A report released by Greenpeace India, “Out of Sight - How coal burning advances India’s Air Pollution Crisis” reveals coal as the largest overlooked source of air pollution, and identifies air pollution emission hotspots in India visibly linked to thermal power plants in the area. Out Of Sight uses satellite based analysis from 2009 to 2015 which reveals the thermal power plant clusters in Singrauli, Korba – Raigarh, Angul, Chandrapur, Mundra and NCR as the source of SO2 and NO2 emission growth in India over the past five years, showing nationwide increase of 13% and 31% respectively for PM2.5 and SO2. Using similar data earlier studies have shown an increase of 20% in the regional trends for NO2 levels over the last decade. Secondary particulate matter formed by SO2 and NO2 is one of the major contributors to PM2.5 levels: Multiple research studies have emphasised that 30% to 34% of total PM2.5 concentration in India is contributed by the secondary particulates, most of which come from the burning of fossil fuels. Large industrial clusters show up as hotspots of SO2 and NO2 emissions, and it is no coincidence that these major hotspots overlap with the highest coal consumption.