Environment/Climate Change
Medium-term exposure to wildfire smoke PM2.5 and cardiorespiratory hospitalization risks Yaguang Wei* Yaguang Wei Edgar Castro Kanhua Yin Alexandra Shtein Bryan N. Vu Mahdieh Danesh Yazdi Longxiang Li Yuxi Liu Adjani A. Peralta Joel Schwartz
Background: Wildfire activity in the US has increased significantly in recent decades. Smoke PM2.5, a primary wildfire emission, can spike for months after a wildfire begins, yet large-scale evidence of its health effects remains limited.
Methods: Hospitalization records for the residents of 16 US states between 2006–2016 were obtained from the State Inpatient Databases. Daily smoke PM2.5 at 10 km2 grid cells across the contiguous US were estimated using a machine learning model that incorporated ground, satellite, and reanalysis data, and were aggregated to ZIP codes to match the spatial resolution of the hospitalization records. We developed a novel self-controlled design, a case-crossover variant, to examine associations between 3-month average exposure to smoke PM2.5 and hospitalization risks for a comprehensive range of cardiovascular (ischemic heart disease, cerebrovascular disease, heart failure, arrhythmia, hypertension, other cardiovascular diseases) and respiratory diseases (acute respiratory infections, pneumonia, COPD, asthma, other respiratory diseases). We further assessed effects of single-month lagged exposures and explored subgroup differences based on neighborhood- and individual-level characteristics.
Results: We found that 3-month average exposure to smoke PM2.5 was associated or marginally associated with increased hospitalization risks for most cardiorespiratory diseases. Results for single-month lagged exposures suggested that these effects persisted up to 3 months after exposure. Subgroup analyses showed larger effects in neighborhoods with higher deprivation levels or greater vegetation, as well as among ever-smokers.
Conclusions: Our findings provided unique insights into the medium-term cardiorespiratory effects of smoke PM2.5, which can persist for months, even after a wildfire has ended.
