Short-term effects of fine particulate matter constituents on myocardial infarction death

Existing evidence suggested that short-term exposure to fine particulate matter(PM_(2.5))may increase the risk of death from myocardial infarction(MI),while PM_(2.5) constituents responsible for this association has not been determined.We collected 12,927 MI deaths from 32 counties in southern China during 2011–2013.County-level exposures of ambient PM_(2.5) and its 5 constituents(i.e.,elemental carbon(EC),organic carbon(OC),sulfate(SO_(4)^(2-)),ammonium(NH_(4)^(+)),and nitrate(NO_(3)^(-)))were aggregated from gridded datasets predicted by Community Multiscale Air Quality Modeling System.We employed a space-time-stratified casecrossover design and conditional logistic regression models to quantify the association of MI mortality with short-term exposure to PM_(2.5) and its constituents across various lag days.Over the study period,the daily mean PM_(2.5) mass concentration was 77.8(standard deviation(SD)=72.7)μg/m^(3).We estimated an odds ratio of 1.038(95%confidence interval(CI):1.003-1.074),1.038(1.013-1.063)and 1.057(1.023-1.097)for MI mortality associated with per interquartile range(IQR)increase in the 3-day moving-average exposure to PM_(2.5)(IQR=76.3μg/m 3),EC(4.1μg/m^(3))and OC(9.1μg/m^(3)),respectively.We did not identify significant association between MI death and exposure to water-soluble ions(SO_(4)^(2-),NH_(4)^(+)and NO_(3)^(-)).Likelihood ratio tests supported no evident violations of linear assumptions for constituents-MI associations.Subgroup analyses showed stronger associations between MI death and EC/OC exposure in the elderly,males and cold months.Short-term exposure to PM_(2.5) constituents,particularly those carbonaceous aerosols,was associated with increased risks of MI mortality.