Thick smog blanketed India’s capital Tuesday, a day after millions celebrated the Hindu festival of Diwali with fireworks that sent air pollution levels soaring to hazardous levels.

Revelers in New Delhi burst firecrackers late into Monday night, filling the air with smoke and fine particles that mixed with seasonal pollution and stagnant weather conditions.

By Tuesday morning, the city’s Air Quality Index had climbed above 350 in several neighborhoods, a level considered “severe” and dangerous to breathe, according to the World Health Organization’s daily recommended maximum exposure.

Visibility also dropped in some parts of the city as a gray haze enveloped streets, high-rises and historical monuments.

India’s top court last week eased a blanket ban on firecrackers in New Delhi during Diwali, allowing limited use of “green firecrackers” that emit fewer pollutants.

Developed by federal research institutes, they are designed to cut particulate and gas emissions by about 30%.

The court had said they could be used during specific hours from Saturday to Tuesday, but like past years the rule was mostly flouted.

New Delhi and its metropolitan region — home to more than 30 million people — routinely ranks among the world’s most polluted cities during the winter when widespread Diwali fireworks coincide with cooler weather and smoke from crop residue fires set by farmers in nearby states.

Authorities in New Delhi have implemented a set of measures to curb pollution levels, which include limits on construction activity and restrictions on diesel generators.

But environmentalists say long-term solutions, such as cleaner energy and stricter vehicle-emission controls, are needed to prevent the annual crisis.

Rising pollution also cuts the amount of sunshine India receives, a recent study found.

AP video shot by: Piyush Nagpal and Shonal Ganguly