Heavy smog blanketed New Delhi on Monday after residents lit firecrackers during Diwali celebrations on Sunday, despite restrictions imposed by India's Supreme Court to limit pollution.
The Air Quality Index exceeded 350 in several parts of the capital on Monday morning, classified as "severe" and posing significant health risks under World Health Organization exposure thresholds. New Delhi is home to 30 million people.
India's Supreme Court had restricted Diwali fireworks to approved "green firecrackers" during three-hour windows on Saturday and Sunday. These approved crackers produce fewer emissions but are not pollution-free.
On Wednesday, three days before Diwali, toxic air pollution in New Delhi reached more than 30 times the WHO's recommended daily limit, according to air monitor data.
New Delhi persistently ranks among the world's most polluted capital cities. Winter conditions worsen the problem. Cooler temperatures, low wind speeds and stagnant atmospheric conditions prevent pollutants from dispersing. Vehicles account for 23 percent of New Delhi's winter pollution, while biomass burning including farm stubble fires contributes 20 percent, according to India's Ministry of Environment, Forest and Climate Change.