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Alaskan wildfires have major ecological, social, and economic consequences, but associated health impacts remain unexplored. We estimated cardiorespiratory morbidity associated with wildfire smoke (WFS) fine particulate matter with a diameter less than 2.5 μm (PM_2.5) in three major population centers (Anchorage, Fairbanks, and the Matanuska‐Susitna Valley) during the 2015–2019 wildfire seasons. To estimate WFS PM_2.5, we utilized data from ground‐based monitors and satellite‐based smoke plume estimates. We implemented time‐stratified case‐crossover analyses with single and distributed lag models to estimate the effect of WFS PM_2.5on cardiorespiratory emergency department (ED) visits. On the day of exposure to WFS PM_2.5, there was an increased odds of asthma‐related ED visits among 15–65 year olds (OR = 1.12, 95% CI = 1.08, 1.16), people >65 years (OR = 1.15, 95% CI = 1.01, 1.31), among Alaska Native people (OR = 1.16, 95% CI = 1.09, 1.23), and in Anchorage (OR = 1.10, 95% CI = 1.05, 1.15) and Fairbanks (OR = 1.12, 95% CI = 1.07, 1.17). There was an increased risk of heart failure related ED visits for Alaska Native people (Lag Day 5 OR = 1.13, 95% CI = 1.02, 1.25). We found evidence that rural populations may delay seeking care. As the frequency and magnitude of Alaskan wildfires continue to increase due to climate change, understanding the health impacts will be imperative. A nuanced understanding of the effects of WFS on specific demographic and geographic groups facilitates data‐driven public health interventions and fire management protocols that address these adverse health effects.

Emissions of C₂‐C₅alkanes from the U.S. oil and gas sector have changed rapidly over the last decade. We use a nested GEOS‐Chem simulation driven by updated 2011NEI emissions with aircraft, surface, and column observations to (1) examine spatial patterns in the emissions and observed atmospheric abundances of C₂‐C₅alkanes over the United States and (2) estimate the contribution of emissions from the U.S. oil and gas industry to these patterns. The oil and gas sector in the updated 2011NEI contributes over 80% of the total U.S. emissions of ethane (C₂H₆) and propane (C₃H₈), and emissions of these species are largest in the central United States. Observed mixing ratios of C₂‐C₅alkanes show enhancements over the central United States below 2 km. A nested GEOS‐Chem simulation underpredicts observed C₃H₈mixing ratios in the boundary layer over several U.S. regions, and the relative underprediction is not consistent, suggesting C₃H₈emissions should receive more attention moving forward. Our decision to consider only C₄‐C₅alkane emissions as a single lumped species produces a geographic distribution similar to observations. Due to the increasing importance of oil and gas emissions in the United States, we recommend continued support of existing long‐term measurements of C₂‐C₅alkanes. We suggest additional monitoring of C₂‐C₅alkanes downwind of northeastern Colorado, Wyoming, and western North Dakota to capture changes in these regions. The atmospheric chemistry modeling community should also evaluate whether chemical mechanisms that lump larger alkanes are sufficient to understand air quality issues in regions with large emissions of these species.