Particulate air pollution and chronic respiratory disease.

Chronic exposure to particulates has been associated with increased rates of bronchitis and other respiratory ailments, with loss of lung function, and with increased risk of lung cancer. Despite these findings, debate continues about the adverse health effects of exposure to airborne particles at concentrations often seen in urban areas. This issue was examined by looking at reported rates of chronic respiratory illness by standardized questionnaire across 53 urban areas in the United States. Diagnosis of respiratory illness by an examining physician in the First National Health and Nutrition Examination Survey was also considered as an outcome. After controlling for age, race, sex, and cigarette smoking, annual average total suspended particulate concentrations (TSP) were associated with increased risk of chronic bronchitis (odds ratio (OR) = 1.07, 95% confidence interval (CI) 1.02-1.12) and of a respiratory diagnosis by the examining physician (OR = 1.06, 95% CI = 1.02-1.11). The odds ratios are for a 10 micrograms/m3 increase in TSP. When the analysis was restricted to never smokers, the associations remained, with a slight increase in the relative odds associated with airborne particles. Plots of the relative odds by quartiles of TSP exposure, adjusting for covariates, showed dose-dependent increases in risk with increasing exposure. The risk appeared to continue to concentrations below the ambient air quality standard. Given the other recent findings of both acute and chronic effects of particulate pollution, these associations are likely causal.