Ranu Gadi and Shivani
The National Capital Region (NCR) of India is experiencing high atmospheric pollution with increasing population and intensive human activities, including economic and social activities. The impact of anthropogenic emissions on the air quality revealed the high particulate levels in the atmosphere. Atmospheric particulate matter includes organic aerosols as significant and variable fraction. Estimation of organic matter in the ambient atmosphere is important due to their carcinogenic and/or mutagenic properties and association with indirect climate forcing. Organic aerosols contain numerous compounds including molecular markers (n-alkanes, hopanes and steranes, PAHs, levoglucosan, phthalates) which are defined as chemically inert and source-specific compounds. Hence, they can be used as tracers to determine the source contribution to particulate matter levels in the ambient atmosphere. This study emphasizes the effort made to characterize organic matter in fine ambient aerosols (PM2.5) over the NCR of India. Aerosols samples for PM2.5 (24 hour average) were collected at three (Delhi, Modinagar, Harayana) sites in the NCR during December 2016-December 2017. The average PM2.5 concentration were 124.9 ± 81, 120.1 ± 84.2 and 93.5 ± 59.5 µg m-3 at IG, MN and HR site respectively. The samples were analyzed for the different classes of organic compounds. The source contribution for organic compounds was assessed using Positive Matrix Factorization (PMF) and Principal Component Analysis (PCA). PCA and PMF has extracted five major emission sources: vehicular emissions, biomass burning, cooking emissions, plastic and waste burning and secondary organic carbon for PM2.5 over NCR. Source apportionment inferences signifies the immediate implementation of emissions reduction strategies with special target on transport sector and biomass burning over the NCR of India. Health risk associated with human exposure to PAHs and Phthalates was assessed via inhalation pathway. 3-day backward trajectory analysis explained the local, regional and long range transport routes of PM2.5 for all sites. These results provide important information for future assessment of health risk to the local population, levels of exposure and implementation of pollution control strategies.
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