Seasonal variation in association between air pollution and ischemic heart disease mortality in Wuhan,China

Objective To explore the association between short-term exposure to ambient air pollution and ischemic heart disease(IHD)mortality as well as seasonal variation of the association in Wuhan city,China.Methods Data on daily IHD mortality for the period of 2002 through 2010 was obtained from Jiang'an District Center for Disease Control and Prevention,Wuhan and the data on concentration of relevant air pollution and meteorological factors from local municipal environmental monitoring center and meteorology bureau of Wuhan,respectively.Quasi-Poisson regression of generalized additive model was applied to evaluate the association between air pollution and IHD mortality,using both all-season and season-specific models.Results Ambient pollution level and IHD deaths reached highest in winter among the four seasons.Annual average concentrations of particulate matter less than 10 μm in aerodynamic diameter(PM₁₀),sulfur dioxide(SO₂),and nitrogen dioxide(NO₂)in winter were 143.8±70.9 μg/m³,71.0±42.4 μg/m³,and 66.5±25.6 μg/m³,respectively,and 1.64 IHD deaths per day occurred in winter.In all-season model,a 10 μg/m³ increase in previous day(lag 1)for PM₁₀ was associated with 0.86%(95%confidence interval95%CI:0.22%-1.51%)excess risk in IHD mortality and no statistically significant association between gaseous pollutants(SO₂,NO₂)and IHD mortality was found.The season-specific model showed that ambient pollutants were consistently associated with increased IHD mortality only in winter(from 1st of November to 28th of February)and a 10 μg/m³ increase in previous day(lag1)ambient pollutants was associated with 1.40%(95%CI:0.58%-2.23%)excess risk in IHD mortality for PM₁₀,1.65%(95%CI:0.28%-3.05%)excess risk for SO₂,and 3.05%(95%CI:0.92%-5.23%)excess risk for NO₂,respectively.Conclusion In Wuhan city,short-term exposure to air pollution was associated with increased IHD death and a seasonal pattern with an obvious peak in winter was consistently found in the acute effects of both PM₁₀ and gaseous pollutants(SO₂,NO₂)on IHD mortality.