64 Additional studies have examined the impact of wildfire-related air pollution on cardiac arrest risk, highlighting the acute cardiovascular threats posed by extreme environmental events. The study Out-of- Hospital Cardiac Arrests and Wildfire-Related Particulate Matter During 2015–2017 California Wildfires by Jones et al. (2020) investigated how exposure to wildfire smoke influences OHCA incidence across affected regions. Wildfires produce high concentrations of fine particulate matter (PM2.5), which can travel hundreds of miles and affect populations far from the fire, creating widespread and unpredictable exposure. These events are particularly concerning because they combine high- intensity air pollution with heat stress and other environmental challenges, increasing the overall cardiovascular burden on exposed populations. The research team examined a de-identified dataset of OHCA events that took place during wildfire periods, with each incident matched to daily PM2.5 air quality measurements specifically resulting from wildfire smoke. Smoke plume density, classified as light, medium, or heavy, was estimated using the NOAA Hazard Mapping System Smoke Product, providing spatially precise exposure data. To capture the compounding effects of environmental stressors, daily temperature and relative humidity were obtained from the University of Idaho Gridded Surface Meteorological Dataset (gridMET) via the Google Earth Engine Data Catalog and aggregated at the census tract level using 4-kilometer grids from NLDAS. These data were used to calculate daily heat index values, integrating temperature and humidity to reflect the combined environmental load on cardiovascular health. Wildfire Smoke and Cardiac Arrest Table 1. Sociodemographic Factors of Patients With OHCA, by Number and Percent Exposed to Wildfire Smoke, in 14 California Counties from May 2015 to October 2017. From Jones et al., Out of Hospital Cardiac Arrests and Wildfire Related Particulate Matter During 2015–2017 California Wildfires, Journal of the American Heart Association 2020;9:e014125. Used with Permission. Licensed under CC BY NC. DOI: 10.1161/JAHA.119.014125.
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