A Hypothetical PM2.5 Intervention for the Risk of Hospitalization for Cardiovascular Diseases.

Importance: There is limited direct evidence of the effects of policies regarding ambient particulate matter with an aerodynamic diameter of 2.5 µm or less (PM2.5) on the risk of hospitalization for cardiovascular diseases (CVD). This evidence is essential for estimating the benefits of meeting specific PM2.5 standards in the regulatory impact analysis. Objective: To estimate the association of strengthening ambient PM2.5 standards with the risk of hospitalization for major CVD outcomes. Design, Setting, and Participants: This population-based study used data from the UK Biobank cohort and followed up the participants from January 1, 2015, to December 31, 2019. All participants were 60 years or older and had no history of hospitalization with a primary diagnosis of a specific CVD at baseline. Data were analyzed from August 1, 2022, to August 25, 2025. Exposures: Annual mean PM2.5 exposure was assigned based on a 1 × 1-km2 resolution PM2.5 model linked to participants' residential locations. Main Outcomes and Measures: The main outcomes were the first hospitalization with a primary diagnosis of stroke, myocardial infarction, heart failure, or arrhythmia. Longitudinal targeted maximum likelihood estimation was used to estimate 5-year hospitalization risks under hypothetical PM2.5 interventions. Results: Among the 502 133 UK Biobank participants recruited from 2006 to 2010 (273 158 [54.4%] female), 307 202 participants met the eligibility criteria for stroke, 304 212 for myocardial infarction, 310 100 for heart failure, and 302 255 for arrhythmia. The median age was 68.0 (IQR, 64.6-71.5) years for stroke, myocardial infarction, and arrhythmia, 68.0 (IQR, 64.7-71.5) years for heart failure, with female participants ranging from 54.4% to 55.0% across cohorts. Compared with no intervention on PM2.5, implementing a stricter ambient PM2.5 standard would reduce the absolute risk of hospitalization for major CVD. It was estimated that for the hypothetical PM2.5 intervention of reducing PM2.5 exposure by 5% if it is above the threshold of 9 µg/m3, the estimated 5-year risk difference of hospitalization for stroke was -2.26 per mille (95% CI, -8.97 to -20.64 per mille); for myocardial infarction, -8.64 per mille (95% CI, -9.16 to -6.38 per mille); for heart failure, -3.20 per mille (95% CI, -4.16 to -1.25 per mille); and for arrythmia, -4.16 per mille (95% CI, -12.70 to 12.93 per mille). For the hypothetical PM2.5 intervention of reducing PM2.5 exposure by 5% if it is above the threshold of 12 µg/m3, the estimated 5-year risk difference of hospitalization for stroke was -1.54 per mille (95% CI, -2.21 to 0.73 per mille). However, the reduction in risk for arrhythmia was not statistically significant (-2.06 per mille [95% CI, -4.79 to 3.12 per mille]). Conclusions and Relevance: In this cohort study using data from the UK Biobank, the absolute risk reduction of hospitalization for stroke, myocardial infarction, heart failure, and arrhythmia due to hypothetical ambient PM2.5 interventions was quantified. The findings suggest the beneficial cardiovascular health impacts of further strengthening the current PM2.5 regulations in the United Kingdom.