, 2010 ; Strickland et al., 2010 ; Dales et 

### 24 al., 2006 ) observed for children strengthens the conclusion from the 2006 O 3 AQCD that 

### 25 children are potentially at increased risk of O 3 - induced respiratory effects ( U.S. EPA, 

### 26
2006b ) . Although the C

- R relationship has not been ext ensively examined, preliminary 

### 27
examinations found no evidence of a threshold between short

- term O 3 exposure and 

### 28 asthma hospital admissions and pediatric asthma ED visits, with uncertainty in the shape 

### 29
of the C

- R curve at the lower limit of ambient concentr ations in the U.S. ( Silverman and 

### 30 Ito, 2010 ; Strickland et al., 2010 )

. 

### 31

Recent evidence extends the potential range of well

- established O 3 - associated respiratory 

### 32 effects by demonstrating associations between short

- term ambient O 3 exposure and 

### 33 respiratory

- related mortality. In all

- year analyses, a multicontinent (APHENA) and 

### 34 multicity (PAPA) study found consistent, positive associations with respiratory mortality 

### 35 with evidence of an increase in the magnitude of associations in analyses restricted to the 

### 36 summer months. Further, a dditional multicity studies conducted in the U.S. and Europe 

### 37

### Draft

– Do Not Cite or Quote 6

- 169 June 2012 provide evidence supporting stronger O 3 - respiratory mortality associations during the 

### 1 summer season (Section 6.2.8 ). 

### 2

Several studies of respiratory morbidity and mortality evaluated the potential 

### 3 confounding effects of copollutants, in particular, PM 10 , PM 2.5 , or NO 2 . In most cases, 

### 4
effect estimates remained robust to the inclusion of copollutants. In some studies of lung 

### 5 function and respiratory symptoms, larger effects were estimated for O 3 when 

### 6 copollutants were added to models. Ozone effect estimates for respiratory

- related hospital 

### 7 admissions and ED visits remained relatively robus t upon the inclusion of PM and 

### 8 gaseous pollutants in two

- pollutant models ( Strickland et al., 2010 ; Tolbert et al., 2007 ; 

### 9
Medina

- Ramon et al., 2006 ) . Although copollutant confounding was not extensively 

### 10
examined in studies of cause

- specific mortality, O 3 - respirator y mortality risk estimates 

### 11 remained positive but were moderately to substantially sensitive (e.g., increased or 

### 12 attenuated) to the inclusion of PM 10 in copollutant models ( Stafoggia et al., 2010 ; 

### 13 Katsouyanni et al., 2009 ) . However, interpretation of these results requires caution due to 

### 14
the limited PM datasets used in these studies as a result of the every 3rd

- or 6th

- day PM 

### 15 sampling schedule employed in most cities. Together, these copollutant

- adjusted findings 

### 16 across respiratory endpoints provide support for the independent effects of short

- term 

### 17 exposures to ambient O 3 . 

### 18

Across the respiratory endpoin ts examined in epidemiologic studies, associations were 

### 19 found using several different exposure assessment methods that likely vary in how well 

### 20
ambient O 3 concentrations represent ambient exposures and between

- subject variability 

### 21 in exposures. Evidence clea rly demonstrated O 3 - associated lung function decrements in 

### 22 populations with increased outdoor exposures for whom ambient O 3 concentrations 

### 23 measured on site of outdoor activity and/or at the time of outdoor activity have been more 

### 24 highly correlated and simi lar in magnitude to personal O 3 exposures (Section 4.3.3 ). 

### 25 However, associations with respiratory effects also were found with ambient O 3 

### 26

concentrat ions expected to have weaker personal

- ambient relationships, including those 

### 27 measured at home or school, measured at the closest site, averaged from multiple 

### 28 community sites, and measured at a single site. Overall, there was no clear indication that 

### 29 a part icular method of exposure assessment produced stronger findings. 

### 30

An additional consideration in the evaluation of the epidemiologic evidence is the impact 

### 31 of behavioral modifications on observed associations. A study demonstrated that the 

### 32 magnitude of O 3 - a ssociated asthma hospitalizations in Los Angeles, CA was 

### 33 underestimated due to behavioral modification in response to forecasted air quality 

### 34 (Section 4.6.5 ). It is important to note that the study was limited to one metropolitan area 

### 35 and used air quality data for the years 1989

- 1997, when the O 3 concentration that 

### 36 determines the designation of an O 3 action day, was much higher than it is currently. 

### 37

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- 170 June 2012 Both panel and time

- series epidemiologic studies found increases in respiratory effects in 

### 1
association with increases in O 3 concentrations using various exposure metrics 

### 2 (i.e., 24

- h avg, 1

- h max, and 8

- h max O 3 concentrations). However, for respiratory 

### 3

sym ptoms and pulmonary inflammation, a majority of studies examined and found 

### 4
associations with 1

- h max or 8

- h max and 8

- h max or daytime avg O 3 , respectively. 

### 5 Within study comparisons of associations among various exposure metrics with lung 

### 6 function and resp iratory symptoms yielded mixed evidence. Within some studies, larger 

### 7
effects were estimated for shorter O 3 averaging times whereas in other studies, larger 

### 8 effects were estimated for longer averaging times or no difference was found among 

### 9 averaging times. Comparisons in a limited number of time

- series studies indicate rather 

### 10 comparable risk estimates across exposure metrics with some evidence indicating that 

### 11
24

- h avg O 3 was associated with a smaller increase in risk of respiratory ED visits 

### 12 (Section 6.2.7.3 ). Overall, there was no indication that the consistency or magnitude of 

### 13 the observed association was stronger for a particular O 3 exposure metric. In examination 

### 14 of the lag structure of associations, the weight of epidemiologic evidence for the range of 

### 15 respiratory endpoints supports associations with ambient O 3 concentrations lagged 0 to 

### 16
1 day, which is consistent with the O 3 - induced respiratory eff ects observed in controlled 

### 17 human exposure studies. Several studies also found increased respiratory morbidity in 

### 18
association with O 3 concentrations averaged over multiple days (2 to 5 days). Across 

### 19 respiratory endpoints examined in epidemiologic studies, there was not strong evidence 

### 20 that the magnitude of association was larger for any particular lag. 

### 21

In summary, recent studies evaluated since the completion of the 2006 O 3 AQCD support 

### 22 and expand upon the strong body of evidence that indicated a causal relationship between 

### 23
short

- term O 3 exposure and respiratory health effects. Controlled human exposure studies 

### 24
continue to demonstrate O 3 - induced decreases in FEV 1 and pulmona ry inflammation at 

### 25
concentrations as low as 60 ppb. Epidemiologic studies provide evidence that increases in 

### 26
ambient O 3 exposure can result in lung function decrements, increases in respiratory 

### 27 symptoms, and pulmonary inflammation in children with asthma; increases in 

### 28 respiratory

- related hospital admissions and ED visits; and increases in respiratory 

### 29 mortality. Recent toxicological studies demonstrating O 3 - induced inflammation, airway 

### 30 hyperresponsiveness, and impaired lung host defense have continued to sup port the 

### 31 biological plausibility for the O 3 - induced respiratory effects observed in the controlled 

### 32 human exposure and epidemiologic studies. Additionally, recent epidemiologic studies 

### 33 further confirm that respiratory morbidity and mortality associations ar e stronger during 

### 34 the warm/summer months and remain relatively robust after adjustment for copollutants. 

### 35 The recent evidence integrated across toxicological, controlled human exposure, and 

### 36 epidemiologic studies, along with the total body of evidence evalua ted in previous 

### 37 AQCDs, is sufficient to conclude that there is a causal relationship between short



### 38
term O 3 exposure and respiratory health effects. 

### 39

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- 171 June 2012 

## 6.3 Cardiovascular Effects

Overall, there have been a relatively small number of studies that have examined the 

### 1 potential effect of short

- term O 3 exposure on the cardiovascular system. This was 

### 2
reflected in the 1996 O 3 AQCD by the limited discussion on possible O 3 - related 

### 3
cardiovascular effects. The 2006 O 3 AQCD ( U.S. EPA, 2006b ) built upon the limited 

### 4
evidence described in the 1996 O 3 AQCD and further explored the potential r elationship 

### 5
between short

- term O 3 exposure and cardiovascular outcomes. The 2006 O 3 AQCD 

### 6
concluded that “O 3 directly and/or indirectly contributes to cardiovascular

- related 

### 7 morbidity” but added that the body of evidence was limited. This conclusion was bas ed 

### 8 on a controlled human exposure study that included hypertensive adult males, a few 

### 9 epidemiologic studies of physiologic effects, heart rate variability, arrhythmias, 

### 10 myocardial infarctions, and hospital admissions, and toxicological studies of heart rat e, 

### 11 heart rhythm, and blood pressure. 

### 12

6.3.1 Controlled Human Exposure

O 3 reacts rapidly on contact with respiratory system tissue and is not absorbed or 

### 13 transported to extrapulmonary sites to any significa nt degree as such. Controlled human 

### 14 exposure studies discu ssed in the previous AQCDs failed to demonstrate any consistent 

### 15 extrapulmonary effects. Some controlled human exposure studies have attempted to 

### 16 identify specific markers of exposure to O 3 in blood. Buckley et al. (1975 ) reported a 

### 17 28% increase in serum α

- tocopherol and a 26% increase in erythrocyte fragility in healthy 

### 18 males immediately following exposure to 500 ppb O 3 for 2.75 hours with exercise 

### 19 (unspecified activity level). However, in healthy adult males exposed during exercise 

### 20 ( V ̇ E =44 L/min) to 323 ppb O 3 (on average) for 130 min on 3 consecutive days, Foster et 

### 21 al. (1996 ) found a 12% reduction in serum α

- tocopherol 20 hours after the third day of O 3 

### 22

exposure. Liu et al. (1999 ); ( 1997 ) used a salicylate metabolite, 2,3, dehydroxybenzoic 

### 23 acid (DHBA), to indicate increased levels of hydroxyl radical which hydroxylates 

### 24 salicylate to DHBA. Increased DHBA levels after exposure to 120 and 400 ppb suggest 

### 25
that O 3 increases production of hydroxyl radical. The levels of DHBA were correlated 

### 26 with changes in spirometry. Interestingly, simultaneous exposure of healthy adults to O 3 

### 27 (120 ppb for 2 hours at rest) and concentrated ambient particles (CAPs) resulted in a 

### 28 diminished systemic IL

- 6 response compared with exposure to CAPs alone ( Urch et al., 

### 29
2010 )

. 

### 30

Gong et al. (1998 ) exposed hypertensive (n = 10) and healthy (n = 6) adult males, 41 to 

### 31
78 years of age, to FA and on the subsequent day to 300 ppb O 3 for 3 hours with 

### 32 intermittent exercise ( V ̇ E = 30 L/min). The overall results did not indicate any major acute 

### 33

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- 172 June 2012 cardiovascular effects of O 3 in either the hypertensive individuals or healthy controls. 

### 1 Statistically significa nt O 3 effects for both groups combined were increases in heart rate, 

### 2

rate

- pressure product, and the alveolar

- to

- arterial PO 2 gradient, suggesting that impaired 

### 3 gas exchange was being compensated for by increased myocardial work. The mechanism 

### 4 for the decrease in arterial oxygen tension in the Gong et al. (1998 ) study could be due to 

### 5
an O 3 - induced ventilation

- perfusion mismatch. Gong et al. (1998 ) suggested that by 

### 6 impairing alveolar

- arterial oxygen t ransfer, the O 3 exposure could potentially lead to 

### 7 adverse cardiac events by decreasing oxygen supply to the myocardium. The subjects in 

### 8
the Gong et al. (1998 ) study had sufficient functional reserve so as to not experience 

### 9 significa nt ECG changes or myocardial ischemi a and/or injury. In studies evaluating the 

### 10 exercise performance of healthy adults, no significa nt effect of O 3 on arterial O 2 

### 11
saturation has been observed ( Schelegle and Adams, 1986 )

. 

### 12

Fakhri et al. (2009 ) evaluated changes in HRV among adult volunteers (n = 50; 

### 13
27 ± 7 years) during 2

- hour exposures to PM 2.5 CAPs (127 ± 62 μg/m 3 ) and O 3 

### 14 (114 ± 7 ppb), alone and in combination. High frequency HRV was increased following 

### 15
CAPs

- only (p = 0.046) and O 3 - only (p = 0.051) exposures, but not in combination. The 

### 16 standard deviation of NN intervals and the square root of the mean squared differences of 

### 17 successive NN intervals also showed marginally signi fica nt (0.05< p <0.10) increase due 

### 18
to O 3 but not CAPS. Ten of the subjects in this study were characterized as “mildly” 

### 19 asthmatic, however, asthmatic status was not found to modify these effects. Power et al. 

### 20 (2008 ) also investigated HRV in a small group of mild

- to

- moderate allergic asthmatics 

### 21 (n = 5; mean age = 37 years) exposed for 4 hours during moderate intermittent exercise to 

### 22 FA, carbon and ammonium nitrate particles (313 ± 20 μg/m 3 ), and carbon and ammonium 

### 23
ni trate particles (255 ± 37 μg/m 3 ) + O 3 (200 ppb). Changes in frequency

- domain variables 

### 24 for the particle and particle + O 3 exposures were not statistically significa nt compared 

### 25 with FA. Seemingly in contrast to Fakhri et al. (2009 ) , the standard deviation of NN 

### 26 intervals and the square root of the mean squared differences of successive NN intervals 

### 27
also showed a significa nt (p = 0.01) decrease for both the particle and particle + O 3 

### 28 exposures relative to FA responses. Using a similar protocol, Sivagangabalan et al. 

### 29 (2011 ) concluded that spatial dispersion of cardiac repolarization was most affect ed by 

### 30 the combined pollutant exposure of CAP + O 3 compared to FA in healthy adults. 

### 31

Diastolic blood pressure increased by 2 mmHg following the combined O 3 + CAPs 

### 32 exposure, but was not altered by either O 3 or CAPs alone in the Fakhri et al. (2009 ) study. 

### 33 For a subset of the subjects without asthma in the Fakhri et al. (2009 ) study, Urch et al. 

### 34 (2005 ) previously reported a 6 mmHg increase in diastolic blood pressure following a 

### 35
2

- hour resting exposure to O 3 (120 ppb) + PM 2.5 CAPs (150 μg/m 3 ) in healthy adults 

### 36 (n = 23; 32 ± 10 years), which was statistically different from the 1 mmHg increase seen 

### 37 following FA exposure. Brook et al. (2002 ) found O 3 (120 ppb) + PM 2.5 CAPs (150 

### 38

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- 173 June 2012 μg/m 3 ) in healthy adults (n = 25; 35 ± 10 years) caused brachial artery vasoconstriction. 

### 1 However, minimal change in diastolic blood pressure (0.9 mmHg increase) relative to FA 

### 2 (0.4 mmHg decrease) was observed. More recently, Sivagangabalan et al. (2011 ) 

### 3 observed reported a 4.2 mmHg increase in diastolic blood pressure following a 2

- hour 

### 4 resting exposure to O 3 (110 ppb) + PM 2.5 CAPs (150 μg/m 3 ) in healthy adults (n = 25; 

### 5
27 ± 8 years), which was statistically different from the 1.7 mmHg increase seen 

### 6 following the FA exposure. The CAP exposure alone also caused a 3 mmHg increase in 

### 7 diastolic blood pressure which was significa ntly more than following FA. However, 

### 8
similar to F A, the O 3 exposure alone caused a 1.8 mmHg increase in diastolic blood 

### 9 pressure. Overall, these studies indicate an effect of CAPs and CAP + O 3 , but not O 3 

### 10 alone, on diastolic blood pressure. 

### 11

6.3.2 Epidemiology

The 2006 O 3 AQCD concluded that the “generally lim ited body of evidence is highly 

### 12 suggestive that O 3 directly and/or indirectly contributes to cardiovascular

- related 

### 13 morbidity,” including physiologic effects (e.g., release of platelet activating factor 

### 14 [PAF]), HRV, arrhythmias, and myocardial infarctions, although the available body of 

### 15 evidence reviewed during the 2006 O 3 AQCD does not “fully substantiate links between 

### 16
ambient O 3 exposure and adverse cardiovascular outcomes” ( U.S. EPA, 2006b ) . Since 

### 17 the completion of the 2006 O 3 AQCD an increasing number of studies have examined the 

### 18 relationship between short

- term O 3 exposure and cardiovascular morbidity and mortality. 

### 19 These recent studies, as well as evidence from the previous AQCDs, are presented within 

### 20
this section. 

### 21

6.3.2.1 Arrhythmia

In the 2006 O 3 AQCD, conflicting results were observed when examining the effect of O 3 

### 22

o n arrhythmias ( Dockery et al., 200 5 ; Rich et al., 2005 ) . A study by Dockery et al. (2005 ) 

### 23 reported no association between O 3 concentration and ventricular arrhythmias among 

### 24 patients with implantable cardio verter defibrillators (ICD) living in Boston, MA, 

### 25 although when O 3 concentration was categorized into quintiles, there was weak evidence 

### 26 of an association with increasing O 3 concentration (median O 3 concentration: 22.9 ppb). 

### 27 Rich et al. (2005 ) performed a re

- analysis of this cohort using a case

- crossover design 

### 28 and detected a positive association between O 3 conc entration and ventricular arrhythmias. 

### 29
Recent studies were conducted in various locations and each used a different cardiac 

### 30 episode to define an arrhythmic event and a different time period of exposure, which may 

### 31

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- 174 June 2012 help explain observed differences across st udies. Study

- specific characteristics and air 

### 1 quality data for recent studies are reported in Table 6

- 30

. 

### 2

Table 6

- 30 Characterization of ozone concentrations (in ppb) from studies of arrhythmias.

Study* Location Averaging Time Mean Concentration (Standard Deviation) Upper Range of Concentration
Metzger et al. (2007 ) Atlanta, GA 8

- h max Summer only 53.9 (23) Max: 148

Rich et al. (2006b ) Boston, MA 1

- h 22.2* 75th: 33 Max: 119.5

24

- h 22.6* 75th: 30.9 Max: 77.5 Rich et al. (2006a ) St. Louis, MO 24

- h 21* 75th: 31 Anderson et al. (2010 ) L ondon, England 8

- h max 8.08 75th: 11.5 ( Sarnat et al., 2006b ) Steubenville, OH 24

- h Summer and Fall only 21.8 (12.6) 75th: 28.5 Max: 74.8

5 days 22.2 (9.1) 75th: 29.1 Max: 44 Note: Median presented (information on mean not given); studies presented in order of first appearance in the text of this se ction.

Multiple studies examined O 3 - related effects on individuals with ICDs. A study of 518 

### 3 ICD patients who had at least 1 tachyarrythmia within a 10

- year period (totaling 6,287 

### 4 tachyarrhythmic event

- days; 1993

- 2002) was conducted in Atlanta, Georgia ( Metzger et 

### 5 al., 2007 ) . Tachyarrhythmic events were defined as any ventricular tachyarrhythmic 

### 6 event, any ventricular tachyarrhythmic event that resulted in electrical therapy, and any 

### 7 ventricular tachyarrhythmic event that resulted in defibrillation. In the primary analysis, 

### 8
no evidence of an association was observed for a 30 ppb increase in 8

- h max O 3 

### 9 concentrations and tachyarrhythmic events (OR : 1.00 [95% CI: 0.92, 1.08]; lag 0). 

### 10
Season

- specific as well as several sensitivity analyses (including the use of an 

### 11 unconstrained distributed lag model [lags 0

- 6]) were conducted resulting in similar null 

### 12
associations. 

### 13

In a case

- crossover analysis, a pop ulation of ICD patients in Boston, previously examined 

### 14 by ( Rich et al., 2005 ) was used to assess the association between a ir pollution and 

### 15 paroxysmal atrial fibrillation (PAF) episodes ( Rich et al., 2006b ) . In addition to 

### 16 ventricular arrhythmias, ICD de vices may also detect supraventricular arrhythmias, of 

### 17 which atrial fibrillation is the most common. Although atrial fibrillation is generally not 

### 18 considered lethal, it has been associated with increased premature mortality as well as 

### 19 hospitalization and s troke. Ninety

- one electrophysiologist

- confirmed episodes of PAF 

### 20

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– Do Not Cite or Quote 6

- 175 June 2012 were ascertained among 29 patients. An association (OR: 3.86 [95% CI: 1.44, 10.28] per 

### 1
40 ppb increase in 1

- h max O 3 concentrations) was observed between increases in O 3 

### 2 concentration during t he concurrent hour (lag 0

- h) and PAF episodes. The estimated OR 

### 3
for the 24

- hour moving average concentration was elevated (OR: 1.81 [95% CI: 0.86, 

### 4 3.83] per 20 ppb), but weaker than the estimate for the shorter exposure window. The 

### 5
association between PAF and O 3 concentration in the concurrent hour during the cold 

### 6 months was comparable to that during the warm months. In addition, no evidence of a 

### 7 deviation from linearity between O 3 concentration and the log odds of PAF was observed. 

### 8 Authors report that the difference between O 3 concentration and observed effect between 

### 9 this study (PAF and 1

- hour O 3 ) and their previous study (ventricular arrhythmias and 

### 10
24

- hour moving average O 3 ) ( Rich et al., 2005 ) suggest a more rapid response to air 

### 11 pollution for PAF ( Rich et al., 2006b )

. 

### 12

In an additional study, Rich et al. (2006a ) employed a case

- crossover design to examine 

### 13 the association between air pollution and 139 confirmed ventricular arrhythmias among 

### 14 56 ICD patients in St Louis, Missouri. The authors observed a positive association with 

### 15
O 3 concentration (OR: 1.17 [95% CI: 0.58, 2.38] per 20 ppb increase in 24

- hour moving 

### 16 avg O 3 concentrations [lags 0

- 23 hours]). Although the authors concluded these results 

### 17
were similar to their results from Boston ( Rich et al., 2005 ) , they postulated that the 

### 18 pollutants responsible for the increased risk in ventricular arrhythmias are different (O 3 

### 19
and PM 2.5 in Boston and sulf ur dioxide in St Louis). 

### 20

A nderson et al. (2010 ) used a case

- crossover framework to assess air pollution and 

### 21 activation of ICDs among patients from all 9 ICD clinics in the London National Health 

### 22 Service hospitals. “Activation” was defined as tachycardias for which the defibrilla tor 

### 23 delivered treatment. Investigators modeled associations using unconstrained distributed 

### 24 lags from 0 to 5 days. The sample consisted of 705 patients with 5,462 activation days 

### 25 (O 3 concentration information was for 543 patients and 4,092 activation days) . Estimates 

### 26
for the association with O 3 concentration were consistently positive, although weak (OR: 

### 27 1.09 [95% CI: 0.76, 1.55] per 30 ppb increase in 8

- h max O 3 concentrations at 0

- 1 day 

### 28 lag; OR: 1.04 [95% CI: 0.60, 1.81] per 30 ppb increase in 8

- h max O 3 concentrations at 

### 29
0

- 5 day lag) ( Anderson et al., 2010 )

. 

### 30

In contrast to arrhythmia studies conducted among ICD patients, Sarnat et al. (2006b ) 

### 31
recruited non

- smoki ng adults (age range: 54

- 90 years) to participate in a study of air 

### 32 pollution and arrhythmias conducted over two 12

- week periods during summer and fall 

### 33 of 2000 in a region characterized by industrial pollution (Steubenville, Ohio). Continuous 

### 34 ECG data acqu ired on a weekly basis over a 30

- minute sampling period were used to 

### 35 assess ectopy, defined as extra cardiac depolarizations within the atria (supraventricular 

### 36 ectopy, SVE) or the ventricles (ventricular ectopy, VE). Increases in the 5

- day moving 

### 37

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– Do Not Cite or Quote 6

- 176 June 2012 average ( days 1

- 5) of O 3 concentration were associated with an increased odds of SVE 

### 1 (OR: 2.17 [95% CI: 0.93, 5.07] per 20 ppb increase in 24

- h avg O 3 concentrations). A 

### 2 weaker association was observed for VE (OR: 1.62 [95% CI: 0.54, 4.90] per 20 ppb 

### 3
increase in 24

- h avg O 3 concentrations). The results of the effect of 5

- day O 3 

### 4
concentration on SVE were robust to the inclusion of SO 4 2

- in the model [OR: 1.62 

### 5 (95% CI: 0.54, 4.90)]. The authors indicate that the strong associations observed at the 

### 6
5

- day moving average s, as compared to shorter time periods, suggests a relatively long



### 7 acting mechanistic pathways, such as inflammation, may have promoted the ectopic beats 

### 8 in this population ( Sarnat et al., 2006b )

. 

### 9

Although many studies report positive associations, collectively, studies of arrhythmias 

### 10 report inconsistent results. This may be due to variation in study populations, length and 

### 11 season of averagi ng time, and outcome under study. 

### 12

6.3.2.2 Heart Rate/Heart Rate Variability

In the 2006 O 3 AQCD, two large population

- based studies of air pollution and HRV were 

### 13
summarized ( Park et al., 2005b ; Liao et al., 2004a ) . In addition, the biological 

### 14
mechanisms an d potential importance of HRV were discussed. Briefly, the study of acute 

### 15 effects of air pollution on cardiac autonomic control is based on the hypothesis that 

### 16 increased air pollution levels may stimulate the autonomic nervous system and lead to an 

### 17
imbalan ce of cardiac autonomic control characterized by sympathetic activation 

### 18 unopposed by parasympathetic control ( U.S. EPA, 2006b ) . Examples of HRV indices 

### 19
include the standard deviation of normal

- to

- normal intervals (SDNN), the square root of 

### 20 the mean of the sum of the squares of differences between adjacent NN interval s (r



### 21 MSSD), high

- frequency power (HF), low

- frequency power (LF), and the LF/HF ratio. 

### 22 Liao et al. (2004a ) examined the ass ociation between air pollution and cardiac autonomic 

### 23 control in the fourth cohort examination (1996

- 1998) of the U.S.

- based Atherosclerosis 

### 24 Risk in Communities Study. A decrease in log

- transformed HF was associated with an 

### 25
increase in O 3 concentration amon g white study participants. Park et al. (2005b ) 

### 26 examined the effects of air pollution on indices of HRV in a population

- based study 

### 27 among men from the Normative Aging Study in Bosto n, Massachusetts. Several 

### 28
associations were observed with O 3 concentration and HRV outcomes. A reduction in LF 

### 29
was associated with increased O 3 concentration, which was robust to inclusion of PM 2.5 . 

### 30
The associations with all HRV indices and O 3 concentratio n were stronger among those 

### 31 with ischemic heart disease and hypertension. In addition to the population

- based studies 

### 32
included in the 2006 O 3 AQCD was a study by Schwartz et al. (2005 ) , who conducted a 

### 33 panel study to assess the relationship between exposure to summertime air pollution and 

### 34
HRV. A weak association of O 3 concentration during the hour immediately preceding the 

### 35

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– Do Not Cite or Quote 6

- 177 June 2012 health measures was observed with r

- MSSD among a study population that consisted of 

### 1 mostly older female part icipants. In summary, these studies suggest that short

- term 

### 2 exposures to ambient O 3 concentrations are predictors of decreased HRV and that the 

### 3 relationship may be stronger among certain subgroups. More recent studies that examined 

### 4
the association between O 3 concentration and HRV are described below. Study

- specific 

### 5
characteristics and O 3 concentrations for these studies are presented in Table 6

- 31

. 

### 6

Table 6

- 31 Characterization of ozone concentrations (in ppb) from studies of heart rate variability.

Study* Location Averaging Time Mean Conce ntration (Standard Deviation) Upper Range of Concentration
Park et al. (2007 ) Boston, MA 24

- h Range of 17.0

- 29.1 Park et al. (2008 ) Boston, MA 24

- h 23.4 (13) Baja et al. (2010 ) Bost on, MA 0 lag 10

- h lag 23 (16) 21 (15) Wheeler et al. (2006 ) Atlanta, GA 4

- h
24

- h 18.5 29.4 75th: 22.5

Zanobetti et al. (2010 ) Boston, MA 0.5

- h
2

- h 3

- D
5

- D 20.7* 20.5* 21.9* 22.8* 75th: 30.33 75th: 30.08 75th: 28.33 75th: 29.28 Chan et al. (2005a ) Taipei, Taiwan 1

- h 21.9 (15.4) Max: 114.9 Wu et al. (2010 ) Ta ipei, Taiwan Working period 24.9 (14.0) Max: 59.2 Ruidavets et al. (2005a ) Toulouse, France 8

- h max 38.3 (14.8) 75th: 46.9 Max: 80.3 Chuang et al. (2007a ) Taipei, Taiwan 24

- h 48

- h
72

- h 28.4 (12.1) 33.3 (8.9) 33.8 (7.1) Max: 49.3 Max: 47.8 Max: 48.3 Chuang et al. (2007b ) Taipei, Taiwan 1

- h 35.1 Max: 192.0

* Note: Median presented (information on mean not given) ; studies presented in order of first appearance in the text of this section.

Several follow

- up examinations of HRV were conducted among the participants of the 

### 7 Normative Aging Study in Boston. A trajectory cluster analysis was used to assess 

### 8 whether pollution originating from different locations had varying relationships with 

### 9
HRV ( Park et al., 2007 ) . Subjects who were examined on days when air parcels 

### 10 originated in the west had the strongest associations with O 3 ; however, the O 3 

### 11
concentration in this cluster was low (24

- h avg, 17.0 ppb) compared to the other clusters 

### 12 (24

- h avg of 21.3

- 29.1 ppb). LF and SDNN decreased with increases in the 4

- hour 

### 13 moving average of O 3 concentration from the west (LF decreased by 51.2% [95% CI: 1.6, 

### 14 75.9%] and SDNN decre ased by 28.2% [95% CI:

- 0.5, 48.7%] per 30 ppb increase in 

### 15
4

- h avg O 3 concentrations) ( Park et al., 2007 ) . The Boston air mass originating in the 

### 16

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– Do Not Cite or Quote 6

- 178 June 2012 west traveled over Illinois, Indiana, a nd Ohio; states typically characterized by coal



### 1 burning power plants. Due to the low O 3 concentrations observed in the west cluster, the 

### 2 authors hypothesize that O 3 concentration on those days could be capturing the effects of 

### 3 other, secondary and/or trans ported pollutants from the coal belt or that the relationship 

### 4
between ambient O 3 concentration and personal exposure to O 3 is stronger during that 

### 5 period (supported by a comparatively low apparent temperature which could indicate a 

### 6 likelihood to keep windo ws open and reduced air conditioning use) ( Park et al., 2007 )

. 

### 7
A n additional follow

- up evaluation using the Normative Aging Study examined the 

### 8 potential for effect modification by chronic lead (Pb) exposure on the relationship 

### 9 between air pollution and HRV ( Park et al., 2008 ) . Authors observed graded reductions in 

### 10
HF and LF of HRV in relation to O 3 (and sulfate) concentrations across increasing 

### 11 quartiles of tibia and patella lead (HF: percent change 32.3% [95% CI:

- 32.5, 159.3] for 

### 12 the first quartile of tibia Pb and

- 59.1 [95% CI:

- 77.3,

- 26.1] for the fourth quartile of 

### 13 tibia Pb per 3 0 ppb increase in 4

- h avg O 3 concentrations; LF: percent change 8.0% 

### 14 [95% CI:

- 36.9, 84.9] for the first quartile of tibia Pb and

- 59.3 [95% CI:

- 74.6,

- 34.8] for 

### 15 the fourth quartile of tibia Pb per 30 ppb increase in 4

- h avg O 3 concentrations). In 

### 16
additio n, associations were similar when education and cumulative traffic

- adjusted bone 

### 17 Pb levels were used in analyses. Authors indicate the possibility that O 3 (which has low 

### 18 indoor concentrations) was acting as a proxy for sulfate (correlation coefficient for O 3 

### 19
and sulfate = 0.57). Investigators of a more recent follow

- up to the Normative Aging 

### 20 Study hypothesized that the relationships between short

- term air pollution exposures and 

### 21 ventricular repolarization, as measured by changes in the heart

- rate corrected QT interval 

### 22 (QTc), would be modified by participant characteristics (e.g., obesity, diabetes, smoking 

### 23 history) and genetic susceptibility to oxidative stress ( Baja et al., 2010 ) . No evidence of 

### 24
an association between O 3 concentration (using a quadratic constrained distributed lag 

### 25 model and hourly exposure lag models over a 10

- hour time window preceding the visit) 

### 26 and QTc was reported (change in mean QTc

- 0 .74 [95% CI:

- 3.73, 2.25]); therefore, 

### 27 potential effect modification of personal and genetic characteristics with O 3 concentration 

### 28
was not assessed ( Baja et al., 2010 ) . Collectively, the results from studies that examined 

### 29 the Normative Aging Study cohort found an association between increases in short

- term 

### 30
O 3 concentration and decreases in HRV ( Park et al., 2008 ; Park et al., 2 007 ; Park et al., 

### 31
2005b ) although not consistently in all of the studies ( Baja et al., 2010 ) . Further, observed 

### 32 relationships appear to be stronger among those with ischemic heart disease, 

### 33 hypertension, and elevated bone lead levels, as well as when air masses arrive from the 

### 34 west (the coal belt). However, it is not clear if O 3 concentration is acting as a proxy for 

### 35 other, secondary particle pollutants (such as sulfate) ( Park et al., 2008 ) . In addition, since 

### 36 the Normative Aging Study participants were olde r, predominately white men, results 

### 37 may not be generalizable to the a large proportion of the U.S. population. 

### 38

### Draft

– Do Not Cite or Quote 6

- 179 June 2012 Additional studies of populations not limited to the Normative Aging Study have also 

### 1
examined associations between O 3 exposure and HRV. A panel s tudy among 18 

### 2 individuals with COPD and 12 individuals with recent myocardial infarction (MI) was 

### 3 conducted in Atlanta, Georgia ( Wheeler et al., 2006 ) . HRV was assessed for each 

### 4 participant on 7 days in fall 1999 and/or spring 2000. Ozone concentrations were not 

### 5 associated with HRV (SDNN) among all subjects (percent change of 2.36% [95% CI: 

### 6

- 10.8%, 17.5%] per 30 ppb 4

- hour O 3 increase) or when stratified by disease type 

### 7 (COPD, recent MI, and baseline FEV 1 ) ( Wheeler et al., 2006 )

. 

### 8

HRV and air p ollution was assessed in a panel study among 46 predominately white male 

### 9 patients (study population: 80.4% male, 93.5% white) aged 43

- 75 years in Boston, 

### 10 Massachusetts, with coronary artery disease ( Zanobetti et al., 2010 ) . Up to four home 

### 11 visits were made to assess HRV over the year following the index event. Pollution lags 

### 12 used in analyses ranged between 30 minutes to a few hours and up to 5 days prior to the 

### 13 HRV assessments, calculated from h ourly O 3 measurements averaged over three 

### 14 monitoring sites in Boston. Decreases in r

- MSSD were reported for all averaging times of 

### 15
O 3 concentration (percent change of

- 5.18% [95% CI:

- 7.89,

- 2.30] per 20 ppb of 5

- day 

### 16 moving average of O 3 concentration), bu t no evidence of an association between O 3 

### 17 concentration and HF was observed (quantitative results not provided). In two

- pollutant 

### 18
models with O 3 and either PM 2.5 or BC, O 3 associations remained robust. 

### 19

A few recent studies were conducted outside of the U .S. that examined the relationship 

### 20 between air pollution concentrations and heart rate and HRV ( Wu et al., 2010 ; Chuang et 

### 21 al., 2007b ; Chuang et al., 2007a ; Chan et al., 2005a ; Ruidavets et al., 2005a ) . No 

### 22 associations were reported between O 3 concentration and HRV among CHD pat ients and 

### 23 patients with one or more major CHD risk factors residing in Taipei, Taiwan ( Chan et al., 

### 24
2005a ) . Another study in Taipei, Taiwan examined mail carriers and reported O 3 

### 25 concentration measured using personal monitors. No association was observed between 

### 26
O 3 concentration and the measures of HRV (percent change for SDNN: 0.57 [9 5% CI: 

### 27

- 21.27, 28.46], r

- MSSD:

- 7.10 [95% CI:

- 24.24, 13.92], HF:

- 1.92 [95% CI:

- 23.68, 

### 28 26.02], LF:

- 4.82 [95% CI:

- 25.34, 21.35] per 40 ppb O 3 ) ( Wu et al., 2010 ) . In addition, 

### 29 no consistent relationships were identified between O 3 concentration and resting heart 

### 30 rate among middle

- aged (35

- 64 years) participants residing in Toulouse, France 

### 31 ( Ruidavets et al., 2005a ) . A negative trend was reported for the 3

- day cumulative 

### 32 (lag days 1

- 3) concentration of 8

- h max O 3 with heart rate (p for trend = 0.02); however, 

### 33 the individual odds ratios comparing quintiles of exposure showed no association (OR for 

### 34
O 3 concentraction of 0.93 [95% CI: 0.86, 1.01] for the highest quintile of resting heart rate 

### 35 compared to the lowest). When stratified by current smoking status, non

- smokers had a 

### 36
decreased trend with increased 3

- day cumulative O 3 concentrations b ut none of the 

### 37 quintiles for heart rate were statistically significa nt. A panel study was conducted in 

### 38

### Draft

– Do Not Cite or Quote 6

- 180 June 2012 Taiwan to assess the relationship between air pollutants and inflammation, oxidative 

### 1 stress, blood coagulation, and autonomic dysfunction ( Chuang et al., 2007b ; Chuang et 

### 2 al., 2007a ) . Participants were apparently healthy college students (aged 18

- 25 year) who 

### 3 were living in a university do rmitory in metropolitan Taipei. Health endpoints were 

### 4 measured three times from April to June in 2004 or 2005. Ozone concentration was 

### 5 assessed in statistical models using the average of the 24, 48, and 72 hours before the 

### 6 hour of each blood sampling. Decr eases in HRV (measured as SDNN, r

- MSSD, LF, and 

### 7 HF) were associated with increases in O 3 concentrations in single

- pollutant models 

### 8 (percent change for SDNN:

- 13.45 [95% CI:

- 16.26,

- 10.60], r

- MSSD

- 13.76 [95% CI: 

### 9

- 21.62,

- 5.44], LF

- 9.16 [95% CI:

- 13.29,

- 4.95], HF

- 10.76 [95% CI:

- 18.88,

- 2.32] per 

### 10
20 ppb cumulative 3

- day avg O 3 concentrations) and remained associated with 3

- day O 3 

### 11
concentrations in two

- pollutant models with sulfate. Another study in Taiwan recruited 

### 12
individuals with CHD or at risk for car diovascular disease from outpatient clinics during 

### 13 the study period (two weeks in February) ( Chuang et al., 2007b ) . No association was 

### 14
observed betw een O 3 concentration and HRV measures (SDNN, r

- MSSD, LF, HF) 

### 15 (numerical results not provided in publication). 

### 16

Overall, studies of O 3 concentration and HRV report inconsistent results. Multiple studies 

### 17 conducted in Boston observed positive associations but the authors of many of these 

### 18 studies postulated that O 3 concentration was possibly acting as a proxy for other 

### 19 pollutants. The majority of other studies, both in the U.S. and internationally, report null 

### 20 findings. The inconsistencies observed are further c omplicated by the different HRV 

### 21 measures and averaging times used by the studies. 

### 22

6.3.2.3 Stroke

The 2006 O 3 AQCD did not identify any studies that examined the association between 

### 23
short

- term O 3 exposure and stroke. However, recent studies have attempted to examine 

### 24 this relationship. Lisabeth et al. (2008 ) used a time

- series approach to assess the 

### 25 relationship between daily counts of ischemic stroke and transient ischemic attack (TIA) 

### 26
with O 3 concentrati ons in a southeast Texas community among residents 45 years and 

### 27 older (2001

- 2005; median age of cases, 72 years). The median O 3 concentration (hourly 

### 28 average per 24

- hour time

- period) was 25.6 ppb (IQR 18.1

- 33.8). The associations 

### 29
between same

- day O 3 concen trations and stroke/TIA risk were positive (RR: 1.03 

### 30 [95% CI: 0.96, 1.10] per 20 ppb increase in 24

- h avg O 3 concentrations) and previous

- day 

### 31 (RR: 1.05 [95% CI: 0.99, 1.12] per 20 ppb increase in 24

- h avg O 3 concentrations). 

### 32 Associations were robust to adj ustment for PM 2.5 . 

### 33

### Draft

– Do Not Cite or Quote 6

- 181 June 2012 A case

- crossover design was used in a study conducted in Dijon, France between March 

### 1 1994 and December 2004, among those 40 years of age and older who presented with 

### 2
first

- ever stroke ( Henrotin et al., 2007 ) . The mean O 3 concentration, calculated over 

### 3
8

- hour daytime periods, was 14.95 ppb (IQR: 6

- 22 ppb). No association was observed 

### 4
between O 3 concentration at any of the single

- day lags examined (i.e., 0

- 3 days) and 

### 5 hemorrhagic stroke. However, an association between ischemic stroke occurrence and O 3 

### 6
concentrations with a 1

- day lag was observed (OR: 1.54 [95% CI: 1.14, 2.09] per 30 ppb 

### 7
increas e in 8

- h max O 3 concentrations). The observed association between short

- term O 3 

### 8 exposure and ischemic stroke persisted in two

- pollutant models with PM 10 , SO 2 , NO 2 , or 

### 9 CO. This association was stronger among men (OR: 2.12 [95% CI: 1.36, 3.30] per 30 ppb 

### 10
inc rease in 8

- h max O 3 concentrations) than among women (OR: 1.17 [95% CI: 0.77, 

### 11 1.78] per 30 ppb increase in 8

- h max O 3 concentrations) in single pollutant models. When 

### 12 stroke was examined by subtype among men, an association was observed for ischemic 

### 13
stroke s of large arteries and for transient ischemic attacks, but not for cardioembolic or 

### 14 lacunar ischemic strokes. The subtype analysis was not performed for women. 

### 15 Additionally, for men a linear exposure

- response was observed when O 3 concentration 

### 16

was assesse d based on quintiles (p for trend = 0.01) ( Figure 6

- 20 ). A potential limitation 

### 17 of this study is that 67.4% of the participating men were smokers comp ared to 9.3% of 

### 18
the women. 

### 19

Another case

- crossover study performed in Dijon, France examined the association 

### 20
between O 3 concentration and incidence of fatal and non

- fatal ischemic cerebrovascular 

### 21 events (ICVE) ( Henrotin et al., 2010 ) . Mean 8

- hour O 3 concentration was 19.1 ppb (SD 

### 22
12.2 ppb). A positive association was observed between recurrent ICVE and 8

- h O 3 

### 23

conce ntration with a 3

- day lag (OR: 1.92 [95% CI 1.17, 3.12]), but not for other lags (0, 

### 24 1, 2, 4) or cumulative days (0

- 1, 0

- 2, 1

- 2, 1

- 3). Although some ORs for incident ICVEs 

### 25 were elevated, none were statistically significa nt. Results for associations using t he 

### 26 maximum daily 1

- hour O 3 concentrations were similar to the 8

- hour results but slightly 

### 27 attenuated. ORs were similar in two pollutant models with SO 2 , NO 2 , CO, and PM 10 (data 

### 28 not given). In stratified analyses, the association between 1

- day lagged O 3 con centration 

### 29 and incident and recurrent ICVE was greater among individuals with diabetes or 

### 30 individuals with multiple preexisting vascular conditions. 

### 31

### Draft

– Do Not Cite or Quote 6

- 182 June 2012 Source: Henrotin et al. (2007 )

. 

### Figure 6

- 20 Odds ratio (95% confidence interval) for ischemic stroke by quintiles of ozone exposure

.



### 6.3.2.4 Biomarkers

An increasing number of studies have examined the relationship between air pollution 

### 1 and biomarkers in an attempt to elucidate the biological mechanisms linking air pollution 

### 2 and cardiovascular disease. A wide range of markers assessed as well as different types 

### 3 of study designs and location s chosen make comparisons across studies difficult. 

### 4
Table 6

- 32 provides an overview of the O 3 concentrations reported in each of the studies 

### 5
evaluated

. 

### 6 48-115 33-48 21-32 9-20 0-8 0 0.5

1 1.5

2 2.5

3 3.5

O3 concentration (ppb)Odds ratio (95% CI)

### Draft

– Do Not Cite or Quote 6

- 183 June 2012 Table 6

- 32 Characterization of ozone concentrations (in ppb) from studies of biomarkers.

Study* Location Averaging Time Mean Concentration

(Standard Deviation) Upper Range of Concentration

Liao et al. (2005 ) 3 U.S. counties 8

- h 40 (20)

Th ompson et al. (2010 ) Toronto, Ontario 1

- h / 1 yr 21.94 (15.78)

Rudez et al. (2009 ) Rotterdam, the Netherlands 24

- h 22* 75th: 31.5 Max: 90 Chuang et al. (2007a ) Taipei, Taiwan 24

- h 28.4 (12.1) Max: 49.3

48

- h 33.3 (8.9) Max: 47.8

72

- h 33.8 (7.1) Max: 48.3 Steinvil et al. (2008 ) Tel

- Aviv, Israel 0.5

- h 29.2 (9.7) 75th: 36 Chen et al. (2007a ) Los Angeles and San Francisco, CA 8

- h / 2 weeks 30.8* Max: 47.9

8

- h / 1 mo 28.3* Max: 43.1

Wellenius et al. (2007 ) Boston, MA 1

- h / 24

- h 25.1 (12.9)

Goldberg et al. (2008 ) Montreal, Quebec 24

- h NS

Baccarelli et al. (2007 ) Lombardia, Italy 1

- h 18.3* 75th: 35.1 Max: 202.3 Chuang et al. (2010 ) Taiwan 26.83 (9.7) Max: 62.1

* Note: Median presented (information on mean not given) ; studies presented in order of first appearance in the text of this section.

Hemostasis and coagulation markers

Multiple studies used various markers to examine if associations were present between 

### 1
short

- term O 3 exposure an d hemostasis and coagulation. Some of the markers included in 

### 2 these studies were as follows: fibrinogen, von Willebrand factor (vWF), plasminogen 

### 3 activator fibrinogen inhibitor

- 1 (PAI

- 1), tissue

- type plasminogen activator (tPA), platelet 

### 4 aggregation, and t hrombin generation. 

### 5

A population

- based study in the United States was conducted to assess the relationship 

### 6
between short

- term exposure to air pollution and markers of blood coagulation using the 

### 7 Atherosclerosis Risk in Communities (ARIC) study cohort ( Liao et al., 2005 )

. Significa nt 

### 8
curvilinear associations were observed for O 3 (1 day prior to blood draw) and fibrinogen 

### 9 and vWF (quantitative results not provided for regression models although adjusted 

### 10 means [SE] of vWF were given as 118% [0.79%] for O 3 concentrations <40 ppb, 117% 

### 11 [0.86%] for O 3 concentrations 40

- 70 ppb, and 124% [1.97%] for O 3 concentrations of 

### 12
70 ppb). The association between short

- term O 3 exposure and fibrinogen was more 

### 13

### Draft

– Do Not Cite or Quote 6

- 184 June 2012 pronounced among those with a history of cardiovascular disease (CVD) and was 

### 1
stati stically significa nt among only this subgroup of the population. The curvilinear 

### 2 relationship between concentration and outcome suggested stronger relationships at 

### 3 higher concentrations of O 3 . The authors note that the most pronounced associations 

### 4
occurred when the pollutant concentrations were 2

- 3 standard deviations above the mean. 

### 5 The results from this relatively large

- scale cross

- sectional study suggest weak 

### 6
associations with between short

- term O 3 exposure and increases in fibrinogen (among 

### 7
those with a history of CVD) and vWF. A retrospective repeated measures analysis was 

### 8 performed in Toronto, Canada among adults aged 18

- 40 years (n = 45) between the years 

### 9
of 1999 and 2006 ( Thompson et al., 2010 ) . Single pollutant models were used with 

### 10 moving averages up to 7 days. No evidence of an association w as observed between 

### 11
short

- term O 3 exposure and increases in fibrinogen. 

### 12

A repeated measures study was conducted among 40 healthy individuals living or 

### 13 working in the city center of Rotterdam, the Netherlands to assess the relationship 

### 14 between air pollutio n and markers of hemostatis and coagulation (platelet aggregation, 

### 15 thrombin generation, and fibrinogen) ( Rudez et al., 2009 ) . Each participant provided 

### 16
between 11 and 13 blo od samples throughout a 1

- year period (498 samples on 197 days). 

### 17 Examined lags ranged from 6 hours to 3 days prior to blood sampling. No consistent 

### 18
evidence of an association was observed between O 3 concentration and any of the 

### 19 biomarkers (percent change of max platelet aggregation:

- 6.87 [95% CI:

- 21.46, 7.70] per 

### 20
20 ppb increase in 24

- h avg O 3 concentration at 4

- day average; percent change of 

### 21 endogenous thrombin potential: 0.95 [95% CI:

- 3.05, 4.95 ] per 20 ppb increase in 

### 22
24

- h avg O 3 concentration at 4

- day avg; percent change of fibrinogen:

- 0.57 [95% CI: 

### 23

- 3.05, 2.00] per 20 ppb increase in 24

- h avg O 3 concentration at lag 1

- day). Some 

### 24
associations with O 3 were in the opposite direction to that hypo thesized which may be 

### 25 explained by the negative correlation between O 3 and other pollutants (correlation 

### 26 coefficients ranged from

- 0.4 to

- 0.6). The statistically significa nt inverse effects 

### 27 observed in single

- pollutant models with O 3 were no longer appare nt when PM 10 was 

### 28
included in the model ( Rudez et al., 2009 )

. 

### 29

A panel study in Taiwan measured health endpoints using blood samples from healthy 

### 30 individuals (n = 76) at three times from April to June in 2004 or 2005 ( Chuang et al
., 

### 31
2007a ) . Increases in fibrinogen and PAI

- 1 were associated with increases in O 3 

### 32 concentrations in single

- pollutant models (percent change in fibrinogen: 11.76 [95% CI: 

### 33 4.03, 19.71] per 20 ppb 3

- day cumulative avg O 3 concentration; percent change in PA I

- 1: 

### 34 6.08 [95% CI: 38.91, 84.27] per 20 ppb 3

- day cumulative avg O 3 concentration). These 

### 35
associations were also observed at 1 and 2 day averaging times. Associations between 

### 36
PAI

- 1 and 3

- day O 3 concentrations remained robust in two

- pollutant models with su lfate. 

### 37

### Draft

– Do Not Cite or Quote 6

- 185 June 2012 No association was observed between O 3 concentration and tPA, a fibrinolytic factor 

### 1 (percent change 16.15 [95% CI:

- 4.62, 38.34] per 20 ppb 3

- day avg O 3 concentration). 

### 2

A study in Israel examined the association between pollutant concentrations and 

### 3 fibrinogen among 3659 apparently healthy individuals ( Steinvil et al., 2008 ) . In singl e 

### 4 pollutant models, O 3 was associated with an increase in fibrinogen at a 4

- day lag among 

### 5
men and a same

- day O 3 concentration among women but results for other lags (0 through 

### 6
7 days) were mixed (i.e., some positive and some negative; none statistically si gni fica nt). 

### 7

Inflammatory markers

Potential associations between short

- term exposures to air pollution and inflammatory 

### 8 markers (C

- reactive protein [CRP], white blood cell [WBC] count, albumin, and 

### 9
Interleukin

- 6 [IL

- 6]) were also examined in several studies. 

### 10

The ARIC study cohort, which included men and women aged 45

- 64 years old at the start 

### 11 of the study, was utilized to assess the association between O 3 concentrations and 

### 12 markers of inflammation, albumin and WBC count ( Liao et al., 2005 ) . No association 

### 13
was observ ed between O 3 concentrations and albumin or WBC count. 

### 14

Thompson et al. (2010 ) assessed ambient air pollution exposures and IL

- 6. This 

### 15 retrospective repeated measures analysis was conducted among 45 adults (18

- 40 years of 

### 16 age) in Toronto, Canada between the years of 1999 and 2006. Singl e pollutant models 

### 17 were used to analyze the repeated

- measures data using moving averages up to 7 days. A 

### 18 positive association was observed between IL

- 6 and short

- term 1

- h O 3 exposure with the 

### 19 strongest effects observed for the average of lags 0

- 3 days (qua ntitative results not 

### 20 provided). No association was observed for shorter averaging times (average lags of 

### 21
<1 day). When examined by season using 2

- day moving averages, the association 

### 22
between short

- term O 3 exposure and IL

- 6 was positive during only the spr ing and 

### 23

summer. 

### 24

In Rotterdam, the Netherlands, a repeated measures study of healthy individuals living or 

### 25 working in the city center reported no association between short

- term O 3 exposure and 

### 26
CRP ( Rudez et al., 2009 ) . Each of the 40 participants provided between 11 and 13 blood 

### 27 samples throughout a 1

- year period (498 samples on 197 days). No consistent evidence of 

### 28
an association was observed between O 3 concentration and CRP (percent change:

- 0.48 

### 29 [95% CI:

- 14.05, 13.10] per 20 ppb increase in 24

- h avg O 3 concentration at lag 1

- day). 

### 30 Additionally, no association was observed with 2 or 3 day lags. 

### 31

The relationship between pollutant concentrations and one

- time measures of 

### 32
infla mmatory biomarkers was assessed in sex

- stratified analyses among 3,659 apparently 

### 33

### Draft

– Do Not Cite or Quote 6

- 186 June 2012 healthy individuals in Tel Aviv, Israel ( Steinvil et al., 2008 ) . No evidence of an 

### 1
association was observed between O 3 concentration and CRP or WBC for men and 

### 2

women. 

### 3

A panel study of healthy individuals (n = 76) was conducted in Taiwan to assess the 

### 4
relations hip between air pollutants and inflammation ( Chuang et al., 2007a ) . Health 

### 5 endpoints were measured three times from April to June in 2004 or 2005. Ozone effects 

### 6 were assessed in statistical models using the average of the 24 hours (1 day), 48 hours 

### 7 (2 days), and 72 hours (3 days) before the hour of each blood sampling. Increases in CRP 

### 8
were associated with increases in O 3 concentrations in single

- pollutant models (percent 

### 9 change in CRP: 244.38 [95% CI: 4.54, 585.15] per 20 ppb 3

- day avg O 3 concentration). 

### 10 The association was also observed using a 2

- day cu mulative averaging time, but no 

### 11 association was present with a 1

- day averaging t ime. 

### 12

Oxidative stress markers

A few studies have reported on the relationships between short

- term O 3 exposure and 

### 13
increases in markers of oxidative stress. The association betw een O 3 concentration and 

### 14 markers of lipid peroxidation and antioxidant capacity was examined among 120 

### 15 nonsmoking healthy college students, aged 18

- 22 years, from the University of 

### 16 California, Berkeley (February

- June 2002) ( Chen et al., 2007a ) . By design, students were 

### 17 chosen that had experienced different geographic concentrations of O 3 over their lifetimes 

### 18 and during recent summer vacation in either greater Los Angeles (LA) or the 

### 19
San Francisco Bay Area (SF). Long

- term (based on lifetime residential history) and 

### 20

s horter

- term (based on the moving averages of 8

- h max concentrations 1

- 30 days prior to 

### 21
the day of blood collection) O 3 concentration were estimated (lifetime exposure results 

### 22 are presented in Chapter 7 ). A marker of lipid peroxidation, 8

- isoprostane (8

- iso

- PGF), 

### 23 was assessed. This marker is formed continuously under normal physiological conditions 

### 24 but has been found at elevated concentrations in resp onse to environmental exposures. A 

### 25 marker of overall antioxidant capacity, ferric reducing ability of plasma (FRAP), was also 

### 26
measured. Levels of 8

- iso

- PGF were associated with 2

- week (β = 0.035 

### 27 [pg/mL]/8

- hour ppb O 3 , p = 0.007) and 1

- month (β = 0.031 [pg/ mL]/8

- hour ppb O 3 , 

### 28

p = 0.006) estimated O 3 concentrations. No evidence of association was observed 

### 29
between short

- term O 3 exposure and increases in FRAP. A chamber study performed 

### 30 among a subset of study participants supported the primary study results. The 

### 31
concentrations of 8

- iso

- PGF increased immediately after the 4

- hour controlled O 3 

### 32 exposure ended (p = 0.10). However, levels returned to near baseline by 18 hours without 

### 33 further exposure. The authors note that O 3 was highly correlated with PM 10

- 2.5 and NO 2 in 

### 34 this study population; however, O 3 associations remained robust in copollutant mode ls. 

### 35

### Draft

– Do Not Cite or Quote 6

- 187 June 2012 Using blood samples collected between April and June of 2004 or 2005 in Taiwan, the 

### 1
association between short

- term O 3 exposure and a marker of oxidative stress (i.e., 8

- 

### 2 hydroxy

- 2’

- deoxyguanosine (8

- OHdG)) was studied among healthy individuals (n = 76) 

### 3 ( Chuang et al., 2007a ) . Increases in 8

- OHdG were associated with increases in O 3 

### 4 concentrations in single

- pollutant models (percent change in 8

- OHdG: 2.46 [95% CI: 

### 5 1.01, 3.9 2] per 20 ppb increase in 24

- h avg O 3 ). The association did not persist with 2

- or 

### 6
3

- day cumulative averaging times. 

### 7

Markers of overall cardiovascular health

Multiple studies used markers that assess overall cardiovascular well

- being. Wellenius et 

### 8 al. (2007 ) examined Β

- type natriuretic peptide (BNP), a marker of heart failure, in a 

### 9 repeated

- measures study conducted in Boston among 28 patients with congestive heart 

### 10 failure and impaired systolic function. The authors found no evidence of an association 

### 11
between B NP and short

- term O 3 exposures at lags 0

- 3 days (quantitative results not 

### 12 provided). BNP was chosen because it is directly associated with cardiac hemodynamics 

### 13 and symptom severity among those with heart failure and is considered a marker of 

### 14
functional sta tus. However, the authors conclude that the use of BNP may not be useful 

### 15 in studies of the health effects of ambient air pollutants due to the large amount of within



### 16 person variability in BNP levels observed in this population. 

### 17

The relationship between air pollution and oxygen saturation and pulse rate, markers of 

### 18 physiological well

- being, was examined in a 2

- month panel study among 31 congestive 

### 19 heart failure patients (aged 50

- 85 years) in Montreal, Canada from July 2002 to October 

### 20
2003 ( Goldberg et al., 2008 ) . All participants had limited physical functioning 

### 21 (New York Heart Association Classification ≥ II) and an ejection fraction (the fraction of 

### 22 blood pumped out of the heart per beat) less than or equal to 35% (normal is above 55%). 

### 23 Daily mean O 3 concentrations were calculated based on hourly measures at 10 monitoring 

### 24
stations. There was an inverse association between O 3 concentration (lag

- 0) and oxygen 

### 25 saturation when adjustment was made for temporal trends. In the models incorporating 

### 26 personal covariates and weather factors, the association remained but was not statistically 

### 27 significa nt. The associations of O 3 concentration with a lag of 1 day or a 3

- day mean 

### 28 were not statistically significa nt. No evidence of association was observed between O 3 

### 29 concentration and pulse rate. 

### 30

Total homocysteine (tHcy) is an independent risk factor for vascular disease and 

### 31
measurement of this marker after oral methi onine load is used to identify individuals with 

### 32 mild impairment of homocysteine metabolism. The effects of air pollution on fasting and 

### 33 postmethionine

- load tHcy levels were assessed among 1,213 apparently healthy 

### 34 individuals from Lombardia, Italy from Janu ary 1995 to September 2005 ( Baccarelli et 

### 35

### Draft

– Do Not Cite or Quote 6

- 188 June 2012 al., 2007 ) . A 20

- ppb increase in the 24

- h avg O 3 concentrations was associated with an 

### 1 increase in fasting tHcy (percent change 6.25 [95% CI: 0.84, 11.91]) but no association 

### 2 was observed with postmethionine

- load tHcy (percent change 3.36 [95% CI:

- 1.30, 

### 3 8.39]). In addition, no evidence of an association was observed between 7

- day 

### 4 cumulative averaged O 3 concentrations and tHcy (percent change for fasting tHcy 4.16 

### 5 [95% CI:

- 1.76, 10.42] and percent change for postmethionine

- load tHcy

- 0.65 [95% CI: 

### 6

- 5.66, 4.71] per 20 ppb increase in 24

- h avg O 3 concentrations). No evidence of effect 

### 7 modification by smoking was observed. 

### 8

Blood lipids and glucose metabolism markers

Chuang et al. (2010 ) conducted a population

- based cross

- sectional analysis of data 

### 9 collected on 7,778 participant s during the Taiwanese Survey on Prevalence of 

### 10 Hyperglycemia, Hyperlipidemia, and Hypertension in 2001. Apolipoprotein B (ApoB), 

### 11 the primary apolipoprotein among low

- density lipoproteins, was associated with 3

- day 

### 12 avg O 3 concentration at the p <0.10 level. The 5

- day mean O 3 concentration was 

### 13 associated with an increase in triglycerides at p <0.10. In addition, the 1

- , 3

- , and 5

- day 

### 14
mean O 3 concentrations were associated with increased HbA1c levels (a marker used to 

### 15 monitor the degree of control of glucose m etabolism) at the p <0.05 level. The 5

- day 

### 16
mean O 3 concentration was associated with increased fasting glucose levels (p <0.10). No 

### 17
association was observed between O 3 concentration and ApoA1. 

### 18

6.3.2.5 Myocardial Infarction (MI)

The 2006 O 3 AQCD did not report con sistent results indicating an association between 

### 19
short

- term O 3 exposure and MI. One study reported a positive association between 

### 20 current day O 3 concentration and acute MI, especially among the oldest age group (55 to 

### 21
64 year

- olds) ( Ruidavets et al., 2005b ) . No association was observed in a case

- cr ossover 

### 22 study of O 3 concentration during the surrounding hours and MI ( Peters et al., 2001 ) . Since 

### 23
the 2006 O 3 AQCD, a few recent epidemiologic studies have examined the association 

### 24
between O 3 concentration and MI ( Henrotin et al., 2010 ; Rich et al., 2010 ) , arterial 

### 25
stiffness ( Wu et al., 2010 ) and ST

- segment depression ( Delfino et al., 2011 )

. 

### 26

One of the studies conducted in the U.S. examined hospital admissions for first MI and 

### 27 reported no association with O 3 concentration ( Rich et al., 2010 ) . More details on this 

### 28 study are reported in the section on hospital admissions (Section 6.3.2.7 ). A study 

### 29 performed in Dijon, France examined the association between O 3 concentration and 

### 30
incident and rec urrent MI ( Henrotin et al., 2010 ) . The mean 8

- hour O 3 concentration was 

### 31
19.1 ppb (SD 12.2 ppb). Odds ratios for the association between cumulative O 3 

### 32

### Draft

– Do Not Cite or Quote 6

- 189 June 2012 concentrations and recurrent MIs were elevated but none of the results were statistically 

### 1 significa nt (OR: 1.71 [95% CI: 0.91, 3.20] per 20 ppb increase in 24

- h avg O 3 

### 2 concentration for a cumulative lag of 1

- 3 days). No association was observed for incident 

### 3 MIs. In analyses stratified by vascular risk factors, positive associations were observed 

### 4
between 1

- day lagged O 3 concentration and MIs (incident and recurre nt combined) 

### 5 among those who reported having hypercholesterolaemia (OR: 1.52 [95% CI: 1.08, 2.15] 

### 6 per 20 ppb increase in 24

- h avg O 3 concentration) and a slight inverse association was 

### 7 observed among those who reported not having hypercholesterolaemia (OR: 0.69 

### 8 [95% CI: 0.50, 0.94] per 20 ppb increase in 24

- h avg O 3 concentration). In other stratified 

### 9 analyses combining different vascular factors, only those containing individuals with 

### 10 hypercholesterolaemia demonstrated a positive association; none were inv erse 

### 11
associations. 

### 12

Wu et al. (2010 ) examined mail carriers aged 25

- 46 years and measured exposure to O 3 

### 13
concentrations through personal monitors [mean O 3 24.9 (SD 14.0) ppb]. Ozone 

### 14 concentration was positively associat ed with arterial stiffness (percent change 11.24% 

### 15 [95% CI: 3.67, 19.62] per 40 ppb O 3 ) and was robust to adjustment for ultrafine PM. 

### 16

A study performed in the Los Angeles basin reported on the association between O 3 

### 17
concentration and ST

- segment depression , a measure representing cardiac ischemia 

### 18 ( Delfino et al., 2011 ) . Study participants were nonsmokers, at least 65 years old, had a 

### 19 history of corona ry artery disease, and were living in a retirement community. Study 

### 20 periods included five consecutive days in both July to mid

- October and mid

- October to 

### 21 February. Mean 24

- hour O 3 concentrations were 27.1 ppb (SD 11.5 ppb). No association 

### 22
was observed betw een O 3 concentration and ST

- segment depression of at least 1.0 mm 

### 23 during any of the exposure periods (i.e., 1

- h, 8

- h, 1

- day, 2

- da y avg, 3

- day avg, 

### 24
4

- day avg). 

### 25

6.3.2.6 Blood Pressure

In the 2006 O 3 AQCD, no epidemiologic studies examined O 3 - related effects on bloo d 

### 26 pressure (BP). Recent studies have been conducted to evaluate this relationship and 

### 27 overall the findings are inconsistent. The O 3 concentrations for these studies are listed in 

### 28
Table 6

- 33

. 

### 29

### Draft

– Do Not Cite or Quote 6

- 190 June 2012 Table 6

- 33 Characterization of ozone concentrations (in ppb) from studies of blood pressure.

Study* Location Averaging Time Mean Concentration (Standard Deviation) Upper Range of Concentration
Zanobetti et al. (2004 ) Boston, Massachusetts 1

- h 20

5

- days 24 Delfino et al. (2010b ) Los Angeles, California 24

- h 27.1 (11.5) Max: 60.7

Choi et al. (2007 ) Incheon, South Korea 8

- h (warm season) 26.6 (11.8) 75th: 34.8 Max: 62.4

8

- h (cold season) 17.5 (7.3) 75th: 22.9 Max: 33.9 Chuang et al. (2010 ) Taiwan 26.83 (9.7) Max: 62.1

* Note: Studies presented in order of first appearance in the text of this section.

Zanobetti et al. (2004 ) examined the rela tionship between air pollutants and BP from 

### 1 May 1999 to January 2001 for 631 repeat visits among 62 Boston residents with CVD. In 

### 2 single

- pollutant models, higher resting diastolic blood pressure (DBP) was associated 

### 3
with the 5

- day (0

- 4 days) averages of O 3 concentration (RR: 1.03 [95% CI: 1.00, 1.05] 

### 4 per 20 ppb increase in 24

- hour O 3 concentrations). However, this effect was no longer 

### 5 apparent when PM 2.5 was included in the model (data were not presented) ( Zanobetti et 

### 6 al., 2004 )

. Delfino et al. (2010b ) examined 64 subjects 65 years and older with coronary 

### 7 artery disease, no tobacco smoke exposure, and living in retirement communities in the 

### 8
Los Angeles air basin with hourly (up to 14

- h/day) ambulatory BP monitoring for 5 days 

### 9 during a warm per iod (July

- mid

- October) and 5 days during a cool period (mid

- October



### 10 February). Investigators assessed lags of 1, 4, and 8 hours, 1 day, and up to 9 days before 

### 11 each BP measure; no evidence of an association was observed for O 3 (change in BP 

### 12
associated with a 20 ppb increase in 24

- h avg O 3 concentration was 0.67 [95% CI:

- 1.16, 

### 13 2.51 for systolic BP [SBP] and

- 0.25 [95% CI:

- 1.25, 0.75] for DBP) ( Delfino et al., 

### 14
2010b )

. Choi et al. (2007 ) conducted a cross

- sectional study to investigate the 

### 15 relationship between air pollutants and BP among 10,459 participants of the Inha 

### 16 University Hospital health examination from 2001 to 2003. These individuals had no 

### 17 medical history of cardiovascular disease or hypertension. O 3 concentration was 

### 18
associated with an increase in SBP for 1

- day lag in the warm season and similar effect 

### 19 estimates were observed during the cold season but were not statistically significa nt 

### 20 (quantitative results not provided). Associations between O 3 concentration and DBP were 

### 21 present in the cold season but not the warm season (quantitative results no t provided). 

### 22 Chuang et al. (2010 ) conducted a similar type of study among 7,578 participants of the 

### 23 Taiwanese Survey on Prevalence of Hyperglycemia, Hyperlipidemia, and Hypertension 

### 24 in 2001. Investigators examined 1

- , 3

- , and 5

- day avg O 3 concentrations. An increase in 

### 25

### Draft

– Do Not Cite or Quote 6

- 191 June 2012 DBP was associated with the 3

- day mean O 3 concentration (change in BP for a 20 ppb 

### 1
increase in 24

- h avg O 3 concentration was 0.61 [95% CI: 0.07, 1.14]) ( Chuang et al., 

### 2
2010 ) . Associations were not observed for othe r days or with SBP. 

### 3

6.3.2.7 Hospital Admissions and Emergency Department Visits

Upon evaluating the collective evidence for O 3 - related cardiovascular hospital admissions 

### 4 and emergency department (ED) visits, the 2006 O 3 AQCD concluded that “a few studies 

### 5
observed positive O 3 associations, largely in the warm season. Overall, however, the 

### 6 currently available evidence is inconclusive regarding any association between ambient 

### 7
O 3 exposure on cardiovascular hospitalizations” ( U.S. EPA, 2006b )

. Table 6

- 34 below 

### 8 provides information on the O 3 concentrations reported in each of the recent hospital 

### 9
admission and ED visit studies evaluated. 

### 10

### Draft

– Do Not Cite or Quote 6

- 192 June 2012 Table 6

- 34 Characterization of ozone concentrations (in ppb) from studies of hospital admissions and ED visits.

Study * Location Averaging Time Mean Concentration (Standard Deviation) Upper Range of Concentration
Peel et al. (2007 ) Atlanta, GA 8

- h max

warm season 55.6 (23.8)

Tolbert et al. (2007 ) Atlanta, GA 8

- h max

warm season 53.0 75th: 67.0 Max: 147.5 Katsouyanni et al. (2009 ) 12 Canadian cities 1

- h 6.7

- 8.3* 75 th : 8.4

- 12.4 8 European cities 1

- h 11.0

- 38.1* 75th: 15.3

- 49.4

14 United Statescities 1

- h 34.9

- 60.0* 75th: 46.8

- 68.8

Rich et al. (2010 ) New Jersey 24

- h NR Cakmak et al. (2006a ) 10 Canadian cities 1

- h max 17.4 Stieb et al. (2009 ) 7 Canadian cities 24

- h 18.4 Szyszkowicz (2008 ) Edmonton, Canada 24

- h 18.6 (9.3) Villeneuve et al. (2006a ) Edmonton, Canada 24

- h 17 (9.1) 75th: 23.5

24

- h

warm season 21.8 (8) 75th: 27.0

24

- h cold season 12.2 (7.4) 75th: 17.0

Symons et al. (2006 ) Baltimore, MD 8

- h

warm season 31.0 (20.0) Max: 120.0

Wellenius et al. (2005 ) Allegheny County, PA 24

- h 24.3 (12.2) 75th: 32.0

Zanobetti and Schwartz (2006 ) Boston, MA 24

- h 22.4* 75th: 31.0 Yang (2008 ) Taipei, Taiwan 24

- h 21.0 75th: 26.3 Max: 62.8 Lee et al. (2007 ) Kaohsiung, Taiwan 24

- h 26.5 75th: 35.5 Ma x: 83.0 Chan et al. (2006 ) Taipei, Taiwan 1

- h max 50.9 (26.4) Max: 150.3 Chiu and Yang (2009 ) Taipei, Taiwan 24

- h 23.0 75 th : 28.7 Max: 62.8 Lee et al. (2008a ) Taipei, Taiwan 24

- h 21.0 75 th : 26.4 Max: 62.8 Wong et al. (2009 ) Hong Kong 8

- h 18.5 (11.5) 75 

### th : 25.4
Max: 48.3 Bell et al. (2008 ) Taipei, Taiwan 24

- h 21.4 Max: 53.4 Buadong et al. (2009 ) Bangkok, Thailand 1

- h 14.4 (3.2) Max: 41.9 Lee et al. (2003b ) Seoul, Korea 1

- h max 36.0 (18.6) 75th: 44.9 Azevedo et al. (2011 ) Portugal 1

- h NR Linares and Diaz (2010 ) Madrid,Spain 24

- h 17.4 (8.9) Middleton et al. (2008 ) Nicosia, Cyprus 8

- h max 28.7

- 54.9

### Draft

– Do Not Cite or Quote 6

- 193 June 2012 Study * Location Averaging Time Mean Concentration (Standard Deviation) Upper Range of Concentration
Turner et al. (2007 ) Sydney, Australia 24

- h 28 75th: 33 Ballester et al. (2006 ) 14 Spanish cities 8

- h

warm season 24.2

- 44.3

DePablo et al. (2006 ) Castilla

- Leon, Spain 24

- h 23.2

- 33.6 VonKlot et al. (2005 ) 5 European cities 8 h max

warm season 16.4

- 28.0

Oudin et al. (2010 ) Scania, Sweden 24

- h 30.5 Halonen et al. (2009 ) Helsinki, Finland 8

- h max

warm season 35.7* 75th: 42.1 Max: 79.6 Larrieu et al. (2007 ) 8 French cities 8

- h max

warm season 34.2

- 53.1

Barnett et al. (2006 ) 4 Australian cities 8

- h 19.0

- 28.5 Max: 58.4

- 86.8 Hinwood et al. (2006 ) Perth, Australia 8

- h max 25.9 (6.5) Lanki et al. (2006 ) 5 European cities 8

- h max

warm season 31.7

- 57.2*

Hosseinpoor et al. (2005 ) Tehran, Iran 8

- h max 4.9 (4.8) 75th: 7.2 Max: 99.0 Simpson et al. (2005 ) 4 Australian cities 1

- h max 24.4

- 33.8 Max: 96.0

- 111.5 Dennekamp et al. (2010 ) Melbourne, Australia 24

- h 13.34 75th: 16.93 Silverman et al. (2010 ) New York City, NY 8

- h max 28* 75th: 40

* Notes: Median presented (information on mean not given); NR: Not reported; studies presented in order of first appearance in the text of this section.

Multiple recent studies of O 3 concentration and cardiovascular hospital admissions and 

### 1
ED visits have been conducted in the U.S. and Canada. Peel et al. (2007 ) used a case



### 2 crossover framework (using a time

- stratified approach matching on day of the week in 

### 3 the calendar month of the event) to assess the relationship between air pollutants and 

### 4 cardiovascular disease ED visits among those with and without secondary comorbid 

### 5 conditions (hypertension, diabetes, chronic obstructive pulmonary disease [COPD], 

### 6 congestive heart failure [CHF], and dysrhythmia). Data on over 4 million ED visits from 

### 7 31 hospitals were collected from January 1993 to August 2000. Ozone was moni tored 

### 8 from March to October. This study was a re

- analysis of a time series study conducted to 

### 9 assess the main effects of air pollutants on cardiovascular ED visits in Atlanta ( Tolbert et 

### 10 al., 2007 ; Metzger et al., 2004 ) . In the initial study, no evidence of associations was 

### 11
observed between O 3 concentration and all CVD visits or visits for CVD subgroups, such 

### 12 as dysrhythmia, CHF, ischemic heart disease (IHD), and peripheral vascular and 

### 13 cerebrovascular disease. The relative risk for all CVD visits was 1.01 (95% CI: 0.98, 

### 14 1.04) for a 30 ppb increase in the 3

- day moving avg (lags 0

- 2 days) of 8

- hour O 3 

### 15
concentration ( Metzger et al., 2004 ) . Similar to the initial investigation using a time



### 16 series analysis, no evidence of an association was observed between short

- term O 3 

### 17

### Draft

– Do Not Cite or Quote 6

- 194 June 2012 exposure and CVD visits at lag 0

- 2 among the entire population using the case

- crossover 

### 1 design ( Peel et al., 2007 ) . However, the relationship between O 3 concentration and 

### 2 peripheral and cerebrovascular disease visits was stronger among patients with comorbid 

### 3 COPD (OR: 1.29 [95% CI: 1.05

- 1.59] per 30 ppb, lag 0

- 2 days) as compared to patients 

### 4 without COPD (OR: 1.01 [95% CI: 0.96

- 1.06] per 30 ppb, lag 0

- 2 days). The same 

### 5 research group expanded upon the n umber of Atlanta hospitals providing ED visit data 

### 6 (41 hospitals) as well as the length of the study period (1993

- 2004) ( Tolbert et al., 2007 )

. 

### 7 Again, models a ssessing the health effects of O 3 concentration utilized data collected 

### 8 from March through October. Similar to the results presented by Metzger et al. (2004 ) 

### 9
and Peel et al. (2007 ) among the entire study population, no evidence of associations was 

### 10
observed for O 3 concentration and CVD visits ( Tolbert et al., 2007 )

. 

### 11

Existing multicity studies in North America and Europe were evaluated under a common 

### 12 framework in the Air Pollution and Health: A European and North American Approach 

### 13 (APHENA) study ( Katsouyanni et al., 2009 ) . One component of the study examined the 

### 14 relationship between short

- term O 3 exposure and CVD hospital admissions among 

### 15
individuals 65 years of age and older. The study presented multiple models but this 

### 16 section focuses on the results for the models that used 8 df to account for temporal trends 

### 17 and natural splines (see Section 6.2.7.2 for additional explanation). Across the study 

### 18 locations, no associations were observed between O 3 concentration and CVD hospital 

### 19 admissions at lags 0

- 1, lag 1, or a distributed lag of 0

- 2. Additionally, there was no 

### 20 evidence of an association when restricting the analysi s to the summer months. 

### 21

A study of hospital admissions for MI was performed using a statewide registry from 

### 22 New Jersey between January 2004 and December 2006 ( Rich et al., 2010 ) . Using a case



### 23 crossover design, the association between the previ ous 24

- h O 3 concentration and 

### 24 transmural infarction (n = 1,003) was examined. No association was observed (OR: 0.94 

### 25 [95% CI: 0.79, 1.13] per 20 ppb increase in 24

- h avg O 3 concentration) and this did not 

### 26 change with the inclusion of PM 2.5 in the model. 

### 27

Cakmak et al. (2006a ) investigated the relationship between gaseous air pollutants and 

### 28 cardiac hospitalizations in 10 large Canadian cities using a time

- series approach. A t otal 

### 29 of 316,234 hospital discharge records for primary diagnosis of congestive heart failure, 

### 30 ischemic heart disease, or dysrhythmia were obtained from April 1993 through March 

### 31 2000. Correlations between pollutants varied substantially across cities, which could 

### 32 partially explain discrepancies in effect estimates observed across the cities. In addition, 

### 33 pollutant lags differed across cities; the average lag for O 3 was 2.9 days. The pooled 

### 34
effect estimate for a 20 ppb increase in the daily 1

- h max O 3 concent ration and the 

### 35 percent change in hospitalizations among all 10 cities was 2.3 (95% CI: 0.11, 4.50) in an 

### 36
all

- year analysis. The authors reported no evidence of effect modification by sex, 

### 37

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– Do Not Cite or Quote 6

- 195 June 2012 neighborhood

- level education, or neighborhood

- level income. A simila r multicity time



### 1 series study was conducted using nearly 400,000 ED visits to 14 hospitals in seven 

### 2
Canadian cities from 1992 to 2003 ( Stieb et al., 2009 ) . Primary analy ses considered daily 

### 3
O 3 single day lags of 0

- 2 days; in addition, sub

- daily lags of 3

- h avg concentrations up to 

### 4
12 hours before presentation to the ED were considered. Seasonal variation was assessed 

### 5 by stratifying analyses by warm and cold seasons. No ev idence of associations between 

### 6
short

- term O 3 exposure and CVD ED visits was observed. One negative, statistically 

### 7 significa nt association was reported between a 1

- day lag of O 3 concentration and visits 

### 8 for angina/myocardial infarction. Ozone concentration was negatively correlated with 

### 9 many of the other pollutants, particularly during the cold season. 

### 10

The effect of air pollution on daily ED visits for ischemic stroke (n = 10,881 visits) in 

### 11 Edmonton, Canada was assessed from April 1992 through March 2002 ( Szyszkowicz, 

### 12
2008 ) . A 26.4% (95% CI: 3.16

- 54.5) increase in stroke ED visits was associated with a 

### 13
20 ppb increase in 24

- hour average O 3 concentration at lag 1 among men aged 20

- 

### 14
64 years in the warm season. No ass ociations were present among women or among men 

### 15 age 65 and older. In addition, no associations were observed for the cold season or for 

### 16 other lags (lag 0 or lag 2). A similar investigation over the same time period in 

### 17 Edmonton, Canada, assessed the relatio nship between air pollutants and ED visits for 

### 18 stroke (ischemic stroke, hemorrhagic stroke, and transient ischemic attack) among those 

### 19
65 years of age and older using a case

- crossover framework ( Villeneuve et al., 2006a )

. 

### 20
No e vidence of association was reported for O 3 concentration and stroke hospitalization 

### 21 in single or co

- pollutant models ( Villeneuve et al., 2006a )

. 

### 22

Additional studies in the U.S. reported no evidence of an association between O 3 

### 23 concentrations and ED visits, hospitalizations, or symptoms leading to hospitalization 

### 24 ( Symons et al., 2006 ; Zanobetti and Schwartz, 2006 ; Wellenius et al., 2005 )

. Symons et 

### 25 al. (2006 ) used a case

- crossover framework to assess the relationship between air 

### 26 pollutants and the onset of symptoms (dyspnea) severe enough to lead to hospitalization 

### 27 (through the ED) for congestive heart failure. The study was conducted from April to 

### 28
Decembe r of 2002 in Baltimore, Maryland. Exposures were assigned using 3 index times: 

### 29
8

- hour and 24

- hour periods prior to symptom onset and date of hospital admission. No 

### 30 evidence of association was reported for O 3 concentrations. Although seasonal variation 

### 31

was not assessed, the time frame for the study did not involve an entire year (April to 

### 32 December). Wellenius et al. (2005 ) investigated the association between air poll utants 

### 33 and congestive heart failure hospitalization among Medicare beneficiaries in Pittsburgh, 

### 34 Pennsylvania from 1987 to 1999 utilizing a case

- crossover framework. A total of 55,019 

### 35 admissions from the emergency room with a primary discharge diagnosis of CHF were 

### 36 collected. No evidence of an association was reported for O 3 concentration and CHF 

### 37 hospitalization ( Wellenius et al., 2005 ) . Finally, Zanobetti and Schwartz (2006 ) assessed 

### 38

### Draft

– Do Not Cite or Quote 6

- 196 June 2012 the relationship between air pollutants and hospi tal admissions through the ED for MI 

### 1 and pneumonia among patients aged 65 and older residing in the greater Boston area 

### 2 (1995

- 1999) using a case

- crossover framework with control days in the same month 

### 3 matched on temperature. Pollution exposures were assign ed for the same day and for the 

### 4 mean of the exposure the day of and the day before the admission. Ozone concentration 

### 5
was not associated with MI admissions in all

- year and seasonal analyses. 

### 6

Several recent studies have examined the relationship between ai r pollution and CVD 

### 7 hospital admissions and/or emergency department visits in Asia. Of note, some areas of 

### 8 Asia have a more tropical climate than the U.S. and do not experience similar seasonal 

### 9 changes. In Taiwan, fairly consistent positive associations ha ve been reported for O 3 

### 10 concentration and congestive heart failure hospital admissions (for single

- and 

### 11 copollutant models) in Taipei on warm days ( Yang, 2008 ) and in Kaohsiung ( Lee et al., 

### 12
2007 ) ; cerebrovascular disease ED visits (for lag 0 single

- and two

- pollutant models but 

### 13 not other lags) in Tai pei ( Chan et al., 2 006 ) ; and arrhythmia ED visits in Taipei among 

### 14
those without comorbid conditions ( Chiu et al., 2009 ; Lee et al., 2008a ) and in Taipei on 

### 15 warm days among those with and without comorbid conditions ( Lee et al., 2008a )

. 

### 16 However, one study in Taiwan did not show an association. Bell et al. (2008 ) reported no 

### 17
evidence of an association between O 3 concentration and hospital admissions for 

### 18
ischemic h eart disease or cerebrovascular disease. Studies based in Asia but outside 

### 19 Taiwan were also performed. A Hong Kong

- based investigation ( Wong et al., 2009 ) 

### 20 report ed no consistent evidence of a modifying effect of influenza on the relationship 

### 21
between O 3 concentration and CVD admissions. Among elderly populations in Thailand, 

### 22
O 3 concentration was associated with CVD visits, but this association was not detected 

### 23

amon g younger age groups (15

- 64) ( Buadong et al., 2009 ) . Also, a study performed in 

### 24 Seoul, Korea reported a positive association between O 3 concentration and hospital 

### 25 admissions for ischemic heart disease; the association was slightly greater among those 

### 26
over 64 years of age ( Lee et al., 2003b )

. 

### 27

Positive associations between short

- term O 3 exposure and CVD hospital admissions 

### 28 and/or ED visits have been reported in other areas of the world as well ( Azevedo et al., 

### 29
2011 ; Linares and Diaz, 2010 ; Middleton et al., 2008 ; Turner et al., 2007 ; Ballester et al., 

### 30
2006 ; DePablo et al., 2006 ; VonKlot et al., 2005 ) , although not consistently as some 

### 31 studies reported no association ( Oudin et al., 2010 ; Halonen et al., 2009 ; Larrieu et al., 

### 32
2007 ; Barnett et al., 2006 ; Hinwood et al., 2006 ; Lanki et al., 2006 ; Hosseinpoor et al.
, 

### 33
2005 ; Simpson et al., 2005 )

. 

### 34

A couple of studies ( U.S. and Australia) have examined cardiac arrests where emergency 

### 35 services attempted treatment/resuscitation. No evidence of an association between O 3 

### 36

### Draft

– Do Not Cite or Quote 6

- 197 June 2012 concentration and out

- of

- hospital cardiac arrest was observed ( Dennekamp et al., 2010 ; 

### 1 Silverman et al., 2010 )

. 

### 2

An increasing number of air pollution studies have investigated the relationship between 

### 3
O 3 concentrations and CVD hospital admissions and/or ED visits. As summarized in the 

### 4
2006 O 3 AQCD, some, especially those reporting results stratified by season (or 

### 5 temperature) or comorbid condi tions have reported positive associations. However, even 

### 6 studies performing these stratified analyses are not consistent and the overall evidence 

### 7 remains inconclusive regarding the association between short

- term O 3 exposure and CVD 

### 8 hospital admissions and ED visits. The Hospital Admission (HA) and ED visit studies 

### 9
evaluated in this section are summarized in Figure 6

- 21 through Figure 6

- 25 , which 

### 10 depict the associations for studies in which quantitative data were presented. Table 6

- 35 

### 11 through Table 6

- 39 provide the numerical results displayed in the figures. 

### 12

### Draft

– Do Not Cite or Quote 6

- 198 June 2012 Note: Change in O 3 standardized to 20 ppb for 24

- h avg period, 30 ppb for 8

- h avg period, and 40 ppb for 1

- h avg period (see Section 2.2 ). Ozone concentrations in ppb. Seasons depicted by colors

– black: all year; red: warm season; light blue: cold season. Age groups of study populations were not specified or were adults with the exception of Katsouyanni et al. (2009 )
, Fung et al. (2005 )
, Wong et al. (1999b ) , and Prescott et al. (1998 ) , which included only individuals aged 65+. Studies organized by outcome and season and then listed in descending order of publication date.


### Figure 6

- 21 Effect estimate (95% CI) per increment ppb increase in ozone for over all cardiovascular ED visits or hospital admissions. Reference

Buadong et al. (2009) Katsouyanni et al. (2009) Katsouyanni et al. (2009) Katsouyanni et al. (2009) Middleton et al. (2008) Fung et al. (2005) Ballester et al. (2001) Petroeschevsky et al. (2001) Linn et al. (2000) Atkinson et al. (1999) Wong et al. (1999a) Wong et al. (1999b) Prescott et al. (1998) Poloniecki et al. (1997) Halonen et al. (2009) Katsouyanni et al. (2009) Katsouyanni et al. (2009) Katsouyanni et al. (2009) Larrieu et al. (2007) Peel et al. (2007) Ballester et al. (2006) Chang et al. (2005) Yang et al. (2004) Wong et al. (1999b) Chang et al. (2005) Yang et al. (2004) Wong et al. (1999a) Wong et al. (1999b)

Cakmak et al. (2006) Ballester et al. (2001) Morgan et al. (1998) Larrieu et al. (2007) Ballester et al. (2006) von Klot et al. (2005)

Bell et al. (2008) Chan et al. (2006) Ballester et al. (2001) Wong et al. (1999a) Wong et al. (1999b) Poloniecki et al. (1997) Peel et al. (2007) Wong et al. (1999b) Wong et al. (1999b) Location

Bangkok, Thailand 14 U.S. cities 12 Canadian cities 8 European cities Nicosia, Cyprus Windsor, Canada Valencia, Spain Brisbane, Australia Los Angeles, CA London, England Hong Kong Hong Kong Edinburgh, Scotland London, England Helsinki, Finland 14 U.S. cities 12 Canadian cities 8 European cities 8 French cities Atlanta, GA 14 Spanish cities Taipei, Taiwan Kaohsiung, Taiwan Hong Kong Taipei, Taiwan Kaohsiung, Taiwan Hong Kong Hong Kong

10 Canadian cities Valencia, Spain Sydney, Australia 8 French cities 14 Spanish cities 5 European cities

Taipei, Taiwan Taipei, Taiwan Valencia, Spain Hong Kong Hong Kong London, England Atlanta, GA Hong Kong Hong Kong **Cerebrovascular disease Cardiac disease**  **Cardiovascular disease**

0.70 0.80 0.90 1.00 1.10 1.20 1.30 1.40 1.50

Effect Estimate

### Draft

– Do Not Cite or Quote 6

- 199 June 2012 Table 6

- 35 Effect estimate (95% CI) per increment ppb increase in ozone for overall cardiovascular ED visits or hospital admissions in studies presented in Figure 6

- 21

. Study * Location Outcome Averaging Time Effect Estimate (95% CI) Atkinson et al. (1999 ) London, England Cardiovascular disease 8

- h 1.03 (1.00, 1.05)

Ballester et al. (2006 ) 14 Spanish cities Cardiovascular disease 8

- h warm season 1.04 (1.0 2 , 1.06)

Cardiac disease 8

- h warm season 1.04 (1.01, 1.07) Ballester et al. (2006 ) Valencia, Spain Cardiovascular disease 8

- h 0.94 (0.84, 1.06)

Cardiac disease 8

- h 0.88 (0.75, 1.03)
Cerebrovascular disease 8

- h 0.86 (0.72, 1.04)

Bell et al. (2008 ) Taipei, Taiwan Cerebrovascular disease 24

- h 0.94 (0.87, 1.02)

Buadong et al. (2009 ) Bangkok, Thailand Cardiovascular disease 1

- h 1.01 (1.00, 1.02)

Cakmak et al. (2006a ) 10 Canadian cities Cardiac disease 1

- h max 1.02 (1.00, 1.04)

Chan et al. (2006 ) Taipei, Taiwan Cerebrovascular disease 1

- h max 1.02 (1.01, 1.03)

Chang et al. (2005 ) Taipei, Taiwan Cardiovascular disease 24

- h warm season 1.42 (1.33 , 1.50)

24

- h cold season 1.15 (1.04, 1.27) Fung et al. (2005 ) Windsor, Canada Cardiovascular disease 1

- h 1.02 (0.92, 1.13)

Halonen et al. (2009 ) Helsinki, Finla nd Cardiovascular disease 8

- h max warm season 1.05 (0.96, 1.14)

Katsouyanni et al. (2009 ) 14 U.S. cities Cardiovascular disease 1

- h max 1.01 (0.99, 1.03)

1

- h max warm season 1.00 (0.97, 1.03)

12 Canadian cities Cardiovascular disease 1

- h max 1.00 (0.95, 1.04)

1

- h max warm season 0.98 (0.94, 1.02)

8 European cities Cardiovascular disease 1

- h max 0.99 (0.96, 1.02)

1

- h max warm season 0.98 (0.94, 1.03)

Larrieu et al. (2007 ) 8 French cities Cardiac disease 8

- h max warm season 1.01 (0.98, 1.04)

Linn et al. (2 000 ) Los Angeles, California Cardiovascular disease 24

- h 0.99 (0.98, 1.00)

Mi ddleton et al. (2008 ) Nicosia, Cyprus Cardiovascular disease 8

- h max 1.09 (1.00, 1.18)

### Draft

– Do Not Cite or Quote 6

- 200 June 2012 Study * Location Outcome Averaging Time Effect Estimate (95% CI) Morgan et al. (1998 ) Sydney, Australia Cardiac disease 1

- h max 1.02 (0.99, 1.05)

P eel et al. (2007 ) Atlanta, GA Cardiovascular disease 8

- h warm season 1.00 (0.98, 1.02)

Cerebrovascular disease 8

- h warm season 1.03 (0.97, 1.08)

Petroeschevsky et al. (2001 ) Brisbane, Australia Cardiovascular disease 8

- h 0.96 (0.92, 1.01)

Poloniecki et al. (1997 ) London, England Cardiovascular disease 8

- h 0.97 (0.93, 1.01)

Cerebrovascular disease 8

- h 0.98 (0.95, 1.02)

Prescott et al. (1998 ) Edinburgh, Scotland Cardiovascul ar disease 24

- h 0.89 (0.78, 1.00)

VonKlot et al. (2005 ) 5 European cities Cardiac disease 8

- h max warm season 1.11 (1.00, 1.22)

Wong et al. (1999b ) Hong Kong Cardiovascular disease 24

- h 1.08 (1.03 , 1.13)

24

- h cold season 1.15 (1.04, 1.26)
Cerebrovascular disease 24

- h 0.95 (0.90, 1.01)

Wong et al. (1999a ) Hong Kong Cardiovascular disease 24

- h 1.02 (1.03 , 1.06)

24

- h warm season 1.01 (0.96, 1.06)

24

- h cold season 1.06 (1.02, 1.11)
Cerebrovascular disease 24

- h 0.99 (0.95, 1.04)

24

- h warm season 0.98 (0.90, 1.08)

24

- h cold season 1.02 (0.96, 1.10) Yang et al. (2004 ) Kaohsiung, Taiwan Cardiovascular disease 24

- h warm season 1.33 (1.26 , 1.40)

24

- h cold season 1.05 (0.96, 1.15)
*Studies included in Figure 6

- 21

.. Note: Change in O 3 standardized to 20 ppb for 24

- hour averaging period, 30 ppb for 8

- hour averaging period, and 40 ppb for 1

- hour averaging period (see Section 2.2 ). Ozone concentrations in ppb. Age groups of study populations were not specified or were adults with the exception of Katsouyanni et al. (2009 )
, Fung et al. (2005 )
, Wong et al. (1999a ) , and Prescott et al. (1998 ) , which included only individuals aged 65+. Studies listed in alphabetical order. Warm season defined as: March

- October ( Peel et al., 2007 ) , May

- October ( Ballester et al., 2005 ; Wong et al., 1999a ) , May

- September ( Halonen et al., 2009 ) , April

- September ( Larrieu et al., 2007 ; VonKlot et al., 2005 ) Katsouyanni et al . (2009 ) , ≥ 20°C ( Chang et al., 2005 ) and ≥ 25°C ( Yang et al., 2004 ) . Cold season defined as: November

- April ( Wong et al., 1999a ) , <20°C ( Chang et al., 2005 ) and <25°C ( Yang et al., 2004 ) , December

- March ( Wong et al., 1999b )

### Draft

– Do Not Cite or Quote 6

- 201 June 2012 Note: Change in O 3 standardized to 20 ppb for 24

- hour averaging period, 30 ppb for 8

- hour averaging period, and 40 ppb for 1

- hour averaging period (see Section 2.2 ). Ozone concentrations in ppb. Seasons depicted by colors: black: all year; red: warm season; light blue: cold season. Outcomes were all congestive heart failure, with the exception of Symons et al. (2006 ) , which examined onset of congestive hear t failure symptoms leading to a heart attack. Age groups of study populations were not specified or were adults with the exception of Wellenius et al. (2005 ) and Wong et al. (1999a ) , which included only individuals aged 65+. Studies organized by outcome and season and then listed in descending order of publication date.


### Figure 6

- 22 Effect estimate (95% CI) per increment ppb increase in ozone for congestive heart failure ED visits or hospital admissions. Reference

Stieb et al. (2009)

Wellenius et al. (2005)

Wong et al. (1999a)

Wong et al. (1999b)

Poloniecki et al. (1997)

Yang (2008)

Peel et al. (2007)

Lee et al. (2007)

Symons et al. (2006)

Wong et al. (1999b)

Yang (2008)

Lee et al. (2007)

Wong et al. (1999b) Location

7 Canadian cities

Allegheny county, PA

Hong Kong

Hong Kong

London, England

Taipei, Taiwan

Atlanta, GA

Kaohsiung, Taiwan

Baltimore, MD

Hong Kong

Taipei, Taiwan

Kaohsiung, Taiwan

Hong Kong

0.40 0.60 0.80 1.00 1.20 1.40 1.60 1.80 2.00
Effect Estimate

### Draft

– Do Not Cite or Quote 6

- 202 June 2012 Table 6

- 36 Effect estimate (95% CI) per increment ppb increase in ozone for congestive heart failure ED visits or hospital admissions for studies in Figure 6

- 22

. Study * Location Outcome Averaging Time Effect Estimate (95% CI) Lee et al. (2007 ) Kaohsiung, Taiwan Congestive heart failure 24

- h warm season 1.25 (1.15, 1.36) Congestive heart failure 24

- h cold season 1.24 (1.09, 1.41) Peel et al. (2007 ) Atlanta, GA Congestive heart failure 8

- h warm season 0.94 (0.89, 1.00)

Poloniecki et al. (1997 ) London, England Congestive heart failure 8

- h 0.99 (0.95, 1.03)

Stieb et al. (2009 ) 7 Canadian cities Congestive heart failure 24

- h 1.03 (0.98, 1.07) Symons et al. (2006 ) Baltimore, MD Onset of congestive heart failure symptoms leading to heart attack 8

- h warm season 0.83 (0.49, 1.41)

Wellenius et al. (2005 ) Allegheny county, PA Congestive heart failure 24

- h 0.98 (0.96, 1.01)

Wong et al. (1999a ) Hong Kong Congestive heart failure 24

- h 1.11 (1.04, 1.80)

24

- h warm season 1.09 (0.96, 1.23)

24

- hcold season 1.16 (1.06, 1.27) Yang (2008 ) Taipei, Taiwan Congestive heart failure 24

- h warm season 1.39 (1.27, 1.51) Congestive heart failure 24

- h cold season 0.61 (0.52, 0.73)

Won g et al. (1999b ) Hong Kong Congestive heart failure 24

- h 1.25 (1.11, 1.41)

*Studies include those from Figure 6

- 22

. Note: Change in O 3 standardized to 20 ppb for 24

- hour averaging period, 30 ppb for 8

- hour averaging period, and 40 ppb for 1

- hour averaging period (see Section 2.2 ). Ozone concentrations in ppb. Outcomes were all congestive heart failure, with the exception of Symons et al. (2006 ) , which examined onset of congestive heart failure symptoms leading to a heart attack. Age groups of study populations were not specified or were adults with the exception of Wellenius et al. (2005 ) and Wong et al. (1999a ) , which included only individuals aged 65+. Studies listed in alphabetical order. Warm season defined as: March

- Oct ober ( Peel et al., 2007 ) , April

- November ( Symons et al., 2006 ) , May

October ( Wong et al., 1999a ) ≥ 20°C ( Yang, 2008 ) , and >25°C ( Lee et al., 2007 ) . Cold season defined as: November

- April ( Wong et al., 1999a ) , <20°C ( Yang, 2008 ) , and <25°C ( Lee et al., 2007 )

.

### Draft

– Do Not Cite or Quote 6

- 203 June 2012 Note: Change in O 3 standardized to 20 ppb for 24

- hour averaging period, 30 ppb for 8

- hour averaging period, and 40 ppb for 1

- hour averaging period (see Section 2.2 ). Ozone concentrations in ppb. Seasons depicted by colors: black: all year; red: warm season; light blue: cold season. Age groups of study populations were not specified or were adults with the exception of Wong et al. (1999a ) and Atkinson et al. (1999 ) , which included only individuals aged 65+. Studies organized by outcome and season and then listed in descending order of publication date.


### Figure 6

- 23 Effect est imate (95% CI) per increment ppb increase in ozone for ischemic heart disease, coronary heart disease, myocardial infarction, and angina pectoris ED visits or hospital admissions. Reference

Buadong et al. (2009) Bell et al. (2008) Lee et al. (2003) Atkinson et al. (1999) Wong et al. (1999a) Wong et al. (1999b) Larrieu et al. (2007) Peel et al. (2007) Lee et al. (2003) Wong et al. (1999b) Wong et al. (1999b)

Halonen et al. (2009)

Rich et al. (2010) Buadong et al. (2009) Stieb et al. (2009) Zanobetti et al. (2006) Poloniecki et al. (1997) Lanki et al. (2006) von Klot et al. (2005)

Hosseinpoor et al. (2005) Poloniecki et al. (1997) von Klot et al. (2005) **Angina pectoris Myocardial infarction**  **Ischemic heart disease**

**Coronary heart disease** Location

Bangkok, Thailand Taipei, Taiwan Seoul, Korea London, England Hong Kong Hong Kong 8 French cities Atlanta, GA Seoul, Korea Hong Kong Hong Kong

Helsinki, Finland

New Jersey Bangkok, Thailand 7 Canadian cities Boston, MA London, England 5 European cities 5 European cities

Tehran, Iran London, England 5 European cities

0.5 0.7 0.9 1.1 1.3 1.5 Effect Estimate

### Draft

– Do Not Cite or Quote 6

- 204 June 2012 Table 6

- 37 Effect estimate (9 5% CI) per increment ppb increase in ozone for ischemic heart disease, coronary heart disease, myocardial infarction, and angina pectoris Evisits or hospital admissions for studies presented in Figure 6

- 23.

Study * Location Outcome Averaging Time Effect Estimate (95% CI)

Atkinson et al. (1999 ) London, England Ischemic heart disease 8

- h 0.97 (0.94, 1.01) Bell et al. (2008 ) Taipei, Taiwan Ischemic heart disease 24

- h 1.01 (0.91, 1.12) Buadong et al. (2009 ) Bangkok, Thailand Ischemic heart disease 1

- h 1.00 (0.98, 1.02) Myocardial infarction 1

- h 0.97 (0.94, 1.01) Halonen et al. (2009 ) Helsinki, Finland Coronary heart disease 8

- h max warm season 0.99 (0.79, 1.25)

Hosseinpoor et al. (2005 ) Tehran, Iran Angina 8

- h max 0.80 (0.70, 0.92) Lanki et al. (2006 ) 5 European cities Myocardial infarction 8

- h max warm season 0.96 (0.92, 1.01)

Larrieu et al. (2007 ) 8 French cities Ischemic heart disease 8

- h max warm season 1.02 (0.98, 1.07)

Lee et al. (2003b ) Seoul, Korea Ischemic heart disease 1

- h max 1.07 (1.02, 1.13)

Ischemic heart disease 1

- h max warm season 1.07 (1.00, 1.17)

Peel et al. (2007 ) Atlanta, GA Ischemic heart disease 8

- h warm season 1.00 (0.96, 1.05) Poloniecki et al. (1997 ) London, England Myocardial infarction 8

- h 0.9 8 (0.94, 1.02) Angina 8

- h 0.98 (0.94, 1.03) Rich et al. (2010 ) New Jersey Myocardial infarction 24

- h 0.94 (0.79, 1.13)
Stieb e t al. (2009 ) 7 Canadian cities Myocardial infarction 2

- h 1.00 (0.96, 1.04) VonKlot et al. (2005 ) 5 European cities Myocardial infarction 8

- h max warm season 1.00 (0.83, 1.21)

Angina 8

- h max warm season 1.19 (1.05, 1.35)

Wong et al. (1999a ) Hong Kong Ischemic heart disease 24

- h 1.01 (0.94, 1.06)

24

- h warm season 1.02 (0.94, 1.11)

24

- h cold season 1.02 (0.95, 1.09) Wong et al. (1999b ) Hong Kong Ischemic heart disease 24

- h 1.03 (0.98, 1.08)
Zanobetti and Schwartz (2006 ) Boston, MA Myocardial infarction 24

- h 0.98 (0.92 , 1.03)

*Sudies included from Figure 6

- 23

. Note: Change in O 3 standardized to 20 ppb for 24

- hour averaging period, 30 ppb for 8

- hour averaging period, and 40 ppb for 1

- hour averaging period (see Section 2.2 ). Ozone concentrations in ppb. Age groups of study populations were not specified o r were adults with the exception of Wong et al. (1999a ) and Atkinson et al. (1999 ) , which included only individuals aged 65+. Studies listed in alphabetical order. Warm season defined as: March

- October ( Peel et al., 2007 ) , June

- August ( Lee et al., 2003b ) , May

- September ( Halonen et al., 2009 ) , May

- October ( Buadong et al., 2009 ) , and April

- September ( Larrieu et al., 2007 ; Lanki et al., 2006 ; VonKlot et al., 2005 ) . Cold season defined as: November

- April ( Buadong et al., 2009 )

.

### Draft

– Do Not Cite or Quote 6

- 205 June 2012 Note: Change in O 3 standardized to 20 ppb for 24

- hour averaging period, 30 ppb for 8

- hour averaging period, and 40 ppb for 1

- hour averaging period (see Section 2.2 ). Ozone concentrations in ppb. Seasons depicted by colors: black: all year; red: warm season; light blue: cold season. Age groups of study populations were not specified or were adults with the exception of Villeneuve et al. (2006a ) , which included only individuals aged 65+, and

. Chan et al. (2006 )
, w hich included only individuals aged 50+. St udies organized by outcome and season and then listed in descending order of publication date.


### Figure 6

- 24 Effect estimate (95% CI) per increment ppb increase in ozone for stroke ED visits or hospital admissi ons. Chan et al. (2006) Halonen et al. (2009) Larrieu et al. (2007)

Chan et al. (2006) Villeneuve et al. (2006) Villeneuve et al. (2006) Villeneuve et al. (2006)

Chan et al. (2006) Villeneuve et al. (2006) Villeneuve et al. (2006) Villeneuve et al. (2006)

Villeneuve et al. (2006) Villeneuve et al. (2006) Villeneuve et al. (2006) Reference **All**

**Ischemic**

**Hemorrhagic**

**Transient ischemic** Taipei, Taiwan
Helsinki, Finland

8 French cities

Taipei, Taiwan Edmonton, Canada Edmonton, Canada Edmonton, Canada

Taipei, Taiwan Edmonton, Canada Edmonton, Canada Edmonton, Canada

Edmonton, Canada Edmonton, Canada Edmonton, Canada Location

0.5 0.7 0.9 1.1 1.3 1.5 Effect Estimate

### Draft

– Do Not Cite or Quote 6

- 206 June 2012 Table 6

- 38 Effect estimate (95% CI) per increment ppb increase in ozone for stroke ED visits or hospital admissions for studies presented in Figure 6

- 24.

Study * Location Outcome Averaging Time Effect Estimate (95% CI) Chan et al. (2006 ) Taipei, Taiwan All/non

- specified stoke 1

- h max 1.01 (0.99 ,1.03)

Ischemic stroke 1

- h max 1.03 (0.99, 1.07) Hemorrhagic stroke 1

- h max 0.99 (0.92, 1.06) Halonen et al. (2009 ) Helsinki, Finland All/non

- specified stoke 8

- h max warm season 1.08 (0.83, 1.41)

Larrieu et al. (2007 ) 8 French cities All/non

- specified stoke 8

- h max warm season 0.98 (0.93 , 1.02)

Villeneuve et al. (2006a ) Edmonton, Canada Ischemic stroke 24

- h 1.00 (0.88, 1.13)

Ischemic stroke 24

- h warm season 1.09 (0.91, 1.32)

Ischemic stroke 24

- h cold season 0.98 (0.80, 1.18) Hemorrhagic stroke 24

- h 1.02 (0.87, 1.20) Hemorrhagic stroke 24

- h warm season 1.12 (0.88, 1.43) Hemorrhagic stroke 24

- h cold season 0.97 (0.76, 1.22)

Transient ischemic stroke 24

- h 0.98 (0.87, 1.10)

Transient ischemic stroke 24

- h warm season 0.85 (0.70, 1.01)

Transient ischemic stroke 24

- h cold season 1.11 (0.93, 1.32)

*Studies included from Figure 6

- 24

. . Note: Change in O 3 standardized to 20 ppb for 24

- hour averaging period, 30 ppb for 8

- hour averaging period, and 40 ppb for 1

- hour averaging period (see Section 2.2 ). Ozone concentrations in ppb. Age groups of study populations were not specified or were adults with the exception of Villeneuve et al. (2006a ) , which included only individuals aged 65+, and Chan et al. (2006 ) , which included only individuals aged 50+. Studies listed in alphabetical order. Warm season defined as: May

- September ( Halonen et al., 2009 ) , and April

- September ( Larrieu et al., 2007 ; Villeneuve et al., 2006a ) . Cold season defined as: October

- March ( Villeneuve et al., 2006a )

.

### Draft

– Do Not Cite or Quote 6

- 207 June 2012 Note: Change in O 3 standardized to 20 ppb for 24

- hour averaging period, 30 ppb for 8

- hour averaging period, and 40 ppb for 1

- hour averaging period (see Section 2.2 ). Ozone concentrations in ppb. Seasons depicted by colors: black: all yea r; red: warm season; light blue: cold season. Age groups of study populations were not specified or were adults with the exception of Wong et al. (1999a )
, which included onl y individuals aged 65+. Studies organized by outcome and season and then listed in descending order of publication date.


### Figure 6

- 25 Effect estimate (95% CI) per increment ppb increase in ozone for arrhythmia and dysrhythmia ED visits or hospital admissions. Reference

Stieb et al. (2009)

Peel et al. (2007)

Buadong et al. (2009)

Wong et al. (1999b)

Poloniecki et al. (1997)

Halonen et al. (2009)

Wong et al. (1999b)

Wong et al. (1999b) **Arrhythmia Dysrhythmia**  Location

7 Canadian cities

Atlanta, GA

Bangkok, Thailand

Hong Kong

London, England

Helsinki, Finland

Hong Kong

Hong Kong

0.70 0.80 0.90 1.00 1.10 1.20 1.30 1.40 Effect Estimate

### Draft

– Do Not Cite or Quote 6

- 208 June 2012 Table 6

- 39 Effect estimate (95% CI) per increment ppb increase in ozone for arrhythmia and dysrhythmia ED visits or hospital admissions for studies presented in Figure 6

- 25.

Study Location Outcome Averaging Time Effect Estimate (95% CI)
Buadong et al. (2009 ) Bangkok, Thailand Arrhythmia 1

- h 0.99 (0.95, 1.04) Halonen et al. (2009 ) Helsinki, Finland Arrhythmia 8

- h max warm season 1.04 (0.80, 1.35) Peel et al. (2007 ) Atlanta, GA Dysrhythmia 8

- h warm season 1.01 (0.97, 1.06)

Polo niecki et al. (1997 ) London, England Arrhythmia 8

- h 1.02 (0.96, 1.07) Stieb et al. (2009 ) 7 Canadian cities Dysrhythmia 24

- h 1.02 (0.95, 1.09) Wong et al. (1999a ) Hong Kong Arrhythmia 24

- h 1.06 (0.99, 1.12)

24

- h warm season 1.10 (0.96, 1.26)

24

- h cold season 1.11 (1.01, 1.23)

*Studies included from Figure 6

- 25

.. Note: Change in O 3 standardized to 20 ppb for 24

- hour averaging period, 30 ppb for 8

- hour averaging period, and 40 ppb for 1

- hour averaging period (see Section 2.2). Ozone concentrations in ppb. Age groups of study populations were not specified or were adults with the exception of ( Wong et al., 1999a ) , which included only i ndividuals aged 65+. Studies listed in alphabetical order. Warm season defined as: March

- October ( Peel et al., 2007 ) , May

- October ( Wong et al., 1999a ) and May

- September ( Halonen et al., 2009 ) . Cold season defined as: November

- April ( Wong et al., 1999a )

.



### 6.3.2.8 Cardiovascular Mortality

As discussed within this section (Section 6.3 ), epidemiologic studies provide inconsistent 

### 1
evidence of an association betwe en short

- term O 3 exposure and cardiovascular effects. 

### 2 However, toxicological studies have demonstrated O 3 - induced cardiovascular effects, 

### 3 specifically enhanced atherosclerosis and ischemia, which could lead to death. The 2006 

### 4
O 3 AQCD provided evidence, pri marily from single

- city studies, of consistent positive 

### 5
associations between short

- term O 3 exposure and cardiovascular mortality. Recent 

### 6 multicity studies conducted in the U.S., Canada, and Europe further support the 

### 7
association between short

- term O 3 expos ure and cardiovascular mortality. 

### 8

As discussed in Section 6.2.7.2 , the APHENA study ( Katsouyanni et al., 2009 ) a lso 

### 9
examined associations between short

- term O 3 exposure and mortality and found 

### 10 consistent positive associations for cardiovascular mortality in all

- year analyses. 

### 11 However, in analyses restricted to the summer season, results were more variable with no 

### 12 evidence of an association in the Canadian dataset in the population <75 years of age, and 

### 13 evidence of associations persisting or increasing in magnitud e in the Canadian 

### 14 (population ≥ 75 years of age), U.S., and European datasets. Additional multicity studies 

### 15
from the U.S. ( Zanobetti and Schwartz, 2008b ) , Europe ( Samoli et al., 2009 ) , Italy 

### 16 ( Stafoggia et al., 2010 ) , and Asia ( Wong et al., 2010 ) that conducted summer season 

### 17

### Draft

– Do Not Cite or Quote 6

- 209 June 2012 and/or all

- year analyses provide additional support for an association between short

- term 

### 1
O 3 exposure and cardiovascular mortality ( Figu re 6

- 36 ). 

### 2

Of the studies evaluated, only the APHENA study ( Katsouyanni et al., 2009 ) and the 

### 3 Italian multicity study ( Stafoggia et al., 2010 ) conducted an analysis of the potential for 

### 4 copollutant confounding of the O 3 - cardiovascular mortality relationship. In the European 

### 5 dataset, when focusing on the natural spline m odel with 8 df/year (Section 6.2.7.2 ) and 

### 6 lag 1 results in order to compare results across study locations (Section 6.6.2.1 ), 

### 7 cardiovascular mortality risk estimates were robust to the inclusion of PM 10 in 

### 8 copollutant models in all

- year analyses with more variability in the Canadian and U.S. 

### 9
da tasets (i.e., cardiovascular O 3 mortality risk estimates were reduced or increased in 

### 10 copollutant models). In summer season analyses, cardiovascular O 3 mortality risk 

### 11 estimates were robust in the European dataset and attenuated but remained positive in the 

### 12 U.S. dataset. Similarly, in the Italian multicity study ( Stafoggia et al., 2010 ) , which was 

### 13 limited to the summer season, cardiovascular mortality risk estimates we re robust to the 

### 14
inclusion of PM 10 in copollutant models. Based on the APHENA and Italian multicity 

### 15 results, O 3 cardiovascular mortality risk estimates appear to be robust to inclusion of 

### 16
PM 10 in copollutant models. However, in the U.S. and Canadian datase ts there was 

### 17
evidence that O 3 cardiovascular mortality risk estimates are moderately to substantially 

### 18 sensitive (e.g., increased or attenuated) to PM 10 . The mostly every

- 6th

- day sampling 

### 19
schedule for PM 10 in the Canadian and U.S. datasets greatly reduced t heir sample size 

### 20 and limits the interpretation of these results. 

### 21

6.3.2.9 Summary of Epidemiologic Studies

Overall, the available body of evidence examining the relationship between short

- term 

### 22 exposures to O 3 concentrations and cardiovascular morbidity is inconsis tent. Across 

### 23 studies, different definitions, i.e., ICD

- 9 diagostic codes were used for both all

- cause and 

### 24

cause

- specific cardiovascular morbidity ( Table 6

- 35
, Table 6

- 36
, Table 6

- 37
, Table 6

- 38
, 

### 25
and Table 6

- 39 ), which may contribute to inconsistency in results. However, within 

### 26 diagnostic categories, no consistent pattern of association was found with O 3 . Generally, 

### 27
the studies summarized in this section used nearest air monitors to a ssess O 3 

### 28 concentrations, with a few exceptions that used modeling or personal exposure monitors 

### 29 (these exceptions were noted throughout the previous sections). The inconsistencies in 

### 30
the associations observed between short

- term O 3 and CVD morbidities are u nlikely to be 

### 31 explained by the different exposure assignment methods used (see Section 4.6 ). The wide 

### 32 variety of biomarkers considered and the lack of consistency among definitions used for 

### 33 specific cardiovascular disease endpoints (e.g., arrhythmias, HRV) make comparisons 

### 34 across studies difficult. Despite the inconsistent evidence for an association between O 3 

### 35

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- 210 June 2012 concentration and CVD morbidity, mortali ty studies indicate a consistent positive 

### 1
association between short

- term O 3 exposure and cardiovascular mortality in multicity 

### 2 studies and a multicontinent study

. 

### 3

6.3.3 Toxicology: Cardiovascular Effects

In the previous O 3 AQCDs ( U.S. EPA, 2006b
, 1996a ) experimental animal studies have 

### 4 reported relatively few cardiovascular system alterations after exposure to O 3 and other 

### 5 photochemical oxidants. The limited amount of research directed at examining 

### 6
O 3 - induced cardiovascular effects has primarily found alterations in heart rate (HR), heart 

### 7 rhythm, and BP af ter O 3 exposure. Although O 3 induced changes in HR and core 

### 8 temperature (T CO ) in a number of rat studies, these responses have not been reported or 

### 9 extensively studied in humans exposed to O 3 and may be unique to rodents. 

### 10

According to recent animal toxico logy studies, short

- term O 3 exposure induces vascular 

### 11 oxidative stress and proinflammatory mediators, alters HR and HRV, and disrupts the 

### 12 regulation of the pulmonary endothelin system (study details are provided in Table 6

- 40 ). 

### 13 A number of these effects were variable between strains examined, suggesting a genetic 

### 14 component to development of O 3 induced cardiovascular effects. Further, recent studies 

### 15 provi de evidence that extended O 3 exposure enhances the risk of ischemia

- reperfusion 

### 16 (I/R) injury and atherosclerotic lesion development. Still, few studies have investigated 

### 17
the role of O 3 reaction products in these processes, but more evidence is provided for 

### 18 elevated inflammatory and reduction

- oxidation (redox) cascades known to initiate these 

### 19 cardiovascular pathologies. 

### 20

Heart Rate, Rhythm, and Heart Rate Variability

Studies ( Arito et al., 1992 ; Arito et al., 1990 ; Uchiyama and Yokoyama, 1989 ; 

### 21 Yokoyama et al., 1989 ; Uchiyama et al., 1986 ) report O 3 exposure (0.2

- 1.0 ppm, 3 hours 

### 22
to 3 days) in rats decreased T CO , HR, and mean arterial pressure (MAP). In addition, O 3 

### 23

ex posure (0.1

– 1.0 ppm, 3 hours to 3 days) in rats induced arrhythmias, including 

### 24 increased PR interval and QRS complex, premature atrial contraction, and incomplete 

### 25
A

- V block ( Arito et al., 1990 ; Yokoyama et al., 1989 ; Uchiyama et al., 1986 ) . The effects 

### 26 were more pronounced in adult and awake rats than in younger or sleeping animals, 

### 27
wher eas no sex

- related differences were noted in these O 3 induced outcomes ( Uchiyama 

### 28 et al., 1986 ) . However, these cardiovascular responses to O 3 , including decreased T CO and 

### 29 HR, could be attenuated by increased ambient temperatures and environmental stress and 

### 30 exhibited adaptation ( Watkinson et al., 2003 ; Watkinson et al., 1993 ) . These studies 

### 31 suggest that these responses to O 3 were the result of the rodent hyp othermic response, 

### 32

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- 211 June 2012 which serves as a physiological and behavioral defense mechanism to minimize the 

### 1
irritant effects of O 3 inhalation, ( Iwasaki et al., 1998 ; Arito et al., 1997 ) . As humans do 

### 2 not appear to exhibit decreased HR, MAP, and T CO with routine environmental 

### 3 (Section 6.3.2 ) or controlled laboratory (Section 6.3.1 ) exposures to O 3 , caution must be 

### 4 used in extrapolating the results of these animal studies to humans. 

### 5

Other studies have shown that O 3 can increase BP in animal models. Rats exposed to 

### 6
0.6 ppm O 3 for 33 days had increased systolic pressure and HR ( Revis et al., 1981 )

. 

### 7 Increased BP triggers the release of atrial natriuretic factor (ANF), which has been found 

### 8 in increased levels in the heart, lungs, and circula tion of O 3 exposed (0.5 ppm) rats 

### 9 ( Vesely e t al., 1994a
, b
, c ) . Exposures to high concentrations of O 3 (1.0 ppm) have also 

### 10 been found to lead to heart and lung edema ( Friedman et al., 1983 ) , which could be the 

### 11 result of increased ANF levels. Thus, O 3 may increase blood pressure and HR, leading to 

### 12
increased ANF and tissue edema. 

### 13

Recent studies report strain differences in HR and HRV in response to a 2

- hour O 3 

### 14 pretreatment followed by exposure to carbon black (CB) in mice (C3H/HeJ [HeJ], 

### 15 C57BL/6J [B6], and C3H/HeOuJ [OuJ]) ( Hamade and Tankersley, 2009 ; Hamade et al., 

### 16
2008 ) . These mice strain s were chosen from prior studies on lung inflammatory and 

### 17 hyperpermeability responses to be at increased risk (B6 and OuJ) or resistant (HeJ) to 

### 18
O 3 - induced health effects ( Kleeberger et al., 2000 ) . HR decreased during O 3 pre

- exposure 

### 19 for all strains, but recovered during the CB exposure ( Hamade et al., 2008 ) . Percent 

### 20 change in HRV parameters, SDNN (indicating total HRV) and rMSSD (indicating beat



### 21

to

- beat HR V), were increased in both C3H mice strains, but not B6 mice, during O 3 

### 22

pre

- exposure and recovered during CB exposure when compared to the filtered air group. 

### 23 The two C3H strains differ by a mutation in the Toll

- like receptor 4 (TLR4) gene, but 

### 24
these effec ts did not seem to be related to this mutation since similar responses were 

### 25
observed. Hamade et al. (2008 ) speculate that the B6 and C3H strains differ in 

### 26 mechanisms of HR response after O 3 exposure between withdrawal of sympathetic tone 

### 27 and increase of parasympathetic tone; however, no direct evidence for this conclusion 

### 28 was reported. The strain differences observed in HR and HRV suggest that genetic 

### 29 variability affects cardiac responses after acute air pollutant exposures. 

### 30

Hamade and Tankersley (2009 ) continued this investigation of gene

- environment 

### 31 interactions on cardiopulmonary adaptation of O 3 and CB induced changes in HR and 

### 32 HRV using the previously described ( Hamade et al., 2008 ) daily exposure scheme for 3 

### 33
consecutive days. By comparing day

- 1 interim values it is possible to observe that O 3 

### 34 exposure increased SDNN and rMSSD, but decreased HR in all strains. Measures of HR 

### 35
and HRV in B6 and H eJ mice recovered to levels consistent with filtered air treated mice 

### 36 by day 3; however, these responses in OuJ mice remained suppressed. B6 mice had no 

### 37

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- 212 June 2012 change in respiratory rate (RR) after O 3 treatment, whereas HeJ mice on days 1 and 2 had 

### 1
increased RR a nd OuJ mice on days 2 and 3 exhibited increased RR. V T did not change 

### 2 with treatment among the strains. Overall, B6 mice were mildly responsive with rapid 

### 3 adaptation, whereas C3 mice were highly responsive with adaptation only in HeJ mice 

### 4 with regards to c hanges in cardiac and respiratory responses. HR and HRV parameters 

### 5 were not equally correlated with V T and RR between the three mice strains, which 

### 6 suggest that strains vary in the integration of the cardiac and respiratory systems. These 

### 7 complex interacti ons could help explain variability in interindividual responses to air 

### 8 pollution. 

### 9

Hamade et al. (2010 ) expanded their investigation to explore the variation of these strain 

### 10 dependent cardiopulmonary responses with age. As was observed previously, all 

### 11 experimental mouse strains (B6, HeJ, and OuJ) exhibited dec reased HR and increased 

### 12
HRV after O 3 exposure. Younger O 3 - exposed mice had a significa ntly lower HR 

### 13 compared to older exposed mice, indicating an attenuation of the bradycardic effect of O 3 

### 14 with age. Younger mice also had a greater increase in rMSSD in HeJ and OuJ strains and 

### 15 SDNN in HeJ mice. Conversely, B6 mice had a slightly greater increase in SDNN in 

### 16 aged mice compared to the young mice. No change was observed in the magnitude of the 

### 17
O 3 induced increase of SDNN in OuJ mice or rMSSD in B6 mice. The B6 a nd HeJ mice 

### 18 genetically vary in respect to the nuclear factor erythroid 2

- related factor 2 (Nrf

- 2). The 

### 19 authors propose that the genetic differences between the mice strains could be altering the 

### 20 formation of ROS, which tends to increase with age, thus mod ulating the changes in 

### 21 cardiopulmonary physiology after O 3 exposure. 

### 22

Strain and age differences in HR and heart function were further investigated in B6 and 

### 23 129S1/SvlmJ (129) mice in response to a sequential O 3 and filtered air or CB exposure 

### 24 ( Tankersley et a l., 2010 ) . Young 129 mice showed a decrease in HR after O 3 or O 3 and 

### 25 CB exposure. This bradycardia was not observed in B6 or older animals in this study, 

### 26 suggesting a possible alteration or adaptation of the autonomic nervous system activity 

### 27 with age. H owever, these authors did previously report bradycardia in similarly aged 

### 28 young B6 mice ( Hamade et al., 2010 ; Hamade and Tankersley, 2009 ; Hamade et al., 

### 29
2008 ) . Ozone exposure in 129 m ice also resulted in an increase in left ventricular 

### 30 chamber dimensions at end diastole (LVEDD) in young and old mice and a decrease in 

### 31 left ventricular posterior wall thickness at end systole (PWTES) in older mice. The 

### 32
increase in LVEDD caused a decrease in fractional shortening, which can be used as a 

### 33 rough indicator of left ventricular function. Regression analysis revealed a significa nt 

### 34 interaction between age and strain on HR and PWTES, which implies that aging affects 

### 35 HR and heart function in response to O 3 differently between mouse strains. 

### 36

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- 213 June 2012 Vascular Disease and Injury

A recent study in young mice (C57Bl/6) and rhesus monkeys examined the effects of 

### 1
short

- term O 3 exposure (0.5 ppm, 1 or 5 days) on a number of cardiovascular endpoints 

### 2 ( Chuang et al., 2009 ) . Mice exposed to O 3 for 5 days had increased HR as well as mean 

### 3 and diastolic blood pressure. This is in contrast to the bradycardia that was reported in 

### 4
18

- 20 week

- old B6 mice treated wi th O 3 , as described above ( Hamade and Tankersley, 

### 5
2009 ; Hamade et al., 20 08 ) . Increased blood pressure could be explained by the inhibition 

### 6
in endothelial

- dependent (acetylcholine) vasorelaxation from decreased bioavailability of 

### 7 aortic nitric oxide (·NO). Ozone caused a decrease in aortic NO X (nitrite and nitrate 

### 8 levels) and a decrease in to tal, but not phosphorylated, endothelial nitric oxide synthase 

### 9 (eNOS). Ozone also increased vascular oxidative stress in the form of increased aortic 

### 10 and lung lipid peroxidation (F2

- isoprostane), increased aortic protein nitration (3

- 

### 11 nitrotyrosine), decrea sed aortic superoxide dismutase (SOD2) protein and activity, and 

### 12 decreased aortic aconitase activity, indicating specific inactivation by O 2 - and ONOO -

. 

### 13 Mitochondrial DNA (mtDNA) damage was also used as a measure of oxidative and 

### 14
nitrative stress in mice a nd infant rhesus monkeys exposed to O 3 . Chuang et al. (2009 ) 

### 15 observed that mtDNA damage accumulated in the lung and aorta of mice after 1 and 

### 16
5 days of O 3 exposure and in the pr oximal and distal aorta of O 3 treated nonhuman 

### 17 primates. Additionally, genetically hyperlipidemic mice exposed to O 3 (0.5 ppm) for 

### 18
8 weeks had increased aortic atherosclerotic lesion area (Section 7.3.1 ), which may be 

### 19
associated with the short

- term exposure changes discussed. Overall, this study suggests 

### 20
that O 3 initiates an oxidative environment by increasing O 2 - production, which leads to 

### 21
mtDNA dama ge and ·NO consumption, known to perturb endothelial function ( Chuang 

### 22 et al., 2009 ) . Endothelial dysfunction is characteristic of early and advanced 

### 23 atherosclerosis and coincides with impaire d vasodilation and blood pressure regulation. 

### 24

Vascular occlusion resulting from atherosclerosis can block blood flow causing ischemia. 

### 25 The restoration of blood flow in the vessel or reperfusion can cause injury to the tissue 

### 26 from subsequent inflammation an d oxidative damage. Perepu et al. (2010 ) observed that 

### 27
O 3 expo sure (0.8 ppm, 28 or 56 days) enhanced the sensitivity to myocardial I/R injury in 

### 28 Sprague

- Dawley rats while increasing oxidative stress levels and pro

- inflammatory 

### 29 mediators and decreasing production of anti

- inflammatory proteins. Ozone was also 

### 30
found to decrease the left ventricular developed pressure, rate of change of pressure 

### 31 development, and rate of change of pressure decay while increasing left ventricular end 

### 32 diastolic pressure in isolated perfused hearts. In this ex vivo heart model, O 3 induced 

### 33
oxi dative stress by decreasing SOD enzyme activity and increasing malondialdehyde 

### 34 levels. Ozone also elicited a proinflammatory state which was evident by an increase in 

### 35
TNF

- α and a decrease in the anti

- inflammatory cytokine IL

- 10. Perepu et al. (2010 ) 

### 36
concluded that O 3 exposure may result in a greater I/R injury. 

### 37

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- 214 June 2012 Effects on Cardiovascular

- Related Proteins

Increased BP, changes in HRV, and increased atherosclerosis may be related to increases 

### 1 in the vasoconstrictor peptide, endothelin

- 1 (amino acids 1

- 21, ET

- 1 [1

- 21] ). Regulation of 

### 2 the pulmonary endothelin system can be affected in rats by inhalation of PM (0, 5, 

### 3
50 mg/m 3 , EHC

- 93) and O 3 ( Thomson et al., 2006 ; Thomson et al., 2005 ) . Exposure to 

### 4
either O 3 (0.8 ppm) or PM increased plasma ET

- 1 [1

- 21] , ET

- 3 [1

- 21] , and the ET

- 1 precursor 

### 5 peptide, bigET

- 1. Increases in circulating ET

- 1 [1

- 21] could be a result of a transient 

### 6 increase in the gene expression of lung preproET

- 1 and endothelin converting enzyme

- 1 

### 7 (ECE

- 1) immediately following inhalation of O 3 or PM. These latt er gene expression 

### 8 changes (e.g., preproET

- 1 and ECE

- 1) were additive with co

- exposure to O 3 and PM. 

### 9 Conversely, preproET

- 3 decreased immediately after O 3 exposure, suggesting the 

### 10
increase in ET

- 3 [1

- 21] was not through de novo production. A recent study al so found 

### 11
increased ET

- 1 gene expression in the aorta of O 3 - exposed rats ( Kodavanti et al., 2011 )

. 

### 12
These rats also exhibited an increase in ET B R after O 3 exposure; however, they did not 

### 13 demonstrate increased biomarkers for vascular inflammation, thrombosis, or oxidation. 

### 14

O 3 can oxidize protein functional groups and disturb the affected protein. For example, 

### 15 the soluble plasma p rotein fibrinogen is oxidized by O 3 (0.01

- 0.03 ppm) in vitro, creating 

### 16 fibrinogen and fibrin aggregates, characteristically similar to defective fibrinogen 

### 17 ( Rosenfeld et al., 2009 ; Rozenfeld et al., 2008 ) . In these studies, oxidized fibrinogen 

### 18
retained the ability to form fibrin gels that are involved in coagulation, however the 

### 19 aggregation time increased and the gels were rougher than normal with thicker fibers. 

### 20 Oxidized fibrinogen also developed the ability to self assemble creating fibrinogen 

### 21

aggrega tes that may play a role in thrombosis. Since O 3 does not readily translocate past 

### 22 the ELF and pulmonary epithelium and fibrinogen is primarily a plasma protein, it is 

### 23
uncertain if O 3 would have the opportunity to react with plasma fibrinogen. However, 

### 24
fib rinogen can be released from the basolateral face of pulmonary epithelial cells during 

### 25 inflammation, where the deposition of fibrinogen could lead to lung injury ( Lawrence 

### 26 and Simpson

- Haidaris, 2004 )

. 

### 27

Studies on Ozone Reaction Products

Although toxicological studies have demonstrated O 3 - induced effects on the 

### 28 cardiovascular system, it remains unclear if the mechanism is thr ough a reflex response 

### 29
or the result of effects from O 3 reaction products ( U.S. EPA, 2006b
, 1996a ) . Oxysterols 

### 30 derived from cholesterol ozonation, such as β

- epoxide and 5β,6β

- epoxycholesterol (and 

### 31
its metabolite cholestan

- 6

- oxo

- 3,5

- diol), have been implicated in in flammation associated 

### 32
with cardiovascular disease ( Pulfer et al., 2005 ; Pulfer and Murphy, 2004 ) . Two other 

### 33 cholesterol ozonolysis products, atheronal

- A and

- B (e.g., ch olesterol secoaldehyde), 

### 34

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- 215 June 2012 have been found in human atherosclerotic plaques and shown in vitro to induce foam cell 

### 1 formation and induce cardiomyocyte apoptosis and necrosis ( Sathishkumar et al., 2005 ; 

### 2 Wentworth et al., 2003 ) ; however, these products have not been found in the lung 

### 3 compartment or systemically after O 3 exposure. The ability to form these cholesterol 

### 4 ozonation products in the circulation in the absence of O 3 exposure complicates their 

### 5 implication i n O 3 induced cardiovascular disease. 

### 6

Although it has been proposed that O 3 reaction products released after the interaction of 

### 7
O 3 with ELF constituents (see Section 5.2.3 ) on O 3 interaction with ELF) are responsible 

### 8 for systemic effects, it is not known whether they gain access to the vascular space. 

### 9 Alternatively, extrapulmonary release of diffusible mediators, such as cytokines or 

### 10 endothelins, may initiate or propagate inflamma tory responses in the vascular or systemic 

### 11 compartments ( Cole and Freeman, 2009 ) (S ection 5.3.8 ). Ozone reacts within the lung to 

### 12 amplify ROS production, induce pulmonary inflammation, and activate inflammatory 

### 13 cells, resulting in a cascading proinflammatory state and extrapulmonary release of 

### 14 diffusible mediators that could lead to cardiovascular injury. 

### 15

A recent study that examined O 3 reaction byproducts has shown that cholesterol 

### 16 secoaldehyde (e.g., atheronal A) induces apoptosi s in vitro in mouse macrophages ( Gao 

### 17 et al., 2009b ) and cardiomyocytes ( Sathishkumar et al., 2009 ) . Additionally, atheronal

- A 

### 18
and

- B has been found to induce in vitro macrophage and endothelial cell 

### 19 proinflammatory events involved in the initiation of atherosclerosis ( Takeuchi et al., 

### 20
2006 ) . These O 3 reaction products when complexed with low density lipoprotein 

### 21 upregulate scavenger receptor class A and induce dose

- dependent macrophage 

### 22
chemotaxis. Atheronal

- A increases expression of the adhesion molecule, E

- selectin, in 

### 23 endothelial cells, while atheronal

- B induces monocyte differentiation. These events 

### 24 contribute to both monocyte recruitment and foam cell formation in atherosclerotic 

### 25
vessels. It is unknown whether these O 3 reaction products gain access to the vascular 

### 26 space from the lungs. Alternative explanations include the extrapulmonary release of 

### 27 diffusible mediators that may initiate or propagate inflammatory responses in the vascular 

### 28 or systemic compartments. 

### 29

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- 216 June 2012 Table 6

- 40 Characterization of study details for Section 6.3.3.

Study a * Model O 3 (ppm) Exposure Duration Effects
Chuang et al. (2009 ) Mice; C57Bl/6; M; 6 weeks 0.5 1 or 5 days, 8

- h/day Increased HR and blood pressure. Initiated an oxidative enviro nment by increasing vascular O 2 - production, which lead to mtDNA damage and ·NO consumption, known to perturb endothelial function. Monkey; rhesus Macaca mulatta ; M; Infant (180 days old) 0.5 5 days, 8

- h/day Increased aortic mtDNA damage.

Perepu et al. (2010 ) Rat; Sprague

- Dawley; 50

- 75 g 0.8 28 days, 8

- h/day Enhanced the sensitivity to myocardial I/R injury while increasing oxidative stress and pro

- inflammatory mediators and decreasing production of anti

- inflammatory proteins. Hamade et al. (2008 ) Mice; C57Bl/6J, C3H/HeJ, and C3H/HeOuJ; M; 18

- 20 weeks 0.6 (subsequent CB exp osure, 536 μg/m 3 ) 2

- h followed by 3 h of CB Decreased HR. Strain differences observed in HRV suggest that genetic variability affects cardiac responses.

Hamade and Tankersley (2009 ) Mice; C57Bl/6J, C3H/HeJ, and C3H/HeOuJ; M; 18

- 20 weeks 0.6 (subsequent CB exposure, 536 μg/m 3 ) 3 days, 2

- h/day followed by 3

- h of CB Strains varied in integration of the cardiac and respiratory systems, implications in interindividual variability. B6 mice were mildly responsive with rapid adaptation, whereas C3 mice were highly responsive with adaptation only in HeJ mice with regards to changes in cardiac and respiratory responses. Hamade et al. (2010 ) Mice; C57Bl/6J, C3H/HeJ, and C3H/HeOuJ; M; 5 or 12 mo old 0.6 (subsequent CB exposure, 536 μg/m 3 ) 2

- h followed by 3

- h of CB Aged mice exhibited attenuated changes in cardiopulmonary physiology after O 3 exposure. Genetic differences between mice strains could be altering formation of ROS, which tends to increase with age, thus modulating O 3 induced effects. Tankersley et al. (2010 ) Mice; C57Bl/6J, 129S1/SvlmJ; M/F; 5 or 18 mo old 0.6 (subsequent CB exposure, 556 μg/m 3 ) 2

- h followed by 3

- h of CB Significa nt interaction between age and strain on HR and PWTES, which implies that aging affects the HR and function in response to O 3 differently between mouse strains.

Thomson et al. (2005 ) Rat; Fischer

- 344; M; 200

- 25 0 g 0.4 or 0.8 4

- h Activation of the vasoconstricting ET system. Increased plasma ET

- 1 through higher production and slower clearance.

Thomson et al. (2006 ) Rat; Fischer

- 344; M; 200

- 250 g 0.8 4

- h Increased p lasma ET

- 3 not due to de novo synthesis, unlike ET

- 1.

Kodavanti et al. (2011 ) Rat; Wistar; M; 10

- 12 weeks 0. 5 or 1.0 2 days, 5

- h/day No changes to aortic genes of thrombosis, inflammation, or proteolysis, except ET

- 1 and ETBR (1.0 ppm).

a Results from previous studies are presented in Table AX5

- 14 of the 2006 O 3 AQCD and Table 6

- 23 of the 1996 O 3 AQCD. *Study details for Section 6.3.3 a

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- 217 June 2012 Summary of Toxicological Studies

Overall, animal studies suggest that O 3 exposure may result in O 3 induced cardiovascular 

### 1 effects. Studies provide evidence for both increased and decreased HR, however it is 

### 2
uncertain if O 3 - induced bradycardia would also occur in humans or if it is due solely to a 

### 3 rodent hypothermic response. Animal studies also provide evidence for increased HRV, 

### 4 arrhythmias, vascular disease, and injury following short

- term O 3 exposure. In addition, a 

### 5 series of studies highlight the role of gene

- environment interactions and age in the 

### 6 induction of effects and attenuation of responses t o O 3 exposure. 

### 7

Biologically plausible mechanisms are present for the cardiovascular effects observed in 

### 8 animal exposure studies, however there is a lack of coherence with controlled human 

### 9 exposure and epidemiologic studies. Further discussion of the modes of action that may 

### 10
lead to cardiovascular effects can be found in Section 5.3.8 . Recent studies suggest that 

### 11
O 3 exposure may disrupt both the NO ̇ and endothelin systems, which can result in an 

### 12 increase in HR, HRV, and ANF. The observed bradycardia following O 3 exposure may 

### 13 be the result of reflex reactions, including the trigeminocardiac reflex, evoked following 

### 14
th e stimulation of sensory receptors lining the nose and RT. These mechanisms of 

### 15 parasympathetically

- derived cardiac effects are described in more detail in Section 5.3.2

. 

### 16 Additionally, O 3 may increase oxidative stress and vascular inflammation promoting the 

### 17 progression of atherosclerosis and leading to increased susceptibility to I/R injury. As O 3 

### 18 reacts quickly with the ELF and does not translocate to the heart and large vessels, 

### 19 studies suggest that the cardiovascular effects exhibited could be caused by reaction 

### 20 byproducts of O 3 exposure. However, direct evidence of translocation of O 3 reaction 

### 21 products to the cardiovascular system has not been demon strated in vivo. Alternatively, 

### 22 extrapulmonary release of diffusible mediators, such as cytokines or endothelins, may 

### 23 initiate or propagate inflammatory responses in the vascular or systemic compartments 

### 24 leading to the reported cardiovascular pathologies. 

### 25

6.3.4 Summary and Causal Determination

In previous O 3 reviews ( U.S. EPA, 2006b
, 1996a ) very few studies examined the effect of 

### 26
short

- term O 3 exposure on the cardiovascular system. More recently, the body of 

### 27
scientific evidence available that has examined the effect of O 3 on the cardiovascular 

### 28 system has adv anced, but overall still remains small. 

### 29

Although limited in number, toxicological studies have provided evidence of O 3 - induced 

### 30 cardiovascular effects. Animal toxicological studies have reported enhanced I/R injury, 

### 31 disrupted NO

- induced vascular reactivity, decreased cardiac function, increased vascular 

### 32 disease, and increased HRV following short

- term O 3 exposure. The observed increase in 

### 33

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– Do Not Cite or Quote 6

- 218 June 2012 HRV is supported by a recent controlled human exposure study that also found increased 

### 1 high frequency HRV, but not altered blood pressure, following O 3 exposure ( Fakhri et al., 

### 2
2009 ) . Toxicological studies investigating the role of O 3 in heart rate regulation are 

### 3 mixed with both bradycardic and tachycardic res ponses observed. However, these 

### 4 changes in cardiac function provide preliminary evidence for O 3 - induced modulation of 

### 5 the autonomic nervous system leading to cardiovascular complications. It is still 

### 6
uncertain how O 3 inhalation may cause systemic toxicity; however the cardiovascular 

### 7
effects of O 3 found in animals correspond to the development and maintenance of an 

### 8 extrapulmonary oxidative, proinflammatory environment that may result from pulmonary 

### 9
inflammation. 

### 10

The epidemiologic studies evaluated do not sup port the evidence of O 3 - induced 

### 11 cardiovascular effects observed in the toxicological studies. This is highlighted by the 

### 12 multiple studies that examined the association between short

- term O 3 exposure and 

### 13
cardiovascular

- related hospital admissions and ED vis its and other various cardiovascular 

### 14 effects and found no evidence of a consistent relationship with O 3 exposure. Although 

### 15
there is inconsistent evidence for O 3 - induced cardiovascular morbidity in the 

### 16 epidemiologic literature, single

- city studies reviewed in the 2006 O 3 AQCD, and recent 

### 17 multicity studies, and a multicontinent study demonstrate consistent positive associations 

### 18
between short

- term O 3 exposure and cardiovascular mortality. Additionally, O 3 mortality 

### 19 associations were found to remain robust in copollutant models with PM. However, the 

### 20
lack of coherence between the results from studies that examined associations between 

### 21
short

- term O 3 exposure and cardiovascular morbidity and subsequently cardi ovascular 

### 22 mortality complicate the interpretation of the overall evidence for O 3 - induced 

### 23
cardiovascular effects. 

### 24

In conclusion, animal toxicological studies provide some evidence for O 3 - induced 

### 25 cardiovascular effects, but the effects observed were not cons istently supported by 

### 26 controlled human exposure studies or epidemiologic studies. Although the toxicological 

### 27 evidence provides initial support to the relatively strong body of evidence indicating 

### 28
O 3 - induced cardiovascular mortality, there is a lack of cohe rence with controlled human 

### 29 exposure and epidemiologic studies of cardiovascular morbidity which together do not 

### 30 support O 3 - induced cardiovascular effects. Thus, the overall body of evidence across 

### 31 disciplines is suggestive of a causal relationship between relevant short

- term 

### 32 exposures to O 3 and cardiovascular effect s. 

### 33

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– Do Not Cite or Quote 6

- 219 June 2012 

## 6.4 Central Nervous System Effects

The 2006 O 3 AQCD included toxicological evidence that acute exposures to O 3 are 

### 1 associated with alterations in neurotransmitters, motor activity, short and lo ng term 

### 2 memory, and sleep patterns. Additionally, histological signs of neurodegeneration have 

### 3 been observed. Reports of headache, dizziness, and irritation of the nose with O 3 

### 4 exposure are common complaints in humans, and some behavioral changes in animal s 

### 5 may be related to these symptoms rather than indicative of neurotoxicity. Peterson and 

### 6 Andrews (1963 ) and Tepper et al. (1983 ) showed that mice would alter their behavior to 

### 7
avoid O 3 exposure. Murphy et al. (1964 ) and Tepper et al. (1982 ) showed that running



### 8 wheel behavior was suppressed, and Tepper et al. (1985 ) subsequently demonstrated the 

### 9
effects of a 6

- hour exposure to O 3 on the suppression of running

- wheel behavior in rats 

### 10 and mice, with the lowest effective concentration being about 0.12 ppm O 3 in the rat and 

### 11
about 0.2 ppm in the mouse. The suppression of a ctive behavior by 6 hours of exposure 

### 12
to 0.12 ppm O 3 has recently been confirmed by Martrette et al. (2011 ) in juvenile female 

### 13 rats, and the suppression of three different active behavior parameters was found to 

### 14 become more pronounced after 15 days of exposure. A table of studies examining the 

### 15
effects of O 3 on behavior can be found on p 6

- 128 o f the 1996 O 3 AQCD. Generally 

### 16 speaking, transient changes in behavior in rodent models appear to be dependent on a 

### 17 complex interaction of factors such as (1) the type of behavior being measured, with 

### 18 some behaviors increased and others suppressed; (2) the factors motivating that behavior 

### 19 (differences in reinforcement); and (3) the sensitivity of the particular behavior 

### 20 (e.g., active behaviors are more affected than more sedentary behaviors). Many 

### 21 behavioral changes are likely to result from avoidance of irr itation, but more recent 

### 22
studies indicate that O 3 also directly affects the CNS. 

### 23

Research in the area of O 3 - induced neurotoxicity has notably increased over the past few 

### 24 years, with the majority of the evidence coming from toxicological studies that examin ed 

### 25
the association between O 3 exposure, neuropathology, and neurobehavioral effects, and 

### 26 more limited evidence from epidemiologic studies. In an epidemiologic study conducted 

### 27 by Chen and Schwartz (2009 ) , data from the NHANES III cohort was utilized to study 

### 28 the relationship between long

- term O 3 exposure (mean annual O 3 concentration of 

### 29
26.5 ppb) and neurobehavioral effects among adults aged 20

- 59 years. The authors 

### 30
observed an association between annual exposure to O 3 and tests measuring coding 

### 31 ability and attention/short

- term memory. Each 10

- ppb increase in annual O 3 levels 

### 32 corresponded to an aging

- related cognitive performance decline of 3.5 years for coding 

### 33 ability and 5.3 ye ars for attention/short

- term memory. These associations persisted in 

### 34 both crude and adjusted models. There was no association between annual O 3 

### 35
concentrations and reaction time tests. The authors conclude that overall there is a 

### 36 positive association betwee n O 3 exposure and reduced performance on neurobehavioral 

### 37

### Draft

– Do Not Cite or Quote 6

- 220 June 2012 tests. Although Chen and Schwartz (2009 ) is a long

- term exposure study, it is included in 

### 1
this section because it is t he first epidemiologic study to demonstrate that exposure to 

### 2
ambient O 3 is associated with decrements in neurocognitive tests related to memory and 

### 3 attention in humans. This epidemiologic evidence of an effect on the CNS due to 

### 4 exposure to ambient concentr ations of O 3 is coherent with animal studies demonstrating 

### 5 that exposure to O 3 can produce a variety of CNS effects including behavioral deficits, 

### 6 morphological changes, and oxidative stress in the brains of rodents. In these rodent 

### 7 studies, interestingly, CNS effects were reported at O 3 concentrations that were generally 

### 8 lower than those concentrations commonly observed to produce pulmonary or cardiac 

### 9
effects in rats. 

### 10

A number of new studies demonstrate various perturbations in neurologic function or 

### 11
hist ology, including changes similar to those observed with Parkinson’s and Alzheimer’s 

### 12 disease pathologies occurring in similar regions of the brain ( Table 6

- 41 ). Many of these 

### 13 include exposure durations ranging from short

- term to long

- term, and as such are 

### 14
discussed here and in Chapter 7 with emphasis on the effects resulting from exposure 

### 15 durations relevant to the respective chapter. Several studies assess short

- and long

- term 

### 16 memory acquisition via passive avoidance behavio ral testing and find decrements in test 

### 17 performance after O 3 exposure, consistent with the aforementioned observation made in 

### 18 humans by Chen and Schwartz (2009 ) . Impairment of long

- term memory has been 

### 19 previously described in rats exposed to 0.2 ppm O 3 for 4 hours ( Rivas

- Arancibia et al., 

### 20
1998 ) and in other studies of 4

- hour exposures at concentrations of 0.7 to 1 ppm ( Dorado



### 21 Martinez et al., 2001 ; Rivas

- Arancibia et al., 2000 ; Avila

- Costa et al., 1999 ) . More 

### 22 recently, statistically significa nt decreases in both short and long

- term memory were 

### 23
observed in rats after 15 days of exposure to 0.25 ppm O 3 ( Rivas

- Arancibia et al., 2010 )

. 

### 24

The central nervous system is very sensitive to oxidative stress, due in part to its high 

### 25 content of polyunsaturated fatty acids, high rate of oxygen consumption, and low 

### 26
antioxidant enzyme capacity. Oxidative stress has been identified as one of the 

### 27 pathophysiological mechanisms underlying neurodegenerative disorders such as 

### 28 Parkinson’s and Alzheimer’s disease, among others ( Simonian and Coyle, 1996 ) . It is 

### 29 also believed to play a role in altering hippocampal function, which causes cognitive 

### 30
deficits with aging ( Vanguilder and Freeman, 2011 ) . A particularly common finding in 

### 31
studies of O 3 - exposed rats is lipid peroxidation in the br ain, especially in the 

### 32 hippocampus, which is important for higher cognitive function including contextual 

### 33 memory acquisition. Performance in passive avoidance learning tests is impaired when 

### 34 the hippocampus is injured, and the observed behavioral effects a re well correlated with 

### 35 histological and biochemical changes in the hippocampus, including reduction in spine 

### 36 density in the pyramidal neurons ( Avila

- Costa et al., 1999 ) , lipoperoxidation ( Rivas



### 37 Arancibia et al., 2010 ; Dorado

- Martinez et al., 2001 ) , progressive neurodegeneration, and 

### 38

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– Do Not Cite or Quote 6

- 221 June 2012 activated and phagocytic microglia ( Rivas

- Arancibia et al., 2010 ) . The hippocampus is 

### 1 also one of the main regions affected by age

- related neurodegenerative diseases, 

### 2 including Alzheimer’s disease, and it may be more sensitive to oxidative damage in aged 

### 3 rats. In a study of young (47 days) and aged (900 days) rats exposed to 1 ppm O 3 for 4 h, 

### 4
O 3 - induced lipid peroxidation occurred to a greate r extent in the striatum of young rats, 

### 5 whereas it was highest in the hippocampus in aged rats ( Rivas

- Arancibia et al., 2000 )

. 

### 6
Martínez

- Canabal and Angora

- Perez (2008 ) showed exposure of rats to 0.25 p pm, 

### 7 4h/day, for 7, 15, or 30 days increased lipoperoxides in the hippocampus. This effect was 

### 8
observed at day 7 and continued to increase with time, indicating cumulative oxidative 

### 9 damage. O 3 - induced changes in lipid peroxidation, neuronal death, and COX

- 2 positive 

### 10 cells in the hippocampus could be significa ntly inhibited by daily treatment with growth 

### 11 hormone (GH), which declines with age in most species. The protective effect of GH on 

### 12

- induced oxidative stress was greatest at 15 days of exposure and was n on

- significa nt at 

### 13 day 30. Consistent with these findings, lipid peroxidation in the hippocampus of rats was 

### 14
observed to increase significa ntly after a 30

- day exposure to 0.25 ppm , but not after a 

### 15 single 4

- hour exposure to the same concentration ( Mokoena et al., 2010 ) . However, 

### 16
4 hours of exposure was sufficient to cause significa nt increases in lipid peroxidation 

### 17
when the concentration was increased to 0.7 ppm, and another study observed lipid 

### 18 peroxidation after a 4

- hour exposure to 0.4 ppm ( Dorado

- Martinez et al., 2001 )

. 

### 19

Other commonly affected areas of the brain include the striatum, substantia nigra, 

### 20 cerebellum, olfactory bulb, and frontal/prefrontal cortex. The striatum and subst antia 

### 21 nigra are particularly sensitive to oxidative stress because the metabolism of dopamine, 

### 22 central to their function, is an oxidative process perturbed by redox imbalance. Oxidative 

### 23 stress has been implicated in the premature death of substantia nigra dopamine neurons in 

### 24
Parkinson’s disease. Angoa

- Pérez et al. (2006 ) have shown progressive lipoperoxidation 

### 25 in the substantia nigra and a decrease in nigral dopamine neurons in ovariectomized 

### 26 female rats exposed to 0.25 ppm O 3 , 4h/day, for 7 , 15, or 30 days. Estradiol, an 

### 27 antioxidant, attenuated O 3 - induced oxidative stress and nigral neuronal death, and the 

### 28 authors note that in humans, estrogen therapy can ameliorate symptoms of Parkinson’s 

### 29 disease, which is more prevalent in men. Progressive oxidative stress has also been 

### 30 observed in the striatum and substantia nigra of rats after 15 and 30 days of exposure to 

### 31
0.25 ppm O 3 for 4 h/day, along with a loss of dopaminergic neurons from the substantia 

### 32 nigra ( Pereyra

- Muñoz et al., 2006 ) . Decreases in mot or activity were also observed at 15 

### 33
and 30 days of exposure, consistent with other reports ( Martrette et al., 2011 ; Dorado



### 34 Martinez et al., 2001 ) . Using a similar O 3 exposure protocol, Santiago

- López et al. (2010 ) 

### 35 also observed a progressive loss of dopaminergic neurons within the substantia nigra, 

### 36 accompanied by alterations in the morphology of remaining cells and an increase in p53 

### 37
levels and nuclear translocation. 

### 38

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– Do Not Cite or Quote 6

- 222 June 2012 The olfactory bulb also undergoes oxi dative damage in O 3 exposed animals, in some 

### 1 cases altering olfactory

- dependent behavior. Lipid peroxidation was observed in the 

### 2 olfactory bulbs of ovariectomized female rats exposed to 0.25 ppm O 3 (4 h/day) for 30 or 

### 3
60 days ( Guevara

- Guzmán et al., 2009 )

. O 3 also induced decrements in a selective 

### 4 olfactory recognition memory test, and the authors note that early deficits in odor 

### 5 perception and memory are components of human neurodegenerative diseases. The 

### 6 decrements in olfactory memory were not due to dama ged olfactory perception based on 

### 7 other tests. However, deficits in olfactory perception emerged with longer exposures 

### 8 (discussed in Chapter 7 ). As with the study by Angoa

- Pérez et al. (2006 ) described 

### 9 above, a protective effect for estradiol was demonstrated for both lipid peroxidation and 

### 10 olfactory memory defects. The role of oxidative stress in memory deficits and associated 

### 11 morphol ogical changes has also been demonstrated via attenuation by other antioxidants 

### 12 as well, such as α

- tocopherol ( Guerrero et al., 1999 ) and taurine ( Rivas

- Arancibia et al., 

### 13
2000 ) .It is unclear how persistent these effects might be. One study of acute exposure, 

### 14 using 1 ppm O 3 for 4 hours, observed morphological changes in the olfactory bulb of rats 

### 15
at 2 hours, and 1 and 10 days, but not 15 days, after exposure ( Colín

- Barenque et al., 

### 16
2005 )

. 

### 17

Other acute studies also report changes in the CNS. Lipid peroxidation was observed in 

### 18 multiple regions of the brain after a 1

- to 9

- hour exposure to 1 ppm O 3 ( Escalante



### 19 Membrillo et al., 2005 ) . Ozone has also been shown to alter gene expression of 

### 20
endo thelin

- 1 (pituitary) and inducible nitric oxide synthase (cerebral hemisphere) after a 

### 21 single 4

- hour exposure to 0.8 ppm O 3 , indicating potential cerebrovascular effects. This 

### 22
concentration

- dependent effect was not observed at 0.4 ppm O 3 ( Thomson et al., 2007 )

. 

### 23 Vascular endothelial growth factor was upregulated in astroglial cell s in the central 

### 24 respiratory areas of the brain of rats exposed to 0.5 ppm O 3 for 3 hours ( Araneda et al., 

### 25
2008 ) . The persistence of CNS changes after a single exposure was also examined and 

### 26 the increase in vascular endothelial growth factor was present after a short (3 hours) 

### 27 recovery period. Th us, there is evidence that O 3 - induced CNS effects are both 

### 28
concentration

- and time

- dependent. 

### 29

Because O 3 can produce a disruption of the sleep

- wake cycle ( U.S. EPA, 2006b )
, Alfaro



### 30 Rodríguez and González

- Piña (2005 ) examined whether acetylcholine in a region of the 

### 31 brain involved in sleep regulation was altered by O 3 . After a 24

- hour exposure to 0.5 ppm 

### 32
O 3 , the acetylcholine concentration in the medial preoptic area was decreased by 58% and 

### 33 strongly correlated with a disruption in paradoxical sleep. Such behavioral

- biochemical 

### 34
effects of O 3 are confirmed by a number of studies which have demon strated 

### 35 morphological and biochemical changes in rats. 

### 36

### Draft

– Do Not Cite or Quote 6

- 223 June 2012 CNS effects have also been demonstrated in newborn and adult rats whose only exposure 

### 1
to O 3 occurred in utero. Several neurotransmitters were assessed in male offspring of 

### 2 dams exposed to 1 ppm O 3 duri ng the entire pregnancy ( Gonzalez

- Pina et al., 2008 ) . The 

### 3
data showed that catecholamine neurotransmitters were affected to a greater degree than 

### 4
indole

- amine neurotransmitters in the cerebellum. CNS changes, including behavioral, 

### 5 cellular, and biochemical effects, have also been observed after in utero exposure to 

### 6
0.5 ppm O 3 fo r 12 h/day from gestational days 5

- 20 ( Boussouar et al., 2009 ) . Tyrosine 

### 7 hydroxylase labeling in the nucleus tractus solatarius was increased after in utero 

### 8 exposure to O 3 wherea s Fos protein labeling did not change. When these offspring were 

### 9 challenged by immobilization stress, neuroplasticity pathways, which were activated in 

### 10
air

- exposed offspring, were inhibited in O 3 - exposed offspring. Although an O 3 exposure 

### 11
C

- R was not studi ed in these two in utero studies, it has been examined in one study. 

### 12 Santucci et al. (2006 ) investigated behavioral effects and gene expression after in utero 

### 13 exposure of mice to as little as 0.3 ppm O 3 . Increased defensive/submissive behavior an d 

### 14 reduced social investigation were observed in both the 0.3 and 0.6 ppm O 3 groups. 

### 15 Changes in gene expression of brain

- derived neurotrophic factor (BDNF, increased in 

### 16 striatum) and nerve growth factor (NGF, decreased in hippocampus) accompanied these 

### 17
beha vioral changes. Thus, these three studies demonstrate that CNS effects can occur as a 

### 18 result of in utero exposure to O 3 , and although the mode of action of these effects is not 

### 19 known, it has been suggested that circulating lipid peroxidation products may p lay a role 

### 20 ( Boussouar et al., 2009 ) . Importantly, these CNS effects occurred in rodent models after 

### 21 in utero only exposure to relevant concentrations of O 3 . 

### 22

### Draft

– Do Not Cite or Quote 6

- 224 June 2012 Table 6

- 41 Central nervous system and behavioral effects of short

- term ozone exposure in rats

Study Model O 3 (ppm) Exposure Duration Effects

Martrette et al. (2011 ) Rat; Wistar; F; Weight: 152g; 7 weeks old 0.12 1

- 15 days, 6 h/day Significa nt decrease in rearing, locomotor activity, and jumping activity at day 1, with a further decrease in these activities by day 15. Angoa

- Pérez et al. (2006 ) Rat; Wistar; F; Weight: 300g; ovariectomized 0.25 7 to 60 days, 4

- h/day, 5 days /week Progressive lipid peroxidation and loss of tyrosine hydrolase

- immunopositive neurons in the substantia nigra starting at 7 days.

Guevara

- Guzmán et al. (2009 ) Rat; Wistar; F; 264g; ovariectomized 0.25 30 and 60 days, 4h/day Estradiol treatment protected against lipid peroxidation and decreases in estrogen receptors and dopamine β

- hydroxylase in olfactory bulbs along with deficits in olfactory recognition memory.

Martínez

- Canabal and Angora

- Perez (2008 ) Rat; Wistar; M; Weight: 300g 0.25 7 to 30 days, 4

- h/day G rowth hormone inhibited O 3 - induced increases in lipoperoxidation and COX

- 2 positive cells in the hippocampus. Pereyra

- Muñoz et al. (2006 ) Rat; Wistar; M; 250

- 300g 0.25 15 and 30 days, 4

- h/day Decreased motor activity, increased lipid peroxidation, altered morphology, and loss of dopamine neurons in substantia nigra and striatum, increased expression of DARPP

32, iNOS, and SOD.

Rivas

- Arancibia et al. (2010 ) Rat; Wistar; M; 250

- 300g 0.25 15 t o 90 days, 4

- h/ day Ozone produced significa nt increases in lipid peroxidation in the hippocampus, and altered the number of p53 positive immunoreactive cells, activated and phagocytic microglia cells, GFAP immunoreactive cells, and doublecortine cells, a nd short

- and long

- term memory

retention latency. Santiago

- López et al. (2010 ) Rat; Wistar; M; 250

- 300g 0.25 15, 30, and 60 days, 4

- h/day Progressive loss of dopamine reactivity in the substantia nigra, along with morphological changes. Increased p53 levels and nuclear translocation.

Thomson et al. (2007 ) Rat; Fischer

- 344; M; 200

- 250g 0.4; 0.8 4

- h; assays at 0 and 24 h postexposure At 0.8 ppm, O 3 produced rapid perturbations in the ET

- NO pathway gene expression in the brain. Ozone induced a small but significa nt time

- and concentration

depen dent increase in prepro

- endothelin

- 1 mRNA levels in the cerebral hemisphere and pituitary, whereas TNFa and iNOS mRNA levels were decreased at 0 h and unchanged or increased, respectively, at 24 h.

Alfaro

- Rodríguez and González

- Piña (2005 ) Rat; Wistar; M; 292g 0.5 24

- h During the light phase, O 3 caused a significa nt decrease in paradoxical sleep accompanied by a significa nt decrease in Ach levels in the hypothalamic medial preoptic area. The same effects occurred during the dark phase exposure to O 3 in addition to a significa nt in crease in slow

wave sleep and decrease in wakefulness. Araneda et al. (2008 ) Rats; Sprague

Dawley; M; 280

- 320g 0.5 3

- h (measurements taken at 0 h and 3 h after exposure) Ozone upregulated VEGF in astroglial cells located in the respiratory center of the brain. VEGF co

- located wit h IL

- 6 and TNF in cells near blood vessel walls, and blood vessel area was markedly increased.

### Draft

– Do Not Cite or Quote 6

- 225 June 2012 Study Model O 3 (ppm) Exposure Duration Effects

Boussouar et al. (2009 ) Rat; Sprague

Dawley; M; adult offspring of prenatally exposed dams; 403

- 414g 0.5 From embryonic day E5 to E20 for 1

- h/day; immobilization stress Prenatal O 3 exposure had a long term impact on the nucleus tractus solitarius of adult rats, as revealed during immobilization stress.

Soulage et al. (2004 ) Rat; Sprague

Dawley; M; Approx. 7 weeks old 0.7 5

- h Ozone produced differential effects on peripheral and central components of the sympatho

- adrenal system. While catecholamine biosynthesis was increased in portions of the brain, the catecholamine turnover rate was significa ntly increased in the heart and c erebral cortex and inhibited in the lung and striatum.

Calderón Guzmán et al. (2006 ); ( 2005 ) Rat; Wistar; M; 21 days old; well

- nourished and malnourished groups 0.75 15 successive days for 4

- h/day A significa nt decrease in body weight was observed in both well nourished (WN) and malnourished (MN) rats after O 3 exposure. Localized ATPase, TBARS, and GSH levels changed in response to O 3 in certain brain areas and the O 3 - induced changes were dependent on nutritional condition.

Colín

- Barenque et al. (2005 ) Rats; Wistar; M; 250

- 300g 1.0 4

- h; assays at 2

- h, 24

- h, 10 days, and 15 days after exposure A significa nt loss of dendritic spines in granule cells of the olfactory bulb occurred at 2 hrs to 10 days after exposure. Cytological and ultrastructural chan ges returned towards normal morphology by 15 days.

Escalante

- Membrillo et al. (2005 ) Rats; Wistar; M; 280

- 320g 1.0 1

- , 3

- , 6

- , or 9

- h Significa nt increases in TBARS occurred in hypothalamus, cortex, striatum, midbrain, thalamus, and pons. Partial but significa nt recovery was observed by 3 h afte r the 9 h exposure.
Gonzalez

- Pina et al. (2008 ) Rat; Wistar; M; 1 12

- h/day, 21 days of gestation; assays at 0, 5, & 10 days postnatal Prenatal O 3 exposure produced significa nt decreases in cerebellar monoamine but not indolamine content at 0 and 5 days after birth with a partial recovery by 10 days. 5

- hydroxy

- indole

- acetic acid levels were significa ntly increased at 10 days.



### 6.4.1 Neuroendocrine Effects

According to the 2006 O 3 AQCD, early studies suggested an interaction of O 3 with the 

### 1 pituitary

- thyroid

- adrenal axis, because thyroidectomy, hypophysectomy, and 

### 2 adrenalectomy protected against the lethal effects of O 3 . Concentrations of 0.7

- 1.0 ppm 

### 3
O 3 for a 1

- day exposure in male rats caused changes in the parathyroid, thymic atro phy, 

### 4 decreased serum levels of thyroid hormones and protein binding, and increased prolactin. 

### 5 Increased toxicity to O 3 was reported in hyperthyroid rats and T3 supplementation was 

### 6 shown to increase metabolic rate and pulmonary injury in the lungs of O 3 - tre ated animals. 

### 7 The mechanisms by which O 3 affects neuroendocrine function are not well understood, 

### 8 but previous work suggests that high ambient levels of O 3 can produce marked neural 

### 9 disturbances in structures involved in the integration of chemosensory inp uts, arousal, 

### 10

### Draft

– Do Not Cite or Quote 6

- 226 June 2012 and motor control, effects that may be responsible for some of the behavioral effects seen 

### 1
with O 3 exposure. A more recent study exposing immature female rats to 0.12 ppm O 3 

### 2
demonstrated significa ntly increased serum levels of the thyroid hor mone free T 3 after 

### 3
15 days of exposure, whereas free T 4 was unchanged ( Martrette et al., 2011 ) . These 

### 4 results are in contrast to those previously presented whereby 1 ppm O 3 for 1 day 

### 5 significa ntly decreased T 3 and T 4 ( Clemons and Garcia, 1980 ) , although comparisons are 

### 6 made difficult by highly disparate exposure regimens along with sex differences. 

### 7 Martrette et al. (2011 ) also demonstrated significa ntly increased co rticosterone levels 

### 8
after 15 days of exposure, suggesting a stress related response. 

### 9

6.4.2 Summary and Causal Determination

In rodents, O 3 exposure has been shown to cause physicochemical changes in the brain 

### 10
indicative of oxidative stress and inflammation. New er toxicological studies add to earlier 

### 11 evidence that acute exposures to O 3 can produce a range of effects on the central nervous 

### 12 system and behavior. Previously observed effects, including neurodegeneration, 

### 13 alterations in neurotransmitters, short and lon g term memory, and sleep patterns, have 

### 14 been further supported by recent studies. In instances where pathology and behavior are 

### 15 both examined, animals exhibit decrements in behaviors tied to the brain regions or 

### 16 chemicals found to be affected or damaged. F or example, damage in the hippocampus, 

### 17 which is important for memory acquisition, was correlated with impaired performance in 

### 18 tests designed to assess memory. Thus the brain is functionally affected by O 3 exposure. 

### 19 The single epidemiologic study conducted showed an association between O 3 exposure 

### 20 and memory deficits in humans as well, albeit on a long

- term exposure basis. Notably, 

### 21 exposure to O 3 levels as low as 0.25 ppm for 7 days has resulted in progressive 

### 22 neurodegeneration and deficits in both short and long

- term memory in rodents. 

### 23 Examination of changes in the brain at lower exposure concentrations or at 0.25 ppm for 

### 24 shorter durations has not been reported, but 0.12 ppm O 3 has been shown to alter 

### 25 behavior. It is possible that some behavioral changes may reflect avoidance of irritation 

### 26 as opposed to functional changes in brain morphology or chemistry, but in many cases 

### 27 functional changes are related to oxidative stress and damage. In some instances, changes 

### 28 were dependent on the nutritional status of the rats (high versus low protein diet). For 

### 29 example, O 3 produced an increase in glutathione in the brains of rats fed the high protein 

### 30 diet but decreases in glutathione in rats fed low protein chow ( Calderón Guzmán et al., 

### 31
2006 ) . The hippocampus, one of the main regions affected by age

- related 

### 32 neurodegenerative disease s, appears to be more sensitive to oxidative damage in aged rats 

### 33 ( Rivas

- Arancibia et al., 2000 ) , and growth hormone, which declines with age in most 

### 34 species, may be protectiv e ( Martínez

- Canabal and Angora

- Perez, 2008 ) . Developing 

### 35

### Draft

– Do Not Cite or Quote 6

- 227 June 2012 animals may also be sensitive, as changes in the CNS, including biochemical, cellular, 

### 1 and behavioral effects, have been observed in juvenile and adult animals whose sole 

### 2 exposure occurred in utero, at levels as a low as 0.3 ppm. A number of studies 

### 3
demonstrate O 3 - induced changes that are also observed in human neurodegenerative 

### 4 disorders such as Alzheimer’s and Parkinson’s disease, including signs of oxidative 

### 5 stress, loss of neurons/neuronal death, reductions in dopamine levels, increased C OX

- 2 

### 6 expression, and increases in activated microglia in important regions of the brain 

### 7 (hippocampus, substantia nigra). 

### 8

Thus, evidence for neurological effects from epidemiologic and controlled human 

### 9 exposure studies is lacking. However, the toxicological evidence for the impact of O 3 on 

### 10
the brain and behavior is strong, and suggestive of a causal relationship between O 3 

### 11 exposure and effects on the central nervous system. 

### 12



## 6.5 Effects on Other Organ Systems

6.5.1 Effects on the Liver and Xenobiotic Metab olism

Early investigations of the effects of O 3 on the liver centered on xenobiotic metabolism, 

### 13 and the prolongation of drug

- induced sleeping time, which was observed at 0.1 ppm O 3 

### 14 ( Graham et al., 1981 ) . In some species, only adults and especially females were affected. 

### 15
In rat s, high (1.0

- 2.0 ppm for 3 hours) acute O 3 exposures caused increased production of 

### 16 NO by hepatocytes and enhanced protein synthesis ( Laskin et al., 1996 ; Laskin et al., 

### 17
1994 ) . Except for the earlier work on xenobiotic metabolism, the responses occurred only 

### 18 after very high acute O 3 exposures. One study, conducted at 1 ppm O 3 exposure, has been 

### 19
identified ( Last et al., 2005 ) in which alterations in gene expression underlying 

### 20
O 3 - induced cachexia and downregulation of xenobiotic metabolism were examined. A 

### 21
number of the downregulat ed genes are known to be interferon (IFN) dependent, 

### 22 suggesting a role for circulating IFN. A more recent study by Aibo et al. (2010 ) 

### 23 demonstrates exacerbation of acetaminophen

- induced liver injury in mice after a single 

### 24
6

- hour exposure to 0.25 or 0.5 ppm O 3 . Data indicate that O 3 may worsen drug

- induced 

### 25 liver injury by inhibiting hepatic repair. The O 3 - associated effects shown in the liver are 

### 26 thought to be mediated by inflammatory cytokines or other cytotoxic mediators released 

### 27 by activated macrophages o r other cells in the lungs ( Laskin and Laskin, 2001 ; Laskin et 

### 28 al., 1998 ; Vin cent et al., 1996a ) . Recently, increased peroxidated lipids were detected in 

### 29 the plasma of O 3 exposed animals ( Santiago

- López et al., 2010 )

. 

### 30

In summary, mediators generated by O 3 exposure may cause effects on the liver in 

### 31 laboratory rodents. Ozone exposures as low as 0.1 ppm have been shown to affect 

### 32

### Draft

– Do Not Cite or Quote 6

- 228 June 2012 drug

- induced sleeping time, and exposure to 0.25 ppm can exacerbate liver injury 

### 1 induced by a common analgesic. However, very few studies at relevant concentrations 

### 2 have been conducted, and no data from controlled human exposure or epidemiologic 

### 3
studies are cur rently available. Therefore the collective evidence is inadequate to 

### 4 determine if a causal relationship exists between short

- term O 3 exposure and 

### 5 effects on the liver and metabolism. 

### 6

6.5.2 Effects on Cutaneous and Ocular Tissues

In addition to the lungs, the ski n is highly exposed to O 3 and contains O 3 reactive targets 

### 7 (polyunsaturated fatty acids) that can produce lipid peroxides. The 2006 O 3 AQCD ( U.S. 

### 8 EPA, 2006b ) reported that although there is evidence of oxidative stress at near ambient 

### 9
O 3 concentrations, skin and eyes are only affected at high concentrations (greater than 

### 10
1

- 5 ppm). Ozone exposure (0.8 ppm for 7 days) induces oxidative stress in the skin of 

### 11 hairless mice, along with proinflammatory cytokines ( Valacchi et al., 2009 ) . A recent 

### 12 study demonstrated that 0.25 ppm O 3 differentially alters expression of 

### 13 metalloproteinases in the skin of young and aged mice, indicating that age may 

### 14 potentially increase risk of oxidative stress ( Fortino et al., 20 07 ) . In young mice, healing 

### 15
of skin wounds is not significa ntly affected by O 3 exposure ( Lim et al., 2006 ) . However, 

### 16 exposure to 0.5 ppm O 3 for 6 h/day significa ntly delays wound closure in aged mice. As 

### 17
with effects on the liver described ab ove, the effects of O 3 on the skin and eyes have not 

### 18 been widely studied, and information from controlled human exposure or epidemiologic 

### 19 studies is not currently available. Therefore the collective evidence is inadequate to 

### 20
determine if a causal relations hip exists between short

- term O 3 exposure and 

### 21 effects on cutaneous and ocular tissues. 

### 22



## 6.6 Mortality

6.6.1 Summary of Findings from 2006 Ozone AQCD

The 2006 O 3 AQCD reviewed a large number of time

- series studies consisting of single



### 23 and multicity studies, and met a

- analyses. In the large U.S. multicity studies that 

### 24
examined all

- year data, summary effect estimates corresponding to single

- day lags 

### 25 ranged from a 0.5

- 1% increase in all

- cause (nonaccidental) mortality per a standardized 

### 26
unit increase in O 3 of 20 ppb for 24

- h avg, 30 ppb for 8

- h max, and 40 ppb for 1

- h max as 

### 27
discussed in Section 2.2 . The association between short

- term O 3 exposure and mortality 

### 28

was substantiated by a collection of meta

- analyses and international multicity studies. 

### 29

### Draft

– Do Not Cite or Quote 6

- 229 June 2012 The studies evaluated found some evidence for heterogeneity in O 3 mortality risk 

### 1 estimates across cities and studies. Studies that conducted seasonal analyses, although 

### 2

mo re limited in number, reported larger O 3 mortality risk estimates during the warm or 

### 3 summer season. Overall, the 2006 O 3 AQCD identified robust associations between 

### 4 various measures of daily ambient O 3 concentrations and all

- cause mortality, with 

### 5
additiona l evidence for associations with cardiovascular mortality, which could not be 

### 6 readily explained by confounding due to time, weather, or copollutants. However, it was 

### 7 noted that multiple uncertainties remain regarding the O 3 - mortality relationship 

### 8 including : the extent of residual confounding by copollutants; factors that modify the 

### 9
O 3 - mortality association; the appropriate lag structure for identifying O 3 - mortality effects 

### 10 (e.g., single

- day lags versus distributed lag model); the shape of the O 3 - mortality C

- R 

### 11 function and whether a threshold exists; and the identification of susceptible populations. 

### 12 Collectively, the 2006 O 3 AQCD concluded that “the overall body of evidence is highly 

### 13 suggestive that O 3 directly or indirectly contributes to non

- accidental and 

### 14 cardiopulmonary

- related mortality.” 

### 15

6.6.2 Associations of Mortality and Short

- Term Ozone Exposure

Recent studies that examined the association between short

- term O 3 exposure and 

### 16 mortality further confirmed the associations reported in the 2006 O 3 AQCD. New 

### 17
mul ticontinent and multicity studies reported consistent positive associations between 

### 18
short

- term O 3 exposure and all

- cause mortality in all

- year analyses, with additional 

### 19 evidence for larger mortality risk estimates during the warm or summer months 

### 20 ( Figure 6

- 26 ; Table 6

- 42 ). These associations were rep orted across a range of ambient O 3 

### 21 concentrations that were in some cases quite low ( Table 6

- 43 ). 

### 22

### Draft

– Do Not Cite or Quote 6

- 230 June 2012 Note: Effect estimates are for a 40 ppb increase in 1

- h max, 30 ppb increase in 8

- h max, and 20 ppb increase in 24

- h avg O 3 concentrations. An “a” represent multicity studies and meta

- analyses from the 2006 O 3 AQCD. Bell et al. (2005 )
, Ito et al. (2005 )
, and Levy et al. (2005 ) used a range of lag days in the meta

- analysis: Lag 0, 1, 2, or average 0

- 1 or 1

- 2; single

- day lags from 0 to 3; and lag 0 and 1

- 2; respectively. A “b” represents risk estimates from APHENA

- Canada standardized to an approximate IQR of 5.1 ppb for a 1

- h max increase in O 3 concentrations (see explanation in Section 6.2.7.2 ).


### Figure 6

- 26 Summary of mortality risk estimates for short

- term ozone exposure and all

- cause (nonaccidental) mortality from all

- year and summer season analyses. Study Gryparis et al. (2004) Bell et al. (2007) Schwartz (2005) Bell and Dominici (2008) Bell et al. (2004)a Levy et al. (2005)a Katsouyanni et al. (2009) Bell et al. (2005)a Ito et al. (2005)a Wong et al. (2010) Katsouyanni et al. (2009) Cakmak et al. (2011) Katsouyanni et al. (2009) Katsouyanni et al. (2009)b Samoli et al. (2009) Bell et al. (2004)a Schwartz (2005) Zanobetti and Schwartz (2008) Zanobetti and Schwartz (2008) Franklin and Schwartz (2008) Gryparis et al. (2004) Medina

- Ramon and Schwartz (2008) Katsouyanni et al. (2009) Bell et al. (2005)a Katsouyanni et al. (2009) Katsouyanni et al. (2009)b Levy et al. (2005)a Ito et al. (2005)a Katsouyanni et al. (2009) Stafoggia et al. (2010) Location APHEA2 (23 cities) 98 U.S. communities 14 U.S. cities 98 U.S. communities 95 U.S. communities

U.S. and Non

- U.S. APHENA

- Europe U.S. and Non

- U.S. U.S. and Non

- U.S.

PAPA (4 cities) APHENA

- U.S. 7 Chilean cities APHENA

- Canada APHENA

- Canada 21 European cities 95 U.S. communities 14 U.S. cities 48 U.S. cities 48 U.S. cities 18 U.S. communities APHEA2 (21 cities)

48 U.S. cities APHENA

- Europe U.S. and Non

- U.S. APHENA

- Canada APHENA

- Canada U.S. and Non

- U.S. U.S. and Non

- U.S.

APHENA

- U.S. 10 Italian cities Lag
0

- 1 0

- 1 0 0

- 6 0

- 6 DL(0

- 2)

0

- 1 DL(0

- 2) DL(0

- 6) DL(0

- 2) DL(0

- 2)

0

- 1 0

- 6 0 0 0

- 3 0 0

- 1 0

- 2 DL(0

- 2) DL(0

- 2) DL(0

- 2)

DL(0

- 2) DL(0

- 5) ► All

- Year

Summer

- 1 1 3 5 7 9 11
% Increase

### Draft

– Do Not Cite or Quote 6

- 231 June 2012 Table 6

- 42 Corresponding effect estimates for Figure 6

- 26.

Study * Location Lag Avg Time % Increase (95% CI)

All

- year Gryparis et al. (2004 ) APHEA2 (23 cities) 0

- 1 1

- h max 0.24 (

- 0.86, 1.98) Bell et al. (2007 ) 98 U.S. communities 0

- 1 24

- h avg 0.64 (0.34, 0.92) Schwartz (2005a ) 14 U.S. cities 0 1

- h max 0.76 (0.13, 1.40) Bell and Dominici (2008 ) 98 U.S. communities 0

- 6 24

- h avg 1.04 (0.56, 1.55) Bell et al. (2004 ) a 95 U.S. communities 0

- 6 24

- h avg 1.04 (0.54, 1.55) Levy et al. (2005 ) a U.S. and Non

- U.S.

--- 24

- h avg 1.64 (1.25, 2.03) Katsouy anni et al. (2009 ) APHENA

- europe DL(0

- 2) 1

- h max 1.66 (0.47, 2.94) Bell et al. (2005 ) a U.S. and Non

- U.S.

--- 24

- h avg 1.75 (1.10, 2.37) ( Ito et al., 2005 ) a U.S. and Non

- U.S.

--- 24

- h avg 2.20 (0.80, 3.60) ( Wong et al., 2010 ) PAPA (4 cities) 0

- 1 8

- h avg 2.26 (1.36, 3.16) Katsouyanni et al. (2009 ) APHENA

- U.S. DL(0

- 2) 1

- h max 3.02 (1.10, 4.89) Cakmak et al. (2011 ) 7 Chilean cities DL(0

- 6) 8

- h max 3.35 (1.07, 5.75) Katsouyanni et al. (2009 ) APHENA

- Canada DL(0

- 2) 1

- h max 5.87 (1.82, 9.81) Katsouyanni et al. (2009 ) b APHENA

- Canada DL(0

- 2) 1

- h max 0.73 (0.23, 1.20)
Summer
Samoli et al. (2009 ) 21 European cities 0

- 1 8

- h max 0.66 (0.24, 1.05) Bell et al. (2004 ) a 95 U.S. communities 0

- 6 24

- h avg 0.78 (0.26, 1.30) Schwartz (2005a ) 14 U.S. cities 0 1

- h max 1.00 (0.30, 1.80) Zanobetti and Schwartz (2 008a ) 48 U.S. cities 0 8

- h max 1.51 (1.14, 1.87) Zanobetti and Schwartz (2008b ) 48 U.S. cities 0

- 3 8

- h max 1.60 (0.84, 2.33) Franklin and Schwartz (2008 ) 18 U.S. communities 0 24

- h avg 1.79 (0.90, 2.68) Gryparis et al. (2004 ) APHEA2 (21 cities) 0

- 1 8

- h max 1.80 (0.99, 3.06)

Medina

- Ramón and Schwartz (2008 ) 48 U.S. cities 0

- 2 8

- h max 1.96 (1.14, 2.82) Katsouyanni et al. (2009 ) APHENA

- europe DL(0

- 2) 1

- h max 2.38 (0.87, 3.91) Bell et al. (2005 ) a U.S. and Non

- U.S.

--- 24

- h avg 3.02 (1.45, 4.63) Katsouyanni et al. (2009 ) APHENA

- Canada DL(0

- 2) 1

- h max 3.34 (1.26, 5.38) Katsouyanni et al. (2009 ) APHENA

- Canada DL(0

- 2) 1

- h max 0.42 (0.16, 0.67) Levy et al. (2005 ) a U.S. and Non

- U.S.

--- 24

- h avg 3.38 (2.27, 4.42) Ito et al. (2005 ) a U.S. and Non

- U.S.

--- 24

- h avg 3.50 (2.10, 4.90) Katsouyanni et al. (2009 ) APHE NA

- U.S. DL(0

- 2) 1

- h max 3.83 (1.90, 5.79) Stafoggia et al. (2010 ) 10 Italian cities DL(0

- 5) 8

- h max 9.15 (5.41, 13.0)

*Studies included from Figure 6

- 26

. .
a Multicity studies and meta

- analyses from the 2006 O 3 AQCD. Bell et al. (2005 ) a

, Ito et al. (2005 ) a , and Levy et al. (2005 ) a used a range of lag days in the meta

- analysis: Lag 0, 1, 2, or aver age 0

- 1 or 1

- 2; Single

- day lags from 0

- 3; and Lag 0 and 1

- 2; respectively.

b Risk estimates from APHENA

- Canada standardized to an approximate IQR of 5.1 ppb for a 1

- h max increase in O 3 concentrations (see explanation in Section 6.2.7.2 ).

### Draft

– Do Not Cite or Quote 6

- 232 June 2012 Table 6

- 43 Range of mean and upper percentile ozone concentrations in previous and recent multicity studies.

Study Location Years Averaging Time Mean Concentration (ppb) a Upper Percentile Concentrations (ppb) a
Gryparis et al. (2004 ) b 23 European cities (APHEA2) 1990

- 1997 1

- h max 8

- h max Summer:
1

- h max: 44

- 117 8

- h max: 30

- 99 Winter:
1

- h max: 11

- 57 8

- h max: 8

- 49 Summer:
1

- h max: 62

- 173 8

- h max: 57

- 154 Winter:
1

- h max: 40

- 88 8

- h max: 25

- 78

Schwartz (2005a ) b 14 U.S. cities 1986

- 1993 1

- h max 35.1

- 60 25th: 26.5

- 52 75th: 46.3

- 69 Bell et al. (2004 ) 95 U.S. communities (NMM APS) 1987

- 2000 24

- h avg 26.0 NR

Bell et al. (2007 ) 98 U.S. communities (NMMAPS) 1987

- 2000 24

- h avg 26.0 d NR

Bell and Dominici (2008 ) 98 U.S. communities (NMMAPS) 1987

- 2000 (All year and May

- September) 24

- h avg All year: 26.8 May

- September: 30.0 Maximum: All year: 37.3 May

- September: 47.2

Franklin and Schwartz (2008 ) 18 U.S. communities 2000

- 2005 (May

- September) 24

- h avg 21.4

- 48.7 NR

Katsouy anni et al. (2009 ) b,e NMMAPS 12 Canadian cities (APHEA2) 1987

- 1996 (Canada and U.S.) varied by city for Europe 1

- h max U.S.: 13.3

- 38.4 Canada: 6.7

- 8.4 Europe:18.3

- 41.9 75th: U.S.: 21.0

- 52.0 Canada: 8.7

- 12.5 Europe: 24.0

- 65.8

Medina

- Ramón and Schwartz (2008 ) b 48 U.S. cities 1989

- 2000 (May

- September) 8

- h max 16.1

- 58.8 NR

Samoli et al. (2009 ) b 21 European cities (APHEA2) 1 990

- 1997 (June

- August) 8

- h max 20.0

- 62.8 75th: 27.2

- 74.8

Stafoggia et al. (2010 ) 10 Italian cities 2001

- 2005 (April

- September) 8

- h max 41.2

- 58 .9 75th: 47.0

- 71.6

Cakmak et al. (2011 ) 7 Chilean cities 1997

- 2007 8

- h max 59.0

- 87.6 NR

Wong et al. (2010 ) PAPA (4 cities) 1999

- 2003 (Bangkok) 1996

- 2002 (Hong Kong) 2001

- 2004 (Shanghai) 2001

- 2004 (Wuhan) 8

- h avg 18.7

- 43.7 75th: 38.4

- 60.4 Max: 92.1

- 131.8

Zanobetti and Schwartz (2008b ) 48 U.S. cities 1989

- 2000 (June

- August) 8

- h max 15.1

- 62.8 Max: 34.3

- 146.2 75th: 19.8

- 75.9

### Draft

– Do Not Cite or Quote 6

- 233 June 2012 Study Location Years Averaging Time Mean Concentration (ppb) a Upper Percentile Concentrations (ppb) a

Zanobetti and Schwartz (2008a ) 48 U.S. citiesc 1989

- 2000 (Winter: Dec

- Feb) (Spring: March

- May) (Summer: June

- Aug) (Autumn: Sept

- Nov) 8

- h max Winter: 16.5 Spring: 41.6 Summer: 47.8 Autumn: 33.5 Max: Winter: 40.6 Spring: 91.4 Summer: 103.0 Autumn: 91.2

a O 3 concentrations were converted to ppb if the study presented them as μg/m 3 by using the conversion factor of 0.51 assuming standard temperature (25° C) and pressure (1 atm). b Study only reported median O 3 concentrations.

c Cities with less than 75% observa tions in a season excluded. As a result, 29 cities examined in winter, 32 in spring, 33 in autumn, and all 48 in the summer. d Bell et al. (2007 ) did not report mean O 3 concentrations, however, it used a similar dataset as Bell et al. (2004 ) which consisted of 95 U.S. communities for 1987

- 2000. For comparison purposes the 24

- h avg O 3 concentrations for the 95 communities from Bell et al. (2004 ) are reported here.

e Study did not present air quality data for the summer months.

In addition to examining the relationship between short

- term O 3 exposure and all

- cause 

### 1 mortality, recent studies attempted to address the uncertainties that remained upon the 

### 2 completion of the 2006 O 3 AQCD. As a result, given the robust associations between 

### 3
short

- term O 3 exposure and mortality presented across studies in the 2006 O 3 AQCD and 

### 4 supported in the new multicity studies ( Figure 6

- 26 ), the following sections primarily 

### 5 focus on the examination of previously identified uncertainties in the O 3 - mortality 

### 6 relationship, specifically: O 3 associations with cause

- specific mortality, confounding, lag 

### 7 structure (e.g., multiday effects and mortality displacement), effect modification 

### 8 (i.e., sources of heterogeneity in risk estimates across cities); and the O 3 - mortality C

- R 

### 9 relationship. Focusing specifically on these uncertainties allows for a more detailed 

### 10 characterization of the relationship between short

- term O 3 exposure and mortality. 

### 11

6.6.2.1 Confounding

Recent epidemiologic studies examined potential confounders of the O 3 - mortality 

### 12 relationship. These studies specifically focused on whether PM and its constituents or 

### 13
seasonal trends confounded the association between short

- term O 3 exposure and 

### 14 mortality. 

### 15

Confou nding by PM and PM C onstituents

An important question in the evaluation of the association between short

- term O 3 

### 16 exposure and mortality is whether the relationship is confounded by particulate matter, 

### 17 particularly the PM chemical components that are found in the “summer haze” mixture 

### 18
which also contains O 3 . However, because of the temporal correlation among these PM 

### 19 components and O 3 , and their possible interactions, the interpretation of results from 

### 20

### Draft

– Do Not Cite or Quote 6

- 234 June 2012 copollutant models that attempt to disentangle the healt h effects associated with each 

### 1 pollutant is challenging. Further complicating the interpretation of copollutant results, at 

### 2 times, is the every

- 3rd or

- 6th day PM sampling schedule employed in most locations, 

### 3 which limits the number of days where both PM a nd O 3 data is available. 

### 4

The potential confounding effects of PM 10 and PM 2.5 on the O 3 - mortality relationship 

### 5 were examined by Bell et al. (2007 ) using data on 98 U.S. urban communities for the 

### 6 years 1987

- 2000 from the National Morbidity, Mortality, and Air Pollution Study 

### 7 (NMMAPS). In this analysis the authors included PM as a covariate in time

- series 

### 8 models, and also examined O 3 - mortality associations on days when O 3 concentrations 

### 9 were below a specified value. This analysis was limited by the small fraction of days 

### 10
when both PM and O 3 data were available, due to the every

- 3rd

- or 6th

- day sampling 

### 11 schedule for the PM indices, and the limited amount of city

- specific data for PM 2.5 

### 12 because it was only collected in most cities since 1999. As a result, of the 91 

### 13
communities with PM 2.5 data, only 9.2% of days in the study period had data for both O 3 

### 14
and PM 2.5 , resulting in the use of only 62 communities in the PM 2.5 analysis. An 

### 15 examination of the correlation between PM (PM 10 and PM 2.5 ) and O 3 across various strata 

### 16 of daily PM 10 and PM 2. 5 concentrations found that neither PM size fraction was highly 

### 17 correlated with daily O 3 concentrations across any of the strata examined. These results 

### 18 were also observed when using 8

- h max and 1

- h max O 3 exposure metrics. National and 

### 19 community

- specific effect estimates of the association between short

- term O 3 exposure 

### 20 and mortality were robust to inclusion of PM 10 or PM 2.5 in time

- series models through the 

### 21 range of O 3 concentrations (i.e., <10 ppb, 10

- 20, 20

- 40, 40

- 60, 60

- 80, and >80 ppb). 

### 22
Even with the small number of days in which both PM 2.5 and O 3 data was available, the 

### 23 percent increases in nonaccidental deaths per 10 ppb increase 24

- h avg O 3 concentrations 

### 24 at lag 0

- 1 day were 0.22% (95% CI:

- 0.22, 0.65) without PM 2.5 and 0.21% (95% CI: 

### 25

- 0.22, 0.64) w ith PM 2.5 in 62 communities. 

### 26

Although strong correlations between PM and O 3 were not reported by Bell et al. (2007 ) 

### 27 the patterns observed suggest regional differences in their correlation ( Table 6

- 44 ). Both 

### 28
PM 10 and PM 2.5 show positive correlations with O 3 in the Industrial Midwest, Northeast, 

### 29 Urban Midwest, and Southeast, especially in the summer months, presumably, because of 

### 30 the summer peaking sulfate. However, the mostly negative or weak correlations between 

### 31
PM and O 3 in the summer in the Southwest, Nor thwest, and southern California could be 

### 32
due to winter

- peaking nitrate. Thus, the potential confounding effect of PM on the 

### 33
O 3 - mortality relationship could be influenced by the relative contribution of sulfate and 

### 34 nitrate, which varies regionally and seaso nally. 

### 35

### Draft

– Do Not Cite or Quote 6

- 235 June 2012 Table 6

- 44 Correlations between PM and ozone by season and region.

No. of Communities Winter Spring Summer Fall Yearly

PM 10 Industrial Midwest 19 0.37 0.44 0.44 0.39 0.41

Northeast 15 0.34 0.44 0.36 0.44 0.40

Urban Midwest 6 0.24 0.25 0.22 0.26 0.24

Southwest 9 0.00 0.02

- 0.02 0.10 0.03

Northwest 11

- 0.17

- 0.20

- 0.13

- 0.11

- 0.16

Southern California 7 0.19 0.08 0.12 0.19 0.14

Southeast 25 0.33 0.35 0.31 0.31 0.32
U.S. 93 0.23 0.26 0.24 0.26 0.25

PM 2.5 Industrial Midwest 19 0.18 0.39 0.43 0.44 0.36

Northeast 13 0.05 0.26 0.16 0.43 0.25

Urban Midwest 4 0.22 0.31 0.15 0.32 0.20

Southwest 9

- 0.15

- 0.08

- 0.17

- 0.15

- 0.14

Northwest 11

- 0.32

- 0.34

- 0.39

- 0.24

- 0.31

Southern California 7

- 0.25

- 0.22

- 0.25

- 0.15

- 0.23

Southeast 26 0.38 0.47 0.30 0.37 0.39
U.S. 90 0.09 0.21 0.12 0.22 0.16

Source: Bell et al. (2007 )

.

### Draft

– Do Not Cite or Quote 6

- 236 June 2012 Note: The diagonal line indicates 1:1 ratio. Source: Reprinted with permission of Informa UK Ltd, ( Smith et al., 2009b )

. 

### Figure 6

- 27 Scatter plots of ozone mortality risk estimates with versus without adjustment for PM 10 

### in NMMAPS cities.

In an attempt to reassess a number of issues associated with the O 3 - mortality relationship, 

### 1 including confounding, Smith et al. (2009b ) re

- analyzed the publicly available NMMAPS 

### 2 database for the years 1987

- 2000. Similar to Bell et al. (2007 ) , the PM 10 data used in the 

### 3 Smith et al. (2009b ) analysis con sisted primarily of every

- 6th day data. In analyses 

### 4 conducted to examine the potential confounding effects of PM 10 , the authors reported 

### 5 that, in most cases, O 3 mortality risk estimates were reduced by between 22% and 33% in 

### 6 copollutant models. This is fur ther highlighted in Figure 6

- 27 , which shows scatter plots 

### 7
of O 3 - mortality risk estimates with adjustment for PM 10 versus without adjustment for 

### 8
PM 10 . Smith et al. (2009b ) point out that a larger fraction (89 out of 93) of the posterior 

### 9 estimates lie below the diagonal line (i.e., esti mates are smaller with PM 10 adjustment) 

### 10 compared to the raw estimates (56 out of 93). This observation could be attributed to both 

### 11 sets of posterior estimates being calculated by “shrinking towards the mean” along with 

### 12 the small number of days where both P M 10 and O 3 data was available. However, the most 

### 13

### Draft

– Do Not Cite or Quote 6

- 237 June 2012 prominent feature of these plots is that the variation of O 3 - mortality risk estimates across 

### 1 cities is much larger than the impact of PM 10 adjustment on the O 3 - mortality relationship. 

### 2

Franklin and Schwartz (2008 ) examined the sensitivity of O 3 mortality risk estimates to 

### 3
the inclusion of PM 2. 5 or PM chemical components associated with secondary aerosols 

### 4 (e.g., sulfate [SO 4 2

- ], organic carbon [OC], and nitrate [NO 3 - ]) in copollutant models. 

### 5 This analysis consisted of between 3 and 6 years of data from May through September 

### 6
2000

- 2005 from 18 U.S . communities. The association between O 3 and non

- accidental 

### 7 mortality was examined in single

- pollutant models and after adjustment for PM 2.5 , 

### 8 sulfate, organic carbon, or nitrate concentrations. The single

- city effect estimates were 

### 9
combined into an overal l estimate using a random

- effects model. In the single

- pollutant 

### 10 model, the authors found a 0.89% (95% CI: 0.45, 1.33%) increase in nonaccidental 

### 11 mortality with a 10 ppb increase in same

- day 24

- hour summertime O 3 concentrations 

### 12
across the 18 U.S. communiti es. Adjustment for PM 2.5 mass, which was available for 

### 13 84% of the days, decreased the O 3 - mortality risk estimate only slightly (from 0.88% to 

### 14 0.79%), but the inclusion of sulfate in the model reduced the risk estimate by 31% (from 

### 15 0.85% to 0.58%). However, sulfate data were only available for 18% of the days. 

### 16 Therefore, a limitation of this study is the limited amount of data for PM 2.5 chemical 

### 17 components due to the every

- 3rd

- day or every

- 6th

- day sampling schedule. For example, 

### 18 when using a subset of days w hen organic carbon measurements were available (i.e., 17% 

### 19 of the available days), O 3 mortality risk estimates were reduced to 0.51% (95% CI:

- 0.36 

### 20 to 1.36) in a single

- pollutant model. 

### 21

Consistent with the studies previously discussed, the results from Franklin and Schwartz 

### 22 (2008 ) also demonstrate that the interpretation of the potential con founding effects of 

### 23 copollutants on O 3 mortality risk estimates is not straightforward as a result of the PM 

### 24 sampling schedule employed in most cities. However, Franklin and Schwartz (2008 ) find 

### 25
that O 3 - mortality risk estimates, although attenuated in some cases (i.e., sulfate), remain 

### 26 positive. As presented in Figure 6

- 28 , the regional and city

- to

- city variations in O 3 

### 27 mortality risk estimates appear greater than the impact of adjusting for copollutants. In 

### 28 addition, in some cases, a negative O 3 mortality risk estimate becomes even more 

### 29 negative with the inclusion of sulfate (e.g., Seattle) in a copollutant model, or a null O 3 

### 30 mortality risk estimate becomes negative when sulfate is included (e.g., Dallas and 

### 31 Detroit). Thus, the reduction in the overall O 3 mortality risk estimate (i.e., across cities) 

### 32 needs to be assessed in the context of the heterogeneity in the single

- city estimates. 

### 33

### Draft

– Do Not Cite or Quote 6

- 238 June 2012 Source: Franklin and Schwartz (2008 )

. 

### Figure 6

- 28 Community

- specific ozone

- mortality risk estimates for nonaccidental mortality per 10 ppb increase in same

- day 24

- h average summertime ozone concentrations in single

- pollutant models and copollutant models with sulfate.

In the APHENA study, the investigators from the U.S. (NMMAPS), Canadian, and 

### 1 European (APHEA2) multicity studies collaborated and conducted a joint analysis of 

### 2
PM 10 and O 3 using each of these datasets ( Katsouyanni et al., 2009 ) . For mortality, each 

### 3 dataset consisted of a different number of cities and years of air quality data: U.S. 

### 4 encompassed 90 cities with daily O 3 data from 1987

- 1996 of which 36 cities had summer 

### 5 only O 3 measurements; Europe included 23 cities with 3

- 7 yea rs of daily O 3 data during 

### 6
1990

- 1997; and Canada consisted of 12 cities with daily O 3 data from 1987 to 1996. As 

### 7
discussed in Section 6.2.7.2 , the APHENA study conducted extensive sensitivity 

### 8 analyses, of which the 8 df/year results for both the penalized spline (PS) and natural 

### 9 spline (NS) models are presented in the text for comparison purposes, but only the NS 

### 10

### Draft

– Do Not Cite or Quote 6

- 239 June 2012 results are presented in figures beca use alternative spline models have previously been 

### 1
shown to result in similar effect estimates ( HEI, 2003 ) . Additionally, for the Canadian 

### 2 results, figures contain risk estimates standardized to both a 40 ppb increment for 

### 3
1

- h max O 3 concentrations, consistent with the rest of the ISA, but also the approximate 

### 4 IQR across the Canadian citie s as discussed previously (Section 6.2.7.2 ). 

### 5

In the three datasets, the authors found generally positive associations between short

- term 

### 6
O 3 exposur e and all

- cause, cardiovascular, and respiratory mortality. The estimated 

### 7
excess risks for O 3 were larger for the Canadian cities than for the U.S. and European 

### 8 cities. When examining the potential confounding effects of PM 10 on O 3 mortality risk 

### 9
estimates , the sensitivity of the estimates varied across the data sets and age groups. In 

### 10 the Canadian dataset, O 3 risk estimates were modestly reduced, but remained positive, 

### 11 when adjusting for PM 10 for all

- cause mortality for all ages in the PS (4.5% [95% CI: 2. 2, 

### 12 6.7%]) and NS (4.2% [95% CI: 1.9, 6.5%]) models to 3.8% (95% CI:

- 1.4, 9.8%) and 

### 13 3.2% (95% CI:

- 2.2, 9.0%), respectively, at lag 1 for a 40 ppb increase in 1

- h max O 3 

### 14 concentrations ( Figure 6

- 29 ; Table 6

- 45 ). However, adjusting for PM 10 reduced O 3 

### 15 mortality risk estimates in the ≥ 75

- year age group, but increased the risk estimates in the 

### 16
<75

- year age group. For cardiovascular and respiratory mo rtality more variable results 

### 17
were observed with O 3 risk estimates being reduced and increased, respectively, in 

### 18 copollutant models with PM 10 ( Figure 6

- 29 ; Table 6

- 45 ). Unlike the European and U.S. 

### 19 datasets, the Canadian dataset only conducted copollutant analyses at lag 1; as a result, to 

### 20 provide a comparison across study locations only the lag 1 results are presented for the 

### 21 European and U.S. datasets in this section. 

### 22

In the European data, O 3 risk estimates were robust when adjusting for PM 10 in the year



### 23
round data for all

- cause, cardiovascular an d respiratory mortality. When restricting the 

### 24 analysis to the summer months moderate reductions were observed in O 3 risk estimates 

### 25
for all

- cause mortality with more pronounced reductions in respiratory mortality. In the 

### 26 U.S. data, adjusting for PM 10 modera tely reduced O 3 risk estimates for all

- cause mortality 

### 27 in a year

- round analysis at lag 1 (e.g., both the PS and NS models were reduced from 

### 28 0.18% to 0.13%) ( Figure 6

- 29 ; Table 6

- 45 ). Similar to the European data, when 

### 29 restricting the analysis to the summer months, in the U.S. O 3 mortality risk estim ates 

### 30 were moderately reduced, but remained positive, when adjusting for PM 10 for all

- cause 

### 31 mortality. However, when examining cause

- specific mortality risk estimates, consistent 

### 32 with the results from the Canadian dataset, which employed a similar PM sampli ng 

### 33 strategy (i.e., every

- 6th

- day sampling), O 3 risk estimates for cardiovascular and 

### 34 respiratory mortality were more variable (i.e., reduced or increased in all

- year and 

### 35 summer analyses). Overall, the estimated O 3 risks appeared to be moderately to 

### 36
substan tially sensitive to inclusion of PM 10 in copollutant models. Despite the multicity 

### 37

### Draft

– Do Not Cite or Quote 6

- 240 June 2012 approach, the mostly every

- 6th

- day sampling schedule for PM 10 in the Canadian and U.S. 

### 1 datasets greatly reduced the sample size and limits the interpretation of these results. 

### 2

Note: Effect estimates are for a 40 ppb increase in 1

- h max O 3 concentrations at lag 1. All estimates are for the 8 df/year model with nat ural splines. Circles represent all

- year analysis results while diamonds represent summer season analysis results. Open circles and diamonds represent copollutant models with PM 10 . Black = all

- cause mortality; red = cardiovascular mortality; and blue = res piratory mortality.

a Risk estimates from APHENA

- Canada standardized to an approximate IQR of 5.1 ppb for a 1

- h max increase in O 3 concentrations (see explanation in Section 6.2.7.2 ).


### Figure 6

- 29 Percent increase in all

- cause (nonaccidental) and cause

- specific mortality from natural spline models with 8 df/yr from the APHENA study for single

- and copollut ant models. All

- Year

Summer

All

- Year

Summer

All

- Year

Summer

All

- Year

All

- Year

Summer

All

- Year

Summer

All

- Year

Summer Ages

All

≥75

<75

≥75

<75

All

All

≥75

<75

All

All

≥75

<75

≥75

<75

All Location

APHENA

- U.S.

APHENA

- Canada

APHENA

- Europe All

- Cause

Cardiovascular

Respiratory

All

- Cause

Cardiovascular

Respiratory

All

- Cause

Cardiovascular

Respiratory ► ◄

◄ a

a

a

a

a

a

a

a

- 10

- 5 0 5 10 15 20 25 30 % Increase

### Draft

– Do Not Cite or Quote 6

- 241 June 2012 Table 6

- 45 Corresponding effect estimates for Figure 6

- 29.

Location * Mortality Ages Season Copollutant % Increase (95% CI)

APHENA

- U.S. All

- Cause All All

- year 1.42 (0.08, 2.78)

PM 10 1.02 (

- 1.40, 3.50)

Summer 4.31 (2.22, 6.45)

PM 10 1.90 (

- 0.78, 4.64)

Cardiovascular ≥ 75 All

- year 1.10 (

- 1.33, 3.67)

PM 10 0.47 (

- 4.61, 5.79)

<75 All

- year
- 0.16 (

- 3.02, 2.86)

PM 10 1.34 (

- 3.63, 6.61)

≥ 75 Summer 3.58 (0.87, 6.37)

PM 10 - 1.17 (

- 6.18, 4.07)

<75 Summer 3.18 (0.31, 6.12)

PM 10 1.26 (

- 4.46, 7.28) Respiratory All All

- year 2.46 (

- 1.87, 6.86)

PM 10 3.50 (

- 4.23, 11.8)

Summer 6.04 (1.18, 11.1)

PM 10 7.03 (

- 3.48, 18.5)
APHENA

- Canada All

- Cause All All

- year 4.15 (1.90, 6.45) 0.52 (0.24, 0.80) a

PM 10 3.18 (

- 2.18, 8.96)

PM 10 0.40 (

- 0.28, 1.10) a

Cardiovascular ≥ 75 All

- year 5.62 (0.95, 10.7) 0.70 (0.12, 1.30)a

PM 10 1.90 (

- 9.03, 14.1)

PM 10 0.24 (

- 1.20, 1.70) a

<75 All

- year 1.10 (

- 4.08, 6.61) 0.14 (

- 0.53, 0.82) a

PM 10 - 2.64 (

- 14.7, 11.5)

PM 10 - 0.34 (

- 2.00, 1.40) a
Respiratory All All

- year 0.87 (

- 6.40, 8.96) 0.11 (

- 0.84, 1.10) a

PM 10 22.3 (

- 12.6, 71.3)

PM 10 2.60 (

- 1.70, 7.10) a

### Draft

– Do Not Cite or Quote 6

- 242 June 2012 Location* Mortality Ages Season Copollutant % Increase (95% CI)

APHENA

- Europe All

- Cause All All

- year 1.02 (0.39, 1.66)

PM 10 1.26 (0.47, 1.98)

Summer 2.06 (1.10, 2.94)

PM 10 1.26 (0.16, 2.30)

Cardiovascular ≥ 75 All

- year 1.10 (

- 0.47, 2.70)

PM 10 1.18 (

- 0.55, 2.94)

<75 All

- year 1.34 (

- 0.24, 2.94)

PM 10 1.74 (

- 0.31, 3.75)

≥ 75 Summer 2.54 (0.39, 4.80)

PM 10 1.58 (

- 0.70, 3.99)

<75 Summer 1.66 (

- 0.70, 4.15)

PM 10 1.66 (

- 1.02, 4.40) Respiratory All All

- year 1.42 (

- 1.02, 3.83)

PM 10 1.42 (

- 1.02, 3.83)

Summer 4.31 (1.66, 7.11)

PM 10 1.18 (

- 1.79, 4.31)

*Effect estimates from Figure 6

- 29

.
a Risk estimates from APHENA

- Canada standardized to an approximate IQR of 5.1 ppb for a 1

- h max increase in O 3 concentrations (see explanation in Section 6.2.7.2 ).

Stafoggia et al. (2010 ) examined the potential confounding effects of PM 10 on the 

### 1
O 3 - mortality relationship in individuals 35 years of age and older in 10 Italian cities from 

### 2
2001 to 2005. In a time

- stratified case

- crossover analysis, using data for the summer 

### 3 months (i.e., April

- Septembe r), the authors examined O 3 - mortality associations across 

### 4 each city, and then obtained a pooled estimate through a random

- effects meta

- analysis. 

### 5 Stafoggia et al. (2010 ) found a strong association with nonaccidental mortality (9.2% 

### 6 [95% CI: 5.4, 13.0%] for a 30 ppb increase in 8

- h max O 3 concentrations) in an 

### 7 unconstrained distributed lag model (lag 0

- 5) that persisted in copollutant models with 

### 8
PM 10 (9.2 % [95% CI: 5.4, 13.7%]). Additionally, when examining cause

- specific 

### 9 mortality, the authors found positive associations between short

- term O 3 exposure and 

### 10 cardiovascular (14.3% [95% CI: 6.7, 22.4%]), cerebrovascular (8.5% [95% CI: 0.1, 

### 11 16.3%]), and respira tory (17.6% [95% CI: 1.8, 35.6%]) mortality in single

- pollutant 

### 12 models. In copollutant models, O 3 - mortality effect estimates for cardiovascular and 

### 13 cerebrovascular mortality were robust to the inclusion of PM 10 (9.2% [95% CI: 5.4, 

### 14 13.7%]) and 7.3% [95% CI:

- 1.2, 16.3%], respectively), and attenuated, but remained 

### 15 positive, for respiratory mortality (9.2% [95% CI:

- 6.9, 28.8%]). Of note, the correlations 

### 16
between O 3 and PM 10 across cities were found to be generally low, ranging from (

- 0.03 to 

### 17 0.49). The authors do not specify the sampling strategy used for PM 10 in this analysis. 

### 18

### Draft

– Do Not Cite or Quote 6

- 243 June 2012 Confounding by Seasonal Trend

The APHENA study ( Katsouyanni et al., 2009 ) , mentioned above, also conducted 

### 1 extensive sensitivity analyses to ide ntify the appropriate: (1) smoothing method and basis 

### 2 functions to estimate smooth functions of time in city

- specific models; and (2) degrees of 

### 3 freedom to be used in the smooth functions of time, to adjust for seasonal trends. Because 

### 4
O 3 peaks in the summ er and mortality peaks in the winter, not adjusting or not 

### 5 sufficiently adjusting for the seasonal trend would result in an apparent negative 

### 6
association between the O 3 and mortality time

- series. Katsouyanni et al. (2009 ) examined 

### 7 the effect of the extent of smoothing for seasonal trends by using models with 3 df/year, 

### 8
8 df/year (the choice for their main model), 12 df/year, and df/year selected using the sum 

### 9 of absolute values of partial autocorrelation func tion of the model residuals (PACF) 

### 10 (i.e., choosing the degrees of freedom that minimizes positive and negative 

### 11 autocorrelations in the residuals). Table 6

- 46 presents the results of the degrees of 

### 12 freedom analysis using alternative methods to calculate a combined estimate: the Berkey 

### 13 et al. (1998 ) meta

- regression and the two

- level normal independent sampling estimation 

### 14 (TLNISE) hierarchical method . The results show that the methods used to combine 

### 15 single

- city estimates did not influence the overall results, and that neither 3 df/year nor 

### 16 choosing the df/year by minimizing the sum of absolute values of PACF of regression 

### 17
residuals was sufficient to adjust for the seasonal negative relationship between O 3 and 

### 18 mortality. However, it should be noted, the majority of studies in the literature that 

### 19 examined the mortality effects of short

- term O 3 exposure, particularly the multicity 

### 20 studies, used 7 or 8 df /year to adjust for seasonal trends, and in both methods a positive 

### 21
association was observed between O 3 exposure and mortality. 

### 22

### Draft

– Do Not Cite or Quote 6

- 244 June 2012 Table 6

- 46 Sensitivity of ozone risk estimates per 10 μg/m 3 

### increase in 24

- h average ozone concentrations at lag 0

- 1 to alternative methods for adjustment of seasonal trend, for all

- cause mortality using Berkey MLE and TLNISE Hierarchical Models.

Seasonality Control Berkey TLNISE

3 df/year

- 0.54 (

- 0.88, 0.20)

- 0.55 (

- 0.88,

- 0.22 )

8 df/year 0.30 (0.11, 0.50) 0.31 (0.09, 0.52)

12 df/year 0.34 (0.15, 0.53) 0.33 (0.12, 0.54)

PACF

- 0.62 (

- 1.01,

- 0.22)

- 0.62 (

- 0.98,

- 0.27)
Source: Reprinted with permission of Health Effects Institute ( Katso uyanni et al., 2009 )

.



### 6.6.2.2 Effect Modification

There have been several multicity studies that examined potential effect modifiers , or 

### 1
time

- invariant factors, which may modify O 3 mortality risk estimates. These effect 

### 2 modifiers can be categorized into either individual

- level or community

- level 

### 3
characteristics , which are traditionally examined in second stage regression model s

. The 

### 4 results from these analyses also inform upon whether certain populations are greater risk 

### 5
of an O 3 - related health effects ( Chapter 8 ). In addition to potentially modifying the 

### 6
association between short

- term O 3 exposure and mortality, b oth individual

- level and 

### 7 community

- level ch aracteristics may contribute to the geographic pattern of spatial 

### 8 heterogeneity in O 3 mortality risk estimates. As a result, the geographic pattern of O 3 

### 9 mortality risk estimates is also evaluated in this section

. 

### 10

Individual

- Level Characteristics

Medina

- Ramón and Schwartz (2008 ) conducted a case

- only study in 48 U.S. cities to 

### 11 identify populations potentially at increased risk to O 3 - related mortality for the period 

### 12
1989

- 2000 (May through September of each year [i.e., warm season]). A case

- only 

### 13 design predicts the occurrence of ti me

- invariant characteristics among cases as a function 

### 14 of the exposure level ( Armstrong, 2003 ) . For each potential effect modifier 

### 15 (time

- invariant individual

- level characteristics), city

- specific logistic regression models 

### 16 were fitted, and the estimates were pooled across all cities. Furthermore, the authors 

### 17 examined potential differences in individual effect modifiers according to several city 

### 18 characteristics (e.g., mean O 3 level, mean temperature, households with central air 

### 19 conditioning, and population density) in a meta

- regression. Across cities, the authors 

### 20 found a 1.96% (95% CI: 1.14

- 2.82%) increase in mortality at lag 0

- 2 for a 30 pp b 

### 21
increase in 8

- h max O 3 concentrations. Additionally, Medina

- Ramón and Schwartz 

### 22

### Draft

– Do Not Cite or Quote 6

- 245 June 2012 (2008 ) examined a number of indi vidual

- level characteristics (e.g., age, race) and chronic 

### 1 conditions (e.g., secondary causes of death) as effect modifiers of the association between 

### 2
short

- term O 3 exposure and mortality. The authors found that older adults (i.e., ≥ 65), 

### 3
women >60 years o f age, black race, and secondary atrial fibrillation showed the greatest 

### 4 additional percent change in O 3 - related mortality ( Table 6

- 47 ). When examinin g city



### 5 level characteristics, the authors found that older adults, black race, and secondary atrial 

### 6 fibrillation had a larger effect on O 3 mortality risk estimates in cities with lower mean O 3 

### 7 concentrations. Of note, a similar case

- only study ( Schwartz, 2005b ) examined potential 

### 8 effect modifiers of the association between temperature and mortality, which would be 

### 9 expected to find results consistent with the Medina

- Ramón and Schwartz (2008 ) study 

### 10 due to the high correlation between temperature and O 3 . However, when stratifying days 

### 11 by temperature Schwartz (2005b ) found strong evidence that diabetes modified the 

### 12 temperature

- mortality association on hot days, which was not as evident when examining 

### 13
the O 3 - mortality association in Medina

- Ramón and Schwartz (2008 ) . This difference 

### 14 could be due to the study design and populations included in both studies, a multicity 

### 15 study including all ages ( Medina

- Ramón and Schwartz, 2008 ) compared to a single

- city 

### 16 study of individuals ≥ 65 years of age ( Schwartz, 2005b ) . However, when examining 

### 17
results stratified by race, nonwhites were found to have higher mortality risks on both hot 

### 18 and cold days, which provide some support for the additional risk found for black race in 

### 19
Medina

- Ramón and Schwartz (2008 )

. 

### 20

Individual

- level factors that may result in increased risk of O 3 - related mortality were also 

### 21 examined by Stafoggia et al. (2010 ) . As discussed above, using a time

- stratified case



### 22 crossover analysis, the authors found an association between short

- term O 3 exposure and 

### 23 nonaccidental mortality in an unconstrained distributed lag model in 10 Italian cities 

### 24 (9.2% [95% CI: 5.4, 13.0%; lag 0

- 5 for a 30 ppb increase in 8

- h max O 3 concentrations). 

### 25 Stafoggia et al. (2010 ) conduct ed additional analyses to examine whether age, sex, 

### 26 income level, location of death, and underlying chronic conditions increased the risk of 

### 27
O 3 - related mortality, but data were only available for nine of the cities for these analyses. 

### 28
Of the individual

- lev el factors examined, the authors found the strongest evidence for 

### 29
increased risk of O 3 - related mortality in individuals ≥ 85 years of age (22.4% [95% CI: 

### 30 15.0, 30.2%]), women (13.7% [95% CI: 8.5, 19.7%]), and out

- of

- hospital deaths (13.0% 

### 31 [95% CI: 6.0, 20. 4%]). When focusing specifically on out

- of hospital deaths and the 

### 32 subset of individuals with chronic conditions, Stafoggia et al. (2010 ) found the str ongest 

### 33 association for individuals with diabetes, which is consistent with the potentially 

### 34
increased risk of diabetics on hot days observed in Schwartz (2005b )

. 

### 35

### Draft

– Do Not Cite or Quote 6

- 246 June 2012 Table 6

- 47 Additional percent change in ozone

- related mortality for individual

level characteristics.

Percentage (95% CI)

Socio

- demographic characteristics

Age 65 yr or older 1.10 0.44
, 1.77

Women 0.58 0.18
, 0.98

Women <60 yr old b

- 0.09

- 0.76
, 0.58

Women ≥ 60 yr old b 0.60 0.25
, 0.96

Black race 0.53 0.19
, 0.87

Low education

- 0.29

- 0.81
, 0.23 Chronic conditions (listed as secondary cause)

Respiratory system diseases

Asthma 1.35

- 0.31
, 3.03

COPD 0.01

- 0.49
, 0.52 Circulatory system diseases

Atherosclerosis

- 0.72

- 1.89
, 0.45

Atherosclerotic CVD 0.74

- 0.86
, 2.37

Atherosclerotic heart disease

- 0.38

- 1.70
, 0.96 Congestive heart disease

- 0.04

- 0.39
, 0.30

Atrial fibrillation 1.66 0.03
, 3.32

Stroke 0.17

- 0.28
, 0.62
Other diseases

Diabetes 0.19

- 0.46
, 0.84 Inflammatory diseases 0.18

- 1.09
, 1.46

a These estimates represent the additional percent change in mortality for persons who had the characteristic being examined co mpared to persons who did not have the characteristic, when the mean O 3 level of the previous 3 days in creased 10 ppb. These values were not standardized because they do not represent the actual effect estimate for the characteristic being evaluated, but instead, the difference between effect estimates for persons with versus without the condition. b Compare d with males in the same age group. Source: Reprinted with permission of Lippincott Williams & Wilkins ( Medina

- Ramón and Schwartz, 2008 )

.

Additionally, Cakmak et al. (2011 ) examined the effect of individual

- level characteristics 

### 1 that may modify the O 3 - mortality relationship in 7 Chilean cities. In a time

- series analysis 

### 2 using a constrained distributed lag of 0

- 6 days, Cakmak et al. (2011 ) found evidence for 

### 3 larger O 3 mortality effects in individuals >75 years of age compared to younger ages, 

### 4
which is similar t o Medina

- Ramón and Schwartz (2008 ) and Stafoggia et al. (2010 )

. 

### 5
Unlike the studies discussed above O 3 - mortality risk estimates were found to be slightly 

### 6 larger in males (3.71% [95% CI: 0.79, 6.66] for a 40 ppb increase in max 8

- h avg O 3 

### 7 concentrations), but were n ot significa ntly different than those observed for females 

### 8 (3.00% [95% CI: 0.43, 5.68]). The major focus of Cakmak et al. (2011 ) is the 

### 9

### Draft

– Do Not Cite or Quote 6

- 247 June 2012 examination of the influence of SES indicators (i.e., educational attainment, income level, 

### 1 and employment status) on the O 3 - mortality relationship. The authors found the largest 

### 2
risk estimates in the lowest SES categories for each of the indicators examined this 

### 3 includes: primary school not completed when examining educational attainment; the 

### 4 lowest quartile of income level; and unemployed individuals when comparing 

### 5 employment status. 

### 6

Overall, uncertainties exist in the interpretation of the potential effect modifiers identified 

### 7
in Medina

- Ramón and Schwartz (2008 )
, Stafoggia et al. (2010 ) , and Cakmak et al. (2011 ) 

### 8
of the O 3 - mortality relationship due to the heterogeneity in O 3 - mortality risk estimates 

### 9 across cities as highlighted in Smith et al. (2009b ) ( Figure 6

- 27 ) and Franklin and 

### 10 Schwartz (2008 ) ( Figure 6

- 28 ). In addition, it is likely that individual

- level factors 

### 11
identified in Medina

- Ramón and Schwartz (2008 )
, ( Stafoggia et al., 2010 ) , and Cakmak 

### 12 et al. (2011 ) only modify the O 3 - mortality relationship and do not entirely explain the 

### 13 observed regional heterogeneity in O 3 - mortality risk estimates. 

### 14

Community

- level Characteristics

Several studies also examined city

- level (i.e., ecological) variables in an attempt to 

### 15 explain the observed city

- to

- city variation in estimated O 3 - mortality risk estimates. Bell 

### 16 and Dominici (2008 ) investigated whether community

- level characteristics, such as race, 

### 17 income, education, urbanization, transportation use, PM and O 3 concentrations, number 

### 18
of O 3 monitors, weat her, and air conditioning use could explain the heterogeneity in 

### 19
O 3 - mortality risk estimates across cities. The authors analyzed 98 U.S. urban 

### 20 communities from NMMAPS for the period 1987

- 2000. In the all

- year regression model 

### 21 that included no community

- lev el variables, a 20 ppb increase in 24

- h avg O 3 

### 22 concentrations during the previous week was associated with a 1.04% (95% CI: 0.56, 

### 23 1.55) increase in mortality. Bell and Dominici (2008 ) found that higher O 3 - mortality 

### 24 effect estimates were associated with an increase in: percent unemployment, fraction of 

### 25 the population Black/African

- American, percent of the population that take public 

### 26 transportation to work; and with a reduction in: temperatures and percent of households 

### 27 with central air conditioning ( Figure 6

- 30 ). The modification of O 3 - mortality risk 

### 28 estimates reported for city

- specific temperature and prevalence of central air conditioning 

### 29 in this analysis confirm the result from the meta

- analyses reviewed in the 2006 O 3 

### 30 AQCD. 

### 31

The APHENA project ( Katsouyanni et al., 2009 ) examined potential effect modification 

### 32
of O 3 risk estimates in the Canadian, European, and U.S. data sets using a consistent set 

### 33 of city

- specific variables. Table 6

- 48 presents the results from all age analyses for all



### 34 cause mortality using all

- year O 3 data for the average of lag 0

- 1 day. While there are 

### 35

### Draft

– Do Not Cite or Quote 6

- 248 June 2012 several significa nt effect modifiers in the U.S. data, the results are mostly inconsistent 

### 1 with the results from the Canadian and European data sets. The positive effect 

### 2 modification by percentage unemployed and the negative effect modification by mean 

### 3 temperature (i.e., a surrogate for air conditioning rate) are consistent with the results 

### 4 reported by Bell an d Dominici (2008 ) discussed above. However, the lack of consistency 

### 5 across the data sets, even between the Canadian and U.S. data, makes it difficult to 

### 6 interpret the results. Some of these associations may be due to coincidental correlations 

### 7
with other unmeasured factors that vary regionally (e.g., mean SO 2 tend to be higher in 

### 8 the eastern U.S.). 

### 9

### Draft

– Do Not Cite or Quote 6

- 249 June 2012 Note: The size of each circle corresponds to the inverse of the standard error of the community’s maximum likelihood estimate . Risk estimates are for a 10 ppb increase in 24

- h avg ozone concentrations during the previous week. Source: Reprinted with permission of Johns Hopkins Bloomberg School of Public Health ( Bell and Dominici, 2008 )

. 

### Figure 6

- 30 Ozone mortality risk estimates and community

- specific characteristics, U.S., 1987

- 2000.

### Draft

– Do Not Cite or Quote 6

- 250 June 2012 Table 6

- 48 Percent change in all

- cause mortality, for all ages, associated with a 40ppb increase in 1

- h max ozone concentrations at Lag 0

– 1 at the 25th and 75th percentile of the center

- specific distribution of selected effect modif iers.

Canada Europe U.S.

Effect Modifier 25th Percentile Estimate (95% CI) 75th Percentile Estimate (95% CI) t Value 25th Percentile Estimate (95% CI) 75th Percentile Estimate (95% CI) t Value 25th Percentile Estimate (95% CI) 75th Percentile Estimate (95% CI) t Value

NO 2 CV 3.10 (1.90, 4.40) 3.99 (2.38, 5.62) 1.33 1.66 (0.71, 2.62) 1.34 (

- 0.08, 2.78) - 0.49 1.26 (0.47, 1.98) 0.08 (

- 0.78, 0.95) - 2.87

Mean SO 2 2.22 (0.71, 3.83) 4.72 (2.94, 6.61) 2.16 1.58 (0.47, 2.62) 1.66 (0.39, 2.86) 0.16 0.47 (

- 0.47, 1.42) 1.98 (1.10, 2.94) 2.79

O 3 CV 2.86 (0.79, 5.05) 3.50 (2.14, 4.89) 0.60 2.62 (1.50, 3.75) 1.10 (0.24, 1.98) - 2.65 0.16 (

- 0.70, 1.10) 1.50 (0.71, 2.22) 2.68

Mean NO 2 /PM 10 3.91 (2.54, 5.29) 2.54 (0.95, 4.15) - 1.58 1.74 (0.87, 2.70) 1.50 (0.47, 2.62) - 0.43

- 0.08 (

- 1.02, 0.95) 1.26 (0.47, 2.06) 2.64

Mean Temperature 2.86 (0.95, 4.72) 3.50 (2.22, 4.89) 0.83 1.58 (0.39, 2.86) 1.58 (0.31, 2.78) - 0.04 2.14 (1.34, 2.94) 0.00 (

- 0.78, 0.79) - 4.40

% ≥ 75 yr 2.22 (0.79, 3.58) 4.23 (3.02, 5.54) 2.68 1.50 (0.55, 2.46) 1.82 (0.55, 3.10) 0.52 1.02 (0.24, 1.90) 1.02 (0.31, 1.74) - 0.02

Age

standardized Mortality 2.62 (0.79, 4.48) 4.07 (2.22, 5.87) 1.14 1.10 (

- 0.16, 2.38) 1.98 (0.79, 3.26) 1.07 0.00 (

- 0.94, 0.87) 1.58 (0.87, 2.38) 3.81

% Unemployed 2.78 (1.42, 4.07) 3.75 (2.54, 4.89) 1.88 1.42 (

- 0.47, 3.34) 1.34 (

- 0.47, 3.18) - 0.07 0.16 (

- 0.78, 1.18) 1.50 (0.71, 2.30) 2.45

Source: Adapted with permission of Health Effects Institute Katsouyanni et al. (2009 )

.

Regional Pattern of Ozone

- Mortality Risk Estimates

In addition to examining whether individual

- and community

- level factors modify the 

### 1
O 3 - mortality association, studies have also examined whether these associations varied 

### 2 regionally within the U.S. Bell and Dominici (2008 ) , in the study discussed above, also 

### 3
noted that O 3 - mortality risk est imates were higher in the Northeast (1.44% [95% CI: 0.78, 

### 4 2.10%]) and Industrial Midwest (0.73% [95% CI: 0.11, 1.35%]), while null associations 

### 5 were observed in the Southwest and Urban Midwest ( Table 6

- 49 ). The regional 

### 6 heterogeneity in O 3 - mortality risk estimates was further reflected by Bell and Dominici 

### 7 (2008 ) in a map of community

- specific Bayesian O 3 - mortality risk estimates 

### 8

### Draft

– Do Not Cite or Quote 6

- 251 June 2012 ( Figure 6

- 31 ). It is worth noting that in the analysis of PM 10 using the same data set, Peng 

### 1 et al. (2005 ) also found that both the Northeast and Industrial Midwest showed 

### 2 particularly elevated effects, especially during the summer months. As mentioned above, 

### 3 although no evidence for confounding of O 3 mortality risk estimate s by PM 10 was 

### 4 observed, Bell et al. (2007 ) did find regional differences in the correlation between O 3 

### 5
and PM 10 . Thus, the heterogeneity in O 3 mortality risk estimates may need to be 

### 6
examined as a function of the correlation between PM and O 3 . 

### 7

Smith et al. (2009b ) , as discussed earlier, also examined the regional difference in O 3 

### 8 mortality risk estimates across the same seven regions and similarly found evidence for 

### 9 regional heterogeneity. In addition, Smith et al. (2009b ) constructed spatial maps of the 

### 10 risk estimates by an extension of a hierarch ical model that allows for spatial auto



### 11 correlation among the city

- specific random effects. Figure 6

- 32 presents the spatial map 

### 12
of O 3 mortality coeffi cients from the Smith et al. (2009b ) analysis that used 8

- h max O 3 

### 13 concentrations during the summer. The results from the Bell and Dominici (2008 ) 

### 14 analysis ( Figure 6

- 31 ) shows much stronger apparent heterogeneity in O 3 - mortality risk 

### 15 estimates across cities than the smoothed map from Smith et al. (2009b ) ( Figure 6

- 32 ), 

### 16 but both maps generally show larger risk estimates in the eastern region of the U.S. 

### 17

Table 6

- 49 Percentage increase in daily mortality for a 10 ppb increase in 24

- h average ozone concentrations during the previous week by geographic region in the U.S., 1987

- 2000.

No. of Communities Reg ional Estimate 95% PI* Regional results

Industrial Midwest 20 0.73 0.11, 1.35

Northeast 16 1.44 0.78, 2.10

Northwest 12 0.08

- 0.92, 1.09

S outhern California 7 0.21

- 0.46, 0.88
Southeast 26 0.38

- 0.07, 0.85

Southwest 9

- 0.06

- 0.92, 0.81

Urban Midwest 7

- 0.05

- 1.28, 1.19
National results

All continental communities 97 0.51 0.27, 076

All communities 98 0.52 0.28, 0.77 Source: Reprinted with permission of Johns Hopkins Bloomberg School of Public Health ( Bell and Dominici, 2008 )

.

### Draft

– Do Not Cite or Quote 6

- 252 June 2012 Source: Reprinted with permission of Johns Hopkins Bloomberg School of Public Health, ( Bell and Dominici, 2008 )

. 

### Figure 6

- 31 Community

- specific Bayesian o zone - mortality risk estimates in 98 U.S. communities.

Source: Reprinted with permission of Informa UK Ltd. ( Smith et al., 2009b )

. 

### Figure 6

- 32 Map of spatially dependent ozone

- mortality coefficients for 8

- h max ozone concentrations using summer data.

### Draft

– Do Not Cite or Quote 6

- 253 June 2012 6.6.2.3 Interaction

Interactions can lead to either antagonistic or synergistic effects; however, most studies 

### 1

a ttempt to identify potential factors that interact synergistically with O 3 to increase the 

### 2 risk of mortality. Within this section, interactive effects are defined as time

- varying 

### 3 covariates, such as temperature and copollutants that are included in 1st sta ge time

- series 

### 4 regression models. To date, only a few time

- series studies have investigated the potential 

### 5
interaction between O 3 exposure and copollutants or weather variables. This can be 

### 6 attributed to the moderate to high correlation between O 3 and these covariates, which 

### 7 makes such investigations methodologically challenging. 

### 8

Ren et al. (2008 ) examined the possible synergistic effect between O 3 and temperature on 

### 9 mortality in the 60 largest eastern U.S. communities from the NMMAPS data during the 

### 10 warm months (i.e., April to October) from 1987

- 2000. This analysis was restricted to the 

### 11 eastern areas of the U.S. (i.e., Northeast, Industrial Midwest and Southeast) because a 

### 12 previous study which focused specifically on the eastern U.S. found that 

### 13 temperature

- mortality patterns differ between the northeast and southeast regions 

### 14 possibly due to climatic differences ( Curriero et al., 2002 ) . To examine possible 

### 15 geographic differences in the interact ion between temperature and O 3 , Ren et al. (2008 ) 

### 16 further divided the NMMAPS regions into the Northeast, which included the Northeast 

### 17 and Industrial Midwest regions (34 cities), and the Southeast, which included the 

### 18 Southeast region (26 cities). The potential synergistic effects between O 3 and temperature 

### 19 were examined using two different models. Model 1 included an interaction term in a 

### 20 Generalized Additive Model (GAM) for O 3 and max imum temperature (3

- day avg values 

### 21 were used for both terms) to examine the bivariate response surface and the pattern of 

### 22 interaction between the two variables in each community. Model 2 consisted of a 

### 23 Generalized Linear Model (GLM) that used interaction t erms to stratify by “low,” 

### 24 “moderate,” and “high” temperature days using the first and third quartiles of temperature 

### 25

as cut

- offs to examine the percent increase in mortality in each community. Furthermore, 

### 26

a two

- stage Bayesian hierarchical model was used to estimate the overall percent increase 

### 27
in all

- cause mortality associated with short

- term O 3 exposure across temperature levels 

### 28 and each region using model 2. The same covariates were used in both model 1 and 2. 

### 29 The bivariate response surfaces from model 1 suggest possible interactive effects 

### 30
between O 3 and temperature although the interpretation of these results is not 

### 31 straightforward due to the high correlation between these terms. The apparent interaction 

### 32 between temperature and O 3 as evaluated in model 2 varied across geographic regions. In 

### 33 the northeast region, a 20 ppb increase in 24

- h avg O 3 concentrations at lag 0

- 2 was 

### 34 associated with an increase of 4.49% (95% posterior interval [PI]: 2.39, 6.36%), 6.21% 

### 35 (95% PI: 4.47, 7.66%) and 12.8% (95% PI: 9.7 7, 15.7%) in mortality at low, moderate 

### 36 and high temperature levels, respectively. The corresponding percent increases in 

### 37

### Draft

– Do Not Cite or Quote 6

- 254 June 2012 mortality in the southeast region were 2.27% (95% PI:

- 2.23, 6.46%) for low temperature, 

### 1 3.02% (95% PI: 0.44, 5.70%) for moderate temp erature, and 2.60% (95% PI:

- 0.66, 

### 2 6.01%) for high temperature. 

### 3

When examining the relationship between temperature and O 3 - related mortality, the 

### 4 results reported by Ren et al. (2008 ) (i.e., higher O 3 - mortality risks on days with higher 

### 5 temperatures) may appear to contradict the results of Bell and Dominici (2008 ) described 

### 6 earlier (i.e., communities with higher temperature have lower O 3 - mortality risk 

### 7 estimates). However, the observed difference in results can be attributed to the 

### 8 interpretation of effect modification in a second

- stage regression which uses long

- term 

### 9 average temperatures, as was performed by Bell and Dominici (2008 ) , compared to a 

### 10
first

- stage regression that examines the interaction between daily temperature and O 3 - 

### 11 related mortality. In this case, the second

- stage regression results from Bell and Dominici 

### 12 (2008 ) indicate that a city with lower temperatures, on average, tend to show a stronger 

### 13
O 3 mortality effect, whereas, in the first

- stage regression performed by Ren et al. (2008 )
, 

### 14 the days with higher temperature tend to show a larger O 3 - mortality effect. This observed 

### 15
di fference may in part reflect the higher air conditioning use in communities with higher 

### 16 long

- term average temperatures. Therefore, the findings from Ren et al. (2008 ) indicating 

### 17

gene rally lower O 3 risk estimates in the southeast region where the average temperature is 

### 18 higher than in the northeast region is consistent with the regional results reported by Bell 

### 19 and Dominici (2008 ) . As demonstrated by the results from both Ren et al. (2008 ) and 

### 20 Bell and Dominici (2008 ) caution is required when interpreting results from studies that 

### 21

e xamined interactive effects using two different approaches because potential effect 

### 22 modification as suggested in a second

- stage regression generally does not provide 

### 23
evidence for a short

- term interaction examined in a first

- stage regression. Overall, furth er 

### 24 examination of the potential interactive (synergistic) effects of O 3 and covariates in time



### 25 series regression models is required to more clearly understand the factors that may 

### 26
influence O 3 mortality risk estimates. 

### 27

6.6.2.4 Evaluation of the Ozone

- Mortality C

- R Relationship and Related Issues

Evaluation of the O 3 - mortality C

- R relationship is not straightforward because the 

### 28 evidence from multicity studies (using log

- linear models) suggests that O 3 - mortality 

### 29 associations are highly heterogeneous across regions. I n addition, there are numerous 

### 30 issues that may influence the shape of the O 3 - mortality C

- R relationship and the observed 

### 31
association between short

- term O 3 exposure and mortality that warrant examination 

### 32 including: multi

- day effects (distributed lags), mort ality displacement (i.e., hastening of 

### 33 death by a short period), potential adaptation, and the exposure metric used to compute 

### 34

### Draft

– Do Not Cite or Quote 6

- 255 June 2012 risks (e.g., 1

- hour daily max versus 24

- h avg). The following section presents the recent 

### 1
studies identified that conducted an in itial examination of these issues. 

### 2

Multiday Effects, Mortality Displacement, and Adaptation

The pattern of positive lagged associations followed by negative associations in a 

### 3 distributed lag model may be considered an indication of “mortality displacement” 

### 4 (i.e., deaths are occurring in frail individuals and exposure is only moving the day of 

### 5 death to a day slightly earlier). Zanobetti and Schwartz (2008b ) examined this issue in 48 

### 6 U.S. cities during the warm season (i.e., June

- August) for the years 1989

- 2000. In an 

### 7 initial analysis, the authors applied a GLM to examine same

- day O 3 - mortality effects, and 

### 8
in the model included an unconstrained distributed la g for apparent temperature to take 

### 9 into account the effect of temperature on the day death occurred and the previous 7 days. 

### 10 To examine mortality displacement Zanobetti and Schwartz (2008b ) refit models using 

### 11

tw o approaches: an unconstrained and a smooth distributed lag each with 21

- day lags for 

### 12
O 3 . In this study, all

- cause mortality as well as cause

- specific mortality 

### 13 (i.e., cardiovascular, respiratory, and stroke) were examined for evidence of mortality 

### 14 displac ement. The authors found a 0.96% (95% CI: 0.60, 1.30%) increase in all

- cause 

### 15 mortality across all 48 cities for a 30 ppb increase in 8

- h max O 3 concentrations at lag 0 

### 16 whereas the combined estimate of the unconstrained distributed lag model (lag 0

- 20) was 

### 17 1.54% (95% CI: 0.15, 2.91%). Similarly, when examining the cause

- specific mortality 

### 18 results ( Table 6

- 50 ), larger risk estimates were observed for the d istributed lag model 

### 19 compared to the lag 0 day estimates. However, for stroke a slightly larger effect was 

### 20 observed at lags 4

- 20 compared to lags 0

- 3 suggesting a larger window for O 3 - induced 

### 21 stroke mortality. This is further supported by the sum of lags 0 through 20 days showing 

### 22 the greatest effect. Overall, these results suggest that estimating the mortality risk using a 

### 23 single day of O 3 exposure may underestimate the public health impact, but the extent of 

### 24
multi

- day effects appear to be limited to a few days. This is further supported by the 

### 25 shape of the combined smooth distributed lag ( Figure 6

- 33 ). It should be noted that the 

### 26 proportion of total var iation in the effect estimates due to the between

- cities 

### 27 heterogeneity, as measured by I 2 statistic, was relatively low (4% for the lag 0 estimates 

### 28 and 21% for the distributed lag), but 21 out of the 48 cities exhibited null or negative 

### 29
estimates. As a res ult, the estimated shape of the distributed lag cannot be interpreted as a 

### 30 general form of lag structure of associations applicable to all the cities included in this 

### 31 analysis. 

### 32

### Draft

– Do Not Cite or Quote 6

- 256 June 2012 Table 6

- 50 Estimated effect of a 10 ppb increase in 8

- h max ozone concentrations on mortality during the summer months for single

- day and distributed lag models.

% (Percentage) 95% CI Total mortality
Lag 0 0.32 0.20
, 0.43 Sum lags 0

- 20 0.51 0.05
, 0.96 Sum lags 0

- 3 0.53 0.28
, 0.77 Sum lags 4

- 20

- 0.02

- 0.35
, 0.31 Cardiovascular mortality
Lag 0 0.47 0.30
, 0.64 Sum lags 0

- 20 0.49

- 0.01
, 1.00 Sum lags 0

- 3 0.80 0.48
, 1.13 Sum lags 4

- 20

- 0.23

- 0.67
, 0.22 Respiratory mortality
Lag 0 0.54 0.26
, 0.81 Sum lags 0

- 20 0.61

- 0.41
, 1.65 Sum lags 0

- 3 0.83 0.38
, 1.28 Sum lags 4

- 20

- 0.24

- 1.08
, 0.60
Stroke
Lag 0 0.37 0.01
, 0.74 Sum lags 0

- 20 2.20 0.76
, 3.67 Sum lags 0

- 3 0.92 0.26
, 1.59 Sum lags 4

- 20 1.26 0.05
, 2.49 Source: Reprinted with permission of American Thoracic Society, Zanobetti and Schwartz (2008b )

.

Samoli et al. (2009 ) also investigated the temporal pattern of mortality effects in response 

### 1
to short

- term exposure to O 3 in 21 European cities that were included in the APHEA2 

### 2 project. Using a metho d similar to Zanobetti and Schwartz (2008b ) , the authors applied 

### 3 unconstrained distributed lag models with lags up to 21 days in each city during the 

### 4 summer months (i.e., June through A ugust) to examine the effect of O 3 on all

- cause, 

### 5 cardiovascular, and respiratory mortality. They also applied a generalized additive 

### 6 distributed lag model to obtain smoothed distributed lag coefficients. However, unlike 

### 7 Zanobetti and Schwartz (2008b )
, Samoli et al. (2009 ) controlled for temperature using a 

### 8 linear term for humidity and an unconstrained distributed lag model of temperature at 

### 9 lags 0

- 3 days. The choice of 0

- through 3

- day lags of temperature was based on a 

### 10 previous Euro pean multicity study ( Baccini et al., 2008 ) , which suggested that summer 

### 11 temperature effec ts last only a few days. Upon combining the individual city estimates 

### 12 across cities in a second stage regression, Samoli et al. (2009 ) found that the estimated 

### 13

### Draft

– Do Not Cite or Quote 6

- 257 June 2012 effects on respiratory mortality were extended for a period of two weeks. However, for 

### 1
all

- cause and cardiovascular m ortality, the 21

- day distributed lag models yielded null or 

### 2 (non

- significa nt) negative estimates ( Table 6

- 51 ). Figure 6

- 34 shows the distributed lag 

### 3
coefficients for all

- cause mortality, which exhibit a declining trend and negative 

### 4 coefficients beyond 5

- day lags. The authors’ interpretation of these results was that 

### 5 “using single

- day exposures may have overestimated the effects on all

- cause and 

### 6 cardiovascular mortality, but underestimated the effects on respiratory mortality.” Thus, 

### 7 the results in part suggest evidence of mortality displacement for a ll

- cause and 

### 8 cardiovascular mortality. 

### 9

Source: Reprinted with permission of American Thoracic Society ( Zanobetti and Schwartz, 2008b )

. Note: The triangles represent the percent increase in all

- cause mortality for a 10 ppb increase in 8

- h max O 3 concentrations at each lag while the shaded areas are the 95% point

- wise confidence intervals.


### Figure 6

- 33 Estimated combined smooth distributed lag for 48 U.S. cities during the summer months.

### Draft

– Do Not Cite or Quote 6

- 258 June 2012 Table 6

- 51 Estimated percent increase in cause

- specific mortality (and 95% CIs) for a 10

- μg/m 3 

### increase in maximum 8

- hour ozone during June

- August.

Fixed effects % (95% CI) R andom effects % (95% CI) Total mortality a
Lag 0 0.28 (0.11, 0.45) 0.28 (0.07, 0.48) Average lags 0

- 1 0.24 (0.15, 0.34) 0.22 (0.08, 0.35) Sum lags 0

- 20, unconstrained 0.01 (

- 0.40, 0.41)

- 0.54 (

- 1.28, 0.20) Sum lags 0

- 20, penalized 0.01 (

- 0.41, 0.42)

- 0.56 (

- 1.30, 0.19) Cardiovascular mortality a
Lag 0 0.43 (0.18, 0.69) 0.37 (0.05, 0.69) Average lags 0

- 1 0.33 (0.19, 0.48) 0.25 (0.03, 0.47) Sum lags 0

- 20, unconstrained

- 0.33 (

- 0.93, 0.29)

- 0.62 (

- 1.47, 0.24) Sum lags 0

- 20, penalized

- 0.32 (

- 0.92, 0.28)

- 0.57 (

- 1.39, 0.26) Respiratory mortality a
Lag 0 0.36 (

- 0.21, 0.94) 0.36 (

- 0.21, 0.94) Average lags 0

- 1 0.40 (0.11, 0.70) 0.40 (0.11, 0.70) Sum lags 0

- 20, unconstrained 3.35 (1.90, 4.83) 3.35 (1.90, 4.83) Sum lags 0

- 20, penalized 3.66 (2.25, 5.08) 3.66 (2.25, 5.08)

a Analysis for the same day (lag 0), the average of the same and previous day (lag 0

- 1), the unconstrained distributed lag model for the sum of 0

- 20 days and the penalized distributed lag model (lag 0

- 20) Source: Used with permissio n of BMJ Group ( Samoli et al., 2009 )

.

Although the APHENA project ( Katsouyanni et al., 2009 ) did not specifically investigate 

### 1 mortality displacement and therefore did not consider longer lags (e.g., lag >3 days), the 

### 2 study did present O 3 risk estimates fo r lag 0

- 1, lag 1, and a distributed lag model of 0

- 

### 3
2 days in the Canadian, European, and U.S. datasets. Katsouyanni et al. (2009 ) found that 

### 4 the results vary somewhat across the regions, but, in general, the re was no indication that 

### 5 the distributed lag model with up to a 2

- day lag yielded meaningfully larger O 3 mortality 

### 6 risk estimates than the lag 0

- 1 and lag 1 results. For example, for all

- cause mortality, 

### 7 using the model with natural splines and 8 df/year to adjust for seasonal trends, the 

### 8 reported percent excess risk for mortality for a 40 ppb increase in 1

- h max O 3 

### 9 concentrations for lag 0

- 1, lag 1, and the distributed lag model (lag 0

- 2) was 2.70% 

### 10 (95% CI: 1.02, 4.40%), 1.42% (95% CI: 0.08, 2.78%), and 3 .02% (95% CI: 1.10, 4.89%), 

### 11 respectively. Thus, the observed associations appear to occur over a short time period, 

### 12 (i.e., a few days). Similarly, the Public Health and Air Pollution in Asia (PAPA) study 

### 13 ( Wong et al., 2010 ) also examined multiple lag days (i.e., lag 0, lag 0

- 1, and lag 0

- 4), and 

### 14 although it did not specifically examine mortality displacement it does provide additional 

### 15 evidence regarding the timing of mortality effects proceeding O 3 exposure. In a combined 

### 16

### Draft

– Do Not Cite or Quote 6

- 259 June 2012 analysis using data from all four cities examined (Bangkok, H ong Kong, Shanghai, and 

### 1 Wuhan), excess risk estimates at lag 0

- 4 were larger than those at lag 0 or lag 0

- 1 in both 

### 2 fixed and random effect models (results not presented quantitatively). The larger risk 

### 3 estimates at lag 0

- 4 can primarily be attributed to t he strong associations observed in 

### 4 Bangkok and Shanghai. However, it is worth noting that Bangkok differs from the three 

### 5 Chinese cities included in this analysis in that it has a tropical climate and does not 

### 6 exhibit seasonal patterns of mortality. As a re sult, Wong et al. (2010 ) examined the O 3 - 

### 7 mortality associations at lag 0

- 1 in only the three Chinese cities and found that risk 

### 8 estimates were slightly reduced from 2.26% (95% CI: 1.36, 3.16) in the 4 city analysis to 

### 9 1.84% (0.77, 2.86) in the 3 city analysis for a 30 ppb increase in 8

- h max O 3 

### 10 concentrations. Overall, the PAPA study further supports the observation of the 

### 11 APHENA study that associations between O 3 and mortality occur over a relatively short



### 12 time period, but also indicates that it may be difficult to interpret O 3 - mortality 

### 13 associations across cities with different climates and mortality patterns. 

### 14

When comparing the studies that explicitly examined the potential for mortality 

### 15 displacement in the O 3 - mortality relationship, the results from Samoli et al. (2009 ) , which 

### 16 provide evidence that suggests mortality displacement, are not consistent with those 

### 17 reported by Zanobetti and Schwartz (2008b ) . However, the shapes of the estimated 

### 18 smooth distributed lag associations are similar ( Figure 6

- 33 and Figure 6

- 34 ). A closer 

### 19
examinat ion of these figures shows that in the European data beyond a lag of 5 days the 

### 20 estimates remain negative whereas in the U.S. data the results remain near zero for the 

### 21 corresponding lags. These observed difference could be due to the differences in the 

### 22
mod el specification between the two studies, specifically the use of: an unconstrained 

### 23 distributed lag model for apparent temperature up to 7 previous days ( Zanobetti and 

### 24 Schwartz, 2008b ) versus a linear term for humidity and an unconstrained distributed lag 

### 25 model of temperature up to 3 previous days ( Samoli et al., 2009 ) ; and natural cubic 

### 26 splines with 2 df per season ( Zanobetti and Schwartz, 2008b ) versus dummy variables per 

### 27 month per year to adjust for season ( Samoli et al., 2009 ) . It is important to note that these 

### 28 differences in model specification may have also influenced the city

- to

- city variation in 

### 29 risk estimates observed in these two studies (i.e., homogenous estimates across cities in 

### 30 Zanobetti and Schwartz (200 8b ) and heterogeneous estimates across cities in Samoli et 

### 31 al. (2009 ) . Overall, the evidence of mortality displacement remains unclear, but Samoli et 

### 32 al. (2009 )
, Zanobetti and Schwartz (2008b ) , and Katsou yanni et al. (2009 ) all suggest that 

### 33 the positive associations between O 3 and mortality are observed mainly in the first 

### 34
few days after exposure. 

### 35

### Draft

– Do Not Cite or Quote 6

- 260 June 2012 Note: The triangles represent the percent increase in all

- cause mortality for a 10 μg/m 3 increase in 8

- h max O 3 concentrations at each lag; the shaded area represents the 95% CIs. Source: Reprinted with permission of BMJ Group ( Samoli et al., 2009 )

. 

### Figure 6

- 34 Estimated combined smooth distributed lag in 21 European cities during the summer (June

- August) months.

Adaptation

Controlled human exposure studies have demonstrated an adaptive response to O 3 

### 1 exposure for respiratory effects, such as lung function decrements, but this issue has not 

### 2 been examined in the epidemiologic investigation of m ortality effects of O 3 . Zanobetti 

### 3 and Schwartz (2008a ) examined if there was evidence of an adaptive response in the 

### 4
O 3 - mortality relationship in 48 U.S. cities from 1989 to 2000 (i.e., the same data analyzed 

### 5
in Zanobetti and Schwartz (2008b ) . The authors examined all

- cause mortality using a 

### 6

case

- crossover design to estimate the same

- day (i.e., lag 0) effect of O 3 , matched on 

### 7 referent days from every

- 3rd

- day in the same month and year as the case. Zanobetti and 

### 8 Schwartz (2008a ) examined O 3 - mortalit y associations by: season, month in the summer 

### 9 season (i.e., May through September), and age categories in the summer season 

### 10 ( Table 6

- 52 ). The estimat ed O 3 mortality risk estimate at lag 0 was found to be highest in 

### 11 the summer (1.51% [95% CI: 1.14, 1.87%]; lag 0 for a 30 ppb increase in 8

- h max O 3 

### 12 concentrations), and, within the warm months, the association was highest in July (1.96% 

### 13

### Draft

– Do Not Cite or Quote 6

- 261 June 2012 [95% CI: 1.42, 2.4 8%]; lag 0). 1 Upon further examination of the summer months, the 

### 1 authors also observed diminished effects in August (0.84% [95% CI: 0.33, 1.39%]; lag 

### 2 0). Based on these results, the authors concluded that the mortality effects of O 3 appear 

### 3
diminished later in the O 3 season. 

### 4

Table 6

- 52 Percent excess all

- cause mortality per 10 ppb increase in daily 8

- h max ozone on the same day, by season, month, and age groups.

% 95% CI
By Season

Winter

- 0.13

- 0.56, 0.29 Spring 0.35 0.16, 0.54

Summer 0.50 0.38, 0.62

Fall 0.05

- 0.14, 0.24 By Month May 0.48 0.28, 0.68

June 0.46 0.24, 0.68 July 0.65 0.47, 0.82 August 0.28 0.11, 0.46 September

- 0.09

- 0.35, 0.16 By Age Group

0

- 20 0.08

- 0.42, 0.57

21

- 30 0.10

- 0.67, 0.87

31

- 40 0.07

- 0.38, 0.52

41

- 50 0.08

- 0.27, 0.43

51

- 60 0.54 0.19, 0.89

61

- 70 0.38 0.16, 0.61

71

- 80 0.50 0.32, 0.67

80 0.29 0.13, 0.44

Source: Zanobetti and Schwar tz (2008a )

.

To further evaluate the potential adaptive response observed in Zanobetti and Schwartz 

### 5 (2008a ) the distribution of the O 3 concentrations across the 48 U.S. cities during July and 

### 6 August was examined. Both July and August were found to have comparable means of 

### 7
48.6 and 47.9 ppb with a reported maximum value of 97.9 and 96.0 ppb, respectively. 

### 8 Thus, the observed reduction in O 3 - related mortality effect estimate s in August (0.84%) 

### 9

1 These values have been standardized to the increment used throughout the ISA for max 8

- h avg increase in O 3 concentrations of 30 ppb. These values differ from those p resented in Table 6

- 52 from Zanobetti and Schwartz (2008a ) because the authors presented values for a 10 ppb increase in max 8

- h avg O 3 concentrations.

### Draft

– Do Not Cite or Quote 6

- 262 June 2012 compared to July (1.96%) appears to support the existence of an adaptive response. 

### 1 However, unlike an individual’s adaptive response to decrements in lung function from 

### 2
short

- term O 3 exposure, an examination of mortality prevents a dire ct observation of 

### 3 adaptation. Rather, for mortality the adaptation hypothesis is tested with a tacit 

### 4 assumption that, whatever the mechanism for O 3 - induced mortality, the risk of death 

### 5
from short

- term O 3 exposure is reduced over the course of the summer mo nths through 

### 6 repeated exposures. This idea would translate to a smaller population that would die from 

### 7
O 3 exposure towards the end of summer. This may complicate the interpretation of the 

### 8 distributed lag coefficients with long lag periods because the decre ased coefficients may 

### 9 reflect diminished effects of the late summer, rather than diminished effects that are 

### 10 constant across the summer. These intertwined issues need to be investigated together in 

### 11
future research. 

### 12

Exposure Metric

When examining the assoc iation between short

- term O 3 exposure and mortality it is also 

### 13 important to consider the exposure metric used (i.e., 24

- h avg, 8

- h max, and 1

- h max). To 

### 14 date, only a few studies have conducted analyses to examine the impact of different 

### 15 exposure metrics on O 3 mortality risk estimates. In Smith et al. (2009b ) , the authors 

### 16 examined the effect of different exposure metrics (i.e., 24

- h avg , 8

- h max, and 1

- h max) 

### 17
on O 3 - mortality regression coefficients. When examining whether there are differences in 

### 18 city

- specific risk estimates when using different exposure metrics, Smith et al. (2009b ) 

### 19 found a rather high correlation (r = 0.7

- 0.8) between risk estimates calculated using 

### 20
24

- h avg versus 8

- h max and 1

- h max versus 8

- h max averaging times. These results are 

### 21
consistent with the correlations reported by Darrow et al. (2011a ) (Section 6.2.7.3 ) 

### 22
between the 8

- h max and 24

- avg exposure metrics. 

### 23

In addition to these recent studies published since the 2006 O 3 AQCD, Gryparis et al. 

### 24 (2004 ) also supports the high correlation between 1

- h max and 8

- h max O 3 

### 25 concentrations reported in Smith et al. (2009b ) and Darrow et al. (2011a ) and the 

### 26 subsequent high degree of similarity between mortality risk estimates calculated using 

### 27
either metric. Although only a limited number of studies have examined the effect of 

### 28 different exposure metrics on O 3 - mortality risk estimates, these studies suggest relatively 

### 29 comparable results across the exposure metrics used. 

### 30

Ozone

- Mortality C

- R Relationship and Threshold Analyses

Several of the recent studies evaluated have applied a variety of statistical approaches to 

### 31 examine the shape of the O 3 - mortality C

- R relationship and whether a threshold exists. 

### 32 The approach used by Bell et al. (2006 ) consisted of applying four statistical models to 

### 33

### Draft

– Do Not Cite or Quote 6

- 263 June 2012 the NMMAPS data, which included 98 U.S. communities for the period 1987

- 2000. 

### 1 These models included: a linear analysis (i.e., any change in O 3 concentration can be 

### 2
associ ated with mortality) (Model 1); a subset analysis (i.e., examining O 3 - mortality 

### 3 relationship below a specific 24

- avg concentration, ranging from 5 to 60 ppb) (Model 2); 

### 4 a threshold analysis (i.e., assuming that an association between O 3 and mortality is 

### 5 observed above a specific concentration and not below it, using the threshold values set at 

### 6
an increment of 5 ppb between 0 to 60 ppb and evaluating a presence of a local minima in 

### 7 AICs computed at each increment) (Model 3); and nonlinear models using natural cubic 

### 8 splines with boundary knots placed at 0 and 80 ppb, and interior knots placed at 20 and 

### 9
40 ppb (Model 4). A two

- stage Bayesian hierarchical model was used to examine these 

### 10
models and O 3 - mortality risk estimates at the city

- level in the first stage analysis and 

### 11 aggregate estimates across cities in the 2nd stage analysis using the average of 0

- and 

### 12
1

- day lagged 24

- h avg O 3 concentrations. The results from all of these models suggest 

### 13
that if a threshold exists it does so well below the current O 3 NAAQS. When restricting 

### 14 the analysis to all days when the 1997 O 3 NAAQS 8

- hour standard (i.e., 84 ppb daily 

### 15
8

- h max) is met in each community, Bell et al. (2006 ) found there was still a 0.60% (95% 

### 16 PI: 0.30, 0.90%) increase in mortality per 20 ppb increase in 24

- h avg O 3 concentrations 

### 17 at lag 0

- 1. Figure 6

- 35 shows the combined C

- R curve ob tained using the nonlinear 

### 18 model (Model 4). Although these results suggest the lack of threshold in the O 3 - mortality 

### 19 relationship, it is difficult to interpret such a curve because: (1) there is uncertainty 

### 20 around the shape of the C

- R curve at 24

- h avg O 3 concentrations generally below 20 ppb, 

### 21 and (2) the C

- R curve does not take into consideration the heterogeneity in O 3 - mortality 

### 22
risk estimates across cities. 

### 23

### Draft

– Do Not Cite or Quote 6

- 2 64 June 2012 Source: Bell et al. (2006 )


### Figure 6

- 35 Estimated combined C

- R curve for nonaccidental mortality and 24

- hour average ozone concentrations at lag 0

- 1 using the nonlinear (spline) model.

Using the same NMMAPS dataset as Bell et al. (2006 )
, Smith et al. (2009b ) further 

### 1
examined the O 3 - mortality C

- R relationship. Similar to Bell et al. (2006 )
, Smith et al. 

### 2 (2009b ) conduct a subset analysis, but instead of restrict ing the analysis to days with O 3 

### 3 concentrations below a cutoff the authors only include days above a defined cutoff in the 

### 4 analysis. The results of this “reversed subset” approach are in line with those reported by 

### 5 Bell et al. (2006 ) ; consistent positive associations at all cutoff points up to a defined 

### 6 concentration where the total number of days with 24

- h avg O 3 concentrations above a 

### 7 value are so limited that the variability around the central estimate is increased. In the 

### 8 Smith et al. (2009b ) analysis this observation was initially observed at 45 ppb, with the 

### 9 largest variability at 60 ppb; however, unlike Bell et al. (2006 ) where 73% of days are 

### 10 excluded when subsetting the data to less than 2 0 ppb, the authors do not detail the 

### 11 number of days of data included in the subset analyses at higher concentrations. In 

### 12 addition to the subset analysis, Smith et al. (2009b ) examined the shape of the C

- R curve 

### 13 using a piecewise linear approach with cutpoints at 8

- h avg concentrations of 40 ppb, 

### 14
60 ppb, and 80 ppb. Smith et al. (2009b ) found that the shape of the C

- R curve is similar 

### 15

### Draft

– Do Not Cite or Quote 6

- 265 June 2012 to that reported by Bell et al. (2006 ) ( Figure 6

- 35 ), but argue that slopes of the β for each 

### 1 piece of the curve are highly variable with the largest variation in the 60

- 80 ppb range. 

### 2 However, the larger variability around the β between 60

- 80 would be expected due to the 

### 3 small number of days with O 3 concentrations within that range in an all

- year analysis. 

### 4 This result is consistent with that observed by Bell et al. (2006 ) , which is presented in 

### 5 Figure 6

- 35

. 

### 6

The APHENA project ( Katsouyanni et al., 2009 ) also analyzed the Canadian and 

### 7 European datasets (the U.S. data were analyzed for PM 10 only) for evidence of a 

### 8 threshold, using the threshold analysis method (Model 3) applied in Bell et al. (2006 ) 

### 9 study described above. There was no evidence of a thresho ld in the Canadian data 

### 10 (i.e., the pattern of AIC values for each increment of a potential threshold value varied 

### 11 across cities, most of which showed no local minima). Likewise, the threshold analysis 

### 12 conducted using the European data also showed no eviden ce of a threshold. 

### 13

The PAPA study, did not examine whether a threshold exists in the O 3 - mortality C

- R 

### 14 relationship, but instead the shape of the C

- R curve individually for each city (Bangkok, 

### 15 Hong Kong, Shanghai, and Wuhan) ( Wong et al., 2010 ) . Using a natural spline smoother 

### 16
with 3df for the O 3 term, Wong et al. (2010 ) examined whether non

- linearity was present 

### 17 by testing the change in deviance between the smoothed, non

- linear, model and an 

### 18 unsmoothed, linear, model with 1 df. For each of the cities, both across the full range of 

### 19
the O 3 distrib ution and specifically within the range of the 25th to 75th percentile of each 

### 20 city’s O 3 24

- h avg concentrations (i.e., a range of 9.7 ppb to 60.4 ppb across the cities) 

### 21
there was no evidence of a non

- linear relationship in the O 3 - mortality C

- R curve. It 

### 22 should be noted that the range of the 25th to 75th percentiles in all of the cities, except 

### 23 Wuhan, was lower than that observed in the U.S. using all

- year data where the range 

### 24 from the 25th to 75th percentiles is 30 ppb to 50 ppb ( Table 3

- 6 ). 

### 25

Additional threshold analyses were conducted using NMMAPS data, by Xia and Tong 

### 26 (2006 ) and Stylianou and Nicolich (2009 ) . Both studies used a new statistical approach 

### 27 developed by Xia and Tong (2006 ) to examine thresholds in the O 3 mortality C

- R 

### 28 relationship. The approach consisted of an extended GAM model, which accounted for 

### 29 the cumulative and nonlinear effects of air pollution using a weighted cumulative sum for 

### 30 each pollutant, with the weights (non

- increasing further into the past) derived by a 

### 31 restricted minimization method. The authors did not use the term distributed lag model, 

### 32 but their model has the form of distributed lag model, except that it allows for nonlinear 

### 33 functional forms. Using NMMAP S data for 1987

- 1994 for 3 U.S. cities (Chicago, 

### 34 Pittsburgh, and El Paso), Xia and Tong (2006 ) found that the extent of cumulative effects 

### 35
of O 3 on mortality were relatively short. While the authors also note that there was 

### 36
evidence of a threshold effect around 24

- h avg concentrations of 25 ppb, the threshold 

### 37

### Draft

– Do Not Cite or Quote 6

- 266 June 2012 values estimated in the analysis were sometimes in the range where data density was low. 

### 1 Thus, this threshold analysis needs to be replicated in a larger number of cities to confir m 

### 2 this observation. It should be noted that the model used in this analysis did not include a 

### 3 smooth function of days to adjust for unmeasured temporal confounders, and instead 

### 4 adjusted for season using a temperature term. As a result, these results need t o be viewed 

### 5 with caution because some potential temporal confounders (e.g., influenza) do not always 

### 6 follow seasonal patterns of temperature. 

### 7

Stylianou and Nicolich (2009 ) examined the existence of thresholds following an 

### 8 approach similar to Xia and Tong (2006 ) for all

- cause, cardiovascular, and respiratory 

### 9

morta lity using data from NMMAPS for nine major U.S. cities (i.e., Baltimore, Chicago, 

### 10 Dallas/Fort Worth, Los Angeles, Miami, New York, Philadelphia, Pittsburgh, and 

### 11 Seattle) for the years 1987

- 2000. The authors found that PM 10 and O 3 were the two 

### 12 important pre dictors of mortality. Stylianou and Nicolich (2009 ) found that the estimated 

### 13
O 3 - mortality risks varied across the nine cities with the models exhibiting apparent 

### 14 thresholds, in the 10

- 45 ppb range for O 3 (3

- day accumulation). However, given the city



### 15

to

- city variation in risk estimates, combining the city

- specific estimates into an ove rall 

### 16 estimate complicates the interpretation of a threshold. Unlike the Xia and Tong (2006 ) 

### 17 analysis, Stylianou and Nicolich (2009 ) included a smooth function of time to adjust for 

### 18 seasonal/temporal confounding, which could explain the difference in results between the 

### 19
two studies. 

### 20

In conclusion, the evaluation of the O 3 - mortality C

- R relationship did not find any 

### 21 evidence that supports a threshold in the relationship between short

- term exposure to O 3 

### 22 and mortality within the range of O 3 concentrations observed in the U.S. Additionally, 

### 23 recent evidence suggests t hat the shape of the O 3 - mortality C

- R curve remains linear 

### 24 across the full range of O 3 concentrations. However, the studies evaluated demonstrated 

### 25 that the heterogeneity in the O 3 - mortality relationship across cities (or regions) 

### 26 complicates the interpreta tion of a combined C

- R curve and threshold analysis. Given the 

### 27 effect modifiers identified in the mortality analyses that are also expected to vary 

### 28 regionally (e.g., temperature, air conditioning prevalence), a national or combined 

### 29 analysis may not be appr opriate to identify whether a threshold exists in the O 3 - mortality 

### 30
C

- R relationship. Overall, the studies evaluated support a linear O 3 - mortality C

- R 

### 31 relationship and continue to support the conclusions from the 2006 O 3 AQCD, which 

### 32 stated that “if a popula tion threshold level exists in O 3 health effects, it is likely near the 

### 33
lower limit of ambient O 3 concentrations in the United States” ( U.S. EPA, 2006b )

. 

### 34

### Draft

– Do Not Cite or Quote 6

- 267 June 2012 6.6.2.5 Associations of Cause

- Specific Mortality and Short

- term Ozone Exposure

In the 2006 O 3 AQCD, an evaluation of studies that examined cause

- specific mortality 

### 1
found co nsistent positive associations between short

- term O 3 exposure and 

### 2 cardiovascular mortality, with less consistent evidence for associations with respiratory 

### 3 mortality. The majority of the evidence for associations between O 3 exposure and cause



### 4 specific mort ality were from single

- city studies, which had small daily mortality counts 

### 5 and subsequently limited statistical power to detect associations. 

### 6

New multicity studies evaluated in this review build upon and confirm the associations 

### 7
between short

- term O 3 exp osure and cause

- specific mortality identified in the 2006 O 3 

### 8 AQCD ( U.S. EPA, 2006b ) ( Figure 6

- 36 ; Table 6

- 53 ). In APHENA, a multicontinent 

### 9 study that consisted of the NMMAPS, APHEA2 and Canadian multicity datasets, 

### 10 consistent positive associations were reported for both cardiovascular and respiratory 

### 11 mortality in all

- year analyses when focusing on the natural spline model with 8 df/year 

### 12 ( Figure 6

- 36 ; Table 6

- 53 ). The associations between O 3 exposure and cardiovascular and 

### 13 respi ratory mortality in all

- year analyses were further supported by the multicity PAPA 

### 14 study ( Wong et al., 2010 ) . The magnitude of cardiovascular mortality associations were 

### 15 primarily larger in analyses restricted to the summer season compared to those observed 

### 16
in all

- year analyses ( Figure 6

- 36 ; Table 6

- 53 ). Additional multicity studies from the U.S. 

### 17 ( Zanobetti and Schwartz, 2008b ) and Europe ( Stafoggia et al., 2010 ; Samoli et al., 2009 ) 

### 18 that conducted summer season analyses provide evidence supporting associations 

### 19
between O 3 exposure and cardiovascular and respiratory mortality that are similar or 

### 20 larger in magnitude compared to those observed in all

- year analyses. 

### 21

Of the studies evaluated, only the APHENA study ( Katsouyanni et al., 2009 ) and an 

### 22 Italian multicity study ( Stafoggia et al., 2010 ) conducted an analysis of the potential for 

### 23 copollutant confounding of the O 3 cause

- specific mortality relationship. When focusing 

### 24 on the natural spline model with 8 df/year and lag 1 results (as discussed in 

### 25
Section 6.6.2.1 ), the APHENA study found that O 3 cause

- specific mortality risk estimates 

### 26 were fairly robust to the inclusion of PM 10 in copollutant models in the European dataset 

### 27 with more variability in the U.S. and Canadian datasets (i.e., copollutant risk estimates 

### 28 increased and decreased for respiratory and cardiovascular mortality). In summer season 

### 29 analyses cardiovascular O 3 mortality risk estimates we re robust in the European dataset 

### 30 and attenuated but remained positive in the U.S. datasets; whereas, respiratory O 3 

### 31 mortality risk estimates were attenuated in the European dataset and robust in the U.S. 

### 32 dataset. The authors did not examine copollutant mo dels during the summer season in the 

### 33 Canadian dataset ( Figure 6

- 29 ; Table 6

- 45 ). Interpretation of these results requires 

### 34 caution; however, due to the different PM sampling schedules employed in each of these 

### 35

### Draft

– Do Not Cite or Quote 6

- 268 June 2012 study locations (i.e., primarily every

- 6th day in the U.S. and Canadian datasets and 

### 1

every

- day in the European dataset). The results of the summer season analyses from the 

### 2 APHENA study ( Katsouyanni et al., 2009 ) are consistent with those from a study of 10 

### 3 Italian cities during the summer months ( Stafoggia et al., 2010 )

. Stafoggia et al. (2010 ) 

### 4
found that cardiovascular (14.3% [95% CI: 6.7, 22.4%]) and cerebrovascular (8.5% 

### 5 [95% CI: 0.06, 16.3%]) mortality O 3 effect estimates were robust to the inclusion of PM 10 

### 6 in copollutant models (14.3% [95% CI: 6.7, 23.1%] and 7.3% [95% CI:

- 1.2, 16.3], 

### 7 respectively), while respirat ory mortality O 3 effects estimates (17.6% [95% CI: 1.8, 

### 8 35.5%]) were attenuated, but remained positive (9.2% [95% CI:

- 6.9, 28.8%]). 

### 9

Effect estimates are for a 20 ppb increase in 24

- h avg; 30 in 8

- h max; and 40ppb increase in 1

- h max O 3 concentrations. Red = cardiovascular; blue = respiratory; closed circles = all

- year analysis; and open circles = summer
- only analysis. An “a” represents studies from the 2006 O 3 AQCD. A “b” represents risk estimates from APHENA

- Canada standardized to an a pproximate IQR of 5.1 ppb for a 1

- h max increase in O 3 concentrations (Section 6.2.7.2 ).


### Figure 6

- 36 Percent increase in cause

- specific mortality.

Study
Bell et al. (2005)a Wong et al. (2010) Katsouyanni et al. (2009)

Gryparis et al. (2004)a Samoli et al. (2009) Zanobetti and Schwartz (2008) Stafoggia et al. (2010) Katsouyanni et al. (2009)

Bell et al. (2005)a Wong et al. (2010) Katsouyanni et al. (2009)

Gryparis et al. (2004)a Zanobetti and Schwartz (2008) Katsouyanni et al. (2009)

Samoli et al. (2009) Stafoggia et al. (2010) Katsouyanni et al. (2009) Location

U.S. and non

- U.S. PAPA (4 cities) APHENA

- U.S. APHENA

- Canada APHENA

- Canada APHENA

- Europe APHENA

- U.S. APHENA

- Canada APHENA

- Canada APHENA

- Europe
21 European cities 21 European cities

48 U.S. cities 10 Italian cities APHENA

- U.S. APHENA

- Canada APHENA

- Canada APHENA

- Europe APHENA

- U.S. APHENA

- Canada APHENA

- Canada APHENA

- Europe

U.S. and non

- U.S. PAPA (4 cities) APHENA

- U.S. APHENA

- Canada APHENA

- Canada APHENA

- Europe APHENA

- U.S. APHENA

- Canada APHENA

- Canada APHENA

- Europe
21 European cities

48 U.S. cities APHENA

- U.S. APHENA

- Canada APHENA

- Canada APHENA

- Europe 21 European cities 10 Italian cities APHENA

- U.S. APHENA

- Canada APHENA

- Canada APHENA

- Europe Ages

All

≥75

<75

All

≥35 ≥75

<75

All

≥75

All

≥35 ≥75 Cardiovascular

Respiratory All

- Year

Summer

All

- Year

Summer Lag

NR 0

- 1 DL(0

- 2) DL(0

- 2) DL(0

- 2)b DL(0

- 2) DL(0

- 2) DL(0

- 2) DL(0

- 2)b DL(0

- 2)

0

- 1 0

- 1 0

- 3 DL(0

- 5) DL(0

- 2) DL(0

- 2) DL(0

- 2)b DL(0

- 2) DL(0

- 2) DL(0

- 2) DL(0

- 2)b DL(0

- 2)

NR 0

- 1 DL(0

- 2) DL(0

- 2) DL(0

- 2)b DL(0

- 2) DL(0

- 2) DL(0

- 2) DL(0

- 2)b DL(0

- 2)

0

- 1 0

- 3 DL(0

- 2) DL(0

- 2) DL(0

- 2)b DL(0

- 2)

0

- 1 DL(0

- 5) DL(0

- 2) DL(0

- 2) DL(0

- 2)b DL(0

- 2) ►

►

► ◄

◄

- 10

- 5 0 5 10 15 20 25 30
% Increase

### Draft

– Do Not Cite or Quote 6

- 269 June 2012 Table 6

- 53 Corresponding effect estimates for Figure 6

- 36.

Study * Location Ages Lag Avg Time %Increase (95% CI)

Cardiovascular

All

- year - Cardiovascular
Bell et al. (2005 ) a U.S. and non

- U.S. All NR 24

- h avg 2.23 (1.36,3.08) Wong et al. (2010 ) PAPA (4 cities) 0

- 1 8

- h max 2.20 (0.06, 4.37) Katsouyanni et al. (2009 ) APHENA

- U.S. ≥ 75 DL(0

- 2) 1

- h max 2.30 (

- 1.33, 6.04)

APHENA

- Canada DL(0

- 2) 8.96 (0.75,18.6)

APHENA

- Canada DL(0

- 2) b 1.1 (0.10,2.20)

APHENA

- europe DL(0

- 2) 2.06 (

- 0.24, 4.31)

APHENA

- U.S. <75 DL(0

- 2) 3.83 (

- 0.16, 7.95)

APHENA

- Canada DL(0

- 2) 7.03 (

- 2.71, 17.7)

APHENA

- Canada DL(0

- 2) b 0.87 (

- 0.35, 2.10)

APHENA

- europe DL(0

- 2) 1.98 (

- 1.09, 5.13)
Summer

– Cardiovascular
Gryparis et al. (2004 ) a 21 European cities All 0

- 1 8

- h max 2.7 (1.29,4.32) Samoli et al. (2009 ) 21 European cities 0

- 1 8

- h max 1.48 (0.18, 2.80) Zanobetti and Schwartz (2008b ) 48 U.S. cities 0

- 3 8

- h max 2.42 (1.45, 3.43) Stafoggia et al. (2010 ) 10 Italian cities ≥ 35 DL(0

- 5) 8

- h max 14.3 (6.65, 22.4) Katsouyanni et al. (2009 ) APHENA

- U.S. ≥ 75 DL(0

- 2) 1

- h max 3.18 (

- 0.47, 6.95)

APHENA

- Canada DL(0

- 2) 1.50 (

- 2.79, 5.95)

APHENA

- Canada DL(0

- 2) b 0.19 (

- 0.36, 0.74)

APHENA

- europe DL(0

- 2) 3.67 (0.95, 6.53)

APHENA

- U.S. <75 DL(0

- 2) 6.78 (2.70, 11.0)

APHENA

- Canada DL(0

- 2)

- 1.02 (

- 4.23, 2.30)

APHENA

- Canada DL(0

- 2) b

- 0.13 (

- 0.55, 0.29)

APHENA

- europe DL(0

- 2) 2.22 (

- 1.48, 6.04) Respiratory

All

- years - Respiratory
Bell et al. (200 5 ) a U.S. and non

- U.S. All NR 24

- h avg 0.94 (

- 1.02, 2.96) Wong et al. (2010 ) PAPA (4 cities) 0

- 1 8

- h max 2.02 (

- 0.41, 4.49) Katsouyanni et al. (2009 ) APHENA

- U.S. DL(0

- 2) 1

- h max 2.54 (

- 3.32, 8.79)

APHENA

- Canada DL(0

- 2) 1.02 (

- 11.9, 15.9)

APHENA

- Canada DL(0

- 2) b 0.13 (

- 1.60, 1.90)

APHENA

- europe DL(0

- 2) 1.82 (

- 2.18, 6.04)

APHENA

- U.S. ≥ 75 DL(0

- 2) 1.10 (

- 6.48, 9.21)

APHENA

- Canada DL(0

- 2)

- 4.61 (

- 19.3, 13.3)

APHENA

- Canada DL(0

- 2) b

- 0.60 (

- 2.70, 1.60)

APHENA

- europe DL(0

- 2) 1.10 (

- 3.48, 5.95)

### Draft

– Do Not Cite or Quote 6

- 270 June 2012 Study * Location Ages Lag Avg Time %Increase (95% CI)

Summer

- Respiratory
Gryparis et al. (2004 ) a 21 European cities All 0

- 1 8

- h max 6.75 (4.38, 9.10) Zanobetti and Schwartz (2008b ) 48 U.S. cities 0

- 3 8

- h max 2.51 (1.14, 3.89) Katsouyanni et al. (2009 ) APHENA

- U.S. DL(0

- 2) 1

- h max 4.40 (

- 2.10, 11.3)

APHENA

- Canada DL(0

- 2) 26.1 (13.3, 41.2)

APHENA

- Canada DL(0

- 2) b 3.00 (1.60, 4.50)

APHENA

- europe DL(0

- 2) 3.83 (

- 1.33, 9.21) Samoli et al. (2009 ) 21 European cities 0

- 1 8

- h max 2.38 (0.65, 4.19) Stafoggia et al. (2010 ) 10 Italian cities ≥ 35 DL(0

- 5) 8

- h max 17.6 (1.78, 35.5) Katsouyanni et al. (2009 ) APHENA

- U.S. ≥ 75 DL(0

- 2) 1

- h max 4.07 (

- 4.23, 13.0)

APHENA

- Canada DL(0

- 2) 19.5 (2.22, 40.2)

APHENA

- Canada DL(0

- 2) b 2.30 (0.28, 4.40)

APHENA

- europe DL(0

- 2) 2.46 (

- 3.40, 8.62)

*Studies from Figure 6

- 36 , plus others.

a Studies from the 2006 O 3 AQCD.

b Risk estimates from APHENA

- Canada standardized to an approximate IQR of 5.1 ppb for a 1

- h max increase in O 3 concentrations (Section 6.2.7.2 ).
Collectively, the results from the new multicity studies provide evidence of associations 

### 1
between short

- term O 3 exposure and cardiovascular and respiratory mortality with 

### 2 additional evidence indicating these associations persist, and in some cases the magnitude 

### 3 of associations are increased, in the summer season. Although copollut ant analyses of 

### 4

cause

- specific mortality are limited, the APHENA study found that O 3 cause

- specific 

### 5 mortality risk estimates were fairly robust to the inclusion of PM 10 in copollutant models 

### 6 when focusing on the dataset with daily PM 10 data (i.e., the Euro pean dataset), which is 

### 7 supported by the results from Stafoggia et al. (2010 ) . Additionally, APHENA found that 

### 8
O 3 cause

- specific mortality risk estimates were moderately to substantially sensitive 

### 9 (e.g., increased or attenuated) to inclusion of PM 10 in the U.S. and Canadian datasets. 

### 10 However, the mostly every

- 6th

- day sampling schedule for PM 10 in the U.S. and Canadia n 

### 11 datasets greatly reduced their sample size and limits the interpretation of these results. 

### 12

6.6.3 Summary and Causal Determination

The evaluation of new multicity studies that examined the association between short

- term 

### 13
O 3 exposure and mortality found evidence which supports the conclusions of the 2006 O 3 

### 14 AQCD. These new studies reported consistent positive associations between short

- term 

### 15
O 3 exposure and all

- cause (nonaccidental) mortality, with associations persisting or 

### 16 increasing in magnitude during the warm season, and provide additional support for 

### 17
associations between O 3 exposure and cardiovascular and respiratory mortality. 

### 18

### Draft

– Do Not Cite or Quote 6

- 271 June 2012 Recent studies further examined potential confounders (e.g., copollutants and seasonality) 

### 1
of the O 3 - mortality relationship. Because the PM

- O 3 correlation varies across regions, 

### 2 due to the difference in PM chemical constituents, interpretation of the combined effect 

### 3 of PM on the relationship between O 3 and mortality is not straightforward. Unlike 

### 4 previous studies that were limited to p rimarily examining the confounding effects of 

### 5
PM 10 , the new studies expanded their analyses to include multiple PM indices (e.g., PM 10 , 

### 6
PM 2.5 , and PM components). An examination of copollutant models found evidence that 

### 7
associations between O 3 and all

- caus e mortality were robust to the inclusion of PM 10 or 

### 8
PM 2.5 ( Stafoggia et al., 2010 ; Katsouyanni et al., 2009 ; Bell et al., 2007 ) , while other 

### 9 studies found evidence for a modest reduction (~20

- 30%) when examining PM 10 ( Smith 

### 10 et al., 2009b ) . Additional evidence suggests potential sensitivity (e.g., increases and 

### 11 attenuation) of O 3 mortality risk estim ates to copollutants by age group or cause

- specific 

### 12 mortality (e.g., respiratory and cardiovascular) ( Stafoggia et al., 2010 ; Katsouyanni et al., 

### 13
2009 ) . An examination of PM components, specifically sulfate, found evidence for 

### 14
reductions in O 3 - mortality risk estimates in copollutant models ( Franklin and Schwartz, 

### 15
2008 ) . Overall, across studies, the potential impact of PM indices on O 3 - mortality risk 

### 16
estimates tended to be much smaller than the variation in O 3 - mortality risk estimates 

### 17 across cities suggesting that O 3 effects are independent of the relationship between PM 

### 18 and mortality. However, interpretation of the potential confounding effects of PM on 

### 19
O 3 - mortality risk estimates requires caution. This i s because the PM

- O 3 correlation varies 

### 20 across regions, due to the difference in PM components, complicating the interpretation 

### 21 of the combined effect of PM on the relationship between O 3 and mortality. Additionally, 

### 22 the limited PM or PM component datasets used as a result of the every

- 3rd

- and 6th

- day 

### 23 PM sampling schedule instituted in most cities limits the overall sample size employed to 

### 24 examine whether PM or one of its components confounds the O 3 - mortality relationship. 

### 25

An examination of potential seasonal confounding of the O 3 - mortality relationship found 

### 26 that the extent of smoothing or the methods used for adjustment can influence O 3 risk 

### 27 estimates when not applying enough degrees of freedom to control for temporal/season 

### 28
trends ( Katsouyanni et al., 2009 ) . This is because of the opposing seasonal trends 

### 29
between O 3 and mortality. 

### 30

The multicity studies evaluated within this section also examined the regional 

### 31 heterogeneity observed in O 3 - mortality risk estimates. These studies provide evidence 

### 32 which suggests generally higher O 3 - mortality risk estimates in northeastern U.S. cities 

### 33 with some regions showing no associations between O 3 exposure and mortali ty 

### 34 (e.g., Southwest, Urban Midwest) ( Smith et al., 2009b ; Bell and Dominici, 2008 )

. 

### 35 Multicity studies that examined individual

- and community

- level characteristics 

### 36 identified characteristics that may explain the observe d regional heterogeneity in 

### 37
O 3 - mortality risk estimates as well as characteristics of populations potentially at greatest 

### 38

### Draft

– Do Not Cite or Quote 6

- 272 June 2012 risk for O 3 - related health effects. An examination of community

- level characteristics 

### 1
found an increase in the O 3 - mortality risk estim ates in cities with higher unemployment, 

### 2 percentage of the population Black/African

- American, percentage of the working 

### 3 population that uses public transportation, lower temperatures, and lower prevalence of 

### 4 central air conditioning ( Medina

- Ramón and Schwartz, 2008 ) . Additionally, a potential 

### 5 interactive, or synergistic, effect on the O 3 - mortality relationship was observed when 

### 6

ex amining differences in the O 3 - mortality association across temperature levels ( Ren et 

### 7 al., 2008 ) . An examination of individual

- level characteristics found evidence that older 

### 8 age, female sex, Blac k race, having atrial fibrillation, SES indicators (i.e., educational 

### 9 attainment, income level, and employment status), and out

- of hospital deaths, specifically 

### 10 in those individuals with diabetes, modify O 3 - mortality associations ( Cakmak et al., 

### 11
2011 ; Stafoggia et al., 2010 ; Medina

- Ramón and Schwartz, 2008 ) , and lead to increased 

### 12
risk of O 3 - related mortality. Overall, additional research is warranted to further confir m 

### 13 whether these characteristics, individually or in combination, can explain the observed 

### 14 regional heterogeneity. 

### 15

Additional studies were evaluated that examined factors that may influence the shape of 

### 16
the O 3 - mortality C

- R curve, such as multi

- day effect s, mortality displacement, adaptation, 

### 17 the use of different exposure metrics (i.e., 24

- h avg, 8

- h max or 1

- h max), and whether a 

### 18
threshold exists in the O 3 - mortality relationship. An examination of multiday effects in a 

### 19 U.S. and European multicity study fo und conflicting evidence for mortality displacement, 

### 20 but both studies suggest that the positive associations between O 3 and mortality are 

### 21 observed mainly in the first few days after exposure ( Samoli et al., 2009 ; Zanobetti and 

### 22 Schwartz, 2008b ) . A U.S. multicity study found evidence of an adaptive response to O 3 

### 23 exposure, with the highest risk estimates earlier in the O 3 season (i.e., July) and 

### 24 diminished effects later (i.e., August) ( Zanobetti and Schwartz, 2008a ) . However, the 

### 25 evidence of adaptive effects has an implication for the interpretation of multi

- day effects, 

### 26 and requires further analysis. The limited number of studies conducted that examined the 

### 27
effect of using different exposure metrics (i.e., 1

- h max, 8

- h max, and 24

- h avg) when 

### 28 examining the O 3 - mortality relationship found relatively comparable O 3 - mortality risk 

### 29 estimates across the exposure metrics used ( Smith et al., 2009b ; Gryparis et al., 2004 )

. 

### 30 Analyses that specifically focused on the O 3 - mortality C

- R relationship supported a linear 

### 31
O 3 - mortality relationship and found no evidence of a threshold within the range of O 3 

### 32

conce ntrations in the U.S., but did observe evidence for potential differences in the C

- R 

### 33 relationship across cities ( Katsouyanni et al., 2009 ; Stylianou and Nicolich, 2009 ; Bell et 

### 34 al., 2006 ) . Collectively, these studies support the conclusions of the 2006 O 3 AQCD that 

### 35 “if a population threshold level exists in O 3 health effects, it is likely near the lower limit 

### 36
of ambient O 3 concentrations in the U.S.” 

### 37

### Draft

– Do Not Cite or Quote 6

- 273 June 2012 Studies that examined the association between short

- term O 3 exposure and cause

- specific 

### 1 mortality confirm the associations with both cardiovascular and respiratory mortality 

### 2 reported in the 2006 O 3 AQCD ( Stafoggia et al., 2010 ; Wong et al., 2010 ; Katsouyanni et 

### 3 al., 2009 ; Samoli et al., 2009 ; Zanobetti and Schwartz, 2008b ) . These associations were 

### 4 primarily larger in magnitude during the summer s eason compared to all

- year analyses. 

### 5 Of the studies that examined the potential confounding effects of PM [i.e., Stafoggia et al. 

### 6 (2010 ); Katsouyanni et al. (2009 ) ], O 3 mortality associations remained relatively robust 

### 7 in copollutant models, but interpretation of these studies was complicated by the different 

### 8 PM sampling sched ules (e.g., every

- 6th

- day) employed in each study. Overall, the strong 

### 9 evidence for respiratory effects due to short

- term O 3 exposure (Section 6.2 ) are consistent 

### 10 across disciplines and provides coherence for the respiratory mortality associations 

### 11 observed across studies. However, the strong evidence for O 3 - induced cardiovascular 

### 12
mortal ity is complicated by toxicological studies that provide initial evidence for a 

### 13 biologically plausible mechanism for O 3 - induced cardiovascular mortality, but a lack of 

### 14 coherence with controlled human exposure and epidemiologic studies of cardiovascular 

### 15

mor bidity that do not demonstrate consistent evidence of O 3 - induced cardiovascular 

### 16 effects (Section 6.3 ). 

### 17

In conclusion, the recent epidemiologic studi es build upon and confirm the associations 

### 18
between short

- term O 3 exposure and all

- cause and cause

- specific mortality reported in the 

### 19
2006 O 3 AQCD. However, there is a lack of coherence across disciplines and consistency 

### 20
across health outcomes for O 3 - induce d cardiovascular morbidity (Section 6.3 ) which do 

### 21 not support the relatively strong epidemiologic evidence for O 3 - related cardiovascular 

### 22 mortality. Overall, recent studies have provided additional information regarding key 

### 23 uncertainties (previously identified

- including the potential confounding effects of 

### 24 copollutants and seasonal trend), individual

- and community

- level factors that may lead 

### 25
to inc reased risk of O 3 - induced mortality and the heterogeneity in O 3 - mortality risk 

### 26 estimates, and continued evidence of a linear no

- threshold C

- R relationship. Although 

### 27 some uncertainties still remain, the collective body of evidence is sufficient to conclude 

### 28
that ther e is likely to be a causal relationship between short

- term O 3 exposure and 

### 29
total mortality

. 

### 30



## 6.7 Overall Summary

The evidence reviewed in this chapter describes the recent findings regarding the health 

### 31
effects of short

- term exposure to ambient O 3 conce ntrations. Table 6

- 54 provides an 

### 32 overview of the causal determinations for each of the health categories evaluated. 

### 33

### Draft

– Do Not Cite or Quote 6

- 274 June 2012 Table 6

- 54 Summary of causal determinations for short

- term exposures to
ozone.
Health Category Causal Determination Respiratory Effects Causal relationship
Cardiovascular Effects Suggestive of a causal relationship
Central Nervous System Effects Suggestive of a causal relationship
Effects on Liver and Xenobiotic Metabolism Inadequate to infer a causal relationship
Effects on Cutaneous and Ocular Tissues Inadequate to infer a causal relationship
Total Mortality Likely to be a caus al relationship

### Draft

– Do Not Cite or Quote 6

- 275 June 2012 

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