 Previous studies have shown that smoke from wildfires can have negative effects on both outdoor and indoor air quality. This study examined the relationship between indoor and outdoor air quality on smoke-impacted days in the western United States in 2020. It was found that indoor air quality was significantly worse than outdoor air quality on smoke-impacted days, with indoor air quality being up to 82% higher than outdoor air quality. Additionally, it was found that the indoor-outdoor PM underscore 2.5 ratio was less than one on smoke-impacted days, meaning that indoor air quality was generally lower than outdoor air quality. On heavily smoke-impacted days, indoor air quality could be as much as 2.1 times higher than outdoor air quality. Furthermore, it was found that the amount of indoor air pollution increased with each 10 g m cubed increase in outdoor air pollution. This article was authored by Caitlin Adele, Born Ford, Jesse Burkhart, and others. We are article.tv, links in the description below.