Reductions in acute myocardial infarction burden linked to short-term PM2.5 exposure: Evidence from the Chinese CCA Registry

Background PM2.5 (fine particulate matter with aerodynamic diameter ≤ 2.5μm) concentrations have substantially declined in the past decade across China, but temporal changes of morbidity burden of acute myocardial infarction (AMI) attributable to short-term exposures to PM2.5 and its various chemical constituents, including black carbon (BC), organic matter (OM), ammonium (<tex-math id="M1">NH₄⁺</tex-math>), nitrate (<tex-math id="M2">NO₃⁻</tex-math>) and sulfate (<tex-math id="M3">SO₄²⁻</tex-math>) in China remain unknown. Methods A time-stratified case-crossover design was applied in 785,052 AMI cases across China during 2017-2020. We utilized conditional logistic regression models to estimate the excess risks (ERs) and attributable fractions (AFs) from AMI onset attributable to short-term exposures (lag01 day) to PM2.5 and constituents, and used linear regression models to estimate temporal changes of AFs of AMI morbidity. Results The annual average reductions in concentrations of PM2.5 mass, BC, OM, <tex-math id="M4">NH₄⁺</tex-math>, <tex-math id="M5">NO₃⁻</tex-math> and <tex-math id="M6">SO₄²⁻</tex-math> during 2017-2020 were respectively 3.05μg/m³/year, 0.15μg/m³/year, 0.70μg/m³/year, 0.31μg/m³/year, 0.44μg/m³/year, and 0.51μg/m³/year. Correspondingly, the annual average reductions in AFs were recorded as -0.53% (95%CI: -0.92%, -0.15%), -0.29% (95%CI: -0.43%, -0.15%), -0.45% (95%CI: -0.78%, -0.12%), -0.33% (95%CI: -0.51%, -0.16%), -0.36% (95%CI: -0.59%, -0.13%), and -0.48% (95%CI: -0.86%, -0.10%), respectively. The temporal reduction of PM2.5-attributed and chemical constituents-attributed AFs were greater in females, people aged ≥65 years, non-ST-segment-elevation myocardial infarction (NSTEMI) cases, and people resided in Southern China. Conclusions As the concentration of PM2.5 mass and chemical constituents decreased over the years, the decline was observed in the morbidity burden of AMI attributable to PM2.5 and its constituents across China from 2017 to 2020.