Association Between PM10 and Respiratory Hospital Admissions in Different Seasons in Heavily Polluted Lanzhou City

Exposure-response relationship between particulate matter less than 10 μm in diameter (PM10) and human health in different seasons from 2001 to 2005 was examined based on hospital admissions data of respiratory system diseases from four major hospitals in Lanzhou, China. To quantify associations of respiratory system diseases with multiple air pollutants and meteorological conditions, a semiparametric generalized additive model was used in the authors’ study by implementing daily ambient sulfur dioxide, nitrogen dioxide, and PM10 data collected from the Lanzhou Environmental Monitoring Station and daily meteorological data from Lanzhou Meteorological Bureau. Results showed that daily averaged PM10 increased per interquartile range the hospital admissions number of respiratory diseases by 3.3% in spring, 1.4% in summer, 3.6% in autumn, and 4.0% in winter from a singlepollutant model, or 3.1%, 1.4%, 3.0%, and 4.0% from a multi-pollutant model, respectively. The effect of PM10 on respiratory hospital admissions was lowest in summer and highest in winter. The relative risks of PM10 on female or the elderly (≥65 yrs.) were higher, showing a stronger association of PM10 with respiratory diseases in female and elderly groups than in males and people younger than 65.