Wildfire smoke indoors: A review of infiltration risk factors and exposure mitigation strategies.

Exposure to the particulate matter (PM2.5) component of wildfire smoke is associated with cardiovascular and respiratory morbidity and mortality. To minimize exposure to high concentrations of PM2.5, public health officials recommend a multipronged mitigation approach through closing all doors and windows and running a portable air cleaner (PAC) indoors to filter particulate from indoor air. Through experimental studies, mitigation efficacy of both remaining indoors and utilizing an air cleaner have been generally validated, but efficacy is inconsistent, depending on building structure and occupant behavior. This leads to difficulties in generalizing mitigation efficacy for the national housing stock to determine overall protection from wildfire smoke. Our review aims to summarize the studies examining smoke infiltration and PAC exposure mitigation efficacy to determine recommendations for building design and retrofit strategies that should be prioritized to minimize harmful exposure.Implications: These results summarize existing evidence from examinations of smoke infiltration and portable air cleaner exposure mitigation efficacy to determine recommendations for building design and retrofit strategies that should be prioritized to minimize harmful exposure.