Objective To investigate the effect of ambient PM2.5 on hospital visits due to respiratory diseases in Hangzhou.
Methods The meteorological data (including average daily temperature, relative humidity, air pressure, and wind speed), the air pollutant data (including average concentrations of PM10, PM2.5, NO2, CO, SO2, and O3) recorded by ten national monitoring stations, and the data of hospital visits due to respiratory diseases (including chronic obstructive pulmonary disease, asthma, pneumonia, bronchitis, allergic rhinitis, and other acute upper respiratory tract infections) were collected from 2013 to 2014 from nine tertiary grade-A hospitals in Hangzhou urban areas. Time-series analysis with generalized additive model (GAM) was applied to reveal the association between the average daily concentration of PM2.5 and the hospital visits for respiratory diseases.
Results The average daily concentrations of SO2, NO2, O3, and CO were all qualified for the grade Ⅰ standard of GB 3095-2012 Environmental Air Quality Criterion, while the concentration of PM2.5 (61.51 μg/m3) and PM10 (92.33 μg/m3) were exceeding the national grade Ⅰ standard but within the grade Ⅱ standard. The effect of exposure to PM2.5 on visits for respiratory diseases was strongest on lag day 10. The single-pollutant model suggested that the hospital visits from whole population, children (≤ 12 years), and the elderly (≥ 65 years) increased 0.226% (95% CI:0.159%-0.293%), 0.289% (95% CI:0.198%-0.380%), and 0.266% (95% CI:0.168%-0.375%), respectively, on lag day 10 for per 10μg/m3 increase of PM2.5. In the multi-pollutant model, a much stronger health effect of PM2.5 was observed:the hospital visits from whole population, children (≤ 12 years), and the elderly (≥ 65 years) increased 0.340% (95% CI:0.221%-0.459%), 0.365% (95% CI:0.230%-0.500%), and 0.374% (95% CI:0.235%-0.513%), respectively, on lag day 10 for per 10μg/m3 increase of PM2.5.
Conclusion PM2.5 pollution displays a positive association with hospital visits for respiratory diseases in Hangzhou with certain lagged effect. Children and the elderly are more sensitive to PM2.5 pollution than the other groups.
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