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## 6 INTEGRATED HEALTH EF FECTS OF SHORT TERM OZONE EXPOSURE

6.1 Introduction This chapter reviews, summarizes, 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 relationships of short

- term O 3 exposure with a range of 

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

### 5 and mortality (S ections 6.2, 6.3, and 6.6). A smaller number of studies are available to 

### 6 assess the effects of O 3 on other physiological systems such as the central nervous system 

### 7 (Section 6.4), liver and metabolism (Section 6.5.1), and cutaneous and ocular tissues 

### 8 (Secti on 6.5.2). 

### 9 Evidence for the major health effect categories (e.g., respiratory, cardiovascular, 

### 10 mortality) is described in individual sections that include a brief summary of conclusions 

### 11 from the 2006 O 3 AQCD and an evaluation of recent evidence that is in tended to build 

### 12 upon evidence from previous reviews. Within each section, results are organized by 

### 13 health endpoint (e.g., lung function, pulmonary inflammation) then by specific scientific 

### 14 discipline (e.g., controlled human exposure, epidemiology, and toxi cology). Each major 

### 15 section (e.g., respiratory, cardiovascular, mortality) concludes with an integrated 

### 16 summary of the findings and a conclusion regarding causality. Based upon the framework 

### 17 described in the Preamble to this ISA, a determination of causali ty is made for a broad 

### 18 health effect category, such as respiratory effects, with coherence and plausibility being 

### 19 based on the evidence available across disciplines and also across the suite of related 

### 20 health endpoints, including cause

- specific mortality. 

### 21



## 6.2 Respiratory Effects Based on evidence integrated across human controlled exposure, epidemiologic, and 

### 22 toxicological studies, the 2006 O 3 AQCD concluded that there was clear, consistent 

### 23 evidence of a causal relationship between short

- term O 3 exposure and r espiratory effects 

### 24 ( U.S. EPA, 2006b ) . Contributing to this conclusion were consistent and coherent 

### 25 observations across scientific disciplines of associations of short

- term O 3 exposures with 

### 26 pulmonary function decrements and increases in lung inflammation, lung permeability, 

### 27 and airway hyperresponsiveness. Collectively, these findings provided biological 

### 28Draft

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- 2 September 2011 plausibility for associations in epidemiologic studies of short

- term ambient O 3 exposure 

### 1 with respiratory symptoms and respiratory

- relate d hospitalizations and emergency 

### 2 department (ED) visits. 

### 3 Controlled human exposure studies have provided strong and quantifiable exposure



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

### 5 studies reviewed in the 1996 and 2 006 O 3 AQCDs were that: (1) young healthy adults 

### 6 exposed to O 3 concentrations ≥ 80 ppb develop significant reversible, transient 

### 7 decrements in pulmonary function if minute ventilation (V E ) or duration of exposure is 

### 8 increased sufficiently; (2) relative to young adults, children experience similar 

### 9 spirometric responses but lesser symptoms from O 3 exposure; (3) relative to young 

### 10 adults, O 3 - induced spirometric responses are decreased in older individuals; (4) there is a 

### 11 large degree of intersubject variability in physiologic and symptomatic responses to O 3, 

### 12 but responses tend to be reproducible within a given individual over a period of 

### 13 several months; (5) subjects exposed repeatedly to O 3 for several days experience an 

### 14 attenuation of spirometric and symptomati c responses on successive exposures, that is 

### 15 lost after about a week without exposure; and (6) acute O 3 exposure initiates an 

### 16 inflammatory response that may persist for at least 18 to 24 hours postexposure. 

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

### 18 derived from the coherence between toxicological and controlled human exposure studies 

### 19 examining parallel endpoints. For example, O 3 - induced decrements in lung function have 

### 20 also been observed in animals, and as in humans, tolerance or attenuation has been 

### 21 demonstrated in animal models. Both humans and rodents exhibit increased airway 

### 22 hyperresponsiveness. This is an important consequence of exposure to ambient O 3 , 

### 23 because the airways are then predisposed to narrowing upon inhalation of a variety of 

### 24 ambient stimuli. Additionally, airway hyperresponsiveness tends to resolve more slowly 

### 25 and appears less subject to attenuation. Increased permeability and inflammation have 

### 26 been observed in the airways of humans and animals alike after O 3 exposure, although 

### 27 these processes are not necessarily associated with immediate changes in lung function or 

### 28 hyperresponsiveness. Furthermore, the potential relationship between repetitive bouts of 

### 29 acute inflammation and the development of chronic respiratory disease is unknown. 

### 30 Another feature of O 3 exposure - related respiratory morbidity is impaired host defense 

### 31 and reduced resistance to lung infection, which has been strongly supported by 

### 32 toxicological evidence and to a limited extent by h uman data. Recurrent respiratory 

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

### 34 In epidemiologic studies, short

- term O 3 - related respiratory morbidity has been assessed 

### 35 most frequently using lung function. Several studie s of healthy children attending camps 

### 36 as well as studies of outdoor workers, groups exercising outdoors, and children with 

### 37Draft

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- 3 September 2011 asthma support O 3 effects on lung function decrements at ambient levels ( U.S. EPA, 

### 1 2006b , 1996a ) . In addit ion to lung function, ambient O 3 exposure has been associated 

### 2 with increases in respiratory symptoms (e.g., cough, wheeze, shortness of breath), 

### 3 especially in large U.S. panel studies of children with asthma ( Gent et al., 2003 ; 

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

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

### 6 demonstrated consistent positive associations between O 3 exposure and respiratory 

### 7 hospital admi ssions and ED visits, specifically during the summer or warm months. In 

### 8 contrast with other respiratory health endpoints, the association between short

- term O 3 

### 9 exposure and respiratory mortality is less clearly indicated. Although O 3 has been 

### 10 consistently associated with nonaccidental and cardiopulmonary mortality, the 

### 11 contribution of respiratory causes to these findings has been uncertain as the few studies 

### 12 that have examined mortality specifically from respiratory causes have reported 

### 13 inconsistent associa tions with ambient O 3 exposures. 

### 14 As discussed throughout this section, consistent with the strong body of evidence 

### 15 presented in the 2006 O 3 AQCD, recent studies continue to support associations between 

### 16 short

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

### 17 controlled human exposure studies, airway inflammatory responses in toxicological 

### 18 studies, and respiratory

- related hospitalizations and ED visits. Recent epidemiologic 

### 19 studies contribute new evidence on at

- risk populat ions and of associations of ambient O 3 

### 20 exposures with biological markers of airway inflammation and oxidative stress, which is 

### 21 consistent with the extensive evidence from human controlled exposure and toxicological 

### 22 studies. Furthermore, extending the poten tial range of well

- established O 3 - associated 

### 23 respiratory effects, new multicity studies and a multicontinent study demonstrate 

### 24 associations between short

- term ambient O 3 exposure and respiratory

- related mortality. 

### 25

6.2.1 Lung Function

6.2.1.1 Controlled Human Exposure
Th is section focuses on studies examining O 3 effects on lung function and respiratory 

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

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

### 28 Respons es to acute O 3 exposures in the range of ambient concentrations include 

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

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

### 31 Reflex inhibition of inspiration results in a decrease in forced vital capacity (FVC) and 

### 32Draft

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- 4 September 2011 total lung capacity (TLC) and, in combination with mild bronchoconstriction, contributes 

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

### 2 In studies that have expose d subjects during exercise, the majority of shorter duration 

### 3 (≤ 4

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

### 4 rotated between 15

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

- to 2

- h our 

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

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

### 7 where subjects complete 50

- minute periods of exercise followed by 10

- minute rest 

### 8 periods. 

### 9 The majori ty of controlled human exposure studies have been conducted within 

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

### 11 O 3 . Little effort has been made herein to differentiate between facemask and chamber 

### 12 exposures as FEV 1 a nd respiratory symptom responses appear minimally affected by 

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

### 14 have been reported for exposures to 80 and 120 ppb O 3 (6.6 h, moderate quasi continuous 

### 15 exercise, 40 L/min) an d 300 ppb O 3 (2 h, heavy intermittent exercise, 70 L/min) ( Adams, 

### 16 2 003a , b , 2002 )

. 

### 17 The majority of controlled human exposure studies investigating the effects O 3 are of a 

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

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

### 20 control) and, depending on the study, to one or more O 3 concentrations. The FA control 

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

### 22 the outco me(s) of interest. Comparison of responses following this FA exposure to those 

### 23 following an O 3 exposure allows for estimation of the effects of O 3 itself on an outcome 

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

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

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

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

### 28 c orrected or adjusted for such extraneous responses as measured during FA exposures. 

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

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

### 31 exposu res to FA, group mean FEV 1 changes have ranged from

- 0.7% ( McDonnell et al., 

### 32 1991 ) to 2.7% ( Adams, 2006a ) . On average, across ten 6.6

- hour exposure studies, there 

### 33 has been a 1.0% (n=279) increase in FEV 1 ( Kim et al., 2011 ; Schelegle et al., 2009 ; 

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

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

### 36 reason for small changes in FEV 1 over the course of FA exposures, whether biologically 

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- 5 September 2011 based or a systemati c effect of the experimental procedures, the use of FA responses as a 

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

### 2 studies serves to eliminate alternative explanations other than those of O 3 itself in causing 

### 3 the mea sured responses. 

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

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

### 6 improvement observed with FA exposure. Noting that some healthy individua ls 

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

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

### 9 having their own control exposure to FA to discern relatively small effects with c ertainty 

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

### 11 experimental design. The utility of FA control exposures becomes more apparent when 

### 12 considering individuals with respiratory disease. The occurrence of exerci se - induced 

### 13 bronchospasm is well recognized to in patients with asthma and COPD and may be 

### 14 experienced during both FA and O 3 exposures. Absent correction for FA responses, 

### 15 exercise

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

### 16 biol ogical phenomenon serves as an example to emphasize the need for a proper control 

### 17 exposure in assessing the effects of O 3 as well as the role of this control in eliminating the 

### 18 influence of other factors on the outcomes of interest. 

### 19
Pulmonary Function Eff ects of Ozone Exposure in Healthy Subjects Acute Exposure of Healthy Subjects The majority of controlled human exposure studies have investigated the effects of 

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

- 35 years of age). These studies 

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

### 22 conditions and subject activity levels. The magnitude of respiratory effects (decrements 

### 23 in spirometry and symptomatic response) in these individuals is a function of O 3 

### 24 concentration (C), minute ventilation (V E ), and exposure duration (time). Any physical 

### 25 activity will increase minute ventilation and therefore the dose of inhaled O 3 . Dose of 

### 26 inhaled O 3 to the lower airways is also increased due to a shift from nasal to oronasal 

### 27 breathi ng with a consequential decrease in O 3 scrubbing by the upper airways. Thus, the 

### 28 intensity of physiological response following an acute exposure will be strongly 

### 29 associated with minute ventilation. 

### 30 The product of C × V E × time, although actually a measure of exposure, is commonly 

### 31 used as a surrogate for O 3 dose to the respiratory tract in controlled human exposure 

### 32 studies. The delivery of O 3 to the lower respiratory tract varies as a function of breathing 

### 33 conditions (route and pattern). And, the dose of O 3 to the lower respiratory tract can vary 

### 34Draft

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- 6 September 2011 between similarly exposed individuals. In support of the use of the product (C × V E × 

### 1 time) as a surrogate for O 3 dose, differences in FEV 1 responses among young healthy 

### 2 adults (32 M, 28 F) exposed to O 3 (250 ppb, 3 0 L/min, 2 h) do not appear to be explained 

### 3 by intersubject differences in the fraction of inhaled O 3 retained in the lung ( Ultman et 

### 4 al., 2004 ) . Using the product of C × V E × time as a surrogate for O 3 dose is also useful in 

### 5 distinguishing between the well defined and characterized exposure of subje cts in 

### 6 controlled human exposure studies as opposed to the use of ambient O 3 concentration to 

### 7 characterize exposure in epidemiologic studies. 

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

### 9 concentration reported to produce a statistically significant O 3 - induced group mean FEV 1 

### 10 decrement of 6.4% (n=10) ( Folinsbee et al., 1978 ) to 6.7% (n=13) ( Horvath et al., 1979 )

. 

### 11 Airway resistance was not clearly affected during at

- rest exposure to these 

### 12 O 3 concentrations. When exposed to 200 ppb for 2.25 h during intermittent periods of rest 

### 13 and brisk walking, young healthy subjects (83 M, 55 F) show a statistically significant 

### 14 group mean FEV 1 decrement of 8.8% following O 3 exposure ( Que et al. ) . For exposures 

### 15 of 1

- 2 hours to ≥ 120 ppb O 3 , statistically significant symptomatic responses and effects 

### 16 on FEV 1 are observed when V E is sufficiently increased by exercise ( McDonnell et al., 

### 17 1999 ) . For instance, 5% of young healthy adults exposed to 400 ppb for 2 h during rest 

### 18 experienced pain on deep inspiration. Respiratory symptoms were not observed at lower 

### 19 exposure concentrations (120

- 300 ppb) or with only 1 h of exposure. However, when 

### 20 exposed to 120 ppb for 2 h during moderate intermittent exercise, 9% of individuals 

### 21 experienced pai n on deep inspiration, 5% experienced cough, and 4% experienced 

### 22 shortness of breath. With very heavy continuous exercise (V E = 89 L/min), an O 3 - induced 

### 23 group mean decrement of 9.7% in FEV 1 has been reported for healthy young adults 

### 24 exposed for 1 hour to 12 0 ppb O 3 ( Gong et al., 1986 ) . Symptoms are present and 

### 25 decrements in forced e xpiratory volumes and flows occur at 160

- 240 ppb O 3 following 1 

### 26 hour of continuous heavy exercise (V E ≈ 55 to 90 L/min ( Gong et al., 1986 ; Avol et al., 

### 27 1984 ; Folinsbee et al., 1984 ; Adams and Schelegle, 1983 ) and following 2 hours of 

### 28 intermittent heavy exercise (V E ≈ 65

- 68 L/min) ( Linn et al., 1986 ; Kulle et al., 1985 ; 

### 29 McDonnell et al., 1983 ) . With heavy interm ittent exercise (15

- min intervals of rest and 

### 30 exercise [V E = 68 L/min]), symptoms of breathing discomfort and a group mean O 3 - 

### 31 induced decrement of 3.4% in FEV 1 occurred in young healthy adults exposed for 2 

### 32 hours to 120 ppb O 3 ( McDonnell et al., 1983 )

. 1 

### 33

1 In total, subjects were exposed to O 3 for 2.5 hours. Intermittent exercise periods, however, were only 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 September 2011 

### A
Source: Brown et al. ( 2008 )



### B Studies appearing in the figure legends are: Adams ( 2006a , 2003a , 2002 , 1998 ) , Folinsbee et al. ( 1988 ) , Horstman et al. ( 1990 ) , Kim et al. ( 2011 ) , McDonnell et al. ( 2007 ; 1991 ) , and Schelegle et al. ( 2009 )

.

Top, pan el A: all studies exposed subjects to a constant (square
- wave) concentration in a chamber, except Adams ( 1998 ) where a facemask was used. The McDonnell et al. ( 2007 ) curve illustrates the predicted FEV 1 decrement at 6.6 hours as a function of o zone 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: a ll studies used constant (square
- wave) exposures in a chamber unless designated as triangular (t) and/or facemask (m) exposures. 

### Figure 6 - 1 Cross - study comparison of mean ozone - induced FEV 1 

### decrements following 6.6 hours of exposure to ozone
. During eac h 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 pp m have been offset for illustrative purposes. 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) Adams (1998) 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) 8

6

4

2

0Ozone-InducedFEV1decrement (%)

0.03Draft

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- 8 September 2011 For prolonged (6.6 hours) exposures relative to shorter exposures, significant 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 results from studies using 6.6 hours of 

### 3 constant or square

- wave (S

- W) exposures to between 40 and 120 ppb are illustrated in 

### 4 Figure 6

- 1 (A)

. Figure 6

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

### 5 triangular exposure protocols as w ell as facemask exposures. Exposure to 40 ppb for 6.6 

### 6 hours produces small, statistically insignificant changes in FEV 1 that are relatively 

### 7 similar to responses from FA exposure ( Adams, 2002 ) . Volunteers exposed to 60 ppb O 3 

### 8 experience group mean O 3 - induced FEV 1 decrements of about 3% ( Kim et al., 2011 ; 

### 9 Brown et al., 2008 ) ( Adams, 2006a ) 1 ; those exposed to 80 ppb have group mean 

### 10 decrements which range from 6 to 8% ( Adams, 2006a , 2003a ; McDonnell et al., 1991 ; 

### 11 Hors tman et al., 1990 ) ; at 100 ppb, group mean decrements range from 8 to 14% 

### 12 ( McDonnell et al., 1991 ; Horstman et al., 1990 ) ; and at 120 ppb, group mean decrements 

### 13 of 13 to 16% are observed ( Adams, 2002 ; Horstman et al., 1990 ; Folinsbee et al., 1988 )

. 

### 14 As illustrated in Figure 6

- 1, there is a smooth dose

- response curve without evidence of a 

### 15 threshold for exposure s between 40 and 120 ppb O 3 . Taken together, these data indicate 

### 16 that mean FEV 1 is clearly decreased by 6.6

- h exposures to 60 ppb O 3 and higher 

### 17 concentrations in subjects performing moderate exercise. 

### 18 As opposed to constant or S

- W concentration patterns u sed in the studies described 

### 19 above, many studies conducted at the levels of 40

- 80 ppb have used variable O 3 

### 20 concentration patterns. It has been suggested that a triangular (variable concentration) 

### 21 exposure profile can potentially lead to higher FEV 1 respon ses than S

- W profiles despite 

### 22 having at the same average O 3 concentration over the exposure period. Hazucha et al. 

### 23 ( 1992 ) were the first to investigate the effects of variable versus constant concentration 

### 24 exposures on responsiveness to O 3 . In their study, volunteers were randomly exposed to a 

### 25 triangular concentration profile (averaging 120 ppb over the 8

- h exposure) that in creased 

### 26 linearly from 0

- 240 ppb for the first 4 hours of the 8

- h exposure, then decreased linearly 

### 27 from 240 to 0 ppb over the next 4 hours of the 8

- h exposure, and to an S

- W exposure of 

### 28 120 ppb O 3 for 8 hours. While the total inhaled O 3 doses at 4 hours an d 8 hours for the S



### 29 W and the triangular concentration profile were almost identical, the FEV 1 response was 

### 30 dissimilar. For the S

- W exposure, FEV 1 declined ~5% by the fifth hour and then 

### 31 remained at that level. With the triangular O 3 profile, there was min imal FEV 1 response 

### 32 over the first 3 hours followed by a rapid decrease in FEV 1 (

- 10.3%) over the next 3 

### 33

1 Adams ( 2006a ) did not find effects on FEV 1 at 60 ppb to be statistically significant. In an analysis of the Adams ( 2006a ) 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

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- 9 September 2011 hours. During the seventh and eighth hours, mean FEV 1 decrements improved to

- 6.3% 

### 1 as the O 3 concentration decreased from 120 to 0 ppb (mean = 60 ppb). These findings 

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

### 3 time

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

### 4 recovery during the course of an exposure. 

### 5 Subsequently, others have also demonstrated that variable concentration exposures can 

### 6 elicit greater FEV 1 and symptomatic responses than do S

- W exposures ( A dams, 2006a , b , 

### 7 2003a ) . Adams ( 2006b ) reproduced the findings of Hazucha et al. ( 1992 ) at 120 p pb. 

### 8 However, Adams ( 2006a , 2003a ) found that responses from an 80 ppb O 3 (average) 

### 9 triangular exposure did not differ significantly from those observed in the 80 ppb O 3 S

- W 

### 10 exposure at 6.6 hours. Nevertheles s, FEV 1 and symptoms were significantly different 

### 11 from pre

- exposure at 4.6 hours (when the O 3 concentration was 150 ppb) in the triangular 

### 12 exposure, but not until 6.6 hours in the S

- W exposure. At the lower O 3 concentration of 

### 13 60 ppb, no temporal pattern d ifferences in FEV 1 responses between S

- W and triangular 

### 14 exposure profiles could be discerned ( Adams, 2006a ) . However, total symptom scores 

### 15 were significantly increased for the 60 ppb triangular (but n ot the S

- W) exposure 

### 16 following 5.6 and 6.6 hours of exposure. At 80 ppb, respiratory symptoms tended to 

### 17 increase more rapidly during the triangular than S

- W exposure protocol, but then 

### 18 decreased during the last hour of exposure to be less for the triangula r than the S

- W 

### 19 exposure at 6.6 h. Both total symptom scores and pain on deep inspiration were 

### 20 significantly increased following exposures to 80 ppb relative to all other exposure 

### 21 protocols, i.e., FA, 40, and 60 ppb exposures. Following the 6.6

- hour exposur e s, 

### 22 respiratory symptoms at 80 ppb were rougly 2

- 3 times greater than observed at 60 ppb. 

### 23 At 40 ppb, triangular and S

- W patterns produced spirometric and subjective symptom 

### 24 responses similar to FA exposure ( Adams, 2006a , 2002 )

. 

### 25 For exposures of 60 ppb and greater, these studies ( Adams, 2006a , b , 2003a ; H azucha et 

### 26 al., 1992 ) demonstrate that during triangular exposure protocols, volunteers exposed 

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

### 28 symptomatic responses during and following peak O 3 concentrations as compared to 

### 29 responses over the same time interval of S

- W exposures. This observation is not 

### 30 unexpected since the inhaled dose rate during peaks of t he triangular protocols 

### 31 approached twice that of the S

- W protocols, e.g., 150 ppb versus 80 ppb peak 

### 32 concentration. At time intervals toward the end of an exposure, O 3 delivery rates for the 

### 33 triangular protocols were less than those of S

- W. At these later time intervals, there is 

### 34 some recovery of responses during triangular exposure protocols, whereas there is a 

### 35 continued development of or a plateau of responses in the S

- W exposure protocols. Thus, 

### 36 responses during triangular protocols relative to S

- W proto cols may be expected to 

### 37 diverge and be greater following peak exposures and then converge toward the end of an 

### 38Draft

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- 10 September 2011 exposure. The ensuing discussion on exposures between 40 and 80 ppb will focus on 

### 1 postexposure effects where the influence of triangular and S

- W concentration patterns are 

### 2 minimal, i.e., FEV 1 pre - to

- post effects are similar (although not identical) between 

### 3 triangular and S

- W protocols having equivalent average exposure concentrations. 

### 4 Schelegle et al. ( 2009 ) recently investigated the effects of 6.6 hours variable O 3 exposure 

### 5 protocols at mean concentrations of 60, 70, 80, and 87 ppb on respiratory symptoms and 

### 6 pulmonary function in young he althy adults (16 F, 15 M; 21.4 ± 0.6 years) exposed 

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

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

- exposure) were

- 0.80 ± 

### 9 0.90%, 2.72 ± 1.48%, 5.34 ± 1.42% , 7.02 ± 1.60%, and 11.42 ± 2.20% for exposure to 

### 10 FA, 60, 70, 80, and 87 ppb O 3 , respectively. Statistically significant decrements in FEV 1 

### 11 and increases in total subjective symptom scores (p < 0.05) were found following 

### 12 exposure to mean concentrations of 70, 80, and 87 ppb O 3 relative to FA. Statistically 

### 13 significant effects were not found at 60 ppb. One of the expressed purposes of the 

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

### 15 produces a statistically significant decrement in FEV 1 and symptoms in healthy 

### 16 individuals completing 6.6

- h exposure protocols. At 70 ppb, Schelegle et al. ( 2009 ) 

### 17 observed a statistically significant O 3 - induced of 6.1%. At 60 ppb, an O 3 - induced 3.5% 

### 18 FEV 1 decrement was not found to be statistically significant. However, this effect is 

### 19 similar in magnitude to the 2.9% FEV 1 decrement at 60 ppb observed by Adams ( 2006a ) 

### 20 that was found to be stat istically significant by Brown et al. ( 2008 )

. 

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

- h exposure to 60 ppb O 3 

### 22 during moderate quasi continuous exercise (V E = 40 L/min) on pulmonary function and 

### 23 respiratory symptoms in young healthy adults (32 F, 27 M; 25.0 ± 0.5 year) that were 

### 24 roug hly half GSTM1

- null and half GSTM1

- positive. Sputum neutrophil levels were also 

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

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

- exposure) were significantly 

### 27 differe nt (p = 0.008) between the FA (0.002 ± 0.46%) and O 3 (1.76 ± 0.50%) exposures. 

### 28 The inflammatory response following O 3 exposure was also significantly (p<0.001) 

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

### 30 exposure. Th ere was also no significant effect of GSTM1 genotype on FEV 1 or 

### 31 inflammatory responses. 

### 32 Consideration of the minimal O 3 concentration producing statistically significant effects 

### 33 on FEV 1 following 6.6

- h exposures warrants additional discussion. As discussed above, 

### 34 numerous studies have demonstrated statistically significant O 3 - induced group mean 

### 35 FEV 1 decrements of 6

- 8% at 80 ppb. Schelegle et al. ( 2009 ) have now reported 

### 36 statistically significant O 3 - induced group mean FEV 1 decrement of 6%, as well as 

### 37Draft

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- 11 September 2011 respiratory symptoms, at 70 ppb. At 60 ppb, there is information available from 4 

### 1 separate studies ( Adams, 1998 ) 1 ( Kim et al., 2011 ; Schelegle et al., 2009 ; Adams, 2006a )

. 

### 2 The group mean O 3 - induced FEV 1 decrements observed in these studies were 3.6% by 

### 3 Adams ( 1998 ) 2 , 2.8% (triangular exposure) and 2.9% (S

- W exposure) by Adams ( 2006a ) , 

### 4 3.5% by Schelegle et al. ( 2009 ) , and 1.8% by Kim et al. ( 2011 ) . Based on data from these 

### 5 four studies, at 60 ppb, the weighted

- average group me an O 3 - induced FEV 1 decrement 

### 6 (i.e., adjusted for FA responses) is 2.7% (n=150) ( Kim et al., 2011 ; Schelegle et al., 2009 ; 

### 7 Adams, 2006a , 1998 ) . Although not consistently statistically significant, these group 

### 8 mean changes in FEV 1 at 60 ppb are consistent between studies, i.e., none observed an 

### 9 average improvement in lung function following a 6.6

- h exposure to 60 ppb O 3 . Indeed, 

### 10 as was illustrated in Figure 6

- 1, the FEV 1 responses at 60 ppb fall on a smooth dose



### 11 response curve for exposures between 40 and 120 ppb O 3 . Furthermore, in a re

- analysis 

### 12 of the 60 ppb S

- W data from Adams ( 2006a ) , Brown et al. ( 2008 ) found the mean effects 

### 13 on FEV 1 to be highly statistically significant (p<0.002) using several common statistical 

### 14 tests even after removal of 3 potential outliers. The time

- course and magnitude of FEV 1 

### 15 responses at 40 ppb resemble those occurring during FA expos ures ( Adams, 2006a , 

### 16 2002 ) . Taken together, the available evidence shows that detectable effects of O 3 on 

### 17 group mean FEV 1 persist down to 60 ppb, bu t not 40 ppb in young healthy adults 

### 18 exposed for 6.6 hours during moderate exercise. 

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

### 20 responses, O 3 exposure also affects the function of the small airways and parenc hymal 

### 21 lung. Foster et al. ( 1997 ; 1993 ) examined the effect of O 3 on ventilation distribution. In 

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

### 23 intermittent exercise for 2 h), there was a significant reduction in ventilation to the lower 

### 24 lung (31% of lung v olume) and significant increases in ventilation to the upper

- and 

### 25 middle

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

### 26 25.4 ± 2 years old) exposed to O 3 (350 ppb with moderate intermittent exercise for 2.2 h), 

### 27 O 3 exposure caused a delayed gas washout ( Foster et al., 1997 ) . The pronounc ed slow 

### 28 phase of gas washout following O 3 exposure represented a 24% decrease in the washout 

### 29 rate. A day following O 3 exposure, 50% of the subjects still had (or developed) a delayed 

### 30 washout relative to the pre

- O 3 maneuver. These studies suggest a prolong ed O 3 effect on 

### 31 the small airways and ventilation distribution in healthy young individuals. 

### 32

1 The American Petroleum Institute has declined to provi de a copy of this report to EPA. 2 This information is from page 133 of Adams ( 2006a ) . This decrement may be increased due to a target V E of 23 L/min/m 2 BSA relative to other studies with wh ich it is listed having the target VE of 20 L/min/m 2 BSA. It should also be noted that subjects were exposed via a facemask in this study. However, Adams ( 2003a , b , 2002 ) found very similar FEV 1 responses between facemask and chamber exposures.Draft

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- 12 September 2011 There is a rapid recovery of O 3 - induced spirometric responses and symptoms; 40 to 65% 

### 1 recovery appears to occur within about 2 hours following exposure ( Folinsbee and 

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

- h exposure to 400 ppb O 3 with intermittent 

### 3 exercise, Nightingale et al. ( 2000 ) observed a 13.5% mean decrement in FEV 1 . By 3 

### 4 hours post exposure, however, only a 2.7% FEV 1 decrement persisted. Partial recovery 

### 5 also occurs following cessation of exercise despite continued exposure to O 3 ( Folinsbee 

### 6 et al., 1977 ) and at low O 3 concentrations during exposure ( Hazucha et al., 1992 ) . A 

### 7 slower recovery phase, especially after exposure to higher O 3 concentrations, may take at 

### 8 least 24 hours to complete ( Folinsbee and Hazucha, 2000 ; Folinsbee et al., 1993 )

. 

### 9 Repeated daily exposure studies at higher concentrations typically show that FEV 1 

### 10 response to O 3 is enhanced on the second day of exposure. This enhanced response 

### 11 suggests a residual effect of the previous exposure, about 22 hours earlier, even thoug h 

### 12 the pre

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

### 13 enhanced response with repeated exposure at lower O 3 concentrations may be the result 

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

. 

### 15 Intersubject Variability in Response of Healthy Subjects Consideration of group mean changes is important in discerning if observed effects are 

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

- individual variability in responses is, 

### 17 however, considerable and pertinent to assessing the fraction of the population that might 

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

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

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

### 21 un derstood to affect the spirometric and symptomatic responses to O 3 . Subsequently, 

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

- smokers and 

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

### 24 studies have documented considerable variability in responsiveness to O 3 even in subjects 

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

### 26 An individual ’ s FEV 1 response to a 2

- h O 3 exposure is generally reproducible over 

### 27 several months and presumably reflects the intrinsic responsiveness of the individual to 

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

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

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

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

- h exposures with intermittent 

### 32 exercise causing a predicted average FEV 1 decrement of 10%, indivi dual decrements 

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

- 36 years ( McDonnell et al., 

### 34 1997 ) . For an average FEV 1 decrement of 13%, Ultman et al. ( 2004 ) reported FEV 1 

### 35 responses ranging from a 4% improvement to a 56% decrement in young healthy adults 

### 36Draft

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- 13 September 2011 (32 M, 28 F) exposed for 1 hour to 250 ppb O 3 . One

- third of the subjects had FEV 1 

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

### 2

Source: Adapted with permission of American Thoracic Society ( Schelegle et al., 2009 ) 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. Subjects were exposed to a triangular ozone concentration profile having the average ozone concentration provided in each panel. As average ozone concentration increased, the distribution of resp onses 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%. 

### 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 - h exposures to ozone or filtered air.

Consistent with the 1

- to 2

- h studies, the distribution of individual responses following 

### 3 6.6

- h exposure studies becomes skewed with increasing exposure concentration and 

### 4 magnitude of the group mean FEV 1 response ( McDonnell, 1996 ) . Figure 6

- 2 illustrates 

### 5 frequency distributions o f individual FEV 1 responses observed in 31 young healthy adults 

### 6 following 6.6

- h exposures between 0 and 80 ppb. Schelegle et al. ( 2009 ) found >10% 

### 7 FEV 1 decrements in 16, 19, 29, and 42% of individuals exposed for 6.6 hours to 60, 70, 

### 8 80, and 87 ppb, respectively. Just as there are differences in mean decrements between 

### 9 studies having similar exposure scenarios (Figure 6

- 1 at 80 and 120 ppb), there a re also 

### 10 differences in the proportion of individuals affected with >10% FEV 1 decrements. At 

### 11 80 ppb, the proportion affected with >10% FEV 1 decrements was 17% (n=30) by Adams 

### 12 ( 2006a ) 1 , 26% (n= 60) by McDonnell ( 1996 ) , and 29%(n=31) by Schelegle et al. ( 2009 )

. 

### 13 At 60 ppb, the proportion with >10% FEV 1 decrements was 20% (n=30) by Adams 

### 14 ( 1998 ) 2 , 3% (n=30) by Adams ( 2006a ) 5 , 16% (n=31) by Schelegle et al. ( 2009 ) , and 5% 

### 15 (n=59) by Kim et al. ( 2011 ) . Based on these studies, the weighted average proportion of 

### 16

1 Not assessed by Adams ( 2006a ) , the proportion was provided in Figure 8
- 1B of U.S. EPA ( 2006b )

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

.Draft

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- 14 September 2011 individuals with >10% FEV 1 decrements is 10% following exposure to 60 ppb. Due to 

### 1 lim ited data within the published papers, these proportions were not corrected for 

### 2 responses to FA exposure where lung function typically improves in healthy adults. For 

### 3 example, uncorrected versus O 3 - induced (i.e., adjusted for response during FA exposure) 

### 4 p roportions of individuals having >10% FEV 1 decrements in the Adams ( 2006a ) 1 study 

### 5 were, respectively, 3% versus 7% at 60 ppb and 17% versus 23% at 80 ppb. Thus, 

### 6 uncorrected proportions undere stimate the actual fraction of healthy individuals affected. 

### 7 Given considerable inter

- individual variability in responses, the interpretation of 

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

### 9 prolonged 6.6

- h exposures t o an average level of 60 ppb O 3 , data available from four 

### 10 studies yield a weighted

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

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

### 12 2006a , 1998 ) . The data from these studies also yield a weighted

- average proportion 

### 13 (uncor rected for FA responses) of subjects with >10% FEV 1 decrements of 10% (n=150) 

### 14 ( Kim et al., 2011 ; Schelegle et al., 2009 ; Adams, 2006a , 1998 ) . In an individual with 

### 15 relatively “ normal ” lung function, recognizing technical and biological variability in 

### 16 measurements, confidence can be given that within

- day changes in FEV 1 of ≥ 5% are 

### 17 clinically meaningful ( Pellegrino et al., 2005 ; ATS, 1991 ) . Here focus is given to 

### 18 individuals with >10% decrements in FEV 1 since some individuals in the Schelegle et al. 

### 19 ( 2009 ) study experienced 5

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

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

### 21 criterion for assessing exercise

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

### 22 2000a ) . The data are not available in the published papers to determine the O 3 - induced 

### 23 proportion for either the Adams ( 1998 ) or Schelegle et al. ( 2009 ) studies. As already 

### 24 stated, however, this uncorrected proportion likely underestimates that actual proportion 

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

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

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

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

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

### 30 only Kim et al. ( 2011 ) reported FEV 1 decreme nts at 60 ppb to be statistically significant. 

### 31 Although, Brown et al. ( 2008 ) found tho se from Adams ( 2006a ) to be highly statistically 

### 32 significant. Though group mean decrements are biologically small and generally do not 

### 33 attain statistical significance, a considerable fraction of exposed individuals experience 

### 34 clinically meaningful decrements in lung function. 

### 35

1 Not assessed by Adams ( 2006a ) , uncorrected and O 3
- induced proportions are from Figures 8
- 1B and 8
- 2, respect ively, of the 2006 O 3 AQCD ( 2006b )

.Draft

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- 15 September 2011 Responses in Individuals with Pre - Existing Disease Individuals with respiratory disease are of primary concern in evaluating the health 

### 1 effects of O 3 because a given chan ge in function is likely to have more impact on a 

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

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

### 4 moderate exercise do not generally experience statistica lly significant pulmonary 

### 5 function decrements following 1

- and 2

- h exposures to ≤ 300 ppb O 3 ( Kehrl et al., 1985 ; 

### 6 Linn et al., 1983 ; Linn et al., 1982b ; Solic et al., 1982 ) . Following a 4

- hour exposure to 

### 7 240 ppb O 3 during exercise , Gong et al. ( 1997b ) found an O 3 - induced FEV 1 decrement of 

### 8 8% in COPD patients which was not statistically different from the decrement of 3% in 

### 9 heal thy subjects. Demonstrating the need for control exposures and presumably due to 

### 10 exercise, four of the patients in the Gong et al. ( 1997b ) study had F EV 1 decrements of 

### 11 >14% following both the FA and O 3 exposures. Although the clinical significance is 

### 12 uncertain, small transient decreases in arterial blood oxygen saturation have also been 

### 13 observed in some of these studies. 

### 14 Based on studies reviewed in th e 1996 and 2006 O 3 AQCDs, asthmatic subjects appear to 

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

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

- to

- moderate asthmatics to be 

### 17 significantly larger than in healthy subjects (19% versus 10%, respectively) exposed to 

### 18 160 ppb O 3 during exercise for 7.6

- h exposure. In asthmatics, a significant positive 

### 19 corre lation between O 3 - induced spirometric responses and baseline lung function was 

### 20 observed, i.e., responses increased with severity of disease. Such differences in 

### 21 pulmonary function between asthmatics and healthy individuals were not found in shorter 

### 22 duratio n studies. Alexis et al. ( 2000 ) and Jörres et al. ( 1996 ) reported a tendency for 

### 23 slightly greater FEV 1 decrements in asthmatics than healthy subjects. Several studies 

### 24 reported similar responses between asthmatics and healthy individuals ( Scannell et al., 

### 25 1996 ; Hiltermann et al., 1995 ; Basha et al., 1994 ) . The lack of differences in the 

### 26 Hiltermann et al. ( 1995 ) and Basha et al. ( 1994 ) studies was not surprising, however, 

### 27 given extremely small sample s izes and corresponding lack of statistical power. One 

### 28 study reported a tendency for asthmatics to have smaller O 3 - induced FEV 1 decrements 

### 29 than healthy subjects (3% versus 8%, respectively) when exposed to 200 ppb O 3 for 2 

### 30 hours during exercise ( Mudway et al., 2001 ) . However, the asthm atics in that study also 

### 31 tended to be older than the healthy subjects, which could partially explain their lesser 

### 32 response since FEV 1 responses to O 3 diminish with age. 

### 33 Some, but not all, studies have also reported that asthmatics have a somewhat 

### 34 exaggera ted airway inflammatory response to acute O 3 exposure relative to healthy 

### 35 control subjects ( Holz et al., 2002 ; Peden, 2001 ; Newson et al., 2000 ; Hiltermann et al., 

### 36Draft

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- 16 September 2011 1999 ; Michelson et al., 1999 ; Vagaggini et al., 1999 ; Hiltermann et al., 1997 ; Peden et 

### 1 al., 1997 ; Scannell et al., 1996 ; Peden et al., 1995 ; Basha et al., 1994 ; McBride et al., 

### 2 1994 ) . For example, at 18 hours post

- O 3 exposure (200 ppb, 4 hours with exercise) and 

### 3 cor rected for FA responses, Scannell et al. ( 1996 ) found significantly increased 

### 4 neutrophils in 18 asthmatics (12%) compared to 20 healthy subjects (4.5%). This 

### 5 difference in inflammatory response was observed despite no group differences in 

### 6 spirometric respo nses to O 3 . 

### 7 Vagaggini et al. ( 2010 ) exposed mild

- to

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

### 8 300 ppb O 3 for 2 hours with moderate exercise. Although the group mean O 3 - induced 

### 9 FEV 1 decrement was only 4%, eight subjects were categorized as “ responders ” with 

### 10 >10% FEV 1 decrements. There were no baseline differences between responders and 

### 11 nonresponders. At 6 hours post O 3 exposure, sputum neutrophils were significantly 

### 12 increased by 15% relative to FA in responders. The neutrophil increase in responders was 

### 13 also significantly greater than the 0.2% increase in nonresponders. Across all subjects, 

### 14 there was a significant (r=0.61, p = 0.015) correlation between changes in FEV 1 and 

### 15 changes in sputum neutrophils. Prior studies have reported that inflammatory responses 

### 16 do not appear to be correlated with lung function responses in either asthmatic or healthy 

### 17 subjects ( Holz et al., 1999 ; Balmes et al., 1997 ; Balmes et al., 1996 ; Devlin et al., 1991 )

. 

### 18 Interestingly, th e nonresponders in the Vagaggini et al. ( 2010 ) study experienced a 

### 19 significant O 3 - induced 11.3% increase in sputum eosinophils, while responders had an 

### 20 nonsignificant 2.6% decrease. Six of the su bjects were NQO1 wild type and GSTM1 null , 

### 21 but this genotype was not found to be associated with the changes in lung function or 

### 22 inflammatory responses to O 3 . 

### 23 A few recent studies have evaluated the effects of corticosteroid usage on the response of 

### 24 asthma tics to O 3 . Vagaggini et al. ( 2007 ) evaluated whether corticosteroid usage would 

### 25 prevent O 3 - induced lung function decrements and inflammatory responses in a group of 

### 26 subjects with mild persistent asthma (n=9; 25 ± 7 years). In this study, asthmatics were 

### 27 randomly exposed on four occasions t o 270 ppb O 3 or FA for 2 hours with moderate 

### 28 exercise. Exposures were preceded by four days of treatment with prednisone or placebo. 

### 29 Pretreatment with corticosteroids prevented an inflammatory response in induced sputum 

### 30 at 6 hours postexposure. FEV 1 respon ses were, however, not prevented by corticosteroid 

### 31 treatment and were roughly equivalent to those observed following placebo. Vagaggini et 

### 32 al. ( 2001 ) al so found budesonide to decrease airway neutrophil influx in asthmatics 

### 33 following O 3 exposure. In contrast, inhalation of corticosteroid budesonide failed to 

### 34 prevent or attenuate O 3 - induced responses in healthy subjects as assessed by 

### 35 measurements of lung f unction, bronchial reactivity and airway inflammation 

### 36 ( Nightingale et al., 2000 ) . High doses of inhaled flu ticasone and oral prednisolone have 

### 37Draft

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- 17 September 2011 each been reported to reduce inflammatory responses to O 3 in healthy individuals ( Holz 

### 1 et al., 2005 )

. 

### 2 More recently, Stenfors et al. ( 2010 ) exposed persistent asthmatics (n=13; aged 33 years) 

### 3 receiving chronic inhaled corticosteroid therapy to 200 ppb O 3 for 2 hours with moderate 

### 4 exercise. An average O 3 - induced FEV 1 decrement of 8.4% was observed, whereas, only a 

### 5 3.0% FEV 1 decrement is predicted for similarly ex posed age

- matched healthy controls 

### 6 ( McDonnell et al., 2007 ) . At 18 hours postexposure, there was a significant O 3 - induced 

### 7 increase in bronchioalveolar lavage (BAL) neutrophils, but not eosinophils. Bronchial 

### 8 biopsy also showed a significant O 3 - induced increase in mast cells. This study suggests 

### 9 that the protective effect of acute corticosteroid therapy against inflammatory responses 

### 10 to O 3 in asthmatics demonstrated by Vagaggini et al. ( 2007 ) may be lost with continued 

### 11 treatment regimes. 

### 12
Factors Modifying Responsiveness to Ozone Physical activity increases V E and therefore the dose of inhaled O 3 . Consequently, the 

### 13 intensity of physiological response during and following an acute O 3 exposure will be 

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

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

- level factors, such as 

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

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

### 18 exposures. 

### 19 Children, adolescents, and young adults (<18 years of age) a ppear, on average, to have 

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



### 21 aged and older adults when exposed to comparable O 3 doses ( U.S. EPA, 1996a )

. 

### 22 Symptomatic responses to O 3 exposure, however, appear to increase with age until early 

### 23 adulthood and then gradually decrease with increasing age ( U.S. EPA, 1996a ) . For 

### 24 example, healthy children (aged 8

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

### 25 exercise) experienced similar spirometric responses but lesser symptoms than similarly 

### 26 exposed young healthy adults ( McDonnell et al., 1985b ) . For subjects aged 18

- 36 years, 

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

### 28 decrease with increasing age. Diminished symptomatic responses in children a nd the 

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

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

### 31 development reaches the peak (18

- 20 years of age in females and early twe nties in 

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

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

### 34Draft

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- 18 September 2011 In healthy individuals, the fastest rate of decline in O 3 responsiveness appears between 

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

### 2 females then mal es ( Hazucha et al., 2003 )

. During the middle age period (35

- 55 years), 

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

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

- dependent 

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

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

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

### 8 decrease with age beyond young adulthoo d, this evidence comes from cross

- sectional 

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

### 10 Several studies have suggested that physiological differences between sexes may 

### 11 predispose females to a greater susceptibility to O 3 . In females, lower plasma and nasal 

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

### 13 mechanism of O 3 neutralization in airway surface liquid, may be a contributing factor 

### 14 ( Housley et al., 1996 ) . Consequently, reduced absorption of O 3 in the upper airways ma y 

### 15 promote its deeper penetration. Dosimetric measurements have shown that the absorption 

### 16 distribution of O 3 is independent of gender when absorption is normalized to anatomical 

### 17 dead space ( Bush et al., 1996 ) . Thus, a gender

- related differential removal of O 3 by uric 

### 18 acid seems to be minimal. In general, the physiologic response of young healthy females 

### 19 to O 3 exposure appears comparable to the response of young males ( Hazucha et al., 

### 20 2003 ) . Several studies have investigated the effects of the menstrual cycle on responses to 

### 21 O 3 in healthy young women. In a study of 9 women exposed during exercise to 300 ppb 

### 22 O 3 for an hour, Fox et al. ( 1993 ) found lung function responses to O 3 significantly 

### 23 enhanced during the follicular phase relative to the luteal phase. However, Weinmann et 

### 24 al. ( 1995a ) found no difference in responses between the follicular and luteal phases as 

### 25 well as no significant differences between 12 males and 12 females exposed during 

### 26 exercise to 350 ppb O 3 for 2.15 h. Seal et al. ( 1996 ) also reported no effect of menstrual 

### 27 cycle phase in their analysis of responses of 150 women (n=25 per exposure group; 0, 

### 28 120, 240, 300, and 400 ppb O 3 ). Seal et al. ( 1996 ) conceded that the methods used by Fox 

### 29 et al. ( 1993 ) more precisely defined menstrual cycle phase. 

### 30 Only two controlled human exposure studies have assessed differences in lun g function 

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

### 32 (93 M, 94 F) and blacks (undefined ancestry; 92 M, 93 F) exposed to a range of O 3 

### 33 concentrations (0

- 400 ppb). The main effects of gender

- race group and O 3 concentra tion 

### 34 were statistically significant (both at p < 0.001), although the interaction between gender



### 35 race group and O 3 concentration was not significant (p = 0.13). These findings indicate 

### 36 some overall difference between the gender

- race groups that is independ ent of O 3 

### 37 concentration, i.e., the concentration

- response curves for the four gender

- race groups are 

### 38Draft

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- 19 September 2011 parallel. In a multiple comparison procedure on data collapsed across all O 3 

### 1 concentrations for each gender

- race group, both black men and black women had 

### 2 significantly larger decrements in FEV 1 than did white men. The authors noted that the 

### 3 O 3 dose per unit of lung tissue would be greater in blacks and females than whites and 

### 4 males, respectively. That this difference in tissue dose might have affected respo nses to 

### 5 O 3 cannot be ruled out. The college students recruited for the Seal et al. ( 1993 ) study are 

### 6 probably from better educated and SES advantaged families, thus reducing potential 

### 7 influence of these variables on results. In a follow

- up analysis, Seal et al. ( 1996 ) reported 

### 8 that, of three SES categories, individuals in the middle SES category showed greater 

### 9 concentration

- dependent decline in percent

- predicted FEV 1 (4

- 5% at 400 ppb O 3 ) than 

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

### 11 for this finding. 

### 12 More recently, Que et al. assessed pulmonary responses in blacks of African American 

### 13 ancestry (22 M, 24 F) and Caucasians (55 M, 28 F) exposed to 220 ppb O 3 for 2.25 h 

### 14 (alternating 15 min periods of rest and brisk treadmill walking). On average, the black 

### 15 males experienced a 16.8% decrement in FEV 1 following O 3 exposure which was 

### 16 significantly larger than mean FEV 1 decrements of 6.2, 7.9, and 8.3% in black females 

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

### 18 ( 1993 ) , there w as potential that the increased FEV 1 decrements in blacks relative to 

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

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

### 21 Que et al. study, however, since exercise rates were normalized to lung volume (viz., 6

- 8 

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

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

### 24 Smokers are less responsive to O 3 than nonsmokers. Spirometric and plethysmographic 

### 25 pulmonary function decline, nonspecific air way hyperreactivity, and inflammatory 

### 26 response of smokers to O 3 were all weaker than data reported for nonsmokers. Although 

### 27 all of these responses are intrinsically related, the functional association between them, as 

### 28 in nonsmokers, has been weak. Similarl y, the time course of development and recovery 

### 29 of these effects as well their reproducibility was not different from nonsmokers. Chronic 

### 30 airway inflammation with desensitization of bronchial nerve endings and an increased 

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

### 32 relative to nonsmokers ( Frampton et al., 1997b ; Torres et al., 1997 )

. 

### 33 The first line of defense against oxidative stress is antioxidants

- rich ELF which 

### 34 scavenges free radicals and limit lipid peroxidation. Exposure to O 3 depletes the 

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

### 36 however, the concen tration and the activity of antioxidant enzymes either in ELF or 

### 37Draft

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- 20 September 2011 plasma do not appear to be related to O 3 responsiveness ( Samet et al., 2001 ; Avissar et 

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

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

- tocopherol and 

### 3 ascorbate on spirometric lung function from O 3 but not on the intensity of subjective 

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

### 5 of mediators ( Samet et al., 2001 ; Trenga et al., 2001 ) . Dietary antiox idants have also been 

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

### 7 al., 2001 )

. 

### 8 A number of studies (e.g., Romieu et al., 2004a ; David et al., 2003 ; Corradi et al., 2002 ; 

### 9 Bergamaschi et al., 2001 ) have reported that genetic polymorphisms of antioxidant 

### 10 enzymes may modulate pulmonary function and inflammatory response to O 3 challenge. 

### 11 It appears that healthy carriers of NQO1 wild type in combination with GSTM1 null 

### 12 genotype are more responsive to O 3 . Adults with GSTM1 null only genotype did not 

### 13 show O 3 hyperresponsiveness. In contrast, asthmatic children with GSTM1 null genotype 

### 14 ( Romieu et al., 2004a ) were reported to be more responsive to O 3 . However, in a 

### 15 controlled exposure of mild

- to

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

### 16 for 2 hours with moderate exercise, Vagaggini et al. ( 2010 ) found that six of the subjects 

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

### 18 in lung function or inflammatory responses to O 3 . 

### 19 Kim et al. ( 2011 ) also recently reported that GSTM1 genotype was not predictive of 

### 20 FEV 1 responses in young healthy adults (32 F, 27 M; 25.0 ± 0.5 year) that were roughly 

### 21 half GSTM1

- null and half GSTM1

- sufficient. Sputum neutrophil levels, measured in a 

### 22 subset of the subjects (13 F, 11 M), were also not significantly associated with GSTM1 

### 23 gen otype. 

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

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

### 26 ( 2009 ) found that inflammatory responses but not lung function responses to O 3 were 

### 27 dependent on ge notype. At 4 hours post O 3 exposure, both GSTM1 genotype groups had 

### 28 significant increases in sputum neutrophils with a tendency for a greater increase in 

### 29 GSTM1 sufficient than nulls. At 24 h postexposure, sputum neutrophils had returned to 

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

### 31 however, sputum neutrophil levels increased from 4 h to 24 h and were significantly 

### 32 greater than both baseline levels and levels at 24 h in the GSTM1 sufficient individuals. 

### 33 Since there was n o FA control in the Alexis et al. ( 2009 ) study, effects of the exposure 

### 34 other than O 3 itself cannot be ruled out. In general, the findings between studies are 

### 35 inconsistent. Additional studies that include control exposures are needed to clarify the 

### 36 influence of genetic polymorph isms on O 3 responsiveness. 

### 37Draft

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- 21 September 2011 In a retrospective analysis of data from 541 healthy, nonsmoking, white males between 

### 1 the ages of 18

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

### 2 Facility in Chapel Hill, North Carolina, McDonnell et al. ( 2010 ) found that increased 

### 3 body mass index (BMI) was associated with enhanced FEV 1 responses. The BMI effect 

### 4 was of the same order of magnitude but in the opposite direc tion of the age effect where 

### 5 by FEV 1 responses diminish with increasing age. In a similar retrospective analysis, 

### 6 Bennett et al. ( 2007 ) found enhanced FEV 1 decrements following O 3 exposure with 

### 7 increasing BMI in a group of 75 healthy, nonsmoking, women (age 24 ± 4 years; BMI 

### 8 range 15.7 to 33.4 ), but not 122 healthy, nonsmoking, men (age 25 ± 4 years; BMI range 

### 9 19.1 to 32.9). In the women, greater O 3 - induced FEV 1 decrements were seen in 

### 10 overweight (BMI >25) than in normal weight (BMI from 18.5 to 25), and in normal 

### 11 weight than in underweight (BM I <18.5) (P trend ≤ 0.022). Together, these results 

### 12 indicate that higher BMI may be a risk factor for pulmonary effects associated with O 3 

### 13 exposure. 

### 14
Repeated Ozone Exposure Effects Based on studies reviewed in previous O 3 AQCDs, several conclusions can be drawn 

### 15 about repeated 1to 2 h O 3 exposures. Repeated exposures to O 3 causes enhanced (i.e., 

### 16 greater decrements) FVC and FEV 1 responses on the second day of exposure. The 

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

### 18 resp onse ( Horvath et al., 1981 ) . Small responses to the first O 3 exposure are less likely to 

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

. 

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

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

### 22 fifth days of repeated O 3 exposure. This attenuation of responses is lost in 1 week ( Kulle 

### 23 et al., 1982 ; Linn et al., 1982a ) or perhaps 2 weeks ( Horvath et al., 1981 ) without O 3 

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

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

### 26 the second exposure day and attenuated with repeated O 3 exposure thereafter ( Folinsbee 

### 27 et al., 1998 ; Foxcroft and Adam s, 1986 ; Linn et al., 1982a ; Folinsbee et al., 1980 ) . In 

### 28 longer

- duration (4

- 6.6 hours), lower

- concentration studies that do not cause an enhanced 

### 29 second

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

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

. 

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

### 32 to be significantly attenuated following four consecutive days of exposure to O 3 (250 

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

### 34 of isovolumetric FEF 25

- 75 , Vmax 50 and Vmax 75 ) showed a persistent functional reduction 

### 35 from Day 2 through Day 4. Notably, in contrast to FVC and FEV 1 which exhibited a 

### 36Draft

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- 22 September 2011 recovery of function between days, there was a persistent effect of O 3 on small airways 

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

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

### 3 significantly higher following O 3 (24 h after last O 3 exposure) compared to FA. 

### 4 Inflammatory markers from bronchioalveolar lavage fluid (BALF) following 4 

### 5 consecutive days of both 2

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

- h ( Jorres et al., 2000 ; Christian et 

### 6 al., 1998 ) exposures have indicated ongoing cellular damage irrespective of the 

### 7 attenuation of some cellular inflammatory responses of the airways, lung function and 

### 8 symptoms response. These data suggest that the persistent small airways dysfu nction 

### 9 assessed by Frank et al. ( 2001 ) is likely induced by both neurogenic and inflamm atory 

### 10 mediators, since the density of bronchial C

- fibers is much lower in the small than large 

### 11 airways. 

### 12
Summary of Controlled Human Exposure Studies on Lung Function Responses in humans exposed to ambient O 3 concentrations include: decreased 

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

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

. 

### 15 Discussed in subseq uent Sections 6.2.2.1 and 6.2.3.1, exposure to O 3 also results in 

### 16 airway hyperresponsiveness, pulmonary inflammation, immune system activation, and 

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

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

### 19 bronchoconstriction, contributes to a decrease in the FEV 1 . Healthy young adults exposed 

### 20 to O 3 concentrations ≥ 60 ppb develop statistically significant reversible, transient 

### 21 decrements in lung function if minute ventilation or duration of exposure is increased 

### 22 sufficiently. With repeated O 3 exposures over several days, FEV 1 and symptom responses 

### 23 become attenuated in both healthy individuals and asthmatics, but this tolerance is lost 

### 24 after about a week without exposure ( Gong et al., 1997a ; Fol insbee et al., 1994 ; Kulle et 

### 25 al., 1982 ) . In contrast to the attention of FEV 1 responses, there appear to be persistent O 3 

### 26 effects on small airways function as well as ongoing cellular damage during repeated 

### 27 exposures. 

### 28 There is a large degree of intersubject variability in lung function decrements 

### 29 ( McDonnell, 199 6 ) . However, these lung function responses tend to be reproducible 

### 30 within a given individual over a period of several months indicating differences in the 

### 31 intrinsic responsiveness of individuals ( Hazucha et al., 2003 ; McDonnell et al., 1985a ) . In 

### 32 healthy young adults, O 3 - induced decrements in FEV 1 do not appear to depend on gender 

### 33 ( Hazucha et al., 2003 ) , body surface area or height ( McDonnell et al., 1997 ) , lung size or 

### 34 baseline FVC ( Messineo and Adams, 1990 ) . There is limited evidence that blacks may 

### 35 experience greater O 3 - induced decrem ents in FEV 1 than age

- matched whites ( Que et al. ; 

### 36Draft

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- 23 September 2011 Seal et al., 1993 ) . Healthy children experience similar spirometric responses but lesser 

### 1 symptoms from O 3 exposure relative to young adults ( McDonnell et al., 1985b ) . On 

### 2 average, spirometric and symptom responses to O 3 exposure appear to decline with 

### 3 increasing age beyond about 18 years of age ( McDonnell et al. , 1999 ; Seal et al., 1996 )

. 

### 4 There is a tendency for slightly increased spirometric responses in mild asthmatics and 

### 5 allergic rhinitics relative to healthy young adults ( Jorres et al., 1996 ) . Spirometric 

### 6 responses in asthmatics appear to be affected by baseline lung function, i.e., responses 

### 7 increase wi th disease severity ( Horstman et al., 1995 )

. 

### 8 Available information on recovery of lung function following O 3 exposure 

### 9 indicates that an initial phase of recovery in healthy individuals proceeds relatively 

### 10 rapidly, with acute spirometric and symptom responses resolving within about 2 to 4 h 

### 11 ( Folinsbee and Hazucha, 1989 ) . Small residual lung function effects are almost 

### 12 completely resolved within 24 h. One day following O 3 exposure, persisting effects on 

### 13 the small airways assessed by decrement s in FEF 25

- 75 and altered ventilation distribution 

### 14 have been reported ( Frank et al., 2001 ; Foster et al., 1997 )

. 

### 15

6.2.1.2 Epidemiology
The O 3 - induced lung function decrements consistently demonstrated in controlled human 

### 16 exposure studies (Section 6.2.1.1) provide biological plausibility for the epidemiologic 

### 17 evidence p resented in the 1996 and 2006 O 3 AQCDs, in which short

- term ambient O 3 

### 18 exposure was consistently associated with lung function decrements in diverse 

### 19 populations ( U.S. EPA, 2006b , 1996a ) . Coherence between the two disciplines was found 

### 20 not only for effects observed in groups with higher expected personal O 3 exposures and 

### 21 higher exertion levels, including children attending summer camps and adults exercising 

### 22 or working outdoors, but also for effects observed in children and individu als with pre



### 23 existing respiratory disease such as asthma ( U.S. EPA, 2006b , 1996a ) . Recent 

### 24 epidemiologic studies focused more on children with asthma rather than on groups with 

### 25 increased outdoor exposures or other healthy populati ons. Whereas a majority of recent 

### 26 studies conducted in children with asthma indicated decreases in lung function in 

### 27 association with increases in ambient O 3 exposure, recent studies in adults with asthma 

### 28 and individuals without asthma found both O 3 - associa ted decreases and increases in lung 

### 29 function. Recent studies also provided additional data to assess whether particular lags of 

### 30 O 3 exposure were more strongly associated with decrements in lung function; whether O 3 

### 31 associations were confounded by copolluta nt exposures; and whether risk was affected by 

### 32 factors such as corticosteroid (CS) use, genetic polymorphisms, elevated BMI, and diet. 

### 33Draft

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- 24 September 2011 

### Table 6 - 1 Mean and upper percentile concentrations of ozone in epidemiologic studies examining lung function in populati ons with increased outdoor exposures Study Location Years/Season O 3 Averaging Time Mean/Median Concentration (ppb) Upper Percentile Concentrations (ppb) Korrick et al. ( 1998 ) Mt. Washington, NH 1991, 1992 Warm season Hike
- time avg (2
- 12 h) 40 Max: 74
Thurston et al. ( 1997 ) Connecticut River Valley, CT 1991
- 1993 Warm season 1
- h max 83.6 Max: 160 Spektor et al. ( 1988b ) Tuxedo, NY 198 5 Warm season 1
- h avg NR Max: 124 Spektor et al. ( 1988a ) Fairview Lake, NJ 1984 Wa rm season 1
- h avg a 53 Max (1
- h max): 113 Spektor and Lippmann ( 1991 ) Fairview Lake, NJ 1988 Warm season 1
- h avg a 69 Max (1
- h max): 137 Berry et al. ( 1991 ) Hamilton, NJ July 1988 1
- h max NR Max: 204 Neas et al. ( 1999 ) Philadelphia, PA 1993 Warm season 12
- h a vg (9:00 a.m. 9:00 p.m.) 57.5 (Camp 1) 55.9 (Camp 2) Max (Camp 1): 106 Girardot et al. ( 2006 ) Great Smoky Mountain NP , TN 2002
- 2003 Warm season Hike
- time avg (2
- 9 h) 48.1 b Max: 74.2 b Selwyn et al. ( 1985 ) Houston, TX 1981 Warm season 15
- min max 47 Max: 135 Thaller et al. ( 2008 ) Galveston, TX 2002
- 2004 Warm season 1
- h max 35 (median) Max: 118 Higgins et al. ( 1990 ) San Bernardino, CA 1987 Warm season 1
- h avg a 123 Max: 245 Avol et al. ( 1990 ) Idyllwild, CA 1988 Warm season 1
- h avg a 94 Max: 161 Burnett et al. ( 1990 ) Lake Couchiching, Ontario, CA 1983 Warm season 1
- h avg a 59 Max: 95
Raizenne et al. ( 1989 ) Lake Erie, Ontario, CA 1986 Warm season 1
- h avg a 71 Max (1
- h max): 143
Brauer et al. ( 1996 ) British Columbia, Canada 1993 Warm season 1
- h max 40 Max: 84 Castillejos et al. ( 1995 ) Mexico City, Mexico June 1990
- October 1991 1
- h max 179 Max: 365 Romieu et al. ( 1998a ) Mexico City, Mexico March
- August 1996 Work shift avg (6
- 12 h) 67.3 95th: 105.8 Nickmilder et al. ( 2007 ) S outhern Belgium 2002 Warm season 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 Brunekreef et al. ( 1994 ) Netherlands 1981 Warm season Exercise
- time avg (10
- 145 min) 42.8 c Max: 99.5 c Hoek et al. ( 1993 ) Wageningen, Netherlands 1989 Warm season 1
- h max NR Max: 122 c Braun
- Fahrlander et al. ( 1994 ) S outhern Switzerland 1989 Warm season 30
- min avg NR Max: 80 c Hoppe et al. ( 1995 ) ; Hoppe et al. ( 2003 ) Munich, Germany 1992 Warm season 30
- min max (1:00 p.m.
- 4:00 p.m.) High O 3 days: 65.9 Control O 3 days: 27.2 Max (high O 3 days): 86
Chan et al. ( 2005 ) Taichung City, Taiwan 2001 Cold season 8
- h avg (9:00 a.m.
- 5:00 p.m.) 35.6 Max: 65.1 Max = Maximum; NR = not reported a 1
- h avg, preceding lung function measurement. b Individual
- level exposure estimates were derived based on time
- activity diary data. c Concentrations were converted from μg/m 3 to ppb using the conversion factor of 0.51 assuming standard temperature (25°C) a nd pressure (1 atm).Draft

– Do Not Cite or Quote 6
- 25 September 2011 Populations with Increased Outdoor Exposures Few epidemiologic studies characterizing acute O 3 - related respiratory morbidity have 

### 1 accounted for time spent outdoors, which may be an important determinant of 

### 2 interindividual variability in personal O 3 exposure. Among epidemiologic studies, studies 

### 3 of individuals engaged in outdoor recreation, exercise, or work are more comparable to 

### 4 controlled exposure studies because of improved estimates O 3 exposures, measurement of 

### 5 lung function before and after discrete periods of outdoor activity, and examination of O 3 

### 6 effects during exertion when the dose of O 3 reaching the lungs may be higher because of 

### 7 higher ventilation and inhalation of larger volumes of air. Characteristics and ambient O 3 

### 8 concen tration data from epidemiologic studies of populations with increased outdoor 

### 9 exposures are presented in Table 6

- 1. Similar to findings from controlled human 

### 10 exposure studies, the collective body of epidemiologic evidence clearly demonstrates 

### 11 decrements in lung function in association with O 3 exposures during periods of outdoor 

### 12 activity or exercise of varying intensity and duration (15 minutes to 12 hours) (Figures 6

- 

### 13 3 to 6

- 5 and Tables 6

- 2 to 6

- 4). 

### 14 Children Attending Summer Camps Studies of children attending summer camps, most of which were discussed in the 1996 

### 15 O 3 AQCD, have provided important understanding of the impact of ambient O 3 exposure 

### 16 on respiratory effects in young, healthy children. These studies were noted for their on



### 17 site measurement of ambient O 3 and daily assessment of lung function by trained staff 

### 18 over 1

- to 2

- week periods ( Thurston et al., 1997 ; Berry et al., 1991 ; Spektor and 

### 19 Lippmann, 1991 ; Avol et al., 1990 ; Burnett et al., 1990 ; Higgins et al., 1990 ; Raizenne et 

### 20 al., 1989 ; Spektor et al., 1988a ; Raizenne et al., 1987 )

. 

### 21 In groups mostly comprising healthy childr en (ages 7

- 17 years), decrements in FEV 1 

### 22 were found to be associated consistently with ambient O 3 exposures averaged over the 

### 23 1

- 8 hours preceding lung function measurement (Figure 6

- 3 and Table 6

- 2). Kinney et al. 

### 24 ( 1996 ) corroborat ed this association in a reanalysis combining 5367 lung function 

### 25 measurements collected from 616 healthy children from six studies ( Spektor and 

### 26 Lippmann, 1991 ; Avol et al., 1990 ; Burnett et al., 1990 ; Higgins et al., 1990 ; Spektor et 

### 27 al., 1988a ; Raizenne et al., 1987 ) . Based on uniform statistical methods, a 40

- ppb 

### 28 increase in concurrent

- hour O 3 exposure was associated with a

- 20 ml (95% CI:

- 25,

- 14) 

### 29 change in afternoon FEV 1 1 ( Kinney et al., 1996 ) . In these studies conducted in locations 

### 30

1 To facilitate comparisons among epidemiologic studies, for all health endpoints in Chapter 6, effect estimates are presented in terms of a standard increment in ambient O 3 concentration, one fo r each of the three commonly examined O 3 averaging times (1
- h max, 8
- h max, and 24
- h average). These standard increments are 40 ppb, 30 ppb, and 20 ppb for 1
- h max, 8
- h max, and 24
- h avg O 3 , respectively, and are based on annual mean to 95th percentile dif ferences that are representative of measurements from nationwide O 3 monitors in U.S. Metropolitan Statistical Areas as described in detail in Section 7.1.3.2 of the 2006 O 3 AQCD ( U.S. EPA, 2006b )

.Draft

– Do Not Cite or Quote 6
- 26 September 2011 across the Northeast U.S. and Canada and Calif ornia (Table 6

- 1) with varying pollutant 

### 1 mix, a wide range in effect estimates was found. Study

- specific effect estimates ranged 

### 2 between a 0.76 and 48 ml decrease or a 0.3% to 2.2% decrease in study mean FEV 1 . 

### 3 Associations between ambient O 3 exposure and p eak expiratory flow (PEF) in camp 

### 4 studies were more variable than were those with FEV 1 , as indicated by the wider range in 

### 5 effect estimates and wider 95% CIs (Figure 6

- 3 and Table 6

- 2). Nonetheless, most effect 

### 6 estimates indicated decreases in PEF in assoc iation with ambient O 3 exposure. The 

### 7 largest effect (mean 2.8% decline per 40

- ppb increase in 1

- h max O 3 ) was estimated in a 

### 8 group of campers with asthma ( Thurston et al., 1997 ) . In this study, O 3 also was 

### 9 associated with increases in chest symptoms and bronchodilator use, suggesting that the 

### 10 observed decreases in PEF may have been indicative of clinically significant effects. 

### 11

Effect estimates are from single
- pollutant models and are standardized to a 40
- ppb increase for 1
- h avg or 1
- h max ozone exposures and a 30
- ppb increase for 12
- h avg ozone exposures. 

### Figure 6 - 3 Changes in FEV 1 

### (ml) or PEF (ml/sec) in association with ambient ozone exposur e in studies of children attending summer camp
. Study FEV 1 (ml) Spektor et al. (1988a) Spektor and Lippmann (1991) Raizenne et al. (1987) 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 standardized increment in O 3 (95% CI) PEF (ml/sec) Spektor et al. (1988a) Raizenne et al. (1987) 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 standardized increment in O 3 (95% CI)Draft

– Do Not Cite or Quote 6
- 27 September 2011 

### Table 6 - 2 Additional characteristics and quantitative data for studies represented in Figure 6 - 3 Study Location Population Standardized percent change (95% CI) a Standardized effect estimate (95% CI) a FEV 1 (ml) Spektor et al. ( 1988a ) Fairview Lake, NJ Campers without asthma
- 0.93 (
- 1.5,
- 0.35)
- 20.0 (
- 32.5,
- 7.5) Spektor and Lippmann ( 1991 ) Fairview Lake, NJ Campers without asthma
- 2.2 (
- 3.1,
- 1.3)
- 51. 6 (
- 72.8,
- 30.4) Raizenne et al. ( 1989 ) Lake Erie, Ontario, Canada Campers without asthma
- 0.48 (
- 0.80,
- 0.16)
- 11.6 (
- 19.4,
- 3.8) Burnett et al. ( 1990 ) Lake Couchiching, Ontario, Canada Campers without asthma
- 0.32 (
- 1.8, 1.2)
- 7.6 (
- 42.1, 26.9) Higgins et al. ( 1990 ) San Bernardino, CA Campers without asthma
- 1.6 (
- 2.4,
- 0.87)
- 33.6 (
- 49.3,
- 17.9) Avol et al. ( 1991 ) Pine Springs, CA Campers without asthma
- 0.58 (
- 1.1,
- 0.12)
- 12.8 (
- 23.0,
- 2.6) Kinney et al. ( 1996 ) Pooled analysis Campers without asthma
- 0.90 (
- 1.2,
- 0.65)
- 20.0 (
- 25.5,
- 14.5) Berry et al. ( 1991 ) Hamilton, NJ Campers without asthma Data not available 32.8 (6.9, 58.7) PEF (ml/sec) Spektor et al. ( 1988a ) Lake Fairview, NJ Campers without asthma
- 1.8 (
- 3.3,
- 0.40)
- 80.0 (
- 142.7,
- 17.3) Raizenne et al. ( 1989 ) Lake Erie , Ontario, Canada Campers without asthma
- 0.07 (
- 0.56, 0.41)
- 4.0 (
- 30.7, 22.7) Burnett et al. ( 1990 ) Lake Couchiching, Ontario, Canada Campers without asthma
- 1.9 (
- 3.8,
- 0.05)
- 106.4 (
- 209.9,
- 2.9) Higgins et al. ( 1990 ) San Bernardino, CA Campers without asthma
- 0.87 (
- 2.1,
- 0.34)
- 44.0 (
- 105,
- 17.2) Avol et al. ( 1991 ) Pine Springs, CA Campers without asth ma 1.9 (0.71, 3.1) 86.8 (31.9, 142) Kinney et al. ( 1996 ) Pooled analysis Campers without asthma 0.31 (
- 0.88, 1.5) 6.8 (
- 19.1, 32.7) Berry et al. ( 1991 ) Hamilton, NJ Campers without asthma Data not available
- 40.4 (
- 132.1, 5 1.3) Neas et al. ( 1999 ) Philadelphia, PA Campers without asthma
- 0.58 (
- 1.5, 0. 33)
- 27.5 (
- 70.8, 15.8) Thurston et al. ( 1997 ) CT River Valley, CT Campers with asthma
- 2.8 (
- 4.9,
- 0.59)
- 146.7 (
- 261.7,
- 31.7)

a All effect estimates 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 (9:00 a.m.
- 9:00 p.m.) O 3 . As has been observed in controlled human exposure studies, FEV 1 and PEF responses to 

### 1 ambient O 3 exposure varied among individual campers. Based on separate regression 

### 2 analyses of data from individual subjects, O 3 exposure was associated with a wide range 

### 3 of changes in lung function across subjects ( Berry et al., 1991 ; Higgins et al., 1990 ; 

### 4 Spektor et al., 1988a ) . For example, in the study of children attending camp in Fairview 

### 5 Lake, NJ, 36% of subjects had statistically significant O 3 - associated decreases in FEV 1 , 

### 6 and the upper dec ile of response was a 6.3% decrease in FEV 1 per a 40

- pbb increase in 1

- 

### 7 h avg O 3 ( Spektor et al., 1988a )

. 

### 8 In contrast with these previous studies, a recent cross

- sectional study of children 

### 9 attending six different summer camps in Belgium did not find an association between 

### 10 ambient O 3 exposure and lung function. The ambient O 3 concentrations in this recent 

### 11 study was in the range of those in previous studies (Table 6

- 1); however, this recent study 

### 12Draft

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- 28 September 2011 differed from previous studies in that each subject was examined only on one day, and 

### 1 investigators performed between

- camp comparisons rather than withi n - subject 

### 2 comparisons. Camps with higher daily 1

- h max O 3 concentrations did not consistently 

### 3 have larger decreases in mean intraday FEV 1 or FEV 1 /FVC ( Nickmilder et al., 2007 )

. 

### 4
Populations Exercising Outdoors Similar to camp studies, studies of individuals exercising outdoors were noted for the 

### 5 serial examination of subjects over days with a wide range in ambient O 3 concentrations 

### 6 and onsite assessment of O 3 exposures during discrete periods of outdoor exercise. These 

### 7 studies collectively show that mean O 3 e xposures ranging from 40 to 66 ppb during 

### 8 exercise of variable duration and intensity are associated with small (< 1 to 4% per 

### 9 standardized increment in O 3 1 ) decreases in lung function in adults (Figure 6

- 4 and Table 

### 10 6

- 3). Similar observations were made in children exercising outdoors (Table 6

- 3). For 

### 11 both adults and children, evidence was provided largely by older studies that were 

### 12 reviewed in the 1996 and 2006 O 3 AQCDs. 

### 13

Figure 6 - 4 Percent change in FEV 1 

### in association with ambient ozone exposures of ad ults exercising outdoor s . Studies generally are organized in order of decreasing exercise duration. Effect estimates are from single - pollutant models and are standardized to a 40 - ppb increase for ozone exposures averaged over 15 minutes to 1 hour and a 3 0 - ppb increase for ozone exposures averaged over 3 to 8 hours.

1 Effect estimates were standardiz ed to a 40
- , 30
- , and 20
- ppb increase for 1
- h max, 8
- h max, and 24
- h avg O 3 . 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

- 5
- 4
- 3
- 2
- 1 0 1 2 Percent change in FEV 1 per standardized increment in O 3 (95% CI)Draft

– Do Not Cite or Quote 6
- 29 September 2011 

### Table 6 - 3 Additional characteristics and quantitative data for studies represented in Figure 6 - 4 and results from studies in children exercising outdoors Study Location Population Exercise dura tion O 3 Averaging Time Parameter Standardized percent change (95% CI) a Studies of adults Korrick et al. ( 1998 ) Mt. Washington, NH Adult day hikers 2
- 12 h Hike duration FEV 1 - 1.5 (
- 2.8,
- 0.24) Girardot et al. ( 2006 ) Great Smoky Mt, TN Adult day hikers 2
- 9 h Hike duration FEV 1 0.72 (
- 0.46, 1.90) Hoppe et al. ( 2003 ) Munich, Germany Adults exercising 2 h 30
- min max (1:00 p.m. - 4:00 p.m.) FEV 1 PEF - 1.3 (
- 2.6, 0.13)

- 2.8 (
- 5.9, 0.44) Selwyn et al. ( 1985 ) b Houston, TX Adults exercising NR 15
- min max FEV 1 - 16 ml (
- 31.1,
- 0.87) c Spektor et al. ( 1988a ) b Tuxedo, NY Adults exercising 15
- 55 min 30
- min avg FEV 1 - 1.31 (
- 2.0,
- 0.65) Brunekreef et al. ( 1994 ) Netherlands Adults exercising 10 min
- 1 h Exercise duration FEV 1 - 0.82 (
- 1.6,
- 0.02) Studies of children not included in Figure 6 - 4 Braun
- Fahrlander et al. ( 1994 ) Switzerland Children exercising 10 min 30
- min avg PEF
- 3.8 (
- 6.9,
- 0.96) Castillejos et al. ( 1995 ) Mexico City, Mexico Childre n exercising 15 min (2 periods) 1
- h avg FEV 1 - 0.48 (
- 0.72,
- 0.24)
Hoek et al. ( 1993 ) Wageningen, Netherlands Children exercising 1 h 1
- h avg PEF
- 2.2 (
- 4.9, 0.55) NR = Not reported.
a Effect estimates are standardized to a 40
- ppb increase for O 3 exposures averaged over 15 min to 1 h and a 30
- ppb increase for O 3 exposures averaged over 3 to 8 h.

b Results not included in the figure because data were not provided to calculate percent change in lung function.
c The 95% CI was constructed using a standard error that was estimated from the p
- value Two studies of adult day

- hikers of similar design and ambient O 3 concentrations 

### 1 produced contrasting results ( Girardot et al., 2006 ; Korrick et al., 1998 ) . These studies 

### 2 mostly comprised wh ite, healthy adults and examined changes in lung function associated 

### 3 with O 3 exposures during multihour (2

- 12 h) periods of outdoor exercise. Although 

### 4 analyses of day

- hikers were based on a one

- time assessment of lung function, they 

### 5 included much larger sa mple sizes compared with panel studies of individuals exercising 

### 6 outdoors. Among 530 hikers on Mt. Washington, NH, Korrick et al. ( 1998 ) reported 

### 7 posthike declines in FEV 1 and FVC of a pproximately 0.7

- 1.5% per a 30

- ppb increase in 

### 8 2

- to 12

- h avg O 3 . In contrast, among 354 hikers in Great Smoky Mountains National 

### 9 Park, TN, Girardot et al. ( 2006 ) more recently found that O 3 exposure was associated 

### 10 with posthike increases in many of the same lung function indices. Several differences in 

### 11 study characteristics were used by Girardot et al. ( 2006 ) to explain discrepant results, 

### 12 including their use of a larger number of less

- well trained technicians, shorter mean 

### 13 duration of hike (5 hours versus 8 hours), and older mea n age of their subjects. 

### 14 As was observed in camp studies, the magnitudes of O 3 - associated decreases in lung 

### 15 function varied among individual subjects. Korrick et al. ( 1998 ) found lar ger O 3 - 

### 16Draft

– Do Not Cite or Quote 6
- 30 September 2011 associated decreases in FEV 1 among hikers who were male, had history of asthma or 

### 1 wheeze, were never smokers, and hiked greater than 8 hours. Additionally, O 3 was 

### 2 associated with an increased odds of a greater than 10% decline in FEF 25

- 75% among 

### 3 hik ers (OR: 2.3 [95% CI: 1.2, 6.7] per 30

- ppb increase in 2

- to 12

- h avg O 3 ) ( Korrick et 

### 4 al., 1998 ) . Likewise, Hoppe et al. ( 2003 ) found that on days with 30

- min max (1:00 p.m.

- 

### 5 4:00 p.m.) ambient O 3 concentrations above 50 ppb, 14% of athletes had at least a 20% 

### 6 decrease in lung function or 10% increase in airway resistance. 

### 7

Outdoor Workers The 2006 O 3 AQC D indicated that ambient O 3 exposure was associated consistently with 

### 8 decrements in lung function among outdoor workers ( U.S. EPA, 2006b ) , and recent 

### 9 studies produced similar findings ( Thaller et al., 2008 ; Chan and Wu, 2005 ) (Figure 6

- 5 

### 10 and Table 6

- 4). Although most of these studies assessed O 3 exposures using central site 

### 11 measurements, they were noteworthy for the long periods o f time spent outdoors (6

- 14 

### 12 hours across studies). Further, associations between O 3 exposure and lung function 

### 13 decrements were found for time periods during which ambient O 3 concentrations did not 

### 14 exceed 80 ppb (Table 6

- 1) ( Chan and Wu, 2005 ; Brauer et al., 1996 ; Hoppe et al., 1995 )

. 

### 15 In particular, Many studies of outdoor workers found that in addition to same

- day 

### 16 exposures, O 3 exposures lagged 1 or 2 days ( Chan and Wu, 2005 ; Brauer et al., 1996 ) or 

### 17 exposures averaged over 2 days ( Romieu et al., 1998a ) were associated with equal or 

### 18 larger decrements in lung function (Figure 6

- 5 and Table 6

- 4). 

### 19 Similar to other populations with increased outdoor exposure, the magnitudes of O 3 - 

### 20 associated lung function decrements in outdoor workers were small. Per standard ized 

### 21 increment in O 3 concentration 1 , decreases in lung function ranged between less than 1% 

### 22 and 3.6%. The magnitude of decrease was not found to depend strongly on duration of 

### 23 outdoor work or ambient O 3 concentration. The largest decrease (6.4% per 40

- ppb 

### 24 increase in 1

- h max O 3 ) was observed among berry pickers in British Columbia who were 

### 25 exposed to relatively low ambient O 3 concentrations (work shift mean: 26.0 ppb [SD: 

### 26 11.8]) but had longer periods of outdoor work (8

- 14 hours) ( Brauer et al., 1996 ) (Figure 

### 27 6

- 5 and Table 6

- 4). However, a much smaller O 3 - associated decrease in FEV 1 was found 

### 28 among street workers in Mexico City who were exposed to higher O 3 concentrations 

### 29 (work shift mean: 67.3 ppb [SD: 24]) during a similar duration of outdoor work. Among 

### 30 studies of outdoor workers, the smallest magnitude of decrease (0.4% decrease (95% CI: 

### 31

- 0.8, 0) in afternoon FEV 1 /FVC per 40

- ppb increase in 1

- h max O 3 ) was observed among 

### 32 lif eguards in Galveston, TX ( Thaller et al., 2008 ) whose outdoor work periods were 

### 33 shorter than those of the berry pickers but who were exposed to a similar range of 

### 34

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
- 31 September 2011 

### Figure 6 - 5 Percent change in lung function in association with ambient ozone exposures among outdoor workers
. Studies generally are organized in order of increasing mean ambient ozone concentration. Effect estimates are from single - pollutant models and are standardized to a 40 - ppb increase for 30 - min or 1 - h max ozone exposures.

Table 6 - 4 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 Lifeguards FVC FEV 1 /FVC 6
- 8 h 1
- h max 0 0.24 (
- 0.28, 0.72)

- 0.40 (
- 0.80, 0) Brauer et al. ( 1996 ) British Columbia, Canada Berry pickers 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 Forestry workers FEV 1 NR 30
- min max (1:00 p.m. - 4:00 p.m.) 0
- 1.4 (
- 3.0, 0.16) Romieu et al. ( 1998a ) Mexico City, Mexico Male street workers FEV 1 Mean (SD): 9 h (1) 1
- h max 0 0
- 1 avg Placebo Antioxidant Placebo Antioxidant - 2.1 (
- 3.3,
- 0.85)

- 0.52 (
- 2.0, 0.97)

- 3.4 (
- 6.0,
- 0.78)

- 1.2 (
- 4.2, 1.8) Chan et al. ( 2005 ) b Taichung City, Taiwan Mail carriers PEF 8 h 8
- h avg (9:00 a.m.
- 5:00 p.m.) 0 1 - 1.0 (
- 1.3,
- 0.66)

- 1.1 (
- 1.5,
- 0.78) NR = Not reported.
a Effect estimates are standardized to a 40
- ppb increase for 30
- min or 1
- h max O 3 and a 30
- ppb increase for 8
- h max O 3 . a PEF results not included in figure. Study Thaller et al. (2008)

Brauer et al. (1996)

Hoppe et al. (1995) Romieu et al. (1998) Population Lifeguards

Berry pickers

Forestry workers
Street workers 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 standardized increment in O 3 (95% CI)Draft

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- 32 September 2011 ambient O 3 concentrations. Few studies provided information on ventilation rate or pulse 

### 1 rate, thus it was difficult to ascertain whether differences in the magnitudes of O 3 - 

### 2 associated decreases in lung function were related to differences in workers ’ levels of 

### 3 exertion. 

### 4

Associations at lower ozone concentrations Studies of populations engaged in outdoor activity examined and found that associations 

### 5 between O 3 and lung function decrements persisted at lower O 3 concentr ations 

### 6 (Table 6

- 5). Among adults exercising outdoors, Spektor et al. ( 1 988b ) found that 

### 7 associations persisted in analyses restricted to 30

- min max ambient O 3 concentrations 

### 8 less than 80 ppb, and for most lung function parameters, effect estimates were similar to 

### 9 those obtained for the full range of O 3 concentrations (Tabl e 6

- 5). In a study of children 

### 10 attending summer camp, similar effects were estimated for the full range of 1

- h avg O 3 

### 11 concentrations and those less than 60 ppb ( Spektor et al., 1988a ) . Brunekreef et al. ( 1994 ) 

### 12 found ambient O 3 exposure (10

- min to 1

- h) during outdoor exercise to be associated with 

### 13 decreases in lung function in analyses restricted to concentrations less than 61 (Table 6

- 5) 

### 14 and 51 ppb. However, effect estimates we re near zero with O 3 concentrations less than 

### 15 41 ppb ( Brunekreef et al., 1994 ) . In contrast, B rauer et al. ( 1996 ) found associations 

### 16 persisted with 1

- h max O 3 concentrations less than 40 ppb. 

### 17

Table 6 - 5 Associations between ambient ozone exposure and lung function de crements in different ranges of ambient ozone concentrations Study Location Population Parameter O 3 Averaging Time O 3 Concentration Range Standardized percent change (95% CI) a Brunekreef et al. ( 1994 ) Netherlands Adults exercising % change FEV 1 10
- m to 1
- h Lag 0 Full range O 3 < 61 ppb - 0.82 (
- 1.6,
- 0.02)

- 2.1 (
- 4.5, 0.32) Spektor et al. ( 1988b ) Tuxedo, NY Adults exercising FEV 1 (ml) 30
- min avg Lag 0 Full range O 3 < 80 ppb - 54 (
- 84,
- 27) b

- 52 (
- 101,
- 3.4) b Spektor et al. ( 1988a ) Fairview Lake, NJ Campers without asthma % change FEV 1 1
- h avg Lag 0 Full range O 3 < 80 ppb O 3 < 60 ppb - 2.7 (
- 3.3,
- 2.0)

- 1.4 (
- 2.5,
- 0.34)

- 2.2 (
- 3.7,
- 0.80) Korrick et al. ( 1998 ) Mt. Washi ngton, NH Adult day hikers % change FEV 1 Hike duration (2
- 12 h) Lag 0 Full range O 3 > 40 ppb - 1.5 (
- 2.8,
- 0.24)

- 2.6 (
- 4.9,
- 0.32)

a Effect estimates are standardized to a 40
- ppb increase for O 3 exposures averaged over 10 min to 1 h and a 30
- ppb increase for O 3 exposures averaged over 2 to12 h.

b Data were not provided to calculate percent change.
Korrick et al. ( 1998 ) ex amined associations with hike

- time average O 3 exposures (2

- 12 h) 

### 18 and found effect estimates that were more negative in analyses restricted to O 3 

### 19 concentrations greater than 40 ppb. Based on the results from a nonparametric model in 

### 20Draft

– Do Not Cite or Quote 6
- 33 September 2011 Korrick et al. ( 1998 ) , it appeared that the association between O 3 exposure and lung 

### 1 function decrements in this population was limited to 2

- to 12

- h avg O 3 exposures above 

### 2 40 ppb. 

### 3

Children with Asthma Assoc iations between ambient O 3 exposures and lung function decrements in children 

### 4 with asthma have been examined in epidemiologic studies conducted across diverse 

### 5 geographical locations and a range of ambient O 3 concentrations (Table 6

- 6). Whereas 

### 6 studies of p opulations with increased outdoor exposures monitored O 3 exposures at the 

### 7 site of subjects ’ outdoor activities and used trained staff to measure lung function, studies 

### 8 of children with asthma relied more heavily on O 3 measured at central monitoring sites 

### 9 a nd lung function measured by subjects. However, studies of children with asthma have 

### 10 provided more information on factors that may confer increased susceptibility to the 

### 11 respiratory effects of O 3 exposure, confounding by copollutant exposure or meteorology , 

### 12 and the potential clinical significance of O 3 - associated changes in lung function with the 

### 13 concurrent assessment of respiratory symptoms. 

### 14 Collectively, the large body of evidence, which includes large U.S. multicity studies and 

### 15 several smaller studies co nducted in the U.S., Mexico City, and Europe, demonstrates 

### 16 that increases in ambient O 3 exposure (various averaging times and lags) are associated 

### 17 with decrements in FEV 1 (Figure 6

- 6 and Table 6

- 7) and PEF (Figure 6

- 7 and Table 6

- 8) 

### 18 in children with asthma. In addition to examining a single lung function measurement per 

### 19 day, several studies examined associations of O 3 exposure with measures of lung function 

### 20 variability. Al though different definitions of variability were used, studies consistently 

### 21 found that O 3 - associated changes in lung function variability were indicative of poorer 

### 22 lung function, whether characterized as a decrease from the individual ’ s mean lung 

### 23 function over the study period ( Jalaludin et al., 2000 ) , a decrease in lung function over 

### 24 the course of the day ( Lewis et al., 2005 ) , or a decrease in the lowest daily measurement 

### 25 ( Just et al., 2002 )

. 

### 26 Studies of children with asthma that were restricted to winter months provided little 

### 27 evidence of an association between various single

- and multi

- day lags of ambient O 3 

### 28 exposure and changes in lung function; several studies reported O 3 - associated increases 

### 29 in lung function ( Dales et al., 2009 ; Liu et al., 2009a ; Rabinovitch et al., 2004 ) . In colder 

### 30 months, ambient O 3 concentrations are low and in many locations, children remain 

### 31 primarily indoors. Thus, it is less likely that effects will be demonstrated for O 3 . As noted 

### 32 in previous AQCDs for lung function and other endpoints such as respiratory hospital 

### 33 admissions, ED visits, and mortality, associations with O 3 generally are greater in the 

### 34 warm season. 

### 35Draft

– Do Not Cite or Quote 6
- 34 September 2011 

### Table 6 - 6 Mean and upper percentile concentrations of ozone in epidemiologic studies examining lung function in children with asthma
Study Location Years/Season O 3 Averging Time Mean/Median Concentration (ppb) Upper Percentile Concentrations (ppb) Mortimer et al. ( 2002 ) Mortimer et al. ( 2000 ) Bronx, East Harlem, NY; Baltimore, MD; Washington, DC; Detroit, MI, Cleveland, OH; Chicago,IL; St. Louis, MO (NCICAS) 1993 Warm season 8
- h avg (10:00a.m.
- 6:00 p.m.) 48 NR

O ’ Connor et al. ( 2008 ) Boston, MA; Br onx, Manhattan NY; Chicago, IL; Dallas, TX, Seattle, WA; Tucson, AZ (ICAS) 1998
- 2001 All
- year 24
- h avg NR NR

Thurston et al. ( 1997 ) Connecticu t River Valley, CT 1991
- 1993 Warm season 1
- h max 83.6 a Max: 160
Lewis et al. ( 2005 ) Detroit, MI 2001
- 2002 All
- year 8
- h max Eastside: 40.4 a Westside: 41.4 a Overall max: 92.0 a
Rabinovitch et al. ( 2004 ) Denver, CO 1999
- 2002 Cold season 1
- h max 28.2 Max 70.0 Delfino et al. ( 2004 ) Alpine, CA September
October 1999 April
- June 2000 8
- h max 62.9 90th: 83.9, Max: 105.9

Dales et al. ( 2009 ) Liu et al. ( 2009a ) Windsor, ON, Canada 2005 Cold season 24
- h avg 1
- h max 14.1 27.2 75th: 17.8 75th: 32.8 Romieu et al. ( 1996 ) N orthern Mexico City, Mexico April
- July 1991 November 1991
- February 1992 1
- h max 190 Max: 370

Romieu et al. ( 1997 ) S out hern Mexico City, Mexico April
- July 1991 November 1991
- February 1992 1
- h max 196 Max: 390

Romieu et al. ( 2002 ) ; Romieu et al. ( 2004a ) ; Romieu et al. ( 2006 ) Mexico Ci ty, Mexico 1998
- 2000 All
- year 8
- h max 1
- h max 69 102 Max: 184 Max: 309 Barraza
- Villarreal et al. ( 2008 ) ; Romieu et al. ( 2009 ) Mexico City, Mexico 2003
- 2005 All
- year 8
- h m ax 1
- h max 31.6 86.5 Max (8
- h): 86.3

Hernández
- Cadena et al. ( 2009 ) Mexico City, Mexic o 2005 Warm season 24
- h avg 1
- h max 26.3 74.5 75th: 35.3; Max: 62.8 75th: 92.5; Max: 165.0 Gielen et al. ( 1997 ) Amsterdam, Netherlands 1995 Warm season 8
- h max 34.2 Max: 56.5
Just et al. ( 2002 ) Paris, France April
- June 1996 24
- h avg 30.0 Max: 61.7 Hoppe et al. ( 2003 ) Munich, Germany 1992
- 1995 Warm season 30
- min max (1:00 p.m.
- 4:00 p.m.) High O 3 days: 66.9 Control O 3 days: 32.5 Max: 91 (high O 3 days) 39 (control O 3 days) Wiwatanadate and Trakultivakorn ( 2010 ) Chiang Mai, Thailand August 2005
- June 2006 24
- h avg 17.5 90th: 26.82 Max: 34.65 Jalaludin et al. ( 2000 ) Sydney, Australia February
December 1994 15
- h avg (6:00 a.m. - 9:00 p.m.) 12 Max: 43 NCICAS = National Cooperative Inner
- City Asthma Study, NR = Not Reported, ICAS = Inner City Asthma Study, Max = Maximum. a Measured at sites established by investigators.Draft

– Do Not Cite or Quote 6
- 35 September 2011 

### Figure 6 - 6 Percent change in FEV 1 

### in association with ambient ozone exposures among children with asthma. Results generally are presented in order of increasing mean ambient ozone concentration. CS = Corticosteroid, URI = Upper respiratory infection. Effect estimates are from single - poll utant models and are standardized to a 40 - ppb increase for 30 - min or 1 - h max ozone exposures, a 30 - ppb increase for 8 - h max or 8 - h avg ozone exposures, and a 20 - ppb increase for 24 - h avg ozone exposures. 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 2

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 Ile/Val GSTP1 Val/Val , moderate/severe asthma

, moderate/severe asthma ◄ ◄

- 10
- 8
- 6
- 4
- 2 0 2 4 Percent change in FEV 1 per standardized increment in O 3 (95% CI)Draft

– Do Not Cite or Quote 6
- 36 September 2011 

### Table 6 - 7 Additional characteristics and quantitativ e data for studies represented in Figure 6 - 6
Study Location/ Population O 3 Averaging

Time O 3 Lag Parameter Subgroup Standardized percent change (95% CI) a Liu et al. ( 2009a ) Windsor, ON, Canada Children with ast hma 24
- h avg 0 FEV 1 - 0.89 (
- 3.5, 1.8)
Lewis et al. ( 2005 ) Detroit, MI Children with asthma 8
- h max 2 Lowest daily FEV 1 CS user With URI - 8.0 (
- 13.5,
- 2.1)

- 5.4 (
- 11.3, 1.0) Hoppe et al. ( 2003 ) Munich, Germany Children 30
- min m ax (1:00p.m.
- 4:00p.m.) 1 Afternoon FEV 1 Afternoon FVC Without asthma With asthma Without asthma With asthma 0.93 (
- 0.80, 2.7)

- 0.56 (
- 4.6, 3.7)

- 0.09 (
- 1.7, 1.6)

- 3.5 (
- 5.9,
- 1.0) Barraza
- Villarreal et al. ( 2008 ) Mexico City, Mexico Children 8
- h max 0
- 4 avg FEV 1 Without asthma With asthma - 1.5 (
- 4.7, 1.7) b

- 0.12 (
- 2.0, 1.8) b Romieu et al. ( 2002 ) Mexico City, Mexico Children with asthma 1
- h max 1 FEV 1 Placebo Antioxida nt Placebo,moderate/severe asthma Antioxidant, moderate/severe asthma - 0.21 (
- 0.78, 0.36) b 0.05 (
- 0.59, 0.69) b

- 1.1 (
- 2.0,
- 0.19) b

- 0.04 (
- 0.92, 0.83) b

Romieu et al. ( 2006 ) Mexico City, Mexico Children with asthma 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 Children with asthma 1
- h max 0 Evening % predicted FEV 1 - 0.47 (
- 1.9, 0.95)
Rabinovitch et al. ( 2004 ) Denver, CO Children with asthma 1
- h max 0
- 2 avg Morning FEV 1 (ml) 53 (
- 2.4, 108)
O ’ Connor et al. ( 2008 ) 7 U.S. communities Children with asthma 24
- h avg 1
- 5 avg Change in % predicted FEV 1 - 0.41 (
- 1.0, 0.21) CS = corticosteroid, URI = Upper respiratory infection.
a Effect e stimates are standardized to a 40
- ppb increase for 30
- min 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 .

c 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 lung function.Draft

– Do Not Cite or Quote 6
- 37 September 2011 

### Figure 6 - 7 Percent change in PEF or FEF 25 - 75% 

### in association with ambient ozone exposures among children with asthma. Results generally are presented in order of increasing mean ambient ozone 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 ozone exposures and a 3 0 - ppb increase for 8 - h max or 8 - h avg ozone exposures. Study Gielen et al. (1997) Mortimer et al. (2002) Mortimer et al. (2000)

Thurston et al. (1997) Romieu et al. (2004)

Romieu et al. (1996)

Romieu et al. (1997) Parameter
PEF
PEF PEF

PEF
FEF 25
- 75%

Evening PEF

Evening PEF O 3 Lag
2
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 lung function parameter per standardized increment in O 3 (95% CI)Draft

– Do Not Cite or Quote 6
- 38 September 2011 

### Table 6 - 8 Additional characteristics and quantitative data for studies represented in Figure 6 - 7 Study Location/ Population O 3 Averaging Time O 3 Lag Parameter Subgroup Standardized percent change (95% CI) a Gielen et al. ( 1997 ) Amsterdam, Netherlands Children w/ asthma 8
- h max 2 PEF
- 1.3 (
- 2.6,
- 0.10)
Mortimer et al. ( 2002 ) 8 U.S. communities Children w/ asthma 8
- h avg (10:00a.m.
- 6:00p.m.) 1
- 5 avg PEF All subjects
- 1.2 (
- 2.1,
- 0.26)

Mortimer et al. ( 2000 ) 8 U.S. communities Children w/ asthm a 8
- h avg (10:00a.m.
- 6:00p.m.) 1
- 5 avg PEF Normal BW Low BW 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 Children w/ asthma 1
- h avg 0 Intraday change PEF - 2.8 (
- 4.9,
- 0.59)
Romieu et al. ( 2004a ) Mexico City, Mexico Children w/ asthma 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 Children w/ asthma 1
- h max 0 2 Evening PEF
- 0.17 (
- 0.79, 0.46)

- 0.55 (
- 1.3, 0.19) Romieu et al. ( 1997 ) S outhern Mexico City, Mexico Chil dren w/ asthma 1
- h max 0 2 Evening PEF
- 0.52 (
- 1.0,
- 0.007)

- 0.06 (
- 0.70, 0.58) Studies not included in Figure 6 - 7 b Jalaludin et al. ( 2000 ) Sydney, Australia Children w/ asthma 24
- h avg 0 % variability PEF Wheeze, no asthma Asthma, no AHR Asthma, with AHR 3.8 (0.25, 7.38) c

- 0.71 (
- 2.6, 1.2) c

- 5.2 (
- 8.3,
- 2.2) c Wiwatanadate and Trakultivakorn ( 2010 ) Chiang Mai, Thailand Children w/ asthma 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 ) 7 U.S. communities Chi ldren w/ asthma 24
- h avg 1
- 5 avg Change in % predicted PEF - 0.22 (
- 0.86, 0.43) 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 or 8
- h 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 examined or because sufficient data were not provided to calculate percent change in lung function.

c Outcome defined as the percent deviation from individual mean PEF during the study period. Group
- stratified effect estimates 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 ; 

### 2 Mortimer et al., 2000 ) a nd Inner

- City Asthma Study (ICAS) ( O'Connor et al., 2008 )

. 

### 3 Although the two studies differed in the cities, seasons, racial distribution of subjects, and 

### 4 lung function indices examined, results were fairly similar. In ICAS, which included 

### 5 children with asthma and atopy (i.e., allergic sensitization) and year

- rou nd examinations 

### 6 of lung function, a 20

- ppb increase in the lag 1

- 5 average of 24

- h avg O 3 was associated 

### 7 with a 0.41

- point decrease in percent predicted FEV 1 (95% CI:

- 1.0, 0.21) and a 0.22

- 

### 8 point decrease in percent predicted PEF (95% CI:

- 0.86, 0.43). 

### 9Draft

– Do Not Cite or Quote 6
- 39 September 2011 Lag 1

- 5 avg O 3 (8

- h avg, 10:00 a.m.

- 6:00 p.m.) also was associated with declines in PEF 

### 1 in NCICAS, which included different U.S. cities, summer

- only measurements, larger 

### 2 proportions of Black and Hispanic children, and fewer subjects with atopy (79%) 

### 3 ( Mortimer et al., 2002 ) . NCICAS additionally identified groups potentially at increased 

### 4 risk of O 3 - associated decrements in PEF. Lar ger effects were estimated in males, children 

### 5 of Hispanic ethnicity, children living in crowded housing, and as indicated in Figure 6

- 7 

### 6 and Table 6

- 8, children with low birth weight ( Mortimer et al., 2000 ) . Somewhat 

### 7 paradoxically, O 3 was associated with a larger decrease in PEF among subjects taking 

### 8 cromolyn, medication typically used to treat asthma due to allergy, but a smaller decrease 

### 9 among subjects with positive atopy (as determined by skin prick test). Similar to 

### 10 observations from studies of populations with increased outdoor exposures, Mortimer et 

### 11 al. ( 2002 ) found that associations persisted at lower ambient O 3 concentrations. At 

### 12 concentrations below 80 ppb, a 30

- ppb increase in lag 1

- 5 of 8

- h avg O 3 was associated 

### 13
w ith a 1.4% decrease (95% CI:

- 2.6,

- 0.21) in PEF, which was similar to the effect 

### 14 estimated for the full range of O 3 concentrations (Figure 6

- 7 and Table 6

- 8). In a study of 

### 15 children with asthma in the Netherlands, Gielen et al. ( 1997 ) estimated similar effects for 

### 16 the full range of 8

- h max O 3 concentrations and concentrations below 51 ppb. 

### 17 The results from studies of children with asthma indicated that factors in addition to 

### 18 asthma influenced associations between ambient O 3 exposure and changes in lung 

### 19 function. In comparisons between children with and without asthma, Hoppe et al. ( 2003 ) 

### 20 and Jalaludin et al. ( 2000 ) generally found larger O 3 - associated lung function decrements 

### 21 in children with asthma; whereas Raizenne et al. ( 1987 ) did not consistently demonstrate 

### 22 differences between campers with and without asthma. In their study of children in 

### 23 Mexico City, Barraza

- Villarreal et al. ( 2008 ) estimated larger O 3 - associated decreases in 

### 24 children without asthma; however, 72% of these children had atopy. These findings 

### 25 indicated that in addition to asthma, atopy, a condition also characterized by airway 

### 26 inflammation and simil ar respiratory symptoms, may increase the risk for O 3 - associated 

### 27 respiratory effects. 

### 28 As indicated in Figures 6

- 6 and 6

- 7 and Tables 6

- 7 and 6

- 8, in most studies of children 

### 29 with asthma, standardized increments in ambient O 3 exposure 1 were associated with 

### 30 decreases in lung function that ranged from less than 1% to 2%. Larger magnitudes of 

### 31 decreases (3

- 8% per standardized increments in O 3 ) were found in children with asthma 

### 32 who also were using CS, had a concurrent upper respiratory infection (URI), were 

### 33 GST M1 null, had low birth weight, or had increased outdoor exposure ( Romieu et al., 

### 34 2006 ; Lewis et al., 2005 ; Romieu et al., 2004a ; Jalaludin et al., 2000 ) than among 

### 35 children with asthma overall ( Barraza

- Villa rreal et al., 2008 ; Lewis et al., 2005 ; Delfino 

### 36

1 Effect estimates were standardized to a 40
- , 30
- , and 20
- ppb increas e for 1
- h max, 8
- h max, and 24
- h avg O 3 .Draft

– Do Not Cite or Quote 6
- 40 September 2011 et al., 2004 ; Romieu et al., 2002 ) . For example, Jalaludin et al. ( 2000 ) estimated a

- 5.2% 

### 1 deviation from mean FEV 1 per a 20

- ppb increase in 24

- h avg O 3 among children with 

### 2 asthma and airway hyperresponsiveness and a much smaller

- 0.71% deviation among 

### 3 children with asthma without airway hyperresponsiveness. In a group of 86 children with 

### 4 asthma in Detroit, MI , Lewis et al. ( 2005 ) also reported that associations between O 3 

### 5 exposure and lung function decrements were confined largely to children with asthma 

### 6 who used CS or had a concurrent URI. These two groups were observed to have the 

### 7 largest O 3 - associated decrements in lung functio n among all studies of children with 

### 8 asthma. A 30

- ppb increase in 8

- h max ambient O 3 exposure was associated with a 8.0% 

### 9 decrease in the mean of lowest daily FEV 1 among CS users and a 5.4% decrease among 

### 10 subjects reporting concurrent URI ( Lewis et al., 2005 ) (Figure 6

- 6 and Table 6

- 7). 

### 11 Hete rogeneity in lung function responses to ambient O 3 exposure also has been 

### 12 demonstrated as inter

- individual variability in the magnitude of O 3 - associated changes in 

### 13 lung function. Mortimer et al. ( 2002 ) found that for a 30

- ppb increase in lag 1

- 5 avg of 8

- 

### 14 h avg O 3 , there was a 30% (95% CI: 4, 61) increase in the incidence of a greater than 

### 15 10% decline in PEF. Likewise, Hoppe et al. ( 2003 ) found that while the percentages of 

### 16 change in individual lung function parameters were variable and small, 47% of children 

### 17 with asthma in their study experienced greater than 10% decline in FE V 1 , FVC, or PEF 

### 18 or 20% increase in airway resistance on days with 30

- min (1:00 p.m.

- 4:00 p.m.) max 

### 19 ambient O 3 concentrations greater than 50 ppb relative to days with less than 40 ppb O 3 . 

### 20 In addition to finding groups of children with asthma with increased sensitivity to O 3 

### 21 exposure, epidemiologic studies have indicated that the decreases in lung function 

### 22 observed in association with increases in ambient O 3 exposure may be clinically 

### 23 significant by finding that the same or similar lag of O 3 exposure was ass ociated with 

### 24 decrements in lung function and increases in concurrently assessed respiratory symptoms 

### 25 ( Just et al., 2002 ; Mortimer et al., 2002 ; Gielen et al., 1997 ; Romieu et al., 1997 ; 

### 26 Thurston et al., 1997 ; Romieu et al., 1996 ) (see Figure 6

- 12 and Table 6

- 19 for symptom 

### 27 results). 

### 28 Effect modification by corticosteroid use In controlled human exposure studies, CS treatment of subjects with asthma generally has 

### 29 not prevented O 3 - induced FEV 1 decrements (Section 6.2.1.1). In epidemiologic studies 

### 30 reviewed in the 2006 O 3 AQCD, evidence was equivocal, as use of inhaled CS showed 

### 31 both protective ( Delfino et al., 2002 ; Mortimer et al., 2000 ) and exacerbating ( Gent et al., 

### 32 2003 ) effects on respiratory endpoints. Among recent studies, evidence for effect 

### 33 modification of lung function responses by CS use also was mixed. In Lewis et al. 

### 34 ( 2005 ) , analyses of interactions between O 3 exposure and CS use indicated stronger 

### 35 associations among CS users than among CS nonusers (quantitative results not reported 

### 36Draft

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- 41 September 2011 for CS nonusers). Among the 11 (12.8%) CS users, a 30

- ppb increase in lag 2 of 8

- h max 

### 1 O 3 was associated with an 8.0% decrease (95% CI:

- 13.5,

- 2.1) in lowest daily FEV 1 and 

### 2 a 6.7% increase (95% CI: 0.60, 13.2) in diurnal FEV 1 variability (indicating a decrease 

### 3 from morning to evening). Other lags (1 or 3

- 5 avg) or averaging times (24

- h avg) of 

### 4 exposure were estimated to have less impact. In contrast to Lewis et al. ( 2005 ) , 

### 5 Hernández

- Cadena et al. ( 2009 ) observed greater O 3 - related decrements in FEV 1 among 

### 6 the 60 CS nonusers than among the 25 CS users. In two winter

- only studies, 

### 7 consideration of CS use did not largely influence associations between ambient O 3 and 

### 8 lung function parameters ( Liu et al., 2009a ; Rabinovitch et al., 2004 )

. 

### 9 Although studies varied in populations and season examined, the incon sistency in effect 

### 10 modification by CS use may be explained, at least in part, by differences in the severity 

### 11 of asthma among CS users and the definition of CS use. Hernández

- Cadena et al. ( 2009 ) 

### 12 did not define CS use; however, the group of CS nonusers included both children with 

### 13 intermittent and persistent asthma. In Lewis et al. ( 2005 ) , most children with moderate to 

### 14 severe asthma (91%) were incl uded in the group of CS users (use for at least 50% of 

### 15 study days); however, these subjects had a higher percent predicted FEV 1 . Liu et al. 

### 16 ( 2009a ) did not provide information on asthma severity; however, they defined CS use 

### 17 more stringently as daily use. Differences in asthma severity and definition of CS use 

### 18 may explain why both CS use and nonuse could serve as indicators of severe or 

### 19 uncontrolled asthma across studies. Additionally, investigators did not assess adherence 

### 20 to reported CS regimen, and misclassification of CS use may bias findings. 

### 21 Effect modification by antioxidant capacity Ozone is a powerful oxidant whose secondary oxidation product s are recognized to 

### 22 initiate the key modes of action, including the activation of neural reflexes that mediate 

### 23 decreases in lung function (Section 5.3.2). Additionally, O 3 exposure of humans and 

### 24 animals induces changes in the levels of antioxidants in the ELF (Section 5.3.3). These 

### 25 observations support the biological plausibility for diminished antioxidant capacity 

### 26 increasing the risk of O 3 - associated respiratory effects and augmented antioxidant 

### 27 capacity decreasing risk. Controlled human exposure studies h ave demonstrated 

### 28 protective effects of α

- tocopherol (vitamin E) and ascorbate (vitamin C) supplementation 

### 29 on O 3 - induced lung function decrements (Section 6.2.1.1), and epidemiologic studies of 

### 30 children with asthma conducted in Mexico City have had similar findings. Particularly 

### 31 among children with moderate to severe asthma, ambient O 3 exposure was associated 

### 32 with a smaller decrease in FEV 1 in the group supplemented with vitamin C and E as 

### 33 compared with the placebo group ( Romieu et al., 2002 ) (Figure 6

- 6 and Table 6

- 7). 

### 34 Similarly, Romieu et al. ( 2009 ) observed protective effect for diets high in vitamins C 

### 35 and E as well as omega

- 3 fatty acids. Subjects were assigned to a fruits and vegetables 

### 36Draft

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- 42 September 2011 index (FVI) that characterized consumption of vitamins C and E and a Mediterranean die t 

### 1 index (MDI) that additionally represented the intake of omega

- 3 fatty acids, which have 

### 2 anti

- inflammatory effects. At lag 0

- 4 avg of 8

- h max O 3 concentrations ≥ 38 ppb, a 1

- unit 

### 3 increase in FVI was associated with a 137 ml (95% CI: 8, 266) increase in FE V 1 . This 

### 4 protective effect of FVI was diminished at O 3 concentrations ≤ 25 ppb (65 ml [95% CI:

- 

### 5 70, 200] increase in FEV 1 per 1

- unit increase in FVI). Similar results were obtained for 

### 6 MDI. 

### 7 Antioxidant capacity also can be characterized by variants in gen es encoding xenobiotic 

### 8 metabolizing enzymes with different enzymatic activities. Ambient O 3 exposure has been 

### 9 associated with greater decreases in lung function among children with asthma with the 

### 10 GSTM1 null genotype, which is associated with lack of oxida nt metaboilizing activity 

### 11 ( Romieu et al., 2004a ) . The difference in response between GSTM1 null and positive 

### 12 subjects was minimal in children supplemented with antioxidant vitamins (Fi gure 6

- 7 and 

### 13 Table 6

- 8). Although these findings are biologically plausible given the well



### 14 characterized evidence for O 3 effects mediated by secondary oxidation products, it is 

### 15 important to note that a larger body of controlled human exposure studies has n ot 

### 16 consistently found larger O 3 - induced lung function decrements in GSTM1 null subjects 

### 17 (Section 6.2.1.1). Effect modification by the GSTP1 variant is less clear. Romieu et al. 

### 18 ( 2006 ) observed larger O 3 - associat ed decreases in FEV 1 in children with asthma with the 

### 19 GSTP1 Ile/Ile or Ile/Val variant, both of which are associated with normal oxidative 

### 20 metabolism activity (Figure 6

- 6 and Table 6

- 7). Also unexpectedly, O 3 exposure was 

### 21 associated with an increase in FEV 1 among children with the GSTP1 Val/Val variant, 

### 22 which is associated with reduced oxidative metabolism. Rather than reflecting effect 

### 23 modification by the GSTP1 variant, these results may reflect effect modification by 

### 24 asthma severity, as 77% of subjects wi th the GSTP1 Ile/Ile genotype had moderate to 

### 25 severe asthma. Supporting evidence is provided by an earlier analysis of the same cohort, 

### 26 in which the effect of antioxidant supplementation was demonstrated more strongly in the 

### 27 smaller group of children with moderate to severe asthma than among all subjects with 

### 28 asthma ( Romieu et al., 2002 )

. 

### 29
Adults with Respiratory Disease Relative to studies in children with asthma, studies of adults with asthma or COPD have 

### 30 been limited in number. Characteristics and ambient O 3 concentration data from these 

### 31 studies are presented in Table 6

- 9. Studies that included both children and adults with 

### 32 ast hma did not consistently demonstrate associations between ambient O 3 exposure and 

### 33 decrements in lung function ( Ross et al., 2002 ; Delfino et al., 1997 ) . Ross et al. ( 2002 ) 

### 34 found that a 20

- ppb increase in lag 0 of 24

- h avg O 3 was associated with a 2.6 L/min 

### 35 decrease (95% CI:

- 4.3 , - 0.90) in evening PEF among subjects ages 5

- 49 years. This 

### 36Draft

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- 43 September 2011 decrement may have been indicative of a clinically significant effect, as lag 0 O 3 

### 1 exposure also was associated with an increase in symptom score. In another panel study, 

### 2 neither ambient nor pers onal O 3 12

- h avg exposure was reported to be associated with a 

### 3 decrease in lung function among subjects ages 9

- 46 years ( Delfino et al., 1997 )

. 

### 4 Comparisons o f adults with and without asthma did not conclusively demonstrate that 

### 5 adults with asthma were at increased risk of O 3 - associated respiratory effects. In the 

### 6 recent panel study of 16

- to 27

- year - old lifeguards in Galveston, TX, a larger O 3 - 

### 7 associated decre ment in FEV 1 /FVC was found among the 16 lifeguards with asthma (

- 

### 8 1.6% [95% CI:

- 2.8,

- 0.4] per 40 ppb increase in 1

- h max O 3 ) than among the 126 

### 9 lifeguards without asthma (

- 0.40% [95% CI:

- 0.80, 0] per 40 ppb increase in 1

- h max O 3 ) 

### 10 ( Brooks, 2010 ) . In the studies of day

- hikers, Korrick et al. ( 1998 ) found that the O 3 - 

### 11 associated lung function decrements observed among all hikers were driven by 

### 12 associations observed in hikers with history of asthma or wheeze (

- 4.4% [95% CI:

- 7.5,

- 

### 13 1.2] in FEV 1 per 30

- ppb increase i n 2

- 9 hr avg O 3 ). In contrast, Girardot et al. ( 2006 ) did 

### 14 not find ambient O 3 exposure to be consistently associated with decrements in lung 

### 15 function in subjects with o r without respiratory disease history. In another cross

- sectional 

### 16 study of 38 adults with asthma and 13 adults without asthma, atopy was observed to be a 

### 17 stronger susceptibility factor than was asthma ( Khatri et al., 2009 ) . Investigators reported 

### 18 a larger decrease in percent predicted FEV 1 /FVC per 30

- ppb increase in lag 2 of 8

- h max 

### 19 O 3 among the 38 subjects with atopy (with or w ithout asthma) (

- 12 points [95% CI:

- 21,

- 

### 20 3]) than among subjects with asthma (

- 4.7 points [95% CI:

- 11, 2.3]). Additionally, 

### 21 among adults with asthma, O 3 was associated with an increase in FEV 1 . Based on 

### 22 correlations observed between decreases in lung fun ction and decreases in quality of life 

### 23 scores, investigators inferred the O 3 - associated decreases in lung function to be clinically 

### 24 significant. They suggested that atopy may influence responses to ambient O 3 exposure 

### 25 because during the summer, high ambien t O 3 concentrations may increase the 

### 26 allergenicity of pollens. 

### 27 O 3 was not found to have a strong effect on the lung function of adults with asthma in 

### 28 panel studies conducted in Europe and Asia during low ambient O 3 periods 

### 29 ( Wiwatanadate and Liwsrisakun, 2011 ; Lag orio et al., 2006 ; Park et al., 2005a ) , including 

### 30 one study conducted in Korea during a period of dust storms ( Park et al., 2005a ) . In these 

### 31 studies that examined multiple lags of O 3 exposure , O 3 generally was associated with 

### 32 increases in lung function. 

### 33 Controlled human exposure studies demonstrate robust O 3 - induced spirometric responses 

### 34 in children and young adults but diminished, statistically nonsignificant responses in 

### 35 older adults, both healthy and with COPD (Section 6.2.1.1). Similarly, in a recent 

### 36 epidemiologic study that followed 94 adults with COPD ( ages 40

- 83 years) daily over a 

### 37Draft

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- 44 September 2011 2

- year period, an increase in ambient O 3 exposure was not associated consistently with 

### 1 decreases PEF, FEV 1 , and FVC ( Pe acock et al., 2011 ) . For example, in an analysis 

### 2 restricted to the summer of 1996, a 30

- ppb increase in 8

- h max O 3 was associated with a 

### 3 1.7 L/min decrease (95% CI:

- 3.1,

- 0.39) in PEF. However, during the summer of 1997, 

### 4 O 3 was found to have little eff ect on PEF (

- 0.21 L/min [95% CI:

- 2.4, 2.0] per 30

- ppb 

### 5 increase in 8

- h max O 3 ). Further, in this study, an increase in ambient O 3 exposure was 

### 6 associated with a lower odds of a large PEF decrement (OR for a greater than 20% drop 

### 7 from an individual ’ s median value: 0.89 [95% CI: 0.72, 1.10] per 30

- ppb increase in lag 1 

### 8 of 8

- h max O 3 ) and was not consistently associated with increases in respiratory 

### 9 symptoms ( Peacock et al., 2011 ) . Ozone exposure also was not consistently associated 

### 10 with decreases in lung function in a smaller panel study of 11 adults with COPD (mean 

### 11 age 67 years) ( Lagorio et al., 2006 ) . Together, these finding do not provide strong 

### 12 evidence that increases in O 3 exposure are associated wi th lung function decrements in 

### 13 adults with COPD. 

### 14

Table 6 - 9 Mean and upper percentile concentrations of ozone in epidemiologic studies examining lung function in adults with respiratory disease Study Location Years/Season O 3 Averaging Time Mean/Median Conce ntration (ppb) Upper Percentile Concentrations (ppb) Korrick et al. ( 1998 ) Mt. Washington, NH 1991, 1992 Warm season Hike
- time avg (2
- 12 h) 40 Max: 74
Khatri et al. ( 2009 ) Atlanta, GA 2003, 2005, 2006 Warm season 8
- h max 59 (median) a 75 th : 73 a Ross et al. ( 2002 ) East Moline, IL April
- October 1994 8
- h avg 41.5 Max: 78.3 Thaller et al. ( 2008 ) Galveston, TX 2002
- 2004 Warm season 1
- h max 35 (median) Max: 118 Delfino et al. ( 1997 ) Alpine, CA 1994 Warm seas on 12
- h avg personal (8:00 a.m.
- 8:00 p.m.) 18 90th: 38 Max: 80
Lagorio et al. ( 2006 ) Rome, Italy 1999 Spring and winter 24
- h avg Spring: 36.2 b Winter: 8.0 b Overall max: 48.6 b Peacock et al. ( 2011 ) London, England 1995
- 1997 All
- year 8
- h max 15.5 Autumn/Winter Max: 32 Spring/Summer Max: 74 Wiwatanadate et al. ( 2011 ) Chiang Mai, Thailand August 2005
- June 2006 24
- h avg 17.5 90th: 26.82 Max: 34.65 Park et al. ( 2005a ) Incheon, Korea March
- June 2002 24
- h avg Dust event days: 23.6 Control days: 25.1 NR NR = Not reported, Max = Maximum. a Individual
- level exposure 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). Populations Not Restricted to Individuals with Asthma Several studies have examined associations between ambient O 3 exposure and lung 

### 15 function in children; however, a limited number of studies have examined other 

### 16Draft

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- 45 September 2011 populations not restricted to individuals with asthma or other healthy populations. 

### 1 Characteristics and ambient O 3 concentration data from studies not restricted to 

### 2 individuals with asthma are presented in Table 6

- 10. 

### 3

Table 6 - 10 Mean and upper percentile concentrations of ozone in epidemiologic studies examining lung function in populations not restricted to individuals with asthma Study Location Years/Season Metric Mean/Median Concentration (ppb) Upper Percentile Concentrations (ppb) Alexeef et al. ( 2007 ) Alexeef et al. ( 2008 ) Greater Boston, MA 1995
- 2005 All
- year 24
- h avg 24.4 a NR
Naeher et al. ( 1999 ) Vinton, VA 1995
- 1996 Warm season 8
- h max 34.87 Max : 56.63 Avol et al. ( 1998a ) 6 southern CA communities 1994 Spring and summer 24
- h avg personal NR NR
L inn et al. ( 1996 ) Rubidoux, Upland, Torrence, CA 1992
- 1 993, 1993
- 1994 Fall and spring 24
- h avg 23 Max : 53

Gold et al. ( 1999 ) Mexico City, Mexico 1991 Winter, spring, fall 24
- h avg 52.0 Max : 103 Scarlett et al. ( 1996 ) Surrey, England 1994 Warm season 8
- h max 50.7 b Max : 128 b
Ward et al. ( 2002 ) Birmingham and Sandwell, England 1997 Winter and summer 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 1994 March
- October 30
- min max Freudenstadt median: 50.6 Villingen medi an : 32.1 Freudenstadt 95th: 89.7 Villingen 95th: 70.1 Hoppe et al. ( 2003 ) Munich, Germany 1992
- 1995 Warm season 30
- min max (1:00 p.m.
- 4:00 p.m.) High O 3 days: 70 .4 Control O 3 days: 29.8 Max (high O 3 days): 99 Max (control O 3 days): 39 Neuberger et al. ( 2004 ) Vienna, Austria June
- October 1999, January
- April 2000 NR NR NR Steinvil et al. ( 2009 ) Tel Aviv, Israel 2002
- 2007 All
- year 8
- h avg (10:00 a.m.

– 6:00 p.m.) 41.1 75 th : 48.7 Max : 72.8 Chen et al. ( 1999 ) 3 Taiwan communities 1995
- 1996 May
- January 1
- h max NR Max : 110.3 b
Son et al. ( 2010 ) Ulsan, Korea 2003
- 2007 All
- year 8
- h max 35.86 Max : 59.53
NR = Not Reported, Max = Maximum.
a Measured at central monitoring sites established by investigators. Concentations were averaged across all monitors. b Measured at subjects ’ schools where lung function measurements were performed. Children The 2006 O 3 AQCD identified children as a potentially at

- risk population based on 

### 4 consistent evidence of association between ambient O 3 exposure and decrements in FEV 1 

### 5 and PEF ( U.S. EPA, 2006b ) (Figure 6

- 8 and Table 6

- 11). No new studies in children 

### 6 without asthma are availa ble to compare with previous findings. Hoppe et al. ( 2003 ) O 3 

### 7 exposure to be associated with decreses in healthy children in Munich, Germany (Figure 

### 8 6

- 8 and Table 6

- 11). In another panel study of healthy children in Vienna, Austria, O 3 

### 9 was not associated with decrements in total lung capacity ( Neuberger et al., 2004 ) . Most 

### 10Draft

– Do Not Cite or Quote 6
- 46 September 2011 of the studies in children did not exclusively examine healthy children. However, several 

### 1 studies of children that included small proportions (4

- 10%) of children with history of 

### 2 respiratory disease or symptoms and found associations between O 3 exposure and 

### 3 decrements in lung function ( Chen et al., 1999 ; Ulmer et al., 1997 ; Scarlett et al., 1996 )

. 

### 4 Based on interactions between O 3 exposure and asthma/wheeze history, Avol et al. 

### 5 ( 1998a ) and Ward et al. ( 2002 ) did not find lung function responses to ambient O 3 

### 6 exposure to differ between children with history of asthma or wheeze and healthy 

### 7 children. Combined, these lines of evide nce indicate that the associations observed 

### 8 between ambient O 3 exposure and decreases in lung function in children are not driven by 

### 9 effects in children with asthma or respiratory symptoms, and that healthy children also 

### 10 may represent a population at incre ased risk of O 3 - associated respiratory effects. 

### 11

Results generally are presented in order of increasing mean ambient ozone concentration.
a The 95% CI was constructed using a standard error that was estimated from the p
- value. Effect estimates are from s ingle
pollutant models and are standardized to a 40
- , 30
- , and 20
- ppb increase for a 1
- h (or 30
- min) max, 8
- h max, and 24
- h avg ozone exposures, respectively. 

### Figure 6 - 8 Percent change in lung function in association with ambient ozone exposures in studies n ot restricted to children with asthma. 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
FEV 1 FVC
FEV 1 FEV1 Intraday change FEV 1 Intraday change FVC O 3 Lag
0 0
0

1
1 0 (personal)

- 10
- 8
- 6
- 4
- 2 0 2 Percent change in lung function parameter per standardized increment in O 3 (95% CI)Draft

– Do Not Cite or Quote 6
- 47 September 2011 

### Table 6 - 11 Additional characteristics and quantitative data for studies represented in Figure 6 - 8 and results from other studies in children Study Location/ Population O 3 Lag O 3 Averaging Time Parameter Effect Estimate (95% CI) a
Linn et al. ( 1996 ) 3 southern CA communities Children 0 1
- h avg Intraday cha nge FEV 1 Intraday change FVC - 0.56 (
- 0.99,
- 0.12)

- 0.21 (
- 0.62, 0.20) Hoppe et al. ( 2003 ) Munich, Germany Children 0 30
- min max (1:00 p.m. - 4:00 p.m.) FEV 1 FVC - 1.4 (
- 4.3, 1.4)

- 2.5 (
- 4.9,
- 0.10) Scarlett et al. ( 1996 ) Surrey, England Child ren 1 8
- h max FEV 1 - 0.04 (
- 0.32, 0.23) Chen et al. ( 1999 ) 3 Taiwan communities Children 1 1
- h max FEV 1 - 1.5 (
- 2.8,
- 0.12)
Avol et al. ( 1998a ) 3 southern CA communities Children 0 (personal) 24
- h avg In traday change FEV 1 Intraday change FVC - 1.4 (
- 3.8, 0.90) b

- 2.0 (
- 4.0, 0.01) b Studies of children not included in Figure 6 - 8 c Ulmer et al. ( 1997 ) Freudenstadt and Villingen, Germany Children 1 1/2
- h max FEV 1 (ml)
- 5.9 (
- 10.4, 1.3) b

Ward et al. ( 2002 ) Birmingham and Sandwell, England Children 0 0
- 6 avg 24
- h avg PEF (L/min) - 3.2 (
- 8.3, 2.0) d

- 11.1 (
- 22.0,
- 0.18) d Gold et al. ( 1999 ) Mexico City, Mexico Children 1 1
- 10 avg 24
- h avg Intraday change PEF (% change) - 0.54 (
- 1.1, 0.05)

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 standard 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 lung function or PEF was analyzed. d Effect estimates are from analyses restricted to summer months. Among the studies of children, the magnitudes of decrease in lung function per 

### 1 standardized increment in ambient O 3 exposure 1 ranged from less than 1 to 4%, a range 

### 2 similar to that estimated in children with asthma. However, in contrast with studies of 

### 3 children with asthma, studies of children in the general population did not consistently 

### 4 find that O 3 - associated decreases in lung function were accompanied by increases in 

### 5 respiratory symptoms. Gold et al. ( 1999 ) found that lag 1 of O 3 exposure was associated 

### 6 with both decreases in PEF and increases in phlegm; however, the increase in phlegm 

### 7 was associated with O 3 exposure lagged one day whereas the PEF decrement was driven 

### 8 by exposures lagged 2 to 4 days. Ozon e was weakly associated with cough and shortness 

### 9 of breath among children in England ( Ward et al., 2002 ) , and O 3 was associated with a 

### 10 decrease in respiratory symptom score among children in California ( Linn et al., 1996 )

. 

### 11 These findings indicate that while the magnitudes of O 3 - associated decrease in lung 

### 12 function may be similar in children with and without asthma, because of the higher 

### 13 overall lung function in healthy chi ldren, the decrements may not be large enough to be 

### 14 clinically significant in healthy children. 

### 15

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
- 48 September 2011 Adults In the small body of studies conducted in adults, O 3 has been associated with decrements 

### 1 in lung function in both healthy adults and those with comorbid factors (Table 6

- 12). In a 

### 2 cohort of mostly healthy women, ages 19

- 43 years, followed for one summer season, 

### 3 Naeher et al. ( 1999 ) observed associations between 8

- h max ambient O 3 expos ure and 

### 4 decreases in PEF. In a large cross

- sectional study of 2,380 healthy adults (75th percentile 

### 5 of age: 52 years) in Tel Aviv, Israel, across several lags of exposure (single day lags 0

- 7 

### 6 and 0

- 6 avg), O 3 was associated mostly with increases in FEV 1 , F VC, and FEV 1 /FVC 

### 7 ( Steinvil et al., 2009 ) . Another large cross

- sectional study was conducted in 2,102 

### 8 children and adults (mean age: 45 years) living near a petrochemical plant in Ulsan, 

### 9 Korea ( Son et al., 2010 ) . Multiple O 3 exposure metrics, including concentrations 

### 10 averaged across 13 city monitors, concentrations from the nearest monitor, inverse 

### 11 distance

- weighted concentrations, and estimates from kriging, were associated with 

### 12 decrements in lung function; however, no particular metric consistently showed a larger 

### 13 effect across the various lags of O 3 exposure examined. Lag 0

- 2 avg of 8

- h max O 3 

### 14 exposure was associat ed with the largest decrements in percent predicted FEV 1 (1.4

- point 

### 15 decrease [95% CI:

- 2.7,

- 0.08] per 30

- ppb increase in the 8

- h max of lag 0

- 2 avg O 3 

### 16 averaged across all monitors). Although the health status of subjects was not reported, the 

### 17 mean percent predicted FEV 1 in the study population was 82.85%, indicating a large 

### 18 proportion of subjects with underlying airway obstruction. Results from this study were 

### 19 not adjusted for meteorological factors and thus, confounding cannot be ruled out. 

### 20 As described in Section 6.2.1.1, controlled human exposure studies have not consistently 

### 21 found O 3 - induced decreases in lung function in older adults. In an earlier study of adults 

### 22 ages 69

- 95 years, Hoppe et al. ( 2003 ) did not find ambient O 3 exposure - associated 

### 23 decreases in lung function. However, recently, the Normative Aging Study found that 

### 24 ambient O 3 exposure was associated with decrements in FEV 1 and FVC in a group of 

### 25 older men ( Alexeeff et al., 2008 ) . This study in the Greater Boston area conducted 

### 26 spirometry once every 3 years for 10 years in 900 older men (mean [SD] age = 68.9 [7.2] 

### 27 years), most of whom were white and healthy. Among all subj ects, several lags of 24

- h 

### 28 avg O 3 exposure (1

- to 7

- day avg) were associated with decreases in FEV 1 ( Alexeeff et 

### 29 al., 2008 ) . Additionally, larger effects were estimated in adults with e levated BMI (≥ 30), 

### 30 airway hyperresponsiveness, and reduced activity in antioxidant enzymes (i.e., GSTP1 

### 31 Ile/Val or Val/Val variant) ( Alexeeff et al., 2008 ; Alexeeff et al., 2007 ) (Table 6

- 12). 

### 32 Larger O 3 - related decrements in FEV 1 and FVC also were observed in subjects with long 

### 33 GT dinucleotide rep eats in the promoter region of the antioxidant enzyme heme 

### 34 oxygenase - 1 ( Alexeeff et al., 2008 ) , which has been associated with reduced inducibility 

### 35 ( Hiltermann et al., 1998 ) . The largest O 3 - related percentages of decrease in lung function 

### 36 were observed in the group of me n with airway hyperresponsiveness and elevated BMI (

- 

### 37Draft

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- 49 September 2011 5.3% FEV 1 [95% CI:

- 8.3,

- 2.4] per 20

- ppb increase in lag 0

- 1 avg of 24

- h avg O 3 ). In 

### 1 this cohort, O 3 also was associated with decreases in lung function in adults without 

### 2 airway hyperresponsiveness and BMI < 30, indicating the effects of O 3 on lung function 

### 3 in older adults extends to healthy older adults. However, importantly, the findings may be 

### 4 generalizable only to older white men. 

### 5

Table 6 - 12 Associations between ambient ozone exposure and changes in lung function in studies of adults Study Location/ Population O 3 Lag O 3 Averaging Time Parameter O 3 Assessment Method/Subgroup Effect Estimate (95% CI) a
Son et al. ( 2010 ) Ulsan, Korea Children and adults, ages 7
- 97 yr 0
- 2 avg 8
- h max Change in % 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 Healthy adults, mean age 43 yr, 75 th %
- ile: 52 yr 0 0
- 6 avg 8
- h avg (10:00 a.m
- 6:00 p.m.) FEV 1 (ml) 40 (0, 80) 94 (33, 156) Naeher et al. ( 1999 ) Vinton, VA Healthy women, ages 19
- 43 yr 0 0
- 4 avg 24
- h avg Evening PEF (L/min) - 0. 06 (
- 0.11, 0)

- 5.1 (
- 8.7,
- 1.5) Hoppe et al. ( 2003 ) Munich, Germany Older adults, ages 69
- 95 yr 0 1 30
- min max (1:00p.m.
- 4:00p.m.) % change in evening FEV 1 0.75 (
- 2.1, 3.7) 1.2 (
- 1.3, 3.6) Alexeeff et al. ( 2008 ) Greater Boston, MA Older adults, mean (SD) age: 68.8 yr (7.3) 0
- 1 avg 24
- h avg % change in FEV 1 GSTP1 Ile/Ile GSTP1 Ile/Val Val/Val - 1.0 (
- 2.2, 0.19)

- 2.3 (
- 3.5,
- 1.0)
Alexeef et al. ( 2007 ) Greater Boston, MA Older adults, mean (SD) age: 68.8 yr (7.3) 0
- 1 avg 24
- h avg % change in FEV 1 BMI < 30 BMI ≥ 30 No AHR AHR BMI ≥ 30 and AHR - 1.5 (
- 2.5,
- 0.52)

- 3.5 (
- 5.1,
- 1.9)

- 1.7 (
- 2.7,
- 0.73)

- 4.0 (
- 6.2,
- 1.8)

- 5.3 (
- 8.2,
- 2.3) IDW = Inverse distance weighting, BMI = Body mass index, AHR = airway hyperresponsiveness. a Effect estimates are standardized to a 40
- ppb increase for 30
- min max O 3 , 30
- ppb increase for 8
- h max or 8
- h avg O 3 , and 20
- ppb increase for 24
- h avg O 3 . Confounding in epidemiologic studies of lung function The 1996 O 3 AQCD noted uncertainty regarding confounding by temperature and pollen 

### 6 ( U.S. EPA, 1996a ) ; however, studies collectively do not provide strong evidence of 

### 7 confounding by these factors. Most studies, whether they involved year

- round or 

### 8 summer - only examinations, included tem perature in statistical analyses and found 

### 9 associations between O 3 exposure and decreases in lung function. Across studies, 

### 10 temperature has shown inconsistent associations with lung function, even among studies 

### 11 conducted in the summer and in the same geographic region. For example, in studies of 

### 12 children attending summer camps conducted in the Northeast U.S., temperature was 

### 13 associated with an increase ( Berry et al., 1991 ) ( Thurston et al., 1997 ) and decrease 

### 14 ( Raizenne et al., 1987 ) in lung fun ction. In the reanalysis of six camp studies, 

### 15 investigators did not include temperature in models because temperature within the 

### 16 normal ambient range had not been shown to affect O 3 - induced lung function responses 

### 17 in controlled human exposure studies ( Kinney et al ., 1996 ) . In two summer camp studies 

### 18Draft

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- 50 September 2011 conducted in the Northeast U.S., O 3 was associated with decreases in lung function in 

### 1 models without and with temperature ( Thurston et al., 1997 ; Spektor et al., 1988a ) . In 

### 2 both studies, temperature and O 3 were measur ed on site of the camps. Spektor et al. 

### 3 ( 1988a ) estimated similar effects in a model with and without a temperature

- humidity 

### 4 index, and Thurston et al. ( 1997 ) found that compared with a univariate model, O 3 was 

### 5 associat ed with a nearly 2

- fold greater decrease in PEF when temperature was added to 

### 6 the model. 

### 7 Although evaluated in fewer studies, the evidence does not indicate that associations 

### 8 between ambient O 3 exposure and lung function are confounded by pollen. Some camp 

### 9 studies found that pollen independently was not associated with lung function decrements 

### 10 ( Thurston et al., 1997 ; Avol et al., 1990 ) . A few studi es of children with asthma with 

### 11 follow

- up over multiple seasons found O 3 to be associated with decrements in lung 

### 12 function in models that adjusted for pollen counts ( Just et al., 2002 ; Ross et al., 2002 ; 

### 13 Jalaludin et al., 2000 ; Gielen et al., 1997 ) . In these studies, large percentages of subjects 

### 14 had posit ive atopy (22

- 98%), with some studies examining large percentages of subjects 

### 15 specifically with pollen allergy ( Ross et al., 2002 ; Gielen et al., 1997 )

. 

### 16 A relatively larger number of studies provided information on potential confounding by 

### 17 copollutants such as PM 2.5 , PM 10 , NO 2 , or SO 2 . In most cases, investigators indicated that 

### 18 associations between O 3 exposure and lung function were not driven by copollu tant 

### 19 confounding; however, studies varied in how they considered confounding. Studies of 

### 20 subjects exercising outdoors indicated that ambient concentrations of copollutants such as 

### 21 NO 2 , sulfur dioxide, or acid aerosol were low and thus, not likely to confou nd the 

### 22 observed O 3 effects ( Hoppe et al., 2003 ; Brunekreef et al., 1994 ; Hoek et al., 1993 ) . In 

### 23 other studies of children with increased outdoor exposures, O 3 was consistently 

### 24 associated with decreases in lung function, whereas other pollutants such as PM 2.5 , 

### 25 sulfate, and acid aerosol individually showed variable associations across studies 

### 26 ( Thurston et al., 1997 ; Castillejos et al., 1995 ; Berry et al., 1991 ; Avol et al., 1990 ; 

### 27 Spektor et al., 1988a )

. 

### 28 Among studies that conducted copollutant modeling, associations between O 3 exposure 

### 29 and lung function decrements were observed to be robust (Figure 6

- 9 and Table 6

- 13). In 

### 30 copollutant models, O 3 effect estim ates generally fell within the 95% CI of the single



### 31 pollutant model effect estimates. Whereas some studies used the same averaging time for 

### 32 all pollutants ( Lewis et al., 2005 ; Jalaludin et al., 200 0 ) , most examined 1

- h max or 8

- h 

### 33 max O 3 exposures and 24

- h avg copollutant exposures ( Son et al., 2010 ; Chen et al., 

### 34 1999 ; Romieu et al., 1997 ; Romieu et al., 1996 ) . In a Philadelphia

- area summer camp 

### 35 study, Neas et al. ( 1999 ) was among the few studies to find that the effect of O 3 was 

### 36Draft

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- 51 September 2011 attenuated in a copollutant model. In a copollutant model with 24

- h avg sulfate, the 12

- h 

### 1 avg O 3 effect estimate was attenuated to near zero (Figure 6

- 9 and Table 6

- 13). 

### 2 In studies with copollutant modeling, ambient O 3 concentrations showed a wide range of 

### 3 correlations with concentrations of copollutants (r=

- 0.31 to 0.74). Among childr en with 

### 4 asthma in Sydney, Australia, Jalaludin et al. ( 2000 ) found low correlations of 24

- h avg O 3 

### 5 with 24

- h avg PM 10 (r = 0.13) and NO 2 (r =

- 0.31), and in two

- pollutant models, PM 10 

### 6 and NO 2 continued to be associated with increases in PEF, and O 3 continued to be 

### 7 associated with decreases in PEF. In a study of children with asthma in Detroit, MI, 24

- h 

### 8 avg O 3 was moderately correlated with 24

- h avg PM 2.5 (Pearson r= 0.57) and 24

- h avg 

### 9 PM 10 (Pearson r=0.59) ( Lewis et al., 2005 ) . Inclusion of PM 10 or PM 2.5 in models resulted 

### 10 in larger changes in O 3 effect estimates than those observed in other studies. As 

### 11 illustrated in Figure 6

- 9 and Table 6

- 13, the magnitude of change was not consistent 

### 12 between the two subgroups. Among subjects with a concurrent URI, O 3 - associated 

### 13 decreases in lowest daily FEV 1 were robust to the inclusion of PM 10 or PM 2.5 . Among CS 

### 14 users, O 3 was associated a much larger decrease in FEV 1 when PM 10 was included in the 

### 15 model ( Lewis et al., 2005 )

. 

### 16 Studies conducted in Mexico City found small changes in O 3 - associated lung function 

### 17 decrements in copollutant models, although different averaging times were used for 

### 18 different pollutants ( Romieu et al., 1997 ; Romieu et al., 1996 ) (Figure 6

- 9 and Table 6

- 

### 19 13). In these studies, O 3 was moderately correlated with co

- pollutants such as NO 2 and 

### 20 PM 1 0 (range of Pearson r = 0.38

- 0.58). Studies conducted in Asia also found that 

### 21 associations between O 3 and lung function were robust to the inclusion of weakly

- to 

### 22 moderately

- correlated copollutants ( Son et al., 2010 ; Chen et al., 1999 ) . Copollutant 

### 23 effect estimates generally were attenuated, indicating that O 3 may confound the results of 

### 24 copollutants. 

### 25 In a summer camp study conducted in Connecticut, Thurston et al. ( 1997 ) found ambient 

### 26 concentrations of 1

- h max O 3 and 12

- h avg sulfate to be highly correlated (r = 0.74), 

### 27 making it more difficult to separate their independent effects. With sulfate in the model, a 

### 28 larger decr ease in PEF was estimated for O 3 ; however, the 95% CI was much wider 

### 29 (Figure 6

- 9 and Table 6

- 13). Investigators found that the association between sulfate and 

### 30 PEF was driven by one day when the ambient concentrations of both pollutants were at 

### 31 their peak. With the removeal of this influential day, the sulfate effect was attenuated, 

### 32 whereas O 3 effects remained robust ( Thurston et al., 1997 )

. Among children with asthma 

### 33 in Th ailand, the O 3 - associated decrease in PEF was robust to the adjustment of SO 2 ; 

### 34 however, different lags were examined for O 3 (lag 5) and SO 2 (lag 4) ( Wiwatanad ate and 

### 35 Trakultivakorn, 2010 ) . Some studies did not provide quantitative results but reported that 

### 36 O 3 effects on lung function decrements remained statistically significant in models that 

### 37Draft

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- 52 September 2011 included copollutants such as PM 10 , NO 2 , sulfate, nitrate, or amm onium ( Romieu et al., 

### 1 1998a ; Brauer et al., 1996 ; Linn et al., 1996 ; Spektor e t al., 1988b )

. 

### 2

Results are presented for PEF then FEV 1 and th en in order of increasing mean ambient ozone concentration. a Information was not available to calculate 95% CI of the copollutant model. CS = corticosteroid, URI = Upper respiratory infection. Effect estima tes are standardized to a 40
- , 30
- , and 20
- ppb inc rease for 1
- h max, 12
- h avg, and 24
- h avg ozone, respectively. Black circles represent ozone effect estimates from single pollutant models, and open circles represent ozone effect estimates from copollutant model s. 

### Figure 6 - 9 Comparison of ozone - associated changes in lung function in single - and copollutant mode l s. Study
PEF Jalaludin et al. (2000)

Neas et al. (1999) a

Thurston et al. (1997)

Romieu et al. (1996)

Romieu et al. (1997) Population

Children with asthma or wheeze

Children attending camp

Children with asthma

attending camp

Children with asthma

Children with asthma O 3 exposure data

24
- h avg, Lag 0 24
- h avg, Lag 0 24
- h avg, Lag 0
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 O 3 with copollutant

None 24
- h avg PM 10 24
- h avg NO 2
None 24
- h avg sulfate
None 12
- h avg sulfate
None 24
- h avg PM 2.5
None 24
- h avg PM 10 ◄ ►

- 15
- 13
- 11
- 9
- 7
- 5
- 3
- 1 1 3 Percent change in PEF per standardized increase in O 3 (95% CI)

FEV 1 Lewis et al. (2005)

Chen et al. (1999) Children with asthma using CS

Children with asthma with URI

Children 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 None 24
- h avg PM 2.5 24
- h avg PM 10 None 24
- h avg PM 2.5 24
- h avg PM 10
None 24
- h avg NO 2 ◄ ► ►

- 15
- 13
- 11
- 9
- 7
- 5
- 3
- 1 1 3 Percent change in FEV 1 per standardized increase in O 3 (95% CI)Draft

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- 53 September 2011 

### Table 6 - 13 Additional characteristics and quantitative data for studies presented in Figure 6 - 9 Study Location/ Population O 3 Exposure Data 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 Jalaludin et al. ( 2000 ) Sydney, Australia Children with asthma or wheeze 24
- h avg Lag 0 Intraday change PEF - 0.57 (
- 1.1,
- 0.06) with 24
- h avg PM 10 ,

- 0.57 (
- 1.1,
- 0.06 ) with 24
- h avg NO 2

- 0.55 (
- 0.1,
- 0.04) Neas et al. ( 1999 ) Philadelphia, PA Children attending summer camp 12
- h avg Lag 1 Morning P EF

- 0.94 (
- 2.0, 0.08) with 24
- h avg sulfate

- 0.02 b Thurston et al. ( 1997 ) CT River Valley Children with asthma attending summer camp 1
- h max Lag 0 Intraday change PEF

- 2.8 (
- 4.9,
- 0.59) with 12
- h avg sulfate

- 11.8 (
- 31.6, 8.1) Romieu et al. ( 1996 ) Mexico City, Mexico Children with asthma 1
- h max Lag 0 Evening PEF

- 0.55 (
- 1.3, 0.19) with 24
- h avg PM 2.5

- 0.24 (
- 1.2, 0.68) Romieu et al. ( 1997 ) Mexico City, Mexico Children with asthma 1
- h max Lag 0 Evening PEF

- 0.52 (
- 1.0,
- 0.01) with 24
- h avg PM 10

- 0.79 (
- 1.4,
- 0.16) FEV 1 Lewis et al. ( 2005 ) Detroit, MI Children with asthma using CS Children with asthma with URI 24
- h avg Lag 2 Lowest daily FEV 1 0.29 (
- 4.2, 5.0)

- 6.0 (
- 11.2,
- 0.41) with 24
- h avg PM 2.5

- 0.18 (
- 11.0, 11.9) with 24
- h avg PM 10

- 13.4 (
- 17.8,
- 8.8) with 24
- h avg PM 2.5

- 5.5 (
- 10.3,
- 0.42) with 24
- h avg PM 10

- 7.1 (
- 11.3,
- 2.8) Chen et al. ( 1999 ) 3 Taiwan communities Children 1
- h max Lag 1 FEV 1

- 1.5 (
- 2.8,
- 0.12) with 24
- h avg NO 2

- 2.0 (
- 3.5, 0.42) Results not included in Figure 6 - 9 Wiwatanadate and Trakultivakorn ( 2010 ) Chiang Mai, Thailand Children with asthma 24
- h avg Lag 5 Evening PEF (L/min)

- 2.6 (
- 5.2, 0) with Lag 4 SO 2

- 3.2 (
- 6.2,
- 0.2) Son et al. ( 2010 ) Ulsan, Korea Children and adults 8
- h max Lag 0
- 2 avg (kriging) Change in % predicted FEV 1
- 1.4 (
- 2.6,
- 0.11) with PM 10

- 1.8 (
- 3.4,
- 0.25) CS = Corticosteroid, URI = Upper respiratory infection.
a Results represent percent changes in lung function parameter per the following standardized increase in ambient O 3 concentration: 40 ppb for 1
- h max O 3 , 30 ppb for 8
- h max or 12
- h avg O 3 , and 20 ppb for 24
- h avg O 3 . Several studies examined multi

- pollutant models that most often included O 3 , NO 2 , and 

### 1 either PM 2.5 or PM 10 . Ozone exposure was associated with similar or larger magnitudes of 

### 2 decrease lung function in multi

- pollutant models ( O'Connor et al., 2008 ; Thaller et al., 

### 3 2008 ; Chan and Wu, 2005 ; Romieu et al., 2002 ; Korrick et al., 1998 ; Higgins et al., 

### 4 1990 ) ; however, the independent effects of O 3 exposure are more difficult to assess in 

### 5 relation to incremental changes in more than one copollutant. 

### 6Draft

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- 54 September 2011 Summary of Ep idemiologic Studies of Lung Function The cumulative body of epidemiologic evidence strongly supports associations between 

### 1 ambient O 3 exposure and decrements in lung function in children, particularly, those with 

### 2 asthma. While little new research is availab le, previous AQCDs have presented 

### 3 epidemiologic evidence of heightened effects in children and adults exercising or 

### 4 working outdoors during periods of relatively low ambient O 3 concentrations (Table 6

- 1). 

### 5 These epidemiologic results are well

- supported by o bservations from controlled human 

### 6 exposure studies in which exposures to lower O 3 concentrations induce lung function 

### 7 decrements when combined with exercise as compared with exposures during rest. 

### 8 Recent epidemiologic investigation continued to focus on ch ildren with asthma, and most 

### 9 recent results in this population indicated associations between O 3 exposure and 

### 10 decrements in lung function (Figures 6

- 6 anf 6

- 7 and Tables 6

- 7 and 6

- 8). Based on a 

### 11 small number of within

- study comparisons of groups with and w ithout asthma, larger 

### 12 effects were not conclusively estimated for groups with asthma. It is important to note 

### 13 that most of these studies were not designed to assess between

- group differences, and in 

### 14 some studies, the high prevalence of atopy may have contr ibuted to larger associations in 

### 15 subjects without asthma ( Khatri et al., 2009 ; Barraza

- Villarreal et al., 2008 ) . A large body 

### 16 of previous studies demonstrated associations in children. Whereas the 2006 O 3 AQCD 

### 17 reported weak evidence, a new study indicates that O 3 exposure may be associated with 

### 18 decrements in lung function in older adults. 

### 19 Across the diverse populations examined in epidemiologic studies, ambient O 3 exposure 

### 20 was associated with 1

- 8% decreases in lung function per standardized increment in O 3 

### 21 concentration 1 . Larger decreases (3

- 8%) usually were observed in children with asthma 

### 22 or older adults with CS use, concurrent URI, airway hyperresponsiveness, or reduced 

### 23 activity of antioxidant enzymes. These results indicate that common comorbid and 

### 24 genetic factors may increase the risk of O 3 - associated respiratory effects. High dietary 

### 25 antioxidant intake was found to attenuate O 3 - associated lung function decre ments. Each 

### 26 of these potential susceptibility or protective factors has been examined in one to two 

### 27 populations, and further investigation in diverse populations is warranted. Heterogeneity 

### 28 in response also was demonstrated by observations that increases i n ambient O 3 exposure 

### 29 were associated with increased incidence of a greater than 10% decline in lung function 

### 30 in children with asthma ( Hoppe et al., 2003 ; Mortimer et al., 2002 ) . In considering the 

### 31 clinical significance of more subtle health outcomes such as lung function changes, it is 

### 32 important to note that a small shift in the population mean likely will have a 

### 33 disproportionate effect in the extreme ends of the distribution of lung function where 

### 34 these small magnitudes of decrease lead to clinically

- significant airway resistance or 

### 35

1 Effect estimates were standardized to a 40
- , 30
- , and 20
- ppb increase for 1
- h max, 8
- h max, and 24
- h av g O 3 .Draft

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- 55 September 2011 obstruction and where individuals likely have concurrent symptoms. Several 

### 1 epidemiologic studies have demonstrated the clinical significance of O 3 - associated lung 

### 2 function decrements, primarily in individuals with asthma, by finding concomitant 

### 3 increases in respirator y symptoms ( Khatri et al., 2009 ; Just et al., 2002 ; Mortimer et al., 

### 4 2002 ; Ross et al., 2002 ; Gielen et al., 1997 ; Romieu et al., 1997 ; Thurston et al., 1997 ; 

### 5 Romieu et al., 1996 )

. 

### 6 Collectively, epidemiologic studies have examined and found decreases in lung function 

### 7 in association with single

- day O 3 concentrations lagged from 0 to 7 days as well 

### 8 concentrations averaged over 2

- 10 day s. A large body of evidence indicates decreases in 

### 9 lung function in association with O 3 exposures over the duration of outdoor activity, 

### 10 same - day, or previous

- day O 3 exposures ( Son et al., 2010 ; Alexeeff et al., 2008 ; Lewis et 

### 11 al., 2005 ; Ross et al., 2002 ; Jalaludin et al., 2000 ; Chen et al., 1999 ; Romieu et al., 1997 ; 

### 12 Brauer et al., 1996 ; Romieu et al., 1996 ; Spektor et al., 1988b ) . Fewer studies find 

### 13 associatio ns with longer lags of ambient O 3 exposures (5

- 7 days) ( Wiwatanadate and 

### 14 Trakultivakorn, 2010 ; Hernández

- Cadena et al., 2009 ; Steinvil et al., 2009 ) . However, 

### 15 associations with multiday averages of exposure ( Son et al., 2010 ; Liu et al., 2009a ; 

### 16 Barraza

- Villarreal et al., 2008 ; O'Connor et al., 2008 ; Alexeeff et al., 2007 ; Mortimer et 

### 17 al., 2002 ; Ward et al., 2002 ; Gold et al., 1999 ; Naeher et al., 1999 ; Neas et al., 1999 ) 

### 18 indicate that exposures accumulated over several days may be importa nt. For single

- and 

### 19 multi

- day O 3 exposures, associations with lung function decrements were observed for 1

- 

### 20 h max, 8

- h max, and 24

- h avg O 3 , without a clear indication that the strength of evidence 

### 21 varied among the averaging times. Within studies, O 3 exposu re for various lag periods 

### 22 were associated with lung function decrements, possibly indicating that multiple modes 

### 23 of action may be involved in the responses. Activation of bronchial C

- fibers (Section 

### 24 5.3.2) may lead to decreases in lung function as an imme diate response to O 3 exposure, 

### 25 and increased airway hyperresponsiveness resulting from sensitization of airways 

### 26 (Section 5.3.5) may mediate lung function responses associated with the lagged or 

### 27 multiday O 3 exposures ( Peden , 2011 )

. 

### 28 Several studies found that associations with lung function decrements persisted at lower 

### 29 ambient O 3 concentrations. For exposures averaged up to 1 hour during outdoor activity, 

### 30 multiple studies in individuals engaged in outdoor activities found associations with O 3 

### 31 concentrations limited to those below 80 ppb ( Spektor et al., 1988a ; Spektor et al., 

### 32 1988b ) , 60 ppb ( Brunekreef et al., 1994 ; Spektor et al., 1988a ) , and 50 ppb ( Brunekreef et 

### 33 al., 1994 ) . Among outdoor workers, Brauer et al. ( 1996 ) found a robust association with 

### 34 daily 1

- h max O 3 concentrations below 40 ppb. For 8

- h average O 3 exposures, 

### 35 associations with lung function decrements in children with asthma were found to persist 

### 36 at concentrations less than 80 ppb in a U.S. multicity stud y (for lag 1

- 5 avg) ( Mortimer et 

### 37Draft

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- 56 September 2011 al., 2002 ) and less than 51 ppb in a study conducted in the Net herlands (for lag 2) ( Gielen 

### 1 et al., 1997 )

. 

### 2 Several studies of lung function evaluated confounding by meterological factors and 

### 3 copollutant exposures. Most O 3 effect estimates remained robust in models that adjusted 

### 4 for temperature, humidity, and co

- pollutants such as PM 2.5 , PM 10 , NO 2 , or SO 2 . Although 

### 5 examined in relative ly few epidemiologic studies, O 3 was associated with decreases in 

### 6 lung function in models that included pollen or acid aerosols. The consistency of 

### 7 association in the collective body of evidence with and without adjustment for 

### 8 copollutant exposures and met erological factors combined with evidence from controlled 

### 9 human exposure studies for the direct effect of O 3 exposure provide substantial evidence 

### 10 for the independent effects of ambient O 3 exposure on lung function decrements. 

### 11

6.2.1.3 Toxicology
The 2006 O 3 AQCD concluded that pulmonary function decrements occur in a number of 

### 12 species with acute exposures (≤ 1 week), ranging from 0.25 to 0.4 ppm O 3 ( U.S. EPA, 

### 13 2006b ) . Early work has demonstrated that during acute exposure of ~0.2 ppm O 3 in rats, 

### 14 the most commonly observed alterations are increased frequency of breathing and 

### 15 decreased tidal volume (i.e., rapid, shallow breathing). Decreased lung volumes are 

### 16 observed in rats with acute exposures to 0.5 ppm O 3 . At concentrations of ≥1 ppm, 

### 17 brea thing mechanics (compliance and resistance) are also affected. Exposures of 6 h/day 

### 18 for 5 days create a pattern of attenuation of pulmonary function decrements in both rats 

### 19 and humans without concurrent attenuation of lung injury and morphological changes, 

### 20 indicating that the attenuation did not result in protection against all the effects of O 3 

### 21 ( Wiester et al., 1996b ) . A number of studies examini ng the effects of O 3 on pulmonary 

### 22 function in rats, mice, and dogs are described in Table 6

- 13 on p. 6

- 91 of the 1996 O 3 

### 23 AQCD and Table AX5

- 11 on p. AX5

- 34 of the 2006 O 3 AQCD ( U.S. EPA, 2006b , 

### 24 1996a ) . Recent lung imaging studies using hyperpolarized 3 He provide evidence of 

### 25 ventilation abnormalities in rats following exposure to 0.5 ppm O 3 ( Crémillieux et al., 

### 26 2008 ) . Rats were exposed to 0.5 ppm O 3 for 2 or 6 days, either continuous ly (22 h/ day ) or 

### 27 alternating (12 h/ day ). Dynamic imaging of lung filling (2 mL/s) revealed delayed and 

### 28 incomplete filling of lung segments and lobes. Abnormalities were mainly found in the 

### 29 upper regions of the lungs and proposed due to the spatial distribu tion of O 3 exposure 

### 30 within the lung. Although the small number of animals used in the study (n = 3 to 

### 31 7/group) makes definitive conclusions difficult, the authors suggest that the delayed 

### 32 filling of lung lobes or segments is likely a result of an increase in airway resistance 

### 33 brought about by narrowing of the peripheral small airways. 

### 34Draft

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- 57 September 2011 

### 6.2.2 Airway Hyperresponsiveness Airway hyperresponsiveness refers to a condition in which the conducting airways 

### 1 undergo enhanced bronchoconstriction in response to a variety of s timuli. Airway 

### 2 responsiveness is typically quantified by measuring changes in pulmonary function (e.g., 

### 3 FEV 1 or specific airway resistance [sRaw]) following the inhalation of an aerosolized 

### 4 specific (allergen) or nonspecific (e.g., methacholine) bronchocon stricting agent or 

### 5 another stimulus such as exercise or cold air. Asthmatics are generally more sensitive to 

### 6 bronchoconstricting agents than nonasthmatics, and the use of an airway challenge to 

### 7 inhaled bronchoconstricting agents is a diagnostic test in ast hma. Standards for airway 

### 8 responsiveness testing have been developed for the clinical laboratory ( ATS, 2000a ) , 

### 9 although variation in methodology for administering the bronchoconstricting agent may 

### 10 affect the results ( Cockcroft et al., 2005 ) . There is a wide range of airway responsiveness 

### 11 in nonasthmatic people, and responsiveness is influenced by wide range of factors, 

### 12 including cigarette smoke, pollutant exposures, respiratory infections, occupational 

### 13 exposures, and respiratory irritants. Airways hyperresponsiveness in response to O 3 

### 14 exposure has not been examined widely in epidemiologic studies; such evidence is 

### 15 derived primarily from controlled human exposure and toxicological studies. 

### 16

6.2.2.1 Controlled Human Exposures Beyond its direct effect on lung function, O 3 exposur e causes an increase in airway 

### 17 responsiveness in human subjects as indicated by a reduction in the concentration of 

### 18 specific (e.g., ragweed) and non

- specific (e.g., methacholine) agents required to produce 

### 19 a given reduction in FEV 1 or increase in sRaw. Inc reased airway responsiveness is an 

### 20 important consequence of exposure to ambient O 3 , because the airways are then 

### 21 predisposed to narrowing upon inhalation of a variety of ambient stimuli including 

### 22 specific allergens, SO 2 , and cold air. 

### 23 Increases in airway r esponsiveness have been reported for exposures to 80 ppb O 3 and 

### 24 above. Horstman et al. ( 1990 ) evaluated airway responsiveness to methacholine in young 

### 25 healthy adults (22 M) exposed to 80, 100, and 120 ppb O 3 (6.6 h, quasi continuous 

### 26 moderate exercise, 39 L/min). Dos e - dependent decreases of 33, 47, and 55% in the 

### 27 cumulative dose of methacholine required to produce a 100% increase in sRaw after 

### 28 exposure to O 3 at 80, 100, and 120 ppb, respectively, were reported. Molfino et al. ( 1991 ) 

### 29 reported increased allergen

- specific airway responsiveness in mild asthmatics exposed to 

### 30 120 ppb O 3 (1 h resting exposure). Due to safety concerns, however, the exposures in the 

### 31 Molfino et al. ( 1991 ) study were not randomized with FA conducted first and O 3 

### 32 exposure second. Attempts to reproduce the findings of Molfino et al. ( 1991 ) using a 

### 33Draft

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- 5 8 September 2011 randomized exposure design have not f ound statistically significant changes in airway 

### 1 responsiveness at such low levels of O 3 exposure. At a considerably higher exposure to 

### 2 250 ppb O 3 (3 h, light

- to

- moderate intermittent exercise, 30 L/min), Jörres et al. ( 1996 ) 

### 3 found significant increases in specific and non

- specific airway responsiveness of mild 

### 4 asthmatics 3 h following O 3 exposure. Kehrl et al. ( 1999 ) found increased reactivity to 

### 5 house dust mite antigen in mild atopi c asthmatics 16

- 18 h after exposure to 160 ppb O 3 

### 6 (7.6 h, light quasi continuous exercise, 25 L/min). Holz et al. ( 2002 ) demonstra ting that 

### 7 repeated daily exposure to lower concentrations of 125 ppb O 3 (3 h for four consecutive 

### 8 days; intermittent exercise, 30 L/min) causes an increased response to allergen challenge 

### 9 at 20 h postexposure in allergic airway disease. 

### 10 O 3 exposure of ast hmatic subjects, who characteristically have increased airway 

### 11 responsiveness at baseline relative to healthy controls (by nearly two orders of 

### 12 magnitude), can cause further increases in responsiveness ( Kreit et al., 1989 ) . Similar 

### 13 relative changes in airway responsiveness are seen in asthmatics and healthy control 

### 14 subject exposed to O 3 despite their markedly different baseline airway responsiveness. 

### 15 Several studies ( Kehrl et al ., 1999 ; Jorres et al., 1996 ; Molfino et al., 1991 ) have 

### 16 suggested an increase in specific (i.e., allergen

- induced) airway reactivity. An important 

### 17 aspect of increased airway responsiveness after O 3 exposure is that this may represent a 

### 18 plausible link between ambient O 3 exposure and increased respiratory symptoms in 

### 19 asthmatics, and increased hospital admissions and ED visits for asthma. 

### 20 Changes in airway responsiveness after O 3 exposure app ear to resolve more slowly than 

### 21 changes in FEV 1 or respiratory symptoms ( Folinsbee and Hazucha, 2000 )

. Studies 

### 22 suggest that O 3 - induced increases in airway responsiveness usually resolve 18 to 24 h 

### 23 after exposure, but may persist in some individuals for longer periods ( Folinsbee and 

### 24 Hazucha, 1989 ) . Furthermore, in studies of repeated exposure to O 3 , changes in airway 

### 25 responsiveness tend to be somewhat less susceptible to attenuation with conse cutive 

### 26 exposures than changes in FEV 1 ( Gong et al., 1997a ; Folinsbee et al., 1994 ; Kulle et al., 

### 27 1982 ; Dimeo et al., 1981 ) . Increases in airway respon siveness do not appear to be 

### 28 strongly associated with decrements in lung function or increases in symptoms ( Aris et 

### 29 al., 1 995 ) . Recently, Que et al. assessed methacholine responsiveness in healthy young 

### 30 adults (83M, 55 F) at one d ay after exposure to 220 ppb O 3 and FA for 2.25 h (alternating 

### 31 15 min periods of rest and brisk treadmill walking). Increases in airways responsiveness 

### 32 at 1 day post

- O 3 exposure were not correlated with FEV 1 responses immediately 

### 33 following the O 3 exposure nor with changes in epithelial permeability assessed 1 day 

### 34 post

- O 3 exposure. 

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- 59 September 2011 

### 6.2.2.2 Toxicology In addition to human subjects, a number of species, including nonhuman primates, dogs, 

### 1 cats, rabbits, and rodents, have been used to examine the effect of O 3 exposure o n airway 

### 2 hyperresponsiveness. With a few exceptions, commonly used animal models have been 

### 3 guinea pigs, rats, or mice acutely exposed to O 3 concentrations of 1 to 3 ppm to induce 

### 4 airway hyperresponsiveness. These animal models are helpful for determining underlying 

### 5 mechanisms of general airway hyperresponsiveness and are relevant for understanding 

### 6 airway responses in humans. Although 1

- 3 ppm may seem like a high exposure 

### 7 concentration, based on 18 O 3 (oxygen

- 18

- labeled ozone) in the BALF of humans and rats, 

### 8 an exposure of 0.4 ppm O 3 in exercising humans appears roughly equivalent to an 

### 9 exposure of 2 ppm in resting rats ( Hatch et al., 1994 )

. 

### 10 A limited number of studies have observed airway hyperresponsiveness in rodents and 

### 11 guinea pigs after exposure to less than 0.3 ppm O 3 . As previously reported in the 2006 O 3 

### 12 AQCD, one study demonstrated that a very low concentration of O 3 (0.05 ppm for 4 h) 

### 13 induced airway hyperresponsiveness in some of the nine strains of rats tested ( Depuydt et 

### 14 al., 1999 ) . This effect occurred at a concentration of O 3 that was much lower than has 

### 15 been reported to induce airway hyperresponsiveness in any other species. Similar to 

### 16 ozone ’ s effects on other endpoints, these observations suggest a genetic component plays 

### 17 an important role in O 3 - induced airway hyperresponsiveness in this species and warrants 

### 18 verification in other species. More recently, Chhabra and colleagues ( 2010 ) demonstrated 

### 19 that exposure of ovalbumin (OVA)

- sensitized guinea pigs to 0.12 ppm for 2 h/ day for 4 

### 20 weeks produced specific airway hyperresponsiveness to an inhaled OVA challenge. 

### 21 Interestingly, in this study , dietary supplementation of the guine a pigs with vitamins C 

### 22 and E ameliorated a portion of the airway hyperresponsiveness as well as indices of 

### 23 inflammation and oxidative stress. Larsen and colleagues did an O 3 concentration



### 24 response study in mice sensitized by 10 daily inhalation treatments with an OVA aerosol 

### 25 ( Larsen et al., 2010 ) . Although airway responsiveness to methach oline was increased in 

### 26 non - sensitized animals exposed to a single 3

- h exposure to 0.5, but not 0.1 or 0.25, ppm 

### 27 O 3 , airway hyperresponsiveness was observed after exposure to 0.1 and 0.25 ppm O 3 in 

### 28 OVA

- sensitized mice. Shore and colleagues ( Johnston et al., 2005b ) have also 

### 29 demonstrated O 3 - induced airway hyperresponsiveness in mice after exposure to 0.3 ppm 

### 30 O 3 for 3 hours. Mice that were exposed to the same concentration of O 3 for 72 hours 

### 31 showed no evidence of airway hyperresponsiveness, indicating attenuation of this effect. 

### 32 Thus, recent toxicological studies have demonstrated that O 3 - induced airway 

### 33 hyperresp onsiveness occurs in guinea pigs and mice after either acute or repeated 

### 34 exposure to relevant concentrations of O 3 . 

### 35Draft

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- 60 September 2011 The mechanisms by which O 3 enhances the airway responsiveness to either specific (e.g., 

### 1 OVA) or non

- specific (e.g., methacholine) bronchopro vocation are not clear, but appear 

### 2 to be associated with complex cellular and biochemical changes in the conducting 

### 3 airways. Considerable research effort has been directed towards exploring the causes of 

### 4 O 3 - induced airway hyperresponsiveness, but the major ity of such studies have been 

### 5 conducted at high concentrations of O 3 . It is clear that inflammation plays a key role in 

### 6 O 3 - induced airway hyperresponsiveness, although the precise mediators and cells that are 

### 7 involved have not been identified at relevant c oncentrations of O 3 . Because inflammation 

### 8 is likely to play a role in O 3 - induced airway hyperresponsiveness, the mechanism for this 

### 9 response may be multifactorial, involving the presence of cytokines, prostanoids, or 

### 10 neuropeptides; activation of macrophage s, eosinophils, or mast cells; and epithelial 

### 11 damage that increases direct access of mediators to the smooth muscle or receptors in the 

### 12 airways that are responsible for reflex bronchoconstriction. Johnston et al. ( 2005b ) 

### 13 demonstrated that airway hyperresponsiveness occurred in both wild type and IL

- 6 

### 14 knockout mice exposed to 0.3 ppm O 3 despite reduction in markers of lung injury and 

### 15 in flammation in O 3 - exposed IL

- 6 knockout mice. This same group of investigators has 

### 16 demonstrated the involvement of natural killer T cells, obesity, CXCR2, leptin, and IL

- 17 

### 17 in O 3 - induced airway hyperresponsiveness at exposure concentrations of 1

- 3 ppm O 3 

### 18 ( Garantziotis et al., 2010 ; Voynow et al., 2009 ; Pichavant et al., 2008 ; Williams et al., 

### 19 2007b ; Lu et al., 2006 ; Johnston et al., 2005a ; Shore et al., 2003 ) . A recent study 

### 20 demonstrated a role for m indin, an extracellular matrix protein, in the AHR response 

### 21 resulting from acute exposure to 1 ppm O 3 ( Frush et al., In Press ) . Thus, a number of 

### 22 potential mediators and cells may play a role in O 3 - induc ed airway hyperresponsiveness; 

### 23 mechanistic studies are discussed in greater detail in Chapter 5. 

### 24 In order to evaluate the ability of O 3 to enhance specific and non

- specific airway 

### 25 responsiveness, it is important to take into account the phenomenon of atte nuation in 

### 26 ozone ’ s effects. Several studies have clearly demonstrated that some effects caused by 

### 27 acute exposure are absent after repeated exposures to O 3 . The ability of the pulmonary 

### 28 system to adapt to repeated insults to O 3 is complex, however, and expe rimental findings 

### 29 for attenuation to O 3 - induced airway hyperresponsiveness are inconsistent. As described 

### 30 above, airway hyperresponsiveness was observed in mice after a 3

- h exposure but not in 

### 31 mice exposed continuously for 72 hours to 0.3 ppm ( Johnston et al., 2005b ) . However, 

### 32 the Chhabra study demonstrated O 3 - induced airway hyperresponsiveness in guinea pigs 

### 33 exposed for 2 h/day for 1 0 days ( Chhabra et al., 2010 ) . Besides the obvious species 

### 34 disparity, these studies differ in that the mice were exposed continuously for 72 hours, 

### 35 whereas the guinea pigs were exposed intermittently over 10 days, sugge sting that 

### 36 attenuation might be lost with periods of rest in between O 3 exposures. 

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- 61 September 2011 

### 6.2.3 Pulmonary Inflammation, Injury and Oxidative Stress In addition to physiological pulmonary responses, respiratory symptoms, and airway 

### 1 hyperresponsiveness, O 3 exposure has been shown to result in increased epithelial 

### 2 permeability and respiratory tract inflammation. In general, inflammation can be 

### 3 considered as the host response to injury and the induction of inflammation as evidence 

### 4 that injury has occurred. Inflammation in duced by exposure of humans to O 3 can have 

### 5 several potential outcomes: (1) inflammation induced by a single exposure (or several 

### 6 exposures over the course of a summer) can resolve entirely; (2) continued acute 

### 7 inflammation can evolve into a chronic inflamm atory state; (3) continued inflammation 

### 8 can alter the structure and function of other pulmonary tissue, leading to diseases such as 

### 9 fibrosis; (4) inflammation can alter the body ’ s host defense response to inhaled 

### 10 microorganisms, particularly in potentially susceptible populations such as the very 

### 11 young and old; and (5) inflammation can alter the lung ’ s response to other agents such as 

### 12 allergens or toxins. Except for outcome (1), the possible chronic responses have only 

### 13 been directly observed in animals expo sed to O 3 . It is also possible that the profile of 

### 14 response can be altered in persons with preexisting pulmonary disease (e.g. asthma, 

### 15 COPD) or smokers. Oxidative stress has been shown to play a key role in initiating and 

### 16 sustaining O 3 - induced inflammation . Secondary oxidation products formed as a result of 

### 17 reactions between O 3 and components of the ELF can increase the expression of 

### 18 cytokines, chemokines, and adhesion molecules and enhance airway epithelium 

### 19 permeability (Sections 5.3.3. and 5.3.4.). 

### 20

6.2.3.1 Contro lled Human Exposures As reported in studies reviewed in the 1996 and 2006 O 3 AQCDs, acute O 3 exposure 

### 21 initiates an acute inflammatory response throughout the respiratory tract which has been 

### 22 observed to persist for at least 18

- 24 hours postexposure. A meta

- analysis of 21 studies 

### 23 ( Mudway and Kelly, 2004a ) showed that neutrophils (PMN) influx in healthy subjects 

### 24 was linearly associated (p<0.01) with total O 3 dose (i.e., the product of O 3 concentration, 

### 25 exposure duration, and V E ). As with FEV 1 responses to O 3 , within individual 

### 26 inflammatory responses to O 3 are generally reproducible and correlated between repeat 

### 27 exposures ( Holz et al., 1999 ) . Some individuals also appear to be intrinsically more 

### 28 susc eptible to increased inflammatory responses to O 3 exposure ( Holz et al., 2005 )

. 

### 29 The presence of PMNs in the lung has long been accepted as a hallmark of inflammation 

### 30 and is an important indicator that O 3 causes inflammation in the lungs. Neutrophilic 

### 31 inflammation of tissues indicates activation of t he innate immune system and requires a 

### 32 complex series of events which are normally followed by processes that clear the 

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- 62 September 2011 evidence of acute inflammation. Inflammatory effects have been assessed in vivo by 

### 1 lavage (proximal airway and bronchoalveolar), bronchi al biopsy, and more recently, 

### 2 induced sputum. A single acute exposure (1

- 4 hours) of humans to moderate 

### 3 concentrations of O 3 (0.2

- 0.6 ppm) while exercising at moderate to heavy intensities 

### 4 results in a number of cellular and biochemical changes in the lung , including an 

### 5 inflammatory response characterized by increased numbers of PMNs, increased 

### 6 permeability of the epithelial lining of the respiratory tract, cell damage, and production 

### 7 of proinflammatory cytokines and prostaglandins ( U.S. EPA , 2006b ) . These changes also 

### 8 occur in humans exposed to 80 and 100 ppb O 3 for 6

- 8 hours ( Alexis et al., 2010 ; Peden 

### 9 et al., 1997 ; Devlin et al., 1991 ) . Soluble mediators of inflammation such as the cytokines 

### 10 (e.g., IL

- 6, IL

- 8) and arachidonic acid metabolites (e.g., prostaglandin [PG]E 2 , PGF 2α , 

### 11 thromboxane, and leukotrienes [LTs] such as LTB 4 ) have been measured in the BALF of 

### 12 humans exposed to O 3 . In addition to their role in inflammation, many of these 

### 13 compounds have bronchoconstrictive properties and may be involved in increased airway 

### 14 responsiveness following O 3 exposure. The possible relationship between repetitive bouts 

### 15 of acute inflammation in humans caused by O 3 and the development of chronic 

### 16 respiratory disease is unknown. 

### 17 Studies reviewed in the 2006 O 3 AQCD reported that inflammatory responses do not 

### 18 appear to be correlated with lung function responses in either asthmatic or healthy 

### 19 subjects. In healthy adults (14 M, 6 F) and asthmatic (12 M, 6 F) volunteers exposed to 

### 20 200 ppb O 3 (4 h with moderate quasi continuous exercise, V E = 44 L/min), percent PMN 

### 21 and total protein in BAL fl uids were significantly increased in the asthmatics relative to 

### 22 the healthy controls. Spirometric measures of lung function were significantly decreased 

### 23 following the O 3 exposure in both groups, but were not significantly different between 

### 24 the asthmatic an d healthy subjects. Effects of O 3 on PMN and total protein were not 

### 25 correlated with changes in FEV 1 or FVC ( Balmes et al., 1997 ; Balmes et al., 1996 )

. 

### 26 Devlin et al. ( 1991 ) exposed healthy adults (18 M) to 80 and 100 ppb O 3 (6.6 h with 

### 27 moderate quasi continuous exercise, 40 L/min). In BAL fluid collected 18 h after 

### 28 exposure to 100 ppb O 3 , significant increases in PMNs, protein, PGE2, fibronectin, IL

- 6, 

### 29 lactate dehydrogenase, and α

- 1 antitrypsin compared to FA. Similar but smaller increases 

### 30 in all mediators were found after exposure to 80 ppb O 3 except for protein and 

### 31 fibronectin. Changes in BAL markers were not co rrelated with changes in FEV 1 . Holz et 

### 32 al. ( 1999 ) examined inflammatory responses in healthy (n=21) and asthmatic (n=15) 

### 33 subjects exposed to 125 and 250 ppb O 3 (3 h, light intermittent exercise, 26 L/min). 

### 34 Significantly increased percent PMN in sputum due to O 3 exposure was observed in both 

### 35 as thmatics and healthy subjects following the 250 ppb exposure. At the lower, 125 ppb 

### 36 exposure, only the asthmatic group experienced statistically significantly increases in the 

### 37 percent PMN. Significant decrements in FEV 1 were only found following exposure t o 

### 38 250 ppb; these changes in FEV 1 did not differ significantly between the asthmatic and 

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- 63 September 2011 healthy groups, nor were changes in FEV 1 correlated with changes in PMN levels. In 

### 1 contrast to these earlier findings, Vagaggini et al. ( 2010 ) recently reported a significant 

### 2 (r=0.61, p=0.015) correlation between changes in FEV 1 and changes in sputum 

### 3 neutrophils in mild

- to

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

### 4 for 2 hours with m oderate exercise. 

### 5 The time course of the inflammatory response to O 3 in humans has not been fully 

### 6 characterized. Different markers exhibit peak responses at different times. Studies in 

### 7 which lavages were performed 1 hour after O 3 exposure (1 h at 0.4 ppm or 4 h at 

### 8 0.2 ppm) have demonstrated that the inflammatory responses are quickly initiated ( Torres 

### 9 et al., 1997 ; Devlin et al., 1996 ; Schelegle et al., 1991 ) . Inflammatory mediators and 

### 10 cytokines such as IL

- 8, IL

- 6, and PGE 2 are greater at 1 h than at 18 h post

- O 3 exposure 

### 11 ( Torres et al., 1997 ; Devlin et al., 1996 ) . However, IL

- 8 still remained elevated at 18 h 

### 12 post

- O 3 exposure (4 h at 0.2 ppm O 3 versus FA) in healthy subjects ( Balmes et al., 1996 )

. 

### 13 Schelegle et al. ( 1991 ) found increased PMNs in the “ proximal airway ” lavage at 1, 6, 

### 14 and 24 hours after O 3 exposure (4 h at 0.2 ppm O 3 ), with a peak response at 6 hours. 

### 15 However, at 18

- 24 hours after O 3 exposure, PMNs remain elevated relative to 1 hour 

### 16 postexposure ( Torres et al., 1997 ; Schelegle et al., 1991 )

. 

### 17 Alexis et al. ( 2010 ) recently reported that a 6.6

- hour exposure with moderate exercise to 

### 18 80 ppb O 3 caused increase d sputum neutrophil levels at 18 hours postexposure in young 

### 19 healthy adults (n=15; 24 ± 1 years). In a prior study, Alexis et al. ( 2009 ) found genotype 

### 20 effects on inflammatory responses but not lung function responses to a 2 h

- exposure to 

### 21 400 ppb O 3 . At 4 h post O 3 exposure, both GSTM1 genotypes had significant increases in 

### 22 sputum neutrophils with a tendency for a greater increase in GSTM1

- sufficient than null 

### 23 individuals. At 24 h postexposure, neutrophils had returned to baseline levels in the 

### 24 GSTM1

- sufficient indi viduals. In the GSTM1

- null subjects, however, neutrophil levels 

### 25 increased further from 4 h to 24 h and were significantly greater than both baseline levels 

### 26 and 24 h levels in GSTM1

- sufficient individuals. Alexis et al. ( 2009 ) found that GSTM1

- 

### 27 sufficient individuals (n=19; 24 ± 3 years) had a decrease in macrophage levels at 4

- 

### 28

- 24 hours postexposure to 400 ppb O 3 for 2 h with exercise. These studies also provide 

### 29 evidence for activation of innate immunity and antigen presentation, as discussed in 

### 30 Section 5.3.6. Effects of the expos ure apart from O 3 cannot be ruled out in the Alexis et 

### 31 al. ( 2010 ; 2009 ) studies, however, since no FA exposure was conducted. 

### 32 Kim et al. ( 2011 ) has more recently shown a significant (p < 0.001) increase in sputum 

### 33 neutrophil levels following a 6.6

- hour exposure to 60 ppb O 3 relative to FA in young 

### 34 healthy adults (13 F, 11 M; 25.0 ± 0.5 years). There was no significan t effect of GSTM1 

### 35 genotype (half GSTM1

- null) on the inflammatory responses observed in these 

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- 64 September 2011 individuals. Previously, inflammatory responses had only been evaluated down to a level 

### 1 of 80 ppb O 3 . 

### 2 Inflammatory responses to O 3 exposure have also been studied in asthmatic subjects 

### 3 ( Peden et al., 1997 ; Scannell et al., 1996 ; Basha et al., 1994 ) . In these studies, asthmatics 

### 4 showed significantly more neutrophils in BALF (18 hours postexposure) than did 

### 5 similarly exposed health y individuals. In one of these studies ( Peden et al., 1997 ) , which 

### 6 included only allergic asthmatics who tested positive for Dematophagoides farinae 

### 7 antige n, there was an eosinophilic inflammation (twofold increase), as well as 

### 8 neutrophilic inflammation (threefold increase). In a study of subjects with intermittent 

### 9 asthma exposed to 0.4 ppm O 3 for 2 hours, increases in eosinophil cationic protein, 

### 10 neutrophil elastase and IL

- 8 were found to be significantly increased 16 hours 

### 11 postexposure and comparable in induced sputum and BALF ( Hiltermann et al., 1999 )

. 

### 12 Scannell et al. ( 1996 ) also reported that IL

- 8 tends to be higher in the BALF of 

### 13 asthmatics compared to nonas thmatics following O 3 exposure, suggesting a possible 

### 14 mediator for the significantly increased neutrophilic inflammation in those subjects. 

### 15 Bosson et al. ( 2003 ) found significantly greater epithelial expression of IL

- 5, IL

- 8, 

### 16 granulocyte

- macrophage colony

- stimulating factor and epit helial cell

- derived neutrophil



### 17 activating peptide

- 78 in asthmatics compared to healthy subjects following exposure to 

### 18 0.2 ppm O 3 for 2 h. In contrast, Stenfors et al. ( 2002 ) did not dete ct a difference in the O 3 - 

### 19 induced increases in neutrophil numbers between 15 mild asthmatic and 15 healthy 

### 20 subjects by bronchial wash at the 6 h postexposure time point. However, the asthmatics 

### 21 were on average 5 years older than the healthy subjects in thi s study, and it is not yet 

### 22 known how age affects inflammatory responses. It is also possible that the time course of 

### 23 neutrophil influx differs between healthy and asthmatic individuals. Differences between 

### 24 asthmatics and healthy subjects in ozone

- mediated activation of innate and adaptive 

### 25 immune responses have been observed in two studies ( Hernandez et al., 2010 ; Bosson et 

### 26 al., 2003 ) , as discussed in Sections 6.2.5.4 and 5.4.2.2. 

### 27 Vagaggini et al. ( 2002 ) investigated the effect of prior allergen challenge on responses in 

### 28 mild asthmatics exposed for 2 h to 0.27 ppm O 3 or filtered air. At 6 h postexposure, 

### 29 eosinophil numbers in induced sputum were found to be significantly greater after O 3 

### 30 than after air exposures. Studies such as this suggest that the time course of eosinophil 

### 31 and neutrophil influx following O 3 exposure can occur at levels detectable within the 

### 32 airway lumen by as early as 6 h. They also suggest that the previous or concurr ent 

### 33 activation of proinflammatory pathways within the airway epithelium may enhance the 

### 34 inflammatory effects of O 3 . For example, in an in vitro study of primary human nasal 

### 35 epithelial cells and BEAS

- 2B cell line, cytokine production induced by rhinovirus 

### 36 i nfection was enhanced synergistically by concurrent exposure to O 3 at 0.2 ppm for 3 

### 37 hours ( Spannhake et al., 2002 )

. 

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- 65 September 2011 Mar kers from BALF following both 2 hours ( Devlin et al., 1997 ) and 4 hours ( Jorres et 

### 1 al., 2000 ; Christian et al., 1998 ) repeated O 3 exposures (up to 5 days) indicate that there is 

### 2 ongoing cellular damage irrespective of the attenuation of some cellular inflammatory 

### 3 respon ses of the airways, pulmonary function, and symptom responses. Devlin et al. 

### 4 ( 1997 ) found that several indicators of inflammation (e.g., PMN, IL

- 6, PGE 2 , fibronectin) 

### 5 were attenuated after 5 days of exposure (i.e., values were not different from FA). 

### 6 However, other markers (LDH, IL

- 8, total protein, epithelial cells) did not show 

### 7 attenuation, suggesting that tissue damage probably continues to occur during repeated 

### 8 exposure. Some cellular response s did not return to baseline levels for more than 10

- 20 

### 9 days following O 3 exposure. Christian et al. ( 1998 ) showed decreased numbers of 

### 10 neutrophils and a decrease in IL

- 6 levels in healthy adults after 4 days of exposure versus 

### 11 the single exposure to 0.2 ppm O 3 for 4 h. Jörres et al. ( 2000 ) also found both functional 

### 12 and BALF cellular responses to O 3 were ab olished at 24 hours postexposure following 

### 13 the fourth exposure day. However, levels of total protein, IL

- 6, IL

- 8, reduced glutathione 

### 14 and ortho

- tyrosine was still increased significantly. In addition, visual scores 

### 15 (bronchoscopy) for bronchitis and erythem a and the numbers of neutrophils in bronchial 

### 16 mucosal biopsies were increased. Results indicate that, despite an attention of some 

### 17 markers of inflammation in BALF and pulmonary function decrements, inflammation 

### 18 within the airways persists following repeate d exposure to O 3 . The continued presence of 

### 19 cellular injury markers indicates a persistent effect that may not necessarily be recognized 

### 20 due to the attenuation of spirometric and symptom responses. 

### 21 A number of studies show that O 3 exposures increase epith elial cell permeability through 

### 22 direct (technetium

- 99m labeled diethylene triamine pentaacetic acid, 99m Tc

- DTPA, 

### 23 clearance) and indirect (e.g., increased BALF albumin, protein) techniques. Kehrl et al. 

### 24 ( 1987 ) showed increased 99m Tc

- DTPA clearance in healthy young adults at 75 minutes 

### 25 postexposure to 0.4 ppm O 3 for 2 hours. Foster and Stetkiewicz ( 1996 ) have shown that 

### 26 increased 99m Tc

- DTPA clearance persists for at least 18

- 20 hours post

- O 3 exposure (130 

### 27 minutes to average O 3 concentration of 0.24 ppm), and the effect is greater at the lung 

### 28 apices than at the base. Increased BALF protein, suggesting O 3 - induced changes in 

### 29 epithelial permeability, have also been reported at 1 hour and 18 hours postexpos ure 

### 30 ( Devlin et al., 1997 ; Balmes et al., 1996 ) . Meta

- analysis of results from 21 publications 

### 31 ( Mudway and Kelly, 2004a ) , showed that i ncreased BALF protein is associated with total 

### 32 inhaled O 3 dose (i.e., the product of O 3 concentration, exposure duration, and V E ). 

### 33 It has been postulated that changes in permeability associated with acute inflammation 

### 34 may provide increased access of inhaled antigens, particles, and other inhaled substances 

### 35 deposited on lung surfaces to the smooth muscle, interstitial cells, and the blood. Hence, 

### 36 increases in epithelial permeability following O 3 exposure might lead to increases in 

### 37 airway responsiveness to specific and nonspecific agents. Que et al. investigated this 

### 38Draft

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- 66 September 2011 hypothesis in healthy young adults (83M, 55 F ) exposed to 220 ppb O 3 for 2.25 h 

### 1 (alternating 15 min periods of rest and brisk treadmill walking). As has been observed by 

### 2 others for FEV 1 responses, within individual changes in permeability were correlated 

### 3 between sequential O 3 exposures. This indicate s differences in susceptibility to epithelial 

### 4 damage from O 3 exposure among individuals. Increases in epithelial permeability at 1 

### 5 day post

- O 3 exposure were not correlated with FEV 1 responses immediately following 

### 6 the O 3 exposure nor with changes in airway responsiveness to methacholine in assessed 1 

### 7 day post

- O 3 exposure. The authors concluded that changes in FEV 1 , permeability, and 

### 8 airway responsiveness following O 3 exposure were relatively constant over time in young 

### 9 healthy adults; although, these respon ses appear to be mediated by differing physiologic 

### 10 pathways. 

### 11

6.2.3.2 Epidemiology
In the 2006 O 3 AQCD, epidemiologic evidence of changes in pulmonary inflammation in 

### 12 association with short

- term ambient O 3 exposure (30

- min or 1

- h max) was limited to 

### 13 observations o f increases in nasal lavage levels of inflammatory cell counts, eosinophilic 

### 14 cationic protein, and myeloperoxidases ( U.S. EPA, 2006b ) . As a result of the 

### 15 development of less invasive methods to collect exhaled breath samples repeatedly f rom 

### 16 individuals in the field, the number of studies assessing ambient O 3 - related changes in 

### 17 lower airway inflammation and oxidative stress in recent years has increased 

### 18 dramatically. Although most of the biomarkers examined in these studies were not 

### 19 specif ic to the lung, most studies collected exhaled breath, exhaled breath condensate 

### 20 (EBC), nasal lavage fluid, or induced sputum with the aim of monitoring inflammatory 

### 21 responses in airways, as opposed to monitoring systemic responses in blood. These recent 

### 22 s tudies form a larger base to establish coherence with findings from human experimental 

### 23 and animal toxicological studies that have measured similar or related endpoints and 

### 24 provide further biological plausibility for associations of ambient O 3 exposure with 

### 25 respiratory symptoms and lung function decrements. These biological markers also allow 

### 26 the assessment of short

- term O 3 - related acute respiratory effects in populations that are 

### 27 less likely to experience respiratory symptoms, including healthy populations and groups 

### 28 with increased outdoor exposures. 

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- 67 September 2011 

### Table 6 - 14 Mean and upper percentile ozone concentrations in studies examining biological markers of pulmonary inflammation and oxidative stress Study Location Years O 3 Averaging Time Mean /Median Concentration (ppb) Upper Percentile Concentrations (ppb) Qian et al. ( 2009 ) Boston, MA; New York, NY; Denver, CO; Philadelphia, PA; San Francisco, CA; Madison, WI (SOCS) 1997
- 1999 All
- year 8
- h max 33.6 75th: 44.4, Max: 91.5

Khatri et al. ( 2009 ) Atlanta, GA 2003, 2005, 2006 Warm season 8
- h max 59 a Max : 73 a

Ferdinands et al. ( 2008 ) Atlanta, GA 2004 Warm season 1
- h max 61 (median) 75th: 67 Adamkiewicz et al. ( 2007 ) Steubenville, OH 2000 Cold season 24
- h avg 1
- h avg b 15.3 19.8 75 th : 20.2, Max: 32.2 75 th : 27.5, Max: 61.6 Berhane et al. ( 2011 ) 13 Southern California Communities September 2004
- June 2005 8
- h avg (10:00 a.m.
- 6:00 p.m.) NR NR
Delfino et al. ( 2010a ) Los Angeles, CA 20 05
- 2007 All
- year 24
- h avg Warm season: 33.3 Cool season: 20.6 Max : 76.4 Max: 44.9 Liu et al. ( 2009a ) Windsor, ON, Canada 2005 Cold season 24
- h avg 13.0 95 th : 26.5 Sienra
- Monge et al. ( 2004 ) Mex ico City, Mexico 1999
- 2000 All
- year 8
- h max 66.2 Max : 142.5 Barraza
Villarreal et al. ( 2008 ) Mexico City, Mexico 2003
- 2005 All
- year 8
- h max 31.6 Max (8
- h max): 86.3

Romieu et al. ( 2 008 ) Mexico City, Mexico 2004 All
- year 8
- h max 31.1 75 th : 38.3 Max: 60.7 Nickmilder et al. ( 2007 ) southern Belgium 2002 Warm season 1
- h max 8
- h max NR NR Max (across 6 camps): 24.5
- 112.7 c Max (across 6 camps): 18.9
- 81.1 c Chimenti et al. ( 20 09 ) Sicily, Italy NR All
- year 8
- h avg (7:00 a.m. - 3 :00 p.m. ) Fall: 32.7 (pre
- race), 35.1 (race) c Winter: 37.0 (pre
- race), 30.8 (race) c Summer: 51.2 (pre
- race), 46.1 (race) c NR

Max = Maximum, NR = Not Reported.
a Individual
- level exposure estimates were derived based on time spent in the vicinity of various O 3 monitors. b Average O 3 oncentration in the 1 h preceding eNO collection.
c Concentrations converted from μg/m 3 to ppb using the conversion factor of 0.51 assuming standard temperature (25°C) and pre ssure (1 atm).Draft

– Do Not Cite or Quote 6
- 68 September 2011 Results are presented first for children with asthma followed by results for adults with asthma and older adults. Effect esti mates are from single
- pollutant models and are standardized to a 30
- ppb increase for 8
- h max or 8
- h avg ozone exposures and a 20
- ppb increase for 24
- h avg ozone exposures. 

### Figure 6 - 10 Percent change in exhaled nitric oxide (eNO) per standardized increment in ambient ozone exposure in studies of individuals with and without asthm a . Study

Individuals with asthma Liu et al. (2009)

Barraza
- Villarreal et al. (2008)

Qian et al. (2009) Berhane et al. (2011)

Khatri et al. (2009)

Older adults Adamkiewicz et al. (2004)
Delfino et al. (2010) Population

Children with asthma

Children

Children and adults with asthma Children

Adults with asthma

Older adults

Older adults O 3 Lag

0

0

0 0
- 22 cum avg

2

0

0
- 4 avg Subgroup

Without asthma With asthma

Without asthma With asthma Without allergy With allergy

Cool season Warm season ◄

◄ ► ►

►

►

- 20
- 10 0 10 20 30 40 50

Percent change in eNO per standardized increment in O 3 (95% CI)Draft

– Do Not Cite or Quote 6
- 69 September 2011 

### Table 6 - 15 Additional characteri stics and quantitative data for studies represented in Figure 6 - 10
Study Location/ Population O 3 Lag O 3 Averaging Time Subgroup Standardized Percent Change (95% CI) a Studies in individuals with asthma Liu et al. ( 2009a ) Windsor, ON, Canada Children with asthma 0 24
- h avg
- 17.0 (
- 30.3,
- 1.1)
Barraza
- Villarreal et al. ( 2008 ) Mexico City, Mexico Children 0 8
- h max Without asthma With asthma 13.5 (11.2, 15.8) 6.2 (6.0, 6.5) Berhane et al. ( 2011 ) 12 Southern California communities Children 0
- 22 cum avg 8
- h avg (10:00 a.m.
- 6:00 p.m.) 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 ) 6 U.S. communities Children and adults with asthma 0 8
- h max
- 1.2 (
- 1.7,
- 0.64)
Khatri et al. ( 2009 ) Atlanta, GA Adults with asthma 2 8
- h max 36.6 (1.2, 71.9) Studies in older adults Adamkiewicz et al. ( 2007 ) Steubenville, Ohio Older adults 0 24
- h avg
- 5.7 (
- 25.9, 14.5) Delfino et al. ( 2010a ) Los Angeles, CA Older adults 0
- 4 avg 24
- h avg Cool season Warm season 23.6 (7.3, 39.9)

- 0.58 (
- 13.4, 12.3)
a Effect estimates are standardized to a 30
- ppb increase for 8
- h max or 8
- h avg O 3 and a 20
- ppb increase for 24
- h avg O 3 .



### Table 6 - 16 Associations between short - term ambient ozone exposure and biological markers of pulmonary inflammation and oxidative stress Study Location/ Population O 3 Lag O 3 Averaging Time Biological Marker Subgroup Effect Estimate (95% CI) a Liu et al. ( 2009a ) Windsor, ON, Canada Children with asthma 0 24
- h avg EBC 8
- isoprostane (% change) EBC TBARS (% change) 10.2 (
- 9.2, 33.5) 7.2 (
- 18.3, 40.7)
Romieu et al. ( 2008 ) Mexico City, Mexico Children with asthma 0 8
- h max EBC MDA b 1.3 (1.0, 1.7) Barraza
- Villarreal et al. ( 2008 ) Mexico City, Mexico Children 0 8
- h max Nasal lavage IL
- 8 (pg/ml) EBC pH Without asthma With asthma Without asthma With asthma 1.6 (1.4, 1.8) 1.6 (1.4, 1.9)

- 0.10 (
- 0.27, 0.08) c

- 0.10 (
- 0.20, 0.01) c Sienra
- Monge et al. ( 2004 ) Mexico City, Mexico Children with asthma 0
- 2 avg 8
- h max Nasal lavage IL
- 8 b Nasal lavage IL
- 6 b Nasal lavage Uric acid b Nasal lavage GSx b Placebo Antioxidant Placebo Antioxidant Placebo Antioxidant Placebo Antioxidant 1.4 (1.0, 2.0) 1.0 (0.70, 1.5) 1.5 (1.2, 2.0) 1.0 (0.76, 1.4) 0.88 (0.70, 1.1) 1.1 (0.84, 1.5) 0.90 (0.82, 0.99) 0.91 (0.83, 0.98) Khatri et al. ( 2009 ) Atlanta, GA Adults with asthma 2 8
- h max Blood eosinophils (% change) 2.4 (0.62, 4.2) Ferdinands et al. ( 2008 ) Atlanta, GA Children exercising outdoors 0 1
- h max EBC pH 2.5 (
- 0.20, 5.1) c
EBC = exhaled breath condensate, TBARS = thiobarbituric acid reactive substances, MDA = malondialdehyde, IL
- 8 = interleukin 8, IL
- 6 = interleukin 6, Antioxidant=group supplemented with vitamins C and E, GSx = glutathione.

a Effect estimates are standardized to a 40
- , 30
- and 20
- ppb increase for 1
- h max, 8
- h max, and 24
- h avg O3, respectively b Models analyzed log
- transformed biological markers. Therefore, effect estimates represent the ratio of the geometric means of biological markers for a standardized increase in O 3 exposure. An estimate less than 1 indicates a decrease in pulmonary inflammat ion or oxidative stress for an increase in O 3 exposure, and an estimate greater than 1 indicates an increase in pulmonary inflammation or oxidative stress for an increase in O 3 exposure.

c Negative and positive effect estimates indicate increases and decrea ses in pulmonary inflammation, respectively.Draft

– Do Not Cite or Quote 6
- 70 September 2011 Despite the strengths of biomarker studies, it is important to note that research in this 

### 1 field continues to develop, and several uncertainties are recognized that may limit the 

### 2 interpretations of associations between ambient O 3 exposure and changes in biomarker 

### 3 levels. Current areas of development include examination of the clinical relevance of the 

### 4 observed magnitudes of changes in biological markers of pulmonary inflammation 

### 5 ( Murugan et al., 2009 ; Duramad et al., 2007 ) , characterization of the time course of 

### 6 changes between biomarker levels and other endpoints of respiratory morbidity, 

### 7 development of standar dized methodologies for collection, improvement of the 

### 8 sensitivity and specificity of assay methods, and characterization of subject factors (e.g., 

### 9 asthma severity and recent medication use) that contribute to inter

- individual variability. 

### 10 These sources of uncertainty may contribute to differences in findings among studies. 

### 11 In recent epidemiologic studies, the biomarker most frequently measured was exhaled 

### 12 nitric oxide (eNO), likely related to its ease of collection in the field and automated 

### 13 measurement. O ther biological media analyzed included EBC, induced sputum, and nasal 

### 14 lavage fluid, all of which are hypothesized to contain aerosolized particles and/or cells 

### 15 from fluid lining the lower and upper airways ( Balbi et al., 2007 ; Howarth et al., 2005 ; 

### 16 Hunt, 2002 ) . These fluids contain cytokines, cells, and markers of oxidative stress that 

### 17 mediate inflammatory responses. In particul ar, several of the cytokines, cells, and 

### 18 markers of oxidative stress examined in epidemiologic studies also have been examined 

### 19 in controlled human exposure and toxicological studies.Table 6

- 14 presents the 

### 20 characteristics and ambient O 3 concentration data from recent studies assessing 

### 21 associations between O 3 exposure and biological markers of pulmonary inflammation and 

### 22 oxidative stress. Many recent studies reported positive associations between short

- term 

### 23 ambient O 3 exposure and increases in pulmonary infla mmation and oxidative stress, in 

### 24 particular, studies of children with asthma conducted in Mexico City (Figure 6

- 10 and 

### 25 Tables 6

- 15 and 6

- 16). 

### 26
Populations with Asthma Exhaled Nitric Oxide Nitric oxide or eNO has not been examined in controlled human exposur e or 

### 27 toxicological studies of O 3 exposure. However, several lines of evidence support its 

### 28 analysis as an indicator of pulmonary inflammation in epidemiologic studies. Inducible 

### 29 nitric oxide synthase can be activated by pro

- inflammatory cytokines, and NO ca n be 

### 30 produced by cells such as neutrophils, eosinophils, and epithelial cells in the lung during 

### 31 an inflammatory response ( Barnes and Liew, 1995 ) . Additional support is provided by 

### 32 observations of higher eNO in individuals with asthma, an d increases in the levels during 

### 33 acute exacerbations ( Jones et al., 2001 ; Kharitonov and Barnes, 2000 )

. 

### 34Draft

– Do Not Cite or Quote 6
- 71 September 2011 As indicated in Figure 6

- 10 and Table 6

- 15, several studies found that short

- term ambient 

### 1 O 3 exposure (8

- h max or avg) was associated with increases in eNO in children with 

### 2 asthma. Liu et al. ( 2009a ) (described in Section 6.2.1.2) reported O 3 - associated decreases 

### 3 in eNO; however, this study was restricted to winter months. I n this study, results for 

### 4 EBC levels of TBARS and 8

- isoprostane as well as lung function did not provide strong 

### 5 evidence of O 3 effects on airway oxidative stress. 

### 6 The two studies that compared children with and without asthma did not find larger O 3 - 

### 7 associ ated increases in eNO in children with asthma (Figure 6

- 10 and Table 6

- 15). 

### 8 Among children in Southern California, Berhane et al. ( 2011 ) examined a 0

- 22 day 

### 9 cumulative average of 8

- h avg (10 :00 a.m.

- 6:00 p.m.) O 3 and estimated similar effects for 

### 10 children with and without asthma and children with and without allergy. Among children 

### 11 in Mexico City, Barraza

- Villarreal et al. ( 2008 ) examined lag 0 of 8

- h max O 3 and 

### 12 estimated larger effects for children without asthma. 

### 13 In the two studies that includ ed adults with asthma, ambient O 3 exposure was associated 

### 14 with both decreases and increases in eNO ( Khatri et al., 2009 ; Qian et al., 2009 ) . In the 

### 15 multicity salmeterol (β

- 2 adrenergic agonist) trial (Boston, MA; New York, NY; Denver, 

### 16 CO; Philadelphia, PA; San Francisco, CA; and Madison, WI), eNO was collected every 

### 17 2

- 4 weeks over a 1 6

- week period from 119 subjects with persistent asthma, 87% of 

### 18 whom were 20

- 65 years of age ( Qian et al., 2009 ) . Among all subjects, lag 0 of 8

- h max 

### 19 O 3 was associated with a decrease in eNO as were exposures lagged 1 to 3 days and 

### 20 averaged over 5 days. Results did not vary among the salmeterol, CS, and placebo 

### 21 groups, indi cating that the counterintuitive findings for O 3 were not simply due to the 

### 22 reduction of inflammatory responses by medication use. The authors suggested that at 

### 23 higher O 3 exposures, O 3 may rapidly react with NO in airways to form reactive nitrogen 

### 24 species such as peroxynitrite. However, in the other study of adults with asthma, ambient 

### 25 concentrations of 8

- h max O 3 were higher, and a positive association was found with 

### 26 eNO ( Khatri et al., 2009 ) . In this study conducted during a summer season in Atlanta, 

### 27 GA, a 30

- ppb increase in lag 2 of 8

- h max O 3 was associated with a 36.6% increase in 

### 28 eNO (95% CI: 1 .2, 71.9). These findings should be interpreted with caution as they were 

### 29 based on a single eNO measurement per subject and were not adjusted for any 

### 30 meteorological factors. 

### 31 Other biological markers of pulmonary inflammation and oxidative stress As indicat ed in Table 6

- 16, studies have found associations between short

- term ambient 

### 32 O 3 exposure and changes in the levels of proinflammatory cytokines and cells, indicators 

### 33 of oxidative stress, and antioxidants. Importantly, any particular endpoint was examined 

### 34 o nly in one to two studies, and the evidence in individuals with asthma is derived 

### 35 primarily from studies conducted in Mexico City ( Romieu et al., 2009 ; Barraza

- Villarreal 

### 36Draft

– Do Not Cite or Quote 6
- 72 September 2011 et al., 2008 ; Romieu et al., 2008 ; Sienra

- Monge et al., 2004 ) . Despite the limited 

### 1 evidence, the epidemiologic observations are well

- supported by controlled human 

### 2 exposure and toxicological studies that have meas ured analogous endpoints. 

### 3 Several of the modes of action of O 3 are mediated by secondary oxidation products 

### 4 produced in the airways by O 3 (Section 5.3.3). Reactive oxygen species (ROS) are 

### 5 involved in the regulation of inflammation via regulation of the e xpression of cytokines 

### 6 and activity of inflammatory cells in airways ( Heidenfelder et al., 2009 ) . In controlled 

### 7 human exposure and toxicological studies, prostaglandins have been frequently measured 

### 8 to indicate O 3 - induced increases in oxidative stre ss (Sections 5.3.3 and 6.2.3.1). 

### 9 Prostaglandins are produced by the peroxidation of arachidonic acid in cell membranes 

### 10 ( Morrow et al., 1990 ) . Romieu et al. ( 2008 ) analyzed biweekly samples of EBC 

### 11 malondialdehyde (MDA), a thiobarbituric acid reactive substance, which like 

### 12 prostaglandins, is derived from oxidative degradation of lipids ( Janero, 1 990 ) . The ratio 

### 13 of the geometric means of MDA was 1.3 (1.0, 1.7) per a 30

- ppb increase in lag 0 of 8

- h 

### 14 max O 3 . Similar results were reported for lags 1 and 0

- 1 average exposures. An important 

### 15 limitation of the study was that 25% of EBC samples had nonde tectable levels of MDA. 

### 16 Thus, the random assignment of concentrations between 0 and 4.1 nmol may have 

### 17 contributed random measurement error to the estimated O 3 effects. Because MDA 

### 18 represents less than 1% of lipid peroxides and is present at low concentrati ons, its 

### 19 reliability as a marker of oxidative stress in vivo has been questioned. However, Romieu 

### 20 et al. ( 2008 ) pointed to their obse rvations of statistically significant associations of EBC 

### 21 MDA levels with nasal lavage IL

- 8 levels to support its analysis as a biologically



### 22 relevant indicator of pulmonary inflammation. 

### 23 Uric acid and glutathione are ROS scavengers that are present in the airway ELF. While 

### 24 the roles of these markers in the inflammatory cascade of asthma are not well 

### 25 characterized, they are observed to be consumed in response to short

- term O 3 exposure in 

### 26 controlled human exposure and animal studies (Section 5.3.3). Results f rom an 

### 27 epidemiologic study also indicate that ambient O 3 exposure may stimulate an antioxidant 

### 28 response. In a panel study with three measurements of nasal lavage at 3

- week intervals, 

### 29 Sienra

- Monge et al. ( 2004 ) found O 3 - associated decreases in nasal lavage levels of uric 

### 30 acid and glutathione in children with asthma not supplemented with antioxidant vitamins 

### 31 (Table 6

- 16). The magnitude of association was similar for O 3 exposures lagged 2 or 3 

### 32 days and averaged over 3 days. 

### 33 Both controlled human exposure and toxicological st udies find O 3 - induced increases in 

### 34 the cytokines IL

- 6 and IL

- 8 (Sections 5.3.3, 6.2.3.1, and 6.3.3.3), which are involved in 

### 35 initiating an influx of neutrophils, a hallmark of inflammation induced by short

- term O 3 

### 36 exposure. Recent epidemiologic studies pro duced similar findings. Barraza

- Villarreal 

### 37Draft

– Do Not Cite or Quote 6
- 73 September 2011 et al. ( 2008 ) observed that a 30

- ppb increase in lag 0 of 8

- h max O 3 was associated with a 

### 1 1.61 pg/ml increase (95% CI: 1.4, 1.8) in IL

- 8. In another study of children with asthma 

### 2 in Mexico City, Sienra

- Monge et al. ( 2004 ) found that lags 2, 3, and 0

- 2 avg of 8

- h max 

### 3 O 3 were associate d with increases in nasal lavage levels of IL

- 6 and IL

- 8 (placebo group), 

### 4 with the largest effects estimated for lag 0

- 2 average exposure (Table 6

- 16). 

### 5 Neutrophil influx has been a prominent characterisitc of O 3 - induced inflammation; 

### 6 however, controlled hu man exposure studies also have found O 3 - induced increases in 

### 7 eosinophils in adults with asthma (Section 6.2.3.1). Eosinophils are believed to be the 

### 8 main effector cells that initiate and sustain inflammation in asthma and allergy ( Schmekel 

### 9 et al., 2001 ) . Consistent with these findings, in a cross

- sectional study of adults with 

### 10 asthma in Atlanta, GA, a 30

- ppb increase in lag 0 of 8

- h max O 3 was assoc iated with a 

### 11 2.4% increase (0.62, 4.2) in blood eosinophils ( Khatri et al., 2009 ) . These result s were 

### 12 not adjusted for meteorological factors. 

### 13 The pH of EBC also was analyzed as an indicator of pulmonary inflammation. EBC pH is 

### 14 thought to reflect the proton

- buffering capacity of ammonium in airways. It has been 

### 15 widely used in the clinical assessment of asthma, is consistently lower in subjects with 

### 16 asthma, decreases upon acute asthma exacerbation (on the order of 2 units), and is 

### 17 negatively correlated with airway levels of proinflammatory cytokines ( Carpagnano et 

### 18 al., 2005 ; Kostikas et al., 2002 ; Hunt et al., 2000 ) . In addition to finding O 3 - associated 

### 19 increases in eNO and nasal lavage IL

- 8, Barraza

- Villarreal et al. ( 2008 ) found small O 3 - 

### 20 associated decreases in EBC pH (Table 6

- 16). 

### 21 The prominent influences of ROS and antioxidants in mediating the effects of O 3 provide 

### 22 biological plausibility for the effect modification by antioxidant supplementation. The 

### 23 modulation of O 3 - associated lung function by antioxidant capacity has been described in 

### 24 controlled human exposure and epidemiologic studies (Sections 6.2.1.1 and 6.2.1.2). 

### 25 Epidemiologic studies also found that higher levels of dietary or supplemented 

### 26 antioxidants attenuated inflammation and oxidative stress. Sienra

- Monge et al. ( 2004 ) 

### 27 conducted a 12 week

- trial with daily vita min C and E supplements. In the antioxidant 

### 28 group, the ratios of the geometric means of nasal lavage IL

- 6 and IL

- 8 per 30

- ppb 

### 29 increases in lag 0

- 2 avg of 8

- h max O 3 were 1.0, reflecting no increases with increases in 

### 30 O 3 exposure (Table 6

- 16). Effect modifi cation by antioxidant supplementation was not 

### 31 consistent for uric acid and glutathione (Table 6

- 16). Ozone was associated with 

### 32 increases in uric acid in the antioxidant group and decreases in the placebo group across 

### 33 O 3 lags of exposure. Associations with glutathione were similar in both groups. 

### 34 Therefore, the results do not clearly delineate the interactions among inhaled O 3 , 

### 35 endogenous antioxidants, and dietary supplementations of antioxidants. In another cohort 

### 36 of children with asthma in Mexico City, a d iet high in fruits and vegetables was found to 

### 37Draft

– Do Not Cite or Quote 6
- 74 September 2011 protect against O 3 - related increases in nasal lavage IL

- 8 ( Romieu et al., 200 9 ) . At high 

### 1 ambient O 3 levels (≥ 38 ppb, 8

- h max), a 1

- unit increase in FVI was associated with a 

### 2 0.219 pg/ml decrease (95% CI:

- 0.38,

- 0.05) in IL

- 8. The protective effect was 

### 3 diminished by about 49% at O 3 levels of 25 ppb or lower. Results from these two studies 

### 4 indicate that augmenting the circulating levels of antioxidants, through diet or vitamin 

### 5 supplements, may reduce nasal inflammation associated with high ambient O 3 exposures. 

### 6 Clinical significance of ozone - associated changes in pulmonary inflammation and oxidative stress in children with asthma While the results of epidemiologic studies in children with asthma were consistent with 

### 7 the known modes of action of O 3 in consuming antioxidants and inducing oxidative stress 

### 8 and pulmonary inflamma tion (Section 5.3.3), the clinical significance of these changes 

### 9 has not been well

- characterized. The levels of several of the biological markers such as 

### 10 eNO, EBC pH, and MDA have been shown to differ between subjects with and without 

### 11 asthma and change acu tely during an acute asthma exacerbation ( Corradi et al., 2003 ; 

### 12 Hunt et al., 2000 ) ; however, the magnitudes of change for these conditions are not well



### 13 defined. Several studies conducted in individuals with asthma found large O 3 - associated 

### 14 increases in eNO; effect estimates ranged between a 6 and 36% increase per standardi zed 

### 15 increment in ambient O 3 concentration 1 (Figure 6

- 10 and Table 6

- 15). Standardized 

### 16 increments in ambient O 3 exposure were associated with smaller (1

- 2%) increases in 

### 17 interleukins or indicators of oxidative stress ( Khatri et al., 2009 ; Barraza

- Villarreal et al., 

### 18 2008 ) ( Romieu et al., 2008 ; Sienra

- Monge et al., 2004 )

. 

### 19 Some studies permitted the evaluation of the potential clinical relevance of these changes 

### 20 in eNO through the concurrent assessment of respiratory symptoms. Am ong children 

### 21 with asthma in Mexico City, O 3 exposure was associated with increases in eNO and nasal 

### 22 lavage IL

- 8 and concurrently assessed cough but not wheeze ( Barraza

- Villarreal et al., 

### 23 2008 ) . Among adults with asthma in Atlanta, O 3 was associated with increases in eNO, 

### 24 blood eosinophils, and a decrease in quality of life score, which incorporates indices for 

### 25 symptoms, mood, and activity limitations ( Khatri et al., 2009 ) . These findings suggest 

### 26 that the more subtle O 3 - associated increases in biological markers of airway 

### 27 inflammation may be sufficient to result in respiratory s ymptoms or activity limitations. 

### 28

Children without Asthma Recent studies found that short

- term O 3 exposure (8

- h max or avg) was associated with 

### 29 indicators of airway inflammation in children without asthma ( Berhane et al., 2011 ; 

### 30 Barraza

- Villarreal et al., 2008 ) (Figure 6

- 10 and Tables 6

- 15 and 6

- 16). In the panel 

### 31

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
- 75 September 2011 study of children in Mexico City, O 3 exposure was associated with a larger increase in 

### 1 eNO in the children without asthma than with asthma (13.5% ve rsus 6.2% increase per 

### 2 30

- ppb increase in lag 0 of 8

- h max O 3 ). Ozone was associated with similar magnitudes 

### 3 of changes in IL

- 8 and EBC pH in children with and without asthma. A distinguishing 

### 4 feature of this study was that most of the children without ast hma were atopic (72%) as 

### 5 indicated by positive skin prick tests, which may have contributed to the similar effects of 

### 6 O 3 exposure observed in children with and without asthma. 

### 7 However, the Southern California Children ’ s Health Study estimated similar effec ts for 

### 8 8

- h avg (10:00 a.m.

- 6:00 p.m.) ambient O 3 exposure on eNO in children with and without 

### 9 respiratory allergy ( Berhane et al., 2011 ) . Results from this large study (n = 2240 

### 10 children) pr ovided evidence that ambient O 3 exposure increases airway inflammation in 

### 11 healthy children. In comparison with other studies, this analysis from the Children ’ s 

### 12 Health Study provided detailed information on differences in association among various 

### 13 lags of 8

- h avg (10:00 a.m.

- 6:00 p.m.) O 3 exposure. Consistent with other studies 

### 14 examining pulmonary inflammation and oxidative stress, Berhane et al. ( 2011 ) found that 

### 15 relatively shorter lags of exposure, including 1 to 5 days, were associated with increases 

### 16 in eNO. However, in an examination of several types of lag

- based models, including 

### 17 unconstrained lag models, polynomial distributed lag models, spline

- ba sed distributed lag 

### 18 models, and cumulative lag models, investigators found that a 23

- day cumulative lag 

### 19 model best fit the data. Among the studies evaluated in the current assessment, Berhane 

### 20 et al. ( 2011 ) was unique in evaluating and finding larger effects for cumulative average 

### 21 O 3 exposures over multiple weeks (e.g., 13

- 30 days). O 3 exposures averaged over the 

### 22 several hours preceding eNO collection were not significantly associated with eNO . The 

### 23 mechanism for the effects of O 3 peaking with a 23

- day cumulative lag of exposure is not 

### 24 known. 

### 25
Populations with Increased Outdoor Exposures In a limited number of available studies, ambient O 3 exposure was not consistently 

### 26 associated with pulmonary i nflammation in populations with increased outdoor 

### 27 exposures. Important limitations of these studies include small numbers of subjects and 

### 28 repeated measurements. In a cross

- sectional study of children at camps in south Belgium, 

### 29 although O 3 was not associate d with lung function, an association was found for eNO 

### 30 ( Nickmilder et al., 2007 ) . Children at camps with lag 0 1

- h max O 3 concentrations above 

### 31 85.2 ppb had greater increases in intraday eNO compared with children at camps with O 3 

### 32 concentrations below 51 ppb. A benchmark dose analysis indicated that the threshold for 

### 33 an O 3 - induced increase of 4.3 ppb eNO (their definition of increased pulmonary 

### 34 inflammation) was 68.6 ppb for 1

- h max O 3 and 56.3 ppb for 8

- hr max O 3 . While these 

### 35 results provide additional evidenc e for O 3 - associated increases in airway inflammation in 

### 36Draft

– Do Not Cite or Quote 6
- 76 September 2011 healthy children, they should be interpreted with caution since they were not adjusted for 

### 1 any potential confounding factors. 

### 2 Recent studies examined associations of O 3 exposure with biological marke rs of airway 

### 3 inflammation in populations exercising outdoors. In a panel study of 16 adolescent long



### 4 distance runners in Atlanta, GA, lags 0, 1, and 2 of 1

- h max O 3 were associated with 

### 5 increases in EBC pH, indicating O 3 - associated decreases in pulmonary i nflammation 

### 6 ( Ferdinands et al., 2008 ) . Among 9 adult male runners in Sicily, Italy examined 3 days 

### 7 before and 20 hours after 3 races in fall, winter, and summer, weekly average O 3 

### 8 concentrations (8

- h avg, 7:00 a.m.

- 3:00 p.m.) were positively correlated with apoptosis of 

### 9 airway cells (Spearman ’ s r = 0.76, p < 0.0005) and bronchial epithel ial cell differential 

### 10 counts (Spearman ’ s r = 0.467, p < 0.05) but not with neutrophil or macrophage cell 

### 11 counts or levels of the proinflammatory cytokines TNF

- α and IL

- 8 ( Chimenti et al., 

### 12 2009 ) . Although this study provides evidence for some new endpoints , the implications 

### 13 of the findings are limited since they were not based on a rigorous statistical analysis. 

### 14

Older Adults Two panel studies examining O 3 - associated changes in eNO in older adults produced 

### 15 contrasting findings (Figure 6

- 10 and Table 6

- 15). Both studies were similar in that 

### 16 outdoor O 3 was monitored by investigators in the vicinity of subjects ’ residences, and 

### 17 cool season

- specific results were presented. However, several differences were 

### 18 noteworthy, including geographic location, inclusion of healthy subjects, and lags of O 3 

### 19 exposure examined. Delfino et al. ( 2010a ) followed 60 elderly subjects with coronary 

### 20 artery disease in the Los Angeles, CA area for two 6

- week periods, one in the warm 

### 21 season and one in the cool season, although the exact months were not specified. 

### 22 Multiday averages of O 3 (3

- to 9

- day) were associated with increases in eNO, with effect 

### 23 estimates increasing with increasing number of averaging days. In contrast with most 

### 24 o ther studies, a strong positive effect was estimated for the cooler season (4.06 ppb [95% 

### 25 CI: 1.25, 6.87]) increase in eNO per 20

- ppb increase in lag 0

- 4 of 24

- h avg O 3 ), whereas 

### 26 no association was observed for the warm season (

- 0.01 ppb change in eNO [95% CI:

- 

### 27 2.31, 2.11]). Despite these unusual findings for the cool season, they were similar to 

### 28 findings from another study of Los Angeles area adults with asthma that found O 3 effects 

### 29 (i.e., decrease in indoor activity) during the fall season ( Eiswerth et al., 2005 )

. 

### 30 Adamkiewicz et al. ( 2004 ) did not find a positive association between O 3 exposure and 

### 31 eNO in a group of older adults (ages 54

- 91 years) comprising healthy subjects and those 

### 32 with a sthma or COPD. The study was conducted in Steubenville, OH between September 

### 33 and December, and as was observed in most other studies conducted during winter 

### 34 months, O 3 (concurrent 1 hour and 24 hours preceding eNO collection) was associated 

### 35Draft

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- 77 September 2011 with decreases in eNO, indicating a decrease in pulmonary inflammation (Figure 6

- 10 

### 1 and Table 6

- 16). 

### 2
Confounding in Epidemiologic Studies of Pulmonary Inflammation and Oxidative Stress Except where noted in the preceding text, most epidemiologic studies of pulmonary 

### 3 infl ammation and oxidative stress accounted for the potential for confounding by 

### 4 meteorological factors. Ambient O 3 exposure was associated with pulmonary 

### 5 inflammation or oxidative stress in models that adjusted for temperature and/or humidity 

### 6 ( Delfino et al., 2010a ; Barraza

- Vill arreal et al., 2008 ; Romieu et al., 2008 ) . Most studies 

### 7 conducted over multiple seasons adjusted for season or time trend. Sienra

- Monge et al. 

### 8 ( 2004 ) and Berhane et al. ( 2011 ) did not adjust for temperature in their final results after 

### 9 finding that the inclusion of temperature did not change results. 

### 10 Although information is limited to a small number of studies conducted in Mexico City, 

### 11 the evidence does not indicate the confounding of O 3 associations by PM 2.5 or PM 10 

### 12 exposure. In these studies, whic h analyzed 8

- h averages for both O 3 and PM and reported 

### 13 moderate correlations between pollutants (r=0.46

- 0.54), robust associations were found 

### 14 for O 3 ( Barraza

- Villarreal et al., 2008 ; Romieu et al., 2008 ; Sienra

- Monge et al., 2004 )

. 

### 15 Only Romieu et al. ( 2008 ) provided quantitative results. Lag 0 of 8

- h max O 3 was 

### 16 associated with the same magnitude of incre ase in MDA with and without lag 0 of 8

- h 

### 17 max PM 2.5 in the model (ratio of geometric means per 30

- ppb increase: 1.3 [95% CI: 1.0, 

### 18 1.7]). In the copollutant model, the effect estimate for PM 2.5 was cut in half. 

### 19
Summary of Epidemiologic Studies of Pulmonary Inflammation and Oxidative Stress Many recent epidemiologic studies reported positive associations between short

- term 

### 20 ambient O 3 exposure and increases in pulmonary inflammation and oxidative stress, 

### 21 particularly, studies of children with asthma in Mexico City. By also finding that O 3 - 

### 22 associated increases in pulmonary inflammation were attenuated with higher antioxidant 

### 23 intake, these studies, as a whole, provided evidence that inhaled O 3 may be an important 

### 24 source of ROS in airways and/or may increase airwa y inflammation via oxidative stress



### 25 mediated mechanisms. Studies also indicated that ambient O 3 exposure may increase 

### 26 airway inflammation in healthy children ( Berhane et al., 2011 ; Nickmilder et al., 2007 )

. 

### 27 The limited available evidence in subjects exercising outdoors and older adults was 

### 28 inconclusive. Temperature and humidity were not found to confound O 3 associations, and 

### 29 in the few studies that evaluated copollut ant models, O 3 effect estimates were robust to 

### 30Draft

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- 78 September 2011 inclusion of PM 2.5 or PM 10 ( Barraza

- Villarreal et al., 2008 ; Romieu et al., 2008 ; Sienra



### 1 Monge et al., 2004 )

. 

### 2 Most studies examined associations with daily 8

- h max or daytime 8

- h avg O 3 exposures, 

### 3 although associations were observed for 1

- h max ( Nickmilder et al., 2007 ) and 24

- h avg 

### 4 O 3 exposures ( Delfino et al., 2010a ) . Collectively, studies examined associations with 

### 5 single

- day O 3 exposures lagged from 0 to 5 days, and exposures averaged over 2 to 9 

### 6 days. Lag 0 of 8

- h max O 3 exposure was most frequently examined and consistently 

### 7 associated with increased airway inflammation and oxidative stress. However, in the few 

### 8 studies that examined multiple lags of exposure, multiday cumulative O 3 exposures, 

### 9 primarily based on 8

- h max or 8

- h avg, were associated with greater increases in airway 

### 10 inflammation and oxidative stress ( Berhane et al., 2011 ; Delfino et al., 2010a ; Sienra



### 11 Monge et al., 2004 ) . These findings for longer lags of exposure are supported by 

### 12 controlled human exposure studies that similarly have found that indicators of airway 

### 13 inflammation remain elevat ed following exposures to O 3 repeated over multiple days 

### 14 (Section 6.2.3.1). 

### 15 Several epidemiologic studies simultaneously examined associations of ambient O 3 

### 16 exposure with biological markers of airway inflammation and oxidative stress, lung 

### 17 function, and re spiratory symptoms. In most cases, the results differed between the 

### 18 various biomarkers and lung function. Whether evaluated at the same or different lags of 

### 19 O 3 exposure, associations generally were stronger for biological markers of airway 

### 20 inflammation tha n for lung function ( Barraza

- Villarreal et al., 2008 ; Nickmilder et al., 

### 21 2007 ) . Controlled human exposure studies also have demonstrated a lack of correlation 

### 22 between inflammatory and spirometric responses induced by O 3 exposure. Studies have 

### 23 suggested that O 3 - related respiratory morbidity may occur via multiple mech anisms with 

### 24 varying time courses of action, and the examination of a limited number of O 3 exposure 

### 25 lags in these aforementioned studies may explain some of the inconsistencies in 

### 26 associations of O 3 with different respiratory health endpoints. 

### 27 The clinical significance of changes in biological markers of airway inflammation and 

### 28 oxidative stress are not well

- characterized. However, the simultaneous examination of 

### 29 associations of O 3 with respiratory symptoms has permitted the assessment of the clinical 

### 30 signifi cance of the changes observed in biomarkers. In subjects with asthma, ambient O 3 

### 31 exposure was associated with increases in eNO and IL

- 6 that were accompanied by a 

### 32 concomitant increase in cough ( Barraza

- Villarreal et al., 2008 ) and increases in eNO and 

### 33 blood eosinophils that were accompanied by a dec rease in quality of life score ( Khatri et 

### 34 al., 2009 ) . These findings support clinically

- importa nt increases in O 3 - associated airway 

### 35 inflammation in individuals with asthma. Similar data are limited to assess the clinical 

### 36Draft

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- 79 September 2011 significance of changes in other biological markers of airway inflammation and oxidative 

### 1 stress and in other populations. 

### 2

6.2.3.3 Toxicol ogy The 2006 O 3 AQCD states that the “ extensive human clinical and animal toxicological 

### 3 evidence, together with the limited available epidemiologic evidence, is clearly indicative 

### 4 of a causal role for O 3 in inflammatory responses in the airways ” ( U.S. EPA, 2006b )

. 

### 5 Airway ciliated epithelial cells and Type 1 cells are the most O 3 - sensitive cells and are 

### 6 initial targets of O 3 . These cells are damaged by O 3 and produce a number of 

### 7 proinflammatory mediators (e.g., interleukins [IL

- 6, IL

- 8], P GE2) capable of initiating a 

### 8 cascade of events leading to PMN influx into the lung, activation of alveolar 

### 9 macrophages, inflammation, and increased permeability across the epithelial barrier. One 

### 10 critical aspect of inflammation is the potential for metapla sia and alterations in 

### 11 pulmonary morphology. Studies have observed increased thickness of the alveolar septa, 

### 12 presumably due to increased cellularity after acute exposure to O 3 . Epithelial hyperplasia 

### 13 starts early in exposure and increases in magnitude for several weeks, after which it 

### 14 plateaus until exposure ceases. When exposure persists for a month and longer, excess 

### 15 collagen and interstitial fibrosis are observed. This response, discussed in Chapter 7, 

### 16 continues to increase in magnitude throughout expos ure and can even continue to 

### 17 increase after exposure ends ( Last et al., 1984 ) . Previously published toxicological 

### 18 studies of the ability of O 3 to cause inflammation, injury, and morphological changes are 

### 19 described in Table 6

- 5 on p. 6

- 25 and Tables 6

- 10 and 6

- 11 beginning on p. 6

- 61 of the 

### 20 1996 O 3 AQCD, and Tables AX5

- 8 and AX5

- 9, beginning on p. AX5

- 17 of the 2006 O 3 

### 21 AQCD. Numerous recent in vitro and in vivo studies add to this very large body of 

### 22 evidence for O 3 - induced inflammation and injury, and provide new information regarding 

### 23 the underlying mechanisms ( Bauer et al., 2011 ; Aibo et al., 2010 ; Farraj et al., 2010 ; 

### 24 Garantziotis et al., 2010 ; Hicks et al., 2010b ; Castagna et al., 2009 ; Damera et al., 2009 ; 

### 25 Oslund et al., 2009 ; Vancza et al., 2009 ; Voynow et al., 2009 ; Fakhrzadeh et al., 2008 ; 

### 26 Han et al., 2008 ; Inoue et al., 2008 ; Oslund et al., 2008 ; Carey et al., 2007 ; Cho et al., 

### 27 2007 ; Dahl et al., 2007 ; Johnston et al., 2007 ; Kooter et al., 2007 ; Wagner et al., 2007 ; 

### 28 Wang et al., 2007 ; Yoon et al., 2007 ; Huffman et al., 2006 ; Johnston et al., 2006 ; Kenyon 

### 29 et al., 2006 ; Manzer et al., 2006 ; Plopper et al., 2 006 ; Jang et al., 2005 ; Janic et al., 2005 ; 

### 30 Johnston et al., 2005a ; Johnston et al., 2005b ; Oyarzún et al., 2005 ; Servais et al., 2005 ; 

### 31 Frush et al., In Press )

. 

### 32 A number of species, including dogs, rabbits, guinea pigs, rats, and mice have been used 

### 33 as models to study the pulmonary effects of O 3 , but the simi larity of non

- human primates 

### 34 to humans makes them an attractive model in which to study the pulmonary response to 

### 35Draft

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- 80 September 2011 O 3 . As reviewed in the 1996 and 2006 O 3 AQCDs, several pulmonary effects, including 

### 1 inflammation, changes in morphometry, and airway hyperresp onsiveness, have been 

### 2 observed in macaque and rhesus monkeys after acute exposure to O 3 (Table 6

- 17 presents 

### 3 a highlight of these studies). Increases in inflammatory cells were observed after a single 

### 4 8

- hr exposure of adult rhesus monkeys to 1 ppm O 3 ( Hyde et al., 1992 ) . Inflammation 

### 5 was linked to morphom etric changes, such as increases in necrotic cells, smooth muscle, 

### 6 fibroblasts, and nonciliated bronchiolar cells, which were observed in the trachea, 

### 7 bronchi, or respiratory bronchioles. Effects have also been observed after short

- term 

### 8 repeated exposure t o O 3 at concentrations that are more relevant to ambient O 3 levels. 

### 9 Morphometry changes in the lung, nose, and vocal cords were observed after exposure to 

### 10 0.15 ppm O 3 for 8

- h/day for 6 days ( Harkema et al., 1993 ; Dimitriadis, 1992 ; Harkema et 

### 11 al., 1987a ) . Since 2006, however, only one study has been published regarding acute 

### 12 exposure of non

- human primates to O 3 (a number of recent chronic studies in non

- human 

### 13 primates are described in Chapter 7 ). In this study, a single 6

- h exposure of adult male 

### 14 cynomolgus monkeys to 1 ppm O 3 induced significant increases in inflammatory and 

### 15 injury markers, including BAL neutrophils, total protein, alkaline phosphatase, IL

- 6, IL



### 16 8, and G

- CSF ( Hicks et al., 2010b ) . Gene expression ana lysis confirmed the increases in 

### 17 the pro

- inflammatory cytokine IL

- 8, which had been previously described in O 3 exposed 

### 18 rhesus monkeys ( Chang et al., 1998 ) . The anti

- inflammatory cytokine IL

- 10 was also 

### 19 elevated, but the fold changes in IL

- 10 and G

- CSF were relatively low and highly 

### 20 variable. The single exposure also caused necrosis and sloughing of the epithelial lining 

### 21 of the most distal portions of the terminal bronchioles and the respiratory bronchioles. 

### 22 Bronchiolitis, alveolitis, parenchymal and centriacinar inflammation w ere also observed. 

### 23 A second exposure protocol (two exposures with a 2

- week inter

- exposure interval) 

### 24 resulted in similar inflammatory responses, with the exception of total protein and 

### 25 alkaline phosphatase levels which were attenuated, indicating that atten uation of some 

### 26 but not all lavage parameters occurred upon repeated exposure of non

- human primates to 

### 27 O 3 ( Hicks et al., 2010b ) . This variability in adaptation is similar to the findings of earlier 

### 28 reports in rodents ( Wiester et al., 1996b ) and non

- human primates ( Tyler et al., 1988 )

. 

### 29 Table 6

- 17 describes morphometric studies conducted in non

- human primates exposed 

### 30 to O 3 . 

### 31Draft

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- 81 September 2011 

### Table 6 - 17 Morphometric observations in non - human primates after acute O 3 

### exposure
Reference O 3 concentration Exposure duration Species, Sex, Age Observation Harkema et al. ( 1993 ) 0.15 8 h/ day for 6 d ays Macaca radiata Several fold increase in thickness of surface epithelium in respiratory bronchioles Harkema et al. ( 1987a ; 1987b ) Dimitriadis ( 1992 ) 0.15 0.3 8 h/ day for 6 d ays 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 Leonard et al. ( 1991 ) 0.25 8 h/d ay for 7 d ays Macaca radiata 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 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 Hicks et al. ( 2010a ) 1.0 6 h Cynomolgus, M 5
- 7 kg Increase in PMNs and IL
- 8 in lavage fluid

Confirmation of pulmonary changes observed in non

- human primates, at near ambient 

### 1 O 3 concentrations, has been done in a large number of studies in guinea pigs and rodents 

### 2 (see 1996 and 2006 O 3 AQCDs) ( U.S. EPA, 2006b , 1996a ) . Mechanistic studies 

### 3 completed more recently have extended these findings. Exposure of adult BALB/c mice 

### 4 to 0.1 ppm O 3 for 4 hours increased BAL levels of keratinocyte chemoattractant (KC; IL



### 5 8 homologue) (~ sixfold), IL

- 6 (~12

- fold), and TNF

- α (~ twofold) ( Damera et al., 2010 )

. 

### 6 Additionally, O 3 increased BAL neutrophils by 21% with out changes in other cell types. 

### 7 A trend of increased neutrophils with increased O 3 concentration (0.12

- 2 ppm) was 

### 8 observed in BALB/c mice exposed for 3 hours ( Jang et al., 2005 ) . Although alterations in 

### 9 the epithelium of the airways were not evident in 129J mice after 4 hours of exposure to 

### 10 0.2 ppm O 3 ( Plopper et al., 2006 ) , detachment of the bronchiolar epithelium was 

### 11 observed in SD rats after 5 days or 60 days of exposure to 0.25 ppm O 3 ( Oyarzún et al., 

### 12 2005 ) . Subacute (65 hours) exposure to 0.3 ppm O 3 induced pulmonary inflammation, 

### 13 cytokine induction, and enhanced vascular permeabili ty in wild type mice of a mixed 

### 14 background (129/Ola and C57BL/6) and these effects were exacerbated in 

### 15 metallothionein I/II knockout mice ( Inoue et al., 2008 ) . Three hours or 72 hours of 

### 16 exposure to 0.3 ppm O 3 resulted in similar levels of IL

- 6 expression in the lungs of 

### 17 C57BL/6 mice ( Johnston et al., 2005b ) , along with increases in BAL protein, sTNFR1, 

### 18 and sTNFR2. Increased neutrophils were observed only after the 72

- h exposure, and 

### 19 neither exposure resulted in detectable levels of IL

- 6 or KC protein. Levels of BAL 

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- 82 September 2011 protein, sTNFR1, and sTNFR2 were higher in the 72

- h exposure group than in the 3

- h 

### 1 exposure group. In another study, the same subacute (72 hours) exposure protocol elicited 

### 2 increases in BALF protein, IP

- 10, sTNFR1, macrophages, neutrophils, and IL

- 6, IL

- 1α, 

### 3 and IL

- 1β expression ( Johnston et al., 2007 ) . Yoon et al. ( 2007 ) exposed C57BL/6J mice 

### 4 continuously to 0.3 ppm O 3 for 6, 24, 48, or 72 hours, and observed elevated levels of 

### 5 KC, MIP

- 2, metalloproteinases, and inflammatory cells in the lungs at various time 

### 6 points. A similar exposure protocol using C3H/HeJ and C3H/OuJ mice demonstrated 

### 7 elevations in protein, PMNs, and KC, which were predominantly TLR 4 pathway 

### 8 dependent based on their prominence in the TLR 4 sufficient C3H/OuJ strain ( Bauer et 

### 9 al., 2011 ) . C3H/OuJ mice also had elevated levels of the heat

- shock protein HSP70, and 

### 10 further experiments in HSP70 deficient mice indicated a role for this parti cular pathway 

### 11 in O 3 - related injury, discussed in more detail in Chapter 5. 

### 12 As reviewed in the 2006 O 3 AQCD, the time course for changes in BAL depends on the 

### 13 parameters being studied. Similarly, after exposing adult C57BL mice to 0.5 ppm O 3 for 

### 14 3 hours, Ha n et al. ( 2008 ) observed early (5 hours postexposure) increases in BAL TNF

- α 

### 15 and IL

- 1β, which diminished by 24 hours postexposu re. Total BAL protein was elevated 

### 16 at 24 hours, but there were only minimal or negligible changes in LDH, total cells, or 

### 17 PMNs. Ozone increased BAL mucin levels (with statistical significance by 24 hours 

### 18 postexposure), and significantly elevated surfactant protein D at both time points. Prior 

### 19 intratracheal (IT) exposure to multiwall carbon nanotubes enhanced most of these effects, 

### 20 but the majority of responses to the combined exposure were not greater than those to 

### 21 nanotubes alone. Ozone exposure did not in duce markers of oxidative stress in lung 

### 22 tissue, BAL, or serum. Consistent with this study, Aibo et al. ( 2010 ) did not detect 

### 23 changes in BAL inflammatory cell numbers in the same mouse strain after a 6

- h exposure 

### 24 to 0.25 or 0.5 ppm. The majority of inflammatory cyto kines (pulmonary or circulating) 

### 25 were not significantly changed (as assessed 9 hours post O 3 exposure). 

### 26 Animal toxicology studies have also examined susceptibility factors and the findings 

### 27 complement research in both controlled human exposure and epidemiol ogic studies. In a 

### 28 study examining age, strain, and gender as factors for susceptibility to O 3 in mice, 

### 29 increased BAL neutrophils were observed in all 8 strains of neonates and adults but 

### 30 statistical significance was found in only 4 strains of neonates and 2 strains of adults at 

### 31 24 hours after exposure to 0.8 ppm O 3 for 5 hours ( Vancza et al., 2009 ) . Lung injury, as 

### 32 measured by BAL protein, was significantly increased in 5 and 8 strains of neonates and 

### 33 adults, respectively. Interestingly, the observed age

- dependent differences in response to 

### 34 O 3 occurred in only certain strains. For example, the fold

- increase in neutrophils was 

### 35 significantly higher, in neonates compared to adults, in the SJL and C3H/HeJ strains and 

### 36 lower in BALB/c mice. Measurement of 18 O determined that the observed strain

- and 

### 37 age - dependent differences were not due to absorbed O 3 dose. Subanalysis of the adult 

### 38Draft

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- 83 September 2011 mice demonstrated that gender also played a small, but statistically significant, role in the 

### 1 effect of O 3 on BAL neutrophils and protein. These findings suggest that the response to 

### 2 O 3 , in mice, may consist of a complex interaction of age, gender, and genetic factors. 

### 3 A study assessing NQO1 as a susceptibility factor was conducted by Voynow et al. 

### 4 ( 2009 ) . Specific effects of this gene on O 3 responses are discussed in Chapter 8; only 

### 5 ozone ’ s effects in wild type C57BL/6 mice are descr ibed here. Exposure to 1 ppm for 

### 6 3 hours increased BAL total cells, neutrophils, and KC; these responses were greatest at 

### 7 24 hours postexposure. F2

- isoprostane (8

- isoprostane), a marker of oxidative stress, was 

### 8 also elevated by O 3 , peaking at 48 hours post exposure. 

### 9 Atopic asthma appears to be a risk factor for more severe O 3 induced airway 

### 10 inflammation in humans ( Balmes et al., 1997 ; Scannell et al., 1996 ) , and allergic animal 

### 11 models are often used to investigate the effects of O 3 on this susceptible population. 

### 12 Farraj et al. ( 2010 ) exposed allergen

- sensitized adult male BALB/c mice to 0.5 ppm O 3 

### 13 for 5 hours once per week for 4 weeks. Ovalbumin

- sens itized mice exposed to O 3 had 

### 14 significantly increased BAL eosinophils by 85% and neutrophils by 103% relative to 

### 15 OVA sensitized mice exposed to air, but these changes were not evident upon 

### 16 histopathological evaluation of the lung, and no O 3 induced lesions were evident in the 

### 17 nasal passages. Ozone increased BAL levels of N

- acetyl

- glucosaminidase (NAG; a 

### 18 marker of injury) and protein. DEP co

- exposure (2.0 mg/m 3 , nose only) inhibited these 

### 19 responses. These pro

- inflammatory effects in an allergic mouse model h ave also been 

### 20 observed in rats. Wagner et al. ( 2007 ) exposed the relatively O 3 - resistant Brown Norway 

### 21 rat strain to 1 ppm O 3 after sensitizing and challenging with OVA. Rats were exposed for 

### 22 2 days, and airway inflammation was assessed one day later. Filtered air for controls 

### 23 contained less than 0.02 ppm O 3 . Histopathology indicated O 3 induced site

- specific lung 

### 24 lesions in the centriacinar regions, characterized by wall thickening partly due to 

### 25 inflammatory cells influx. BAL neutrophils were elevated by O 3 in allergic rats, and 

### 26 modestly increased in non

- allergic animals (not significant). A slight (but not significant) 

### 27 increase in macrophages was observed, but eosinophil numbers were not affected by O 3 . 

### 28 Soluble mediators of inflammation (Cys

- LT, MCP

- 1, and IL

- 6) were elevated by O 3 in 

### 29 allergic animals but not non

- allergic rats. Treatment with γT, which neutralizes oxidized 

### 30 lipid radicals and protects lipids and proteins from nitrosative damage, did not alter the 

### 31 morphologic character or severity of the centriacinar lesions caused by O 3 , nor did it 

### 32 reduce neutrophil influx. It did, however, significantly reduce O 3 - induced soluble 

### 33 i nflammatory mediators in allergic rats. The effects of O 3 in animal models of allergic 

### 34 asthma are discussed in section 6.2.6. 

### 35 In summary, a large number of toxicology studies have demonstrated that acute exposure 

### 36 to O 3 produces injury and inflammation in the mammalian lung, supporting the 

### 37Draft

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- 84 September 2011 observations in controlled human exposure studies (Section 6.2.3.1). These acute 

### 1 changes, both in inflammation and morphology, provide a modicum of evidence for long 

### 2 term sequelae of exposure to O 3 . Related alterations re sulting from long term exposure, 

### 3 such as fibrotic changes, are discussed in Chapter 7. 

### 4
Mechanisms of Injury Since O 3 has been well established as a causative agent of airway inflammation and 

### 5 injury, which may contribute to functional changes observed in hu man subjects, the 

### 6 majority of recent research has focused on the underlying mechanisms. A brief 

### 7 description of some of the recent contributions to this area of research is provided here; 

### 8 more detailed descriptions of the mechanisms behind O 3 - mediated injur y and 

### 9 inflammation can be found in the mode of action chapter (Chapter 5). There are several 

### 10 signaling pathways responsive to changes in oxidation status, which tend to be influenced 

### 11 at different levels in different host backgrounds. The molecular mechanis ms of TNF 

### 12 receptor

- mediated lung injury induced by O 3 and associated signaling pathways (NF

- κB, 

### 13 MAPK/AP

- 1) have been examined ( Fakhrzadeh et al., 2008 ; Cho et al., 2007 ) , along with 

### 14 the changes in gene expression which characterize O 3 - induced stress and inflammation 

### 15 ( Wang et al., 2007 ) . Other contributors to injury and inflammation include the IL

- 1 and 

### 16 neurokinin receptors ( Oslund et al., 2008 ; Johnston et al., 2007 ) , calcitonin gene

- related 

### 17 peptide receptor activation ( Oslund et al., 2009 ) , CXCR2, a receptor for neutrophil 

### 18 chemokines ( Johnston et al., 2005a ) , mindin, an extracellular matrix protein ( Frush et al., 

### 19 In Press ) , and NQO1 ( Voynow et al., 2009 ) , an enzyme involved in oxidative stress. 

### 20 Studies indicate a role for oxidative stress in mediating inflammation ( Wagner et al., 

### 21 2007 ; Jang et al., 2005 ) . Protective roles have been identified for nitric oxide synthase 

### 22 ( Kenyon et al., 2006 ) , metallothionein ( Inoue et al., 2008 ) , matrix metalloproteinases 

### 23 ( Yoon et al., 2007 ) , Clara cell secretory protein ( Plopper et al., 2006 ) , and the recogn ition 

### 24 of oxidized lipids by alveolar macrophages ( Dahl et al., 2007 )

. 

### 25

6.2.4 Respiratory Symptoms and Medication Use Controlled human exposure and toxicological studies have described the modes of action 

### 26 through which short

- term O 3 ex posure may lead to increases in respiratory symptoms by 

### 27 demonstrating O 3 - induced increases in airway hyperresponsiveness, bronchoconstriction 

### 28 (Section 6.2.2), and pulmonary inflammation (Sections 6.2.3.1 and 6.2.3.3). While 

### 29 epidemiologic studies have not w idely examined associations between ambient O 3 

### 30 exposure and airway hyperresponsiveness, they have found O 3 - associated increases in 

### 31 pulmonary inflammation and oxidative stress (Section 6.3.2.2). In addition to decreases 

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- 85 September 2011 in lung function, controlled human ex posure studies clearly demonstrate increases in 

### 1 subjective respiratory symptoms including cough, pain on deep inspiration, and shortness 

### 2 of breath (described in detail in Section 6.2.1.1). Similar to lung function responses, these 

### 3 respiratory symptoms incr ease with exposure concentration, activity level of the exposed 

### 4 individual, and duration of exposure ( McDonnell et al., 1999 ) . Increases in subjective 

### 5 respiratory symptoms have been reported following 5.6 and 6.6 h of exposure to 60 ppb 

### 6 O 3 . However, the severity of respiratory symptoms following 6.6 h of exposure to 80 ppb 

### 7 O 3 during moderate exercise is roughly 2

- 3 times greater than that at 60 ppb O 3 ( Adams, 

### 8 2006a ) . These fin dings integrated across disciplines provide biological plausibility for 

### 9 epidemiologic associations between increases in short

- term ambient O 3 exposure and 

### 10 increases in respiratory symptoms. 

### 11 In epidemiologic studies, respiratory symptom data typically are collected by having 

### 12 subjects or their parents record symptoms such as wheeze, cough, and shortness of breath 

### 13 and medication use in a diary without direct supervision by study staff. Several 

### 14 limitations of symptom reports are well

- recognized: recall error i f not recorded daily, 

### 15 differences among subjects in the interpretation of symptoms, biased reporting between 

### 16 participants with and without asthma, and occurrence in a smaller percentage of the 

### 17 population compared with changes in lung function and biologica l markers of pulmonary 

### 18 inflammation. Nonetheless, symptom diaries remain a convenient and useful tool to 

### 19 collect individual

- level data from a large number of subjects and allow the modeling of 

### 20 associations between daily changes in O 3 exposure and daily cha nges in respiratory 

### 21 morbidity. Importantly, most of the limitations described above are sources of random 

### 22 measurement error that can bias effect estimates to the null or increase the uncertainty 

### 23 around effect estimates. Furthermore, because respiratory sym ptoms are associated with 

### 24 limitations in activity and function and are the primary reason for using medication and 

### 25 seeking medical care, they provide an assessment of the clinical and public health 

### 26 significance of ambient O 3 exposure. 

### 27 Most studies have be en conducted in individuals with asthma, and as was concluded in 

### 28 previous O 3 AQCD, the collective body of epidemiologic evidence strongly supports 

### 29 associations between increases in short

- term ambient O 3 exposure and increases in 

### 30 respiratory symptoms in chi ldren with asthma ( U.S. EPA, 2006b , 1996a ) (Figure 6

- 11 

### 31 and Table 6

- 19). Evidence also indicates that O 3 exposure likely is associated with 

### 32 increased use of asthma medication (Figure 6

- 12 and Table 6

- 20). Studies also find O 3 

### 33 exp osure to be associated with respiratory symptoms in adults with asthma. The effects of 

### 34 O 3 exposure on respiratory symptoms in healthy populations are not as clearly indicated 

### 35 (Figure 6

- 13 and Table 6

- 23) 

### 36Draft

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- 86 September 2011 

### 6.2.4.1 Children with Asthma Respiratory Symptoms Table 6

- 18 presents the characteristics and ambient O 3 concentration data from studies 

### 1 assessing associations of short

- term O 3 exposure with respiratory symptoms and 

### 2 medication use in children with asthma. The strong evidence for associations between 

### 3 ambient O 3 expo sure and respiratory symptoms among children with asthma is derived 

### 4 mostly from several single

- region or single

- city studies (Figure 6

- 11 and Table 6

- 19). 

### 5 Most studies of children with asthma examined 1

- h max, 8

- h max, or 8

- h average O 3 

### 6 exposures. In U.S. multicity studies, O 3 was associated with both increases and decreases 

### 7 in respiratory symptoms among children with asthma ( O'Connor et al., 2008 ; Schildcrou t 

### 8 et al., 2006 ; Mortimer et al., 2002 ) . In the NCICAS cohort (described in Section 6.2.1.2), 

### 9 a 30

- ppb increase in lag 1

- 4 avg of 8

- h avg (10:00 a.m.

- 6:00 p.m.) O 3 was associated with 

### 10 an increase in morning asthma symptoms with an OR (95% CI) of 1.35 (95% CI: 1.04, 

### 11 1.69) ( Mortimer et al., 2002 ) . This association did not change (OR: 1.37 [95% CI: 1.02, 

### 12 1.84]) in an analysis restricted to O 3 concentrations below 80 ppb. Odds ratios for lags 2 

### 13 and 4 of O 3 exposure were similar in magntiude. In the ICAS cohort (described in Section 

### 14 6.2.1.2), associations of 19

- day avg of 24

- h avg O 3 with wheeze and nighttime asthma 

### 15 were positive and negative, respectively ( O'Connor et al., 2008 ) . NCICAS was conducted 

### 16 during the warm season, and symptom data were collected daily ( Mortimer et al., 2002 ; 

### 17 Mortimer et al., 2000 ) , whereas in ICAS, every 2 months, parents reported the number of 

### 18 days with respiratory symptoms over the previous 2 weeks ( O'Connor et al., 2008 )

. 

### 19 Because of the two

- week symptom reporting period, ICAS investigators were precluded 

### 20 from examining associatio ns with single

- day and shorter

- duration O 3 exposure periods. 

### 21 Evidence of O 3 - associated respiratory symptoms also was weak in another recent U.S. 

### 22 multicity study (with cities in common with NCICAS and ICAS, Table 6

- 18) of 990 

### 23 children with asthma ( Schildcrout et al., 2006 ) . As part of the Childhood Asthma 

### 24 Management Program, symptom data were collected daily, and analyses were restricted 

### 25 to peak O 3 periods between May and September. In meta

- analyses that combined city



### 26 specific estimates, a 40

- ppb increase in lag 0 of 1

- h m ax O 3 was associated with any 

### 27 asthma symptom with an OR (95% CI) of 1.08 (0.89, 1.31). Odds ratios for lags 1 and 2 

### 28 and the 3

- day sum of O 3 were near 1.0. In this study, data were available from an average 

### 29 of 12 subjects per day per city, and fewer data we re collected in summer months. 

### 30 Because O 3 analyses were restricted to summer months, the fewer number of 

### 31 observations reduced the power to detect associations for O 3 relative to other pollutants, 

### 32 which were analyzed using year

- round data. 

### 33Draft

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- 87 September 2011 

### Table 6 - 18 Mean and upper percentile ozone concentrations in epidemiologic studies examining respiratory symptoms, medication use, and activity levels in children with asthma Study Location Years/Season O 3 Averaging Time Mean /Median Concentration (ppb) Upper Percentile Concentrations (ppb) Mortimer et al. ( 2000 ) Mortimer et al. ( 2002 ) Bronx, East Harlem, NY; Baltimore, MD; Washington, DC; Detroit, MI, Cleveland, OH; Chicago, IL; St. Louis, MO (NCICAS) 1993 Warm season 8
- h avg (10:00 a.m.
- 6:00 p.m.) 48 NR

O ’ Connor et al. ( 2008 ) Boston, MA; Bronx, Manhattan NY; Chicago, IL; Dallas, TX, Seattle, WA; Tucson, AZ (I CAS) 1998
- 2001 All
- year 24
- h avg NR NR

Schildcrout et al. ( 2006 ) Albuquerque, NM; Baltimore, MD; Boston, MA; Denver, CO; San Diego, CA; Seattle, WA; St. Louis, MO; Toronto, ON, Canada (CAMP) 1994
- 1995 Warm season 1
- h max Range in medians across cities: 43.0
- 65.8 Ra nge in 90th across cities: 61.5
- 94.7
Gent et al. ( 2003 ) CT, southern MA 2001 April
- September 1
- h max 8
- h rolling avg 58.6 51.3 Max: 125.5 Max: 99.6
Thurston et al. ( 1997 ) Connecticut River Valley, CT 1991
- 1993 Warm season 1
- h max 83.6 Max: 160
Rabinovitch et al. ( 2004 ) Denver, CO 1999
- 2002 Cold season 1
- h max 28.2 Max: 70.0
Mann et al. ( 2010 ) Fresno/Clovia, California 20 00
- 2005 All
- year 8
- h max 49.4 (median) 75th: 69.5, Max: 120.0 Ostro et al. ( 2001 ) Los Angeles, CA 1993 August
- October 1
- h max Los Angeles: 59.5 Pasadena: 95.8 Max: 130 Max: 220 Delfino et al. ( 2003 ) Los Angeles, CA 1999
- 2000 Cold season 1
- h max 8
- h max 25.4 17.1 90th: 38.0, Max: 52 90th: 26.1, Max: 37 Romieu et al. ( 1996 ) norther n Mexico City, Mexico April
- July 1991 November 1991
- February 1992 1
- h max 190 Max: 370

Romieu et al. ( 1997 ) southern Mexico City, Mexico April
- July 1991 November 1991
- February 1992 1
- h max 196 Max: 390

Romieu et al. ( 2006 ) Mexico City, Mexico 1998
- 2000 All
- year 1
- h max 8
- h max 102 69 Max: 309 Max: 184 Escamilla
- Nunez et al. ( 2008 ) Mexico City, Mexico 2003
- 2005 All
- year 1
- h max 8
- h max 86.5 31.6 Max: 86.3 (8
- h max) Gielen et al. ( 1997 ) Amsterdam, Netherlands 1995 Warm season 8
- h max 34.2 Max: 56.5
Just et al. ( 2002 ) Paris, France 1996 April
- June 24
- h avg 30.0 Max: 61.7 Jalaludin et al. ( 2004 ) Sydney, Australia 1994 All
- year 15
- h avg (6:00 a.m. - 9:00 p.m.) 12 Max: 43

NCICAS = National Cooperative Inner
- City Asthma Study, NR = Not Reported, ICAS = Inner City Asthma Study, NR = Not Reported, CAMP = Childhood Asthma Management Program, Max = Maximum.Draft

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- 88 September 2011 

### Figure 6 - 11 Associations of ambient ozone exposure with respiratory symptoms in children with a s thma. Results are presented first for aggregate indices of symptoms then for individual symptoms. Within each category, results generally are organized in order of increasing mean ambient O 3 

### concentration. LRS = lower respiratory symptoms, URS = upper respiratory symptoms. Effect estimates 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, and 15 - h avg or 24 - h avg ozone ex posures, respectively. 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 Wheeze Cough Wheeze Chest symptoms Difficulty breathing O 3 Lag

0
- 2 avg 0 0 0

1
- 4 avg

0 0

2 1
- 19 avg 3 0 0
0 0
- 5 avg Subgroup

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 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
- 89 September 2011 

### Table 6 - 19 Additional characteristics and quantitative data for studies presented in Figure 6 - 1 1
Study Location/ Population O 3 Lag O 3 Averagin

g Time Symptom Subgroup Odds Ratio (95% CI) a Studies examining aggregates of symptoms Rabinovitch et al. ( 2004 ) Denver, CO Children with asthma 0
- 2 avg 1
- h max Daytime symptoms 1.34 (1.01, 1.77) Delfino et al. ( 2003 ) Los Angeles, CA Children with asthma 0 1
- h max Bothersome symptoms 1.09 (0.39, 3.03) Schildcrout et al. ( 2006 ) 8 U.S. communities Children with asthma 0 1
- h max Asthma symptoms 1.08 (0.89, 1.31) Gielen et al. ( 1997 ) Amsterdam, Netherlands Children with asthma 0 8
- h max LRS URS 1.04 (0.75, 1.45) 1.16 (1.02, 1.32) Mortimer et al. ( 2002 ) Mortimer et al. ( 2000 ) 8 U.S. communities Children with asthma 1
- 4 avg 8
- h avg (10:00 a.m.
- 6:00 p.m.) Morning symptoms All subjects No medication use Cromolyn use β
- agonist/xanthine use Steroid use Without allergy With allergy 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 Children with asthma 0 1
- h max LRS 1.07 (1.02, 1.12)

Romieu et al

. ( 1997 ) southern Mexico City, Mexico Children with asthma 0 1
- h max LRS 1.09 (1.04, 1.14) Studies examining individual symptoms Jalaludin et al. ( 2004 ) Sydney, Australia Children with asthma 2 15
- h avg (6:00 a.m.
- 9:00 p.m.) Wheeze 1.21 (0.92, 1.59)
O ’ Connor et al. ( 2008 ) 7 U.S. communities Children with asthma 1
- 19 avg 24
- h avg Wheeze/cough 1.02 (0.86 , 1.21)

Ostro et al. ( 20 01 ) Los Angeles, CA Children with asthma 3 1
- h max Wheeze 0.94 (0.88, 1.00)
Escamilla
- Nunez et al. ( 2008 ) Mexico City, Mexico Children with asthma 0 1
- h max Wheeze 1.08 (1.03, 1.14)
Mann et al. ( 2010 ) Fresno/Clovia, California Children with asthma 0 8
- h max Wheeze All Fungi allergic 1.00 (0.84, 1.19) 1.06 (0.84, 1.34) Thurston et al. ( 1997 ) CT River Valley, CT Children with asthma 0 1
- h max Chest symptoms 1.28 (1.10, 1.50)
Romieu et al. ( 2006 ) Mexico City, Mexico Children with asthma 0
- 5 avg 1
- h max Difficulty breathing GSTM1 sufficient GSTM1 null GSTP1 Ile/Ile 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) 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, and 15
- h avg or 24
- h avg O 3 , respectively. 

### 1 Several longitudinal studies conducted in multiple cohorts of children with asthma in 

### 2 Mexico City, Mexico examined 1

- h max O 3 exposures and found associations with 

### 3 increases in respiratory symptoms ( Escamilla

- Nuñez et al., 2008 ; Romieu et al., 2006 ; 

### 4 Romieu et al., 1997 ; Romieu et al., 1996 ) . Recent studies expanded on earlier evidence 

### 5Draft

– Do Not Cite or Quote 6
- 90 September 2011 by indica ting associations with multiday averages of O 3 exposure. Both Romieu et al. 

### 1 ( 1996 ) and Romieu et al. ( 1997 ) found that among single

- day 1

- h max O 3 exposures 

### 2 lagged 0 to 2 days, lag 0 had the greatest estimated effect on respiratory symptoms. 

### 3 Romieu et al. ( 2006 ) and Escamilla

- Nunez et al. ( 2008 ) found that the magnitudes of 

### 4 association of ambient 1

- h max O 3 exposure w ith respiratory symptoms and medication 

### 5 use increased with increasing number of days over which O 3 exposure was averaged. 

### 6 Studies of children with asthma also identified factors that may contribute to 

### 7 heterogeneity in symptom responses to ambient O 3 expos ure. Multiple studies, all of 

### 8 which examined 8

- h avg (10:00 a.m.

- 6:00 p.m.) or 8

- h max O 3 exposures, found larger 

### 9 associations among subjects taking asthma medication; however, the medications varied 

### 10 among studies. Consistent with findings for lung functio n, in the NCICAS multicity 

### 11 cohort, larger associations for morning symptoms were observed in children taking 

### 12 cromolyn (used to treat asthma with allergy) or beta

- agonists/xanthines than in children 

### 13 taking no medication. Odds ratios did not differ as much b etween children taking steroids 

### 14 and children taking no medication (Figure 6

- 11 and Table 6

- 19) ( Mortimer et al., 2000 )

. 

### 15 In a cohort of children with asthma in Southern New England, O 3 exposures were 

### 16 associated with larger increases in chest tightness among children taking maintenance 

### 17 medication (i.e., steroids, cromolyn, or leukotriene inhibitors). 

### 18 Most studies of children with asthma reported that a majority of subjects (52 to 100%) 

### 19 were atopic as determined by a positive skin prick test to any examined allergen; 

### 20 however, results did not conclusively indicate that children with asthma and atopy were 

### 21 more susceptible to the effects of O 3 exposure. In the multicity NCICAS cohort, 

### 22 Mortimer et al. ( 2000 ) found that O 3 was associated with a similar incidence of asthma 

### 23 symptoms among the 79% of subjects with atopy and the 21% of subjects without atopy 

### 24 (Figure 6

- 11 and Table 6

- 19). Odds ratios did not differ by residential levels of allergens. 

### 25 In a recent study of childre n with asthma in Fresno, CA, most associations of single

- and 

### 26 multiday lags of 8

- h max O 3 exposure (0

- 14 days) with wheeze were near or below 1.0 

### 27 ( Mann et a l., 2010 ) . The estimated effects did not differ in fungi allergic subjects, A 

### 28 larger association was found for cat allergic subjects; however, this finding was limited to 

### 29 O 3 exposure lagged 14 days. In this study, many subjects were allergic to multiple 

### 30 allergens; however, associations were not compared between subjects with any versus no 

### 31 allergic sensitization. 

### 32 Although Romieu et al. ( 2006 ) did not observe differences in associat ions between O 3 

### 33 and lung function by GST genetic polymorphisms (Section 6.2.1.2), they did observe 

### 34 effect modification for respiratory symptoms. Compared with GSTM1 positive subjects 

### 35 and GSTP1 Ile/Ile or Ile/Val subjects, larger effects were estimated for GSTM1 null 

### 36 subjects and for GSTP1 Val/Val subjects, respectively (Figure 6

- 11 and Table 6

- 19). 

### 37Draft

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- 91 September 2011 Ozone had the greatest estimated effect on difficulty breathing in children with asthma 

### 1 who were both GSTM1 null and GSTP1 Val/Val (OR: 1.49 [95% CI: 1.14, 1.93] per 30

- 

### 2 ppb increase in lag 0

- 5 avg of 8

- h max O 3 ). In the same cohort of children, antioxidant 

### 3 supplementation reduced O 3 - associated increases in airway inflammation ( Sienra

- Monge 

### 4 et al., 2004 ) . These results add to the body of epidemiologic evidence that antioxidant 

### 5 capacity influences risk of O 3 - related respiratory morbidity. As was discussed in Section 

### 6 6.2.1.2, compared with the GSTM1 genotype, evidence for effect modification by GSTP1 

### 7 genetic polymorphisms is less certain. Romieu et al. ( 2006 ) found that the GSTP1 

### 8 Val/Val variant was associated with a lesser O 3 - associated decrement in lung function but 

### 9 greater risk of respiratory symptoms. Whereas some studies have reported greater risk of 

### 10 as thma among GSTP1 Ile/Ile or Ile/Val subjects ( Mapp et al., 2002 ; Hemmingsen et al., 

### 11 2001 ) , others have reported greater risk among GSTP1 Val/Val subjects ( Tamer et al., 

### 12 2004 ) . In Romieu et al. ( 2006 ) , GSTP1 Ile/Ile was associated with greater severity of 

### 13 asthma, and Lee et al. ( 2004b ) also reported greater risk of air pollution

- associated 

### 14 asthma among GSTP1 Ile/I le children in the Southern California Children ’ s Health 

### 15 Study. 

### 16

Asthma Medication Use The 2006 O 3 AQCD concluded that ambient O 3 likely was associated with increased 

### 17 asthma medication use based on the positive associations found in several studies of 

### 18 child ren with asthma (Figure 6

- 12 and Table 6

- 20). Among the few newly available 

### 19 studies on asthma medication use, evidence generally supported the previous conclusion 

### 20 ( Escamilla

- Nuñez et al., 2008 ; Romieu et al., 2006 ) . Most of these studies examined lags 

### 21 0 or 1 of 1

- h max O 3 expos ures; however, Romieu et al. ( 2006 ) found that lag 0

- 5 avg of 

### 22 1

- h max O 3 was associated with a larger increase in bronchodilator use than were lags 1 

### 23 or 0

- 1 avg. As compared with respiratory symptoms, effects on medication use were 

### 24 estimated with greater uncertainty as indicated by the wide 95% CIs. The wide 95% CIs 

### 25 have been attributed to a smaller number of study subjects reporting medication use and 

### 26 the low frequency of use over the study period. However, within most studies, findings 

### 27 were similar for respiratory symptoms and asthma medication use. Among recent studies, 

### 28 Romi eu et al. ( 2006 ) and Escamilla

- Nunez et al. ( 2008 ) observed O 3 - associated increases 

### 29 in both respiratory symptoms and bronchodilator use. Schildcrout et al. ( 2006 ) did not 

### 30 observe O 3 - associated increases in either respiratory symptoms or rescue inhaler use. In 

### 31 contrast, Romieu et al. ( 1996 ) and Rabinovitch et al. ( 2004 ) observed that O 3 was 

### 32 positively associated with daytime respiratory symptoms but not with bronchodilator use. 

### 33Draft

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- 92 September 2011 CS = corticosteroid. Results are presented in increasing order of ambient ozone co ncentration. Effect estimates are from single
pollutant models and are standardized to a 40
- and 30
- ppb increase for 1
- h max and 8
- h max ozone, respectively 

### Figure 6 - 12 Associations of ambient ozone exposure with asthma medication use.

Table 6 - 20 Additiona l characteristics and quantitative data for studies presented in Figure 6 - 12
Study Location/ Population O 3 Lag O 3 Averaging

Time Medication Subgroup Odds Ratio (95% CI) a Schildcrout et al. ( 2006 ) 8 U.S. communities Children with asthma 0 1
- h max Rescue inhaler use 1.01 (0.89, 1.15)
Thurston et al. ( 1997 ) CT River Valley, CT Asthmatic campers 0 1
- h max Beta
- agonist use 1.17 (0.96, 1.44) Ostro et al. ( 2001 ) Los Angeles, CA Children with asthma 1 1
- h max Extra medication use 1.10 (1.03, 1.19)
Romieu et al. ( 1996 ) northern Mexico City, Mexico Children with asthma 0 1
- h max Bronchodilator use 0.97 (0.93, 1.01)
Romieu et al. ( 1997 ) southern Mexico City, Mexico Children with asthma 0 1
- h max Bronchodilator use 1.02 (1.00, 1.05)
Romieu et al. ( 2006 ) Mexico City, Mexico Children with asthma 0
- 5 avg 1
- h max Bronchodilator use GSTP1 Ile/Ile Ile/Val GSTP1 Val/Val 0.96 (0.90, 1.02) 1.10 (1.02, 1.19) Gielen et al. ( 1997 ) Amsterdam, Netherlands Children with asthma 0 8
- h max Bronchodilator use 1.10 (0.78, 1.55)
Jalaludin et al. ( 20 04 ) Sydney, Australia Children with asthma 1 1
- h max Beta
- agonist use/no steroid ICS use 1.08 (0.89, 1.32) 1.08 (0.96, 1.21) CS= Corticosteroid. a Effect estimates are standardized to a 40
- and 30
- ppb increase for 1
- h max and 8
- h max O 3 , respectively. 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) Outcome Rescue inhaler use Beta
- agonist use Extra medication use Bronchodilator use Bronchodilator use Bronchodilator use

Bronchodilator use Beta
- agonist use/no steroid CS use Lag 0 0 1 0 0 0
- 5 avg

0 1 Subgroup

GSTP1 Ile/Ile Ile/Val GSTP1 Val/Val

0 0.5 1 1.5 2 Odds ratio (95% CI)Draft

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- 93 September 2011 Changes in Activity While investigation has been limited, evidence has not consistently indicated associations 

### 1 between O 3 exposure and diminished activity level in children with asthma ( O'Connor et 

### 2 al., 2008 ; Delfino et al., 2003 ) . These studies have examined a range of O 3 averaging 

### 3 times and lags of exposure. In the large ICAS cohort, O ’ Connor et al. ( O'Connor et al., 

### 4 2008 ) found that a 20

- ppb increase in lag 1

- 19 avg of 24

- h O 3 ambeint was associated 

### 5 with a 10% lower odds (95% CI:

- 26, 10) of slow play. In a small ( n = 22) panel study 

### 6 conducted in children with asthma in Los Angeles CA, Delfino et al. ( 2003 ) found that a 

### 7 40

- ppb increase in lag 0 of 1

- h max O 3 was associated with an increase in symptoms that 

### 8 interfered with daily activity with an OR (95% CI) of 7.41 (1.18, 43.2). Sever al studies 

### 9 reported increases in school absenteeism in children with asthma in association with long 

### 10 lags of O 3 exposure (14

- day and 30

- day distributed lags or 19

- day avg) ( O'Connor et al., 

### 11 2008 ; Gilliland et al., 2001 ; Chen et al., 2000 ) . Whereas Chen et al. ( 2000 ) and O ’ Connor 

### 12 et al. ( 2008 ) examined absences for any reason, Gilliland et al. ( 2001 ) found associations 

### 13 with absences for respiratory illnesses. D espite this evidence, several limitations have 

### 14 been noted, including the uncertain biological relevance of long lag periods of O 3 

### 15 exposure and the potential for residual seasonal confounding when examining long lag 

### 16 periods of exposure. In analyses of singl e - day lags, Gilliland et al. ( 2001 ) found that 8

- h 

### 17 avg (10:00 a.m.

- 6:00 p.m.) O 3 exposure was associated with increases in respiratory



### 18 related absences from lag day 1 to lag day 5, indicating an effect of exposures with 

### 19 shorter lag periods. 

### 20

6.2.4.2 Adults with Respiratory Disease
Characteristics and ambient O 3 concentration data from studies of adults with respiratory 

### 21 disease are p resented in Table 6

- 21. In this relatively small body of literature, several 

### 22 studies found ambient O 3 exposure (1

- h max or 8

- h max) to be associated with increases 

### 23 respiratory symptoms and decreases in activity levels in adults with asthma ( Khatri et al., 

### 24 2009 ; Feo Brito et al., 2007 ; Eiswerth et al., 2005 ; Ross et al., 2002 ) . In a recent panel 

### 25 study of adults with COPD, investigators found lag 1 of 8

- h max O 3 to be associated with 

### 26 increased odds of dyspnea and sputum changes but decreased odds of nasal discharge, 

### 27 wheeze, or upper respiratory symptoms ( Peacock et al., 2011 )

. 

### 28 In a panel study of children and adults with asthma, lag 1

- 3 avg of 8

- h max O 3 exposure 

### 29 was as sociated with increases in morning and evening symptom scores and frequency of 

### 30 asthma medication use ( Ross et al., 2002 ) . During one pollen season (May

- June 2000 or 

### 31 2001), Feo Brito et al. ( 2007 ) specifically followed a group of 137 adults who had asthma 

### 32 and pollen aller gy in central Spain. In the industrial Puertollano, a 40

- ppb increase in lag 

### 33Draft

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- 94 September 2011 3 of 1

- h max O 3 was associated with a 14.3% increase (95% CI: 3.6, 26.0) in the number 

### 1 of subjects reporting respiratory symptoms, adjusting only for time trend. There was a 

### 2 much weaker association in the less industrialized Ciudad Real with lower ambient air 

### 3 pollution concentrations and a narrower range of ambient O 3 concentrations (2.3% [95% 

### 4 CI:

- 14, 21%] per 40

- ppb increase in lag 4 of 1

- h max O 3 ). Park et al. ( 2005a ) followed 

### 5 adults with asthma in Korea during a peri od that included dust storms and found that a 

### 6 20

- ppb increase in lag 0 of 24

- h avg O 3 was associated with an increased odds of night 

### 7 symptoms (OR: 1.11 [95% CI: 0.96, 1.29]) but not cough (OR: 1.00 [95% CI: 0.94, 

### 8 1.06]) or rescue inhaler use (OR: 0.99 [95% CI: 0.94, 1.05]). 

### 9

Table 6 - 21 Mean and upper percentile ozone concentrations in epidemiologic studies examining respiratory symptoms and medication use in adults with respiratory disease Study Location Years/Season O 3 Averaging Time Mean/Median Concentrati on (ppb) Upper Percentile Concentrations (ppb) Khatri et al. ( 2009 ) Atlanta, GA 2003, 2005, 2006 Warm season 8
- h max 59 a Max: 73 a
Ross et al. ( 2002 ) East Moline, IL April
- October 1994 8
- h avg 41.5 Max: 78.3 Eiswerth et al. ( 2005 ) Glendora, CA 1983 Cold season 1
- h max NR NR
Peacock et al. ( 2011 ) London, England 1995
- 1997 All
- year 8
- h max 15.5 Autumn/Winter Max: 32 Spring/Summer Max: 74 Feo Brito et al. ( 2007 ) Ciudad Real and Puertollano, Spain 2000
- 2001 Warm season 1
- h max 65.9 (Ciudad Real) b 56.8 (Puertollano) b Max: 101.5 b (Ciudad Real); 70.5 b (Puertollano) Wiwatanadate et al. ( 2011 ) Chiang Mai, Thailand August 2005
- June 2006 24
- h avg 17.5 90th: 26.82 Max: 34.65 Park et al. ( 2005a ) Incheon, Korea March
- June 2002 24
- h avg Dust event days: 23.6 Control days: 25.1 NR NR = Not Reported, M ax = Maximum. a Individual
- level exposure 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). Studies also indicated that ambient O 3 exposure may result in decreases in activity levels 

### 10 in adults with asthma. Notably, although conducted over single seasons, these studies did 

### 11 not consider confounding by meteorological factors. In a cross

- sectional summer study in 

### 12 Atlanta, GA (described i n Section 6.2.1.2), Khatri et al. ( 2009 ) observed that a 30

- ppb 

### 13 increase in lag 2 of 8

- h max O 3 was associated with a 0.69

- point decrease (95% CI:

- 1.28, 

### 14

- 0.11) in the Juniper quality of life score, which incorporates indices for symptoms, 

### 15 mood, and activity limitations (7

- point scale). In a fall study conducted in the Los 

### 16 Angeles, CA area, Eiswert h et al. ( 2005 ) examined the activities of 64 individuals with 

### 17 asthma (age 16 years and older ). A 40

- ppb increase in 1

- h max O 3 was associated with a 

### 18 0.24% (95% CI: 0.08, 0.40%) lower probability of participation in indoor activities. The 

### 19 association with outdoor activities was positive but not statistically significant. Although 

### 20Draft

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- 95 September 2011 the authors ackno wledged that their findings were unexpected and may have been 

### 1 influenced by lack of control for potential confounders, they interpreted the decrease in 

### 2 indoor activities as rest replacing chores. In contrast, in a panel study of individuals with 

### 3 asthma (ag es 13

- 78 years) in Thailand, O 3 exposure was associated with a lower odds of 

### 4 symptoms that interfered with activities (OR: 0.74 [95% CI: 0.57, 0.96] per 20

- ppb 

### 5 increase in lag 4 of 24

- h avg O 3 ) ( Wiwatanadate and Liwsrisakun, 2011 )

. 

### 6

6.2.4.3 Populations not Restricted to Individuals with Asthma
Characteristics and ambient O 3 concentration data from studies of populations not 

### 7 restricted to individuals with asthma are presented in Table 6

- 22. In contrast with 

### 8 findings for lung function (Section 6.2.1.2), epidemiologic studies do not provide 

### 9 consistent evidence of associations between short

- term ambient O 3 exposure and 

### 10 increases in respiratory symptoms in children without asthma (Figure 6

- 13 and 

### 11 Table 6

- 23). 

### 12

Table 6 - 22 Mean and upper percentile ozone concentrations in epidemiologic studies examining respiratory symptoms in populations not restricted to individuals with asthma Study Location Years/Season O 3 Averaging Time Mean/Median Concentration (ppb) Upper Percentile Concentrations (ppb) Apte et al. ( 2008 ) Multiple U.S. cities (NR) 1994
- 1998 Winter or summer Workday avg (8:00 a.m. - 5:00 p.m.) 24
- h avg 34.2 a 25.5 a Max: 86.2 a Max: 67.3 a

Neas et al. ( 1995 ) Uniontown, PA June
- August 1990 12
- h avg (8:00 a.m. - 8:00 p.m.) 37.2 Max: 44.9 Triche et al. ( 2006 ) S outhwestern VA 199 5
- 1996 Warm season 1
- h max 8
- h max 24
- h avg 60.8 54.5 35.2 75th: 70.0, Max: 95.0 75th: 64.1, Max: 87.6 75th: 40.6, Max: 56.6 Linn et al. ( 1996 ) Rubidoux, Upland, Torrence, CA 1992
- 1993, 1993
- 1994 Fall and spring 24
- h avg 23 Max: 53 Gold et al. ( 1999 ) Mexico City, Mexico 1991 Winter, spring, fall 24
- h avg 52.0 Max: 103
Ward et al. ( 20 02 ) Birmingham and Sandwell, England 1997 Winter and summer 24
- h avg Winter median: 13.0 Summer median: 22.0 Winter Max: 33 Summer Max: 41 Hoek and Brunekreef ( 1995 ) Deurne and Enkhu izen, Netherlands 1989 March
- July 1
- h max Deurne: 57 Enkhuizen: 59 Max: 107 Max: 114 Moon et al. ( 2009 ) 4 cities, South Korea April
- May 2003 8
- h av g (10:00 a.m. - 6:00 p.m.) NR NR Rodriguez et al. ( 2007 ) Perth, Australia 1996
- 2003 All
- year 1
- h max 24
- h avg 33 28 Max: 95 Max: 74 NR = Not Reported, Max = Maximum. a Concentrations converted from μg/m 3 to ppb using the conversion factor of 0.51 assuming standard temperature (25°C) and pressure (1 atm).Draft

– Do Not Cite or Quote 6
- 96 September 2011 Among healthy children in Uniontown, PA, Neas et al. ( 1995 ) found a stronger 

### 1 association between O 3 exposure and evening cough using ambient concentrations 

### 2 weighted by time spent outdoors (OR: 2.20 [95% CI: 1.02, 4.75] per 30

- ppb increase in 

### 3 lag 0 of 12

- h avg [8:00 a.m.

- 8:00 p.m.]) than using unweighted concentrations (OR: 1.36 

### 4 [95% CI: 0.86, 2.13] per 30

- ppb increase in lag 0 of 12

- h avg [8:00 a.m.

- 8:00 p.m.]). 

### 5 Several other panel studies of school

- aged children, in which asthma prevalence ranged 

### 6 between 0 to 50%, reported null or negative associations between various averaging 

### 7 times and lags of ambient O 3 exposure and respiratory symptoms ( Moon et al., 2009 ; 

### 8 Rodriguez et al., 2007 ; Ward et al., 2002 ; Linn et al., 1996 ; Hoek and Brunekreef, 1995 )

. 

### 9 For example, a large study of 696 children in four regions in South Korea, Moon et al. 

### 10 ( 2009 ) observed that among all subjects, ORs of lag 0 8

- h avg O 3 w ith most respiratory 

### 11 symptoms were close to 1.0. In city

- specific analyses, O 3 exposure was only consistently 

### 12 associated with increases in URS (runny nose or sneezing), with the largest magnitude of 

### 13 association observed in Jeju island (OR: 1.08 [95% CI: 0. 96, 1.21] per a 30

- ppb increase 

### 14 in lag 0 8

- h avg O 3 ). Consistent with other studies conducted in Mexico City, Gold et al. 

### 15 ( 1999 ) reported a positive association between lag 1 of 24

- h avg O 3 exposure and phlegm 

### 16 in children; however, investigators acknowledged being unable to distinguish between 

### 17 the effects of the highly

- correlated O 3 and PM 10 (r = 0.75). 

### 18 In a recent study, O 3 exposure was associated with increased odds of respiratory 

### 19 symptoms in a group of infants who have mothers with asthma ( Triche et al., 2006 )

. 

### 20 Triche et al. ( 2006 ) followed 691 infants in southwestern VA \ for 83 days between June 

### 21 and August of 1995 and/or 1996 and found that a 20

- ppb increase in lag 0 of 24

- h avg O 3 

### 22 was associated with odds ratios (95% CI) of 2.34 (1.02, 5.37) for wheeze and of 3.63 

### 23 (1.81, 7.28) for difficulty breathing among the 61 infants who had mothers with asthma. 

### 24 Investigators estimated smaller magnitudes of association for 1

- h and 8

- h max O 3 

### 25 exposures. Smaller, statistically nonsignificant associat ions also were found in analyses 

### 26 that included all subjects (Figure 6

- 13 and Table 6

- 23). While these results suggested that 

### 27 children with mothers with asthma may be at greater risk of O 3 - related respiratory 

### 28 morbidity, the authors acknowledged that mothers with asthma may be more likely to 

### 29 report symptoms in their children and that transient wheeze, which is common in infants, 

### 30 may not predict respiratory morbidity later in life. In a study of children with parental 

### 31 history of asthma with follow

- up to an old er age (5 years), ambient O 3 exposure was not 

### 32 associated with increases in respiratory symptoms ( Rodriguez et al., 2007 )

. 

### 33Draft

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- 97 September 2011 LRS = lower respiratory symptoms, URS = Upper respiratory symptoms. Effect estimates 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 ozone exposures, respectively. 

### Figure 6 - 13 Associations of ambient ozone exposure with respiratory symptoms in studies not restricted to children with asthma.

Table 6 - 23 Addition al characteristics and quantitative data for studies presented in Figure 6 - 13 Study Location/ Population O 3 Lag O 3 Averaging Time Symptom Subgroup Odds Ratio (95% CI) a Ward et al. ( 2002 ) Birmingham and Sandwell, England Children 0
- 6 avg 24
- h avg Wheeze Shortness of breath 0.78 (0.22, 2.79) 1.80 (0.64, 5.06) Hoek and Brunekreef ( 1995 ) Enkhuizen, Netherlands Children 0 1
- h max Cough URS 0.95 (0.71, 1.25) 1.15 (1.00, 1.33) Moon et al. ( 2009 ) 4 cities, South Korea Children 0 24
- h avg URS All subjects Jeju Island 0.96 (0.90, 1.03) 1.08 (0.96, 1.21) Neas et al. ( 1995 ) Uniontown, PA Healthy children 0 12
- h avg (8:00 a.m. - 8:00 p.m.) Evening cough 2.20 (1.02, 4.75) b
Triche et al. ( 2006 ) southwestern VA Infants 0 8
- h max Wheeze All subjects Maternal asthma 1.60 (0.85, 3.00) 2.34 (1.02, 5.37) Gold et al. ( 1999 ) Mexico City, Mexico Children 1 24
- h avg Phlegm 1.04 (1.00, 1.07) 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 12
- h avg, and 24
- h avg O 3 , respectively. b O 3 exposures were weighted by the proportion of time spent outdoors. 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) O 3 Lag 0
- 6 avg

0

0

0 0

0 Symptom Wheeze Shortness of breath Cough URS URS
Evening cough Wheeze
Phlegm Subgroup

All subjects Jeju Island

All With asthmatic mothers ►

►

►

0 1 2 3 Odds ratio (95% CI)Draft

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- 98 September 2011 A recent cross

- sectional study examined 4,200 adult workers from 100 office buildings 

### 1 across the U.S. and found that a range of ambient O 3 exposure metrics, including the 24

- 

### 2 h, workday (8:00 a.m.

- 5:00 p.m.), and late workday (3:00 p.m.

- 6:00 p.m.) averages, were 

### 3 associated with increases in building

- related URS (nasal congestion or sore throat) and 

### 4 LRS (wheeze, shortness of breath, or chest t ightness) ( Apte et al., 2008 ) . Investigators 

### 5 suggested that the findings may have been attributable to formaldehyde and organic acids 

### 6 produced from O 3 - initiated reactions within buildings; however, additional data on indoor 

### 7 levels of volatile organic compounds, indoor O 3 , and infiltration rates is warranted to 

### 8 characterize whether the observed associations were attributable to the formation of these 

### 9 secondary species by ambient O 3 penetrating indoors 

### 10

6.2.4.4 Confounding in Epidemiologic Studies of Respiratory Symptoms and Medication Use Epidemiologic studies did not indicate that associaitons between short

- term O 3 exposure 

### 11 and respiratory symptoms were confounded by meteorological factors. Except where 

### 12 specified in the text, associations between ambient O 3 exposure and respiratory 

### 13 symptoms or medication use were found after adjusting for temperature in models. Some 

### 14 studies additionally included humidity in models ( Triche et al., 2006 ; Ross et al., 2002 ) or 

### 15 found no independent association with respiratory symptoms ( Thurston et al., 1997 )

. 

### 16 Several studies that exami ned populations with a high prevalence of atopy found O 3 - 

### 17 associated increases in respiratory symptoms and asthma medication use in copollutant 

### 18 models that included daily pollen counts ( Just et al., 2002 ; Ross et al., 2002 ; Gielen et al., 

### 19 1997 ) . Gielen et al. ( 1997 ) and Ross et al. ( 2002 ) specifically reported a high prevalence 

### 20 of grass pollen allergy in their study populations (52% and 38%, respectively). Ross et al. 

### 21 ( 2002 ) found similar associations of O 3 with morning symptoms and asthma medication 

### 22 use in a single

- pollutant model (e.g., 0. 21

- point [95% CI: 0.12, 0.30] increase in 

### 23 symptom score per 30

- ppb increase in lag 1

- 3 avg of 8

- h max O 3 ) and in a copollutant 

### 24 model with daily pollen counts (e.g., 0.20

- point [95% CI: 0.11, 0.29] increase in 

### 25 symptom score per 30

- ppb increase in lag 1

- 3 av g of 8

- h max O 3 ). Feo Brito et al. ( 2007 ) 

### 26 specifically followed a group of adults in central Spain, all of whom had both asthma and 

### 27 pollen allergy. In one city, O 3 was associated with an increase in the number of subjects 

### 28 report ing symptoms. A smaller, statistically nonsignificant effect estimate was obtained 

### 29 for pollen. Conversely, in another city, pollen was associated with an increased incidence 

### 30 of respiratory symptoms, whereas O 3 was not. While copollutant modeling was not 

### 31 co nducted, in both locations, O 3 and pollen concentrations were weakly correlated, 

### 32 indicating that the findings for O 3 were not likely confounded by pollen. Rather, the 

### 33Draft

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- 99 September 2011 results suggested that O 3 and pollen may have independent effects that vary between 

### 1 locat ions, depending on the mix of airborne pollutants. 

### 2

Table 6 - 24 Associations between short - term ozone exposure and respiratory symptoms in single - and copollutant models Study Location/ Population O 3 Exposure Data Symptom O 3 - associated OR in Single - Pollutant

Model (95% CI) a O 3 - associated OR in Copollutant Model (95% CI) a Mortimer et al. ( 2002 ) Bronx, East Harlem, NY; Baltimore, MD; Washington, DC; Detroit, MI, Cleveland, OH; Chicago, IL; St. Louis, MO (NCICAS) Children with asthma 8
- h avg (10:00 a.m.
- 6:00 p.m.) Lag 1
- 4 avg Morning symptoms 8 cities with SO 2 data 1.35 (1.04, 1.69) 7 ciites with NO 2 data 1.25 (0.94, 1.67) 3 cities with PM 10 data 1.21 (0.61, 2.41) with lag 1
- 2 avg, 3
- h avg SO 2 1.23 (0.94, 1.61) with lag 1
- 6 avg, 24
- h avg NO 2 1.14 (0.85, 1.55) with lag 1
- 2 avg, 24
- h avg PM 10 1.08 (0.49, 2.39) Thurston et al. ( 1997 ) CT River Valley Children with asthma attending summer camp 1
- h max Lag 0 Chest symptoms 1.21 (1.12, 1.31) b with lag 0, 12
- h avg sulfate 1.19 (1.06, 1.35) b Romieu et al. ( 1996 ) Mexico City, Mexico Children with asthma 1
- h max Lag 0 LRS 1.07 (1.02, 1.12) with lag 0, 24
- h avg PM 2.5 1.06 (1.02, 1.10) Romieu et al. ( 1997 ) Mexico City, Mexico Children with asthma 1
- h max Lag 0 LRS 1.09 (1.04, 1.14) with lag 0, 24
- h avg PM 10 1.09 (1.01, 1.19) LRS = Lower res piratory symptoms.
a Effect estimates 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. Robust associations between O 3 exposure and respiratory symptoms also were observed 

### 3 in copollutant models that included PM 2.5 , PM 10 , sulfate, SO 2 , or NO 2 (Table 6

- 24). 

### 4 Information on confounding in asthma medication use associations was more limited. 

### 5 The association between O 3 and bronchodilator use did not change in Gent et al. ( 2003 ) 

### 6 after adjusting for PM 2.5 but decreased in magnitude in Thurston et al. ( 1997 ) af ter 

### 7 adjusting for 12

- h avg sulfate. For respiratory symptoms and medication use, copollutant 

### 8 associations remained robust after adjusting for O 3 . Notably, studies examined different 

### 9 averaging times for O 3 (1

- h max or 8

- h avg) and co

- pollutants (3

- h to 24

- h avg) and 

### 10 reported a range of correlations with co

- pollutants. Two studies conducted concurrently 

### 11 in two regions of Mexico City examined lag 0 exposures of 1

- h max O 3 and 24

- h avg 

### 12 PM 10 or PM 2.5 and found robust associations with respiratory symptoms for bo th O 3 and 

### 13 co - pollutants ( Romieu et al., 1997 ; Romieu et al., 1996 ) . Romieu et al. ( 1997 ) reported a 

### 14 moderate correlation between 1

- h max O 3 and 24

- h avg PM 10 (r = 0.47). Thurston et al. 

### 15 ( 1997 ) and Gent et al. ( 2003 ) found 1

- h max O 3 concentrations to be highly correlated 

### 16 with 12

- h avg sulfate (r=0.74) and 24

- h avg PM 2.5 (r=0.77), respectively, thus the 

### 17 copollutant results should be inter preted with caution. The association between O 3 

### 18 exposure and respiratory symptoms observed in NCICAS was robust in two

- pollutant 

### 19Draft

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- 100 September 2011 models with SO 2 , NO 2 , and or PM 10 ; however, the interpretation is complicated because 

### 1 of the different averaging times and lags of exposure examined for O 3 and co

- pollutants 

### 2 ( Mortimer et al., 2002 ) (Table 6

- 24). Also diffic ult are interpretations of the robust 

### 3 associations observed between ambient O 3 exposure and respiratory symptoms after 

### 4 adjusting for multiple pollutants (i.e., PM 2.5 plus NO 2 or PM 10

- 2.5 ) ( Escamilla

- Nuñez et al., 

### 5 2008 ; Triche et al., 2006 )

. 

### 6

6.2.4.5 Summary of Epidemiologic Studies of Respiratory Symptoms and Asthma Medication Use With a majority of investigation focused on individuals with asthma, the collective 

### 7 epidemiologic evidence clearly demonstrates that short

- term ambient O 3 exposure is 

### 8 associated with increases in respiratory s ymptoms and asthma medication use in children 

### 9 with asthma. In a smaller body of literature, several studies find associations in adults 

### 10 with asthma. In comparison, evidence has not consistently indicated that short

- term O 3 

### 11 exposure is associated with reduc ed activity levels in children or adults with asthma. 

### 12 Although O 3 exposure has been associated with school absenteeism among children with 

### 13 asthma, only Gilliland et al. ( 2001 ) examined absences specifically for respiratory causes 

### 14 and found associations with O 3 exposure lag periods shorter than 14 days. Epidemiologic 

### 15 studies do not provide consistent evidence of association between short

- term ambient O 3 

### 16 exposure and respiratory symptoms in children without asthma. 

### 17 Collectively, epidemiologic studies most frequently examined 1

- h max and 8

- h max or 

### 18 avg O 3 exposures, and the few studies that examined both averaging times found s imilar 

### 19 magnitudes of associations with respriatory symptoms ( Triche et al., 2006 ; Delfino et al., 

### 20 2003 ; Gent et al., 2003 ) . Several studies found increases in respiratory symptoms with O 3 

### 21 exposures averaged over 12 to 24 hours ( Triche et al., 2006 ; Jalaludin et al., 2004 ; Gold 

### 22 et al., 1999 ; Neas et al., 1999 ) . E pidemiologic studies examined associations of 

### 23 respiratory symptoms with single

- day O 3 concentrations lagged from 0 to 5 days as well 

### 24 concentrations averaged over 2 to 19 days. While O 3 exposures lagged 0 or 1 days were 

### 25 consistently associated with respirat ory symptoms, several studies that examined a range 

### 26 of exposure lags found larger effect estimates for multiday averages (3

- to 6

- days) of O 3 

### 27 exposure ( Escamilla

- Nuñez et al., 2008 ; Romieu et al., 2006 ; Rabinovitch et al., 2004 ; 

### 28 Just et al., 2002 ; Mortimer et al., 2002 ; Ross et al., 2002 ) . These epidemiologic findings 

### 29 are in contrast with those from controlled human exposure studies that find attenuated 

### 30 symptom responses with O 3 exposures repeated over several days (Section 6.2.1.1). The 

### 31 epidemiologic findings for lagged O 3 exposures or those accumulated over several days 

### 32 are well

- supported by the action of O 3 to sen sitize bronchial smooth muscle to 

### 33 hyperreactivity, thus acting as a primer for subsequent exposure to antigens such as 

### 34Draft

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- 101 September 2011 allergens (Section 5.3.5). In several of the studies of individuals with asthma, the 

### 1 prevalence of atopy was high (50

- 100%), and sensitiz ation of airways provides a 

### 2 biologically plausible mode of action by which lagged or multiday average O 3 exposures 

### 3 are associated with increases in respiratory symptoms in these studies of individuals with 

### 4 asthma. 

### 5 Epidemiologic evidence did not indicate th at associations between short

- term O 3 

### 6 exposure and respiratory symptoms were confounded by temperature or pollen. In the 

### 7 limited analysis of confounding by co

- pollutants (primarily PM), robust associations with 

### 8 respiratory symptoms were observed for O 3 ; ho wever, disentangling the independent 

### 9 effects of O 3 exposure in many studies is complicated due to the high correlations 

### 10 observed between O 3 and PM, different averaging times and lags of exposure examined 

### 11 for co

- pollutants, and the multiple co

- pollutants in cluded in models. Nonetheless, the 

### 12 consistency of association among individuals with asthma with and without adjustment 

### 13 for copollutant exposures combined with evidence from controlled human exposure 

### 14 studies for the direct effect of O 3 exposure provide substantial evidence for the 

### 15 independent effects of ambient O 3 exposure on increases in respiratory symptoms 

### 16

6.2.5 Lung Host Defenses The mammalian respiratory tract has a number of closely integrated defense mechanisms 

### 17 that, when functioning n ormally, provide protection from the adverse effects of a wide 

### 18 variety of inhaled particles and microbes. For simplicity, these interrelated defenses can 

### 19 be divided into two major parts: (1) nonspecific (transport, phagocytosis, and bactericidal 

### 20 activity) and (2) specific (immunologic) defense mechanisms. A variety of sensitive and 

### 21 reliable methods have been used to assess the effects of O 3 on these components of the 

### 22 lung ’ s defense system to provide a better understanding of the health effects associated 

### 23 wi th the inhalation of this pollutant. The previous O 3 AQCD states that animal 

### 24 toxicological studies provide extensive evidence that acute O 3 exposures as low as 0.08 to 

### 25 0.5 ppm can cause increases in susceptibility to infectious diseases due to modulation o f 

### 26 lung host defenses. Tables 6

- 6 through 6

- 9, beginning on p. 6

- 41 of the 1996 O 3 AQCD 

### 27 ( U.S. EPA, 1996a ) , and Table AX5

- 7, beginning on p. AX5

- 8 of the 2006 O 3 AQCD 

### 28 ( U.S. EPA, 2006b ) , present studies on the effects of O 3 on host defense mechanisms. This 

### 29 section discusses the various components of host defenses, such as the mucociliary 

### 30 escalator, the phagocytic, bactericidal, and regulatory role of the alveol ar macrophages 

### 31 (AMs), the adaptive immune system, and integrated mechanisms that are studied by 

### 32 investigating the host ’ s response to experimental pulmonary infections. 

### 33Draft

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- 102 September 2011 

### 6.2.5.1 Mucociliary Clearance The mucociliary system is one of the lung ’ s primary defense mecha nisms. It protects the 

### 1 conducting airways by trapping and quickly removing material that has been deposited or 

### 2 is being cleared from the alveolar region by migrating alveolar macrophages. Ciliary 

### 3 movement directs particles trapped on the overlying mucous l ayer toward the pharynx, 

### 4 where the mucus is swallowed or expectorated. 

### 5 The effectiveness of mucociliary clearance can be determined by measuring such 

### 6 biological activities as the rate of transport of deposited particles; the frequency of ciliary 

### 7 beating; structural integrity of the ciliated cells; and the size, number, and distribution of 

### 8 mucus - secreting cells. Once this defense mechanism has been altered, a buildup of both 

### 9 viable and nonviable inhaled substances can occur on the epithelium and may jeopard ize 

### 10 the health of the host, depending on the nature of the uncleared substance. Impaired 

### 11 mucociliary clearance can result in an unwanted accumulation of cellular secretions, 

### 12 increased infections, chronic bronchitis, and complications associated with chroni c 

### 13 obstructive pulmonary disease. A number of previous studies with various animal species 

### 14 have examined the effect of O 3 exposure on mucociliary clearance and reported 

### 15 morphological damage to the cells of the tracheobronchial tree from acute and sub



### 16 chroni c exposure to O 3 0.2 ppm and higher. The cilia were either completely absent or 

### 17 had become noticeably shorter or blunt. After placing these animals in a clean

- air 

### 18 environment, the structurally damaged cilia regenerated and appeared normal ( U.S. EPA, 

### 19 1986 ) . Based on such morphological observations, related effects such as ciliostasis, 

### 20 increased mucus secretions, and a slowing of mucociliary transport rates might be 

### 21 expected. How ever, no measurable changes in ciliary beating activity have been reported 

### 22 due to O 3 exposure alone. Essentially no data are available on the effects of prolonged 

### 23 exposure to O 3 on ciliary functional activity or on mucociliary transport rates measured in 

### 24 t he intact animal. In general, functional studies of mucociliary transport have observed a 

### 25 delay in particle clearance soon after acute exposure. Decreased clearance is more 

### 26 evident at higher doses (1 ppm), and there is some evidence of tolerance/adaptation for 

### 27 these effects ( U.S. EPA, 1986 ) . However, no recent studies have evaluated the effects of 

### 28 O 3 on mucociliary clearance. 

### 29

6.2.5.2 Alveolobronchiolar Transport Mechanism
In addition to the transport of particles deposited on the mucous surface layer of the 

### 30 conducting airways, particles deposited in the deep lung may be removed either up the 

### 31 respiratory tract or through interstitial pathways to the lymphatic system. The pivotal 

### 32 mechani sm of alveolobronchiolar transport involves the movement of AMs with 

### 33Draft

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- 103 September 2011 phagocytized particles to the bottom of the mucociliary escalator. Failure of the AMs to 

### 1 phagocytize and sequester the deposited particles from the vulnerable respiratory 

### 2 membrane can lea d to particle entry into the interstitial spaces. Once lodged in the 

### 3 interstitium, particle removal is more difficult and, depending on the toxic or infectious 

### 4 nature of the particle, its interstitial location may allow the particle to set up a focus for 

### 5 p athologic processes. Although some studies show reduced early (tracheobronchial) 

### 6 clearance after O 3 exposure, late (alveolar) clearance of deposited material is accelerated, 

### 7 presumably due to macrophage influx (which in itself can be damaging due to protea ses 

### 8 and oxidative reactions in these cells). In an important older study investigating the 

### 9 effects of longer term O 3 exposure on alveolobronchiolar clearance, rats were exposed to 

### 10 an urban pattern of O 3 (continuous 0.06 ppm, 7 days/week with a slow rise to a peak of 

### 11 0.25 ppm and subsequent decrease to 0.06 ppm over a 9 h period for 5 days/week) for 

### 12 6 weeks and were exposed 3 days later to chrysotile asbestos, which can cause pulmonary 

### 13 fibrosis and neopla sia ( Pinkerton et al., 1989 ) . After 30 days, the lungs of the O 3 - exposed 

### 14 animals had twice the number and mass of asbestos fibers as the air

- exposed rats. New 

### 15 evaluations of O 3 effects on alveolar clearance have not been performed. 

### 16

6.2.5.3 Alveolar Macrophages Within the gaseous exchange region of the lung, the first line of defense a gainst 

### 17 microorganisms and nonviable particles that reach the alveolar surface is the AM. This 

### 18 resident phagocyte is responsible for a variety of activities, including the detoxification 

### 19 and removal of inhaled particles, maintenance of pulmonary sterility v ia destruction of 

### 20 microorganisms, and interaction with lymphocytes for immunologic protection. Under 

### 21 normal conditions, AMs seek out particles deposited on the alveolar surface and ingest 

### 22 them, thereby sequestering the particles from the vulnerable respira tory membrane. To 

### 23 adequately fulfill their defense function, the AMs must maintain active mobility, a high 

### 24 degree of phagocytic activity, and an optimally functioning biochemical and enzyme 

### 25 system for bactericidal activity and degradation of ingested mater ial. As discussed in 

### 26 previous AQCDs, short periods of O 3 exposure can cause a reduction in the number of 

### 27 free AMs available for pulmonary defense, and these AMs are more fragile, less 

### 28 phagocytic, and have decreased lysosomal enzyme activities required for killing 

### 29 pathogens. For example, in results from earlier work in rabbits, a 2

- h exposure to 0.1 ppm 

### 30 O 3 inhibited phagocytosis and a 3

- h exposure to 0.25 ppm decreased lysosomal enzyme 

### 31 activities ( Driscoll et al., 1987 ; Hurst et al., 1970 ) . Similarly, AMs from rats exposed to 

### 32 0.1 ppm O 3 for 1 or 3 weeks exhibited reduced hydrogen peroxide production ( Cohen et 

### 33 al., 2002 ) . A controlled human exposure stu dy reported decrements in the ability of 

### 34 alveolar macrophages to phagocytize yeast following exposure of healthy volunteers to 

### 35Draft

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- 104 September 2011 80 to 100 ppb O 3 for 6.6

- h during moderate exercise ( Devlin et al., 1991 ) . Although the 

### 1 percentage of phagocytosis

- capable macropha ges was unchanged by O 3 exposure, the 

### 2 number of yeast engulfed was reduced when phagocytosis was complement

- dependent. 

### 3 However, there was no difference in the ability of macrophages to produce superoxide 

### 4 anion after O 3 exposure. These results are consistent with those from another controlled 

### 5 human exposure study in which no changes in the level of lysosomal enzymes or 

### 6 superoxide anion production were observed in macrophages lavaged from healthy human 

### 7 subjects exposed to 400 ppb O 3 for 2 h with heavy intermittent exercise ( Koren et al., 

### 8 1989 )

. More recently, Lay et al. ( 2007 ) observed no difference in phagocytic activity or 

### 9 oxidative burst capacity in macrophages or monocytes from sputum or blood collected 

### 10 from healthy volunteers af ter a 2

- hour exposure to 400 ppb O 3 with moderate intermittent 

### 11 exercise. However, another study found that oxidative burst and phagocytic activity in 

### 12 macrophages increased in GSTM1 null subjects compared to GSTM1 positive subjects, 

### 13 who had relatively uncha nged macrophage function parameters after an O 3 exposure 

### 14 identical to that of Lay et al. described above ( Alexis et al., 2009 ) . Collectively, these 

### 15 studies demonstrate that O 3 can affect multiple steps or aspects required for proper 

### 16 macrophage function, but any concentration

- resp onse relationship appears complex and 

### 17 genotype may be a consideration. A few other recent studies have evaluated ozone ’ s 

### 18 effects on macrophage function, but these are of questionable relevance due to the use of 

### 19 in vitro exposure systems and amphibian anima l models ( Mikerov et al., 2008b ; Dohm et 

### 20 al., 2005 ; Klestadt et al., 2005 )

. 

### 21

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 and dependent on the exposure 

### 22 regimen and the observation period. According to toxicological studies it appears that the 

### 23 T

- cell

- dependent functions of the immune system are more affected than B

- cell



### 24 dependent functions ( U.S. EPA, 2006b ) . Generally, there is an early immunosuppressive 

### 25 effect that subsides with continued O 3 exposure, resulting in either a return to normal 

### 26 responses or an enhancement of immune responses. However, this is not alw ays the case 

### 27 as Aranyi ( 1983 ) showed decreased T

- cell mitogen reacti ons in mice after subchronic 

### 28 (90

- day) exposure to 0.1 ppm O 3 . Earlier studies report changes in cell populations in 

### 29 lymphatic tissues ( U.S. EPA, 2006b ) . A more recent study in mice demonstrated that 

### 30 numbers of certain T cell subsets in t he spleen were reduced after exposure to 0.6 ppm O 3 

### 31 (10h/day x 15d) ( Feng et al., 2006 )

. 

### 32Draft

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- 105 September 2011 The inflammatory effec ts of O 3 involve the innate immune system, and as such can affect 

### 1 adaptive (or acquired) immunity via alterations in antigen presentation and costimulation 

### 2 by innate immune cells such as macrophages and dendritic cells. Several recent 

### 3 controlled human expo sure studies demonstrate increased expression of molecules 

### 4 involved in antigen presentation or costimulation. Lay et al. ( 2007 ) collected sputum 

### 5 monocytes from healthy volunteers exposed to 400 ppb O 3 for 2 h with moderate 

### 6 intermittent exercise and detected increases in HLA

- DR, used to present antigen to T 

### 7 cells, and CD86, a costimulator y marker necessary for T cell activation. Upregulation of 

### 8 HLA

- DR was also observed by Alexis et al. ( 2009 ) in sputum dendritic cells and 

### 9 macrophages from GSTM1 null subjects exposed to 400 ppb O 3 for 2 h with moderate 

### 10 intermittent exercise. On airway monocytes from healthy volunteers 24 hours after 

### 11 exposure to 80 ppb O3 for 6.6 h with moderate intermittent exercise, HLA

- DR, CD86, 

### 12 and CD14 (a molecule involved in bacterial endotoxin reacitivity) we re increased, 

### 13 whereas CD80, a costimulatory molecule of more heterogeneous function, was decreased 

### 14 ( Alexis et al., 2010 )

. Patterns of expression on macr ophages were similar, except that 

### 15 HLA

- DR was found to be significantly decreased after O 3 exposure and CD86 was not 

### 16 significantly altered. An increase in IL

- 12p70, a macrophage and dendritic cell product 

### 17 that activates T cells, was correlated with increase d numbers of dendritic cells. It should 

### 18 be noted that these results are reported as comparisons to baseline as there was no clean 

### 19 air control ( Alexis et al., 2010 ; Alexis et al., 2009 ) . Another controlled human exposure 

### 20 study reported no increase in IL

- 12p70 in sputum from healthy, atopic, or atopic 

### 21 asthmatic subjects following a 2

- hour exposure to 400 ppb O 3 with intermittent moderate 

### 22 exercise ( Hernandez et al., 2010 ) . Levels of HLA

- DR, CD14 and CD86 were not 

### 23 increased on macrophages collected from any of these subjects. It is difficult to compare 

### 24 these results to those of Lay et al. ( 2007 ) and Alexis et al. ( 2010 ) due to differences in O 3 

### 25 concentration, cell type examined, and timing of postexposure analysis. 

### 26 Although no controlled human exposure studies have examined the effects of O 3 on the 

### 27 ability to mount antigen

- specific responses, upregulation of markers associated with 

### 28 innate immune activation and antigen presentation could potentially enhance adaptive 

### 29 immunity and increase immunologic responses to antigen. While this may bolster 

### 30 defenses against infection, it also may enhance allergic responses (Section 6.2.6). 

### 31 In animal models, O 3 has been found to alter responses to antigenic stimulation. For 

### 32 example, antibody responses to a T

- cell

- dependent antigen were suppressed after a 

### 33 56

- d ay exposure of mice to 0.8 ppm O 3 , and a 14

- day exposure to 0.5 ppm O 3 decreased 

### 34 the antiviral antibody response following influenza virus infection ( Jakab and Hmieleski, 

### 35 1988 ) ; the latter impairment may pave the way for lowered resistance to reinfection. The 

### 36 immune response is highly influenced by the tempo ral relationship between O 3 exposure 

### 37 and antigenic stimulation. When O 3 exposure preceded Listeria infection, there were no 

### 38Draft

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- 106 September 2011 effects on delayed

- type hypersensitivity or splenic lymphoproliferative responses; 

### 1 however, when O 3 exposure occurred during or afte r Listeria infection was initiated, 

### 2 these immune responses were suppressed ( Van Loveren et al., 1988 ) . In another study, a 

### 3 reduction in mitogen activated T

- cell proliferation was observed after exposure to 

### 4 0.6 ppm for 15 d ays , and could be ameliorated by antioxidant supplementation. Ant igen



### 5 specific proliferation decreased by 60%, indicating attenuation of the acquired immunity 

### 6 needed for subsequent memory responses ( Feng et al., 2006 ) . O 3 exposure also skewed 

### 7 the ex

- vivo cytokine responses elicited by non

- specific stimulation toward inflammation, 

### 8 decreasing IL

- 2 and increasing IFN

- γ. Modest decreases in immune function assessed in 

### 9 the offspring of O 3 - exposed dams (mice) were observed by Sharkhuu et al. ( 2011 ) . The 

### 10 ability to mount delayed

- type hypersensitivity responses was significantly suppressed in 

### 11 42 day

- old offspring when dams were exposed to 0.8 or 1.2 ppm O 3 , but not 0.4 ppm, 

### 12 from gestational day 9

- 18. Humoral responses to immunization with sheep red blood 

### 13 cells were unaffected, as were other immune parameters such as splenic populations of 

### 14 CD45+ T cells, iNKT cells, and levels of IFN

- γ, IL

- 4, and IL

- 17 in the BALF. Generally, 

### 15 continuous exposure t o O 3 impairs immune responses for the first several days of 

### 16 exposure, followed by an adaptation to O 3 that allows a return of normal immune 

### 17 responses. Most species show little effect of O 3 exposures prior to immunization, but 

### 18 show a suppression of response s to antigen in O 3 exposures post

- immunization. 

### 19

Microbial Infection Bacterial infection A relatively large body of evidence shows that O 3 increases susceptibility to bacterial 

### 20 infections. The majority of studies in this area were conducted before the 1996 O 3 AQCD 

### 21 was published and many are included in Table 6

- 9 on p. 6

- 53 of that document. Known 

### 22 contributing factors are impaired mucociliary streaming, altered chemotaxis/motility, 

### 23 defective phagocytosis of bacteria, decreased production of lysosomal enzymes or 

### 24 superoxide radicals by alveolar macrophages, and decreased IFN

- γ levels. In animal 

### 25 models of bacterial infection, exposure to 0.08 ppm O 3 increases streptococcus

- induced 

### 26 mortality, regardless of whether O 3 exposure precedes or follows infection ( Miller et al., 

### 27 1978 ; Coffin and Gardner, 1972 ; Coffin et al., 1967 ) . Increases in mortality are due to the 

### 28 infectious agent, thereby reflecting functional impairment of host defenses. Exercise and 

### 29 copollutants can enhance oz one ’ s effects in infectivity models. Although both mice and 

### 30 rats exhibit impaired bactericidal macrophage activity after O 3 exposure, mortality due to 

### 31 infection is only observed in mice. Additionally, although mice and humans share many 

### 32 host defense mechan isms, there is little compelling evidence from epidemiologic studies 

### 33 (Section 6.2.7.3). 

### 34Draft

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- 107 September 2011 Viral infection Only a few studies, described in previous AQCDs, have examined the effects of O 3 

### 1 exposure on the outcome of viral respiratory infection (see Table 6

- 9 on p. 6

- 53 of the 

### 2 1996 O 3 AQCD. Some studies show increased mortality, while others show diminished 

### 3 severity and increased survival time. There is little to no evidence from studies of animals 

### 4 or humans to suggest that O 3 increases the incidence of respiratory viral infection in 

### 5 humans. In human volunteers infected with rhinovirus prior to O 3 exposure (0.3 ppm for 

### 6 5 consecutive days), no effect on viral titers, IFN

- γ production, or blood lymphocyte 

### 7 proliferative responses to viral antigen was observed ( Henderson et al., 1988 ) . In vitro 

### 8 cell culture studies of human bronchial epithelial cells indicate O 3 - induced exacerbation 

### 9 of human rhinovirus infection ( Spannhake et al., 2002 ) , but this is of limited relevance. 

### 10 Newer studies on the interactions of O 3 and viral infections have not been published. 

### 11 Natura l killer (NK) cells, which destroy virally infected cells and tumors in the lung, 

### 12 appear to be inhibited by higher concentrations of O 3 and either unaffected or stimulated 

### 13 at lower concentrations. Several studies show decreases in NK cell activity followin g 

### 14 acute exposures ranging from 0.8 to 1 ppm ( Gilmour and Jakab, 1991 ; Van Loveren et 

### 15 al., 1990 ; Burleson et al., 1989 ) . However, Van Loveren et al. ( 1990 ) showed that a 

### 16 1

- week exposure to 0.2 or 0.4 ppm O 3 increased NK cell activit y, and an urban pattern of 

### 17 exposure (base of 0.06 ppm with peaks of 0.25 ppm) had no effect on NK cell activity 

### 18 after 1, 3, 13, 52, or 78 weeks of exposure ( Selgrade et al., 1990 ) . A more recent study 

### 19 demonstrated a 35% reduction in NK cell activity after exposure of mice to 0.6 ppm O 3 

### 20 (10h/day x 15d) ( Feng et al., 2006 ) . The defective IL

- 2 producti on demonstrated in this 

### 21 study may impair NK cell activation. Alternatively, NK cell surface charge may be 

### 22 altered by ROS, decreasing their adherence to target cells ( Nakamura and Matsunaga, 

### 23 1998 )

. 

### 24 Summary: Infections Taken as a whole, the data clearly indicate that an acute O 3 exposure impairs the host 

### 25 defense capability of both humans and animals, primarily by depressing alveolar 

### 26 macrophage function a nd perhaps also by decreasing mucociliary clearance of inhaled 

### 27 particles and microorganisms. This suggests that humans exposed to O 3 could be 

### 28 predisposed to bacterial infections in the lower respiratory tract. The seriousness of such 

### 29 infections may depend on how quickly bacteria develop virulence factors and how 

### 30 rapidly PMNs are mobilized to compensate for the deficit in alveolar macrophage 

### 31 function. To date, a limited number of epidemiologic studies have examined associations 

### 32 between O 3 exposure and HA/ED for respiratory infection, pneumonia, or influenza. 

### 33 Results have been mixed, and in some cases conflicting (see Sections 6.2.7.2 and 

### 34 6.2.7.3). With the exception of influenza, it is difficult to ascertain whether cases of 

### 35 respiratory infection or pneumonia are of viral or bacterial etiology. A study that 

### 36Draft

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- 108 September 2011 examined the association between O 3 exposure and respiratory hospital admissions in 

### 1 response to an increase in influenza intensity did observe an increase in respiratory 

### 2 hospital admissions ( Wong et al., 2009 ) , but information from toxicological studies of O 3 

### 3 and viral infections is ambiguous. 

### 4

6.2.6 Allergic and Asthma - Related Responses Effects resulting from combined ex posures to O 3 and allergens have been studied in a 

### 5 variety of animal species, generally as models of experimental asthma. Pulmonary 

### 6 function and airways hyperresponsiveness in animal models of asthma are discussed in 

### 7 Sections 6.2.1.7 and 6.2.2.2. Previous evidence indicates that O 3 exposure skews immune 

### 8 responses toward an allergic phenotype. For example, Gershwin et al. ( 1981 ) reported 

### 9 that O 3 (0.8 and 0.5 ppm for 4 days) exposure caused a 34

- fold increase in the number of 

### 10 IgE (allergic antibody)

- containing cells in the lungs of mice. In general, the number of 

### 11 IgE

- containing cells correlated positively with levels of anaphylactic sensitivity. In 

### 12 humans, allergic rhinoconjunctivitis symptoms are associated with increases in ambient 

### 13 O 3 concentrations ( Riediker e t al., 2001 ) . Recent controlled human exposure studies have 

### 14 observed O 3 - induced changes indicating allergic skewing. Airway eosinophils, which 

### 15 participate in allergic disease and inflammation, were observed to increase in atopic, 

### 16 mildly asthmatic volunteers 18 h following a 7.6

- hour exposure to 160 ppb O 3 with light 

### 17 intermittent exercise ( Peden et al., 1997 ) . No increase in airway eosinophils was ob served 

### 18 4 h after exposure of healthy, atopic, or atopic asthmatic subjects to 400 ppb O 3 for 2 h 

### 19 with moderate intermittent exercise ( Hernandez et al., 2010 ) . However, atopic subjects 

### 20 did exhibit increased IL

- 5, a cytokine involved in eosinophil recruitment and activ ation, 

### 21 suggesting that perhaps these two studies observed the same effect at different time 

### 22 points. Several epidemiologic studies discussed in Section 7.2.5 describe an association 

### 23 between eosinophils and long

- term O 3 exposure, consistent with chronic expo sure studies 

### 24 in non

- human primates. Hernandez et al. ( 2010 ) also observed increased expression of 

### 25 high and low affinity IgE receptors on sputum macrophages from atopic asthmatics, 

### 26 which may enhance IgE

- dependent inflammation. Sputum levels of IL

- 4 and IL

- 13, both 

### 27 pro - a llergic cytokines that aid in the production of IgE,were unaltered in any group. The 

### 28 lack of increase in IL

- 4 levels in sputum reported by Hernandez et al., along with 

### 29 increased IL

- 5, is consistent with results from Bosson et al. ( 2003 ) , in which IL

- 5 (but not 

### 30 IL

- 4 levels) increased in bronchial epithelial biopsy specimens following exposure of 

### 31 mild atopic asthmatics to 200 ppb O 3 for 2 h with moderate intermittent exercise. IL

- 5 

### 32 was not elevated in specimens obtained from healthy (non

- asthmatic) O 3 - exposed 

### 33 subjects. Collectively, fi ndings from these studies suggest that O 3 can induce or enhance 

### 34 certain components of allergic inflammation in atopic and atopic asthmatic individuals. 

### 35Draft

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- 109 September 2011 Ozone enhances inflammatory and allergic responses to allergen challenge in sensitized 

### 1 animals. Short

- te rm exposure (2 days) to 1 ppm O 3 exacerbated allergic rhinitis and lower 

### 2 airway allergic inflammation in Brown Norway rats, a rat strain that is comparatively less 

### 3 sensitive to O 3 than other rats or humans ( Wagner et al., 2009 ; Wagner et al., 2007 )

. 

### 4 OVA

- sensitized rats were intranasally challenged with OVA on days 1 and 2, and 

### 5 exposed to 0 or 1 ppm O 3 (8 h/day) on days 4 and 5. Analysis at day 6 indicated that O 3 

### 6 exposure enhanced intraepithelial mucosubstances in the nose and airways, induced cys



### 7 LTs, MCP

- 1, and IL

- 6 production in BALF, and upregulated expression of the 

### 8 proallergic cytokines IL

- 5 and IL

- 13. These changes were not evident in non

- allergic 

### 9 controls. All of these responses were blunted by gamma

- tocopherol (γT; vitamin E) 

### 10 therapy. γT ne utralizes oxidized lipid radicals, and protects lipids and proteins from 

### 11 nitrosative damage from NO

- derived metabolites. Farraj et al. ( 2010 ) exposed allergen



### 12 sensitized adult male BALB/c mice to 0.5 ppm O 3 for 5 hours once per week for 4 weeks. 

### 13 Ozone exposure and O 3 /DEP (2.0 mg/m 3 ) co

- exposure of OVA

- sensitized mice elicited 

### 14 significantly greater serum IgE levels than in DEP

- exposed OVA

- sensitized mice (98% 

### 15 and 89% increases, respectively). Ozone slightly enhanced levels of BAL IL

- 5, but 

### 16 despite increases in IgE, caused a significant decrease in BA L IL

- 4 levels. IL

- 10, IL

- 13, 

### 17 and IFN

- γ levels were unaffected. Lung resistance and elastance were unaffected in 

### 18 allergen sensitized mice exposed solely to 0.5 ppm O 3 once a week for 4 weeks ( Farraj et 

### 19 al., 2010 ) . However, co

- exposure to O 3 and diesel exhaust particles increased lung 

### 20 resistance. 

### 21 In addition to exacerbating existing allergic responses, O 3 can also act as an adjuvant to 

### 22 produce sensitization in the respiratory tract. In a model of murine asthma, using OVA 

### 23 free of detectable endotoxin, inclusion of 1 ppm O 3 during the initial exposures to OVA 

### 24 (2 h, days 1 and 6) enhanced the inflammatory and allergic responses to subsequent 

### 25 allergen challenge ( Hollingsworth et al., 2010 ) . Compared to air exposed animals, O 3 

### 26 exposed mice exhibited significantly higher levels of total cells, macrophages, 

### 27 eosinophils, and PMNs in BALF, and increased total serum IgE. Pro

- allergic cytokines 

### 28 IL

- 4, and IL

- 5 were also significantly elevated, along with pleiotropic Th2 cytokine IL

- 9 

### 29 (associated with bronchial hyperresponsiveness) and pro

- inflammatory IL

- 17, produced 

### 30 by activated T cells. Based on lower inflammat ory, IgE, and cytokine responses in Toll



### 31 like receptor 4 deficient mice, the effects of O 3 seem to be dependent on TLR 4 signaling, 

### 32 as are a number of other biological responses to O 3 according to studies by Hollingsworth 

### 33 et al. ( 2004 ) , Kleeberger et al. ( 2000 ) and Garanziotis et al. ( 2010 ) . The involvement of 

### 34 TLR 4, along with its endogenous ligand, hyaluronan, in O 3 - induced responses described 

### 35 in these studies has been corroborated by a controlled human exposure study by 

### 36 Hernandez et al. ( 2010 ) , who found increased TLR 4 expression and elevated levels of 

### 37 hyaluronic acid in atopic and atopic ast hmatic volunteers exposed to 400 ppb O 3 . This 

### 38 pathway is discussed in more detail in Chapter 5. Examination of dendritic cells (DCs) 

### 39Draft

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- 110 September 2011 from the draining thoracic lymph nodes indicated that O 3 did not enhance the migration 

### 1 of DCs from the lungs to the lymph n odes, nor did it alter the expression of functional 

### 2 DC markers such as CD40, MHC class II, or CD83. However, O 3 did increase expression 

### 3 of CD86, which is generally associated with Th2 responses and is detected at higher 

### 4 levels on DCs from allergic asthmati cs compared to those from healthy donors ( Chen et 

### 5 al., 2006b ) . Increased CD86 has also been observed on airway cells collected from 

### 6 human subjects following exposure to O 3 in studies by Lay et al. ( 2007 ) and Alexis et al. 

### 7 ( 2009 ) , but not Hernandez et al. ( 2010 ) (study details described in Section 6.2.5.4). 

### 8 Ozone exposure during gestation has modest effects on allergy and asthma related 

### 9 endpoints in adult offspring. When dams were exposed to 1.2 ppm O 3 (but not 0.8 ppm) 

### 10 from gestational day 9

- 18, some allergic and inflammatory responses to OVA 

### 11 sensitization and challenge were reduced compared to air exposed controls. This included 

### 12 IgE levels and eosinophils , and was only true of mice that were immunized early in life 

### 13 (PND 3) as opposed to later (PND 42), perhaps due to the proximity of O 3 and antigen 

### 14 exposure. The effects of gestational O 3 exposure on immune function have not been 

### 15 widely studied, and althoug h reductions in allergic endpoints are not generally observed 

### 16 in association with O 3 , other parameters of immune function were found to be reduced, so 

### 17 a more global immunosuppression may underlie these effects. 

### 18 In addition to ozone ’ s pro - allergic effects, it could also make airborne allergens more 

### 19 allergenic. When combined with NO 2 , O 3 has been shown to enhance nitration of 

### 20 common protein allergens, which may increase their allergenicity ( Franze et al., 2005 )

. 

### 21

6.2.7 Hospital Admissions, Emergency Department Visits, and Physician s 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 

### 22 studies, which consisted primarily of time

- series studies conducted in the U.S., Canada, 

### 23 Europe, South America, Australia an d Asia. Upon collectively evaluating the scientific 

### 24 evidence, the 2006 O 3 AQCD concluded that “ the overall evidence supports a causal 

### 25 relationship between acute ambient O 3 exposures and increased respiratory morbidity 

### 26 resulting in increased ED visits and [ hospital admissions] during the warm season ” ( U.S. 

### 27 EPA, 2006b ) . This conclusion is “ strongly supported by the human clinical, animal 

### 28 toxicologic[al], and epidemiologic evidence for [O 3 - induced] lung function decrements, 

### 29 increased respira tory symptoms, airway inflammation, and airway hyperreactivity ” ( U.S. 

### 30 EPA, 2006b )

. 

### 31Draft

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- 111 September 2011 Since the completion of the 2006 O 3 AQCD, relatively fewer studies conducted in the 

### 1 U.S., Canada, and Europe have examined the association between short

- term exposure to 

### 2 ambient O 3 and respiratory hospital admissions and ED visits with a growing number of 

### 3 studies having been conducted in Asia. This section focuses primarily on multicity 

### 4 studies because they examine the effect of O 3 on respiratory

- related h ospital admissions 

### 5 and ED visits over a large geographic area using a consistent statistical methodology. 

### 6 Single

- city studies that encompass a large number of hospital admissions or ED visits, or 

### 7 included a long study

- duration were also evaluated because t hese studies have more 

### 8 power to detect whether an association exists between short

- term O 3 exposure and 

### 9 respiratory hospital admissions and ED visits compared to smaller single

- city studies. 

### 10 Additional single

- city studies were also evaluated within this se ction, if they were 

### 11 conducted in locations not represented by the larger single

- city and multicity studies, or 

### 12 examined population

- specific characteristics not included in the larger studies that may 

### 13 modify the association between short

- term O 3 exposure an d respiratory

- related hospital 

### 14 admissions or ED visits. The remaining single

- city studies identified were not evaluated 

### 15 in this section due to factors such as inadequate study design or insufficient sample size. 

### 16 It should be mentioned that when examining t he association between short

- term O 3 

### 17 exposure and respiratory health effects that require medical attention, it is important to 

### 18 distinguish between hospital admissions and ED visits. This is because it is likely that a 

### 19 small percentage of respiratory ED vi sits will be admitted to the hospital; therefore, 

### 20 respiratory ED visits may represent potentially less serious, but more common outcomes. 

### 21 As a result, in the following sections respiratory hospital admission and ED visit studies 

### 22 are evaluated individually. Additionally, within each section, results are presented as 

### 23 either a collection of respiratory diagnoses or as individual diseases (e.g., asthma, COPD, 

### 24 pneumonia and other respiratory infections) in order to evaluate the potential effect of 

### 25 short

- term O 3 exposure on each respiratory

- related outcome. The ICD codes (i.e., ICD

- 9 

### 26 or ICD

- 10) that encompass each of these endpoints are presented in Table 6

- 25 along 

### 27 with the air quality characteristics of the city, or across all cities, included in each study 

### 28 eval uated in this section. 

### 29Draft

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- 112 September 2011 

### Table 6 - 25 Mean and upper percentile concentrations of respiratory - related hospital admission and emergency department 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 (4 60
- 519) 12 Canadian cities: 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: 8.9
- 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 Admissions: 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 respiratory (460
- 519) 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 Stieb et al. ( 2009 ) 7 Canadian cities Emergency Department 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 Emergency Dep artment 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. ( 2011b ) Atlanta, GA Emergency Department Visits: All respiratory (460
- 466, 477, 480
- 486, 491, 492, 493, 496, 786.09) 8
- h max 1
- h max 24
- h avg Commute Day
- time Night
- time Warm (March
- October): 8
- h max: 53 1
- h max: 62 24
- h avg: 30 Commute: 35 i Day
- time: 45 i Night
- time: 14 i 8
- h max: 75th: 67 Max: 148 1
- h max: 75th: 76 Max: 180 24
- h avg: 75th: 37 Max: 81 Com mute: 75th: 45 Max: 106 Day
time: 75th: 58 Max: 123 Night
time: 75th: 22 Max: 64 Villeneuve et al. ( 2007 ) b Alberta, CAN Emergency Departmen t 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 al. ( 2007b ) New York, NY Emergency Department 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: 33.0Draft

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- 113 September 2011 Study Location Type of Visit (ICD9/10) Averaging Time Mean Concentration (ppb) a Upper Percentile Concentrations (ppb) a Strickland et al. ( 2010 ) Atlanta, GA Emergency Department 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 et al. ( 2009 ) Seattle, WA Emergency Department 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 Emergency Department Visit s: COPD (J40
- 44) 1
- h max 48.8 75th: 61.0 Max: 143.8 Orazzo et al. ( 2009 ) c 6 Italian cities Emergency Department 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: 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 only presented median concentrations.
c Study presented concentrations as μg/m3 Concentration was converted to ppb using the conversion factor of 0.51 assuming stand ard temperature (25°C) and press ure (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 (I CD
- 10
- CA, ICD
- 9, and ICD
- 9
- CM). Attempts were made by the 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 Commute (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 ICD 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. Newly identified studies 

### 3 attempt to further examine the effect of O 3 exposure on respiratory

- related hospital 

### 4 admissions through a multicity design that examines O 3 effect s across countries using a 

### 5Draft

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- 114 September 2011 standardized methodology; multicity studies that examine effects within one country; and 

### 1 multi

- and single

- city studies that attempt to examine potential modifiers of the O 3 - 

### 2 respiratory

- related hospital admission relationship. 

### 3 T he Air Pollution and Health: A European and North American Approach (APHENA) 

### 4 study combined data from existing multicity study databases from Canada, Europe 

### 5 (APHEA2) ( Katsouyanni et al., 2001 ) , and the U.S. (NMMAPS) ( Samet et al., 2000 ) in 

### 6 order to “ develop more reliable estimates of the potential acute effects of air pollution on 

### 7 human health [and] pro vide a common basis for [the] comparison of risks across 

### 8 geographic areas ” ( Katsouyanni et al., 2009 ) . In an attempt to address both of these 

### 9 issues, the investigators conducted extensive sensitivity analyses to evaluate the 

### 10 robustness of the results to different model specifications (e.g., penalized splines [PS] 

### 11 versus natural splines [NS]) and the extent of smoothing to control for seasonal and 

### 12 temporal trends. The trend analyses consisted of subjecting the models to var ying extent 

### 13 of smoothing selected either a priori (e.g., 3 df/year, 8 df/year, and 12 df/year) or by 

### 14 using the absolute sum of the residuals of the partial autocorrelation function (PACF). 

### 15 However, the investigators did not identify the model they deemed t o be the most 

### 16 appropriate for comparing the results across study locations. As a result, when discussing 

### 17 the results across the three study locations below, the 8 df/year results are presented for 

### 18 both the PS and NS models because: (1) 8 df/year is most co nsistent with the extent of 

### 19 temporal adjustment used in previous and recent large multicity studies in the U.S. (e.g., 

### 20 NMMAPS); (2) the risk estimates for 8 df/year and 12 df/year are comparable for all 

### 21 three locations; (3) the models that used the PACF me thod did not report the actual 

### 22 degrees of freedom chosen; and (4) the 3 df/year and the PACF method resulted in 

### 23 negative O 3 risk estimates, which is inconsistent with the results obtained using more 

### 24 aggressive seasonal adjustments. Additionally, when compa ring results across studies in 

### 25 figures, only the results from one of the spline models (e.g., NS) are presented because it 

### 26 has been previously demonstrated that alternative spline models result in relatively 

### 27 similar effect estimates ( HEI, 2003 ) . However, it should be noted that the underlying data 

### 28 and model specifications could result i n varying degrees of bias and precision in effect 

### 29 estimates with different spline models ( Ostro et al., 2006 )

. 

### 30 Katsouyanni et al. ( 2009 ) examined respiratory hospi tal admissions for people aged 

### 31 65 years and older using 1

- h max O 3 data. The extent of hospital admission and O 3 data 

### 32 varied across the 3 datasets: Canadian dataset included 12 cities with data for 3 years 

### 33 (1993

- 1996) per city; European dataset included 8 cities with each city having data for 

### 34 between 2 and 8 years from 1988

- 1997; and U.S. dataset included 14 cities with each city 

### 35 having data for between 4 and 10 years from 1985

- 1994 and 7 cities having only summer 

### 36 O 3 data. The investigators used a three

- sta ge hierarchical model to account for within



### 37 city, within region, and between region variability. Results were presented individually 

### 38Draft

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- 115 September 2011 for each region (Figure 6

- 14; Table 6

- 26). Ozone and PM 10 concentrations were weakly 

### 1 correlated in all locations in the sum mer (r=0.27

- 0.40), but not in the winter. 

### 2 In the Canadian cities, using all

- year data, a 40 ppb increase in 1

- h max O 3 

### 3 concentrations at lag 0

- 1 was associated with an increase in respiratory hospital 

### 4 admissions of 8.9% (95% CI: 0.79, 16.8%) in a PS model and 8.1% (95% CI: 0.24, 

### 5 16.8%) in a NS model ( Katsouyanni et al., 2009 ) . The results were somewhat sensitive to 

### 6 the lag day selected, reduced when using a single

- day lag (e.g., lag 1) (PS: 6.0%; NS: 

### 7 5.5%) and increased when using a distributed lag model (PS: 18.6%; NS: 20.4%). When 

### 8 adjusting for PM 10 , the magnitude of the effect estimate was slightly larger in the NS 

### 9 model (5.1% [95% CI:

- 6.6, 18.6%]) compared to the PS model (3.1% [95% CI:

- 8.3, 

### 10 15.9%]); however, the co pollutant analysis was only conducted using a 1

- day lag. The 

### 11 large confidence intervals for both models could be attributed to the reduction in days 

### 12 included in the copollutant analyses as a result of the every

- 6th

- day PM sampling 

### 13 schedule. When restrictin g the analysis to the summer months, stronger associations were 

### 14 observed between O 3 and respiratory hospital admissions across the lags examined, 

### 15 ranging from ~22 to 37% (the study does not specify whether these effect estimates are 

### 16 from a NS or PS model). Because O 3 concentrations across the cities included in the 

### 17 Canadian dataset (Katsouyanni et al. ( 2009 ) are low (median concentrations ranging from 

### 18 6.7

- 8.3 ppb [Table 6

- 25]), the standardized increment of 40 ppb for a 1

- h ma x increase in 

### 19 O 3 concentrations does not accurately reflect the observed risk of O 3 - related respiratory 

### 20 hospital admissions. Although this increment adequately characterizes the distribution of 

### 21 1

- h max O 3 concentrations across the U.S. and European dataset s, it misrepresents the 

### 22 observed O 3 concentrations in the Canadian dataset. As a result in summary figures, for 

### 23 comparability, effect estimates from the Canadian dataset are presented for both a 5.1 ppb 

### 24 increase in 1

- h max O 3 concentrations (i.e., an appro ximate interquartile range [IQR] 

### 25 increase in O 3 concentrations across the Canadian cities) as well as the standardized 

### 26 increment used throughout the ISA. 

### 27 In Europe, weaker but positive associations were also observed in year round analyses; 

### 28 2.9% (95% CI: 0 .63, 5.0%) in the PS model and 1.6% (95% CI:

- 1.7, 4.2%) in the NS 

### 29 model at lag 0

- 1 for a 40 ppb increase in 1

- h max O 3 concentrations ( Katsouyanni et al., 

### 30 2009 ) . Additionally, at lag 1, associations between O 3 and respir atory hospital admissions 

### 31 were also reduced, but in contrast to the lag 0

- 1 analysis, greater effects were observed in 

### 32 the NS model (2.9% [95% CI: 1.0, 4.9%]) compared to the PS model (1.5% [95% CI:

- 

### 33 2.2, 5.4]). Unlike the Canadian analysis, a distributed lag model provided limited 

### 34 evidence of an association between O 3 and respiratory hospital admissions. To compare 

### 35 with the Canadian results, when adjusting for PM 10 at lag 1, effect estimates were 

### 36 increased in the PS model (2.5% [95% CI: 0.39

- 4.8%]) and rem ained robust in the NS 

### 37 model (2.4% [95% CI: 0.08, 4.6%]). However, the European analysis also examined the 

### 38Draft

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- 116 September 2011 effect of adjusting for PM 10 at lag 0

- 1 and found results were attenuated in both models 

### 1 (PS: 0.8% [95% CI:

- 2.3, 4.0%]; NS: 0.8% [95% CI:

- 1.8, 3.6% ]). Unlike the Canadian 

### 2 and U.S. datasets, the European dataset consisted of daily PM data. The investigators did 

### 3 not observe stronger associations in the summer

- only analyses for the European cities at 

### 4 lag 0

- 1 (PS: 0.4% [95% CI:

- 3.2, 4.0%]; NS: 0.2% [95% CI:

- 3.3, 3.9%]), but did observe 

### 5 some evidence for larger effects during the summer, an ~2.5% increase, at lag 1 in both 

### 6 models (the study does not present the extent of temporal smoothing used for these 

### 7 models). 

### 8

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 ozone concentrations. 

### Figure 6 - 14 Percent increase in respiratory hospital admissions from natural spline models for a 40 ppb increase in 1 - h max ozone concentrations 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 % IncreaseDraft

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- 117 September 2011 

### Table 6 - 26 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
- 1a 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) 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 estimates standardized to 40 ppb for a 1
- h max increase in O 3 concentrations. For the U.S. in year ro und 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 respiratory hospital admissions at lag 0

- 1 for a 40 ppb increase in 1

- h max O 3 

### 3 concentrations with simila r 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 dataset with the PS model (1.1% [95% CI:

- 3.0, 5.3%]), but larger effects in the NS 

### 6 model (3.3% [95% CI: 0.02, 6.8%]), which is consistent with the Canadian results. When 

### 7 adjusting for PM 10 using the U.S. data (i.e., every

- 6th

- day PM data), results were 

### 8 attenuated at lag 0

- 1 (PS: 0.6% [95% CI:

- 2.0, 3.3%]; NS: 1.4% [95% CI:

- 1. 3, 4.2%]) 

### 9 which is consistent with the results presented for the European dataset. However, at lag 1, 

### 10 U.S. risk estimates remained robust to the inclusion of PM 10 in copollutant models as was 

### 11 observed in the Canadian and European datasets. Compared to the all

- year analyses, the 

### 12 investigators did not observe stronger associations in the summer

- only analysis at either 

### 13 lag 0

- 1 (~2.2%) or lag 1 (~2.8%) in both the PS and NS models (the study does not 

### 14 present the extent of temporal smoothing used for these model s). 

### 15 Several additional multicity studies examined respiratory disease hospital admissions in 

### 16 Canada and Europe. Cakmak et al. ( 2006b ) evaluated the association between ambient O 3 

### 17Draft

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- 118 September 2011 concentrations and respir atory hospital admissions for all ages in 10 Canadian cities from 

### 1 April 1993 to March 2000. The primary objective of this study was to examine the 

### 2 potential modification of the effect of ambient air pollution on daily respiratory hospital 

### 3 admissions by edu cation and income using a time

- series analysis conducted at the city



### 4 level. The authors calculated a pooled estimate across cities for each pollutant using a 

### 5 random effects model by first selecting the lag day with the strongest association from the 

### 6 city

- s pecific models. For O 3 , the mean lag day across cities that provided the strongest 

### 7 association and for which the pooled effect estimate was calculated was 1.2 days. In this 

### 8 study, all

- year O 3 concentrations were used in the analysis, and additional seasona l 

### 9 analyses were not conducted. Cakmak et al. ( 2006b ) reported a 4.4% increase (95% CI: 

### 10 2.2, 6.5%) in respiratory hospital admissions for a 20 ppb increase in 24

- h average O 3 

### 11 concentrations. The investigat ors only examined the potential effect of confounding by 

### 12 other pollutants through the use of a multipollutant model (i.e., two or more additional 

### 13 pollutants included in the model), which is difficult to interpret due to the potential 

### 14 multicollinearity betw een pollutants. Cakmak et al. ( 2006b ) also conducted an extensive 

### 15 analysis of potential modifiers, specifically sex, educational attainment, and family 

### 16 income, on the association between air pollution and respiratory hospital admissions. 

### 17 When stratifying by sex, the increase in respiratory hospital admissions due to short

- term 

### 18 O 3 exposure were similar in males (5.2% [95% CI: 3.0, 7.3%]) and females (4.2% [95% 

### 19 CI: 1.8, 6.6%]). In addition, the examination o f effect modification by income found no 

### 20 consistent trend across the quartiles of family income. However, there was evidence that 

### 21 individuals with an education level less than the 9th grade were disproportionately 

### 22 affected by O 3 exposure (4.6% [95% CI: 1.8 , 7.5%]) compared to individuals that 

### 23 completed grades 9

- 13 (1.7% [95% CI:

- 1.9, 5.3%]), some university or trade school 

### 24 (1.4% [95% CI:

- 2.0, 5.1%]), or have a university diploma (0.66% [95% CI:

- 3.3, 4.7%]). 

### 25 The association between O 3 and individuals with an education level less than the 9th 

### 26 grade was the strongest association across all of the pollutants examined. 

### 27 A multicity study conducted in Europe by Biggeri et al. ( 2005 ) examined the association 

### 28 between short

- term O 3 exposure and respiratory hospital admissions for all ages in four 

### 29 Italian cities from 1990 to 1999. In this study, O 3 was only measured duri ng the warm 

### 30 season (May

- September). The authors examined associations between daily respiratory 

### 31 hospital admissions and short

- term O 3 exposure at the city

- level using a time

- series 

### 32 analysis. Pooled estimates were calculated by combining city

- specific estim ates using 

### 33 fixed and random effects models. The investigators found no evidence of an association 

### 34 between O 3 exposure and respiratory hospital admissions in the warm season in both the 

### 35 random (0.1% [95% CI:

- 5.2, 5.7%]; distributed lag 0

- 3) and fixed effec ts (0.1% [95% 

### 36 CI:

- 5.2, 5.7%]; distributed lag 0

- 3) models for a 30 ppb increase in 8

- h max O 3 

### 37 concentrations. 

### 38Draft

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- 119 September 2011 Additional studies examined associations between short

- term O 3 exposure and respiratory 

### 1 hospital admissions specifically in children. In a multicity study conducted in Canada, 

### 2 Dales et al. ( 2006 ) examined the association between all

- year ambient O 3 concentrations 

### 3 and neonatal (ages 0

- 27 days) respiratory hospital admissions in 11 Canadian cities from 

### 4 1986 to 2000. The investigators used a statistical analysis approach similar to Cakmak et 

### 5 al. ( 2006b ) (i.e., time

- series analysis to examine city

- specific associations, and then a 

### 6 random effects model to pool estimates across cities). The authors reported that for O 3, 

### 7 the mean lag day across cities that provided the strongest association was 2 days. The 

### 8 authors reported a 5.4% (95% CI: 2.9, 8.0%) increase in neonatal respiratory hospital 

### 9 admissions for a 20 ppb increase in 24

- h avg O 3 concentrations at lag

- 2 days. The results 

### 10 from Dales et al. ( 2006 ) provide support for the associations observed in a smaller scale 

### 11 study that examined O 3 exposure and pediatric respiratory hospital admissions in 

### 12 New York st ate ( Lin et al., 2008a ) . Lin et al. ( 2008a ) observed a positive association 

### 13 betw een O 3 and pediatric (i.e., <18 years) respiratory admissions at lag 2 (results not 

### 14 presented quantitatively) in a two

- stage Bayesian hierarchical model analysis of 11 

### 15 geographic regions of New York from 1991 to 2001. 

### 16 Overall, the evidence from epidemiolo gic studies continues to support an association 

### 17 between short

- term O 3 exposure and respiratory

- related hospital admissions, but it 

### 18 remains unclear whether certain factors (individual

- or population

- level) modify this 

### 19 association. Wong et al. ( 2009 ) examined the potential modification of the relationship 

### 20 between ambient O 3 (along with NO 2 , SO 2 , and PM 10 ) and respiratory hospital 

### 21 admissions by influenza intensity in Hong Kong for the period 1996

– 2002. Influenza 

### 22 intensity was defined as a continuous variable using the proportion of weekly specimens 

### 23 positive for influenza A or B instead of defining influenza epidemics. This approach was 

### 24 used to avoid any potential bias associated with the unpredictable seasonality of influenza 

### 25 in Hong Kong ( Wong et al., 2009 ) . In models that examined the baseline effect (i.e., 

### 26 without tak ing into consideration influenza intensity) of short

- term O 3 exposure, the 

### 27 authors found a 3.6% (95% CI: 1.9, 5.3%) and 3.2% (95% CI: 1.0, 5.4%) increase in 

### 28 respiratory hospital admissions at lag 0

- 1 for a 30 ppb increase in 8

- h max O 3 

### 29 concentrations for t he all age and ≥ 65 age groups, respectively. When examining 

### 30 influenza intensity, Wong et al. ( 2009 ) reported that the association between short

- term 

### 31 exposure to O 3 and respiratory hospital admissions was stronger with higher levels of 

### 32 influenza intensity: additional increase in respiratory hospital admissions above baseline 

### 33 of 1.4% (95% CI: 0.24, 2.6%) for all age groups and 2.4% (95% CI: 0.94, 3.8%) for those 

### 34 65 and older when influenza activity increased from 0% to 10%. No difference in effects 

### 35 was observed when stratifying by sex. 

### 36Draft

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- 120 September 2011 Cause - Specific Respiratory Outcomes In the 2006 O 3 AQCD a limited numb er of studies were identified that examined the 

### 1 effect of short

- term O 3 exposure on cause - specific respiratory hospital admissions. The 

### 2 limited evidence “ reported positive O 3 associations with... asthma and COPD, 

### 3 especially... during the summer or warm season ” ( U.S. EPA, 2006b ) . Of the studies 

### 4 evaluated since the completion of the 2006 O 3 AQCD, more have focused on identifying 

### 5 whether O 3 exposure is associated with specific respiratory

- related hospital admissions, 

### 6 including COPD, pneumonia, a nd asthma, but the overall body of evidence remains 

### 7 small. 

### 8 Chronic Obstructive Pulmonary Disease Medina

- Ramon et al. ( 2006 ) examined the association between short

- term exposure to 

### 9 ambient O 3 and PM 10 concentrations and Medicare hospital admissions among 

### 10 individuals ≥ 65 years of age for COPD in 35 cities in the U.S. for the years 1986

- 1999. 

### 11 The cities included in this analysis were selected because they monitored PM 10 on a daily 

### 12 basis. In this study, city

- specific results were obtained using a monthly time

- stratified 

### 13 case - crossover analysis. A meta

- analysis was then conducted usin g random effects 

### 14 models to combine the city

- specific results. All cities measured O 3 from May through 

### 15 September, while only 16 of the cities had year

- round measurements. The authors 

### 16 reported a 1.6% increase (95% CI: 0.48, 2.9%) in COPD admissions for lag 0

- 1 in the 

### 17 warm season for a 30 ppb increase in 8

- h max O 3 concentrations. When examining 

### 18 single

- day lags, stronger associations were observed for lag 1 (2.9% [95% CI: 1.8, 4.0%]) 

### 19 compared to lag 0 (

- 1.5% [95% CI:

- 2.7,

- 0.24%]). The authors found no eviden ce of 

### 20 associations in cool season (

- 1.9% [95% CI:

- 3.6,

- 0.06%]; lag 0

- 1) or year round (0.24% 

### 21 [95% CI:

- 0.78, 1.2%]; lag 0

- 1) analyses. In a copollutant model using warm season data, 

### 22 the association between O 3 and COPD hospital admissions was robust to th e inclusion of 

### 23 PM 10 in the model (results not presented quantitatively). The authors conducted 

### 24 additional analyses to examine potential modification of the warm season estimates for 

### 25 O 3 and COPD admissions by several city

- level characteristics: percentage l iving in 

### 26 poverty, emphysema mortality rate (as an indication of smoking), daily summer apparent 

### 27 temperature, and percentage of households using central air conditioning. Of the city



### 28 level characteristics examined, stronger associations were only reported f or cities with a 

### 29 larger variability in daily apparent summer temperature. 

### 30 In a single

- city study conducted in Vancouver from 1994

- 1998, a location with low 

### 31 ambient O 3 concentrations (Table 6

- 25), Yang et al. ( 2005b ) examined the association 

### 32 between O 3 and COPD. Ozone was moderately inversely correlated with CO (r=

- 0.56), 

### 33 NO 2 (r=

- 0.32), and SO 2 (r=

- 0.34), and weakly inversely correlated with PM 10 (r=

- 0.09), 

### 34 suggesting that the observed O 3 effect is likely not only due to a positive correlation with 

### 35Draft

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- 121 September 2011 othe r pollutants. Yang et al. ( 2005b ) examined 1

- to 7

- day (e.g., (0

- 6 days) lagged 

### 1 moving averages and observed an 8.8% (95% CI:

- 12.5, 32.6%) increase in COPD 

### 2 admissions for lag 0

- 3 per 20 ppb increase in 24

- h avg O 3 concentrations. In two



### 3 pollutant models at lag 0

- 3, O 3 effect estimates were robust to the i nclusion of NO 2 , SO 2 , 

### 4 and PM 10 in the model, but were increased slightly when adding CO (Figure 6

- 20; Table 

### 5 6

- 28). 

### 6 Pneumonia In addition to COPD, Medina

- Ramon et al. ( 2006 ) examined the association between 

### 7 short

- term exposure to ambient O 3 and PM 10 concentrations and Medicare hospital 

### 8 admissions among individuals ≥ 65 years of ag e for pneumonia (ICD

- 9: 480

- 487). The 

### 9 authors reported an increase in pneumonia hospital admissions in the warm season (2.5% 

### 10 [95% CI: 1.6, 3.5%] for a 30 ppb increase in 8

- h max O 3 concentrations; lag 0

- 1). Similar 

### 11 to the results observed for COPD hospital admissions, pneumonia hospital admissions 

### 12 associations were stronger at lag 1 (2.6% [95% CI: 1.8, 3.4%]) compared to lag 0 (0.06% 

### 13 [95% CI:

- 0.72, 0.78%]), and no evidence of an association was observed in the cool 

### 14 season or year round. In two

- pollutant mo dels, the association between O 3 exposure and 

### 15 pneumonia hospital admissions was robust to the inclusion of PM 10 (results not presented 

### 16 quantitatively). The authors also examined potential effect modification of the warm 

### 17 season estimates for O 3 - related pneu monia hospital admissions, as was done for COPD, 

### 18 by several city

- level characteristics. Stronger associations were reported in cities with a 

### 19 lower percentage of central air conditioning use. Across the cities examined, the 

### 20 percentage of households having c entral air conditioning ranged from 6 to 93%. The 

### 21 authors found no evidence of effect modification of the O 3 - pneumonia hospital admission 

### 22 relationship when examining the other city

- level characteristics. 

### 23 Results from a single

- city study conducted in Boston did not support the results presented 

### 24 by Medina

- Ramon et al. ( 2006 ) . Zanobe tti and Schwartz ( 2006 ) examined the association 

### 25 of O 3 and pneumonia Medicare hospital admissions for the period 1995

- 1999. Ozone was 

### 26 weakly positively correlated with PM 2.5 (r=0.20) and weakly inversely correlated with 

### 27 black carbon, NO 2 , and CO (

- 0.2 5,

- 0.14, and

- 0.30, respectively). In an all

- year analysis, 

### 28 the investigators reported a 3.8% (95% CI:

- 7.9,

- 0.1%) decrease in pneumonia 

### 29 admissions for a 20 ppb increase in 24

- h average O 3 concentrations at lag 0 and a 6.0% 

### 30 (95% CI:

- 11.1,

- 1.4%) decreas e for the average of lags 0 and 1. It should be noted that 

### 31 the mean daily counts of pneumonia admissions was low for this study, ~14 admissions 

### 32 per day compared to ~271 admissions per day for Medina

- Ramon et al. ( 2006 ) . However, 

### 33 in analyses with other pollutants Zanobetti and Schwartz ( 2006 ) did observe pos itive 

### 34 associations with pneumonia hospital admissions, indicating that the low number of daily 

### 35Draft

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- 122 September 2011 hospital admission counts probably did not influence the O 3 - pneumonia hospital 

### 1 admissions association in this study. . 

### 2 Asthma There are relatively fewer studies that examined the association between short

- term 

### 3 exposure to O 3 and asthma hospital admissions, presumably due to the limited power 

### 4 given the relative rarity of asthma hospital admissions compared to ED or physician 

### 5 visits. A study from New York City exami ned the association of 8

- h max O 3 

### 6 concentrations with severe acute asthma admissions (i.e., those admitted to the Intensive 

### 7 Care Unit [ICU]) during the warm season in the years 1999 through 2006 ( Silverman and 

### 8 Ito, 2010 ) . In this study, O 3 was moderately correlated with PM 10 (r=0.59). When 

### 9 stratifying by age, the investigators reported positive associations with ICU asthma 

### 10 admissions for the 6

- to 18

- year age group (26.8% [95% CI: 1.4, 58.2%] for a 30 ppb 

### 11 increase in maximum 8

- h avg O 3 concentrations at lag 0

- 1), but little evidence of 

### 12 associations for the other age groups examined (<6 years, 19

- 49, 50+, and all ages). 

### 13 However, positive associations were observed for each age

- stratified group and all ages 

### 14 for non

- ICU asthma admissions, but again the strongest association was reported for the 

### 15 6

- to 18

- ye ars age group (28.2% [95% CI: 15.3, 41.5%]; lag 0

- 1). In two

- pollutant 

### 16 models, O 3 effect estimates for both non

- ICU and ICU hospital admissions remained 

### 17 robust to adjustment for PM 2.5 . In an additional analysis, using a smooth function, the 

### 18 authors examine d whether the shape of the C

- R curve for O 3 and asthma hospital 

### 19 admissions (i.e., both general and ICU for all ages) is linear. To account for the potential 

### 20 confounding effects of PM 2.5 , Silverman and Ito ( 2010 ) also included a smooth function 

### 21 of PM 2.5 lag 0

- 1. When comparing the curve to a linear fit li ne the authors found that the 

### 22 linear fit is a reasonable approximation of the concentration

- response relationship 

### 23 between O 3 and asthma hospital admissions around and below the level of the current 

### 24 NAAQS (Figure 6

- 15). 

### 25Draft

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- 123 September 2011 Source: Used with permission from American Academy of Allergy, Asthma & Immunology ( Silverman and Ito, 2010 )

. The average of 0 day and 1 day lagged 8
- h ozone was used in a two
- pollutant model with PM 2.5 lag 0
- 1, adjusting for temporal 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 s ample size. 

### Figure 6 - 15 Estimated relative risks (RRs) of ozone - related asthma hospital admissions allowing for possible nonlinear relationships using natural splines. Averting Behavior The studies discussed above have found consistent positive association s between short



### 1 term O 3 exposure and respiratory

- related hospital admissions, however, the strength of 

### 2 these associations may be underestimated due to the studies not accounting for averting 

### 3 behavior. As discussed in Section 4.6.4, recent studies by Neidel l ( 2009 ) and Neidell and 

### 4 Kinney ( 2010 ) conducted in Souther California 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 concentrations there was an increase in asthma 

### 8 hospital admissions. Alth ough only a few epidemiologic studies have examined averting 

### 9 behavior and these studies are limited to asthma hospital admissions, they do provide 

### 10 preliminary evidence indicating that epidemiologic studies may underestimate 

### 11Draft

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- 124 September 2011 associations between O 3 exposure and health effects by not accounting for behaviorial 

### 1 modification when public health alerts are issued. 

### 2

6.2.7.3 Emergency Department Visit Studies Overall, relatively fewer studies have examined the association between short

- term O 3 

### 3 exposure and respiratory

- rela ted ED visits, compared to hospital admissions. In the 2006 

### 4 O 3 AQCD, positive, but inconsistent, associations were observed between O 3 and 

### 5 respiratory

- related ED visits with effects generally occurring during the warm season. 

### 6 Since the completion of the pr evious AQCD, larger studies have been conducted, in 

### 7 terms of sample size, study duration, and in some cases multiple cities, to examine the 

### 8 association between O 3 and ED visits for all respiratory diseases, COPD, and asthma. 

### 9 Respiratory Disease A large si ngle

- city study conducted in Atlanta, by Tolbert et al. ( 2007 ) , and subsequently 

### 10 reanalyzed by Darrow et al. ( 2011b ) , provides evidence for an association between short



### 11 term exposures to ambient O 3 concentrations and respiratory ED visits. Tolbert et al. 

### 12 ( 2007 ) examined the association between air pollution, both gaseous pollutants and PM 

### 13 and its compone nts, and respiratory disease ED visits in all ages from 1993 to 2004. The 

### 14 correlations between O 3 and the other pollutants examined ranged from 0.2 for CO and 

### 15 SO 2 to 0.5

- 0.6 for the PM measures. Using an a priori average of lags 0

- 2 for each air 

### 16 pollutant examined, the authors reported a 3.9% (95% CI: 2.7, 5.2%) increase in 

### 17 respiratory ED visits for a 30 ppb increase in 8

- h max O 3 concentrations during the warm 

### 18 season [defined as March

- October in Darrow et al. ( 2011b ) ]. In copollutant models, the 

### 19 O 3 associations with respiratory ED visits remai ned robust with CO, NO 2 , and PM 10 

### 20 (results not presented quantitatively). 

### 21 Darrow et al. ( 2011b ) examined the same data as Tolbert et al. ( 2007 ) , but explored 

### 22 whether differences exist in the assoc iation between O 3 exposure and respiratory

- related 

### 23 ED visits depending on the exposure metric used (i.e., 8

- h max, 1

- h max, 24

- h average, 

### 24 commuting period [7:00 a.m. to 10:00 a.m.; 4:00 p.m. to 7:00 p.m.], day

- time [8:00 a.m. 

### 25 to 7:00 p.m.] and night

- time [ 12:00 a.m. to 6:00 a.m.]). To examine the association 

### 26 between the various O 3 exposure metrics and respiratory ED visits, the authors used a 

### 27 time

- stratified case

- crossover approach, selecting control days as those days within the 

### 28 same calendar month and max imum temperature as the case day. Darrow et al. ( 2011b ) 

### 29 found at lag 1, the results were somewhat variable across exposure metrics. The strongest 

### 30 associations with respiratory ED visits were found when using the 8

- h max, 1

- h max, and 

### 31 day

- time exposure metrics with weaker associations using the 24

- h avg and commuting 

### 32Draft

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- 125 September 2011 period exposure metrics; a negative association was observed when using the night

- time 

### 1 exposure metric (Figure 6

- 16). 

### 2

Source: Used with permission from Nature Publishing Group ( Darrow et al., 2011b )

. 

### Figure 6 - 16 Risk ratio for respiratory ED visits and different ozone exposure metrics in Atlanta from 1993 - 2004.
In an additional study conducted in 6 Italian cities, Orazzo et al. ( 2009 ) examined 

### 3 respiratory ED visits for ages 0

- 2 years in 6 Italian cities from 1996 to 2000. However, 

### 4 instead of identify ing respiratory ED visits using the traditional approach of selecting 

### 5 ICD codes as was done by Tolbert et al. ( 2007 ) and Darrow et al. ( 2011b ) , Orazzo et al. 

### 6 ( 2009 ) used data on wheeze extracted from medical records as an indicator of lower 

### 7 respiratory disease. This study examined daily counts of wheeze in relation to air 

### 8 pollution using a time

- stratified case

- crossover approach in which control days were 

### 9 matched on day of week in the s ame month and year as the case day. The authors found 

### 10 no evidence of an association between 8

- h max O 3 concentrations and respiratory ED 

### 11 visits in children aged 0

- 2 years in models that examined both single

- day lags and 

### 12 moving averages of lags from 0

- 6 day s in year

- round and seasonal analyses (i.e., warm 

### 13Draft

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- 126 September 2011 and cool seasons). In all

- year analyses, the percent increase in total wheeze ranged from

- 

### 1 1.4% to

- 3.3% for a 0

- 1 to 0

- 6 day lag, respectively. 

### 2 COPD Stieb et al. ( 2009 ) also examined the association between short

- term O 3 exposure and 

### 3 COPD ED visits in 7 Canadian cities. Across cities, in an all

- year analysis, O 3 was found 

### 4 to be positively associated with COPD ED visits (4.0% [95% CI:

- 0.54, 8.6%] at lag 2 for 

### 5 a 20 ppb increase in 24

- h avg O 3 concentrations). In seasonal analyses, larger effects 

### 6 were observed between O 3 and COPD ED visits during the warm season (i.e., April



### 7 September) 6.8% [95% CI: 0.11, 13.9%] (lag day not specified); with no associations 

### 8 observed in the winter season. Stieb et al. ( 2009 ) also examined associations between 

### 9 respiratory

- related ED visits, including COP D, and air pollution at sub

- daily time scales 

### 10 (i.e., 3

- h avg of ED visits versus 3

- h avg pollutant concentrations) and found no evidence 

### 11 of consistent associations between any pollutant and any respiratory outcome. 

### 12 In a single

- city study, Arbex et al. ( 2009 ) examined the association between COPD and 

### 13 several ambient air pollutants, including O 3 , in Sao Paulo, Brazil for the years 2001

- 2003 

### 14 for individuals over the age of 40. Associations between O 3 exposure and COPD ED 

### 15 visits were examined in both single

- day l ag (0

- 6 days) and polynomial distributed lag 

### 16 models (0

- 6 days). In all

- year analyses, O 3 was not found to be associated with an 

### 17 increase in COPD ED visits (results not presented quantitatively). The authors also 

### 18 conducted stratified analyses to examine the potential modification of the air pollutant



### 19 COPD ED visits relationship by age (e.g., 40

- 64, >64) and sex. In these analyses O 3 was 

### 20 found to have an increase in COPD ED visits for women, but not for men or either of the 

### 21 age groups examined. 

### 22 Asthma In a s tudy of 7 Canadian cities, Stieb et al. ( 2009 ) also examined the association between 

### 23 exposure to air pollution (i.e., CO, NO 2 , O 3 , SO 2 , PM 10 , PM 2.5 , and O 3 ) and asthma ED 

### 24 visits. Associations between short

- term O 3 exposure and asthma ED visits were examined 

### 25 at the city level and then pooled using either fixed or random effects models depending 

### 26 on whether heterogeneity among effect estimates was found to be statistically significant. 

### 27 Across cities, in an all

- year analysis, the authors found that short

- term O 3 exposure was 

### 28 associated with a positive increase (3.5% [95% CI: 0.33, 6.8%] at lag 2 for a 20 ppb 

### 29 increase in 24

- h avg O 3 concentrations) in asthma ED visits. The au thors did not present 

### 30 the results from seasonal analyses for asthma, but state that no associations were 

### 31 observed between any pollutant and respiratory ED visits in the winter season. As stated 

### 32 previously, in analyses of 3

- h avg O 3 concentrations, the auth ors observed no evidence of 

### 33 consistent associations between any pollutant and any respiratory outcome, including 

### 34Draft

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- 127 September 2011 asthma. A single

- city study conducted in Alberta, Canada ( Villeneuve et al., 2007 ) from 

### 1 1992

- 2002 among individuals two years of age and older provides additional support for 

### 2 the findings from Stieb et al. ( 2009 ) , but also attempts to identify those lifestages (i.e., 2

- 

### 3 4, 5

- 14, 15

- 44, 45

- 64, 65

- 74, or 75+) most susceptible to O 3 - induced asthma ED visits. In 

### 4 a time

- referent case

- crossover analysis, Villeneuve et al. found an increase in asthma ED 

### 5 visits in an all

- year analysis across all ages (12.0% [95% CI: 6.8, 17.2] for a 30 ppb 

### 6 increase in max 8

- h avg O 3 concentrations at lag 0

- 2) with associations being stronger 

### 7 during the warmer months (19.0% [95% CI: 11.9, 28.1]). When stratifying by age, th e 

### 8 strongest associations were observed in the warm season for individuals 5

- 14 (28.1% 

### 9 [95% CI: 11.9, 45.1]; lag 0

- 2) and 15

- 44 (19.0% [95% CI: 8.5, 31.8]; lag 0

- 2). These 

### 10 associations were not found to be confounded by the inclusion of aeroallergens in age



### 11 specific models. 

### 12 Several additional single

- city studies have also provided evidence of an association 

### 13 between asthma ED visits and ambient O 3 concentrations. Ito et al. ( 2007b ) examined the 

### 14 association between short

- term exposure to air pollution and asthma ED visits for all ages 

### 15 in New York City from 1999 to 2002. Ito et al. ( 2007b ) used three different weather 

### 16 models with varying extent of smoothing to account for temporal relationships and 

### 17 multicollinearity among pollutants and meteorological variables (i.e., temperature and 

### 18 dew point) to examine the effect of model selection on th e air pollutant

- asthma ED visit 

### 19 relationship. When examining O 3 , the authors reported a positive association with asthma 

### 20 ED visits, during the warm season across the models (ranging from 8.6 to 16.9%) and an 

### 21 inverse association in the cool season (ranging from

- 23.4 to

- 25.1%), at lag 0

- 1 for a 30 

### 22 ppb increase in 8

- h max O 3 concentrations. Using a simplified version of the weather 

### 23 model used in NMMAPS analyses (i.e., terms for same

- day temperature and 1

- 3 day 

### 24 average temperature), Ito et al. ( 2007b ) found that O 3 effects were not substantially 

### 25 changed in copollutant mode ls with PM 2.5 , NO 2 , SO 2 , and CO during the warm season 

### 26 (Figure 6

- 19; Table 6

- 27). 

### 27Draft

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- 128 September 2011 Source: Used with permission from American Thoracic Society ( Strickland et al., 2010 )

. The reference for the rate ratio is the estimated rate at the 5th percentile of the poll utant concentration. Estimates are presented for the 5th percentile through the 95th percentile of pollutant concentrations due to instability in the dose
- response estimates at the distribution tails. 

### Figure 6 - 17 Loess dose - response estimates and twice - sta ndard error estimates from generalized additive models for associations between 3 - day avg ozone concentrations and ED visits for pediatric asthma.

Strickland et al. ( 2010 ) examined the association between O 3 exposure and pediatric 

### 1 asthma ED visits (ages 5

- 17 yea rs) in Atlanta between 1993 and 2004 using the same air 

### 2 quality data as Darrow et al. ( 2011b ) and Tolbert et al. ( 2007 ) . However, unlike Darrow 

### 3 et al. ( 2011b ) and Tolbert et al. ( 2007 ) , which used single centrally located monitors or an 

### 4 average of monitors, respectively, Strickland et al. ( 2010 ) used population

- weighting to 

### 5 combine daily pollutant concentrations across monitors. In this study, the authors 

### 6 developed a statistical model using hospital

- specific time

- series data that is essentially 

### 7 equivalent to a time

- stratified case

- crossover analysis (i.e., using interaction terms 

### 8 between year, month, and day

- of

- week to mimic the approach of selectin g referent days 

### 9 within the same month and year as the case day). The authors observed a 6.4% (95% CI: 

### 10 3.2, 9.6%) increase in ED visits for a 30 ppb increase in 8

- h max O 3 concentrations at lag 

### 11 0

- 2 in an all

- year analysis. In seasonal analyses, stronger ass ociations were observed 

### 12 during the warm season (i.e., May

- October) (8.4% [95% CI: 4.4, 12.7%]; lag 0

- 2) than 

### 13 the cold season (4.5% [95% CI:

- 0.82, 10.0%]; lag 0

- 2). Strickland et al. ( 2011 ) 

### 14 confirmed these findings in an additional analysis using t he same dataset, and found that 

### 15 the metric used to assign exposure (i.e., centrally located monitor, unweighted average 

### 16Draft

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- 129 September 2011 across monitors, and population

- weighted average across monitors) did not influence 

### 1 pediatric asthma ED visit risk estimates for spatial ly homogeneous pollutants such as O 3 . 

### 2 In copollutant analyses, Strickland et al. ( 2010 ) found that O 3 effect estimates were not 

### 3 substantially changed when controlling for other pollutants (CO, NO 2 , PM 2.5 elemental 

### 4 carbon, PM 2.5 sulfate) (results not presented qua ntitatively). The authors also examined 

### 5 the C

- R relationship between O 3 exposure and pediatric asthma ED visits and found that 

### 6 both quintile and loess dose

- response analyses (Figure 6

- 17) suggest that there are 

### 7 elevated associations with O 3 at concentratio ns as low as 30 ppb. These dose

- response 

### 8 analyses do not provide evidence of a threshold level. 

### 9 In a single

- city study conducted on the West coast, Mar and Koenig ( 2009 ) examined the 

### 10 association between O 3 exposure and asthma ED visits (ICD

- 9 codes_ 493

- 493.9) for 

### 11 children (< 18) and adults (≥ 18) in Seattle, WA from 1998 to 2002. Of the total number 

### 12 of visits over the study duration, 64% of visits in the age group < 18 c omprised boys, and 

### 13 70% of visits in the ≥ 18 age group comprised females. Mar and Koenig ( 2009 ) 

### 14 conducted a time

- series analysis using both 1

- h max and max 8

- h avg O 3 concentrations. 

### 15 Although a similar pattern of associations was observed using both metrics, only those 

### 16 results using the max 8

- h avg O 3 metric are discussed here since they are more applicable 

### 17 to the current O 3 NAAQS. Mar and Koenig ( 2009 ) presented results for single day lags of 

### 18 0 to 5 days, but found consistent positive associations across individual lag days which 

### 19 supports the findings from the studies discussed above that examined multi

- day 

### 20 exposures. For children, con sistent positive associations were observed across all lags, 

### 21 ranging from a 19.1

- 36.8% increase in asthma ED visits for a 30 ppb increase in 8

- h max 

### 22 O 3 concentrations with the strongest associations observed at lag 0 (33.1% [95% CI: 3.0, 

### 23 68.5]) and lag 3 ( 36.8% [95% CI: 6.1, 77.2]) (Figure x). O 3 was also found to be 

### 24 positively associated with asthma ED visits for adults at all lags, ranging from 9.3

- 26.0%, 

### 25 except at lag 0 (Figure 6

- 18). The slightly different lag times for children and adults 

### 26 suggest that children may be more immediately responsive to O 3 exposures than adults 

### 27 ( Mar and Koenig, 2009 )

. 

### 28Draft

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- 130 September 2011 Adapted from Mar and Koenig ( 2009 )

. 

### Figure 6 - 18 Relative risk of asthma ED visits children and adults for a 30 ppb increase in max 8 - h avg O3 concentrations in Seattle, WA, 1998 - 2002.

Respiratory Infection Although an increasing number of studies have examined the association between O 3 

### 1 exposure and cause

- specific respiratory ED visits this trend has not included an extensive 

### 2 examination of the association between O 3 exposure and respiratory infection ED visits. 

### 3 Stieb et al. ( 2009 ) also examined the association between short

- term O 3 exposure and 

### 4 respiratory infection ED visits in 7 Canadian cities. In an all

- year analysis, there was no 

### 5 evidence of an association between O 3 exposure and respiratory inf ection ED visits at all 

### 6 lags examined (i.e., 0, 1, and 2). Across cities, respiratory infections comprised the single 

### 7 largest diagnostic category, approximately 32%, of all the ED visits examined, which 

### 8 also included myocardial infarction, heart failure, d ysrhythmia, asthma, and COPD. 

### 9 Lag 0

Lag 1

Lag 2

Lag 3

Lag 4

Lag 5

0.80 1.00 1.20 1.40 1.60 1.80 Relative Risk Black = Children Red = AdultsDraft

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- 131 September 2011 

### 6.2.7.4 Outpatient and Physician Visit Studies
Several studies have examined the association between ambient O 3 concentrations and 

### 1 physician or outpatient (non

- hospital, non

- ED) visits for acute conditions in various 

### 2 geographic locati ons. Burra et al. ( 2009 ) examined asthma physician visits among 

### 3 patients aged 1

- 17 and 18

- 64 years in Toronto, Cana da from 1992 to 2001. The authors 

### 4 found little or no evidence of an association between asthma physician visits and O 3 ; 

### 5 however, seasonal analyses were not conducted. It should be noted that in this study, 

### 6 most of the relative risks for O 3 were less than o ne and statistically significant, perhaps 

### 7 indicating an inverse correlation with another pollutant or an artifact of the strong 

### 8 seasonality of asthma visits. Villeneuve et al. ( 2006b ) also focused on physician visits to 

### 9 examine the effect of short

- term O 3 exposure on allergic rhinitis among individuals aged 

### 10 65 or older in Toronto from 1995 to 2000. The autho rs did not observe any evidence of 

### 11 an association between allergic rhinitis physician visits and ambient O 3 concentrations in 

### 12 single

- day lag models in an all

- year analysis (results not presented quantitatively). 

### 13 In a study conducted in Atlanta, Sinclair et al. ( 2010 ) examined the association of acute 

### 14 asthma and respiratory infection (e.g., upper respiratory infections and lower r espiratory 

### 15 infections) outpatient visits from a managed care organization with ambient O 3 

### 16 concentrations as well as multiple PM size fractions and species from August 1998 

### 17 through December 2002. The authors separated the analysis into two time periods (the 

### 18 first 25 months of the study period and the second 28 months of the study period), in 

### 19 order to compare the air pollutant concentrations and relationships between air pollutants 

### 20 and acute respiratory visits for the 25

- month time

- period examined in Sinclair et al. 

### 21 ( 2004 ) to an additional 28

- month time

- period of available data from the Atlanta Aerosol 

### 22 Research Inhalation Epidemi ology Study (ARIES). The authors found little evidence of 

### 23 an association between O 3 and asthma visits, for both children and adults, or respiratory 

### 24 infection visits in all

- year analyses and seasonal analyses. For example, a slightly 

### 25 elevated relative risk (RR) for childhood asthma visits was observed during the 25

- month 

### 26 period in the cold season (RR: 1.12 [95% CI: 0.86, 1.41]; lag 0

- 2 for a 30 ppb increase in 

### 27 8

- h max O 3 ), but not in the warm season (RR: 0.97 [95% CI: 0.86, 1.10]; lag 0

- 2). During 

### 28 the 28

- mon th period at lag 0

- 2, a slightly larger positive effect was observed during the 

### 29 warm season (RR: 1.06 [95% CI: 0.97, 1.17]), compared to the cold season (RR: 1.03 

### 30 [95% CI: 0.87, 1.21]). Overall, these results contradict those from Strickland et al. ( 2010 ) 

### 31 discussed above. Although the mean number of asthma visits and O 3 concentrations in 

### 32 Sinclair et al. ( 2010 ) and Strickland et al. ( 2010 ) are similar the difference in results 

### 33 bet ween the two studies could be attributed to the severity of O 3 - induced asthma 

### 34 exacerbations (i.e., more severe symptoms requiring a visit to a hospital) and behavior, 

### 35 such as delaying a visit to the doctor for less severe symptoms. 

### 36Draft

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- 132 September 2011 

### 6.2.7.5 Summary
The results of the recent studies evaluated largely support the conclusion of the 2006 O 3 

### 1 AQCD. While fewer studies were published overall since the previous rev iew, several 

### 2 multicity studies (e.g., Cakmak et al., 2006b ; Dales et al., 2006 ) and a multi

- continent 

### 3 stu dy ( Katsouyanni et al., 2009 ) provide supporting evidence for an association between 

### 4 short

- term O 3 exposure and an increase in respiratory

- related hospital admissions and ED 

### 5 visits. Collectively, in the studies evaluated, both single

- city and multicity, there is 

### 6 continued evidence for increases in both hospital admissions and ED visits when 

### 7 examining all respiratory outcomes combined. Additionally, new studies support an 

### 8 association between short

- term O 3 exposure and asthm a ( Strickland et al., 2010 ; Stieb et 

### 9 al., 2009 ) and COPD ( Stieb et al., 2009 ; Medina

- Ramon et al., 2006 ) hospital admissions 

### 10 and ED visits, with more limited evidence for pneumonia hospital admissions and ED 

### 11 visits ( Medina

- Ramon et al., 2006 ; Zanobetti and Schwartz, 2006 ) . In seasonal analyses, 

### 12 stronger associations were observed in the warm season or sum mer months compared to 

### 13 the cold season, particularly for asthma ( Strickland et al., 2010 ; Ito et al., 2007b ) and 

### 14 COPD ( Medina

- Ramon et al., 2006 ) (Figure 6

- 19; Table 6

- 27), which is consistent with 

### 15 the conclusions of the 2006 O 3 AQCD. There is also continued evidence that children are 

### 16 particularly susceptible to O 3 - induced respi ratory effects ( Silverman and Ito, 2010 ; 

### 17 Strickland et al., 2010 ; Mar and Koenig, 2009 ; Villeneuve et al., 2007 ; Dales et al., 

### 18 2006 ) . Altho ugh the collective evidence indicates a consistent positive association 

### 19 between O 3 exposure and respiratory

- related hospital admissions and ED visits, the 

### 20 magnitude of these associations may be underestimated due to behavioral modification in 

### 21 response to f orecasted air quality ( Neidell and Kinney, 2010 ; Neidell, 2009 ) 

### 22 (Section 4.6.4). 

### 23 Additional studies that focused on respiratory

- related outpatient or physician visits found 

### 24 no evidence of an association with short

- term O 3 exposure, but this could be attributed to 

### 25 the severity of O 3 - induced respiratory effects requiring more immediate treatment o r 

### 26 behavioral factors that result in delayed visits to a physician. 

### 27 The studies that examined the potential confounding effects of copollutants found that O 3 

### 28 effect estimates remained relatively robust upon the inclusion of PM and gaseous 

### 29 pollutants in two

- pollutant models (Figure 6

- 19; Table 6

- 27), including ( Strickland et al., 

### 30 2010 ; Tolbert et al., 2007 ; Medina

- Ramon et al., 2006 ) , which did not present results 

### 31 quantitatively. These findings are consistent with the studies evaluated in the 2006 O 3 

### 32 AQCD ( U.S. EPA, 2006b ) (Figure 7

- 12, p. 7

- 80) which found O 3 respiratory hospital 

### 33 admissions risk estimates remained robust to the inclusio n of PM in copollutant models. 

### 34Draft

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- 133 September 2011 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. Effect estimates are for a 20 ppb increase in 24 hours; 30 ppb increase in 8
- h max; and 40 increase in 1
- h max ozone concentrations. HA=hospital admission; ED=emergency department. Black=All
- year analysis; Red=Summer only analysis; Blue=Winter only analysis. 

### Figure 6 - 19 Perc ent increase in respiratory - related hospital admission and ED visits in studies that presented all - year and/or seasonal results. Study Wong et al. (2009; 196722) Cakmak et al. (2006; 93272) Dales et al. (2006; 90744) Orazzo et al. (2009, 202800)a Katsouyanni et al. (2009; 199899) Katsouyanni et al. (2009; 199899)b Darrow et al. (2009; 202800) Tolbert et al. (2007, 090316) Biggeri et al. (2005; 87395)c Katsouyanni et al. (2009; 199899) Katsouyanni et al. (2009; 199899)b Stieb et al. (2009; 195858) Villeneuve et al. (2007; 195859) Strickland et al. (2010; 624878) Silverman and Ito (2010; 386252)d Ito et al. (2007; 156594) Villeneuve et al. (2007; 195859) Mar and Koenig (2009; 594410) Strickland et al. (2010; 624878) Silverman and Ito (2010; 386252)d Mar and Koenig (2009; 594410) Ito et al. (2007; 156594) Villeneuve et al. (2007; 195859) Strickland et al. (2010; 624878) Stieb et al. (2009; 195858) Medina

- Ramon et al. (2006; 87721) Yang et al. (2006; 90184) Stieb et al. (2009; 195858)e Medina

- Ramon et al. (2006; 87721) Medina

Zanobetti and Schwartz (2006; 90195) Medina

- Ramon et al. (2006; 87721) Medina

- Medina

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 7 Canadian Cities

36 U.S. cities Vancouver 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 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)

1 0

- 2 0

- 3 0

- 1 0

- 1 DL (0

- 2) DL (0

- 2)

2 0

- 2 0

- 2 0

- 1 0

- 1 0

- 2 2 0

- 2 0

- 1 0 0

- 1 0

- 2 0

- 2 2 0

- 1 0

- 3 NR 0

- 1 0

- 1 0

- 1 0

- 1 0

- 1 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 ED HA HA ED HA HA HA HA HA HA

- 25

- 20

- 15

- 10

- 5 0 5 10 15 20 25 30 35 40 % IncreaseDraft

– Do Not Cite or Quote 6
- 134 September 2011 

### Table 6 - 27 Corresponding Effect Estimates for Figure 6 - 19
Study ED Visit or Hospital Admission Location Age Lag Avg Time % In crease (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. ( 2011b ) 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. ( 2011b ) 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) Katsouyanni 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 Seattl e, 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 Seattl e, WA < 18 0 8
- h max 33.1 (3.00, 68.5)

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 (
- 0.5 4, 8.62) Medina
- Ramon et al. ( 2006 ) Hospital Admission 36 U.S. citi es 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 6 5+ 0
- 1 8
- h max 1.63 (0.48, 2.85)

Cold Medina
- Ramon et al. ( 2006 ) Hosp ital Admission 36 U.S. cities 65+ 0
- 1 8
- h max
- 1.85 (
- 3.60,
- 0.06)Draft

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- 135 September 2011 Study ED Visit or Hospital Admission Location Age Lag Avg Time % In crease (95% CI) 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 Admission 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 Admissio n 36 U.S. cities 65+ 0
- 1 8
- h max
- 4.88 (
- 6.59,
- 3.14)

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.

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 ozone concentrations. An “ a ” represents studies that examined hospital admissions, “ b ” represents a study that examined ED visits, and “ c ” represents risk estimates from APHENA
- Canada standardized to an approximate IQR of 5.1 ppb for a 1
- h max increase in ozone 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 models with SO 2 . 

### Figure 6 - 20 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; 199899)a

Yang et al. (2006; 90184)a

Ito et al. (2007; 156594)b

- 10

- 5 0 5 10 15 20 25 30 % IncreaseDraft

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- 136 September 2011 

### Table 6 - 28 Corresponding effect estimates for Figure 6 - 20

Study a Location Visit Type Age Lag Copollutant % Inc rease (95% CI) All - year Respiratory Katsouyanni et al. ( 2009 ) APHENA
- U.S. HA 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 ) Vancouver HA 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)
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 concentrations. Additionally, a preliminary examination of the C

- R relationship found no evidence of a 

### 1 threshold between short

- term O 3 exposure and pediatric asthma ED visits ( Silverman and 

### 2 Ito, 2010 ; Strickland et al., 2010 ) . Overall, the new body of evidence supports an 

### 3 association between short

- term O 3 exposure and respiratory

- related hospital admissions 

### 4 and ED visits, with additional evidence for stronger associations during the warm season 

### 5 for specific respiratory outcomes such as asthma and COPD. 

### 6

6.2.8 Respiratory Mortality The epidemiologic, controlled human exposure, and toxicological studies discussed 

### 7 within this section (Section 6.2) provides evidence for multiple respiratory effects in 

### 8 response to short

- term O 3 exposure. Additionally, the evidence from experimental studies 

### 9 indicates multi ple potential pathways of O 3 - induced respiratory effects, which support the 

### 10 continuum of respiratory effects that could potentially result in respiratory

- related 

### 11 mortality. The 2006 O 3 AQCD found inconsistent evidence for an association between 

### 12 short

- term O 3 exposure and respiratory mortality ( U.S. EPA, 2006b ) . Although some 

### 13 studies reported a strong positive association between O 3 exposure and respiratory 

### 14Draft

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- 137 September 2011 mortality, additional studies reported a small association or no association. Recen t 

### 1 multicity studies found consistent positive associations between short

- term O 3 exposure 

### 2 and respiratory mortality, specifically during the summer months. 

### 3 The APHENA study, described earlier in Section 6.2.7.2, ( Katsouyann i et al., 2009 ) also 

### 4 examined associations between short

- term O 3 exposure and mortality and found 

### 5 consistent positive associations for respiratory mortality in all

- year analyses with stronger 

### 6 associations in analyses restricted to the summer season. Additional multicity studies 

### 7 from the U.S. ( Zanobetti and Schwartz, 2008b ) , Europe ( Samoli et al., 2009 ) , Italy 

### 8 ( Stafoggia et al., 2010 ) , and Asia ( Wong et al., 2010 ) that conducted summer season 

### 9 and/or all

- year analyses provide additional support for an association between short

- term 

### 10 O 3 exposure and respiratory mortality (Figure 6

- 37). 

### 11 Of the studies evaluated, only the APHENA study ( Katsouyanni et al., 2009 ) and the 

### 12 Italian multicity study ( Stafoggia et al., 2010 ) conducted an analysis of the potenti al for 

### 13 copollutant confounding of the O 3 - respiratory mortality relationship. In the APHENA 

### 14 study, in the European dataset, when focusing on the natural spline model with 8 df/year 

### 15 (as discussed in Section 6.2.7.2) and lag 1 results (as discussed in Section 6.6.2.1), 

### 16 respiratory mortality risk estimates were robust to the inclusion of PM 10 in copollutant 

### 17 models in all

- year analyses with O 3 respiratory mortality risk estimates increasing in the 

### 18 Canadian and U.S. datasets. In summer season analyses, respirator y O 3 mortality risk 

### 19 estimates were robust in the U.S. dataset and attenuated in the European dataset. 

### 20 Similarly, in the Italian multicity study ( Stafoggia et al., 2010 ) , which was limited to the 

### 21 summer season, respiratory mortality risk estimates were attenuated in copollutant 

### 22 models with PM 10 . Based on the APHENA and Italian multicity results, O 3 respiratory 

### 23 mortality risk estimates appear to be moderately to substantia lly sensitive (e.g., increased 

### 24 or attenuated) to inclusion of PM 10 . However, in the APHENA study, the mostly every



### 25 6th

- day sampling schedule for PM 10 in the Canadian and U.S. datasets greatly reduced 

### 26 their sample size and limits the interpretation of these results. 

### 27

6.2.9 Summary and Causal Determination
The 2006 O 3 AQCD concluded that there was clear, consistent evidence of a causal 

### 28 relationship between short

- term O 3 exposure and respiratory effects ( U.S. EPA, 2006b )

. 

### 29 This conclusion was subst antiated by evidence from controlled human exposure and 

### 30 toxicological studies indicating a range of respiratory effects in response to short

- term O 3 

### 31 exposure, including pulmonary function decrements, respiratory symptoms, lung 

### 32 inflammation, increased lung permeability, and airway hyperresponsiveness. 

### 33 Toxicological studies provided additional evidence for O 3 - induced impairment of host 

### 34Draft

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- 138 September 2011 defenses. Combined, these findings from experimental studies provided support for 

### 1 epidemiologic evidence, in which short

- term O 3 exposure was consistently associated 

### 2 with decreases in lung function in populations with increased outdoor exposures, children 

### 3 with asthma, and healthy children; increases in respiratory symptoms and asthma 

### 4 medication use in children with asthma; and i ncreases in respiratory

- related hospital 

### 5 admissions and asthma

- related ED visits. Short

- term O 3 exposure also was consistently 

### 6 associated with all

- cause and cardiopulmonary mortality; however, the contribution of 

### 7 respiratory causes to these findings was un certain. 

### 8 Building on the large body of evidence presented in the 2006 O 3 AQCD, recent studies 

### 9 support associations between short

- term O 3 exposure and respiratory effects. Controlled 

### 10 human exposure studies continue to provide the strongest evidence for lung function 

### 11 decrements in young healthy adults over a range of O 3 concentrations. Studies previously 

### 12 reported mean O 3 - induced FEV 1 decrements of 6

- 8% at 80 ppb O 3 ( Adams, 2006a , 

### 13 2003a ; McDonnell et al., 1991 ; Horstman et al., 1990 ) , and new evidence additionally 

### 14 indicates mean FEV 1 decrements of 6% at 70 ppb O 3 ( Schelegle et al., 2009 ) and 2

- 3% at 

### 15 60 ppb O 3 ( Kim et al., 2011 ; Brown et al., 2008 ; Adams, 2006a ) (Section 6.2.1.1). In 

### 16 healthy young adults, O 3 - induced decrements in FEV 1 do not appear to depend on gender 

### 17 ( Hazucha et al., 2003 ) , body surface area or height ( McDonnell et a l., 1997 ) , lung size or 

### 18 baseline FVC ( Messineo and Adams, 1990 ) . There is limited evidence that blacks may 

### 19 experience greater O 3 - induced decrements in FEV 1 than do age

- matched whites ( Que et 

### 20 al. ; Seal et al., 1993 ) . Healthy children experience similar spirometric responses but 

### 21 lesse r symptoms from O 3 exposure relative to young adults ( McDonnell et al., 1985b )

. 

### 22 On average, spirometric and symptom responses to O 3 exposure appear to decline with 

### 23 increasing age beyond about 18 years of age ( McDonnell et al., 1999 ; Seal et al., 1996 )

. 

### 24 There is also a tendency for slightly increased spirometric responses in mild asthm atics 

### 25 and allergic rhinitics relative to healthy young adults ( Jorres et al., 1996 ) . Spirometric 

### 26 responses in asthmatics appear to be affected by baseline lung function, i.e., responses 

### 27 increase with disease severity ( Horstman et al., 1995 )

. 

### 28 Available information from controlled human exposure studies on recovery from O 3 

### 29 exposure indicates that an initial phase of recovery in healthy individuals proceeds 

### 30 relatively rapidly, with acute spirometric and symptom responses resolving within abo ut 

### 31 2 to 4 h ( Folinsbee and Hazucha, 1989 ) . Small residual lung function effects are alm ost 

### 32 completely resolved within 24 h. Effects of O 3 on the small airways persisting a day 

### 33 following exposure, assessed by persistent decrement in FEF 25

- 75 and altered ventilation 

### 34 distribution, may be due in part to inflammation ( Frank et al., 2001 ; Foster et al., 1997 )

. 

### 35 In more responsive individuals, this recove ry in lung function takes longer (as much as 

### 36 48 hours) to return to baseline. Some cellular responses may not return to baseline levels 

### 37 in humans for more than 10

- 20 days following O 3 exposure ( Devli n et al., 1997 ) . Airway 

### 38Draft

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- 139 September 2011 hyperresponsiveness and increased epithelial permeability are also observed as late as 24 

### 1 h postexposure ( Que et al. )

. 

### 2 With repeated O 3 exposures over several days, spirometric and symptom responses 

### 3 become attenuated in both healthy individuals and asthmatics, but this tolerance is lost 

### 4 after about a week without exposure ( Gong et al., 1997a ; Folinsbee et al., 1994 ; Kulle et 

### 5 al., 1982 ) . Airway respons iveness also appears to be somewhat attenuated with repeated 

### 6 O 3 exposures in healthy individuals, but becomes increased in individuals with 

### 7 preexisting allergic airway disease ( Gong et al., 1997a ; Folinsbee et al., 1994 ) . Some 

### 8 indicators of pulmonary inflammation are attenuated with repeated O 3 exposures. 

### 9 However, other markers such as epithelial integrity and damage do not show attenuation, 

### 10 suggesting continued tissue damage during repeated O 3 exposure ( Devlin et al., 1997 )

. 

### 11 Collectively, epidemiologic evidence supports observations from controlled human 

### 12 exposure studies of O 3 - induced decrements in lung function (Section 6.2.1.2). A notable 

### 13 difference among newer studi es was the relatively limited investigation of the effect of 

### 14 ambient O 3 exposure on lung function in populations engaged in outdoor recreation, 

### 15 exercise, or work, which contributed to the weight of evidence in previous AQCDs. As in 

### 16 previous AQCDs, recent e pidemiologic investigation focused on and most consistently 

### 17 demonstrated associations between increases in ambient O 3 exposure and decreases in 

### 18 lung function in children with asthma. Across the diverse populations examined in 

### 19 epidemiologic studies, ambient O 3 exposure was associated with 1

- 8% decreases in mean 

### 20 lung function per standardized increment in O 3 concentration 1 . Larger decreases (3

- 8%) 

### 21 were observed in children with asthma with increased outdoor exposures, CS use, or 

### 22 concurrent URI and older adults with airway hyperresponsiveness, elevated BMI, or 

### 23 GSTP1 Val/Val genotype, indicating the existence of groups within the population with 

### 24 potentially increased sensitivity to O 3 exposure. Further, several epidemiologic studies 

### 25 found that O 3 - associated decreases in lung function were associated with concomitant 

### 26 increases in respiratory symptoms. Biological plausibility for O 3 - associated decrements 

### 27 in lung function in controlled human exposure, epidemiologic, and animal studies is 

### 28 provided by the well

- do cumented effects of O 3 activating bronchial C

- fibers (Section 

### 29 5.3.2). 

### 30 Across disciplines, studies have examined factors that may potentially increase an 

### 31 individual ’ s susceptibility to O 3 - induced decrements in lung function. In the controlled 

### 32 human exposure studies, there is a large degree of intersubject variability in lung function 

### 33 decrements, symptomatic responses, pulmonary inflammation, airway 

### 34 hyperresponsiveness, and altered epithelial permeability in healthy adults exposed to O 3 

### 35

1 Effect estimates were standardized to a 40
- ppb increase for 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

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- 140 September 2011 ( Que et al. ; Holz et al., 2005 ; McDonnell, 1996 ) . The magnitude of pulmonary 

### 1 inflammation, airway hyperresponsiveness, and increas es in epithelial permeability do 

### 2 not appear to be correlated, nor are these responses to O 3 correlated with changes in lung 

### 3 function, suggesting that different mechanisms may be responsible for these processes 

### 4 ( Que et al. ; Balmes et al., 1997 ; Balmes et al., 1996 ; Aris et al., 1995 ) . However, these 

### 5 responses tend to be reproducible within a given individual over a period of several 

### 6 months indicating differences in the intrinsic responsiveness of individuals ( Holz et al., 

### 7 2005 ; Hazucha et al., 2003 ; Holz et al., 1999 ; McDonnell et al., 1985a ) . Numerous 

### 8 reasons for differences in the suscep tibility of individuals to O 3 exposure have been 

### 9 reported in the literature. Dosimetric and mechanistic considerations are discussed in 

### 10 Section 5.4. Evidence in all three disciplines suggests a role for antioxidant defenses in 

### 11 modulating respiratory respon ses to O 3 . The biological plausibility of these findings is 

### 12 provided by the well

- characterized evidence for O 3 exposure leading to the formation of 

### 13 secondary oxidation products, which subsequently activate neural reflexes that mediate 

### 14 lung function decreme nts (Section 5.3.2). Secondary oxidation products also initiate 

### 15 pulmonary inflammation (Sections 5.3.3). Epidemiologic studies additionally have found 

### 16 that atopy ( Khatri et al., 2009 ) , concurrent respiratory infection ( Lewis et al., 2005 ) , 

### 17 AHR, and elevated BMI ( Alexeeff et al., 2007 ) may modify respiratory responses to O 3 

### 18 exposure (Section 6.2.1.2). Retrospective analyses of controlled human exposure studies 

### 19 of data pooled across 15 controlled human exposure stud ies also show larger O 3 - induced 

### 20 FEV 1 decrements in adults with higher BMI ( McDonnell et al., 2010 ; Bennett et al., 

### 21 2007 )

. 

### 22 Additional respiratory effects induced by short

- term O 3 exposures in controlled human 

### 23 exposure studies of healthy, young adults include increases in respiratory symptoms with 

### 24 O 3 concentrations <80 ppb ( Schelegle et al., 2009 ; Adams, 2006a ) (Section 6.2.1.1). 

### 25 Similarly, epidemiologic studies collectively demonstrate that increases in short

- term 

### 26 ambient O 3 exposure are associated with increases in respiratory symptoms and asthma 

### 27 medication use among subjects with asthma (Section 6.2.4.1). Among recent 

### 28 epidemiologic studies, the strongest evidence of O 3 - associated respiratory symptoms was 

### 29 found in populations with multiple potential susceptibility factors, specifically, 

### 30 individuals with asthma and atopy ( Khatri et al., 2009 ; Escamilla

- Nuñez et al., 2008 ; Feo 

### 31 Brito et al., 2007 ) and children with asthma with diminished antioxidant enzyme activity 

### 32 ( Romieu et al., 2006 )

. 

### 33 Recent controlled human exposure studies (Section 6.2.3.1) and toxicological studies 

### 34 (Sect ion 6.2.3.3) also continue to demonstrate lung injury and inflammatory responses 

### 35 upon O 3 exposure. Evidence from more than a hundred toxicological studies clearly 

### 36 indicates that O 3 induces damage and inflammation in the lung, and studies continue to 

### 37Draft

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- 141 September 2011 elucid ate the mechanistic pathways involved (Section 5.3). Though inflammation may 

### 1 resolve, continued inflammation may alter the Janetrita2010 

### 2 structure and function of pulmonary tissues. New controlled human studies support 

### 3 previous findings for pulmonary infla mmation at 60 ppb O 3 , the lowest concentration 

### 4 evaluated . Building on the extensive experimental evidence, epidemiologic studies 

### 5 provide new evidence for ambient O 3 - associated increases in pulmonary inflammation in 

### 6 individuals with asthma. These associati ons were observed primarily for 8

- h max or 8

- h 

### 7 average O 3 exposures but for both same

- day and multiday average exposures. Multiple 

### 8 studies examined and found increases in eNO ( Berhane et al., 2011 ; Khatri et al., 2009 ; 

### 9 Barraza

- Villarreal et al., 2008 ) . The clinical significance of these findings was supported 

### 10 by observations of concomitant O 3 - associated increase s in respiratory symptoms ( Khatri 

### 11 et al., 2009 ; Barraza

- Villarreal et al., 2008 ) . A smaller number of studie s examined and 

### 12 found associations with cytokines such as IL

- 6 or IL

- 8 in nasal lavage samples ( Barraza



### 13 Villarreal et al., 2008 ; Sienra

- Monge et al., 2004 ) inflammatory cells in blood (e.g., 

### 14 eosinophils) ( Khatri et al., 2009 ) , decreased levels of antioxidants ( Sienra

- Monge et al., 

### 15 2004 ) , and increased levels of indicators of oxidative stress ( Romieu et al., 2008 ) 

### 16 (Section 6.2.3.2). 

### 17 Modification of innate and adaptive immunity is emerging as a mechanistic pathway 

### 18 underlying the effects of ozone on asthma and allergic air ways disease (Section 5.3.6). 

### 19 While the majority of evidence comes from animal studies, results from controlled 

### 20 human exposure studies suggest that these pathways may be relevant to humans and may 

### 21 lead to the induction and exacerbation of asthma ( Alexis et al., 2010 ; Hernandez et al., 

### 22 2010 ; Alexis et al., 2009 ; Bosson et al., 2003 ) . Further, differences between asthmatics 

### 23 and healthy controls in ozone

- mediated innate and adaptive immune responses have been 

### 24 noted (Section 5.4.2.2). 

### 25 The subclinical and overt respiratory effects observed across disciplines collectively 

### 26 provide support for epidemiologic studies that demonstrate consistently positive 

### 27 associations of short

- term O 3 exposure with respiratory

- related hospital admissions and 

### 28 ED visits (Section 6.2.7). Consistent with evidence presented in the 2006 O 3 AQCD, new 

### 29 multicity studies and a multicontinent study (i.e., APHENA) ( Katsouyanni et al., 2009 ) 

### 30 found risk estimates ranging from an approximate 1.6 to 5.4% increase in all respiratory



### 31 related hospital ad missions and ED visits in all

- year analyses for standardized increases 

### 32 in ambient O 3 concentrations 1 . Positive associations persisted in analyses restricted to the 

### 33 summer season, but the magnitude varied depending on the study location (Figure 6

- 19). 

### 34 Compa red with studies reviewed in the 2006 O 3 AQCD, a larger number of recent studies 

### 35

1 Effect estimates were standardized to a 20
- ppb increase for 24
- h avg O 3 , a 30
- ppb increase for 8
- h max O 3 , and a 40
- ppb increase for 1
- h max O 3 .Draft

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- 142 September 2011 examined hospital admissions and ED visits for specific respiratory outcomes. Although 

### 1 still limited in number, both single

- and multicity studies found consistent, positive 

### 2 a ssociations between short

- term O 3 exposures and asthma and COPD hospital admissions 

### 3 and ED visits, with more limited evidence for pneumonia. Consistent with the 

### 4 conclusions of the 2006 O 3 AQCD, in studies that conducted seasonal analyses, risk 

### 5 estimates we re elevated in the warm season compared to cold season or all

- season 

### 6 analyses, specifically for asthma and COPD. Although recent studies did not include 

### 7 detailed age

- stratified results, the increased risk of asthma hospital admissions 

### 8 ( Silverman a nd Ito, 2010 ; Strickland et al., 2010 ; Dales et al., 2006 ) observed for children 

### 9 strengthens the conclusion from the 2006 O 3 AQCD that children are particularly 

### 10 susceptible to O 3 - induced respiratory effects ( U.S. EPA, 2006b ) . Although the 

### 11 concentration

- response relationship has not been extensively examined, preliminary 

### 12 examinations found no evidence of a threshold between short

- term O 3 exposure and 

### 13 asthma hospital admissions and pediatric asthma ED visits ( Silverman and Ito, 2010 ; 

### 14 Strickland et al., 2010 )

. 

### 15 New evidence extends the potential range of well

- established O 3 - associated respiratory 

### 16 effects by demonstrating associations between short

- term ambient O 3 exposu re and 

### 17 respiratory

- related mortality. In all

- year analyses, a multicontinent (APHENA) and 

### 18 multicity (PAPA) study found consistent, positive associations with respiratory mortality 

### 19 for all ages but less consistent evidence in analyses restricted to ages 75+ . Further, 

### 20 multicity studies in the U.S. and Europe that conducted seasonal analyses found stronger 

### 21 associations during the summer season (Section 6.2.8). 

### 22 Several studies of respiratory morbidity and mortality evaluated the potential 

### 23 confounding effects o f copollutants, in particular, PM 10 , PM 2.5 , or NO 2 . In most cases, 

### 24 effect estimates remained robust to the inclusion of copollutants; however, in several 

### 25 studies, changes were observed in the magnitude of the O 3 association. In studies of lung 

### 26 function and respiratory symptoms, larger effects frequently were estimated for O 3 when 

### 27 copollutants were added to models. Ozone effect estimates for respiratory

- related hospital 

### 28 admissions and ED visits remained relatively robust upon the inclusion of PM and 

### 29 gaseous pollutants in two

- pollutant models ( Strickland et al., 2010 ; Tolbert et al., 2007 ; 

### 30 Medina

- Ramon et al., 2006 ) . Although copollutant confounding was not extensively 

### 31 examined in mortality studies, the O 3 - respiratory mortality relationship was moderately 

### 32 to substantially sensitive (e.g., increased or attenuated) to the inclusion of PM 10 in 

### 33 copollutant models ( Stafoggia et al., 2010 ; Katsouyanni et al., 2009 ) . However, 

### 34 interpretation of these results requires caution due to the limited PM datasets used in 

### 35 these studies. Together, these findings across respiratory endpoints provide support for 

### 36 the independent effects of short

- term ambient O 3 exposures. 

### 37Draft

– Do Not Cite or Quote 6
- 143 September 2011 In summary, new studies evaluated since the completion of the 2006 O 3 AQCD support 

### 1 and expand upon the strong body of evidence that indicated a causal relationship between 

### 2 short

- term O 3 exposure and respiratory health effects. Ne w controlled human exposure 

### 3 studies continue to demonstrate O 3 - induced decreases in FEV 1 and pulmonary 

### 4 inflammation at concentrations as low as 60 ppb. New epidemiologic studies provide 

### 5 evidence for associations of ambient O 3 exposure with biological marke rs of pulmonary 

### 6 inflammation and oxidative stress. Toxicological studies have continued to support the 

### 7 biological plausibility for the O 3 - induced respiratory effects observed in the controlled 

### 8 human exposure and epidemiologic studies. Additionally, recent epidemiologic studies 

### 9 further confirm that respiratory morbidity and mortality associations are stronger during 

### 10 the warm/summer months and remain relatively robust after adjustment for copollutants. 

### 11 However, despite the consistency of association between s hort

- term O 3 exposure and 

### 12 respiratory effects, new evidence suggests that the magnitude of association may be 

### 13 underestimated due to behavioral modification in response to forecasted air quality 

### 14 (Section 4.6.4). Collectively, the new evidence integrated acr oss toxicological, controlled 

### 15 human exposure, and epidemiologic studies, in conjunction with that reviewed in 

### 16 previous AQCDs, is sufficient to conclude that there is a causal relationship between 

### 17 short - term O 3 exposure and respiratory health effects. 

### 18


## 6.3 Cardi ovascular Effects

6.3.1 Controlled Human Exposure
O 3 reacts rapidly on contact with respiratory system tissue and is not absorbed or 

### 19 transported to extrapulmonary sites to any significant degree as such. Controlled human 

### 20 exposure studies discussed in the previous AQCDs failed to demonstrate any consistent 

### 21 extrapulmonary effects. Some controlled human exposure studies have attempted to 

### 22 identify specific markers of exposure to O 3 in blood. Foster et al. ( 1996 ) found a 

### 23 reduction in the serum levels of the free radical scavenger α

- tocopherol after O 3 exposure. 

### 24 Liu et al. ( 1999 ; 1997 ) used a salicylate metabolite, 2,3, dehydroxybenzoic acid (DHBA), 

### 25 to indicate increased levels of hydroxyl radical which hydroxylates salicylate to DHBA. 

### 26 Increased DHBA levels after exposure to 120 and 400 ppb suggest that O 3 increases 

### 27 productio n of hydroxyl radical. The levels of DHBA were correlated with changes in 

### 28 spirometry. 

### 29 Gong et al. ( 1998 ) observed a small, statistically significant O 3 - induced increase in the 

### 30 alveolar

- to

- arterial PO 2 gradient in both healthy (n = 6) and hypertensive (n = 10) adult 

### 31 males (aged 4 1

- 78 years) exposed for 3 hours with exercise to 300 ppb O 3 . The 

### 32Draft

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- 144 September 2011 mechanism for the decrease in arterial oxygen tension in the Gong et al. ( 1998 ) study 

### 1 could be due to an O 3 - induced ventilation

- perfusion mismatch. Gong et al. ( 1998 ) 

### 2 suggested that by impairing alveolar

- arterial oxygen transfer, the O 3 ex posure could 

### 3 potentially lead to adverse cardiac events by decreasing oxygen supply to the 

### 4 myocardium. The subjects in the Gong et al. ( 1998 ) study had sufficient functional 

### 5 reserve so as to not experience significant ECG changes or myocardial ischemia and/or 

### 6 injury. In studies e valuating the exercise performance of healthy adults, no significant 

### 7 effect of O 3 on arterial O 2 saturation has been observed ( Schelegle and Adams, 1986 )

. 

### 8 More recently, Fakhri et al. ( 2009 ) evaluated changes in HRV among adult volunteers 

### 9 (n=50; 27 ± 7 years) during 2

- h exposures to PM 2.5 CAPs (127±62 μg/m 3 ) and O 3 

### 10 (114±7 ppb), alone and in combination. High frequency HRV was increased following 

### 11 CAPs

- only (p=0.046) and O 3 - only (p=0.051) exposures, but not in combination. The 

### 12 standard deviation of NN intervals and the square root of the mean squared differences of 

### 13 su ccessive NN intervals also showed marginally significant (0.05<p<0.10) effect due to 

### 14 O 3 but not CAPS. Diastolic blood pressure increased by 2 mmHg following the combined 

### 15 O 3 + CAPs exposure, but was not altered by either O 3 or CAPs alone. Ten of the subject s 

### 16 in this study were characterized as “ mildly ” asthmatic, however, asthmatic status was not 

### 17 found to modify these effects. For a subset of the subjects without asthma in the Fakhri et 

### 18 al. ( 20 09 ) study, Urch et al. ( 2005 ) previously reported a 6 mmHg increase in diastolic 

### 19 blood pressure following a 2

- h resting exposur e to O 3 (120 ppb) + PM 2.5 CAPs (150 

### 20 μg/m 3 ) in healthy adults (n=23; 32 ± 107 years), which was statistically different from the 

### 21 1 mmHg increase seen following FA exposure. 

### 22

6.3.2 Epidemiology
The 2006 O 3 AQCD concluded that the “ generally limited body of evidence is highly 

### 23 suggestive that O 3 directly and/or indirectly contributes to cardiovascular

- related 

### 24 morbidity, ” including physiologic effects (e.g., release of platelet activating factor 

### 25 [PAF]), HRV, arrhythmias, and myocardial infarctions, although the availab le body of 

### 26 evidence reviewed during the 2006 O 3 AQCD does not “ fully substantiate links between 

### 27 ambient O 3 exposure and adverse cardiovascular outcomes ” ( U.S. EPA, 2006b ) . Since 

### 28 the completion of the 2006 O 3 AQCD an increasing number of studies have examined the 

### 29 relationship between short

- term O 3 exposure and cardiovascular morbidity and mortality. 

### 30 These new studies, as well as evidence from the previous AQCDs, are presented within 

### 31 this section. 

### 32Draft

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- 145 September 2011 

### 6.3.2.1 Arrhythmia
In the 2006 O 3 AQCD, conflictin g results were observed when examining the effect of O 3 

### 1 on arrhythmias ( Dockery et al., 2005 ; Rich et al., 2005 ) . A study by Dockery et al. ( 2005 ) 

### 2 reported no association between O 3 levels and ventricular arrhythmia s among patients 

### 3 with implantable cardioverter defibrillators (ICD) living in Boston, MA, although when 

### 4 O 3 was categorized into quintiles, there was weak evidence of an association with 

### 5 increasing O 3 concentration (median O 3 concentration: 22.9 ppb). Rich et al. ( 2005 ) 

### 6 performed a re

- analysis of this cohort using a case

- crossover design and detected a 

### 7 positive association between O 3 exposure and ventricular arrhythmias. Recent studies 

### 8 were conducted in various locations and each used a different cardiac episode to define 

### 9 an arrhythmic event and a different time period of exposure, which may help explain 

### 10 observed differences across studies. Ozone levels for each new study are reported in 

### 11 Table 6

- 29. 

### 12

Table 6 - 29 Characterization of ozone concentrations (in ppb) from studies of arrhythmias

` Reference Location Averaging Time Mean Concentration (Standard Deviation) Upper Range of Concentration Anderson et al. ( 201 0 ) London, England 8
- h max 8.08 75th: 11.5 Metzger et al. ( 2007 ) Atlanta, GA 8
- h max Summer only 53.9 (23) Max: 148
Rich et al. ( 2006a ) St. Louis, MO 24
- h 21* 75th: 31 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 Sarnat et al. ( 2006a ) 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 *Median presented (information on mean not given). Multiple studies examined O 3 - related effects on individuals with ICDs. One study of 518 

### 13 ICD patients who had at least 1 tachyarrythmia within a 10

- year period (totaling 6287 

### 14 tachyarrhythmic event

- days; 1993

- 2002) was conducted in Atlanta, Georgia ( Metzger et 

### 15 al., 2007 ) . Tachyarrhythmic events were defined as any ventricular tachyarrhythmic 

### 16 event, any ventr icular tachyarrhythmic event that resulted in electrical therapy, and any 

### 17 ventricular tachyarrhythmic event that resulted in defibrillation. In the primary analysis, 

### 18 no evidence of an association was observed for a 30 ppb increase in 8

- h max O 3 

### 19 concentrati ons and tachyarrhythmic events (OR: 1.00 [95% CI: 0.92, 1.08]; lag 0). 

### 20 Season

- specific as well as several sensitivity analyses (including the use of an 

### 21Draft

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- 146 September 2011 unconstrained distributed lag model [lags 0

- 6]) were conducted resulting in similar null 

### 1 associations. A strength of this study is that it incorporated a large sample size over a 

### 2 long time period. 

### 3 In a case

- crossover analysis, a population of ICD patients in Boston, previously examined 

### 4 by ( Rich et al., 2005 ) was used to assess the association between air pollution and 

### 5 paroxysmal atrial fibrillation (PAF) episodes ( Rich et al., 2006b ) . In addition to 

### 6 ventricular arrhythmias, ICD devices may also detect supraven tricular arrhythmias, of 

### 7 which atrial fibrillation is the most common. Although atrial fibrillation is generally not 

### 8 considered lethal, it has been associated with increased premature mortality as well as 

### 9 hospitalization and stroke. Ninety

- one electrophysi ologist

- confirmed episodes of PAF 

### 10 were ascertained among 29 patients. An association (OR: 3.86 [95% CI: 1.44, 10.28] per 

### 11 40 ppb increase in 1

- h max O 3 concentrations) was observed between increases in O 3 

### 12 during the concurrent hour and PAF episodes (lag 0

- h ). The estimated OR for the 24

- h 

### 13 moving average concentration was elevated (OR: 1.81 [95% CI: 0.86, 3.83] per 20 ppb), 

### 14 but weaker than the estimate for the shorter exposure window. The association between 

### 15 PAF and O 3 in the concurrent hour during the cold m onths was comparable to that during 

### 16 the warm months. In addition, no evidence of a deviation from linearity between O 3 

### 17 concentration and the log odds of PAF was observed. Authors report that the difference 

### 18 between O 3 exposure and observed effect between this study (PAF and 1

- h O 3 ) and their 

### 19 previous study (ventricular arrhythmias and 24

- h moving average O 3 ) ( Rich et al., 2005 ) 

### 20 suggest a more rapid response to air pollution for PAF ( Rich et al., 2006b )

. 

### 21 In an additional study, Rich et al. ( 2006a ) employed a case

- crossover design to examine 

### 22 the association between air pollution and 139 confirmed ventricular arrhythmias among 

### 23 56 ICD patients in St Louis, Missouri. The authors observed a positive association with 

### 24 O 3 (OR: 1.17 [95% CI: 0.58, 2.38] per 20 ppb increase in 24

- h moving avg O 3 

### 25 concentrations [lags 0

- 23 hours]). Although the authors concluded these results were 

### 26 similar to their results from Boston ( Rich et al., 2005 ) , they postulated that the pollutants 

### 27 responsible for the increased risk in ventricular arrhythmias are different (O 3 and PM 2.5 in 

### 28 Boston and sulfur dioxide in St Louis). 

### 29 Anderson et al. ( 2010 ) used a case

- crossover framework to assess air pollution and 

### 30 activation of ICDs among patients from all 9 ICD clinics in the London National Health 

### 31 Service hospitals. “ Activation ” was defined as tachycardias for which th e defibrillator 

### 32 delivered treatment. Investigators modeled associations using unconstrained distributed 

### 33 lags from 0 to 5 days. The sample consisted of 705 patients with 5,462 activation days 

### 34 (O 3 information was for 543 patients and 4,092 activation days). Estimates for O 3 were 

### 35 consistently positive, although weak (OR: 1.09 [95% CI: 0.76, 1.55] per 30 ppb for 0

- 

### 36Draft

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- 147 September 2011 1 day lag; OR: 1.04 [95% CI: 0.60, 1.81] per 30 ppb for 0

- 5 day lag) ( Anderson et al., 

### 1 2010 )

. 

### 2 In contrast to arrhythmia studies conducted among ICD patients, Sarnat et al. ( 2006a ) 

### 3 recruited non

- smoking adults (age range: 54

- 90 years) to participate in a study of air 

### 4 pollution and arrhythmias conducted over two 12

- week periods during summer and fall 

### 5 of 2000 in a region characterized by industrial pollution (Steubenville, Ohio). Continuous 

### 6 ECG data acquired on a weekly basis over a 30

- minute sampling period were used to 

### 7 assess ectopy, defined as extra cardiac depolarizati ons within the atria (supraventricular 

### 8 ectopy, SVE) or the ventricles (ventricular ectopy, VE). Increases in the 5

- day moving 

### 9 average (days 1

- 5) of O 3 were associated with an increased odds of SVE (OR: 2.17 [95% 

### 10 CI: 0.93, 5.07] per 20 ppb increase in 24

- h avg O 3 concentrations). A weaker association 

### 11 was observed for VE (OR: 1.62 [95% CI: 0.54, 4.90] per 20 ppb increase in 24

- h avg O 3 

### 12 concentrations). The results of the effect of 5

- day O 3 on SVE were robust to the inclusion 

### 13 of SO 4 2

- in the model [OR: 1.62 (9 5% CI: 0.54, 4.90)]. The authors indicate that the 

### 14 strong associations observed at the 5

- day moving averages, as compared to shorter time 

### 15 periods, suggests a relatively long

- acting mechanistic pathways, such as inflammation, 

### 16 may have promoted the ectopic b eats in this population ( Sarnat et al., 2006a )

. 

### 17 Although many studies report positive associations, collectively, studies of arrhythmias 

### 18
r eport inconsistent results. This may be due to variation in study populations, length and 

### 19 season of averaging time, and outcome under study. Future studies are expected to 

### 20 provide additional evidence for the various outcomes and exposure periods. 

### 21

6.3.2.2 Heart Rat e/Heart Rate Variability
In the 2006 O 3 AQCD, two large population

- based studies of air pollution and HRV were 

### 22 summarized ( Park et a l., 2005b ; Liao et al., 2004a ) . In addition, the biological 

### 23 mechanisms and potential importance of HRV were discussed. Briefly, the study of acute 

### 24 adverse effects of air pollution on cardiac autonomic control is based on the hypothesis 

### 25 that increased air pollution levels may stimulate the autonomic nervous system and lead 

### 26 to an imbalance of cardiac autonomic control characterized by sympathetic activation 

### 27 unopposed by parasympathetic control ( U.S. EPA, 2006b ) . Examples of HRV indices 

### 28 include the standard deviation of normal

- to

- normal intervals (SDNN), the square root of 

### 29 the mean of the sum of the squares of differences between adjacent NN intervals (r



### 30 MSSD), high

- frequency power (HF), low

- frequency power (LF), and the LF/HF ratio. 

### 31 Liao et al. ( 2004a ) examined the association betwee n air pollution and cardiac autonomic 

### 32 control in the fourth cohort examination (1996

- 1998) of the U.S.

- based Atherosclerosis 

### 33 Risk in Communities Study. A decrease in log

- transformed HF was associated with an 

### 34Draft

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- 148 September 2011 increase in O 3 concentration among white study p articipants. Park et al. ( 2005b ) 

### 1 examined the effects of air pollution on indices of HRV in a population

- based study 

### 2 among men from the Normative Aging Study in Boston, Massachusetts. Several 

### 3 associations were observed with O 3 and HRV outcomes; a reduction in LF was associated 

### 4 with incre ased O 3 concentration, which was robust to inclusion of PM 2.5 . The associations 

### 5 with all HRV indices and O 3 were stronger among those with ischemic heart disease and 

### 6 hypertension. In addition to these population

- based studies included in the 2006 O 3 

### 7 AQCD w as a study by Schwartz et al. ( 2005 ) , who conducted a panel study to assess the 

### 8 relationship between exposure to summertime air pollution and HRV. A weak ass ociation 

### 9 of O 3 during the hour immediately preceding the health measures was observed with r



### 10 MSSD among a study population that consisted of mostly older female participants. In 

### 11 summary, these studies suggest that short

- term exposures to O 3 are predictors of 

### 12 decreased HRV and that the relationship may be stronger among certain subgroups. The 

### 13 generally consistent (although weak) associations between pollutants and reduced cardiac 

### 14 autonomic control were observed at relatively low pollution concentrations typi cally 

### 15 experienced by the U.S. general population on a daily basis ( U.S. EPA, 2006b ) . More 

### 16 recent studies of O 3 and HRV and are described below. The O 3 concentrations for these 

### 17 studies are presented in Table 6

- 30. 

### 18

Table 6 - 30 Characterizat ion of ozone concentrations (in ppb) from studies of heart rate variability
Reference Location Averaging Time Mean Concentration (Standard Deviation) Upper Range of Concentration Baja et al. ( 2010 ) Boston, MA 0 lag 10
- h lag 23 (16) 21 (15) Chan et al. ( 2005a ) Taipei, Taiwan 1
- h 21.9 (15.4) Max: 114.9 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 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) Ruidavets et al. ( 2005a ) Toulouse, France 8
- h 38.3 (14.8) 75th: 46.9 Max: 80.3 Wheeler et al. ( 2006 ) Atlanta, GA 4
- h 24
- h 18.5 29.4 75th: 22.5
Wu et al. ( 2010 ) Taipei, Taiwa n Working period 24.9 (14.0) Max: 59.2 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 *Median presented (information on mean not given).Draft

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- 149 September 2011 Several follow

- up examinations of HRV were conducted among the participants of the 

### 1 Normative Aging Study in Boston . A trajectory cluster analysis was used to assess 

### 2 whether pollution originating from different locations had varying relationships with 

### 3 HRV ( Park et al., 2007 ) . Subjects who were examined on days when air parcels 

### 4 originated in the west had the strongest associations with O 3 ; however, the O 3 

### 5 concentration in this cluster was low (24

- h avg, 17.0 ppb) compared to the other clusters 

### 6 (24

- h avg of 21.3

- 29.1 ppb). LF and SDNN decreased with increases in the 4

- h moving 

### 7 ave rage of O 3 from the west (LF decreased by 51.2% [95% CI: 1.6, 75.9%] and SDNN 

### 8 decreased by 28.2% [95% CI:

- 0.5, 48.7%] per 30 ppb increase in 4

- h avg O 3 

### 9 concentrations) ( Park et al., 2007 ) . The Boston air mass originatin g in the west traveled 

### 10 over Illinois, Indiana, and Ohio; states typically characterized by coal

- burning power 

### 11 plants. Due to the low O 3 concentrations observed in the west cluster, the authors 

### 12 hypothesize that O 3 on those days could be capturing the effect s of other, secondary 

### 13 and/or transported pollutants from the coal belt or that the relationship between ambient 

### 14 O 3 and personal exposure to O 3 is stronger during that period (supported by a 

### 15 comparatively low apparent temperature which could indicate a like lihood to keep 

### 16 windows open and reduced air conditioning use) ( Park et al., 2007 ) . An additional 

### 17 follow

- up evaluation using the Normative Aging Study examined the potential for effect 

### 18 modification by chronic lead exposur e on the relationship between air pollution and HRV 

### 19 ( Park et al., 2008 ) . Authors observed graded reductions in HF and LF of HRV in relation 

### 20 to O 3 (and sulfate) across increasing quartiles of tibia and patella lead (HF: %change 32.3 

### 21 [95% CI:

- 32.5, 159.3] for the first quartile of tibia Pb and

- 59.1 [95% CI:

- 77.3,

- 26.1] 

### 22 for the fourth quartile of tibia Pb per 30 ppb increase in 4

- h avg O 3 concentrations; LF: 

### 23 %change 8.0 [95% CI:

- 36.9, 84.9] for the first quartile of tibia Pb and

- 59.3 [95% CI:

- 

### 24 74.6,

- 34.8] for the fourth quar tile of tibia Pb per 30 ppb increase in 4

- h avg O 3 

### 25 concentrations). In addition, O 3 associations were similar when education and cumulative 

### 26 traffic

- adjusted bone lead levels were used in analyses. Authors indicate the possibility 

### 27 that O 3 (which has low ind oor concentrations) was acting as a proxy for sulfate 

### 28 (correlation coefficient for O 3 and sulfate = 0.57). Investigators of a more recent follow



### 29 up to the Normative Aging Study hypothesized that the relationships between short

- term 

### 30 air pollution exposures and ventricular repolarization, as measured by changes in the 

### 31 heart

- rate corrected QT interval (QTc), would be modified by participant characteristics 

### 32 (e.g., obesity, diabetes, smoking history) and genetic susceptibility to oxidative stress 

### 33 ( Baja et al., 2010 ) . No evidence of an association between O 3 (using a quadratic 

### 34 constrained distributed lag model and hourly exposure lag models over a 10

- h time 

### 35 windo w preceding the visit) and QTc was reported (change in mean QTc

- 0.74 [95% CI: 

### 36

- 3.73, 2.25]); therefore, potential effect modification of personal and genetic 

### 37 characteristics with O 3 was not assessed ( Baja et al., 2010 ) . Collectively, the results from 

### 38 studies that examined the Normative Aging Study cohort found an association between 

### 39Draft

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- 150 September 2011 increases in short

- term exposures to O 3 and decreases in HRV ( Park et al., 2008 ; Park et 

### 1 al., 2007 ; Park et al., 2005b ) although not consistently in all of the studies ( Baja et al., 

### 2 2010 ) . Further, observed relationships appear to be stronger among those with ischemic 

### 3 heart disease, hypertension, and elevated bone lead levels, as well as when air masses 

### 4 arrive from the west (the coal belt). However, it is not clear if O 3 i s acting as a proxy for 

### 5 other, secondary particle pollutants (such as sulfate) ( 2008 ; 2007 ; Park et al., 2005b ) . In 

### 6 addition, since the Normative Aging Study participants were older, predominately white 

### 7 men, results may not be generalizable to women, younger individuals, or those of 

### 8 different racial/ethnic groups ( Baja et al., 2010 )

. 

### 9 Additional studies of populations not limited to the Normative Aging Study have also 

### 10 examined associations between O 3 exposure and HRV. A panel study among 18 

### 11 individuals with COPD and 12 individuals with recent myocardial infarction (MI) was 

### 12 conducted in Atlanta, Georgia ( Wheeler et al., 2006 ) . HRV was assessed for each 

### 13 participant on 7 days in fall 1999 and/or spring 2000. The mean 4

- h O 3 concentration 

### 14 (time period immediately preceding the HRV measures) was 18.5 ppb; however, O 3 

### 15 concentrations differed substantially within study sites (8.0

– 33.8 ppb). Ozone 

### 16 concentrations were not associated with HRV (SDNN) among all subjects (percent 

### 17 cha nge of 2.36% [95% CI:

- 10.8%, 17.5%] per 30 ppb 4

- h O 3 increase) or when stratified 

### 18 by disease type (COPD, recent MI, and baseline FEV 1 ) ( Wheeler et al., 2006 )

. 

### 19 HRV and air pollution was assessed in a panel study among 46 predominately white male 

### 20 patients (study population: 80.4% male, 93.5% white) aged 43

- 75 years in Boston, 

### 21 Massachusetts, with coronary artery disease ( Zanobetti et al., 2010 ) . Up to four home 

### 22 visits were made to assess HRV over the year fo llowing the index event. Pollution lags 

### 23 used in analyses ranged between 30 minutes to a few hours and up to 5 days prior to the 

### 24 HRV assessments. Decreases in r

- MSSD were reported for all averaging times of O 3 

### 25 (percent change of

- 5.18% [95% CI:

- 7.89,

- 2.30 ] per 20 ppb of 5

- day moving average of 

### 26 O 3 concentration), but no evidence of an association between O 3 and HF was observed 

### 27 (quantitative results not provided). In two

- pollutant models with O 3 and either PM 2.5 or 

### 28 BC, O 3 associations remained robust. 

### 29 A few studies were conducted outside of the U.S. to assess the relationship between air 

### 30 pollution concentrations and heart rate and HRV ( Wu et al., 2010 ; Chuang et al., 2007b ; 

### 31 Chuang et al., 2007a ; Chan et al., 2005a ; Ruidavets et al., 2005a ) . No associations were 

### 32 reported between O 3 and HRV among CHD patients and patients with one or more major 

### 33 CHD risk factors residing in Taipei, Taiwan ( Chan et al., 2005a ) . Another study in 

### 34 Taipei, Taiwan examined mail carriers and reported O 3 levels measured using personal 

### 35 monitors. No associ ation was observed between O 3 and the measures of HRV (percent 

### 36 change for SDNN: 0.57 [95% CI:

- 21.27, 28.46], r

- MSSD:

- 7.10 [95% CI:

- 24.24, 13.92], 

### 37Draft

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- 151 September 2011 HF:

- 1.92 [95% CI:

- 23.68, 26.02], LF:

- 4.82 [95% CI:

- 25.34, 21.35] per 40 ppb O 3 ) 

### 1 ( Wu et al., 2010 ) . In addition, no consistent relationships were identified between O 3 and 

### 2 resting heart rate among middle

- aged (35

- 64 years) participants residing in Toulouse, 

### 3 France ( Ruidavets et al., 2005a ) . A negative trend was reported for the 3

- day cumulative 

### 4 (lag days 1

- 3) concentration of O 3 with heart rate (p for trend = 0.02); however, the 

### 5 individual odds r atios comparing quintiles of exposure showed no association (OR for O 3 

### 6 of 0.93 [95% CI: 0.86, 1.01] for the highest quintile of resting heart rate compared to the 

### 7 lowest). When stratified by current smoking status, non

- smokers had a decreased trend 

### 8 with in creased 3

- day cumulative O 3 concentrations but none of the quintiles for heart rate 

### 9 were statistically significant. A panel study was conducted in Taiwan to assess the 

### 10 relationship between air pollutants and inflammation, oxidative stress, blood coagulatio n, 

### 11 and autonomic dysfunction ( Chua ng et al., 2007b ; Chuang et al., 2007a ) . Participants 

### 12 were apparentl y healthy college students (aged 18

- 25 year) who were living in a 

### 13 university dormitory in metropolitan Taipei. Health endpoints were measured three times 

### 14 from April to June in 2004 or 2005. Ozone was assessed in statistical models using the 

### 15 average of the 24, 48, and 72 hours before the hour of each blood sampling. Decreases in 

### 16 HRV (measured as SDNN, r

- MSSD, LF, and HF) were associated with increases in O 3 

### 17 concentrations in single

- pollutant models (percent change for SDNN:

- 13.45 [95% CI:

- 

### 18 16.26,

- 10.60], r

- MSSD

- 13.76 [95% CI:

- 21.62,

- 5.44], LF

- 9.16 [95% CI:

- 13.29,

- 

### 19 4.95], HF

- 10.76 [95% CI:

- 18.88,

- 2.32] per 20 ppb 3

- day avg O 3 concentrations) and 

### 20 remained associated with 3

- day O 3 concentrations in two

- pollutant models with sulfate. 

### 21 Another study in Ta iwan recruited individuals with coronary heart disease or at risk for 

### 22 cardiovascular disease from outpatient clinics ( Chuang et al., 2007b ) . Mean O 3 

### 23 concentrations were 35.1 ppb (SD 27.5 ppb) during the study period (two weeks in 

### 24 February). No association was observed between O 3 concentrati on and HRV measures 

### 25 (SDNN, r

- MSSD, LF, HF) (numerical results not provided in publication). 

### 26 Overall, studies of O 3 concentration and HRV report inconsistent results. Multiple studies 

### 27 in Boston observed positive associations but the authors of many of these studies 

### 28 postulated that O 3 was possibly acting as a proxy for other pollutants. The majority of 

### 29 other studies, both in the U.S. and internationally, report null findings. The 

### 30 inconsistencies observed are further complicated by the different HRV measures a nd 

### 31 averaging times used by the studies. 

### 32

6.3.2.3 Stroke
The 2006 O 3 AQCD did not identify any studies that examined the association between 

### 33 short

- term O 3 exposure and stroke. However, recent studies have attempted to examine 

### 34 this relationship. Lisabeth et al. ( 2008 ) used a time

- series ap proach to assess the 

### 35Draft

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- 152 September 2011 relationship between daily counts of ischemic stroke and transient ischemic attack (TIA) 

### 1 with O 3 concentrations in a southeast Texas community among residents 45 years and 

### 2 older (2001

- 2005; median age of cases, 72 years). The median O 3 (hourly average per 24

- 

### 3 h time

- period) concentration was 25.6 ppb (IQR 18.1

- 33.8). The associations between 

### 4 same - day (RR: 1.03 [95% CI: 0.96, 1.10] per 20 ppb increase in 24

- h avg O 3 

### 5 concentrations ) and previous

- day (RR: 1.05 [95% CI: 0.99, 1.12] per 20 pp b increase in 

### 6 24

- h avg O 3 concentrations ) O 3 concentrations and stroke/TIA risk were positive. 

### 7 Associations were robust to adjustment for PM 2.5 . The effect of season on the relationship 

### 8 was not assessed. 

### 9 A case

- crossover design was used in a study conduct ed in Dijon, France between March 

### 10 1994 and December 2004, among those 40 years of age and older who presented with 

### 11 first

- ever stroke ( Henrotin et al., 2007 ) . The mean O 3 concentration, calculated over 8

- h 

### 12 daytime periods, was 14.95 ppb (IQR: 6

- 22 ppb). No association was observed between 

### 13 O 3 concentration at 0, 1, 2, or 3 days lag and hemorrhagic stroke. However, an 

### 14 association between ischemi c stroke occurrence and O 3 concentrations with a 1

- day lag 

### 15 was observed (OR: 1.54 [95% CI: 1.14, 2.09] per 30 ppb increase in 8

- h max O 3 

### 16 concentrations ). The effect of O 3 persisted in two

- pollutant models with PM 10 , SO 2 , NO 2 , 

### 17 or CO. This association was st ronger among men (OR: 2.12 [95% CI: 1.36, 3.30] per 30 

### 18 ppb increase in 8

- h max O 3 concentrations ) than among women (OR: 1.17 [95%CI: 0.77, 

### 19 1.78] per 30 ppb increase in 8

- h max O 3 concentrations ) in single pollutant models. When 

### 20 stroke was examined by subty pe among men, an association was observed for ischemic 

### 21 strokes of large arteries and for transient ischemic attacks but not for cardioembolic or 

### 22 lacunar ischemic strokes. The subtype analysis was not performed for women. 

### 23 Additionally, for men a linear expo sure - response was observed when O 3 was assessed 

### 24 based on quintiles (p for trend = 0.01) (Figure 6

- 21). A potential limitation of this study 

### 25 is that 67.4% of the participating men were smokers compared to 9.3% of the women. 

### 26 Another study, performed in Dijon, France, examined the association between O 3 

### 27 concentration and incidence of fatal and non

- fatal ischemic cerebrovascular events 

### 28 (ICVE) ( Henrotin et al., 2010 ) . Mean 8

- h O 3 concentration was 19.1 ppb (SD 12.2 ppb). 

### 29 A positive association was observed between recurrent ICVE and O 3 concentration with a 

### 30 3

- day lag (OR: 1.92 [95% CI 1.17, 3.12]), but not for other lags (0, 1, 2, 4) or cumulative 

### 31 days (0

- 1, 0

- 2, 1

- 2, 1

- 3). Although some ORs for incident ICVEs were elevated, none 

### 32 were statistically significant. Results for associations using the maximum daily 1

- h O 3 

### 33 concentrations were similar to the 8

- h results but s lightly attenuated. ORs were similar in 

### 34 two pollutant models (data not given). In stratified analyses, the association between 1

- 

### 35 day lagged O 3 concentration and incident and recurrent ICVE was greater among those 

### 36 with multiple other preexisting vascular co nditions. Increased associations with ICVE 

### 37 were also observed for individuals with diabetes or hypertension. 

### 38Draft

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- 153 September 2011 Source: Henrotin et al. ( 2007 )

. 

### Figure 6 - 21 Odds ratio (95% confidence interval) for stroke by quintiles of ozone

.


### 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 link ing air pollution 

### 2 and cardiovascular disease. A wide range of markers assessed as well as different types 

### 3 of study designs and locations chosen make comparisons across studies difficult. Table 6

- 

### 4 31 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

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- 154 September 2011 

### Table 6 - 31 Characterization of ozone concentrations (in ppb) from studies of biomarkers
Reference Location Averaging Time Mean Concentration (Standard Deviation) Upper Range of Concentration Baccarelli et al. ( 2007 ) Lombardia, Italy 1
- h 18.3* 75th: 35.1 Max: 202.3 Chen et al. ( 2007 ) Los Angeles and San Francisco, CA 8
- h/2 wk 30.8* Max: 47.9 8
- h/1 mo 28.3* Max: 43.1 Chuang et al. ( 2010 ) Taiwan 26.83 (9.7) Max: 62.1 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 Goldberg et al. ( 2008 ) Montreal, Quebec 24
- h NS Liao et al. ( 2005 ) 3 U.S. counties 8
- h 40 (20) Rudez et al. ( 2009 ) Rotterdam, the Netherlands 24
- h 22* 75th: 31.5 Max: 90 Steinvil et al. ( 2008 ) Tel
- Aviv, Israel 0.5
- h 29.2 (9.7) 75th: 36 Thompson et al. ( 2010 ) Toronto, Ontario 1
- h/1 yr 21.94 (15.78) Wellenius et al. ( 2007 ) Boston, MA 1
- h/24
- h 25.1 (12.9) *Median presented (information on mean not given). Hemostasis and coagulation markers Multiple studies used various markers to examine if associations were present between 

### 1 O 3 concentrations and hemostatis and coagulation. Some of the markers included in these 

### 2 studies were as follows: fibrinogen, von Willebrand factor (vWF), plasminogen activator 

### 3 fibrinogen inhibitor

- 1 (PAI

- 1), tissue

- type plasminogen activator (tPA), platelet 

### 4 aggregation, and thrombin 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 ) . Significant 

### 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 c oncentrations <40 ppb, 117% 

### 11 [0.86%] for O 3 concentrations 40

- 70 ppb, and 124% [1.97%] for O 3 concentrations of 70 

### 12 ppb). The association between O 3 and fibrinogen was more pronounced among those 

### 13 with a history of cardiovascular disease (CVD) and was statist ically significant among 

### 14 only this subgroup of the population. The curvilinear relationship between exposure and 

### 15 outcome suggested stronger relationships at higher concentrations of O 3 which could 

### 16 indicate threshold effects. The authors note that the most pronounced associations 

### 17 occurred when the pollutants were 2

- 3 standard deviations above the mean. The results 

### 18Draft

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- 155 September 2011 from this relatively large

- scale cross

- sectional study suggest weak associations with O 3 

### 1 and fibrinogen (among those with a history of CVD) and vW F. 

### 2 A retrospective repeated measures analysis was performed in Toronto, Canada among 

### 3 adults aged 18

- 40 years (n=45) between the years of 1999 and 2006 ( Thompson et al., 

### 4 2010 ) . Single pollutant models were used with moving averages up to 7 days. No 

### 5 evidence of an association was observed for O 3 and f ibrinogen. 

### 6 A repeated measures study was conducted in 40 healthy individuals living or working in 

### 7 the city center of Rotterdam, the Netherlands to assess the relationship between air 

### 8 pollution and markers of hemostatis and coagulation (platelet aggregatio n, thrombin 

### 9 generation, and fibrinogen) ( Rudez et al., 2009 ) . Ea ch participant provided between 11 

### 10 and 13 blood samples throughout a 1

- year period (498 samples on 197 days). Examined 

### 11 lags ranged from 6 hours to 3 days prior to blood sampling. No consistent evidence of an 

### 12 association was observed between O 3 and any of t he biomarkers (percent change of max 

### 13 platelet aggregation:

- 6.87 [95% CI:

- 21.46, 7.70] per 20 ppb 4

- day average O 3; percent 

### 14 change of endogenous thrombin potential: 0.95 [95% CI:

- 3.05, 4.95] per 20 ppb 4

- day 

### 15 avg O 3; percent change of fibrinogen:

- 0.57 [9 5% CI:

- 3.05, 2.00] per 20 ppb lag 1

- day 

### 16 O 3; ). Some associations with O 3 were in the opposite direction to that hypothesized which 

### 17 may be explained by the negative correlation between O 3 and the other pollutants 

### 18 (correlation coefficients ranged from

- 0.4 t o - 0.6). The statistically significant inverse 

### 19 effects observed with O 3 in single

- pollutant models were no longer apparent when PM 10 

### 20 was included in the models ( Rudez et al., 2009 )

. 

### 21 A panel study in Taiwan measured health endpoints using blood samples from healthy 

### 22 individuals (n=76) at three times from April to June in 2004 or 2005 ( Chuang et al., 

### 23 2007a ) . Increases in fibr inogen and PAI

- 1 were associated with increases in O 3 

### 24 concentrations in single

- pollutant models (percent change in fibrinogen: 11.76 [95% CI: 

### 25 4.03, 19.71] per 20 ppb 3

- day avg O 3 ; percent change in PAI

- 1: 6.08 [95% CI: 38.91, 

### 26 84.27] per 20 ppb 3

- day avg O 3 ). These associations were also observed at 1 and 2 day 

### 27 averaging times. Associations between PAI

- 1 and 3

- day O 3 concentrations remained 

### 28 robust in two

- pollutant models with sulfate. No association was seen between O 3 and 

### 29 tPA, a fibrinolytic factor (percent change 16.15 [95% CI:

- 4.62, 38.34] per 20 ppb 3

- day 

### 30 avg O 3 ). 

### 31 A study in Israel examined the association between pollutant concentrations and 

### 32 fibrinogen among 3659 apparently healthy individuals ( Steinvil et al., 2008 ) . In single 

### 33 pollutant models, O 3 was associated wi th an increase in fibrinogen at a 4

- day lag among 

### 34 men and a same

- day O 3 concentration among women but results for other lags (0 through 

### 35 7 days) were mixed (some positive, some negative; none statistically significant). 

### 36Draft

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- 156 September 2011 Inflammatory markers Air pollution a nd inflammatory markers (C

- reactive protein [CRP], white blood cell 

### 1 [WBC] count, albumin, and Interleukin

- 6 [IL

- 6]) were also examined in several studies. 

### 2 The ARIC study cohort, which included men and women aged 45

- 64 years old at the start 

### 3 of the study, w as utilized to assess the association between O 3 concentrations and makers 

### 4 of inflammation ( Liao et al., 2005 ) . No association was observed between O 3 

### 5 concentrations and albumin or WBC count. 

### 6 Thompson et al. ( 2010 ) assessed ambient air pollution exposures and IL

- 6. This 

### 7 retrospective repeated measures analysis was conducted among 45 adults (18

- 40 years of 

### 8 age) in Toronto, Canada between the years of 1999 and 2006. Single pollutant models 

### 9 were used to analyze the repeated

- measures data using moving averages up to 7 days. A 

### 10 positive association was observed between IL

- 6 and O 3 with the strongest effects 

### 11 observed for the 4

- day moving average of O 3 (quantitative results not provided). No 

### 12 association was seen for shorter averaging times (<1 day). When examined by season 

### 13 using 2

- day moving averages, the association between O 3 and IL

- 6 was positive during 

### 14 only the spring and summer. 

### 15 In Rotterdam, the Netherlands, a repeated measures study of healthy individuals living or 

### 16 working in the city center reported no association between O 3 concentration and CRP 

### 17 ( Rudez et al., 2009 ) . Each of the 40 participants provided between 11 and 13 blood 

### 18 s amples throughout a 1

- year period (498 samples on 197 days). No consistent evidence of 

### 19 an association was observed between O 3 and CRP (percent change:

- 0.48 [95% CI:

- 

### 20 14.05, 13.10] per 20 ppb lag 1

- day O 3 ). Additionally, no association was observed with 2 

### 21 or 3 day lags. 

### 22 The relationship between pollutant concentrations and one

- time measures of 

### 23 inflammatory biomarkers was assessed in sex

- stratified analyses among 3659 apparently 

### 24 healthy individuals in Tel Aviv, Israel ( Steinvil et al., 2008 ) . No evidence of an 

### 25 association was observed between O 3 and CRP or WBC for men and women. 

### 26 A panel study of healthy individuals (n=76) was conducted in Taiwan to assess the 

### 27 relationship between air pollutants and inflammation ( Chuang et al., 2007a ) . Health 

### 28 endpoints were measured three times from April to June in 2004 or 2005. Oz one effects 

### 29 were assessed in statistical models using the average of the 24 hours (1 day), 48 hours 

### 30 (2 days), and 72 hours (3 days) before the hour of each blood sampling. Increases in CRP 

### 31 were associated with increases in O 3 concentrations in single

- pollu tant models (percent 

### 32 change in CRP: 244.38 [95% CI: 4.54, 585.15] per 20 ppb 3

- day avg O 3 ). The association 

### 33 was also observed using a 2

- day averaging time, but no association was present with a 1

- 

### 34 day averaging time. 

### 35Draft

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- 157 September 2011 Oxidative stress markers A few studies h ave reported on the relationships between O 3 concentration and oxidative 

### 1 stress markers. The association between O 3 exposure and markers of lipid peroxidation 

### 2 and antioxidant capacity was examined among 120 nonsmoking healthy college students, 

### 3 aged 18

- 22 y ears, from the University of California, Berkeley (February

- June 2002) 

### 4 ( Chen et al., 2007 ) . By design, students were chosen that had experienced different 

### 5 geographic concentrations of O 3 over their lifetimes and during recent summer vacation 

### 6 in either greater Los An geles (LA) or the San Francisco Bay Area (SF). Long

- term 

### 7 (based on lifetime residential history) and shorter

- term (based on the moving averages of 

### 8 8

- h max concentrations 1

- 30 days prior to the day of blood collection) O 3 exposures were 

### 9 estimated (lifetime exposure results presented in the chronic exposure section). A marker 

### 10 of lipid peroxidation, 8

- isoprostane (8

- iso

- PGF), was assessed. This marker is formed 

### 11 continuously under normal physiological conditions but has been found at elevated 

### 12 concentrations in response to environmental exposures. A marker of overall antioxidant 

### 13 capacity, ferric reducing ability of plasma (FRAP), was also measured. Substantial 

### 14 overlap in the more recent O 3 exposure estimates (8

- h moving averages) was observed 

### 15 between the two geog raphic areas sampled. Levels of 8

- iso

- PGF were associated with 

### 16 2

- week (β = 0.035 [pg/mL]/8

- h ppb O 3 , p = 0.007) and 1

- month (β = 0.031 [pg/mL]/8

- 

### 17 h ppb O 3 , p = 0.006) estimated O 3 exposure levels. No evidence of association was 

### 18 observed between O 3 and FRAP. A chamber study performed among a subset of study 

### 19 participants supported the primary study results. The concentrations of 8

- iso

- PGF 

### 20 increased immediately after the 4

- h controlled O 3 exposure ended (p = 0.10). However, 

### 21 levels returned to near baseline by 1 8 hours without further exposure. The authors note 

### 22 that O 3 was highly correlated with PM 10

- 2.5 and NO 2 in this study population; however, 

### 23 inclusion of these pollutants in the O 3 models did not substantially change the magnitude 

### 24 of the associations with O 3 . 

### 25 Using blood samples collected between April and June of 2004 or 2005 in Taiwan, the 

### 26 association between O 3 concentrations and a marker of oxidative stress was studied 

### 27 among healthy individuals (n=76) ( Chuang et al., 2007a ) . Increases in 8

- hydroxy

- 2 ’

- 

### 28 deoxyguanosine (8

- OHdG) were associated with increases in O 3 concentrations in single



### 29 pollutant models (percent change in 8

- OHdG: 2.46 [95% CI: 1.01, 3.92] per 20 ppb 1

- day 

### 30 avg O 3 ). The association did not persist with 2

- or 3

- day averaging times. 

### 31

Markers of overall cardiovascular health Multiple studies used mark ers that assess overall cardiovascular well

- being. Wellenius et 

### 32 al. ( 2007 ) examined Β

- type natriuretic peptide (BNP), a marker of heart failure, in a 

### 33 repeated

- measures study conduct ed in Boston among 28 patients with congestive heart 

### 34Draft

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- 158 September 2011 failure and impaired systolic function. The authors found no evidence of an association 

### 1 between BNP and short

- term O 3 exposures at lags 0

- 3 days (quantitative results not 

### 2 provided). BNP was chosen becaus e it is directly associated with cardiac hemodynamics 

### 3 and symptom severity among those with heart failure and is, therefore, considered a 

### 4 marker of functional status. However, the authors conclude that the use of BNP may not 

### 5 be useful in studies of the hea lth effects of ambient air pollutants due to the large amount 

### 6 of within

- person variability in BNP levels observed in this population. 

### 7 The relationship between air pollution and oxygen saturation and pulse rate, markers of 

### 8 physiological well

- being, was exam ined in a 2

- month panel study among 31 congestive 

### 9 heart failure patients (aged 50

- 85 years) in Montreal, Canada from July 2002 to October 

### 10 2003 ( Goldberg et al., 2008 ) . All participants had limited physical functioning 

### 11 (New York Heart Association Classification ≥ II) and an ejection fraction (the fraction of 

### 12 blood pumped out of the heart per beat) less than or equal to 35% (normal is above 55%). 

### 13 Daily mean O 3 concentrat ions were calculated based on hourly measures at 10 monitoring 

### 14 stations. There was an inverse association between O 3 (lag

- 0) and oxygen saturation 

### 15 when adjustment was made for temporal trends. In the models incorporating personal 

### 16 covariates and weather fac tors, the association remained but was not statistically 

### 17 significant. The associations of O 3 with a lag of 1 day or a 3

- day mean were not 

### 18 statistically significant. No evidence of association was observed between O 3 exposure 

### 19 and pulse rate. 

### 20 Total homocyst eine (tHcy) is an independent risk factor for vascular disease and 

### 21 measurement of this marker after oral methionine load is used to identify individuals with 

### 22 mild impairment of homocysteine metabolism. The effects of air pollution on fasting and 

### 23 postmethio nine

- load tHcy levels were assessed among 1,213 apparently healthy 

### 24 individuals from Lombardia, Italy from January 1995 to September 2005 ( Baccarelli et 

### 25 al., 2007 ) . An increase in the 24

- h O 3 concentrations was associated with an increase in 

### 26 fasting tHcy (percent change 6.25 [95% CI: 0.84, 11.91] per 20 ppb O 3 ) but no 

### 27 association was observed with postmethi onine

- load tHcy (percent change 3.36 [95% CI:

- 

### 28 1.30, 8.39] per 20 ppb O 3 ). In addition, no evidence of association was observed between 

### 29 7

- day O 3 concentrations and tHcy (percent change for fasting tHcy 4.16 [95% CI:

- 1.76, 

### 30 10.42] and percent change for pos tmethionine

- load tHcy

- 0.65 [95% CI:

- 5.66, 4.71] per 

### 31 20 ppb O 3 ). No evidence of effect modification by smoking was observed. 

### 32
Blood lipids and glucose metabolism markers Chuang et al. ( 2010 ) conducted a population

- based cross

- sectional analysis of data 

### 33 collected on 7,778 participants during the Taiwanese Survey on Prevalence of 

### 34 Hyperglycemia, Hyperlipidemia, and Hypertension in 2001. Apolipoprotein B (ApoB), 

### 35Draft

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- 159 September 2011 the primary apolipoprotein among low

- density lipoproteins, was associated with 3

- day 

### 1 avg O 3 at the p < 0.10 level. The 5

- day mean O 3 concentration was associated with an 

### 2 increase in triglycerides at p < 0.10. In addition, the 1

- , 3

- , and 5

- day mean O 3 

### 3 concentrations were associated with increased HbA1c levels (a marker used to monitor 

### 4 the degree of control of glucose metabolism) at the p < 0.05 level. The 5

- day mean O 3 

### 5 was associated with increased fasting glucose levels (p < 0.10). No association was 

### 6 observed between O 3 concentration and ApoA1. Copollutant models were not assessed. 

### 7

6.3.2.5 Myocardial Infarction (MI)
The 2006 O 3 AQCD did not report consistent results indicating an association between 

### 8 short

- term O 3 exposure and MI. One study reported a positive association between 

### 9 current day O 3 concentration and acute MI, especially among the oldest age group (55

- to 

### 10 64

- year olds) ( Ruidavets et al., 2005b ) . No association was observed in a case

- crossover 

### 11 study of O 3 during the hours surrounding the event and MI ( Peters et al., 2001 ) . Since the 

### 12 2006 O 3 AQCD, a few new epidemiologic studies have examined the association between 

### 13 O 3 exposure and M I ( Henrotin et al ., 2010 ; Rich et al., 2010 ) , as well as one study 

### 14 p ublished on arterial stiffness ( Wu et al., 2010 ) and one study published on ST

- segment 

### 15 depression ( Delfino et al., 2011 )

. 

### 16 One of the studies conducted in the U.S. examined hospital admissions for first MI and 

### 17 reported no association with O 3 concentrations ( Rich et al., 2010 ) . More details on this 

### 18 study are reported in the section on hospital admissions. Another study, performed in 

### 19 Dijon, France, examined the association between O 3 concentration and incident and 

### 20 recurrent MI ( Henr otin et al., 2010 ) . The mean 8

- h O 3 concentration was 19.1 ppb (SD 

### 21 12.2 ppb). Odds ratios for the association between cumulative O 3 concentrations and 

### 22 recurrent MIs were elevated but none of the results were statistically significant (OR: 

### 23 1.71 [95% CI: 0.91, 3.20] per 20 ppb for cumulative 1

- 3 day O 3 exposure). No 

### 24 association was observed for incident MIs. In analyses stratified by vascular risk factors, 

### 25 positive associations were observed between 1

- day lagged O 3 concentrations and MIs 

### 26 (incident and recu rrent combined) among those who reported having 

### 27 hypercholesterolaemia (OR: 1.52 [95% CI: 1.08, 2.15] per 20 ppb O 3 ) and a slight inverse 

### 28 association was observed among those who reported not having hypercholesterolaemia 

### 29 (OR: 0.69 [95% CI: 0.50, 0.94] per 2 0 ppb O 3 ). In other stratified analyses combining 

### 30 different vascular factors, only those containing individuals with hypercholesterolaemia 

### 31 demonstrated a positive association; none were inverse associations. 

### 32 Wu et al. ( 2010 ) exami ned mail carriers aged 25

- 46 years and measured exposure to O 3 

### 33 through personal monitors [mean O 3 24.9 (SD 14.0) ppb]. Ozone exposure was positively 

### 34Draft

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- 160 September 2011 associated with arterial stiffness (percent change 11.24% [95% CI: 3.67, 19.62] per 40 

### 1 ppb O 3 ) and was robu st to adjustment for ultrafine PM. 

### 2 A study performed in the Los Angeles basin reported on the association between O 3 

### 3 exposure and ST

- segment depression, a measure representing cardiac ischemia ( Delfino 

### 4 et al., 2011 ) . Study participants were nonsmokers, at least 65 years old, had a history of 

### 5 coronary artery disease, and were living in a retirement community. Study periods 

### 6 included five consecutive d ays in both July to mid

- October and mid

- October to February. 

### 7 Mean 24

- h O 3 concentrations were 27.1 ppb (SD 11.5 ppb). No association was observed 

### 8 between O 3 concentrations and ST

- segment depression of at least 1.0 mm during any of 

### 9 the exposure periods (i.e ., 1

- h, 8

- h, 1

- day , 2

- day avg, 3

- day avg, 4

- day avg). 

### 10

6.3.2.6 Blood Pressure
In the 2006 O 3 AQCD, no epidemiologic studies examined O 3 - related effects on blood 

### 11 pressure (BP). Recent studies have been conducted to evaluate this relationship and 

### 12 overall the findings are inconsistent. The O 3 concentrations for these studies are listed in 

### 13 Table 6

- 32. 

### 14

Table 6 - 32 Characterization of ozone concentrations (in ppb) from studies of blood pressure
Reference Location Averaging Time Mean Concentration (Standard Deviat ion) Upper Range of Concentration Choi et al. ( 2007 ) Incheon, Sou th 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 Delfino et al. ( 2010b ) Los Angeles, California 24
- h 27.1 (11.5) Max: 60.7 Zanobetti et al. ( 2004 ) Boston, Massachusetts 1
- h 20 5
- days 24 Chuang et al. ( 2010 ) Taiwan 26.83 (9.7) Max: 62.1
Zanobetti et al. ( 2004 ) examined the relationship between air pollutants and BP from 

### 15 May 1999 to January 2001 for 631 repeat visits among 62 Boston residents with CV D. In 

### 16 single

- pollutant models, higher resting diastolic blood pressure (DBP) was associated 

### 17 with the 5

- day (0

- 4 days) averages of O 3 (RR: 1.03 [95% CI: 1.00, 1.05] per 20 ppb 

### 18 increase in 24

- h O 3 concentrations). However, this effect was no longer apparent when 

### 19 PM 2.5 was included in the model (data were not presented) ( Zanobetti et al., 2004 )

. 

### 20 Delfino et al. ( 2010b ) examined 64 subjects 65 years and older with coronary artery 

### 21Draft

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- 161 September 2011 disease, no tobacco smoke exposure, and living in retirement communities in the 

### 1 Los Angeles air basin with hourly (up to 14

- h/day) ambulatory BP monitoring for 5 days 

### 2 during a warm period (July

- mid

- October) and 5 days during a cool period (mid

- October



### 3 February). Investigators assessed lags of 1, 4, and 8 hours, 1 day, and up to 9 days before 

### 4 each BP measure; no evidence of association was observed for O 3 exposures (change in 

### 5 BP associated with a 20 ppb change in 24

- h O 3 was 0.67 [95% CI:

- 1.16, 2.51 for systolic 

### 6 BP [SBP] and

- 0.25 [95% CI:

- 1.25, 0.75] for DBP) ( Delfino et al., 2010b )

. Choi et al. 

### 7 ( 2007 ) conducted a cross

- sectional study to investigat e the relationship between air 

### 8 pollutants and BP among 10,459 participants of the Inha University Hospital health 

### 9 examination from 2001 to 2003. These individuals had no medical history of 

### 10 cardiovascular disease or hypertension. O 3 exposure was associated with an increase in 

### 11 SBP for 1

- day lag in the warm season and similar effect estimates were observed during 

### 12 the cold season but were not statistically significant (quantitative results not provided). 

### 13 Associations between O 3 and DBP were present in the cold season but not the warm 

### 14 season (quantitative results not provided). The interaction term between O 3 and season 

### 15 was statistically significant. Chuang et al. ( 2010 ) conducted a similar type of study 

### 16 among 7,578 participants of the Taiwanese Survey on Prevalence of Hyperglycemia, 

### 17 Hyperlipidemia, and Hypertension in 2001. Investigators examined 1

- , 3

- , and 5

- day avg 

### 18 O 3 concentrations. An increase in DBP was associated with the 3

- day mean O 3 

### 19 concentration (change in BP for a 20 ppb increase in O 3 was 0.6 1 [95% CI: 0.07, 1.14]) 

### 20 ( Chuang et al., 2010 ) . Associations were not observed for other days or with SBP. 

### 21

6.3.2.7 Hospital Admissions and Emergency Department Visits Upon evaluating the collective evidence for O 3 - related cardiovascular hospital admissions 

### 22 ( HAs) and emergency department (ED) visits, the 2006 O 3 AQCD concluded that “ a few 

### 23 studies observed positive O 3 associations, largely in the warm season. Overall, however, 

### 24 the currently available evidence is inconclusive regarding any association between 

### 25 am bient O 3 exposure on cardiovascular hospitalizations ” ( U.S. EPA, 2006b ) . Table 6

- 33 

### 26 below provides information on the O 3 concentrations reported in each of the recent HA 

### 27 and ED visit studies evaluated. 

### 28 Multiple recent studies of O 3 exposure and cardiovascular HAs and ED visits have been 

### 29 conducted in the U.S. and Canada. Peel et al. ( 2007 ) used a case

- crossover framework 

### 30 (using a time

- stratified approac h matching on day of the week in the calendar month of 

### 31 the event) to assess the relationship between air pollutants and cardiovascular disease ED 

### 32 visits among those with and without secondary comorbid conditions (hypertension, 

### 33 diabetes, chronic obstructive pulmonary disease [COPD], congestive heart failure [CHF], 

### 34Draft

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- 162 September 2011 

### Table 6 - 33 Characterization of ozone concentrations (in ppb) from studies of HAs and ED visits Study Location Averaging Time Mean Concentration (Standard Deviation) Upper Range of Concentration Azevedo et al. ( 2011 ) Portug al 1
- h NR Ballester et al. ( 2006 ) Multicity, Spain 8
- h warm season 24.2
- 44.3
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 Cakmak et al. ( 2006a ) Multicity, Canada 1
- h max 17.4 Chan et al. ( 2006 ) Taipei, Taiwan 1
- h max 50.9 (26.4) Max: 150.3 Halonen et al. ( 2009 ) Helsinki, Finland 8
- h max warm season 35.7* 75th: 42.1 Max: 79.6 Hosseinpoor et al. ( 2005 ) Tehran, Iran 8
- h max 4.9 (4.8) 75th: 7.2 Max: 99.0 Lanki et al. ( 2006 ) Multicity, Europe 8
- h max warm season 31.7
- 57.2*
Larrieu et al. ( 2007 ) Multicity France 8
- h max warm season 34.2
- 53.1
Lee et al. ( 2003b ) Seoul, Korea 1
- h max 36.0 (18.6) 75th: 44 .9 Lee et al. ( 2007 ) Kaohsiung, Taiwan 24
- h 26.5 75th: 35.5 Max: 83.0 Middleton et al. ( 2008 ) Nicosia, Cyprus 8
- h max 28.7
- 54.9 Peel et al. ( 2007 ) Atlanta, GA 8
- h max warm season 55.6 (23.8)

Rich et al. ( 2010 ) New Jersey 24
- h NR Stieb et al. ( 2009 ) Multicity, Canada 24
- h 18.4 Symons et al. ( 2006 ) Baltimore, MD 8
- h warm season 31.0 (20.0) Max: 120.0

Tolbert et al. ( 2007 ) Atlanta, GA 8
- h max warm season 53.0 75th: 67.0 Max: 147.5 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

Von Klot et al. ( 2005 ) Multicity, Europe 8 h max warm season 16.4
- 28.0
Wellenius et al. ( 2005 ) Allegheny Cou nty, PA 24
- h 24.3 (12.2) 75th: 32.0 Yang ( 2008 ) Taipei, Taiwan 24
- h 21.0 75th: 26.3 Max: 62.8 Zanobetti and Schwartz ( 2006 ) Boston, MA 24
- h 22.4* 75th: 31.0 *Median presented (information on mean not given). NR: Not reportedDraft

– Do Not Cite or Quote 6
- 163 September 2011 and dysrhythmia). Data on over 4 million ED visits from 31 hospitals were collected 

### 1 from January 1993 to August 2000. Ozone was monitored from March to October. This 

### 2 study was a re

- analysis of a time series study conducted to assess the main effects of air 

### 3 pollutants on cardiovascular ED visits in Atlanta ( Tolbert et al., 2007 ; Metzger et al., 

### 4 2004 ) . In the initial study, no evidence of associations was observed between O 3 and all 

### 5 CVD visits or visits for CVD subgroups, such as dysrhythmia, CHF, ischemic heart 

### 6 disease (IHD), and peripheral vascular and cerebrovascular disease. The relative risk for 

### 7 all CVD visits was 1.01 (95% CI: 0.99, 1 .02) for a 20 ppb increase in the 3

- day moving 

### 8 avg (lags 0

- 2 days) of 8

- h O 3 ( Metzger et al., 2004 ) . Similar to the initial investigation 

### 9 using a time

- series analysis, no evidence of an association was observ ed for the O 3 3

- day 

### 10 moving average and CVD visits among the entire population using the case

- crossover 

### 11 design ( Peel et al., 2007 ) . However, the relationship between O 3 and perip heral and 

### 12 cerebrovascular disease visits was stronger among patients with comorbid COPD (OR: 

### 13 1.19 [95% CI: 1.03

- 1.36] per 20 ppb, lag 0

- 2 days) as compared to patients without 

### 14 COPD (OR: 1.01 [95% CI: 0.97

- 1.04] per 20 ppb, lag 0

- 2 days). The same research 

### 15 group expanded upon the number of Atlanta hospitals providing ED visit data (41 

### 16 hospitals) as well as the length of the study period (1993

- 2004) ( Tolbert et al., 2007 )

. 

### 17 Again, models assessing the health effects of O 3 utilized data collected from March 

### 18 through October. Similar to the results presented by Metzger et al. ( 2004 ) and Peel et al. 

### 19 ( 2007 ) among the entire study population, no evidence of associations was observed for 

### 20 O 3 and CVD visits ( Tolbert et al., 2007 )

. 

### 21 A study of HAs for MI was performed using a statewide registry from New Jersey 

### 22 between January 2004 and December 2006 ( Rich et al., 2010 ) . Using a case

- crossover 

### 23 design, the association between the previous 24 hr O 3 concentration and transmural 

### 24 infarction (n=1,003) was examined. No association was observed (OR: 0.94 [95% CI: 

### 25 0.79, 1.13] per 20 ppb) and this did not change with the inclusion of PM 2.5 in the model. 

### 26 Cakmak et al, ( 2006b ) investigated the relationship between gaseous air pollutants and 

### 27 cardiac hospitalizations in 10 large Canadian cities using a time

- series approach. A total 

### 28 o f 316,234 hospital discharge records for primary diagnosis of congestive heart failure, 

### 29 ischemic heart disease, or dysrhythmia were obtained from April 1993 through March 

### 30 2000. Correlations between pollutants varied substantially across cities, which could 

### 31 partially explain discrepancies in effect estimates observed across the cities. In addition, 

### 32 pollutant lags differed across cities; the average lag for O 3 was 2.9 days. The pooled 

### 33 effect estimate for a 20 ppb increase in the daily 1

- h max O 3 concentration and the 

### 34 percent change in hospitalizations among all 10 cities was 2.3 (95% CI: 0.11, 4.50) in an 

### 35 all

- year analysis. The authors reported no evidence of effect modification by gender, 

### 36 neighborhood

- level education, or neighborhood

- level income. A similar m ulticity time



### 37 series study was conducted using nearly 400,000 ED visits to 14 hospitals in seven 

### 38Draft

– Do Not Cite or Quote 6
- 164 September 2011 Canadian cities from 1992 to 2003 ( Stieb et al., 2009 ) . Primary analyses considered daily 

### 1 O 3 single day lags of 0

- 2 days; in addition, sub

- daily lags of 3

- h avg concentrations up to 

### 2 12 hours before presentation to the ED were considered. Seasonal variation was assessed 

### 3 by stratifying analyses by warm and cold seasons. No evide nce of effect of O 3 on CVD 

### 4 ED visits was observed. One negative, statistically significant association was reported 

### 5 between a 1

- day lag of O 3 and visits for angina/myocardial infarction. Ozone was 

### 6 negatively correlated with many of the other pollutants, pa rticularly during the cold 

### 7 season. 

### 8 The effect of air pollution on daily ED visits for ischemic stroke (n=10,881 visits) in 

### 9 Edmonton, Canada was assessed from April 1992 through March 2002 ( Szyszkowicz, 

### 10 2008 ) . A 26.4% (95% CI: 3.16

- 54.5) increase in stroke ED visits was associated with a 

### 11 20 ppb increase in O 3 at lag 1 among men aged 20

- 64 years in the warm season. No 

### 12 associations were present among women or among men age 65 and older. In addition, no 

### 13 associations were observed for the cold season or for other lags (lag 0 or lag 2). A similar 

### 14 investigation over the same time period in Edmonton, Canada, assessed the relationship 

### 15 between air pollutants and ED visits for stroke (ischemic stroke, hemorrhagic stroke, and 

### 16 transient ischemic attack) among those 65 years of age and older using a case

- crossover 

### 17 framework ( Villeneuve et al., 2006a ) . Two

- pollutant models were assessed. No evidence 

### 18 of association was reported for O 3 and stroke ho spitalization ( Villeneuve et al., 2006a )

. 

### 19 Additional studies reported no evidence of an association between O 3 concentrations and 

### 20 ED visits, hospitalizations, or symptoms leading to hospitalization ( Symons et al., 2006 ; 

### 21 Zanobetti and Schwartz, 2006 ; Wellenius et al., 2005 ) . Symons et al. ( 2006 ) used a case



### 22 crossover framework to assess the relationship between air pollutants and the onset of 

### 23 symptoms (dyspnea) severe enough to lea d to hospitalization (through the ED) for 

### 24 congestive heart failure. The study was conducted from April to December of 2002 in 

### 25 Baltimore, Maryland. Exposures were assigned using 3 index times: 8

- h and 24

- h periods 

### 26 prior to symptom onset and date of hospital admission. No evidence of association was 

### 27 reported for O 3 concentrations. Although seasonal variation was not assessed, the time 

### 28 frame for the study did not involve an entire year (April to December). Wellenius et al. 

### 29 ( 2005 ) investigated the association between air pollutants and congestive heart failure 

### 30 hospitalization among Medicare beneficiaries in Pittsburgh, Pennsylvania from 1987 to 

### 31 1999 utilizing a case

- crossover framework. A total of 55,019 admissions from the 

### 32 emergency room with a primary discharge diagnosis of CHF were collected. No evidence 

### 33 of an association was reported for O 3 and CHF hospitalization ( Wellenius et al., 2005 )

. 

### 34 Finally, Zanobetti and Schwartz ( 2006 ) assessed the relationship between air pollutants 

### 35 and hospital admissions through the ED for myocardial infarction and pneumonia among 

### 36 patients aged 65 and older residing in the gr eater Boston area (1995

- 1999) using a case



### 37 crossover framework with control days in the same month matched on temperature. 

### 38Draft

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- 165 September 2011 Pollution exposures were assigned for the same day and for the mean of the exposure the 

### 1 day of and the day before the admission. Ozon e was not associated with MI admissions in 

### 2 all

- year and seasonal analyses. 

### 3 Several recent studies have examined the relationship between air pollution and CVD 

### 4 hospital admissions and/or emergency department visits in Asia. Of note, some areas of 

### 5 Asia have a more tropical climate than the U.S. and do not experience similar seasonal 

### 6 changes. In Taiwan, fairly consistent positive associations have been reported for O 3 and 

### 7 congestive heart failure hospital admissions (for single

- and copollutant models) in Tai pei 

### 8 on warm days ( Yang, 2008 ) and in Kaohsiung ( Lee et al., 2007 ) ; cerebrovascular disease 

### 9 ED visits (for lag 0 single

- and two

- pollutant models but not other lags or 3

- pollutant 

### 10 models) in Taipei ( Chan et al., 2006 ) ; and arrhythmia ED visits in Taipei among those 

### 11 without comorbid conditions ( Chiu et al., 2009 ; Lee et al., 2008a ) and in Taipei on warm 

### 12 days among those with and without comorbid conditions ( Lee et al., 2008a ; Jansson et al., 

### 13 2001 ) . However, one study in Taiwan did not shown an association . Bell et al. ( 2008 ) 

### 14 reported no evidence of an O 3 association wit h hospital admissions for ischemic heart 

### 15 disease or cerebrovascular disease. Three studies based in Asia but outside Taiwan were 

### 16 performed. First, a Hong Kong

- based investigation ( Wong et al., 2009 ) reported no 

### 17 consistent evidence of a modifying effect of influenza on the relationship between O 3 and 

### 18 CVD admissions. Second, among elderly populations in Thailand, O 3 was associated with 

### 19 CVD visits, but this association was not detected among younger age groups (15

- 64) 

### 20 ( Buadong et al., 2009 ) . Third, a study performed in Seoul, Korea reported a positive 

### 21 association between O 3 levels and HAs for ischemic heart disease; the association was 

### 22 slightly greater among those over 64 years of age ( Lee et al., 2003b )

. 

### 23 Positive effects of O 3 on CVD hospital admissions and/or ED visits have been reported in 

### 24 other areas of the world as well ( Azevedo et al., 2011 ; Linares and Diaz, 2010 ; Middleton 

### 25 et al., 2008 ; Turner et al., 2007 ; Yallop et al., 2007 ; Ballester et al., 2006 ; De Pablo et al., 

### 26 2006 ; Von Klot et al., 2005 ) , although not consistently as some studies reported no 

### 27 association ( Oudin et al., 2010 ; Halonen et al., 2009 ; Larrieu et al., 2007 ; Barnett et al., 

### 28 2006 ; Hinwood et al., 2006 ; Lanki et al., 2006 ; Hosseinpoor et al., 2005 ; Simpson et al., 

### 29 2005 )

. 

### 30 A couple of studies (U.S. and Australia) have examined cardiac arrests where emergency 

### 31 services attempted treatmen t/resuscitation. No evidence of an association between O 3 and 

### 32 out

- of

- hospital cardiac arrest was observed ( Dennekamp et al., 2010 ; Silverman et al., 

### 33 2010 )

. 

### 34 An increasing number of air pollution studies have investigated the relationship between 

### 35 O 3 concentrations and CVD hospital admissions and/or ED visits. As summarized in the 

### 36 2006 O 3 AQCD, some, especially those reporting results stratified by season (or 

### 37Draft

– Do Not Cite or Quote 6
- 166 September 2011 temperature) or comorbid conditions have reported positive associations. However, even 

### 1 studie s performing these stratified analyses are not consistent and the overall evidence 

### 2 remains inconclusive regarding the effects of O 3 on CVD HAs and ED visits. These HA 

### 3 and ED visit studies are summarized in Figures 6

- 22 through 6

- 26, which depict the 

### 4 associ ations for studies in which numerical associations were presented for an overall 

### 5 study population. Tables 6

- 34 through 6

- 38 provide the numerical results displayed in the 

### 6 figures. 

### 7

Note: Increase in O 3 standardized to 20 ppb for 24
- h avg period, 30 ppb f or 8
- h avg period, and 40 ppb for 1
- h avg period. 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 Fung et al. ( 2005 ) , Wong et al. ( 1999b ) , and Prescott et al. ( 19 98 ) , which included only individuals aged 65+. 

### Figure 6 - 22 Odds ratio (95% CI) per increment ppb increase in ozone for over all cardiovascular ED visits or HAs. Reference Buadong 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) 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 Nicosia, Cyprus Windsor, Canada Valencia, Spain Brisbane, Australia Los Angeles, CA London, England Hong Kong Hong Kong Edinburgh, Scotland London, England Helsinki, Finland 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**

0.7 0.8 0.9 1 1.1 1.2 1.3 1.4 1.5Draft

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- 167 September 2011 

### Table 6 - 34 Odds ratio (95% CI) per increment ppb increase in ozone for overall cardiovascula r ED visits or HAs in studies presented in Figure 6 - 22 Study Location Outcome Averaging Time Standardized Estimate (95% CI) Atkinson et al. ( 2006a ) London, England Cardiovascular disease 8
- h 1.03 (1.00, 1.05) Ballester et al. ( 2006 ) Multicity, Spain Cardiovascular disease 8
- h warm season 1.04 (1.02 , 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, 1.0 2) Buadong et al. ( 2009 ) Bangkok, Thailand Cardiovascul ar disease 1
- h 1.01 (1.00, 1.02) Cakmak et al. ( 2006a ) Multicity, Canada 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. ( 2006a ) Windsor, Canada Cardiovascular disease 1
- h 1.02 (0.92, 1.13) Halonen et al. ( 2009 ) Helsinki, Finland Cardiovascular disease 8
- h max warm season 1.05 (0.96, 1.14) Larrie u et al. ( 2007 ) Multicity France Cardiac disease 8
- h max warm season 1.01 (0.98, 1.04) Linn et al. ( 2006a ) Los Angeles, California Cardiovascu lar disease 24
- h 0.99 (0.98, 1.00) Middleton et al. ( 2008 ) Nicosia, Cyprus Cardiovascular disease 8
- h max 1.09 (1.00, 1.18) Morgan et al. ( 2008 ) Sydney, Austral ia Cardiac disease 1
- h max 1.02 (0.99, 1.05) Peel et al. ( 2007 ) Atlanta, GA Cardiovascular disease 8
- h warm season 1.00 (0.98, 1.02) Cerebrovascular disease 8
- h warm season 1.02 (0.98, 1.05) Petroeschevsky et al. ( 2001 ) Brisbane, Australia Cardiovascular disease 8
- h 0.96 (0.92, 1.01) Poloniecki et al. ( 2006a ) 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 Cardiovascular disease 24
- h 0.89 (0.78, 1.00) Von Klot et al. ( 2005 ) Multicity, Europe 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. ( 2005 ) Kaohsiung, Taiwan Cardiovascular disease 24
- h warm season 1.33 (1.26 , 1.40) 24
- h cold season 1.05 (0.96, 1.15) Note: Increase in O 3 standardized to 20 ppb for 24
- h averaging period, 30 ppb for 8
- h averaging period, and 40 ppb for 1
- h averaging period. Ozone concentrations in ppb. Age groups of study populations were not specified or were adults with the exception of Fung et al. ( 2006a ) , Wong et al. ( 1999a ) , and Prescott et al. ( 1998 ) , which included only individuals aged 65+.

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 ( Lar rieu et al., 2007 ; Von Klot et al., 2005 ) , ≥ 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

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- 168 September 2011 Note: Increase in O 3 standardized to 20 ppb for 24
- h averaging period, 30 ppb for 8
- h averaging period, and 40 ppb for 1
- h averaging period. Ozone concentrations in ppb. Seasons depicted by colors: black: all year; red: warm season; light blue: col d season. Outcomes were all congestive heart failure, with the excepti on 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+. 

### Figure 6 - 23 Odds Ratio (95% CI) per increment ppb increase in ozone for c ongestive heart failure ED visits or HAs. 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

0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2Draft

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- 169 September 2011 

### Table 6 - 35 Odds Ratio (95% CI) per increment ppb increase in ozone for congestive heart failure ED visits or HAs for studies in Figure 6 - 23 Study Location Outcome Averaging Time Standardized 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 0.96 (0.93, 1.00) Poloniecki et al. ( 1997 ) London, England congestive heart failure 8
- h 0.99 (0.95, 1.03) Stieb et al. ( 2009 ) Multicity, Canada 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, 1.4 1) 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 s eason 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) Wong et al. ( 1999b ) Hong Kong congestive heart failure 24
- h 1.25 (1.11, 1.41)

Note: Increase in O 3 standardized to 20 ppb for 24
- h averaging period, 30 ppb for 8
- h averaging period, and 40 ppb for 1
- h averaging period. 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 symptom s 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+.

Warm season defined as: March
- October ( Peel et al., 2007 ) , April
- Novem ber ( Symo ns et al., 2006 ) , May
- October ( Wong et al., 1999a ) ≥ 20°C ( Yang, 20 08 ) , 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

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- 170 September 2011 Note: Increase in O 3 standardized to 20 ppb for 24
- h averaging period, 30 ppb for 8
- h averaging period, and 40 ppb for 1
- h averaging period. Ozone concentrations in ppb. Seasons depicted by colors: black: all year; red: warm season; light blue: col d season. Age groups of stud y populations were not specified or were adults with the exception of Wong et al. ( 1999a ) and Atkinson et al. ( 2006a ) , which included only individuals aged 65+. 

### Figure 6 - 24 Odds Ratio (95% confidence interval) per increment ppb increase in ozone for ischemic heart disease, coronary heart disease, myocardial infarction, and angina pectoris ED visits or HAs. 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 1.5Draft

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- 171 September 2011 

### Table 6 - 36 Odds Ratio (95% CI) per increment ppb increase in ozone for ischemic heart disease, coronary heart disease, myocardial infarction, and angina pectoris ED visits or HAs for studies presented in Figure 6 - 24 Study Location Outcome Averaging Time Standardized 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 ) Multicity, Europe Myocardial infarction 8
- h max warm season 0.96 (0.92, 1.01) Larrieu et al. ( 2007 ) Multicity France Ischemic heart disea se 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 (0.97, 1.03) Poloniecki et al. ( 1997 ) London, England Myocardial infarction 8
- h 0.98 (0.94, 1.02) Angina 8
- h 0.98 (0.94, 1.03) Rich et al. ( Rich et al., 2010 ) New Jersey Myocardial infarction 24
- h 0.94 (0.79, 1.13) Stieb et al. ( 2009 ) Multicity, Canada Myocardial infarction 2
- h 1.00 (0.96, 1.04) Von Klot et al. ( 200 5 ) Multicity, Europe 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. ( 2009 ) 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. ( 2008 ) 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)

Note: Increase in O 3 standardized to 20 ppb for 24
- h averaging period, 30 ppb for 8
- h averaging period, and 40 ppb for 1
- h averaging period. Ozone concentrations in ppb. Age groups of study populations were not specified or were adults with the exception of Wong et al. ( 1999a ) and Atkinson et al. ( 20 06a ) , which included only individuals aged 65+.

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 ; Von Klot et al., 2005 ) . Cold season defined as: November
- April ( Buadong et al., 2009 )Draft

– Do Not Cite or Quote 6
- 172 September 2011 Note: Increase in O 3 standardized to 20 ppb for 24
- h averaging period, 30 ppb for 8
- h averaging period, and 40 ppb for 1
- h averaging period. Ozone concentrations in ppb. Seasons depicted by colors: black: all year; red: warm season; light blue: col d 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 ) , which included only individuals aged 50+. 

### Figure 6 - 25 Odds Ratio (95% confidence interval) per increment ppb increase in ozone for stroke ED visits or HAs. 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 1.5Draft

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- 173 September 2011 

### T

able 6 - 3 7 Odds Ratio (95% CI) per increment ppb increase in ozone for stroke ED visits or HAs for studies presented in Figure 6 - 25 Study Location Outcome Averaging Time Standardized 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 ) Multicity, France 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) Note: Increase in O 3 standardized to 20 ppb for 24
- h averaging period, 30 ppb for 8
- h averaging period, and 40 ppb for 1
- h averaging period. 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+.

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 )

.

Note: Increase in O 3 standardized to 20 ppb for 24
- h averaging period, 30 ppb for 8
- h averaging period, and 40 ppb for 1
- h averaging period. Ozone concentrations in ppb. Seasons depicted by colors: black: all year; red: warm season; light blue: col d season. Age groups of study populations were not specified or were adults with the exception of Wong et al. ( 1999a ) , which included only individuals aged 65+. 

### Figure 6 - 26 Odds Ratio (95% confidence interval) per increment ppb* increase in ozone for arrhythmia and dysrhythmia ED visits or HAs. 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

0.7 0.8 0.9 1 1.1 1.2 1.3 1.4Draft

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- 174 September 2011 

### Table 6 - 38 Odd s Ratio (95% CI) per increment ppb* increase in ozone for arrhythmia and dysrhythmia ED visits or HAs for studies presented in Figure 6 - 26 Study Location Outcome Averaging Time Standardized Estimate (95% CI) Buadong et al. ( 2009 ) Bangkok, Thailand Arrhythmia 1
- h 0.99 (0.95, 1.04) Halonen et al. ( 200 9 ) 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 (0.98, 1.04) Poloniecki et al. ( 2009 ) London, England Arrhythmia 8
- h 1.02 (0.96, 1.07) Stieb et al. ( 2009 ) Multicity, Canada Dysrhythmia 24
- h 1.02 (0.95, 1.09) Wong et al. ( 2009 ) 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) Note: Increase in O 3 standardized to 20 ppb for 24
- h averaging period, 30 ppb for 8
- h averaging period, and 40 ppb for 1
- h averaging period. 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 individuals aged 65+. 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 between 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 

### 5 provided evidence, primarily from sin gle

- city studies, of consistent positive associations 

### 6 between short

- term O 3 exposure and cardiovascular mortality. Recent multicity studies 

### 7 conducted in the U.S., Canada, and Europe further confirm the association between short



### 8 term O 3 exposure and cardiov ascular mortality. 

### 9 As discussed in Section 6.2.7.2, the APHENA study ( Katsouyanni et al., 2009 ) also 

### 10 examined associations between short

- term O 3 exposure and mortality and found 

### 11 consistent positive associations for cardi ovascular mortality in all

- year analyses with 

### 12 associations persisting in analyses restricted to the summer season. Additional multicity 

### 13 studies from the U.S. ( Zanobetti and Schwartz, 2008b ) , Europe ( Samoli et al., 2009 ) , 

### 14 Italy ( Stafoggia et al., 2010 ) , and Asia ( Wong et al., 2010 ) that conducted summer season 

### 15 and/or all

- year analyses provide additional support for an association between short

- term 

### 16 O 3 exposure and cardiovascular mortality (Figure 6

- 37). 

### 17 Of the studies evaluated, only the APHENA study ( Katsouyanni et al., 2009 ) and the 

### 18 Italia n multicity study ( Stafoggia et al., 2010 ) conducted an analysis of the potential for 

### 19 copollutant confounding of the O 3 - cardiovascular mortality relationship. In the Eu ropean 

### 20Draft

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- 175 September 2011 dataset, when focusing on the natural spline model with 8 df/year (Section 6.2.7.2) and 

### 1 lag 1 results in order to compare results across study locations (Section 6.6.2.1), 

### 2 cardiovascular mortality risk estimates were robust to the inclusion of PM 10 in 

### 3 copollutant models in all

- year analyses with more variability in the Canadian and U.S. 

### 4 datasets (i.e., cardiovascular O 3 mortality risk estimates were reduced or increased in 

### 5 copollutant models). In summer season analyses, cardiovascular O 3 mortality ri sk 

### 6 estimates were robust in the European dataset and attenuated but remained positive in the 

### 7 U.S. dataset. Similarly, in the Italian multicity study ( Stafoggia et al., 201 0 ) , which was 

### 8 limited to the summer season, cardiovascular mortality risk estimates were robust to the 

### 9 inclusion of PM 10 in copollutant models. Based on the APHENA and Italian multicity 

### 10 results, O 3 cardiovascular mortality risk estimates appear to be ro bust to inclusion of 

### 11 PM 10 in copollutant models. However, in the U.S. and Canadian datasets there was 

### 12 evidence that O 3 cardiovascular mortality risk estimates are moderately to substantially 

### 13 sensitive (e.g., increased or attenuated) to PM 10 . The mostly eve ry - 6th

- day sampling 

### 14 schedule for PM 10 in the Canadian and U.S. datasets greatly reduced their sample size 

### 15 and limits the interpretation of these results. 

### 16

6.3.2.9 Summary of Epidemiologic Studies Overall, the available body of evidence examining the relationship b etween short

- term 

### 17 exposures to O 3 and cardiovascular morbidity is inconsistent. Differences in exposure 

### 18 metrics and windows of exposure, a wide variety of biomarkers considered, and a lack of 

### 19 consistency among definitions used for specific cardiovascular d isease endpoints (e.g. 

### 20 arrhythmias, HRV) make comparisons across studies difficult. In addition, several 

### 21 investigators reporting associations between O 3 and cardiovascular morbidity postulate 

### 22 that O 3 may be acting as a proxy for sulfate; differences reported across multicity studies 

### 23 and across studies conducted in specific cities/regions point to the importance of 

### 24 considering multipollutant relationships that vary across geographic regions. Additional ly 

### 25 mortality studies indicate a consistent positive association between O 3 and cardiovascular 

### 26 mortality. 

### 27

6.3.3 Toxicology

6.3.3.1 Summary of Findings from Previous Ozone AQCDs In the previous O 3 AQCDs ( U.S. EPA, 2006b , 1996a ) experimental ani mal studies have 

### 28 reported relatively few cardiovascular system alterations after exposure to O 3 and other 

### 29Draft

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- 176 September 2011 photochemical oxidants. The limited amount of research directed at examining O 3 - 

### 1 induced cardiovascular effects has primarily found alterations in hear t rate (HR) and BP 

### 2 after O 3 exposure. A group of studies ( Arito et al., 1992 ; Arito et al., 1990 ; Uchiyama and 

### 3 Yokoyama, 1989 ; Yokoyama et al., 1989 ; Uchiyama et al., 1986 ) report O 3 (0.1

- 1.0 ppm) 

### 4 exposure in rats decreased core temperature (T CO ), HR, and mean arterial pressure 

### 5 (MAP). However, these cardiovascular responses to O 3 co uld be attenuated by increased 

### 6 ambient temperatures, exhibited adaptation, and were the result of the rodent 

### 7 hypothermic response ( Watkinson et al., 2003 ; Watkinson et al., 1993 ) . This hypothermic 

### 8 response could be an attempt to minimize the irritant effects of O 3 inhalation, serving as a 

### 9 physiological and behavioral defense mechanism ( Iwasaki et al., 1998 ; Arito et al., 1997 )

. 

### 10 As humans do not appear to exhibit decreased HR, MAP, and T CO with routine 

### 11 environmental exposures to O 3 , caution must be used in extrapolating the results of these 

### 12 animal studies to humans (Section 6.3.1). 

### 13 Other studies have shown that O 3 can increase BP in animal models. Rats exposed to 

### 14 0.6 ppm O 3 for 33 days had increased systolic pressure and HR ( Revis et al., 1981 )

. 

### 15 Increased BP triggers the release of atrial natriuretic factor (ANF), which has been found 

### 16 in increased levels in the heart, lungs, and circulation of O 3 exposed (0.5 ppm) ra ts 

### 17 ( Vesely et al., 1994a , b , c ) . High concentration O 3 exposure (1.0 ppm) has also been 

### 18 found to lead to heart and lung edema ( Friedman et al., 1983 ) , which could be the re sult 

### 19 of increased ANF levels. Thus, O 3 may increase blood pressure and HR, leading to 

### 20 increased ANF and tissue edema. 

### 21 The toxicological studies that have examined the effect of O 3 on the cardiovascular 

### 22 system demonstrate O 3 - induced responses, but it remai ns unclear if the mechanism is 

### 23 through a reflex response or due to O 3 reaction products, which have been sparsely 

### 24 studied. Oxysterols derived from cholesterol ozonation, such as β

- epoxide and 5β,6β



### 25 epoxycholesterol (and its metabolite cholestan

- 6

- oxo - 3,5

- d iol), have been implicated in 

### 26 inflammation associated with cardiovascular disease ( Pulfer et al., 2005 ; Pulfer and 

### 27 Murphy, 2004 ) . Two other cholesterol ozonolysis products, atheronal

- A and

- B (e.g. 

### 28 cholesterol secoaldehyde), have been found in human atherosclerotic plaques and shown 

### 29 in vitro to induce foam cell formation and induce cardiomyocyte apoptosis and necrosis 

### 30 ( Sathishkumar et al., 2005 ; Wentworth et al., 2003 ) ; however, these products have not 

### 31 been found in the lung compartment or systemically after O 3 exposure. The ability to 

### 32 form these cholesterol ozonation products in the circulation in the absence of O 3 exposure 

### 33 complicates their implication in O 3 induced cardiovascular disease. 

### 34 Although it has been proposed that O 3 reaction products released after the interaction of 

### 35 O 3 with ELF constituents (See Section 5.1.2 on O 3 interaction with ELF) are responsible 

### 36 for systemic effects, it is not known whether they gain access to the vascular space. 

### 37Draft

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- 177 September 2011 Alternatively, extrapulmonary release of diffusible mediators, such as cytokines or 

### 1 endothelins, may initiate or propagate inflammatory responses in the vascular or systemic 

### 2 compartments ( Cole and Freeman, 2009 ) (Section 5.1.9.1). Ozone reacts within the lung 

### 3 to amplify ROS production, induce pulmonary inflammation, and activate inflammatory 

### 4 cells, resulting in a cascading proinflammatory state and ex trapulmonary release of 

### 5 diffusible mediators that could lead to cardiovascular injury. 

### 6

6.3.3.2 Recent Cardiovascular Toxicology Studies According to recent short

- term O 3 exposure animal toxicology studies, O 3 plays a role in 

### 7 inducing vascular oxidative stress and proinflammatory mediators, altering HR and HRV, 

### 8 and regulating the pulmonary endothelin system (study details are provided in Table 6

- 

### 9 39). A number of these effects were variable between strains examined, suggesting a 

### 10 genetic component to development of O 3 induced cardiovascular effects. Further, new 

### 11 studies provide evidence that extended O 3 exposure enhances susceptibility to ischemia



### 12 reperfusion (I/R) injury and atherosclerotic lesion development. Still, few studies have 

### 13 investigated the role of O 3 react ion products in these processes, but more evidence is 

### 14 provided for elevated inflammatory and reduction

- oxidation (redox) cascades known to 

### 15 initiate these cardiovascular pathologies. 

### 16 A recent study in young mice and rhesus monkeys examined the effects of s hort

- term O 3 

### 17 exposure on a number of cardiovascular endpoints ( Chuang et al., 2009 ) . Mice exposed to 

### 18 O 3 for 5 days had increased HR as well as mean and diastolic blood pressure. Increased 

### 19 blood pressure could be explained by the inhibition in endothelial

- dependent 

### 20 (acetylcholine) vasorelaxation from decreased bioavailability of aortic nitric oxide (·NO). 

### 21 Ozone caused a decrease in aortic NO X (nitrite and nitrate levels) and a decrease in total, 

### 22 b ut not phosphorylated, endothelial nitric oxide synthase (eNOS). Ozone also increased 

### 23 vascular oxidative stress in the form of increased aortic and lung lipid peroxidation (F2

- 

### 24 isoprostane), increased aortic protein nitration (3

- nitrotyrosine), decreased ao rtic 

### 25 superoxide dismutase (SOD2) protein and activity, and decreased aortic aconitase 

### 26 activity, indicating specific inactivation by O 2 - and ONOO - . Mitochondrial DNA 

### 27 (mtDNA) damage was also used as a measure of oxidative and nitrative stress in mice 

### 28 and inf ant rhesus monkeys exposed to O 3 . Chuang et al. ( 2009 ) observed that MtDNA 

### 29 damage accumulated in the lung and aorta of mice after 1 and 5 days of O 3 exposure and 

### 30 in the proximal and distal aort a of O 3 treated nonhuman primates. Additionally, 

### 31 genetically hyperlipidemic mice exposed to O 3 for 8 weeks had increased aortic 

### 32 atherosclerotic lesion area (Section 7.3.1), which may be associated with the short

- term 

### 33 exposure changes discussed. Overall, th is study suggests that O 3 initiates an oxidative 

### 34 environment by increasing O 2 - production, which leads to mtDNA damage and ·NO 

### 35Draft

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- 178 September 2011 consumption, known to perturb endothelial function ( Chuang et al., 2009 ) . Endothelial 

### 1 dysfunction is characteristic of early and advanced atherosclerosis and coincides with 

### 2 impaired vasodilation and blood pressure regulation. 

### 3 Vascular occlusion resulting from atherosclerosis can block blood flow causing ischemia. 

### 4 The r estoration of blood flow in the vessel or reperfusion can cause injury to the tissue 

### 5 from subsequent inflammation and oxidative damage. Perepu et al. ( 2010 ) observed that 

### 6 O 3 exposure enhanced the sensitivity to myocardial I/R injury in rats while increasing 

### 7 oxidative stress levels and pro

- inflammatory mediators and decreasing pro duction of anti



### 8 inflammatory proteins. Ozone was also found to decrease the left ventricular developed 

### 9 pressure, rate of change of pressure development, and rate of change of pressure decay 

### 10 while increasing left ventricular end diastolic pressure in isolat ed perfused hearts. In this 

### 11 ex vivo heart model, O 3 induced oxidative stress by decreasing SOD enzyme activity and 

### 12 increasing malondialdehyde levels. Ozone also elicited a proinflammatory state which 

### 13 was evident by an increase in TNF

- α and a decrease in th e anti

- inflammatory cytokine 

### 14 IL

- 10. Perepu et al. ( 2010 ) concluded that O 3 exposure may result in a greater I/R injury. 

### 15
Heart Rate and Heart Rate Variability Strain differences in HR and HRV have been observed in response to a 2

- h O 3 

### 16 pretreatment followed by exposure to carbon black (CB) in mice (C3H/HeJ [HeJ], 

### 17 C57BL/6J [B6], and C3H/HeOuJ [OuJ]) ( Hamade and Tankersley, 2009 ; Hamade et al., 

### 18 2008 ) . These mice strains were c hosen from prior studies on lung inflammatory and 

### 19 hyperpermeability responses to be susceptible (B6 and OuJ) and resistant (HeJ) to O 3 - 

### 20 induced health effects ( Kleeberger et al., 2000 ) . HR decreased during O 3 pre - exposure for 

### 21 all strains, but recovered during the CB exposure ( Hamade et al., 2008 ) . This is contrary 

### 22 to the tachycardia that was reported in 6

- week

- old B6 mice treated on 1 or 5 days with 

### 23 O 3 , as described above ( Chuang et al., 2009 ) . Percent change in HRV parameters, SDNN 

### 24 (indicating total HRV) and rMSSD (indicating beat

- to

- beat HRV), were increased in both 

### 25 C3H mice strains, but no t B6 mice, during O 3 pre - exposure and recovered during CB 

### 26 exposure when compared to the filtered air group. The two C3H strains differ by a 

### 27 mutation in the Toll

- like receptor 4 (TLR4) gene, but these effects did not seem to be 

### 28 related to this mutation sinc e similar responses were observed. Hamade et al. ( 2008 ) 

### 29 speculate that the B6 and C3H strains differ in mechanisms of HR response after O 3 

### 30 exposure between withdrawal of sympathetic tone and increase of parasympathetic tone; 

### 31 however, no direct evidence for this conclusion was reported. The strain difference s 

### 32 observed in HR and HRV suggest that genetic variability affects cardiac responses after 

### 33 acute air pollutant exposures. 

### 34Draft

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- 179 September 2011 Hamade and Tankersley ( 2009 ) continued this investigation of gene

- environment 

### 1 interactions on cardiopulmonary adaptation of O 3 and CB induced changes in HR and 

### 2 HRV using the previously described ( Hamade et al., 2008 ) daily exposure scheme for 3 

### 3 consecutive days. B y comparing day

- 1 interim values it is possible to observe that O 3 

### 4 exposure increased SDNN and rMSSD, but decreased HR in all strains. Measures of HR 

### 5 and HRV in B6 and HeJ mice recovered to levels consistent with filtered air treated mice 

### 6 by day 3; however , these responses in OuJ mice remained suppressed. B6 mice had no 

### 7 change in respiratory rate (RR) after O 3 treatment, whereas HeJ mice on days 1 and 2 had 

### 8 increased RR and OuJ mice on days 2 and 3 exhibited increased RR. V T did not change 

### 9 with treatment am ong the strains. Overall, B6 mice were mildly responsive with rapid 

### 10 adaptation, whereas C3 mice were highly responsive with adaptation only in HeJ mice 

### 11 with regards to changes in cardiac and respiratory responses. HR and HRV parameters 

### 12 were not equally cor related with V T and RR between the three mice strains, which 

### 13 suggest that strains vary in the integration of the cardiac and respiratory systems. These 

### 14 complex interactions could help explain variability in interindividual susceptibility to 

### 15 adverse health effects of air pollution. 

### 16 Hamade et al. ( 2010 ) expanded their investig ation to explore the variation of these strain 

### 17 dependent cardiopulmonary responses with age. As was observed previously, all 

### 18 experimental mouse strains (B6, HeJ, and OuJ) exhibited decreased HR and increased 

### 19 HRV after O 3 exposure. Younger O 3 - exposed mice h ad a significantly lower HR 

### 20 compared to older exposed mice, indicating an attenuation of the bradycardic effect of O 3 

### 21 with age. Younger mice also had a greater increase in rMSSD in HeJ and OuJ strains and 

### 22 SDNN in HeJ mice. Conversely, B6 mice had a slightl y greater increase in SDNN in 

### 23 aged mice compared to the young mice. No change was observed in the magnitude of the 

### 24 O 3 induced increase of SDNN in OuJ mice or rMSSD in B6 mice. The B6 and HeJ mice 

### 25 genetically vary in respect to the nuclear factor erythroid 2

- related factor 2 (Nrf

- 2). The 

### 26 authors propose that the genetic differences between the mice strains could be altering the 

### 27 formation of ROS, which tends to increase with age, thus modulating the changes in 

### 28 cardiopulmonary physiology after O 3 exposure. 

### 29 St rain and age differences in HR and heart function were further investigated in B6 and 

### 30 129S1/SvlmJ (129) mice in response to a sequential O 3 and filtered air or CB exposure 

### 31 ( Tankersley et al., 2010 ) . Young 129 mice showed a decrease in HR after O 3 or O 3 and 

### 32 CB exposure. This bradycardia was not observed in B6 or older animals in this study, 

### 33 suggesting a possible alteration or adaptation of the autonomic nervous system activity 

### 34 with age. However, these authors did previously report bradycardia in similarl y aged 

### 35 young B6 mice ( Hamade et al., 2010 ; Hamade and Tankersley, 2009 ; Hamade et al., 

### 36 2008 ) . Ozone exposure in 129 mice also resulted in an increase in left ventricular 

### 37 chamber dimensions at end diastole (LVEDD) in young and old mice and a decrease in 

### 38Draft

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- 180 September 2011 left ventricular posterior wall thickness at end systole (PWTES) in older mice. The 

### 1 increase in LVEDD caused a decrease in fractional shortening, which can be used as a 

### 2 rough indicator of left ventricular function. Regression analysi s revealed a significant 

### 3 interaction between age and strain on HR and PWTES, which implies that aging affects 

### 4 the HR and function in response to O 3 differently between mouse strains. 

### 5

Effects on Cardiovascular - Related Proteins Increased BP, changes in HRV, and increased atherosclerosis may be related to increases 

### 6 in the vasoconstrictor peptide, endothelin

- 1 (amino acids 1

- 21, ET

- 1 [1

- 21] ). Regulation of 

### 7 the pulmonary endothelin system can be affected in rats by inhalation of PM (0, 5, 

### 8 50 mg/m 3 , EHC

- 93) and O 3 ( Thomson et al., 2006 ; Thomson et al., 2005 ) . Exposure to 

### 9 either O 3 (0.8 ppm) or PM increased plasma ET

- 1 [1

- 21] , ET

- 3 [1

- 21] , and the ET

- 1 precursor 

### 10 peptide, bigET

- 1. Increases in circulating ET

- 1 [1

- 21] could be a result of a transient 

### 11 increase in the gene expression of lung preproET

- 1 and endothelin converting enzyme

- 1 

### 12 (ECE

- 1) immediately following inhalation of O 3 or PM. These latter gene expression 

### 13 changes (e.g. preproET

- 1 and ECE

- 1) were additi ve with co

- exposure to O 3 and PM. 

### 14 Conversely, preproET

- 3 decreased immediately after O 3 exposure, suggesting the 

### 15 increase in ET

- 3 [1

- 21] was not through de novo production. A recent study also found 

### 16 increased ET

- 1 gene expression in the aorta of O 3 exposed rats ( Kodavanti et al., 2011 )

. 

### 17 These rats also exhibited an increase in ET B R after O 3 exposure; however, they did not 

### 18 demons trate increased biomarkers for vascular inflammation, thrombosis, or oxidation. 

### 19 O 3 can oxidize protein functional groups and disturb the affected protein. For example, 

### 20 the soluble plasma protein fibrinogen is oxidized by O 3 (0.01

- 0.03 ppm) in vitro , creat ing 

### 21 fibrinogen and fibrin aggregates, characteristically similar to defective fibrinogen 

### 22 ( Rosenfeld et al., 2009 ; Rozenfeld et al., 2008 ) . In these studies, oxidized fibrinogen 

### 23 retained the ability to form fibrin gels that are involved in coagulation, h owever the 

### 24 aggregation time increased and the gels were rougher than normal with thicker fibers. 

### 25 Oxidized fibrinogen also developed the ability to self assemble creating fibrinogen 

### 26 aggregates that may play a role in thrombosis. Since O 3 does not readily tr anslocate past 

### 27 the ELF and pulmonary epithelium and fibrinogen is primarily a plasma protein, it is 

### 28 uncertain if O 3 would have the opportunity to react with plasma fibrinogen. However, 

### 29 fibrinogen can be released from the basolateral face of pulmonary epith elial cells during 

### 30 inflammation, where the deposition of fibrinogen could lead to lung injury ( Lawrence 

### 31 and Simpson

- Haidari s, 2004 )

. 

### 32Draft

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- 181 September 2011 Studies on Ozone Reaction Products Although recent toxicological studies have demonstrated O 3 - induced effects on the 

### 1 cardiovascular system, as concluded in previous O 3 AQCDs, it remains unclear if the 

### 2 mechanism is through a reflex response or the result of effects from O 3 reaction products 

### 3 ( U.S. EPA, 2006b , 1996a ) . A new study that examined O 3 reaction byproducts has shown 

### 4 that cholesterol sec oaldehyde (e.g., atheronal A) induces apoptosis in vitro in mouse 

### 5 macrophages ( Gao et al., 2009b ) and cardiomyocytes ( Sathishkumar et al., 2009 )

. 

### 6 Additionally, atheronal

- A and

- B has been found to induce in vitro macrophage and 

### 7 endothelial cell proinflammatory events involved in the initiation of atherosclerosis 

### 8 ( Takeuchi et al., 2006 ) . These O 3 reaction produ cts when complexed with low density 

### 9 lipoprotein upregulate scavenger receptor class A and induce dose

- dependent 

### 10 macrophage chemotaxis. Atheronal

- A increases expression of the adhesion molecule, E



### 11 selectin, in endothelial cells, while atheronal

- B induces mo nocyte differentiation. These 

### 12 events contribute to both monocyte recruitment and foam cell formation in 

### 13 atherosclerotic vessels. It is unknown whether these O 3 reaction products gain access to 

### 14 the vascular space from the lungs. Alternative explanations inc lude the extrapulmonary 

### 15 release of diffusible mediators that may initiate or propagate inflammatory responses in 

### 16 the vascular or systemic compartments. 

### 17Draft

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- 182 September 2011 

### Table 6 - 39 Characterization of study details for Section 6.3.3.2 a Study 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 environment 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

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 st ress 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 exposure, 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 ) M ice; 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 Significant interaction between age and strain on HR and PWTES, which implies that aging affects the HR and function in response to O 3 differ ently between mouse strains. Thomson et al. ( 2005 ) Rat; Fischer
- 344; M; 200
- 250 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 plasma 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. Summary of Toxicological Studies Overall, animal studies suggest that O 3 exposure may disrupt both the ·NO and 

### 1 endothelin systems, which c an result in an increase in HR, HRV, and ANF, as is 

### 2 observed after O 3 exposure. Conversely, studies in rodents also exhibit O 3 induced 

### 3 bradycardia, but it is uncertain if this decrease in HR is also observed in humans. 

### 4 Additionally, O 3 may increase oxidati ve stress and vascular inflammation promoting the 

### 5 progression of atherosclerosis and leading to increased susceptibility to I/R injury. As O 3 

### 6 reacts quickly with the ELF and does not translocate to the heart and large vessels, 

### 7 studies suggest that the card iovascular effects exhibited could be caused by reaction 

### 8Draft

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- 183 September 2011 byproducts of O 3 exposure. However, direct evidence of translocation of O 3 reaction 

### 1 products to the cardiovascular system has not been demonstrated in vivo . Alternatively, 

### 2 extrapulmonary release of d iffusible mediators, such as cytokines or endothelins, may 

### 3 initiate or propagate inflammatory responses in the vascular or systemic compartments 

### 4 leading to the reported cardiovascular pathologies. Further discussion of the modes of 

### 5 action that may lead to cardiovascular effects can be found in Section 5.3.8. 

### 6

6.3.4 Summary and Causal Determination In past O 3 AQCDs the effects of O 3 to the cardiovascular system did not receive much 

### 7 attention due to the paucity of information available. However, in recent years, 

### 8 investigation of O 3 - induced cardiovascular events has advanced. In general, compared 

### 9 with the epidemiologic evidence, the to xicological evidence is more supportive of O 3 - 

### 10 induced cardiovascular effects. Epidemiologic evidence does not consistently 

### 11 demonstrate a positive relationship between short

- term O 3 exposure and cardiovascular



### 12 related morbidity. However, most epidemiologic studies have not extensively 

### 13 investigated the cardiovascular effects of O 3 exposure in susceptible populations, which 

### 14 may further support the toxicological findings. Although the epidemiologic evidence of 

### 15 cardiovascular morbidity is limited, single

- city st udies reviewed in the 2006 O 3 AQCD, 

### 16 recent multicity studies, and the multicontinent APHENA study provide evidence of 

### 17 consistently positive associations between short

- term O 3 exposure and cardiovascular 

### 18 mortality. However, in contrast with respiratory effe cts, there is weak coherence between 

### 19 associations for cardiovascular morbidity and mortality. Further, there is no apparent 

### 20 biological mechanism to explain the association observed for short

- term O 3 exposure 

### 21 with cardiovascular mortality. 

### 22 Animal toxicologi cal studies provide evidence for O 3 - induced cardiovascular effects, 

### 23 specifically enhanced I/R injury, disrupted NO

- induced vascular reactivity, decreased 

### 24 cardiac function, and increased HRV. The observed increase in HRV is supported by a 

### 25 recent controlled human exposure study that also finds increased high frequency HRV, 

### 26 but not altered blood pressure, following O 3 exposure. Toxicological studies investigating 

### 27 the role of O 3 in heart rate regulation are mixed with both bradycardic and tachycardic 

### 28 responses observed. These changes in cardiac function provide evidence for O 3 - induced 

### 29 alterations in the autonomic nervous system leading to cardiovascular complications. 

### 30 Epidemiologic studies showing positive association between O 3 and arrhythmias confirm 

### 31 the devel opment of autonomic dysfunction following O 3 exposure. It is still uncertain 

### 32 how O 3 inhalation may cause systemic toxicity; however the cardiovascular effects of O 3 

### 33 found in animals correspond to the development and maintenance of an extrapulmonary 

### 34 oxidati ve, proinflammatory environment. 

### 35Draft

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- 184 September 2011 In conclusion, animal toxicological studies provide stronger evidence for O 3 exposure 

### 1 leading to cardiovascular morbidity than do epidemiologic studies, among which there is 

### 2 a lack of coherence among endpoints. Based on the relatively strong body of 

### 3 toxicological evidence, and the consistent evidence of an association between O 3 a nd 

### 4 cardiovascular mortality, but weak coherence and biological plausibility for O 3 - induced 

### 5 cardiovascular morbidity, the generally limited body of evidence is suggestive of a 

### 6 causal relationship between relevant short - term exposures to O 3 and 

### 7 cardiovascula r effects. 

### 8


## 6.4 Central Nervous System Effects
The 2006 O 3 AQCD included toxicological evidence that acute exposures to O 3 are 

### 9 associated with alterations in neurotransmitters, motor activity, short and long term 

### 10 memory, and sleep patterns. Additionally, hist ological signs of neurodegeneration have 

### 11 been observed. Reports of headache, dizziness, and irritation of the nose with O 3 

### 12 exposure are common complaints in humans, and some behavioral changes in animals 

### 13 may be related to these symptoms rather than indicat ive of neurotoxicity. Peterson and 

### 14 Andrews ( 1963 ) and Tepper et al. ( 1983 ) showed that mice would alter their behavior to 

### 15 avoid O 3 exposure. Murphy et al. ( 1964 ) and Tepper et al. ( 1982 ) showed that running



### 16 wheel behavior was suppressed, and Tepper et al. ( 1985 ) subsequently demonstrated the 

### 17 effects of a 6

- h exposure to O 3 on the suppression of running

- wheel behavior in rats and 

### 18 mice, with the lowest effective concentration being about 0.12 ppm O 3 in the rat and 

### 19 about 0.2 ppm in the mouse. The suppression of active behavior by 6 h of exposure to 

### 20 0.12 ppm O 3 has recently been confirmed by Martrette et al. ( 2011 ) in juvenile female 

### 21 rats, and the suppression of three different active behavior parameters was found to 

### 22 become more pronounced after 15 days of exposure. A table of studies examining the 

### 23 effects of O 3 on behavior can be found on p 6

- 128 of the 1996 O 3 AQCD. Generally 

### 24 speaking, transient changes in behavior in rodent models appear to be dependent on a 

### 25 complex interaction of factors such as (1) the type of behavior being measured, with 

### 26 some behaviors incr eased and others suppressed; (2) the factors motivating that behavior 

### 27 (differences in reinforcement); and (3) the sensitivity of the particular behavior (e.g., 

### 28 active behaviors are more affected than more sedentary behaviors). Many behavioral 

### 29 changes are l ikely to result from avoidance of irritation, but more recent studies indicate 

### 30 that O 3 also directly affects the CNS. 

### 31 Research in the area of O 3 - induced neurotoxicity has notably increased over the past few 

### 32 years, with the majority of the evidence coming f rom toxicological studies that examined 

### 33 the association between O 3 exposure, neuropathology, and neurobehavioral effects, and 

### 34 more limited evidence from epidemiologic studies. In an epidemiologic study conducted 

### 35Draft

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- 185 September 2011 by Chen and Schwartz ( 2009 ) , data from the NHANES III cohort was utilized to study 

### 1 the relationship between long

- term O 3 exposure (mean annual O 3 concentration of 

### 2 26.5 ppb) and neurobehavioral effects among adults aged 20

- 59 years. The authors 

### 3 observed an association between annual exposure to O 3 and tests measuring coding 

### 4 ability and attention/short

- term memory. Each 10

- ppb increase in annual O 3 levels 

### 5 corresponded to an aging

- related cognitive performance decline of 3.5 years for codin g 

### 6 ability and 5.3 years for attention/short

- term memory. These associations persisted in 

### 7 both crude and adjusted models. There was no association between annual O 3 

### 8 concentrations and reaction time tests. The authors conclude that overall there is a 

### 9 positiv e association between O 3 exposure and reduced performance on neurobehavioral 

### 10 tests. Although Chen and Schwartz ( 2009 ) is a long

- term exposure study, it is included in 

### 11 this section because it i s the first epidemiologic study to demonstrate that exposure to 

### 12 ambient O 3 is associated with decrements in neurocognitive tests related to memory and 

### 13 attention in humans. This epidemiologic evidence of an effect on the CNS due to 

### 14 exposure to ambient conce ntrations of O 3 is coherent with animal studies demonstrating 

### 15 that exposure to O 3 can produce a variety of CNS effects including behavioral deficits, 

### 16 morphological changes, and oxidative stress in the brains of rodents. In these rodent 

### 17 studies, interestingly, CNS effects were reported at O 3 concentrations that were generally 

### 18 lower than those concentrations commonly observed to produce pulmonary or cardiac 

### 19 effects in rats. 

### 20 A number of new studies demonstrate various perturbations in neurologic function or 

### 21 histology, including changes similar to those observed with Parkinson ’ s and Alzhei mer ’ s 

### 22 disease pathologies occurring in similar regions of the brain (Table 6

- 40). Many of these 

### 23 include exposure durations ranging from short

- term to long

- term, and as such are 

### 24 discussed here and in Chapter 7 with emphasis on the effects resulting from exp osure 

### 25 durations relevant to the respective chapter. Several studies assess short

- and long

- term 

### 26 memory acquisition via passive avoidance behavioral testing and find decrements in test 

### 27 performance after O 3 exposure, consistent with the aforementioned observ ation made in 

### 28 humans by Chen and Schwartz ( 2009 ) . Impairment of long

- term memory has been 

### 29 previously described in rats exposed to 0.2 ppm O 3 for 4 h ( Rivas

- Arancibia et al., 1998 ) 

### 30 and in other studies of 4

- hour exposure s at concentrations of 0.7 to 1 ppm ( Dorado



### 31 Martinez et al., 2001 ; Rivas

- Arancibia et al., 2000 ; Avila

- Costa et al., 1999 ) . More 

### 32 recently, st atistically significant decreases in both short and long

- term memory were 

### 33 observed in rats after 15 days of exposure to 0.25 ppm O 3 ( Rivas

- Arancibia et al., 2010 )

. 

### 34 The central nervous system is very sensitive to oxidative stre ss, due in part to its high 

### 35 content of polyunsaturated fatty acids, high rate of oxygen consumption, and low 

### 36 antioxidant enzyme capacity. Oxidative stress has been identified as one of the 

### 37 pathophysiological mechanisms underlying neurodegenerative disorder s such as 

### 38Draft

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- 186 September 2011 Parkinson ’ s and Alzheimer ’ s disease, among others ( Simonian and C oyle, 1996 ) . It is 

### 1 also believed to play a role in altering hippocampal function, which causes cognitive 

### 2 deficits with aging ( Van guilder and Freeman, 2011 ) . A particularly common finding in 

### 3 studies of O 3 - exposed rats is lipid peroxidation in the brain, especially in the 

### 4 hippocampus, which is important for higher cognitive function including contextual 

### 5 memory acquisition. Performa nce in passive avoidance learning tests is impaired when 

### 6 the hippocampus is injured, and the observed behavioral effects are well correlated with 

### 7 histological and biochemical changes in the hippocampus, including reduction in spine 

### 8 density in the pyramidal neurons ( Avila

- Costa et al., 1999 ) , lipoperoxidation ( Rivas



### 9 Arancibia et al., 2010 ; Dorado

- Martinez et al., 2001 ) , progressive neurodegeneration, and 

### 10 activated and phagocytic microglia ( Rivas

- Arancibia et al., 2010 ) . The hippocampus is 

### 11 also one of the main regions affected by age

- related neurodegenerative diseases, 

### 12 including Alzheimer ’ s disease, and it may be more sensitive to oxidative damage in aged 

### 13 rats. In a study of young ( 47 d ays ) and aged (900 d ays ) rats exposed to 1 ppm O 3 for 4 h, 

### 14 O 3 - induced lipid peroxidation occurred to a greater extent in the striatum of young rats, 

### 15 whereas it was highest in the hippocampus in aged rats ( Rivas

- Arancibia et al., 2000 )

. 

### 16 Martínez

- Canabal et al. ( 2008 ) showed exposure of rats to 0.25 ppm, 4h/day, for 7, 15, or 

### 17 30 days increased lipoperoxides in the hippocampus. This effect was observed at day 7 

### 18 and continued to increase with time, indicating cumulative oxidative damage. O 3 - induced 

### 19 changes in lipid peroxidation, neuronal death, and COX

- 2 positive cells in the 

### 20 hippocampus could be significantly inhibited by daily treatment with growth hormone 

### 21 (GH), which declines with age in most species. The protective effect of G H on

- induced 

### 22 oxidative stress was greatest at 15 days of exposure and was non

- significant at day 30. 

### 23 Consistent with these findings, lipid peroxidation in the hippocampus of rats was 

### 24 observed to increase significantly after a 30

- day exposure to 0.25 ppm , but not after a 

### 25 single 4

- h exposure to the same concentration ( Mokoena et al., 2010 ) . However, 4 hours 

### 26 of exposure was sufficient to cause significant increases in lipid peroxidation when the 

### 27 concentration was increased to 0.7 ppm, and another study observed lipid peroxidation 

### 28 after a 4

- h ex posure to 0.4 ppm ( Dorado

- Martinez et al., 2001 )

. 

### 29 Other commonly affected areas of the brain include the striatum, substantia nigra, 

### 30 cerebellum, olfactory bulb, and frontal/prefrontal cortex. The striatum and substantia 

### 31 nigra are particularly sensitive to oxidative stress because the metabolism of dopamine, 

### 32 central to their function, is an oxidative process perturbed by redox imbalance. Oxidative 

### 33 stress has been implicated in the premature death of substantia nigra dopamine neurons in 

### 34 Parkinson ’ s disease. Angoa

- Pérez et al. ( 2006 ) have shown progressive lipoperoxidation 

### 35 in the substantia nigra and a decrease in nigral dopamine neurons in ovariectomiz ed 

### 36 female rats exposed to 0.25 ppm O 3 , 4h/day, for 7, 15, or 30 days. Estradiol, an 

### 37 antioxidant, attenuated O 3 - induced oxidative stress and nigral neuronal death, and the 

### 38 authors note that in humans, estrogen therapy can ameliorate symptoms of Parkinson ’ s 

### 39Draft

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- 187 September 2011 disease, which is more prevalent in men. Progressive oxidative stress has also been 

### 1 observed in the striatum and substantia nigra of rats after 15 and 30 days of exposure to 

### 2 0.25 ppm O 3 for 4 h/day, along with a loss of dopaminergic neurons from the substa ntia 

### 3 nigra ( Pereyra

- Muñoz et al., 2006 ) . Decreases in motor activity were also observed at 15 

### 4 and 30 days of exposure, consistent with other reports ( Martrette et al., 2011 ; Dorado



### 5 Martinez et al., 2001 ) . Using a similar O 3 exposure protocol, Santiago

- López and 

### 6 colleagues ( 2010 ) also observed a progressive loss of dopaminergic neurons within the 

### 7 substantia nigra, accompanied by alterations in the morphology of remaining cells and an 

### 8 increase in p53 levels and nuclear translocat ion. 

### 9 The olfactory bulb also undergoes oxidative damage in O 3 exposed animals, in some 

### 10 cases altering olfactory

- dependent behavior. Lipid peroxidation was observed in the 

### 11 olfactory bulbs of ovariectomized female rats exposed to 0.25 ppm O 3 (4 h/day) for 3 0 or 

### 12 60 days ( Guevara

- Guzmán et al., 2009 ) . O 3 also induced decrements in a selective 

### 13 olfactory recognition memory test, and the authors note that early deficits in odor 

### 14 perception and memory are components of human neurodegenerative diseases. The 

### 15 decremen ts in olfactory memory were not due to damaged olfactory perception based on 

### 16 other tests. However, deficits in olfactory perception emerged with longer exposures 

### 17 (discussed in Chapter 7). As with the study by Angoa

- Pérez et al. ( 2006 ) described 

### 18 above, a prot ective effect for estradiol was demonstrated for both lipid peroxidation and 

### 19 olfactory memory defects. The role of oxidative stress in memory deficits and associated 

### 20 morphological changes has also been demonstrated via attenuation by other antioxidants 

### 21 as well, such as α

- tocopherol ( Guerrero et al., 1999 ) and taurine ( Rivas

- Arancibia et al., 

### 22 2000 )

. 

### 23 It is unclear how persistent these effects might be. One study of acute exposure, using 

### 24 1 ppm O 3 for 4 hours, observed morphological changes in the olfactory bulb of rats at 

### 25 2 hours, and 1 and 10 days, but not 15 days, after exposure ( Colín

- Barenque et al., 2005 )

. 

### 26 Other acute st udies also report changes in the CNS. Lipid peroxidation was observed in 

### 27 multiple regions of the brain after a 1

- to 9

- h exposure to 1 ppm O 3 ( Escalante

- Membrillo 

### 28 et al., 2005 ) . Ozone has also been shown to alter gene expression of endothelin

- 1 

### 29 (pituitary) and inducible nitric oxide synthase (cerebral hemispher e) after a single 4

- h 

### 30 exposure to 0.8 ppm O 3 , indicating potential cerebrovascular effects. This concentration



### 31 dependent effect was not observed at 0.4 ppm O 3 ( Thomson et al., 2007 ) . Vascular 

### 32 endothelial growth factor was upregulated in astroglial cells in the central respiratory 

### 33 areas of the brain of rats exposed to 0.5 ppm O 3 for 3 hours ( Araneda et al., 2008 ) . Th e 

### 34 persistence of CNS changes after a single exposure was also examined and the increase in 

### 35 vascular endothelial growth factor was present after a short (3 hours) recovery period. 

### 36 Thus, there is evidence that O 3 - induced CNS effects are both concentration

- a nd time



### 37 dependent. 

### 38Draft

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- 188 September 2011 Because O 3 can produce a disruption of the sleep

- wake cycle ( U.S. EPA, 2006b ) , Alfaro



### 1 Rodriguez et al. ( 2005 ) examined whether acetylcholine in a region of the brain involved 

### 2 in sleep regulation was altered by O 3 . After a 24

- h exposure to 0.5 ppm O 3 , the 

### 3 acetylcholine concentration in the medial preoptic area was decreased by 58% and 

### 4 strongly correlated with a disruption in paradoxical sleep. Such behavioral

- biochemical 

### 5 effects of O 3 are confirmed by a number of studies which have demonstrated 

### 6 morphological and biochemical changes in rats. 

### 7 CNS effects have also been demonstrated in newborn and adult rats whose only exposure 

### 8 to O 3 occurred in utero. Several neurotransmitters were assessed in male offspring of 

### 9 dams exposed to 1 ppm O 3 during the entire pregnancy ( Gonzalez

- Pina et al., 2008 ) . The 

### 10 data sho wed that catecholamine neurotransmitters were affected to a greater degree than 

### 11 indole

- amine neurotransmitters in the cerebellum. CNS changes, including behavioral, 

### 12 cellular, and biochemical effects, have also been observed after in utero exposure to 

### 13 0.5 p pm O 3 for 12 h/day from gestational days 5

- 20 ( Boussouar et al., 2009 ) . Tyrosine 

### 14 hydroxylase labeling in the nucleus tractus solatarius was increased after in utero 

### 15 exposure to O 3 whereas Fos protein labeling did not change. When these offspring were 

### 16 challenged by immobilization stress, neuroplasticity pathways, which were activated in 

### 17 air

- exposed offspring, were inhibited in O 3 - exposed offspring. Although an O 3 exposure 

### 18 concentra tion

- response was not studied in these two in utero studies, it has been 

### 19 examined in one study. Santucci et al. ( 2006 ) investigated behavioral effects and gene 

### 20 expression after in utero exposure of mice to as little as 0.3 ppm O 3 . Increased 

### 21 defensive/submissive behavior and reduced social investigation were observed in both the 

### 22 0.3 and 0.6 ppm O 3 groups. Changes in gene expression of brain

- derived neurotrophic 

### 23 factor (BDNF, increased in striatum) and nerve growth factor (NGF, decreased in 

### 24 hippocampus) accompanie d these behavioral changes. Thus, these three studies 

### 25 demonstrate that CNS effects can occur as a result of in utero exposure to O 3 , and 

### 26 although the mode of action of these effects is not known, it has been suggested that 

### 27 circulating lipid peroxidation pr oducts may play a role ( Boussouar et al., 2009 )

. 

### 28 Importantly, these CNS effects occurred in rodent models after in utero only exposure to 

### 29 relevant concentrations of O 3 . 

### 30Draft

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- 189 September 2011 

### Table 6 - 40 Central Nervous System and Behavioral Effects of Short - term O 3 

### 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 d ays , 6 h/d ay Significant 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 d ays , 4
- h/d ay , 5 days /wk 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 d ays , 4h/d ay Estradiol treatment protected against lipid peroxidation and decreases in estrogen receptors and dopamine β
- hydroxylase in olfactory bulbs along with deficits in olfacto ry recognition memory. Martínez
- Canabal et al. ( 2008 ) Rat; Wistar; M; Weight: 300g 0.25 7 to 30 d ays , 4
- h/d ay Growth 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 d ays , 4
- h/ d ay Decreased motor a ctivity, 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 to 90 d ays , 4
- h/ d ay Ozone produced significant 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 , and short
- and long
- term memory
- retention latency. Santiago
- López et al. ( 2010 ) Rat; Wistar; M; 250
- 300g 0.25 15, 30, and 60 d ays , 4
- h/d ay Progressive loss of dopamine reactivity in the substantia nigra, along with morphological changes. Increase d 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 post exposure At 0.8 ppm, O 3 produced rapid perturbations in the ET
- NO pathway gene expression in the brain. Ozone induced a small but significant time
- and concentration
- dependent increase in prepro
end othelin
- 1 mRNA levels in the cerebral hemisphere and pituitary, whereas TNFa and iNOS mRNA levels were decreased at 0 hrs and unchanged or increased, respectively, at 24 h. Alfaro
- Rodríguez and González
Pina ( 2005 ) Rat; Wistar; M; 292g 0.5 24
- h During the light phase, O 3 caused a significant decrease in paradoxical sleep accompanied by a significant 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 significant increase 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 cen ter of the brain. VEGF co
- located with IL
- 6 and TNF in cells near blood vessel walls, and blood vessel area was markedly increased. 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 12
- h/d ay ; 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 rat e was significantly increased in the heart and cerebral cortex and inhibited in the lung and striatum.Draft

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- 190 September 2011 Study Model O 3 ( ppm) Exposure Duration Effects Guzmán et al. ( 2006 ; 2005 ) Rat; Wistar; M; 21 days old; well
nourished and malnourished groups 0.75 15 successive d ays for 4
- h/d ay A significant 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 ozone in certain brain areas and the ozone
- 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 d ays , and 15 d ays after exposure A significant loss of dendritic spines in granule cells of the olfactory bulb occurred at 2 hrs to 10 d ays after ex posure. Cytological and ultrastructural changes returned towards normal morphology by 15 d ays
. Escalante
- Membrillo et al. ( 2005 ) Rats; Wistar; M; 280
- 320g 1.0 1
- , 3
- , 6
- , or 9
- h Significant increases in TBARS occurred in hypothalamus, cortex, striatum, midbrain, thalamus, and pons. Partial but significant recovery was observed by 3 h after the 9 h exposure. Gonzalez
- Pina et al. ( 2008 ) Rat; Wista r; M; 1 12
- h/d ay , 21 d ays of gestation; assays at 0, 5, & 10 d ays postnatal Prenatal O 3 exposure produced significant decreases in cerebellar monoamine but not indolamine. content at 0 and 5 d ays after birth with a partial recovery by 10 d. 5
- hydroxy
- indole
acetic acid levels were significantly increased at 10 d ays
.


### 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 and motor control, effects that may be responsible for some of the behavioral effects seen 

### 11 with O 3 exposure. A more recent study exposing immature female rats to 0.12 ppm O 3 

### 12 demonstrated significantly increased serum levels of the thyroid hor mone free T 3 after 15 

### 13 days of exposure, whereas free T 4 was unchanged ( Martrette et al., 2011 ) . These re sults 

### 14 are in contrast to those previously presented whereby 1 ppm O 3 for 1 day significantly 

### 15 decreased T 3 and T 4 ( Clemons and Garcia, 1980 ) , although comparisons are made 

### 16 difficult by hig hly disparate exposure regimens along with sex differences. Martrette et 

### 17 al. ( 2011 ) also demonstrated significantly increased corticosterone levels after 15 days of 

### 18 exposure, suggesting a stress related response. 

### 19Draft

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- 191 September 2011 

### 6.4.2 Summary and Causal Determination In rodents, O 3 exposure has been shown to cause physicochemical changes in the brain 

### 1 indicat ive of oxidative stress and inflammation. Newer toxicological studies add to earlier 

### 2 evidence that acute exposures to O 3 can produce a range of effects on the central nervous 

### 3 system and behavior. Previously observed effects, including neurodegeneration, 

### 4 al terations in neurotransmitters, short and long term memory, and sleep patterns, have 

### 5 been further supported by recent studies. In instances where pathology and behavior are 

### 6 both examined, animals exhibit decrements in behaviors tied to the brain regions or 

### 7 chemicals found to be affected or damaged. For example, damage in the hippocampus, 

### 8 which is important for memory acquisition, was correlated with impaired performance in 

### 9 tests designed to assess memory. Thus the brain is functionally affected by O 3 exposu re. 

### 10 The single epidemiologic study conducted showed an association between O 3 exposure 

### 11 and memory deficits in humans as well, albeit on a long

- term exposure basis. Notably, 

### 12 exposure to O 3 levels as low as 0.25 ppm for 7 days has resulted in progressive 

### 13 neu rodegeneration and deficits in both short and long

- term memory in rodents. 

### 14 Examination of changes in the brain at lower exposure concentrations or at 0.25 ppm for 

### 15 shorter durations has not been reported, but 0.12 ppm O 3 has been shown to alter 

### 16 behavior. It is possible that some behavioral changes may reflect avoidance of irritation 

### 17 as opposed to functional changes in brain morphology or chemistry, but in many cases 

### 18 functional changes are related to oxidative stress and damage. In some instances, changes 

### 19 wer e dependent on the nutritional status of the rats (high versus low protein diet). For 

### 20 example, O 3 produced an increase in glutathione in the brains of rats fed the high protein 

### 21 diet but decreases in glutathione in rats fed low protein chow ( Calderon Guzman et al., 

### 22 2006 ) . The hippocampus, one of the main regions affe cted by age

- related 

### 23 neurodegenerative diseases, appears to be more sensitive to oxidative damage in aged rats 

### 24 ( Rivas

- Arancibia et al., 2000 ) , and growth hormone, which declines with age in most 

### 25 species, may be protective ( Martínez

- Canabal and Angora

- Perez, 2008 ) . Developing 

### 26 animals may also be sensitive, as changes in the CNS, including biochemical, cellular, 

### 27 and behavioral effects, have been observed in juvenile and adult animals whose sole 

### 28 exposure occurred i n utero , at levels as a low as 0.3 ppm. A number of studies 

### 29 demonstrate ozone

- induced changes that are also observed in human neurodegenerative 

### 30 disorders such as Alzheimer ’ s and Parkinson ’ s disease, including signs of oxidative 

### 31 stress, loss of neurons/neur onal death, reductions in dopamine levels, increased COX

- 2 

### 32 expression, and increases in activated microglia in important regions of the brain 

### 33 (hippocampus, substantia nigra). 

### 34 Although evidence from epidemiologic and controlled human exposure studies is la cking, 

### 35 the toxicological evidence for ozone ’ s impact on the brain and behavior is strong, and at 

### 36Draft

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- 192 September 2011 least is suggestive of a causal relationship between O 3 exposure and effects on the 

### 1 central nervous syste m . 

### 2



## 6.5 Effects on Other Organ Systems

6.5.1 Effects on the Liver and Xenobiotic Metabolism Early investigations of the effects of O 3 on the liver centered on xenobiotic metabolism, 

### 3 and the prolongation of drug

- induced sleeping time, which was observed at 0.1 ppm O 3 

### 4 ( Graham et al., 1981 ) . In some species, only adults and especially females were affected. 

### 5 In rats, high (1.0

- 2.0 ppm for 3 hours) acute O 3 exposures caused increased production of 

### 6 NO by hepatocytes and enhanced protein synthesis ( Laskin et al., 1996 ; Laskin et al., 

### 7 1994 ) . Except for the earlier work on xenobiotic metabolism, the responses occurred only 

### 8 after very high acute O 3 exposures. One study, conducted at 1 ppm O 3 exposure, has been 

### 9 identified ( Last et al., 2005 ) in which alterat ions in gene expression underlying O 3 - 

### 10 induced cachexia and downregulation of xenobiotic metabolism were examined. A 

### 11 number of the down

- regulated genes are known to be interferon (IFN) dependent, 

### 12 suggesting a role for circulating IFN. A more recent study by Aibo et al. ( 2010 ) 

### 13 demonstrates exacerbation of acetaminophen

- induced liver injury in mice after a single 

### 14 6

- h exposure to 0.25 or 0.5 ppm O 3 . Data indicate that O 3 may worsen drug

- induced liver 

### 15 injury by inhibiting hepatic repair. The O 3 - associated effects shown in the liver are 

### 16 thought to be mediated by inflammatory cytokines or other cytotoxic mediators released 

### 17 by activated macrophages or other cells in the lungs ( Laskin and Laskin, 2001 ; Laskin et 

### 18 al., 1998 ; Vincent et al., 1996b ) . Recently, increased peroxidated lipids were detected in 

### 19 the plasma of O 3 exposed animals ( Santiago

- López et al., 201 0 )

. 

### 20 In summary, mediators generated by O 3 exposure may cause effects on the liver in 

### 21 laboratory rodents. Ozone exposures as low as 0.1 ppm have been shown to affect drug



### 22 induced sleeping time, and exposure to 0.25 ppm can exacerbate liver injury induced by a 

### 23 common analgesic. However, very few studies at relevant concentrations have been 

### 24 conducted, and no data from controlled human exposure or epidemiologic studies are 

### 25 currently available. Therefore the collective evidence is inadequate to determine if a 

### 26 causal relationship exists between short - term O 3 exposure and effects on the liver 

### 27 and metabolism. 

### 28Draft

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- 193 September 2011 

### 6.5.2 Effects on Cutaneous and Ocular Tissues In addition to the lungs, the skin is highly exposed to O 3 and contains O 3 reactive targets 

### 1 (polyunsaturated fatty a cids) that can produce lipid peroxides. The 2006 O 3 AQCD 

### 2 reported that although there is evidence of oxidative stress at near ambient O 3 

### 3 concentrations, skin and eyes are only affected at high concentrations (greater than 

### 4 1

- 5 ppm). Ozone exposure (0.8 ppm for 7 days) induces oxidative stress in the skin of 

### 5 hairless mice, along with proinflammatory cytokines ( Valacchi et al., 2009 ) . A recent 

### 6 study demonstrated that 0.25 ppm O 3 differentially alters expression of 

### 7 metalloproteinases in the skin of young and aged mice, indicating age

- related 

### 8 susc eptibility to oxidative stress ( Fortino et al., 2007 ) . In young mice, healing of skin 

### 9 wounds is no t significantly affected by O 3 exposure ( Lim et al., 2006 ) . However, 

### 10 exposure to 0.5 ppm O 3 for 6 h/day significantly delays wound closure in aged mice. As 

### 11 with effects on the liver described above, the effects of O 3 on the skin and eyes have no t 

### 12 been widely studied, and information from controlled human exposure or epidemiologic 

### 13 studies is not currently available. Therefore the collective evidence is inadequate to 

### 14 determine if a causal relationship exists between short - term O 3 exposure and 

### 15 effec ts on cutaneous and ocular tissues. 

### 16


## 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



### 17 and multicity studies, and meta

- analyses. In the large U.S. multicity studies that 

### 18 examined all

- year data, summary effect estimates corresponding to single

- day lags 

### 19 ranged from a 0.5

- 1% increase in all

- cause (nonaccidental) mortality per the standardized 

### 20 unit increase 1 in O 3 . The association between short

- term O 3 exposure and mortality was 

### 21 substantiated by a collection of meta

- analyses and international multicity studies. The 

### 22 studies evaluated found some evidence for heterogeneity in O 3 mortality risk estimates 

### 23 across cities and studies. Studies that conducted seas onal analyses, although more limited 

### 24 in number, reported larger O 3 mortality risk estimates during the warm or summer 

### 25 season. Overall, the 2006 O 3 AQCD identified robust associations between various 

### 26 measures of daily ambient O 3 concentrations and all

- cause mortality, with additional 

### 27 evidence for associations with cardiovascular mortality, which could not be readily 

### 28 explained by confounding due to time, weather, or copollutants. However, it was noted 

### 29

1 In the 2006 O 3 AQCD and throughout this document to compare across studies that used the same exposure metric, effect estimates were standardized to 40 ppb for 1
- h maximum, 30 ppb for 8
- h maximum, and 20 ppb for 24
- h average O 3 concentrations.Draft

– Do Not Cite or Quote 6
- 194 September 2011 that multiple uncertainties remain regarding the O 3 - mortal ity relationship including: the 

### 1 extent of residual confounding by copollutants; factors that modify the O 3 - mortality 

### 2 association; the appropriate lag structure for identifying O 3 - mortality effects (e.g., single



### 3 day lags versus distributed lag model); the s hape of the O 3 - mortality C

- R function and 

### 4 whether a threshold exists; and the identification of susceptible populations. Collectively, 

### 5 the 2006 O 3 AQCD concluded that “ the overall body of evidence is highly suggestive that 

### 6 O 3 directly or indirectly contrib utes to non

- accidental and cardiopulmonary

- related 

### 7 mortality. ” 

### 8

6.6.2 Associations of Mortality and Short - Term Ozone Exposure
The recent literature that examined the association between short

- term O 3 exposure and 

### 9 mortality further confirmed the associations repo rted in the 2006 O 3 AQCD. New 

### 10 multicontinent and multicity studies reported consistent positive associations between 

### 11 short

- term O 3 exposure and all

- cause mortality in all

- year analyses, with additional 

### 12 evidence for larger mortality risk estimates during th e warm or summer months (Figure 

### 13 6

- 27; Table 6

- 41). These associations were reported across a range of ambient O 3 

### 14 concentrations that were in some cases quite low (Table 6

- 42). 

### 15Draft

– Do Not Cite or Quote 6
- 195 September 2011 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 ozone concentrations. An “ a ” represent multicity studies and meta
- analyses from the 2006 ozone 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 ozone concentrations (see explanation in Section 6.2.7.2). 

### Figure 6 - 27 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; 57276) Bell et al. (2007; 93256) Schwartz (2005; 57333) Bell and Dominici (2008; 193828) Bell et al. (2004; 94417)a Levy et al. (2005; 74347)a Katsouyanni et al. (2009; 199899) Bell et al. (2005; 74345)a Ito et al. (2005; 74346)a Wong et al. (2010; 732535) Katsouyanni et al. (2009; 199899) Cakmak et al. (2011, 699135) Katsouyanni et al. (2009; 199899) Katsouyanni et al. (2009; 199899)b Samoli et al. (2009; 195855) Bell et al. (2004; 94417)a Schwartz (2005; 57333) Zanobetti and Schwartz (2008; 195755) Zanobetti and Schwartz (2008; 101596) Franklin and Schwartz (2008; 156448) Gryparis et al. (2004; 57276) Medina

- Ramon and Schwartz (2008) Katsouyanni et al. (2009; 199899) Bell et al. (2005; 74345)a Katsouyanni et al. (2009; 199899) Katsouyanni et al. (2009; 199899)b Levy et al. (2005; 74347)a Ito et al. (2005; 74346)a Katsouyanni et al. (2009; 199899) Stafoggia et al. (2010; 625034) 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 % IncreaseDraft

– Do Not Cite or Quote 6
- 196 September 2011 

### Table 6 - 41 Correspondi ng effect estimates for Figure 6 - 27 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. communit ies 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) Katsouyanni 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 ( 2008a ) 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
- Ramon an d 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. ( 2 005 ) 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 ) APHENA
- 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)

a Multicity studies and meta
- analyses from the 2006 O 3 AQCD. Bell et al. ( 2005 ) a , Ito e t al. ( 2005 ) a , and Levy et al. ( 2005 ) a 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
- 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
- 197 September 2011 

### Table 6 - 42 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 (NMMAPS) 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 Katsouyanni 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) 1990
- 1997 (June
- August) 8
- h max 20.0
- 62.8 75th: 27.2
- 74.8 Stafoggia et al. ( 2010 ) 10 Italian cities 2001
- 2005 (A pril
- 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 Zanobetti and Schwartz ( 2008a ) 48 U.S. cities c 1989
- 2000 (Winter: December
- February) (Spring: March
- May) (Summer: June
- August) (Autumn: September
November) 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/m3 by using the conversion factor of 0.51 assuming sta ndard 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 purpose s 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. CV=coefficient of variation 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 

### 3Draft

– Do Not Cite or Quote 6
- 198 September 2011 short

- term O 3 exposure and mortality presented across studies in the 2006 O 3 AQCD and 

### 1 supported in the new multicity studies, the following sections primarily focus on the 

### 2 examination of previously identified uncertainties in the O 3 - mortality relationship, 

### 3 specifically: O 3 associations with cause

- specific mortality, confounding, lag structure 

### 4 (e.g., multiday effects and mortality displacement), effect modification (i.e., sources of 

### 5 heterogeneity in risk estimates across cities); and the O 3 - mortality C

- R relationship. 

### 6 Focusing specifically on these uncertainties allow s for a more detailed characterization of 

### 7 the relationship between short

- term O 3 exposure and mortality. 

### 8

6.6.2.1 Confounding Recent epidemiologic studies examined potential confounders of the O 3 - mortality 

### 9 relationship. These studies specifically focused on whether PM and its constituents or 

### 10 seasonal trends confounded the association between short

- term O 3 exposure and 

### 11 mortality. 

### 12
Confounding by PM and PM C onstituents An important question in the evaluation of the association between short

- term O 3 

### 13 exposure and mortality is whether the relationship is confounded by particulate matter, 

### 14 particularly the PM chemical components that are found in the “ summer haze ” mixture 

### 15 which also contains O 3 . However, because of the temporal correlation among these PM 

### 16 components and O 3 , and their possible interactions, the interpretation of results from 

### 17 multipollutant models that attempt to disentangle the health effects associated with each 

### 18 pollutant is challenging. 

### 19 The potential confounding effects of PM 10 and PM 2.5 on the O 3 - mortality relationship 

### 20 were examined by Bell et al. ( 2007 ) using data on 98 U.S. urban communities for the 

### 21 years 1987

- 2000 from the National Morbidity, Mortality, and Air Pollution Study 

### 22 (NMMAPS). In this analysis the authors included PM as a covariate in time

- series 

### 23 models, and also e xamined O 3

- mo rtality associations on days when O 3 concentrations were 

### 24 below a specified value. This analysis was limited by the small fraction of days when 

### 25 both PM and O 3 data were available, due to the every

- 3rd

- or 6th

- day sampling schedule 

### 26 for the PM in dices, and the limited amount of city

- specific data for PM 2.5 because it was 

### 27 only collected in most cities since 1999. As a result, of the 91 communities with PM 2.5 

### 28 data, only 9.2% of days in the study period had data for both O 3 and PM 2.5 , resulting in 

### 29 th e use of only 62 communities in the PM 2.5 analysis. An examination of the correlation 

### 30 between PM (PM 10 and PM 2.5 ) and O 3 across various strata of daily PM 10 and PM 2.5 

### 31 concentrations found that neither PM size fraction was highly correlated with O 3 across 

### 32Draft

– Do Not Cite or Quote 6
- 199 September 2011 a ny of the strata examined. These results were also observed when using 8

- h max and 1

- h 

### 1 max O 3 exposure metrics. National and community

- specific effect estimates of the 

### 2 association between short

- term O 3 exposure and mortality were robust to inclusion of 

### 3 PM 1 0 or PM 2.5 in time

- series models through the range of O 3 concentrations (i.e., 

### 4 <10 ppb, 10

- 20, 20

- 40, 40

- 60, 60

- 80, and >80 ppb). For example, the percent increases in 

### 5 nonaccidental deaths per 10 ppb increase 24

- h avg O 3 concentrations at lag 0

- 1 day were 

### 6 0.22% (95% CI:

- 0.22, 0.65) without PM 2.5 and 0.21% (95% CI:

- 0.22, 0.64) with PM 2.5 

### 7 in 62 communities. 

### 8 Although no strong correlations between PM and O 3 were reported by Bell et al. ( 2007 ) 

### 9 the patterns observed suggest regional differences in their correlation. (Table 6

- 43). Both 

### 10 PM 10 and PM 2.5 show positive correlations with O 3 in the Industrial Midwest, Northeast, 

### 11 Urban Midwest, and Southeast, especially in the summer months, presumably, because of 

### 12 the summer peaking sulfate. However, the mostly negative or weak correlations between 

### 13 PM and O 3 in the summer in the Southwest, Northwest, and southern California could be 

### 14 due to winter

- peaking nitrate. Thus, the potential confounding effect of PM on the 

### 15 O 3 - mortality relationship could be influenced by the relative contribution of sulfate and 

### 16 nitrate , which varies regionally and seasonally. 

### 17

Table 6 - 43 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
- 200 September 2011 Source: Reprinted with permission of Informa UK Ltd ( Smith et al., 2009b )

. The diagonal line indicates 1:1 ratio. 

### Figure 6 - 28 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. The au thors conducted a number of analyses using 

### 3 constrained distributed lag models and the average of 0

- and 1

- day lags. In addition, 

### 4 Smith et al. ( 2009b ) examined the effect of different averaging times (24

- h, 8

- h, and 1

- h 

### 5 max) on O 3 - mortality regression coefficients, and whether PM 10 confounded the 

### 6 O 3 - mortality relationship. The authors reported that, in most cases, O 3 mortality risk 

### 7 estimates were reduced by between 22% and 33% in copollutant models with PM 10 . This 

### 8 is further highlighted in Figure 6

- 28, which shows scatter plots of O 3

- mo rtality risk 

### 9 estimates with adjustment for PM 10 versus without adjustment for PM 10 . Smith et al. 

### 10 ( 2009b ) point out that a larger fraction (89 out of 93) of the posterior estimates lie below 

### 11 the diagonal line (i.e., estimates are smaller with PM 10 adjustment) compared to the raw 

### 12 estimates (56 out of 93). This observation could be attributed to both sets of posterior 

### 13 estimates being calculated by “ shrinking towards the mean. ” However, the most 

### 14Draft

– Do Not Cite or Quote 6
- 201 September 2011 prominent feature of these plots is that the variation of O 3

- mo rtality risk estim ates across 

### 1 cities is much larger than the impact of PM 10 adjustment on the O 3

- mo rtality 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 overall 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 morta lity with a 10 ppb increase in same

- day 24

- h summertime O 3 concentrations across 

### 12 the 18 U.S. communities. Adjustment for PM 2.5 mass, which was available for 84% of the 

### 13 days, decreased the O 3

- mo rtality risk estimate only slightly (from 0.88% to 0.79%), but the 

### 14 inclusion of sulfate in the model reduced the risk estimate by 31% (from 0.85% to 

### 15 0.58%). However, sulfate data were only available for 18% of the days. Therefore, a 

### 16 limitation of this study is the limited amount of data for PM 2.5 chemical components d ue 

### 17 to the every

- 3rd

- day or every

- 6th

- day sampling schedule. For example, when using a 

### 18 subset of days when organic carbon measurements were available (i.e., 17% of the 

### 19 available days), O 3 mortality risk estimates were reduced to 0.51% (95% CI:

- 0.36 to 

### 20 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 confounding effects of 

### 23 copollutants on O 3 mortality risk estimates is not straightforward. As presented in Figure 

### 24 6

- 29, the regional and city

- to

- city variations in O 3 mortality r isk estimates appear greater 

### 25 than the impact of adjusting for copollutants. In addition, in some cases, a negative O 3 

### 26 mortality risk estimate becomes even more negative with the inclusion of sulfate (e.g., 

### 27 Seattle) in a copollutant model, or a null O 3 mort ality risk estimate becomes negative 

### 28 when sulfate is included (e.g., Dallas and Detroit). Thus, the reduction in the overall O 3 

### 29 mortality risk estimate (i.e., across cities) needs to be assessed in the context of the 

### 30 heterogeneity in the single

- city estima tes. 

### 31Draft

– Do Not Cite or Quote 6
- 202 September 2011 Source: Reprinted from Franklin and Schwartz ( 2008 )

. 

### Figure 6 - 29 Community - specific ozone - mortality risk estimates for nonaccidental mortality per 10 ppb increase in same - day 24 - h avg summertime ozone concentrations in single - pollutant models and copollutant models with sulfate.
In the APHENA study, the investigators from the U.S. (NMMAPS), Canadian, an d 

### 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 citi es 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 years 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 fo r comparison purposes, but only the NS 

### 10 results are presented in figures because alternative spline models have previously been 

### 11 shown to result in similar effect estimates ( HEI, 2003 ) . Additionally, for the Canadian 

### 12 results, figures contain risk estimates standardized to both a 40 ppb increment for 1

- h 

### 13Draft

– Do Not Cite or Quote 6
- 203 September 2011 max O 3 concentrations, consist ent with the rest of the ISA, but also the approximate IQR 

### 1 across the Canadian cities as discussed previously (Section 6.2.7.2). 

### 2 In the three datasets, the authors found generally positive associations between short

- term 

### 3 O 3 exposure and all

- cause, cardiov ascular, and respiratory mortality. The estimated 

### 4 excess risks for O 3 were larger for the Canadian cities than for the U.S. and European 

### 5 cities. When examining the potential confounding effects of PM 10 on O 3 mortality risk 

### 6 estimates, the sensitivity of the estimates varied across the data sets and age groups. In 

### 7 the Canadian dataset, adjusting for PM 10 modestly reduced O 3 risk estimates for all

- cause 

### 8 mortality for all ages in the PS (4.5% [95% CI: 2.2, 6.7%]) and NS (4.2% [95% CI: 1.9, 

### 9 6.5%]) models to 3.8% (95% CI:

- 1.4, 9.8%) and 3.2% (95% CI:

- 2.2, 9.0%), 

### 10 respectively, at lag 1 for a 40 ppb increase in 1

- h max O 3 concentrations (Figure 6

- 30; 

### 11 Table 6

- 44). However, adjusting for PM 10 reduced O 3 mortality risk estimates in the ≥ 

### 12 75

- year age group, but increa sed the risk estimates in the <75

- year age group. For 

### 13 cardiovascular and respiratory mortality more variable results were observed with O 3 risk 

### 14 estimates being reduced and increased, respectively, in copollutant models with PM 10 

### 15 (Figure 6

- 30; Table 6

- 44). Unlike the European and U.S. datasets, the Canadian dataset 

### 16 only conducted copollutant analyses at lag 1; as a result, to provide a comparison across 

### 17 study locations only the lag 1 results are presented for the European and U.S. datasets in 

### 18 this section. 

### 19 In the European data, O 3 risk estimates were robust when adjusting for PM 10 in the year



### 20 round data for all

- cause, cardiovascular and respiratory mortality. When restricting the 

### 21 analysis to the summer months moderate reductions were observed in O 3 risk esti mates 

### 22 for all

- cause mortality with more pronounced reductions in respiratory mortality. In the 

### 23 U.S. data, adjusting for PM 10 moderately reduced O 3 risk estimates for all

- cause mortality 

### 24 in a year

- round analysis at lag 1 (e.g., both the PS and NS models wer e reduced from 

### 25 0.18% to 0.13%) (Figure 6

- 30; Table 6

- 44). Similar to the European data, when 

### 26 restricting the analysis to the summer months, adjusting for PM 10 moderately reduced O 3 

### 27 mortality risk estimates in the U.S. However, when examining cause

- specific mortality 

### 28 risk estimates, consistent with the results from the Canadian dataset, which employed a 

### 29 similar PM sampling strategy (i.e., every

- 6th

- day sampling), O 3 risk estimates for 

### 30 cardiovascular and respiratory mortality were more variable; reduced or in creased in 

### 31 all

- year and summer analyses. Overall, the estimated O 3 risks appeared to be moderately 

### 32 to substantially sensitive to inclusion of PM 10 in copollutant models. Despite the multicity 

### 33 approach, the mostly every

- 6th

- day sampling schedule for PM 10 in the Canadian and U.S. 

### 34 datasets greatly reduced the sample size and limits the interpretation of these results. 

### 35Draft

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- 204 September 2011 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 natural spli nes. 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 = respiratory mortality. An “ a ” 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 - 30 Percent increase in all - cause (nonaccidental) and cause - specific mortality from the APHENA study for single - and copollutant 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 % IncreaseDraft

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- 205 September 2011 

### Table 6 - 44 Corresponding Effect Estimates for Figure 6 - 30 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
- 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 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 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 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 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 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 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 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)

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 

### 2Draft

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- 206 September 2011 2001 to 2005. In a time

- stratified ca se - crossover analysis, using data for the summer 

### 1 months (i.e., April

- September), the authors examined O 3 - mortality associations across 

### 2 each city, and then obtained a pooled estimate through a random

- effects meta

- analysis. 

### 3 Stafoggia et al. ( 2010 ) found a strong association with nonaccidental mortality (9.2% 

### 4 [95% CI: 5.4, 13.0%] for a 30 ppb increase in 8

- h max O 3 concentrations) in an 

### 5 unconstrained distributed lag model (la g 0

- 5) that persisted in copollutant models with 

### 6 PM 10 (9.2% [95% CI: 5.4, 13.7%]). Additionally, when examining cause

- specific 

### 7 mortality, the authors found positive associations between short

- term O 3 exposure and 

### 8 cardiovascular (14.3% [95% CI: 6.7, 22.4%]) , cerebrovascular (8.5% [95% CI: 0.1, 

### 9 16.3%]), and respiratory (17.6% [95% CI: 1.8, 35.6%]) mortality in single

- pollutant 

### 10 models. In copollutant models, O 3 - mortality effect estimates for cardiovascular and 

### 11 cerebrovascular mortality were robust to the inclu sion of PM 10 (9.2% [95% CI: 5.4, 

### 12 13.7%]) and 7.3% [95% CI:

- 1.2, 16.3%], respectively), and attenuated, but remained 

### 13 positive, for respiratory mortality (9.2% [95% CI:

- 6.9, 28.8%]). Of note, the correlations 

### 14 between O 3 and PM 10 across cities were found to be generally low, ranging from (

- 0.03 to 

### 15 0.49). The authors do not specify the sampling strategy used for PM 10 in this analysis. 

### 16
Confounding by Seasonal Trend The APHENA study ( Katsouyanni et al., 2009 ) , mentioned abo ve, also conducted 

### 17 extensive sensitivity analyses to identify the appropriate: smoothing method and basis 

### 18 functions to estimate smooth functions of time in city

- specific models; and degrees of 

### 19 freedom to be used in smooth functions of time, to adjust for s easonal trends. Because O 3 

### 20 peaks in the summer and mortality peaks in the winter, not adjusting or not sufficiently 

### 21 adjusting for the seasonal trend would result in an apparent negative association between 

### 22 the O 3 and mortality time

- series. Katsouyanni et a l. ( 2009 ) examined the effect of the 

### 23 extent of smoothing for seasonal trends by using models with 3 df/year, 8 df/year (the 

### 24 choice for their main model), 12 df/year, and df/year selected using the sum of absolute 

### 25 values of pa rtial autocorrelation function of the model residuals (PACF) (i.e., choosing 

### 26 the degrees of freedom that minimizes positive and negative autocorrelations in the 

### 27 residuals). Table 6

- 45 presents the results of the degrees of freedom analysis using 

### 28 alternativ e methods to calculate a combined estimate: the Berkey et al. ( 1998 ) meta



### 29 regression and the two

- level normal independent sampling estimation (TLNISE) 

### 30 hierarchical method. The results show that the methods used to combine single

- city 

### 31 estimates did not infl uence the overall results, and that neither 3 df/year nor choosing the 

### 32 df/year by minimizing the sum of absolute values of PACF of regression residuals was 

### 33 sufficient to adjust for the seasonal negative relationship between O 3 and mortality. 

### 34 However, it sh ould be noted, the majority of studies in the literature that examined the 

### 35 mortality effects of short

- term O 3 exposure, particularly the multicity studies, used 7 or 

### 36Draft

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- 207 September 2011 8 df/year to adjust for seasonal trends, and in both methods a positive association was 

### 1 ob served between O 3 exposure and mortality. 

### 2

Table 6 - 45 Sensitivity of ozone risk estimates per 10 μg/m 3 

### increase in 24 - h avg ozone concentrations at lag 0 - 1 to alternative methods for adjustment of seasonal trend, for all - cause mortality using Berkey MLE an d TLNSE 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 ( 2009 )

.


### 6.6.2.2 Effect Modification
There have been several multicity studies that examined potential effect modifiers , or 

### 3 time

- invariant factors, that m ay modify O 3 mortality risk estimates. These effect 

### 4 modifiers can be categorized into either individual

- level or community

- level 

### 5 characteristics , which are traditionally, examined in second stage regression model s . The 

### 6 results from these analyses also inform upon whether certain populations are susceptible 

### 7 to O 3 - related health effects (Chapter 8). In addition to potentially modifying the 

### 8 association between short

- term O 3 exposure and mortality, b oth individual

- level and 

### 9 community

- level characteristics may also contribute to the apparent geographic pattern of 

### 10 spatial heterogeneity in O 3 mortality risk estimates. As a result, the geographic pattern of 

### 11 O 3 mortality risk estimates is also evaluated in this section

. 

### 12

Indi vidual - Level Characteristics Medina

- Ramón and Schwartz ( 2008 ) conducted a case

- only study in 48 U.S. cities to 

### 13 identify populations potential ly susceptible to O 3 - related mortality for the period 

### 14 1989

- 2000 (May through September of each year [i.e., warm season]). A case

- only 

### 15 design predicts the occurrence of time

- invariant characteristics among cases as a function 

### 16 of the exposure level ( Armstrong, 2003 ) . For each potential effect modifier (time



### 17 invariant individual

- level characteristics), city

- specific logistic regression models we re 

### 18 fitted, and the estimates were pooled across all cities. Furthermore, the authors examined 

### 19 potential differences in individual effect modifiers according to several city 

### 20 characteristics (e.g., mean O 3 level, mean temperature, households with central air 

### 21Draft

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- 208 September 2011 conditioning, and population density) in a meta

- regression. Across cities the authors 

### 1 found a 1.96% (95% CI: 1.14

- 2.82%) increase in mortality at lag 0

- 2 for a 30 ppb 

### 2 increase in 8

- h max O 3 concentrations. Additionally, Medina

- Ramón and Schwartz 

### 3 ( 2008 ) examined a number of individual

- level characteristics (e.g., age, race) and chronic 

### 4 conditions (e.g., secondary causes of death) as effect modi fiers of the association between 

### 5 short

- term O 3 exposure and mortality. The authors found that older adults (i.e., ≥ 65), 

### 6 women >60 years of age, black race, and secondary atrial fibrillation showed the greatest 

### 7 additional percent change in O 3 - related morta lity (Table 6

- 4 6 ). In addition, when 

### 8 examining city

- level characteristics, the authors found that older adults, black race, and 

### 9 secondary atrial fibrillation had a larger effect on O 3 mortality risk estimates in cities with 

### 10 lower O 3 levels. Of note, a similar case

- only study ( Schwartz, 2005b ) examined potential 

### 11 effect modifiers of the association between temperature and mortality, which would be 

### 12 expected to find results consistent with the Medina

- Ramón and Schwartz ( 2008 ) study 

### 13 due to the high correlation between temperature and O 3 . However, when stratifying days 

### 14 by temperature Schwartz ( 2005b ) found strong evid ence that diabetes modified the 

### 15 temperature

- mortality association on hot days, which was not as evident when examining 

### 16 the O 3 - mortality association in Medina

- Ramón and Schwartz ( 2008 ) . This difference 

### 17 could be due to the study design and populations included in both studies, a multicity 

### 18 study including all ages ( Medina

- Ramón and Schwartz, 2008 ) compared to a single

- city 

### 19 study of individuals ≥ 65 years of age ( Schwartz, 2005b ) . However, when examining 

### 20 results stratified by race, nonwhites were found to have higher mortal ity risks on both hot 

### 21 and cold days, which provide some support for the additional risk found for black race in 

### 22 Medina

- Ramón and Schwartz ( 2008 )

. 

### 23 Individual

- level factors that may result in susceptibility to O 3 - related mortality were also 

### 24 examined by Stafoggia et al. ( 2010 ) . As discussed above, using a time

- stratified case



### 25 crossover analysis, the authors found an association between short

- term O 3 exposure and 

### 26 nonaccidental mortality in an unconstrained distributed lag model in 10 Italian cities 

### 27 (9.2% [95% CI: 5.4, 13.0%; lag 0

- 5 for a 30 ppb increase in 8

- h max O 3 concentrations). 

### 28 Stafoggia et al. ( 2010 ) conducted additional analyses to examine whether age, sex, 

### 29 income level, location of death, and underlying chronic con ditions increased the risk of 

### 30 O 3 - related mortality, but data were only available for nine of the cities for these analyses. 

### 31 Of the individual

- level factors examined, the authors found the strongest evidence for 

### 32 increased risk of O 3 - related mortality in ind ividuals ≥ 85 years of age (22.4% [95% CI: 

### 33 15.0, 30.2%]), women (13.7% [95% CI: 8.5, 19.7%]), and out

- of

- hospital deaths (13.0% 

### 34 [95% CI: 6.0, 20.4%]). When focusing specifically on out

- of hospital deaths and the 

### 35 subset of individuals with chronic condition s, Stafoggia et al. ( 2010 ) found the strongest 

### 36 association for individuals with diabetes, which is consistent with the potentially 

### 37 increased susceptibility of diabetics o n hot days observed in Schwartz ( 2005b )

. 

### 38Draft

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- 209 September 2011 

### Table 6 - 4 6 Additional percent change in ozone - related mortality for individual level susceptibility factors 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 increased 10 ppb. These values were not standardized because they do not represent the actual effect estimate for the characteristic being evaluated, but instead, th e difference between effect estimates for persons with versus without the condition. b Compared with males in the same age group.

Source: Reprinted with permission from 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 constrain ed 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 to 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 not significantly 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 examination of the influence of SES indicators (i.e., educational attainment, income level, 

### 10 and employment status) on the O 3 - mortality relationship. The authors found the largest 

### 11 risk estima tes in the lowest SES categories for each of the indicators examined this 

### 12 includes: primary school not completed when examining educational attainment; the 

### 13 lowest quartile of income level; and unemployed individuals when comparing 

### 14 employment status. 

### 15 Overa ll, uncertainties exist in the interpretation of the potential effect modifiers, 

### 16 identified in Medina

- Ramón and Schwartz ( 2008 ) , Stafoggia et al. ( 2010 ) , and Cakmak et 

### 17Draft

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- 210 September 2011 al. ( 2011 ) of the O 3 - mo rtality relationship due to the expected heterogeneity in O 3 mortal



### 1 ity risk estimates across cities as highlighted in Smith et al. ( 2009b ) (Figure 6

- 28) and 

### 2 Franklin and Schwartz ( 2008 ) (Figure 6

- 29). For example, it is difficult to determine the 

### 3 relative importance of a susceptibility factor that results in an additional percent increase 

### 4 in mortality in a multicity analysis when analyses of the individual cities within the study 

### 5 did not indicate associations between O 3 and mortality. In addition, it is likely that 

### 6 individual

- level susceptibility factors identified in Medina

- Ramón and Schwartz ( 2008 ) , 

### 7 Stafogg ia et al. ( 2010 ) , and Cakmak et al. ( 2011 ) only modify the O 3 - mo rtality relation



### 8 ship. The factors identified span pollutants as is evident by older adults (i.e., ≥ 65) often 

### 9 being identified as an effect modifier of PM mortality risk estimates ( U.S. EPA, 2009d )

. 

### 10
Community - level Characteristics Several studies also examined city

- level (i.e., ecological) variables to explain city

- to

- city 

### 11 variation in estimated O 3 mortality risk estimates. Bell and Dominici ( 2008 ) investigated 

### 12 whether community

- level characteristics, such as race, income, education, urbanization, 

### 13 transportation use, PM and O 3 levels, number of O 3 monitors, weather, and air 

### 14 conditioning use could explain the heterogeneity in O 3 - mortality ri sk estimates across 

### 15 cities. The authors analyzed 98 U.S. urban communities from NMMAPS for the period 

### 16 1987

- 2000. In the all

- year regression model that included no community

- level variables, 

### 17 a 20 ppb increase in 24

- h avg O 3 concentrations during the previou s week was associated 

### 18 with a 1.04% (95% CI: 0.56, 1.55) increase in mortality. Bell and Dominci ( 2008 ) fou nd 

### 19 that higher O 3

- mo rtality effect estimates were associated with higher: percent 

### 20 unemployment, fraction of the population Black/African

- American, percent of the 

### 21 population that take public transportation to work; and with lower: temperatures and 

### 22 percent o f households with central air conditioning (Figure 6

- 31). The modification of 

### 23 O 3 - mortality risk estimates reported for city

- specific temperature and prevalence of 

### 24 central air conditioning in this analysis confirm the result from the meta

- analyses 

### 25 reviewed in the 2006 O 3 AQCD. 

### 26 The APHENA project ( Katsouyanni et al., 2009 ) examined potential effect modification 

### 27 of O 3 risk estimates in the Canadian, European, and U.S. data sets using a consistent set 

### 28 of cit y - specific variabl es. Table 6

- 47 presents the results from all age analyses for all



### 29 cause mortality using all

- year O 3 data for the average of lag 0

- 1 day. While there are 

### 30 several significant effect modifiers in the U.S. data, the results are mostly inconsistent 

### 31 with the res ults from the Canadian and European data sets. The positive effect 

### 32 modification by percentage unemployed and the negative effect modification by mean 

### 33 temperature (i.e., a surrogate for air conditioning rate) are consistent with the results 

### 34 reported by Bell and Dominici ( 2008 ) discussed above. However, the lack of consistency 

### 35 across the data sets, even between the Canadian and U.S. data, makes it difficult to 

### 36Draft

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- 211 September 2011 interpret the results. Some of these associations may be due to coincidental correlations 

### 1 with other unmeasured factors that vary regionally (e.g., mean SO 2 tend to be higher in 

### 2 the eastern U.S.). 

### 3

Source: Reprinted with permission of Johns Hopkins Bloomberg School of Public Health, Bell and Dominici ( 2008 )

. 

### Figure 6 - 31 Ozone mortality risk estimates and community - specific characteristics, U.S., 1987 - 2000. 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.Draft

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- 212 September 2011 

### Table 6 - 4 7 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 cen ter - specific distribution of selected effect modifiers 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

- mo rtality association, studies also examined whether these associations varie d 

### 2 regionally within the U.S. Bell and Dominici ( 2008 ) , in the study discussed above, also 

### 3 noted that O 3 - mo rtality risk estimates 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

- 4 8 ). 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 (Figure 6

- 

### 8 32). It is worth noting that in the analysis of PM 10 using the same data set, Peng et al. 

### 9 ( 2005 ) also found that both the Northeast and Industrial Midwest showed particularly 

### 10Draft

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- 213 September 2011 elevated effects, especially during the summer months. As mentioned above, although no 

### 1 evidence for confounding of O 3 mortality risk estimates by PM 10 was observed, Bell et al. 

### 2 ( 2007 ) did find regional differences in the correlation between O 3 and PM 10 . Thus, the 

### 3 heterogeneity in O 3 mortality risk estimates may n eed to be examined as a function of the 

### 4 correlation between PM and O 3 . 

### 5 Smith et al. ( 2009b ) , as discussed earlier, also examined the regional differe nce in O 3 

### 6 mortality risk estimates across the same seven regions and similarly found evidence for 

### 7 regional heterogeneity. In addition, Smith et al. ( 2009 b ) constructed spatial maps of the 

### 8 risk estimates by an extension of a hierarchical model that allows for spatial auto



### 9 correlation among the city

- specific random effects. Figure 6

- 31 presents the spatial map 

### 10 of O 3 mortality coefficients from the Smith e t al. ( 2009b ) analysis that used 8

- h max O 3 

### 11 concentrations during the summer. The results from the Bell and Dominici ( 2008 ) 

### 12 analysis (Figure 6

- 32) shows much stronger apparent heterogeneity in O 3 - mortality risk 

### 13 estimates across cities than the smoothed map from Smith et al. ( 2009b ) (Figure 6

- 33), 

### 14 but both maps generally show larger risk estimates in the eastern region of the U.S. 

### 15

Table 6 - 4 8 Percentage increase in daily mortality for a 10 ppb increase in 24 - h avg ozone concentrations during the previous week by geographic region in the U.S., 1987 - 2000
No. of Communities Regional 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 southern 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: Used with permission from Johns Hopkins Bloomberg School of Public Health, Bell and Dominici ( 2008 )

.Draft

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- 214 September 2011 Source: Reprinted with permission of Johns Hopkins Bloomberg School of Public Health ( Bell and Dominici, 2008 )

. 

### Figure 6 - 32 Community - specific Bayesian ozone - mortality risk estimates in 98 U.S. communities.

Source: Reprinted with permission of Informa UK Ltd. ( Smith et al., 2009b )

. 

### Figure 6 - 33 Map of spatially dependent ozone - mortality coefficients for 8 - h max ozone concentrations using summer data.Draft

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- 215 September 2011 

### 6.6.2.3 Interaction
The terms effect modifica tion and interaction are often used interchangeably, but 

### 1 theoretically they represent different concepts. Although interactions can lead to either 

### 2 antagonistic or synergistic effects, most studies attempt to identify potential factors that 

### 3 interact synergi stically with O 3 to increase the risk of mortality. Within this section, 

### 4 interactive effects are defined as time

- varying covariates, such as temperature and 

### 5 copollutants that are included in 1st stage time

- series regression models. To date, only a 

### 6 few time

- series studies have investigated the potential interaction between O 3 exposure 

### 7 and copollutants or weather variables. This can be attributed to the moderate to high 

### 8 correlation between O 3 and these covariates, which makes such investigations 

### 9 methodologica lly challenging. 

### 10 Ren et al. ( 2008 ) examined the possible synergistic effect between O 3 and temperature on 

### 11 mortality in the 60 largest eastern U.S. communities from the NMMAPS data during the 

### 12 warm months (i.e., April to October) from 1987

- 2000. This analysis was restricted to the 

### 13 eastern areas of the U.S. (i.e., Northeast, Industrial Midwest and Southeast) because a 

### 14 previous study which focused specifically on the eastern U.S. found that 

### 15 temper ature

- mortality patterns differ between the northeast and southeast regions 

### 16 possibly due to climatic differences ( Curriero et al., 2002 ) . To examine possible 

### 17 geographic differences in the interaction between temperature and O 3 , Ren et al. ( 2008 ) 

### 18 further divided the NMMAPS regions into the Northeast, which included the Northeast 

### 19 and Industrial Midwest regions (34 cities), and the Southeast, which included the 

### 20 Southeast region (26 cities). The potential synergistic effects between O 3 and te mperature 

### 21 were examined using two different models. Model 1 included an interaction term in a 

### 22 Generalized Additive Model (GAM) for O 3 and maximum temperature (3

- day avg values 

### 23 were used for both terms) to examine the bivariate response surface and the patt ern of 

### 24 interaction between the two variables in each community. Model 2 consisted of a 

### 25 Generalized Linear Model (GLM) that used interaction terms to stratify by “ low, ” 

### 26

“ moderate, ” and “ high ” temperature days using the first and third quartiles of temperatu re 

### 27 as cut

- offs to examine the percent increase in mortality in each community. Furthermore, 

### 28 a two

- stage Bayesian hierarchical model was used to estimate the overall percent increase 

### 29 in all

- cause mortality associated with short

- term O 3 exposure across tempe rature levels 

### 30 and each region using model 2. The same covariates were used in both model 1 and 2. 

### 31 The bivariate response surfaces from model 1 suggest possible interactive effects 

### 32 between O 3 and temperature although the interpretation of these results is n ot 

### 33 straightforward due to the high correlation between these terms. The apparent interaction 

### 34 between temperature and O 3 as evaluated in model 2 varied across geographic regions. In 

### 35 the northeast region, a 20 ppb increase in 24

- h avg O 3 concentrations at la g 0

- 2 was 

### 36 associated with an increase of 4.49% (95% posterior interval [PI]: 2.39, 6.36%), 6.21% 

### 37Draft

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- 216 September 2011 (95% PI: 4.47, 7.66%) and 12.8% (95% PI: 9.77, 15.7%) in mortality at low, moderate 

### 1 and high temperature levels, respectively. The corresponding percent increa ses in 

### 2 mortality in the southeast region were 2.27% (95% PI:

- 2.23, 6.46%) for low temperature, 

### 3 3.02% (95% PI: 0.44, 5.70%) for moderate temperature, and 2.60% (95% PI:

- 0.66, 

### 4 6.01%) for high temperature. 

### 5 When examining the relationship between temperature and O 3 - related mortality, the 

### 6 results reported by Ren et al. ( 2008 ) (i.e., higher O 3 - mortality risks on days with higher 

### 7 temperatures) may appear to contradict the results of Bell and Dominic i ( 2008 ) described 

### 8 earlier (i.e., communities with higher temperature have lower O 3 - mortality risk 

### 9 estimat es). However, the observed difference in results can be attributed to the 

### 10 interpretation of effect modification in a second

- stage regression which uses long

- term 

### 11 average temperatures, as was performed by Bell and Dominici ( 2008 ) , compared to a 

### 12 first

- stage regression that examines the interaction between daily temperature and O 3 - 

### 13 related mortality. In this case, the second

- stage regression results from Bell and Dominici 

### 14 ( 2008 ) indicate that a city with lower tempera tures, on average, tend to show a stronger 

### 15 O 3 mortality effect, whereas, in the first

- stage regression performed by Ren et al. ( 2008 ) , 

### 16 the days with higher temperature tend to show a larger O 3 - mortality effect. This observed 

### 17 difference may in part reflect the higher air conditioning use in communities with higher 

### 18 long

- term average temperatures. Therefore, the findings from Ren et al. ( 2008 ) indicating 

### 19 generally lower O 3 risk estimates in the southeast region where the average temperature is 

### 20 higher than in the northeast region is consistent with the regional results reported by Bell 

### 21 and Dominici ( 2008 ) . As demonstrated by the results from both Ren et al. ( 2008 ) and 

### 22 Bell an d Dominici ( 2008 ) caution is required when interpreting results from studies that 

### 23 examined interactive eff ects using two different approaches because potential effect 

### 24 modification as suggested in a second

- stage regression generally does not provide 

### 25 evidence for a short

- term interaction examined in a first

- stage regression. Overall, further 

### 26 examination of the p otential interactive (synergistic) effects of O 3 and covariates in time



### 27 series regression models is required to more clearly understand the factors that may 

### 28 influence O 3 mortality risk estimates. 

### 29

6.6.2.4 Evaluation of the Ozone - Mortality C - R Relationship and Relat ed Issues
Evaluation of the O 3 - mortality concentration

- response relationship is not straightforward 

### 30 because the evidence from multicity studies (using log

- linear models) suggests that 

### 31 O 3 - mortality associations are highly heterogeneous across regions. In ad dition, there are 

### 32 numerous issues that may influence the shape of the O 3 - mortality concentration

- response 

### 33 relationship that warrant examination including: multi

- day effects (distributed lags), 

### 34Draft

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- 217 September 2011 potential adaptation, mortality displacement (i.e., hastening o f death by a short period), 

### 1 and the exposure metric used to compute risks (e.g., 1

- h daily max versus 24

- h avg). The 

### 2 following section presents the recent studies identified that conducted an initial 

### 3 examination of these issues. 

### 4
Multiday Effects, Mortality Displacement, and Adaptation The pattern of positive lagged associations followed by negative associations in a 

### 5 distributed lag model may be considered an indication of “ mortality displacement ” (i.e., 

### 6 deaths are occurring in frail individuals and exposure is only moving the day of death to a 

### 7 day slightly earlier). Zanobetti and Schwartz ( 2008b ) examined this issue in 48 U.S. cities 

### 8 during the warm season (i.e., June

- August) for the years 1989

- 2000. In an initial analysis, 

### 9 the authors ap plied a GLM to examine same

- day O 3 - mortality effects, and in the model 

### 10 included an unconstrained distributed lag for apparent temperature to take into account 

### 11 the effect of temperature on the day death occurred and the previous 7 days. To examine 

### 12 mortality displacement Zanobetti and Schwartz ( 2008b ) refit models using two 

### 13 approaches: an unconstrained and a smooth distributed lag each with 21

- day lags for O 3 . 

### 14 In this study, all

- cause mortality as well as cause

- specific mortality (i.e., cardiovascular, 

### 15 respiratory, and stroke) were examined for evidence of mortality displacement. The 

### 16 authors found a 0.96% (95% CI: 0.60, 1.30%) increase in all

- cause mortality across all 48 

### 17 cities for a 30 ppb increase in 8

- h max O 3 concentrations at lag 0 whereas the combined 

### 18 estimate of the unconstrained distributed lag model (lag 0

- 20) was 1.54% (95% CI: 0.15, 

### 19 2.91%). Similarly, when examining the cause

- specific mortality results (Table 6

- 4 9 ), 

### 20 larger risk estimates were observed for the distributed lag mo del compared to the lag 

### 21 0 day estimates. However, for stroke a slightly larger effect was observed at lags 4

- 20 

### 22 compared to lags 0

- 3 suggesting a larger window for O 3 - induced stroke mortality. This is 

### 23 further supported by the sum of lags 0 through 20 days showing the greatest effect. 

### 24 Overall, these results suggest that estimating the mortality risk using a single day of O 3 

### 25 exposure may underestimate the public health impact, but the extent of multi

- day effects 

### 26 appear to be limited to a few days. This is fur ther supported by the shape of the combined 

### 27 smooth distributed lag (Figure 6

- 34). It should be noted that the proportion of total 

### 28 variation in the effect estimates due to the between

- cities heterogeneity, as measured by 

### 29 I 2 statistic, was relatively low (4% for the lag 0 estimates and 21% for the distributed 

### 30 lag), but 21 out of the 48 cities exhibited null or negative estimates. As a result, the 

### 31 estimated shape of the distributed lag cannot be interpreted as a general form of lag 

### 32 structure of associations ap plicable to all the cities included in this analysis. 

### 33Draft

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- 218 September 2011 

### Table 6 - 49 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 from American Thoracic Society, Zanobetti and Schwartz ( 2008b )

. Samoli et al. ( 2009 ) also investigated the temporal pattern of mortality 

### 1 effects in response to short

- term exposure to O 3 in 21 European cities that were included 

### 2 in the APHEA2 project. Using a method similar to Zanobetti and Schwartz ( 2008b ) , the 

### 3 authors applied unconstrained distributed lag models with lags up to 21 days in each city 

### 4 during the summer months (i.e., Jun e through August) to examine the effect of O 3 on all



### 5 cause, 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 European multicity study ( Baccini et al., 2008 ) , which suggested that summer 

### 11 temperature effects 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 effects on respiratory mortality were extended for a period of two weeks. However, for 

### 14 all

- cause and cardiovascular mortality, the 21

- day distributed lag models yielded null or 

### 15 (non

- significant) negative estimates (Table 6

- 50 ). Figure 6

- 35 shows the distributed lag 

### 16 coefficients for all

- cause mortality, which exhibit a declining trend and ne gative 

### 17Draft

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- 219 September 2011 coefficients beyond 5

- day lags. The authors ’ interpretation of these results was that 

### 1

“ using single

- day exposures may have overestimated the effects on all

- cause and 

### 2 cardiovascular mortality, but underestimated the effects on respiratory mortality. ” Thus, 

### 3 the results in part suggest evidence of mortality displacement for all

- cause and 

### 4 cardiovascular mortality. 

### 5

Source: Reprinted with permission of American Thoracic Society ( Zanobetti and Schwartz, 2008b )

. The triangles represent the percent increase in all
- cause mortality for a 10 ppb increase in 8
- h max ozone concentrations at each lag while the shaded areas are the 95% point
- wise confidence intervals. 

### Figure 6 - 34 Estimated combined smooth distributed lag for 48 U.S. c ities during the summer months.Draft

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- 2 20 September 2011 

### Table 6 - 50 Estimated percent increase in cause - specific mortality (and 95% CIs) for a 10 - μg/m 3 

### increase in maximum 8 - h ozone during June - August, 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) Fixed effects Random effects % (95% CI) % (95% CI) Total mortality 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 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 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)

Source: Used with permission from 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 for 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, a reported 

### 8 percent excess risk for mortality for a 40 ppb increase in 1

- h max O 3 concentrations for 

### 9 lag 0

- 1, lag 1, and the distributed lag model (lag 0

- 2) was 2.70% (95% CI: 1.02, 4.40%), 

### 10 1.42% (95% CI: 0.08, 2.78%), and 3.0 2% (95% CI: 1.10, 4.89%), respectively. Thus, the 

### 11 observed associations appear to occur over a short time period, (i.e., a few days). 

### 12 Similarly, the Public Health and Air Pollution in Asia (PAPA) study ( Wong et al., 2010 ) 

### 13 also examined multiple lag days (i.e., lag 0, lag 0

- 1, and l ag 0

- 4), and although it did not 

### 14 specifically examine mortality displacement it does provide additional evidence 

### 15 regarding the timing of mortality effects proceeding O 3 exposure. In a combined analysis 

### 16 using data from all four cities examined (Bangkok, Hon g Kong, Shanghai, and Wuhan), 

### 17 excess risk estimates at lag 0

- 4 were larger than those at lag 0 or lag 0

- 1 in both fixed and 

### 18Draft

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- 221 September 2011 random effect models (results not presented quantitatively). The larger risk estimates at 

### 1 lag 0

- 4 can primarily be attributed to the strong associations observed in Bangkok and 

### 2 Shanghai. However, it is worth noting that Bangkok differs from the three Chinese cities 

### 3 included in this analysis in that it has a tropical climate and does not exhibit seasonal 

### 4 patterns of mortality. As a resu lt, Wong et al. ( 2010 ) examined the O 3 - mortality 

### 5 associations at lag 0

- 1 in only the three Chinese cities and found that risk estimates were 

### 6 slightly reduced from 2.26% (95% CI: 1.36, 3.16) in the 4 city analysis to 1.84% (0.77, 

### 7 2.86) in the 3 city analysis for a 30 ppb increa se in 8

- h max O 3 concentrations. Overall, 

### 8 the PAPA study further supports the observation of the APHENA study that associations 

### 9 between O 3 and mortality occur over a relatively short

- time period, but also indicates that 

### 10 it may be difficult to interpret O 3 - mortality associations across cities with different 

### 11 climates and mortality patterns. 

### 12 When comparing the studies that explicitly examined the potential for mortality 

### 13 displacement in the O 3 - mortality relationship, the results from Samoli et al. ( 2009 ) , which 

### 14 provide evidence that suggests morta lity displacement, are not consistent with those 

### 15 reported by Zanobetti and Schwartz ( 2008b ) . However, the shapes of the estimated 

### 16 smooth distributed lag associations are similar (Figure 6

- 34 and Figure 6

- 35). A closer 

### 17 examination of these figures shows that in the European data beyond a lag of 5 days the 

### 18 estimates remain negative whereas in the U.S. data the results remain near zero for the 

### 19 corresponding lags. These observed difference could be due the differences in the model 

### 20 specification between the 2 studies, specifically the use of: an unconstrained distributed 

### 21 lag model for apparent tempera ture up to 7 previous days ( Zanobetti and Schwartz, 

### 22 2008b ) versus a linear term for humidity and an unconstrained distributed lag model of 

### 23 temperature up to 3 previous days ( Samoli et al., 2009 ) ; and natural cubic splines with 

### 24 2 df per season ( Zanobetti and Schwartz, 2008b ) versus dummy variables per month per 

### 25 year to adjust for season ( Samoli et al., 2009 ) . It is important to note, that these 

### 26 differences in model specification may have also influenced the city

- to

- city variation in 

### 27 risk estimates observed in these two studies (i.e., homogenous estimates across cities in 

### 28 Zanobetti and Schwartz ( 2008b ) and heterogeneous estimates across cities in Samoli et 

### 29 al. ( 2009 ) . Overall, the evidence of mortality displacement remains unclear, but Samoli et 

### 30 al. ( 2009 ) , Zanobetti and Schwartz ( 2008b ) , and Katsouyanni et al. ( 2009 ) all suggest that 

### 31 the positive associations between O 3 and mortality are observed mainly in the first 

### 32 few days after exposure. 

### 33Draft

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- 222 September 2011 Source: Reprinted with permission of BMJ Group ( Samoli et al., 2009 )

. The triangles represent the percent increase in all
- cause mortality for a 10 μg/m 3 increase in 8
- h max ozone concentrations at each lag; the shaded area represents the 95% CIs. 

### Figure 6 - 35 Estimated combined smooth distributed lag in 21 European cities during the summer (June - August) months.
Adaptation Co ntrolled 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 mortality effects of O 3 . Zanobetti 

### 3 a nd 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 Schwa rtz ( 2008a ) examined O 3 - mortality associations by: season, month in the summer 

### 9 season (i.e., May through September), and age categories in the summer season (Table 6

- 

### 10 51 ). The estimated O 3 mortality ri sk estimate at lag 0 was found to be highest in the 

### 11 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% 

### 13Draft

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- 223 September 2011 [95% CI: 1.42, 2.48%]; 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 se ason. 

### 4

Table 6 - 51 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: Reprinted with per mission from BioMed Central Ltd. ( Zanobetti and Schwartz, 2008a )

. To further evalu ate 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 Au gust 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 estimates in August (0.84%) 

### 9 compared to July (1.96%) appears to supp ort the existence of an adaptive response. 

### 10 However, unlike an individual ’ s adaptive response to decrements in lung function from 

### 11 short

- term O 3 exposure, an examination of mortality prevents a direct observation of 

### 12 adaptation. Rather, for mortality the adap tation hypothesis is tested with a tacit 

### 13 assumption that, whatever the mechanism for O 3 - induced mortality, the risk of death 

### 14

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 presented in Table 6
- 47 from Zanobetti and Schwartz ( 2008a ) because the authors presented values for a 10 ppb increase in max 8
- h avg O 3 concentrations.Draft

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- 224 September 2011 from short

- term O 3 exposure is reduced over the course of the summer months through 

### 1 repeated exposures. This idea would translate t o a smaller population that would die from 

### 2 O 3 exposure towards the end of summer. This may complicate the interpretation of the 

### 3 distributed lag coefficients with long lag periods because the decreased coefficients may 

### 4 reflect diminished effects of the late summer, rather than diminished effects that are 

### 5 constant across the summer. These inter

- twined issues need to be investigated together in 

### 6 future research. 

### 7

Ozone - Mortality Concentration - Response Relationship and Threshold Analyses Several of the recent studies evaluated have applied a variety of statistical approaches to 

### 8 examine the shape of the O 3 - mortality C

- R relationship and whether a threshold exists. 

### 9 The approach used by Bell et al. ( 2006 ) consisted of applying four statistical models to 

### 10 the NMMAPS data, which included 98 U.S. communities for the period 1987

- 2000. 

### 11 These models included: a linear analysis (i.e., any change in O 3 concentration can be 

### 12 associated with mortality) (Model 1); a su bset analysis (i.e., examining O 3 - mortality 

### 13 relationship below a specific concentration, ranging from 5 to 60 ppb) (Model 2); a 

### 14 threshold analysis (i.e., assuming that an association between O 3 and mortality is 

### 15 observed above a specific concentration and n ot below it, using the threshold values set at 

### 16 an increment of 5 ppb between 0 to 60 ppb and evaluating a presence of a local minima in 

### 17 AICs computed at each increment) (Model 3); and nonlinear models using natural cubic 

### 18 splines with boundary knots placed at 0 and 80 ppb, and interior knots placed at 20 and 

### 19 40 ppb (Model 4). A two

- stage Bayesian hierarchical model was used to examine these 

### 20 models and O 3 - mortality risk estimates at the city

- level in the first stage analysis and 

### 21 aggregate estimates across cit ies in the 2nd stage analysis using the average of 0

- and 

### 22 1

- day lagged 24

- h avg O 3 concentrations. The results from all of these models suggest 

### 23 that if a threshold exists it does so well below the current O 3 NAAQS. When restricting 

### 24 the analysis to all days when the current 8

- h standard (i.e., 84 ppb daily 8

- h max) is met 

### 25 in each community, Bell et al. ( 2006 ) found there was still a 0.60% (95% PI: 0.30, 

### 26 0.90%) increase in mortality per 20 ppb increase in 24

- h avg O 3 concentrations at lag 0

- 1. 

### 27 Figure 6

- 36 shows the combined C

- R curve obtained using the nonlinear model (Model 

### 28 4). Although these results suggest the lack of threshold in the O 3

- mo rtality relationship, it 

### 29 is difficult to interpret such a curve because it do es not take into consideration the 

### 30 heterogeneity in O 3 - mortality risk estimates across cities. 

### 31Draft

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- 225 September 2011 Source: Bell et al. ( 2006 )

. 

### Figure 6 - 36 Estimated combined C - R curve for ozone and nonaccidental mortality using t he nonlinear (spline) model.
Using the same NMMAPS dataset as Bell et al. ( 2006 ) , Smith et al. ( 2009b ) furt her 

### 1 examined the O 3 - mortality C

- R relationship. Similar to Bell et al. ( 2006 ) , Smith et al. 

### 2 ( 2009b ) conduc t a subset analysis, but instead of restricting 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 O 3 concentrations above a value are so 

### 7 limited that the variability aro und the central estimate is increased. In the Smith et al. 

### 8 ( 2009b ) analysis this observation was initially observed at 45 ppb, with the largest 

### 9 variab ility at 60 ppb; however, unlike Bell et al. ( 2006 ) where 73% of days are excluded 

### 10 when subsetting the data to less than 20 ppb, the authors do not detail the number of days 

### 11 of data included in the subset analyses at higher concentrations. In addition to the subset 

### 12 analysis, Smith et al. ( 2009b ) examined the shape of the C

- R curve using a piecewise 

### 13 linear approa ch with cutpoints at 40 ppb, 60 ppb, and 80 ppb. Smith et al. ( 2009b ) found 

### 14 that the shape of the C

- R curve is similar to that reported by Bell et al. ( 2006 ) (Figure 

### 15 6

- 36), but argue that slopes of the β for each piece of the curve are highly variable with 

### 16Draft

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- 226 September 2011 the largest variation in the 60

- 80 ppb range. However, the larger variability around the β 

### 1 between 60

- 80 wo uld be expected due to the small number of days with O 3 

### 2 concentrations within that range in an all

- year analysis. This result is consistent with that 

### 3 observed by Bell et al. ( 2006 ) , which is presented in Figure 6

- 36. 

### 4 The APHENA project ( Katsouyanni et al., 2009 ) also analyzed the Canadian and 

### 5 European datasets (the U.S. data were analyzed for PM 10 only) for evidence of a 

### 6 threshold, using the threshold analysis method (Model 3) a pplied in Bell et al. ’ s ( 2006 ) 

### 7 study described above. There was no evidence of a threshold in the Canadian data (i.e., 

### 8 the pattern of AIC values for each increment of a potential threshold value varied across 

### 9 citie s, most of which showed no local minima). Likewise, the threshold analysis 

### 10 conducted using the European data also showed no evidence of a threshold. 

### 11 The PAPA study, did not examine whether a threshold exists in the O 3 - mortality C

- R 

### 12 relationship, but inste ad the shape of the C

- R curve individually for each city (Bangkok, 

### 13 Hong Kong, Shanghai, and Wuhan) ( Wong et al., 2010 ) . Using a natural spline smoother 

### 14 with 3df for the O 3 term, Wong et al. ( 2010 ) examined whether non

- linearity was present 

### 15 by testing the change in deviance between this smoothed, non

- line ar, model and an 

### 16 unsmoothed, linear, model with 1 df. For each of the cities, both across the full range of 

### 17 the O 3 distribution and specifically within the range of the 25th to 75th percentile of each 

### 18 city ’ s O 3 concentrations (i.e., a range of 9.7 ppb to 6 0.4 ppb across the cities) there was 

### 19 no evidence of a non

- linear relationship in the O 3 - mortality C

- R curve. It should be noted 

### 20 that the range of the 25 th to 75 th percentiles in all of the cities, except Wuhan, was lower 

### 21 than that observed in the U.S. using all

- year data where the range from the 25 th to 75 th 

### 22 percentiles is 30 ppb to 50 ppb (Table 3

- 6). 

### 23 Additional threshold analyses were conducted using NMMAPS data , by Xia and Tong 

### 24 ( 2006 ) and Stylianou and Nicolich ( 2009 ) . Both studies used a new statistic al approach 

### 25 developed by Xia and Tong ( 2006 ) to examine thresholds in the O 3 mortality C

- R 

### 26 relationship. The approach consisted of an extended GAM model, which accounted for 

### 27 the cumulative and nonlinear effects of air pollution using a weighted cu mulative sum for 

### 28 each pollutant, with the weights (non

- increasing further into the past) derived by a 

### 29 restricted minimization method. The authors did not use the term distributed lag model, 

### 30 but their model has the form of distributed lag model, except that it allows for nonlinear 

### 31 functional forms. Using NMMAPS data for 1987

- 1994 for 3 U.S. cities (Chicago, 

### 32 Pittsburgh, and El Paso), Xia and Tong ( 2006 ) found that the extent of cumulative effects 

### 33 of O 3 on mortality were relatively short. While the au thors also note that there was 

### 34 evidence of a threshold effect around 24

- h avg concentrations of 25 ppb, the threshold 

### 35 values estimated in the analysis were sometimes in the range where data density was low. 

### 36 Thus, this threshold analysis needs to be replica ted in a larger number of cities to confirm 

### 37Draft

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- 227 September 2011 this observation. It should be noted that the model used in this analysis did not include a 

### 1 smooth function of days to adjust for unmeasured temporal confounders, and instead 

### 2 adjusted for season using a temperatu re term. As a result, these results need to be viewed 

### 3 with caution because some potential temporal confounders (e.g., influenza) do not always 

### 4 follow seasonal patterns of temperature. 

### 5 Stylianou and Nicolich ( 2009 ) examined the existence of thresholds following an 

### 6 approach similar to Xia and Tong ( 2006 ) for all

- cause, cardiovascular, and respirato ry 

### 7 mortality using data from NMMAPS for nine major U.S. cities (i.e., Baltimore, Chicago, 

### 8 Dallas/Fort Worth, Los Angeles, Miami, New York, Philadelphia, Pittsburgh, and 

### 9 Seattle) for the years 1987

- 2000. The authors found that PM 10 and O 3 were the two 

### 10 impor tant predictors of mortality. Stylianou and Nicolich ( 2009 ) found that the estimated 

### 11 O 3 - mortality risks varied across the nine cities with the models exhibiting apparent 

### 12 thresholds, in the 10

- 45 ppb range for O 3 . However, given the city

- to

- city variation in 

### 13 risk estimates, combining the city

- specific estimates into an overall estimate complicates 

### 14 the i nterpretation of a threshold. Unlike the Xia and Tong ( 2006 ) analysis, Stylianou and 

### 15 Nicolich ( 2 009 ) included a smooth function of time to adjust for seasonal/temporal 

### 16 confounding, which could explain the difference in results between the two studies. 

### 17 In conclusion, the evaluation of the O 3 - mortality C

- R relationship did not find any 

### 18 evidence th at supports a threshold in the relationship between short

- term exposure to O 3 

### 19 and mortality within the range of O 3 concentrations observed in the U.S. Additionally, 

### 20 recent evidence suggests that the shape of the O 3 - mortality C

- R curve remains linear 

### 21 across the full range of O 3 concentrations. However, the studies evaluated demonstrated 

### 22 that the heterogeneity in the O 3 - mortality relationship across cities (or regions) 

### 23 complicates the interpretation of a combined C

- R curve and threshold analysis. Given the 

### 24 ef fect modifiers identified in the mortality analyses that are also expected to vary 

### 25 regionally (e.g., temperature, air conditioning prevalence), a national or combined 

### 26 analysis may not be appropriate to identify whether a threshold exists in the O 3 - mortalit y 

### 27 C

- R relationship. Overall, the studies evaluated support a linear O 3 - mortality C

- R 

### 28 relationship and continue to support the conclusions from the 2006 O 3 AQCD, which 

### 29 stated that “ if a population threshold level exists in O 3 health effects, it is likely ne ar the 

### 30 lower limit of ambient O 3 concentrations in the United States ” ( U.S. EPA, 2006b )

. 

### 31

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 mo rtality 

### 32 found consistent positive associations between short

- term O 3 exposure and 

### 33Draft

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- 228 September 2011 cardiovascular mortality, with less consistent evidence for associations with respiratory 

### 1 mortality. The majority of the evidence for associations between O 3 exposure and cau se 

### 2 specific mortality were from single

- city studies, which had small daily mortality counts 

### 3 and subsequently limited statistical power to detect associations. 

### 4 New multicity studies evaluated in this review build upon and confirm the associations 

### 5 between s hort

- term O 3 exposure and cause

- specific mortality identified in the 2006 O 3 

### 6 AQCD ( U.S. EPA, 2006b ) (Figure 6

- 37; Table 6

- 52 ). In APHENA, a multicontinent 

### 7 study that consisted of the NMMAPS, APHEA2 and Canadian multicity datasets, 

### 8 consis tent positive associations were reported for both cardiovascular and respiratory 

### 9 mortality in all

- year analyses when focusing on the natural spline model with 8 df/year 

### 10 (Section 6.6.2.1). The associations between O 3 exposure and cardiovascular and 

### 11 respiratory mortality in all

- year analyses were further supported by the multicity PAPA 

### 12 study ( Wong et al., 2010 ) . Cardiovascular mortality associations persisted in analyses 

### 13 restricted to the summer season with evidence for stronger respiratory mort ality 

### 14 associations compared to those observed in all

- year analyses (Figure 6

- 37; Table 6

- 52)

. 

### 15 Additional multicity studies from the U.S. ( Zanobetti and Schwartz, 2008b ) and Europe 

### 16 ( Stafoggia et al., 2010 ; Samoli et al., 2009 ) that conducted summer season analyses also 

### 17 found strong associations between O 3 exposure and cardiovascular and respiratory 

### 18 mortality. 

### 19 Of the studies evaluated, only the APHEN A study ( Katsouyanni et al., 2009 ) and an 

### 20 Italian multicity study ( Stafoggia et al., 2010 ) conducted an analysis of the potential for 

### 21 copollutant confounding of the O 3 cause - specific mortality relationship. When focusing 

### 22 on the natural spline model with 8 df/year and lag 1 results (as discussed in Section 

### 23 6.6.2.1), the APHENA study found that O 3 cause - specific mortality risk estimates were 

### 24 fairly robust to the inclusion of PM 10 in copollutant models in the European dataset with 

### 25 more variability in the U.S. and Canadian datasets (i.e., copollutant risk estimates 

### 26 increased and decreased for respira tory and cardiovascular mortality). In summer season 

### 27 analyses cardiovascular O 3 mortality risk estimates were robust in the European dataset 

### 28 and attenuated but remained positive in the U.S. datasets; whereas, respiratory O 3 

### 29 mortality risk estimates were at tenuated in the European dataset and robust in the U.S. 

### 30 dataset. The authors did not examine copollutant models during the summer season in the 

### 31 Canadian dataset (Figure 6

- 30; Table 6

- 4 9 ). Interpretation of these results requires 

### 32 caution; however, due to th e different PM sampling schedules employed in each of these 

### 33 study locations (i.e., primarily every

- 6th day in the U.S. and Canadian datasets and every



### 34 day in the European dataset). The results of the summer season analyses from the 

### 35 APHENA study ( Katsouyanni et al., 2009 ) are consistent with those from a study of 10 

### 36 Italian cities during the summer months ( Stafoggia et al., 2010 ) . Stafog gia et al. ( 2010 ) 

### 37 found that cardiovascular (14.3% [95% CI: 6.7, 22.4%]) and cerebrovascular (8.5% [95% 

### 38Draft

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- 229 September 2011 CI: 0.06, 16.3%]) mortality O 3 effect estimates were robust to the inclusion of PM 10 in 

### 1 copollutant models (14.3% [95% CI: 6.7, 23.1%] and 7.3% [95% CI:

- 1.2, 16.3], 

### 2 respectively), while respiratory mortality O 3 effects estimates (17.6% [95% CI: 1.8, 

### 3 35.5%]) were attenuated, but remained positive (9.2% [95% CI:

- 6.9, 28. 8%]). 

### 4

Effect estimates are for a 20 ppb increase in 24
- h avg; 30 in 8
- h max; and 40ppb increase in 1
- h max ozone concentrations. Red = cardiovascular; blue = respiratory; closed circles = all
- year analysis; and open circles = summer
- only analysis. An “ a ” represents studies from the 2006 ozone AQCD. A “ b ” represents risk estimates from APHENA
- Canada standardized to an approximate IQR of 5.1 ppb for a 1
- h max increase in ozone concentrations (Section 6.2.7.2). 

### Figure 6 - 37 Percent increase in cause - specific mortality. Study Bell et al. (2005; 74345)a Wong et al. (2010; 732535) Katsouyanni et al. (2009; 199899)

Gryparis et al. (2004; 57276)a Samoli et al. (2009; 195855) Zanobetti and Schwartz (2008; 101596) Stafoggia et al. (2010; 625034) Katsouyanni et al. (2009; 199899)

Bell et al. (2005; 74345)a Wong et al. (2010; 732535) Katsouyanni et al. (2009; 199899)

Gryparis et al. (2004; 57276)a Zanobetti and Schwartz (2008; 101596) Katsouyanni et al. (2009; 199899)
Samoli et al. (2009; 195855) Stafoggia et al. (2010; 625034) Katsouyanni et al. (2009; 199899) 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 % IncreaseDraft

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- 230 September 2011 

### Table 6 - 52 Corresponding effect estimates for Figure 6 - 37 Study Location Ages Lag Avg Time %Increase (95% CI) Cardiovascular

All - year 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 Gryparis et al. ( 2004 ) a 21 Europ ean 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 Bell et al. ( 2005 ) 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) Summer 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) 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 the case of respiratory 

### 3 mortality are strengthened, in the summer season. Although copollutant a nalyses of 

### 4 cause - specific mortality are limited, the APHENA study found that O 3 cause - specific 

### 5Draft

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- 231 September 2011 mortality risk estimates were fairly robust to the inclusion of PM 10 in copollutant models 

### 1 in the European dataset, which is supported by the results from Stafog gia et al. ( 2010 )

. 

### 2 Additionally, APHENA found that O 3 cause - specific mortality risk estimates were 

### 3 moderately to substantially sensitive (e.g., increased or attenuated) to inclusion of PM 10 

### 4 in the U.S. and Canadian datasets. However, the mostly every

- 6th

- day sampling schedule 

### 5 for PM 10 in the U.S. and Canadia n datasets greatly reduced their sample size and limits 

### 6 the interpretation of these results. 

### 7

6.6.3 Summary and Causal Determination The evaluation of new multicity studies that examined the association between short

- term 

### 8 O 3 exposure and mortality found evidence which supports the conclusions of the 2006 O 3 

### 9 AQCD. These new studies reported consistent positive associations between short

- term 

### 10 O 3 exposure and all

- cause (nonaccidental) mortality, with associations being stronger 

### 11 during the warm season, as well as add itional support for associations between O 3 

### 12 exposure and cardiovascular and respiratory mortality. 

### 13 New studies further examined potential confounders (e.g., copollutants and seasonality) 

### 14 of the O 3 - mortality relationship. Because the PM

- O 3 correlation vari es across regions, 

### 15 due to the difference in PM chemical constituents, interpretation of the combined effect 

### 16 of PM on the relationship between O 3 and mortality is not straightforward. Unlike 

### 17 previous studies that were limited to primarily examining the conf ounding effects of 

### 18 PM 10 , the new studies expanded their analyses to include multiple PM indices (e.g., PM 10 , 

### 19 PM 2.5 , and PM components). An examination of copollutant models found evidence that 

### 20 associations between O 3 and all

- cause mortality were robust to the inclusion of PM 10 or 

### 21 PM 2.5 ( Stafoggia et al., 2010 ; Katsouyanni et al., 2009 ; Bell et al. , 2007 ) , while other 

### 22 studies found evidence for a modest reduction (~20

- 30%) when examining PM 10 ( Smith 

### 23 et al., 2009b ) . Additional evidence suggests potential sensitivity (e.g., increases and 

### 24 attenuation) of O 3 mortality risk estimates to copollutants by age group or ca use - specific 

### 25 mortality (e.g., respiratory and cardiovascular) ( Stafoggia et al., 2010 ; Katsouyanni et al., 

### 26 2009 ) . An examination of PM components, specifically sulfate, found evidence for 

### 27 reductions in O 3 - mortality risk estimates in copollutant models ( Franklin and Schwartz, 

### 28 2008 ) . Overall, across studies, the potential impact of PM indices on O 3 - mortality risk 

### 29 estimates tended to be much smaller than the variation in O 3 - mortality risk estimates 

### 30 across cit ies suggesting that O 3 effects are independent of the relationship between PM 

### 31 and mortality. Although some studies suggest that O 3 - mortality risk estimates may be 

### 32 confounded by PM or its chemical components the interpretation of these results requires 

### 33 caut ion due to the limited PM datasets used as a result of the every

- 3rd

- and 6th

- day PM 

### 34 sampling schedule. When examining the potential for seasonal confounding of the 

### 35Draft

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- 232 September 2011 O 3 - mortality relationship it was observed that the extent of smoothing or the methods 

### 1 used for adjustment can influence O 3 risk estimates because of the opposing seasonal 

### 2 trends of O 3 and mortality when not instituting enough degrees of freedom to control for 

### 3 temporal/seasonal trends ( Katsouyanni et al., 2009 )

. 

### 4 The multicity studies evaluated in this review also examined the regional heterogeneity 

### 5 observed in O 3 - mortality risk estimates. These studies provide evidence which suggests 

### 6 generally higher O 3 - mortality risk estimates in northeastern U.S. cities with s ome regions 

### 7 showing no associations between O 3 exposure and mortality (e.g., Southwest, Urban 

### 8 Midwest) ( Smith et al., 2009b ; Bell and Dominici, 2008 ) . Mu lticity studies that examined 

### 9 individual

- and community

- level characteristics identified characteristics that may 

### 10 explain the observed regional heterogeneity in O 3 - mortality risk estimates as well as 

### 11 characteristics of populations potentially susceptible t o O 3 - related health effects. An 

### 12 examination of community

- level characteristics found an increase in the O 3 - mortality risk 

### 13 estimates in cities with higher unemployment, percentage of the population 

### 14 Black/African

- American, percentage of the working populatio n that uses public 

### 15 transportation, lower temperatures, and lower prevalence of central air conditioning 

### 16 ( Medina

- Ramón and Schwartz, 2 008 ) . Additionally, a potential interactive, or synergistic, 

### 17 effect on the O 3 - mortality relationship was observed when examining differences in the 

### 18 O 3 - mortality association across temperature levels ( Ren et al., 2008 ) . An examination of 

### 19 individual

- level characteristics found evidence that older age, female sex, Black race, 

### 20 having atrial fibrillation, SES indicators (i.e., educational attainment, income level, and 

### 21 employment status), and out

- of h ospital deaths, specifically in those individuals with 

### 22 diabetes, are modify O 3 - mortality associations ( Cakmak e t al., 2011 ; Stafoggia et al., 

### 23 2010 ; Medina

- Ramón and Schwartz, 2008 ) , and may increase susceptibility to O 3 - related 

### 24 mortality. Overall, additional research is warranted to further confirm whether these 

### 25 characteristics, individually or in combination, can explain the observed regional 

### 26 heterogeneity. 

### 27 Additional studies were evaluated that examined factors, such as multi

- day effects, 

### 28 mortality displacement, adaptation, and whether a threshold exists in the O 3 - mortality 

### 29 relationship, which may influence the shape of the O 3 - mortality C

- R curve. An 

### 30 examination of mul tiday effects in a U.S. and European multicity study found conflicting 

### 31 evidence for mortality displacement, but both studies suggest that the positive 

### 32 associations between O 3 and mortality are observed mainly in the first few days after 

### 33 exposure ( Samoli et al., 2009 ; Zanob etti and Schwartz, 2008b ) . A U.S. multicity study 

### 34 found evidence of an adaptive response to O 3 exposure, with the highest risk estimates 

### 35 earlier in the O 3 season (i.e., July) and diminished effects later (i.e., August) ( Zanobetti 

### 36 and Schwartz, 2008a ) . However, the evidence of adaptive effects has an implication for 

### 37 the interpretation of multi

- day effects, and requires further analysis. Analyses that 

### 38Draft

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- 233 September 2011 specifi cally focused on the O 3 - mortality C

- R relationship supported a linear O 3 - mortality 

### 1 relationship and found no evidence of a threshold within the range of O 3 concentrations 

### 2 in the U.S., but did observe evidence for potential differences in the C

- R relationsh ip 

### 3 across cities ( Katsouyanni et al., 2009 ; Stylianou and Nicolich, 2009 ; Bell et al., 2006 )

. 

### 4 Collectively, these studies support the conclusions of the 2006 O 3 AQCD that “ if a 

### 5 population threshold level exists in O 3 health effects, it is likely near the lower limit of 

### 6 ambient O 3 concentrations in the U.S. ” 

### 7 In conclusion, the new epidemiologic studies build upon and confirm the associations 

### 8 reported in the 2006 O 3 AQCD. Additionally, these new studies have provided additional 

### 9 information regarding key uncertainties previously identified including the potential 

### 10 confounding effects of copollutants and seasonal trend, individual

- and community

- level 

### 11 factors that may lead to increased risk of O 3 - induced mortality and the heterogeneity in 

### 12 O 3 - mortality risk estimates, and continued evidence of a linear no

- threshold C

- R 

### 13 relationship. Although some uncertainties still remain, the collective body of evidence is 

### 14 sufficient to conclude that there is likely to be a causal relationship between short 

### 15 term O 3 exposure and mortality. 

### 16



## 6.7 Overall Summary
The evidence reviewed in this chapter describes the recent findings regarding the health 

### 17 effects of short

- term exposure to ambient O 3 concentrations. Table 6

- 53 provides an 

### 18 overview of the causal determinations for each of the health categories evaluated. 

### 19

Table 6 - 53 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 Mortality Likely to be a causal relationshipDraft

– Do Not Cite or Quote 6
- 234 September 2011 

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. Adams, WC; Schelegle, ES. (1983). Ozone and high ventilation effects on pulmonary function and endurance performance. J Appl Physiol 55: 805
- 812. Adams, WC; Ollison, WM. (1997). Effects of prolonged simulated ambient ozone dosing patterns on human pulmonary function and symptomatology. In Presented at: 90th annual meeting of the Air & Waste Management Association; June; Toronto, Ontario, Canada Pittsburgh, PA: Air & Waste Management Association; paper no 97
- MP902. Adams, WC. (1998). Dose
- response effect of varied equivalent minute ventilation rates on pulmonary function responses during exposure to ozone. Washington, DC: American Petroleum Institute. Adams, WC. (2002). Comparison of chamber and face
- mask 6.6
- hour ex posures to ozone on pulmonary function and symptoms responses. Inhal Toxicol 14: 745
- 764. Adams, WC. (2003a). Comparison of chamber and face mask 6.6
- hour ex posure to 0.08 ppm ozone via square
wave and triangular profiles on pulmonary responses. Inhal Toxicol 15: 265
- 281. Adams, WC. (2003b). Relation of pulmonary responses induced by 66
- h exposures to 008 ppm ozone and 2
- h exposures to 030 ppm ozone via chamber and face
- mask inhalation. Inhal Toxicol 15: 745
- 759. Adams, WC. (2006a). Comparison of chamber 6.6
- h exposures to 0.04

– 0.08 PPM ozone via square
- wave and triangular profiles on pulmonary responses. Inhal Toxicol 18: 127
- 136. http://dx.doi.org/10.1080/089 58370500306107

. Adams, WC. (2006b). Human pulmonary responses with 30
- minute time intervals of exercise and rest when exposed for 8 hours to 0.12 ppm ozone v ia square
- wave and acute triangular profiles. Inhal Toxicol 18: 413
- 422. http://dx.doi.org/10.1080/08958370600563599

. Aibo, DI; Birmingham, NP; Lewandowski, R; Maddox, JF; Roth, RA; Ganey, PE; Wagner, JG; Harkema, JR. (2010). Acute exposure to ozone exacerbates acetaminophen
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