# Presentation: 049869

## Ozone Health Effects:Findings of the First Draft Staff Paper 

- Susan Lyon Stone
- 2006 National Air Quality Conference
- February 6, 2006
- stone.susan@epa.gov

## Purpose of this First Draft Staff Paper

- To conclude whether consideration should be given to revising existing primary O3 NAAQS
- If so, what alternative standards should be considered for additional exposure and risk assessments
- The results of those assessments will inform staff recommendations on primary O3 NAAQS in next draft Staff Paper

## Ozone Irritates Airways

- Symptoms
- Cough
- Sore or scratchy throat
- Pain with deep breath
- Fatigue
- Rapid onset
- Similar symptoms - people with and without asthma

**Notes:**
Ozone is a powerful oxidizing agent that irritates the airways, producing 
Symptoms
Cough
Sore or scratchy throat
Pain when taking a deep breath – this may feel like a stitch in your side that doesn’t go away when you warm up – prevents you from taking a full deep breath
Fatigue – inability to carry on with normal energy levels
Symptoms come on quickly and are temporary, going away within a few hours
Even though some of the symptoms are like the symptoms of asthma, they can occur in people who do not have asthma

## Ozone Reduces Lung Function

- BASELINE

- 2HR

- 4HR

**FEV1, % CHANGE**

**-60**

**-40**

**-20**

**0**

**M-10**

**Notes:**
Another effect that comes on quickly is the reduction in lung function – this occurs when the smooth muscles that surround the airways contract
By lung function, we usually refer to the amount of air that can be exhaled after a full deep breath (FVC), and the speed at which the air can be exhaled (FEV1); ozone can reduce both of these measures of lung function
Controlled human exposure study: Vertical axis the percent reduction in FEV1 and horizontal axis duration of exposure; more subject in this study, for simplicity we showing the results of the subjects with the smallest, largest and intermediate responses
The first thing you notice magnitude of the reduction in lung function (about 50%)
Medium reduction in lung function (>10-20% reduction FEV1) perceptible wheeze or chest tightness
Large reduction in lung function (>20% FEV1) – obvious wheeze, marked chest tightness and breathing distress, brochodilator required to resolve symptoms
Incapacitating reduction in lung function (>>20% FEV1, or less than 50% of predicted lung function), severe breathing distress, possible emergency treatment required if persistent
The second thing you notice is that while one person is stopped in their tracks, another person had no change at all.   Typical of these studies – variability in responsiveness to ozone – brought these people back into the lab
One interesting thing is that we can’t predict who will be “unusually sensitive to ozone” – it’s not based on gender or any other known factor
People with asthma have the same range of responsiveness to asthma -- we say that they are more sensitive because they often have poorer lung function to begin with 

## M-1c

**M-1c**

**Notes:**
Ozone can cause inflammation
This is a schematic of an upper airway - BAL
Ciliated epithelial cells, underlying tissue, blood vessel and RBC (red), WBC (blue), white layer on top epithelial lining fluid
Ozone is a very reactive gas that primarily reacts with proteins and lipids in the ELF forming reactive oxygen species (e.g., lipid peroxides).  Only in places where the epithelial lining fluid is thin does ozone damage the epithelium directly  There is some evidence that taking antioxidants will mitigate the effects.  Once the damage occurs white blood cells start to influx to the area and inflammation occurs
We compare this inflammation to the inflammation you get on your skin with a sunburn
Swelling, redness
Doesn’t occur right away
Cells that line the airways die, are sloughed off and replaced new ones
In people with asthma this inflammation can lead to increased airway reactivity – real life 
Concern that repeated episodes of damage and healing may result in permanent structural changes in the lung “airway” resulting in reduced lung growth in children, and reduce quality of life in everyone

## Respiratory Morbidity

- Physiological bases of increased sensitivity of people with asthma
- Larger decreases lung function
- Increased occurrence and duration nonspecific airway responsiveness
- Increased airway responsiveness to allergens
- Increased inflammatory responses

## Respiratory Morbidity (cont.)

- Hospital admissions
- Emergency room visits
- School absences
- Increased symptoms and medication use in children

## Cardiovascular Morbidity -Very Limited Evidence

- Animal toxicology – hematological and thermoregulatory alterations
- Human exposure - impairment alveolar-oxygen transfer and ventilation-perfusion mismatch
- Epidemiology – myocardial infarction, changes in heart rate variability and arrhythmias

## Mortality

- Single city studies with statistically significant results have 98 and 99 percentile values below O3 NAAQS
- US multi-city time-series studies provide strong evidence of association between short-term O3 exposure and mortality
- Effects robust to confounding by copollutants

## Exposure Assessments

- Exposures of concern – 8-hour average exposures above 0.08 ppm
- Twelve urban areas across the US
- Two air quality scenarios – recent year (2004) and just meets 8-hour O3 NAAQS
- Active people, all children, active children

## Exposure Estimates

|                    Exposures of Concern (above 0.08 ppm, in thousands) |  |  |  |
| --- | --- | --- | --- |
|  | Active People | All Children | Active Children |
| Recent Year - 2004 | 1,598 | 618 | 376 |
| Just Meets 
Standard | 50 | 17 | 11 |

## Risk Assessments – Lung Function

- All exposures above background that resulted in:
- Moderate decrements or ≥ 15% reduction FEV1
- Large decrements or ≥ 20% reduction FEV1
- Same 12 urban areas and 2 air quality scenarios - recent air quality (2004) and just meets 8-hour O3 NAAQS
-  All children and active children

## Risk Estimates – Lung Function

| Air Quality
Scenario | Level of Lung 
Function Decrement | All Children - Ages 5-18 
(18.1 million total) |  |
| --- | --- | --- | --- |
|  |  | Persons 
(thousands and %
of population in
parentheses) | Person Days
(thousands) |
| 2004 | ≥ 15% | 1,728 (10%) | 15,410 |
| Just Meets | ≥ 15% | 1,156 (6%) | 7,640 |
| 2004 | ≥ 20% | 433    (2%) | 1,208 |
| Just Meets | ≥ 20% | 134    (1%) | 211 |

## Risk Assessment – Unscheduled Hospital Admissions

- New York City for recent year (2004) and just meets 8-hour O3 NAAQS
- Total respiratory illness – recent year
- 450 cases or 5.6 per 100,000 relevant population
- Asthma (subset of total) – recent year
- 380 cases, 4.8 per 100,000 relevant population
- Reduction in incidence for both total respiratory and asthma-related admissions about 19% from just meeting O3 NAAQS

## Risk Assessments - Mortality

- Estimated non-accidental and cardiorespiratory mortality
- Recent year (2004) and just meets 8-hour O3 NAAQS
- Single city and multi-city models
- Nonaccidental mortality
- Recent year – 0.4 to 7.3 per 100,000
- Just meets – 0.3 to 5.7 per 100,000
- Cardiorespiratory mortality
- Recent year – 0.4 to 1.3 per 100,000
- Just meets – 0.2 to 0.9 per 100,000

## Conclusions

- Averaging time
- 8-hour average protects against short-term and prolonged exposures
- Not appropriate at this time to conduct analyses of long-term exposures
- Form – nth-highest concentration
- Level
- Better understanding of physiological mechanisms of effects
- No apparent threshold for health effects
- Sufficient risks of various health endpoints remain after meeting current standard that additional analyses of alternative standards appropriate

## Odds Ratios (with 95% confidence intervals) for associations between O3 and respiratory symptoms, from warm season analyses, in order of increasing 98th and 99th percentile 8-hr O3 concentrations (in boxes)

- S = asthma symptoms
- MS = morning symptoms
- ES = evening symptoms
- MD = med use
- CT = chest tightness
- SB = shortness of breath
- C = cough
- W = wheeze

**Odds Ratios (with 95% confidence intervals) for associations between O****3**** and respiratory symptoms, from warm season analyses, in order of increasing 98****th**** and 99****th**** percentile 8-hr O****3**** concentrations (in boxes)**

- Delfino et al., 2003, San Diego CA

- Ross et al., 2002, East Moline IL

- Neas et al., 1995, Uniontown PA

- Mortimer et al., 2002, 8 US cities

- Gent et al., 2003, New England
- cities

- Ostro et al., 2001, Los Angeles CA

- S

- CT

- C

- S

- MD

- S

- W

- C

- SB

- MS

- ES

- MD

- 121
- 122

- 107
- 109

- 90.4
- ---

- 85.3
- 98

- 64.3
- 66

- 68.8
- 75

## Effect estimates (with 95% confidence intervals) for associations between O3 and hospitalization for respiratory diseases, in warm season analyses, in order of increasing 98th and 99th percentile 8-hr O3 concentrations (in boxes)

- LEGEND:
- R= respiratory
- A= asthma
- C= COPD
- RI= resp. infection
- P= pneumonia

- Schwartz et al., 1996 Cleveland

- Burnett et al.,  1997 Toronto

- Thurston et al., 1994 Toronto

- Thurston et al.,  1992 Buffalo

- Thurston et al., 1992 NYC

- Schwartz et al., 1996 Spokane

- Ito, 2003, Detroit

- Burnett et al., 1999 Toronto

- Burnett et al., 2001 Toronto

- Sheppard et al., 2003 Seattle

- Burnett et al., 1994 Toronto

- Delfino et al., 1994 Montreal

- 62
- 64

- 69
- 73.8

- 79
- 81.5

- 91
- 99

- 92
- 94

- 125.5
- 133

- 65
- 73

- 68.4
- 74.8

- 80
- 85

- A

- A

- R

- C

- C

- R

- R

- R

- R

- R

- RI

- P

- A

- A

- A

- R

- R

- 77.7
- 83.7

- 98th percentile values not available; are likely high-end concentrations based on data provided in study

## Additional Exposure and Risk Assessments

- Level of 0.06 ppm lowest air quality statistic credibly and significantly associated with increased respiratory morbidity effects such as symptoms and hospital admissions, and also daily mortality
- Additional assessments of alternative 8-hour average standards:
- 0.08 ppm, third-highest concentration
- 0.07 ppm, third- through fifth-highest concentrations
- 0.06 ppm, third- through fifth-highest concentrations

## Sensitive Groups

- Active people
- People with lung disease
- Children
- Older adults
- DOES NOT INCLUDE PEOPLE WITH HEART DISEASE