Association between short-term exposure to fine particulate matter constituents and sudden cardiac death: A case-crossover study in Fujian Province, China

Fine particulate matter (PM_2.5) is a known trigger for acute cardiac events, but the specific constituents driving the risk for sudden cardiac death (SCD) remain unclear. This study aimed to identify these key constituents.

This time-stratified case-crossover study included 19,501 SCD cases in Fujian Province, China (2013-2023). Daily exposures to PM_2.5 and its major constituents were estimated using high-resolution satellite-derived data. A comprehensive strategy including two-pollutant, constituent-residual, and source apportionment models was employed to address multicollinearity among pollutants. Exposure-response and stratified analyses were also performed.

Short-term exposure to PM_2.5 and its constituents was associated with an increased risk of SCD, especially for sulfate (SO₄^2-) (odds ratio [OR] = 1.05, 95 % confidence interval [CI]: 1.03-1.08). Multicollinearity analyses showed that only the SO₄^2- association remained robust, statistically attenuating effects of other constituents and of total PM_2.5 mass. Source apportionment linked SCD risk primarily to the secondary inorganic aerosol source, for which SO₄^2- is a key marker. Exposure-response curves for inorganic ions were non-linear. While subgroup differences were not statistically significant, higher risks were observed for males, older adults, individuals with lower educational levels, and during cold months. Associations for most pollutants, particularly for SO₄^2-, appeared stronger in 2021-2023 despite declining average concentrations.

Short-term exposure to PM_2.5 constituents is a significant risk factor for SCD. SO₄^2- is proved to be a primary driver of this association. The findings indicate that the acute cardiac toxicity of PM_2.5 is determined more by its specific chemical composition than by total particle mass.