Vehicles drive through heavy smog in Delhi
3: The five main sources of air pollution are indoor burning of fossil fuels, wood and other biomass to cook, heat and light homes; industry, including power generation such as coal-fired plants and diesel generators; transport, especially vehicles with diesel engines; agriculture, including livestock, which produces methane and ammonia, rice paddies, which produce methane, and the burning of agricultural waste; and open waste burning and organic waste in landfills.
REUTERS/Cathal McNaughton