Summary: The impacts of air pollution on public health have become a great concern worldwide. Particulate matter with an aerodynamic diameter smaller than 2.5μm (PM_2.5), either from conventional sources such as traffic emissions or wildfire smoke, is among the most damaging air pollutant and has been documented to cause both acute and chronic diseases and their exacerbations. Owing to increasing economic activities, consumption of natural gases, and wildfires, the concentration of PM_2.5 in the United States climbed again. Compared with a large body of research summarizing PM_2.5 chronic effects on health, fewer studies focused on its acute health impacts.

Findings: Authors conducted a narrative review of the available epidemiology studies evaluating the associations between short-term PM_2.5 exposure and acute health outcomes including work loss days. Compared to the studies investigating wildfire PM_2.5 effects, they found a larger body of evidence indicating the acute impact of conventional PM_2.5 exposure on various health effects, especially on respiratory and cardiovascular disorders, including related to emergency and hospital visits, as well as disease-specific and all-cause mortalities. More studies are needed to fully understand the extent of the acute health impact of PM_2.5 exposure from both sources, especially from wildfires, and on neuropsychological, and metabolic disorders and birth outcomes; and on outcomes such as work loss days, which are not perceived as severe enough to necessitate medical assistance but affect a large population.

More research on vulnerable populations from wildfire PM_2.5 exposure is also needed to inform public health interventions.