Relationship between visits to emergency departments for asthma and ozone exposure in greater Seattle, Washington

Background: Air pollution is known to affect asthma symptoms in controlled and epidemiologic studies. Objective: To determine whether ozone exposure in Seattle is associated with increased use of hospital emergency departments. Methods: Hospital data on daily asthma cases for all ages were obtained for 1998 through 2002. Ozone and fine particulate matter (<= 2.5 mu m in diameter) (PM2.5) data were obtained from local air agencies. Poisson regression models were used to assess the association between asthma visits to emergency departments and air pollutants. Maximum daily 1- and 8-hour average ozone concentrations and the daily PM2.5 concentration were used. Results: We observed associations between both ozone metrics and emergency department visits in children. For the maximum daily 1- and 8-hour average ozone concentrations, the relative risks (RRs) were 1.08 (95% confidence interval [CI], 1.00-1 18) and 1.11 (95% CI, 1.02-1.21), respectively, at 3 clays' lag. Weaker but significant associations were also observed for adults For the maximum daily 1-hour average ozone concentration. the RR was 1.06 (95% CI, 1.01-1.11) at 4 days' lag, and for the maximum daily 8-hour average ozone concentration, the RR was 1.06 (95% CI, 1.01-1.12) at 2 days' lag and 1.08 (95% CI, 1.02-1 14) at 4 days' lag Conclusion: Ozone exposure exacerbates asthma in people in the Seattle area, especially in children. Ann Allergy Asthma Immunol. 2009;103;474-479.