RESUMO
BACKGROUND: The objective of this study was to evaluate the impact of air particulate matter 2.5 (PM2.5) on the daily number of patients' visits to the Department of Respiratory Diseases in a local general hospital. METHODS: The number of patients in outpatient department of respiratory diseases (ODRD) in a general hospital of Jinan, China, the air quality and meteorological data were collected for 1 year. By controlling the confounding factors such as "day of the week" effects and the meteorological factors, the generalized additive Poisson regression analysis was conducted to evaluate the impact of PM2.5 on the number of patients' visits to the ODRD. RESULTS: Within two consecutive days, if the cumulative PM2.5 was less than 200 µg/m(3), the daily number of patients in the ODRD did not increase significantly; however, it increased dramatically when the concentration of PM2.5 particles reached the range between 200 and 400 µg/m(3). CONCLUSION: There is a non-linear relationship between the concentration of atmospheric PM2.5 particles and the daily number of patients in the ODRD.