1. Development of California’s Ambient Air Quality Standards for Particulate Matter
Bart Ostro, Chief
Air Pollution Epidemiology Unit
Office of Environmental Health Hazard Assessment (OEHHA)
California EPA
Oakland, CA

2. California PM STANDARDS - 2002
PM10 – Reduced annual average from 30 to 20 g/m3 (USEPA = 50). 
– Retained 24-hour standard of 50 g/m3, not to be exceeded (USEPA = 150). 
PM – Added an annual average standard of 12 g/m3 (USEPA = 15).

3. Studies of Long-term Exposure and Life Expectancy
Several studies ( Harvard 6-Cities, American Cancer Society, Adventist Health Study) have examined the effects of long-term exposure to PM10, sulfates and/or PM2.5.
These ‘prospective cohort’ studies (gold standard) have followed study subjects for 7 to 16 years.
Analyses control for individual-level factors that may influence risk of mortality (e.g., age, gender, weight, tobacco and alcohol use, occupational exposure)

4. Harvard 6-cities Study (Dockery et al, 1993)
8,111 adults followed up to 16 years
Pollution monitors set up specifically for this study
Associations reported between both PM2.5 and PM10 and deaths from heart and lung disease
10 g/m3 associated with 8% increase in all-cause mortality

5. American Cancer Society Study
(Pope et al., 1995; 2002)
550,000 individuals in 151 cities followed for 7 and 16 years
Associations observed between PM2.5 and sulfate and both cardiopulmonary mortality and lung cancer
Results imply significant reduction in life expectancy. Between the most and least polluted cities (25 g/m3 PM2.5), the average decrease in life expectancy was about 1.5 years.
In addition, long-term exposure to PM10 or PM2.5 has been significantly associated with mortality due to various adverse health endpoints (like heart attacks, cardiopulmonary disease, and lung cancer).
Some of the strongest evidence is from one of the largest U.S. studies--the American Cancer Society or “ACS” study--with roughly half a million individuals in metropolitan areas around the U.S. Validated findings from several studies done on this group if individuals (or “cohort”) have provided strong evidence of death from cardiopulmonary disease and lung cancer. Also, the level of effect is significant as associated deaths from exposure reaching into the thousands per year.

6. Is the evidence consistent and coherent?
Long-term exposure studies supported by results from short-term exposure studies linking PM to:
Mortality
Cardiovascular and respiratory hospitalization and emergency room visits
Worsening of asthma
Bronchitis
Work loss, school absenteeism
Respiratory symptoms
Lung function decrements

7. Long-term Exposure Also Affects Morbidity in Children
Increased risk of bronchitis and chronic cough in children related to long-term exposure to PM10
PM exposure during pregnancy may be related to low birth weight, prematurity, and birth defects.
Over a 4-year (now 8) period, PM10, PM2.5, coarse particles, acid vapors, and NO2 were associated with reduced lung growth in L.A. Children’s Health Study

8. Rationale for Standard
Based on mortality – robust data.
Morbidity effects occur in same range of concentrations as mortality effects, thus protecting children and other susceptibles.
Focused on chronic exposures since higher effect estimates than those based on short-term averages.
Attaining annual standards will force down short-term averages/peaks.
Kept short term PM10 as a “backstop”.

9. PM10 Range of Long-Term Mean Concentrations
Observed in Epidemiologic Studies
Chronic Exposure Morbidity: Dockery et al., 1989; McConnell et al., 1999
(LA Children's Health Studies) 21 35
Chronic Exposure Mortality: Dockery et al., 1993 (Six-Cities Study) 18 28 46
Chronic Exposure Mortality: Pope et al., 1995 (ACS), PM10 Equivalent
CA Annual Standard Adopted June 2002 18 28 60
Time Series Mortality Studies 15 25 70 10 20 30 40 50 60 70 80
PM10 (mg/m3)
■ = Range of concentrations in a given study
 = Study mean concentration
 = Range of study mean concentrations among multiple studies o = Lower end of concentrations that may be more relevant to California

10. PM2.5 Range of Long-term Mean Concentrations
Observed In Epidemiologic Studies
Chronic Exposure Mortality: Dockery et al., 1993 (Six-Cities Study) 11 18 30
Chronic Exposure Mortality: Pope et al., 1995 (ACS) 9 20 35
Time Series Mortality Studies
CA Annual Standard Adopted June 2002 13 18 5 10 12 15 20 25 30 35 40
PM2.5 (mg/m3)
  ■ = Range of concentrations in a given study  = Study mean concentration
 = Range of study mean concentrations among multiple studies

11. 6,500 (95% C.I. = 3,200 – 9,800) premature deaths/year
Significant Benefits are Expected from Attaining the Annual Average Standards
Change to proposed annual average PM10 standard estimated to prevent about :
6,500 (95% C.I. = 3,200 – 9,800) premature deaths/year
thousands of hospitalizations for cardiopulmonary disease
389,000 lower respiratory symptoms among children aged 7 – 14
Calculations are based on data on population, current ambient concentrations, and exposure-response relationships derived from epidemiological studies.