Changes to indoor air quality as a result of relocating families from slums to public housing.

One largely unstudied benefit of relocating families from slums to public housing is the potential improvement in indoor air quality (IAQ). We compared families that moved from slums to public housing with those that remained living in slums in Santiago, Chile in terms of fine particulate matter (PM2.5) as main indicator of change. A cross-sectional study of 98 relocated families and 71 still living in slums was carried out, obtaining indoor and outdoor samples by a Personal Environmental Monitor. Home characteristics, including indoor air pollution sources were collected through questionnaires. Multivariate regression models included the intervention (public housing or slum), indoor pollution sources, outdoor PM2.5 and family characteristics as predictors. Indoor PM2.5 concentrations were higher in slums (77.8 mg m 3 [SD 1⁄4 35.7 mg m 3]) than in public housing (55.7 mg m 3 [SD 1⁄4 34.6 mg m 3], p < 0.001). Differences between indoor and outdoor PM2.5 were significant only in the slum houses. The multivariate analysis showed that housing intervention significantly decreased indoor PM2.5 (10.4 mg m 3) after adjusting by the other predictors. Outdoor PM2.5 was the main predictor of indoor PM2.5. Other significant factors were water heating fuels and indoor smoking. Having infants 1e23 months was associated with a lowering of indoor PM2.5. Our results suggest that a public housing program that moves families from slums to public housing improves indoor air quality directly and also indirectly through air pol-