India, Dec. 25 -- A large share of India's PM2.5 pollution is not emitted directly but is chemically formed in the atmosphere from precursor gases, with 42 per cent of the burden being secondary particulate matter, primarily ammonium sulfate formed from sulfur dioxide (SO2). India is the largest SO2 emitter globally, with coal-fired power plants contributing at least 60 percent of national SO2 emissions, reinforcing the central role of SO2 control in reducing PM2.5 pollution.

The Centre for Research on Energy and Clean Air (CREA) in its study shows that a large share of India's PM2.5 pollution is not emitted directly, but is chemically formed in the atmosphere from precursor gases. The assessment finds that up to 42 percent of India's PM...