Characterization, Source Apportionment and Carcinogenic Risk Assessment of Atmospheric Particulate Matter at Dehradun, situated in the Foothills of Himalayas

Abstract

The Himalayas are often considered pristine environments; however, they can be influenced by transported aerosols emitted from urbanized and industrialized areas. In the present study, atmospheric PM10 and PM2.5 were measured during 2014–15 at a semi-urban site in Dehradun, situated in the Doon valley between the Shivalik range and lesser Himalayas. Based on the information of chemical species associated with the particles, source apportionment study was performed using positive matrix factorization (PMF) model. The carcinogenic risk due to inhalation of PM was calculated through inhalation unit risk. The atmospheric PM showed a seasonal cycle with a maximum during winter (PM10: 90 ± 32 μg m−3; PM2.5: 63 ± 27 μg m−3) and minimum during summer season (PM10: 87 ± 40 μg m−3; PM2.5: 39 ± 19 μg m−3). Identified major sources of atmospheric PM are soil/road dust, vehicular activities, industrial activities, mixed aerosols, and anthropogenic burning. Seasonal variation of sources reveals that during summer, soil/road dust (56%) is the predominant source of PM10, whereas industrial activities (50%) in case of PM2.5. During winter, mixed aerosols comprising of emissions from vehicular activities, biomass and anthropogenic burning (62%) are predominant sources of PM10, whereas industrial activities (42%) in case of PM2.5. The study of aerosol vertical profile using satellite-derived CALIPSO data reveals the presence of polluted aerosol at high altitude (0.6–2.9 km) over Doon valley, suggesting the influence of neighboring polluted Indo-Gangetic Plain (IGP) region during both seasons. The carcinogenic risk assessment revealed that inhalation of PM over Dehradun can cause health risk.