Potential causal links between long-term ambient particulate matter exposure and cardiovascular mortality: New evidence from a large community-based cohort in South China.

Background: Cardiovascular disease (CVD) mortality is associated with long-term particulate matter (PM) exposure. However, evidence from large, highly-exposed population cohort and observational-data-based causal inference approaches remains limited.

Aims: We examined the potential causal links between PM exposure and the CVD mortality in South China.

Methods: 580,757 participants were recruited during 2009-2015 and followed up through 2020. Satellite-based annual concentrations of PM, PM, and PM (i.e., PM - PM) at 1 km spatial resolution were estimated and assigned to each participant. Marginal structural Cox models with time-varying covariates, adjusted using inverse probability weighting, were developed to evaluate the association between prolonged PM exposure and CVD mortality.

Results: For overall CVD mortality, the hazard ratios and 95% confidence interval for each 1 μg/m increase in the annual average concentration of PM, PM, and PM were 1.033 (1.028-1.037), 1.028 (1.024-1.032), and 1.022 (1.012-1.033), respectively. All three PMs were linked to a higher mortality risk for myocardial infarction and ischemic heart disease (IHD). The mortality risk of chronic IHD and hypertension was linked to PM and PM. Significant association between PM and other heart disease mortality was also observed. The older, women, less-educated participants, or inactive participants exhibited particularly higher susceptibility. Participants who were generally exposed to PM concentrations below 70 μg/m were more vulnerable to PM-, PM- and PM-CVD mortality risks.

Conclusion: This large cohort study provides evidence for the potential causal links between increased CVD mortality and ambient PM exposure, as well as socio-demographics linked to the highest vulnerability.