Air Pollution, Pollens, and Admissions for Chronic Respiratory Disease in King County, Washington

Abstract

We analyzed the association between various indices of air pollution, pollens, and hospital admissions for chronic respiratory disease in King County, WA, over the period 1987–1995. Both air pollution and tree pollens were independently associated with hospital admissions. In single-pollutant models, among the gases, we found the strongest association between carbon monoxide and hospitalization. The association with sulfur dioxide was weaker, and there was no evidence of an association with ozone. We also found association of hospital admissions with PM10, and a suggestion of an association with an index of light scattering measured by nephelometry. In two-pollutant models, the effect of carbon monoxide remained stable, whereas the effect of particulate matter, measured either as PM10 or by nephelometry, was attenuated and became unstable. We examined also the association between air pollution, pollens, and hospital admissions in three broad age groups, 0–19 yr, 20–64 yr, and 65 yr and older. Although tree pollens were associated with hospital admissions in each of these age groups, the association between air pollution and hospital admissions was seen only in the youngest age group.