The oxidative potential (OP) of particulate matter (PM) is a major driver of PM-associated health effects. In India, the emission sources defining PM-OP, and their local/regional nature, are yet to be established. Here, to address this gap we determine the geographical origin, sources of PM, and its OP at five Indo-Gangetic Plain sites inside and outside Delhi. Our findings reveal that although uniformly high PM concentrations are recorded across the entire region, local emission sources and formation processes dominate PM pollution. Specifically, ammonium chloride, and organic aerosols (OA) from traffic exhaust, residential heating, and oxidation of unsaturated vapors from fossil fuels are the dominant PM sources inside Delhi. Ammonium sulfate and nitrate, and secondary OA from biomass burning vapors, are produced outside Delhi. Nevertheless, PM-OP is overwhelmingly driven by OA from incomplete combustion of biomass and fossil fuels, including traffic. These findings suggest that addressing local inefficient combustion processes can effectively mitigate PM health exposure in northern India.
Förderungen Central Pollution Control Board, Government of India J.C. Bose National Fellowship under the aegis of Science and Engineering Research Board, Department of Science and Technology, Government of India Open Philanthropy Clean Air Fund Ultra-high resolution mass spectrometer French Research Agency Predictair- FUGA Grant Department of Space, Government of India Swiss National Science Foundation Ambizione Predictair- FUGA Grant, ACME Swiss National Science Foundation Swiss National Science Foundation Ambizione grant SDC Clean-Air-China Program Swiss National Science Foundation for the project MOLORG French Research Agency - ANR Swiss Development Cooperation (SDC) Clean Air Project in India