Short-term exposure to ambient fine particulate matter constituents and myocardial infarction mortality.

Short-term ambient fine particulate matter (PM) exposure has been related to an increased risk of myocardial infarction (MI) death, but which PM constituents are associated with MI death and to what extent remain unclear. We aimed to explore the associations of short-term exposure to PM constituents with MI death and evaluate excess mortality. We conducted a time-stratified case-crossover study on 237,492 MI decedents in Jiangsu province, China during 2015-2021. Utilizing a validated PM constituents grid dataset at 1 km spatial resolution, we estimated black carbon (BC), organic carbon (OC), sulfate (SO), nitrate (NO), ammonium (NH), and chloride (Cl) exposure by extracting daily concentrations grounding on the home address of each subject. We employed conditional logistic regression models to evaluate the exposure-response relationship between PM constituents and MI death. Overall, per interquartile range (IQR) increase of BC (lag 06-day; IQR: 1.75 μg/m) and SO (lag 04-day; IQR: 5.06 μg/m) exposures were significantly associated with a 3.91% and 2.94% increase in odds of MI death, respectively, and no significant departure from linearity was identified in the exposure-response curves for BC and SO. If BC and SO exposures were reduced to theoretical minimal risk exposure concentration (0.89 μg/m and 1.51 μg/m), an estimate of 4.55% and 4.80% MI deaths would be avoided, respectively. We did not find robust associations of OC, NO, NH, and Cl exposures with MI death. Individuals aged ≥80 years were more vulnerable to PM constituent exposures in MI death (p for difference <0.05). In conclusion, short-term exposure to PM-bound BC and SO was significantly associated with increased odds of MI death and resulted in extensive excess mortality, notably in older adults. Our findings emphasized the necessity of reducing toxic PM constituent exposures to prevent deaths from MI and warranted further studies on the relative contribution of specific constituents.