Objective: Using case-crossover design to explore the association between ambient air pollution and the hospital emergency room visits for respiratory diseases (International Classification of Diseases, tenth vision ICD-10: J00-J99) in Beijing, China.
Methods: Data regarding the daily hospital emergency room visits of the respiratory diseases (ICD-10: J00-J99) were obtained in 2004.01.01 - 2005.12.31, from the Peking University Third Hospital and data on relevant air pollution and meteorological factors from the local municipal environmental monitoring center and meteorology bureau of Beijing, respectively. Time-stratified case-crossover technique was used to evaluate their relationships. Results from the bi-directional control sampling approach were compared with unidirectional approach.
Results: Using a unidirectional control sampling approach, the results obtained from a conditional logistic regression model (multi-pollutant model) after adjusting for meteorological variables, showed that the ORs of the hospital emergency room visits for the respiratory diseases associated with each 10 µg/m(3) increment of PM(10), SO(2), NO(2) were 1.010 (95%CI: 1.005 - 1.014), 1.010 (95%CI: 1.001 - 1.018), 0.996 (95%CI: 0.983 - 1.009) respectively. In the bi-directional control sampling approach, the ORs were 1.002 (95%CI: 0.998 - 1.005), 1.011 (95%CI: 1.003 - 1.018), 1.012 (95%CI: 1.001 - 1.022).
Conclusion: Results from this study provided evidence that higher levels of ambient air pollutants increased the risk of hospital emergency room visits for respiratory diseases.