Hourly differences in air pollution and risk of respiratory disease in the elderly: a time-stratified case-crossover study

摘要

BackgroundEpidemiological studies have shown adverse effects of short-term exposure to air pollution on respiratory disease outcomes; however, few studies examined this association on an hourly time scale. We evaluated the associations between hourly changes in air pollution and the risk of respiratory disease in the elderly, using the time of the emergency call as the disease onset for each case.