Long term exposure to PM<sub>2.5</sub> chemical components associated with prevalence of cardiovascular diseases in China

Ambient fine particulate matter pollution (PM_2.5) has been widely associated with cardiovascular disease (CVD). However, less is known about the contribution of different chemical components of PM_2.5 to CVD using a nationally representative sample in China.

A nationally representative sample of older adults was recruited from 31 provinces, municipalities, or autonomous regions of China by the fourth national Urban and Rural Elderly Population Survey in 2015. We estimated the annual average concentrations of PM_2.5 and its five dust-free chemical components (black carbon [BC], organic matter [OM], sulphate [$ {\color[RGB]{39,137,177}{\robotoRefont\text{SO}_{\robotoRefont\text{4}}^{\robotoRefont\text{2-}} }}$], nitrate [${\color[RGB]{19,134,178} {\robotoRefont\text{N}\robotoRefont\text{O}}_{\robotoRefont\text 3}^{\robotoRefont\text -} }$], and ammonium [$ {\color[RGB]{19,134,178} {\robotoRefont\text{N}\robotoRefont\text{H}}_{\robotoRefont\text 4}^{\robotoRefont\text +} }$]) at geocoded residential addresses with the spatial resolution of 10��10 km using bilinear interpolation. Logistic regression models were constructed to estimate the associations between PM_2.5 chemical components and prevalence of self-reported CVD, and potential reducible fractions were further estimated using counterfactual analyses.

A total of 220,425 participants with a mean age of 69.73 years, 52.24% females, and 6.08% minor ethnicity were included in the study, of which 55,837 (25.3%) reported having CVD. An interquartile range (IQR) increment in annual PM_2.5 chemical components was associated with significantly elevated risk of CVD prevalence. The odds ratios were 1.254 (95% CI: 1.235-1.275, IQR: 7.11 ?g/m³) for $ \color[RGB]{19,134,178}{\robotoRefont\text{N}\robotoRefont\text{O}}_{\robotoRefont\text3}^{\robotoRefont\text-} $, 1.197 (95% CI: 1.178-1.216, IQR: 4.35 ?g/m³) for $ \color[RGB]{19,134,178}{\robotoRefont\text{N}\robotoRefont\text{H}}_{\robotoRefont\text 4}^{\robotoRefont\text +} $, 1.187 (95% CI: 1.173-1.202, IQR: 5.34 ?g/m³) for OM, 1.122 (95% CI: 1.107-1.137, IQR: 0.97 ?g/m³) for BC, and 1.106 (95% CI: 1.089-1.123, IQR: 4.67 ?g/m³) for $\color[RGB]{19,134,178} {\robotoRefont\text{S}\robotoRefont\text{O}}_{\robotoRefont\text 4}^{\robotoRefont\text 2-} $. The associations were significantly stronger in those older than 70 years.

Our study suggests that long-term exposure to PM_2.5 chemical components could increase the risk of CVD prevalence. Future air pollution guidelines target reducing specific PM_2.5 chemical components may help alleviate the burden of CVD.