EFFECT OF NATURAL AND FORCED VENTILATION SYSTEMS ON DECAY AND DEPOSITION RATES OF PARTICLES PRODUCED BY INDOOR SOURCES IN INDIAN URBAN HOUSEHOLDS

摘要

The decay rate of indoor air particulates represents their removal rates and is an important process in the context of indoor air quality. In this study, the decay and deposition rate of particulates is estimated in typical Indian urban kitchens. The overall decay rate of particulate was determined by raising the particle concentration by smoldering of Benzoin, then measuring the concentration variation with time of various particle size (0.05 - 3.2 μm) with a quartz crystal microbalance impactor. The mass size distribution of Benzoin was lognormal with MMAD 0.8μm and produced size distributions consistently through out the experiments. Even though, there is considerable variation in the observed decay rate between houses, the exhaust fan decay rates were greater than that of natural ventilation followed by electric chimney and no ventilation condition. The size segregated particle decay rates varied in a wide range under the exhaust fan and natural ventilation conditions compared to no ventilation conditions. A numerical model has been used to calculate the deposition rate on to smooth surfaces and the observed deposition rates were consistent with the predicted trend.