Air quality in Indian capital reaches severe levels, posing heightened health risks for more than 30 million residents.

Heavy smog has blanketed New Delhi after firecrackers lit up the Indian capital during Diwali celebrations, worsening the seasonal pollution crisis.

Diwali, the Hindu festival of lights, was celebrated across India on Sunday. Despite restrictions on fireworks, New Delhi residents celebrated the festival of lights with firecrackers throughout Sunday evening, releasing smoke and fine particulate matter into the atmosphere.

On Monday morning, the Air Quality Index exceeded 350 in several parts of the capital, categorised as “severe” and posing significant health risks, according to the World Health Organization’s (WHO) recommended exposure thresholds.

Last month, India’s Supreme Court put in place restrictions to limit Diwali pollution, allowing only approved “green firecrackers” under specified conditions for three-hour windows on Saturday and Sunday. The approved crackers produce fewer emissions but are not pollution-free.

Seasonal pollution

On Wednesday, days before Diwali, toxic air pollution in New Delhi surged to more than 30 times the WHO’s recommended daily limit, data from air monitors showed.

New Delhi, home to 30 million people, persistently ranks among the world’s most polluted capital cities.

The issue is exacerbated during the winter, when 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.

The result is a thick haze that can linger over the capital and surrounding areas for days.