Particulate matter concentrations in social housing

Multifamily buildings generally, and social housing specifically, are an important component of most urban environments. Residents of social housing are often exposed to higher concentrations of indoor pollutants. We measured particulate matter (PM) concentrations in 91 smoking and non-smoking apartments across seven social housing buildings in Toronto, Canada before and after energy retrofits. Particle concentrations varied greatly within and between apartments. Of the four environmental factors examined (smoking, season, building, and retrofit status), only smoking (p < 0.001) had a significant effect across all measurements. PM concentrations were two to three times higher in smoking apartments. PM concentrations in non-smoking apartments from this study were two times higher than comparable measurements from 21 single-family homes in Toronto that used the same particle monitor. A source detection algorithm reported elevated PM concentrations during 57% ± 12% of each monitoring period, which was higher than in the single-family homes, suggesting that indoor sources are likely responsible for the concentration differences. Overall, we found that PM concentrations are disproportionately higher in social housing buildings which likely contribute to health disparities and highlight the importance of exposure reduction strategies in this important urban building type.