The Role of Ambient Air Pollution in the Occurrence of Emphysema

Emphysema is the most common cause of death from respiratory disease in the United States. Emphysema is most common among people aged 50 and older. Those with a genetic predisposition to emphysema may experience the onset as early as their thirties or forties. Men are more likely than women to develop emphysema, but female cases are increasing as the number of female smokers rises. In the past few years, etiological and pathogenic research has been carried out in an attempt to determine the reason for an increase in deaths and other health problems associated with air pollution, and there have been significant improvements in our knowledge concerning the effects of air pollution on respiratory disease. Although chronic obstructive pulmonary disease (COPD) mortality has been studied extensively in the past 20 years, to our knowledge, the relationship between long-term ambient air pollution (especially PM10 and ozone) and incidence of emphysema has not been reported. This dissertation evaluates associations between incidence of emphysema and long-term ambient concentrations of PM10 and ozone using data from the Adventist Health and Smog (AHSMOG) study. A cohort of 6,338 non-Hispanic, white California adults, ages 27-95, was followed from 1977 to 2000 for various chronic disease outcomes including self-reported physician diagnosed emphysema. Monthly ambient air pollution data were interpolated to zip code centroids according to home and work location histories and averaged over time. Logistic regression analyses, using the generalized model (PROC GENMOD in SAS statistical software) were used to evaluate the association between mean concentration of PM10, and ozone and period incidence of emphysema adjusting for age, sex, education and pack years of past cigarette smoking. The results of this study indicate that each 10 ug/m3 increase in mean concentration of PM10 and each 10 ppb increase in mean concentration of ozone were associated with increased number of new emphysema cases with OR = 1.23 (95% Cl: 1.06-1.43) and OR =1.48 (95% Cl: 1.06-2.07), respectively, after controlling for pack-years of past cigarette smoking, age and educational level. In addition, we observed significant associations between incidence of emphysema and each 40 day increment of ambient PM10 levels in excess of 40, 60, 80 and 100 ug/m3 and each 10 days average annual increment of ozone in excess of 100, 120 and 150 ppb. Our findings suggest that chronic exposure to ambient air pollution is associated with development of emphysema in adults