Black Carbon (PM2.5 Component) and Acute Myocardial Infarction Risk: A Time-stratified Case-crossover Study in Japan

Abstract

Particulate matter with an aerodynamic diameter of ≤ 2.5 µm (PM2.5) is a heterogeneous mixture, but specific substances that affect cardiovascular events remain unknown. We aimed to examine the association of short-term exposure to PM2.5 and its components with hospital admissions for acute myocardial infarction (AMI). The concentrations of total PM2.5 and its individual components were continuously measured using aerosol speciation analyzers. From a national-scale administrative database collected from 828 facilities in 47 prefectures across Japan from April 2017 to December 2019, we extracted AMI data for seven prefectures where these aerosol analyzers were installed. The primary outcome was the relationship of PM2.5 and its components with AMI hospitalization. A time-stratified case-crossover analysis was conducted, and the approximate risk of AMI by pollutant concentrations was estimated using a conditional logistic regression model. A total of 44,232 patients with AMI were examined. The estimated effects of an increase in the interquartile range of total PM2.5 on AMI-associated hospitalization were significant and comparable to those of optically measured black carbon concentrations. Short-term exposure to PM2.5 was associated with an increased AMI incidence. Reduction in black carbon concentration may decrease the risk of future air quality-related AMI.