Joint Impacts of Ambient Air Pollution and Temperature on Cardiovascular Disease in West Florida

Background Ambient temperature and fine particulate matter with an aerodynamic diameter ≤2.5 μm (PM 2 . 5 ) are well‐established contributors of acute cardiovascular events, but their joint short‐term effects in subtropical coastal regions have not been well characterized. We evaluated their joint associations with major cardiovascular outcomes in West Florida. Methods We analyzed daily hospital admissions for myocardial infarction, heart failure, and stroke within the BayCare Health System from 2017 to 2024. Daily mean temperature and PM 2 . 5 were obtained from national monitoring networks. Joint exposure–response relationships were estimated using distributed‐lag generalized additive models with tensor‐product interactions across lags 0 to 7 days, adjusting for temporal trends, day of week, and copollutants. Effect modification by age, sex, and race was examined. Results Temperature showed stronger short‐term associations with cardiovascular risk than local PM 2 . 5 . Among adults aged ≥65 years, myocardial infarction risk was higher at lower temperatures, compared with higher temperatures (relative risk comparing the 75th versus the 25th percentile of the exposure distribution [RR 75 / 25 ], 0.92 [95% CI, 0.89–0.95]). Heart failure exhibited a U‐shaped temperature–risk relationship, with greater heat‐related risk observed among younger adults (RR 75 / 25 , 1.05 [95% CI, 1.02–1.09]) and Black patients (RR 75 / 25 , 1.05 [95% CI, 1.02–1.09]). In contrast, PM 2 . 5 showed weaker overall associations, with only a modest elevation in stroke risk among Black patients (RR 75 / 25 , 1.02 [95% CI, 0.96–1.08]). Joint exposure surfaces revealed outcome‐specific nonlinear patterns, particularly for heart failure at higher temperature and PM 2 . 5 . Conclusions Temperature and PM 2 . 5 jointly influence short‐term cardiovascular risk through nonlinear and subgroup‐specific pathways, highlighting the need for integrated climate and air‐quality strategies to reduce cardiovascular disparities.