Indoor Air Quality in Multi-Family Housing: Drivers and Interventions

Indoor air pollution is likely to be elevated in multi-family housing and to contribute to health disparities, but limited studies to date have systematically considered the empirical evidence for exposure differentials between multi-family and single-family housing. Our goal is to separately examine the drivers of residential indoor air pollution, including outdoor air pollution, ventilation and filtration, indoor sources, and occupant activity patterns, using secondhand smoke as a case study to examine the behavioral dimensions of indoor environmental interventions.

Within studies published from 2018 to 2023, multi-family homes have higher average outdoor air pollution than single-family homes given their more frequent presence in urban and near-roadway settings. Systematic differences in ventilation were principally related to the presence of working kitchen and bathroom exhaust fans, with heterogeneity in overall building infiltration. Indoor sources such as smoking and cooking were more prevalent in multi-family housing, partly because of the influence of adjacent units and shared spaces and partly because source utilization was higher among sociodemographic groups who tend to live in multi-family housing. The literature on smoke-free housing demonstrated that additional steps would be required to reduce exposure to secondhand smoke given some of the challenges associated with smoking cessation. Publications on the drivers of indoor air pollution in multi-family housing reinforce the likelihood of substantial exposure disparities, indicating the urgency of policy measures that address indoor sources and improve ventilation and filtration in a manner that recognizes the complex behavioral dynamics in the home environment.