Western 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 PM_2.5 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.

在过去的几十年里，北美西部火灾的规模和严重程度一直在增加。火灾与大气能量收支和气象的复杂耦合产生了对区域天气的短期反馈，从而改变了美国人所接触的污染量。该研究结合模型模拟和观测，表明 2017 年夏季的严重火灾增加了大气气溶胶浓度，导致地表空气冷却、显热通量减少以及行星边界层降低高于陆地的高度。较低边界层高度和火灾造成的气溶胶污染增加的结合降低了空气质量。我们估计，从 8 月初到 2017 年 10 月底，_2.5起火冒烟。由于北美面临着更多火灾的变暖气候，因此应在旨在最大限度减少气候变化对社会影响的政策内评估火灾活动增加对短期气候和污染的影响。