Effects of intermediate and long-term exposure to ambient air pollution and temperature on hospital admissions with second cardiovascular events among medicare beneficiaries

Mahdieh Danesh Yazdi; Yaguang Wei; Qian Di; Weeberb J Requia; Adjani A Peralta; Francesca Dominici; Joel D Schwartz

doi:10.1016/j.envint.2025.109617

Effects of intermediate and long-term exposure to ambient air pollution and temperature on hospital admissions with second cardiovascular events among medicare beneficiaries

Environ Int. 2025 Jun 24:202:109617. doi: 10.1016/j.envint.2025.109617. Online ahead of print.

Authors

Mahdieh Danesh Yazdi¹, Yaguang Wei², Qian Di³, Weeberb J Requia⁴, Adjani A Peralta⁵, Francesca Dominici⁶, Joel D Schwartz⁷

Affiliations

¹ Program in Public Health, Department of Family, Population, and Preventive Medicine, Renaissance School of Medicine at Stony Brook University, Stony Brook, NY, USA; Department of Environmental Health, Harvard TH Chan School of Public Health, Boston, MA, USA. Electronic address: mahdieh.daneshyazdi@stonybrookmedicine.edu.
² Department of Environmental Health, Harvard TH Chan School of Public Health, Boston, MA, USA; Department of Environmental Medicine and Climate Science, Icahn School of Medicine at Mount Sinai, New York, NY, USA.
³ Vanke School of Public Health, Tsinghua University, Beijing, China.
⁴ Center for Environment and Public Health Studies, School of Public Policy and Government, Fundação Getulio Vargas, Brasília, Distrito Federal, Brazil.
⁵ Department of Environmental Health, Harvard TH Chan School of Public Health, Boston, MA, USA.
⁶ Department of Biostatistics, Harvard TH Chan School of Public Health, Boston, MA, USA.
⁷ Department of Environmental Health, Harvard TH Chan School of Public Health, Boston, MA, USA; Department of Epidemiology, Harvard TH Chan School of Public Health, Boston, MA, USA.

PMID: 40578117
DOI: 10.1016/j.envint.2025.109617

Abstract

Background: Air pollution has been linked to cardiovascular diseases (CVDs). In this study, we assess whether exposure to air pollutants and ambient temperature is associated with repeated admissions with adverse cardiovascular outcomes.

Methods: We used data from Medicare beneficiaries between 2000 and 2016 to look at the effects of intermediate and long-term exposure to ambient PM_2.5, NO₂, O₃, and temperature on second admissions with myocardial infarction (MI) and ischemic stroke. We derived exposure levels from high-resolution spatiotemporal models. We adjusted for demographic, socioeconomic, and access-to-care characteristics. Cox proportional hazards models were used to assess these relationships. We further looked at the effects of exposure at lower air pollution concentrations defined as PM_2.5 < 9 µg/m³, NO₂ < 25 ppb, and O₃ < 50 ppb.

Results: PM_2.5 and NO₂ increased the hazard of second admissions with both MI and stroke. For PM_2.5, the effects were more pronounced for longer exposure time windows. Each µg/m³ increase in one-year PM_2.5 levels before the first admission increased the hazard of a second admission with MI by 1.1% (95% CI: 1.0%-1.2%) and stroke by 0.9% (95% CI: 0.8%-1.1%). O₃ exhibited a slight protective effect for both outcomes. Higher temperatures were associated with a higher hazard of second admissions with stroke. These results persisted at lower concentrations.

Conclusion: Our study demonstrates that exposures to PM_2.5 and NO₂ are associated with increased rates of second admissions with MIs and strokes. Higher temperatures were also further associated with an increase in the rate of second admissions with stroke.

Keywords: Air pollution; Ischemic stroke; Myocardial infarction; Second events; Temperature.