Ambient air pollution and chronic respiratory morbidity in Delhi

The authors conducted a cross-sectional study among residents of Delhi to d etermine the role of ambient air pollution in chronic respiratory morbidity in Delhi. The authors selected a random, stratified sample (N = 4,171) of permanent residents who were 18+ y of age and who lived near 1 of the 9 per manent air quality monitoring stations in the city. Air-quality data for th e past 10 y were obtained; data were based on the differences in total susp ended particulates, and the study areas were categorized into lower- and hi gher-pollution zones. A standardized questionnaire was administered, clinic al examination was carried out, and spirometry followed. The authors assess ed chronic respiratory morbidity by (a) prevalence of chronic respiratory s ymptoms (i.e., chronic cough, phlegm, breathlessness, and wheezing) and air way diseases (i.e., chronic obstructive pulmonary disease/chronic bronchiti s and bronchial asthma); and (b) lung function results in asymptomatic nons moking subjects in the two pollution zones. A multiple logistic regression identified the determinants of chronic symptoms. Smoking, male sex, increas ing age, and lower socioeconomic status were strong independent risk factor s for occurrence of chronic respiratory symptoms. In the comparison of nons moking residents of lower- and higher-pollution zones-stratified according to socioeconomic levels and sex-chronic cough, chronic phlegm, and dyspnea (but not wheezing) were significantly more common in the higher-pollution z one in only some of the strata. Furthermore, prevalence rates of bronchial asthma, chronic obstructive pulmonary disease, and chronic bronchitis among residents in the two pollution zones were not significantly different. Non etheless, lung function of asymptomatic nonsmokers was consistently and sig nificantly better among both male and female residents of the lower-polluti on zone.