Assessment of indoor air quality and housing, household and health characteristics in densely populated urban slums

This study provides the first quantitative assessment of seasonal variation in indoor PM2.5 in the high-air pollution risk and densely populated slums in Mumbai, India and estimates the contributions of indoor and outdoor sources to it. Indoor and outdoor 24-h averaged gravimetric PM2.5 (n(ind )= 20 homes, n(out) = 10 days) was measured during summer (May- June 2016) and winter (January-March 2017). During the summer, real-time PM2.5, Lung Deposited Surface Area and Black Carbon were also measured (n(ind) = 8,n(out)= 8). Additionally, detailed questionnaire surveys on housing, household and health characteristics were conducted in similar to 500 homes of the seven Mumbai slums. More than 60% of the homes in slums had no separate kitchen or cross-ventilation, especially in low socioeconomic status homes. Respiratory and cardiovascular diseases were reported in 15% and 6% of the households, respectively, with a higher prevalence in homes burning mosquito coils. Significantly higher indoor PM2.5 was observed during winter (111 +/- 30 mu g/m(3)) than summer (36 +/- 12 mu g/m(3)). Although liquefied petroleum gas was the only indoor cooking fuel reported, the winter-time indoor levels were similar or higher than the concentrations observed in other urban slum homes using biomass fuels for cooking. This could be attributed to the alarmingly high winter-time ambient PM2.5 (192 +/- 80 mu g/m(3)) and its larger contribution to indoor PM2.5 (81%). On the other hand, the contribution of indoor and local outdoor sources was significantly higher for Lung Deposited Surface Area (33%) and Black Carbon (43%) compared to PM2.5 (19%), which are more fine and toxicity-relevant particle metrics. [GRAPHICS] .