Air quality and outpatient visits for asthma in adults during the 2008 Summer Olympic Games in Beijing.

To fulfill its commitment to a successful 2008 Olympic and Paralympic Games, the Chinese government made unprecedented efforts to improve the air quality in Beijing. We report findings on air quality and outpatient visits for asthma among adults in Beijing during the 2008 Summer Olympic Games. Three study periods were defined: summer baseline (June 1-June 30: before any air pollution controls), pre-Olympics (July 1-August 7: transportation restrictions in effect), and Olympics (August 8-September 20: further restrictions on industrial emissions). Daily data on outpatient asthma visits were obtained from the asthma registry of Beijing Chaoyang Hospital. We used time-series Poisson regression models to estimate the relative risk (RR) for asthma visits associated with pollution levels. The average numbers of outpatient visit for asthma were 12.5 per day at baseline and 7.3 per day during the Olympics. Compared with baseline, the Games were associated with a significant reduction in asthma visits (RR 0.54, 95%CI: 0.39-0.75). Our analysis showed that even in a heavily-polluted city, decreased concentrations of small particles were associated with some reduction in asthma visits in adults.