The impacts of air pollution on public health have become great concerns worldwide. Particulate matter with an aerodynamic diameter small than 2.5μm (PM2.5), either from conventional sources such as traffic emissions or wildfire smoke, is among the most damaging air pollutants and has been documented to cause both acute and chronic diseases and their exacerbations. Owing to increasing economic activities, consumption of natural gasses, and wildfires, the concentration of PM2.5 in the United States climbed back again. Compared with a large body of research summarizing PM2.5 chronic effects on health, fewer studies focused on its acute health impacts. We conducted a narrative review of the available epidemiology studies evaluating the associations between short-term PM2.5 exposure and acute health outcomes including work loss days. Compared to the studies investigating wildfire PM2.5 effects, we found a larger body of evidence indicating the acute impact of conventional PM2.5 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 PM2.5 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 PM2.5exposure is also needed to inform public health interventions.