Association between PM2.5 and its chemical components exposure and heart disease risk: a longitudinal study from China

Air pollution, particularly fine particulate matter (PM 2.5 ) and its chemical components, poses a significant threat to public health. However, the association between these pollutants and heart disease risk, have not been thoroughly investigated, especially regarding differential effects across various populations and regions. we analysed 8,172 participants from 123 cities across China. Cox proportional hazards regression models were used to assess the association between PM 2.5 and its major chemical components (sulfate [SO₄²⁻], nitrate [NO₃⁻], ammonium [NH₄⁺], organic matter [OM], and black carbon [BC]) with heart disease risk. We constructed three progressively adjusted models, employed Weighted Quantile Sum regression to evaluate the composite effects of pollutant mixtures, used restricted cubic splines to explore dose-response relationships, and calculated Population Attributable Fraction. Additionally, stratified analyses were conducted to explore effect modification by age, gender, body mass index (BMI), residence, geographic region, smoking status, and drinking status. The study found significant associations between PM 2.5 and all its major chemical components with heart disease risk ( p < 0.001). In the fully adjusted model (Model 3, adjusted for age, gender, body mass index, marital status, retirement status, residence, geographic region, education level, sleep duration, smoking, and drinking), each 1 µg/m³ increase in PM 2.5 concentration was associated with a 2.7% increase in heart disease risk (hazard ratio [HR] = 1.027, 95% confidence interval [CI]: 1.022–1.032). Among the chemical components, BC showed the largest estimate per 1 µg/m³ increase associated with a 38.1% increase in risk (HR = 1.381, 95% CI: 1.266–1.506). All pollutants exhibited non-linear dose-response relationships with heart disease risk (p for nonlinear < 0.001). Geographic region and BMI were important effect modifiers, with southern residents and overweight individuals showing increased stronger associations to air pollution-related heart disease risks. The PAF of heart disease due to PM 2.5 was 2.63%. PM 2.5 and its chemical components are significantly associated with heart disease risk, with notable differences in impact magnitude across components. BC showed the strongest association with heart disease risk. Southern residents and overweight individuals showed increased stronger associations to air pollution-related heart disease risks.