Thick smog shrouded New Delhi and other cities around South and Southeast Asia as air pollution levels soared Thursday.
Air pollution in the region worsens particularly in winter when the burning of crop residue in agricultural areas coincides with cooler temperatures that trap the smoke. The smoke is blown into cities, where there are more people and where auto emissions further add to the pollution. Emissions from industries without pollution controls and the use of coal to produce electricity are also linked to poor air quality in urban areas.
