Abstract:
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 (nind = 20 homes, nout = 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 (nind = 8, nout = 8). Additionally, detailed questionnaire surveys on housing, household and health characteristics were conducted in ~ 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 μg/m3) than summer (36 ± 12 μg/m3). 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 μg/m3) 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. Graphic abstract: [figure not available: see fulltext.]. © 2021, the author(s), under exclusive licence to springer nature b.v.