Association of air pollution with hospital outpatient visits in Beijing.

Data collected at a community-based hospital in Beijing, China, were analyzed in an assessment of the association of air pollution with daily outpatient visits. Total suspended particle (TSP) measurements were available for 210 d (mean, 388 micrograms/m3; maximum, 1,255 micrograms/m3), and sulfur dioxide (SO2) measurements were available for 2 d (mean, 119 micrograms/m3; maximum, 478 micrograms/m3). The average number of daily hospital outpatient visits was 1,386; approximately 8.5% of these visits were to the surgery department, 7.9% were to the pediatrics department, and 20.6% were to the internal medicine department. A large increase in nonsurgery outpatient visits was observed in association with increases in both SO2 and TSP in linear regression models, after adjusting for temperature, humidity, season, and day of the week. The estimated effects (in which the most polluted days were compared with the least polluted days) on nonsurgery outpatient visits were increases of 20% (SE = 5%) and 17% (SE = 4%) in association with increases in SO2 and TSP, respectively. In a department-specific analysis, the association was found to be 1.5- to 2.0-fold stronger for pediatrics and internal medicine visits than for other types of visits. The separate associations of SO2 and TSP with internal medicine visits remained statistically significant when both SO2 and TSP were considered simultaneously and when adjustment was made for surgery visits. SO2 and TSP were found to be significant, independent predictors of internal medicine visits in both winter and summer.(ABSTRACT TRUNCATED AT 250 WORDS)