Background: As wildfires intensify in a warming climate, prolonged exposure to smoke-derived fine particulate matter (PM2.5) poses significant health risks. However, the cardiovascular impacts of long-term cumulative exposure to smoke PM2.5 remain understudied.
Objectives: To investigate associations between long-term cumulative exposure to wildfire smoke PM2.5 and first cardiovascular disease (CVD) hospitalizations among U.S. Medicare beneficiaries and assess potential effect modification by sociodemographic factors.
Methods: This population-based cohort study analyzed 65.2 million Medicare beneficiaries (age ≥65 years) across the contiguous U.S. from 2017-2022. Wildfire smoke PM2.5 was estimated using a spatiotemporal model at 10 × 10 km resolution and assigned to beneficiaries' residential ZIP codes. We applied quasi-Poisson regressions to estimate relative risks (RRs) of CVD hospitalizations for each decile of wildfire smoke PM2.5 concentrations, using exposures below the 1st percentile (0.08 µg/m³) as reference.
Results: Three-year average wildfire smoke PM2.5 was significantly associated with increased CVD hospitalization risk. We observed a non-linear pattern peaking at moderate exposure levels (0.26-0.32 µg/m³) for overall CVD (RR=1.04, 95% CI: 1.03-1.05), ischemic heart disease (RR=1.07, 95% CI: 1.06-1.09), and arrhythmias (RR=1.06, 95% CI: 1.04-1.07). Cerebrovascular hospitalizations showed an increasing trend across exposure levels. Beneficiaries of lower socioeconomic status are potentially more vulnerable.
Conclusions: Long-term cumulative wildfire smoke PM2.5 exposure is associated with elevated CVD hospitalization risk, varying by exposure levels and individual characteristics. These findings underscore the need for targeted public health strategies to mitigate cardiovascular risks among older adults in wildfires.
Editors
Editor-in-Chief
Harlan M. Krumholz, MD, SM, FACC
CME Editor
Ragavendra R. Baliga, MD
Author
Kai Chen, PhD
Important Dates
Date of Release: September 1, 2026
Term of Approval/Date of CME/MOC Expiration: August 31, 2027