Bernstein, DianaHamilton, Douglas S.Krasnoff, RosalieMahowald, Natalie M.Connelly, David S.Tilmes, SimoneHess, Peter G.2021-05-252021-05-252021-05-25https://hdl.handle.net/1813/103740Western North American fires have been increasing in magnitude and severity over the last few decades. The complex coupling of fires with the atmospheric energy budget and meteorology creates short-term feedbacks on regional weather altering the amount of pollution to which Americans are exposed. Using a combination of model simulations and observations, this study shows that the severe fires in the summer of 2017 increased atmospheric aerosol concentrations leading to a cooling of the air at the surface, reductions in sensible heat fluxes, and a lowering of the planetary boundary layer height over land. This combination of lower-boundary layer height and increased aerosol pollution from the fires reduces air quality. We estimate that from start of August to end of October 2017, ~400 premature deaths occurred within the western US as a result of short-term exposure to elevated PM2.5 from fire smoke. As North America confronts a warming climate with more fires the short-term climate and pollution impacts of increased fire activity should be assessed within policy aimed to minimize impacts of climate change on society.en-USAttribution 4.0 International2017 western North American wildfiresair qualitybiomass burning aerosolsdatasethttps://doi.org/10.7298/4ttw-g030