Background The impact of short‐term exposure to fine particulate matter with a diameter ≤2.5 μm (PM 2.5 ) due to wildland fire smoke on the risk of cardiovascular disease (CVD) remains unclear. We investigated the association between short‐term exposure to wildfire smoke PM 2.5 and emergency department visits for acute CVD in the western United States from 2007 to 2018. Methods We analyzed 49 759 958 emergency department visits for primary or secondary diagnoses of atrial fibrillation (AF), acute myocardial infarction, heart failure, stroke, and total CVD across 5 states. Daily smoke, nonsmoke, and total PM 2.5 were estimated using a 1‐km resolution satellite‐driven multistage model and were aggregated to the zip code level. A case‐crossover study design was used, adjusting for temperature, relative humidity, and day of the year. Results The mean smoke PM 2.5 was 1.27 (interquartile range, 0–1.29) μg/m 3 . A 10‐μg/m 3 increase in smoke PM 2.5 was associated with a minuscule decreased risk for AF (odds ratio, 0.994 95% CI, 0.991–0.997), heart failure (odds ratio, 0.995 95% CI, 0.992–0.998), and CVD (odds ratio, 0.997 95% CI, 0.996–0.998) but not for acute myocardial infarction and stroke. Adjusting for nonsmoke PM 2.5 did not alter these associations. A 10‐μg/m 3 increase in total PM 2.5 was linked to a small increased risk for all outcomes except stroke (odds ratio for CVD, 1.006 95% CI, 1.006–1.007). Associations were similar across sex and age groups. Conclusions Short‐term wildfire smoke PM 2.5 exposure was unexpectedly associated with a slightly lower risk of CVD emergency department visits. Whether these findings are due to methodological issues, behavioral changes, or other factors requires further investigation.
Li et al. (Fri,) studied this question.