ASSESSMENT OF RESUSPENDED DUST CONTRIBUTIONS AND PARTICLE SIZE PROFILE OF PAVED AND UNPAVED ROADS IN MUMBAI

ABSTRACT

The problem of air pollution has been addressed in a variety of manner in metropolitan cities since ages. However, the problems have been always taken as remote and abstract rather than immediate and concrete. The general categories used to prepare the inventory have been referred from identifiable markers such as point, mobile and area sources. Resuspended dust has been recognized to contribute a significant quantity in the urban air pollution, the extent of it, however, it has not well estimated as yet for the city of Mumbai. The contribution of resuspended dust to the total emissions in urban areas is of concern and further studies on these grounds are equally important for complete emission inventory preparation. With a view to assess the extent of contribution of resuspended dust in total emission of Mumbai city, field studies were carried out at four different sites, two each of paved and unpaved roads. The sites were selected taking into consideration the traffic flow, quality of the road, vehicle types on particular roads. A nine-stage cascade impactor sampler was used for sizing of the resuspended dust. The results show that suspended portion of TSP as well as PM10 vary significantly although it is also evident that resuspension contributes to a significant portion of the emission sources. Furthermore, the study revealed that unpaved sites contribute to higher resuspended dust as expected and it is also directly related to the movement on such sites but the effect of wind is marginal. Resuspended dust contributions in TSP was about 7 to 14% and 37 to 47% for paved and unpaved roads respectively, whereas in case of PM10, it was 6 to 21% and 21 to 37% for pave and unpaved roads respectively. Analysis of the particle size distribution showed that the resuspended dust mainly constituted of coarser size particles than the exhaust emission.