Air pollution and hospital admissions for chronic obstructive pulmonary disease in three metropolitan areas in the United States

I used generalized additive models to analyze the time series of daily admi ssions for chronic obstructive pulmonary disease (COPD) over the period 198 7-1995 in three major metropolitan areas, Cook County, Los Angeles County a nd Maricopa County, in the United States. In Cook and Maricopa counties I h ad admissions information only ibr the elderly (ages 65 yr and over). In Lo s Angeles County I had admissions information for all ages. In all three co unties I had monitoring information on PM10, CO, SO2, NO2, and O-3. In Los Angeles County, I had information on PM2.5 in addition, in Cook and Maricop a counties there was weak evidence of an association between the gaseous po llutants other than ozone and admissions. There was no evidence of an assoc iation with PM. In Cook and Los Angeles counties, in single-pollutant model s, ozone was associated with admissions during the period April-September b ur not in full-year analyses, in Los Angeles, the other gases were strongly associated with COPD admissions. PM was also associated with admissions in single-pollutant models. The coefficients for PM were greatly attenuated a nd became insignificant in joint analyses with any one of the gases (with t he exception of ozone). Analyses in three broad age ranges (0-19, 20-64, an d 65 yr and over) yielded similar results. The results indicate that the ga ses, other than ozone, were more strongly associated with COPD admissions t han PM and that there was considerable heterogeneity in the effects of indi vidual pollutants in different geographic areas of the country.