The role of long-term PM2.5 peaks in cardiovascular risk: an AIRCARD substudy.

Background: Cardiovascular disease is a leading cause of mortality globally, with air pollution, particularly fine particulate matter (PM_2.5), recognized as a significant risk factor. While long-term accumulated exposure to PM_2.5 has been extensively studied, the impact of PM_2.5 peaks on cardiovascular events remains unexplored.

Methods: This prospective cohort study analyzed data from 26,723 male participants aged 65 to 74 years from the Danish DANCAVAS and VIVA screening trials. We assessed the association between long-term cumulated repeated PM_2.5 peak exposure and major adverse cardiovascular events (MACE), including non-fatal acute myocardial infarction, non-fatal stroke, cardiovascular mortality, and revascularization procedures, using Cox proportional hazards models. PM_2.5 peak exposure was treated as a time-varying variable, and models were adjusted for potential confounders, including individual-level demographic, clinical, and socioeconomic factors. PM_2.5 peaks were defined as monthly average concentrations exceeding the long-term mean by more than two standard deviations.

Results: The fully adjusted model showed no significant elevation in the risk of MACE associated with increased PM_2.5 peak exposure (HR = 0.9991, 95 % CI: 0.9974-1.0008). This lack of association was consistent across sensitivity analyses and different peak definitions, including shorter-term peaks in the five and one years preceding an event.

Conclusions: Our findings suggest that PM_2.5 peak exposure does not significantly increase the risk of MACE in this Danish population. These results challenge the hypothesis that PM_2.5 peaks over a long period are a determinant of cardiovascular risk. Further research is warranted to explore these relationships in different populations and to investigate potential mechanisms underlying the effects of air pollution peaks on cardiovascular health.