NEW DELHI — The fireworks have fizzled. The festival lights are coming down. What's left of the Hindu holiday of Diwali in the Indian capital — already considered the world's most polluted — is a toxic haze that has residents gagging for oxygen and hiding indoors.
Air pollution levels across New Delhi on Thursday, a day after the ancient festival of lights, were described as severe-to-critical, up to eight times higher than what India deems acceptable and 20 times what's recommended by the World Health Organization.
Such pollution happens every year, as offices and businesses shut down for India's biggest gift-giving holiday and many gather outdoors to set off powerful rockets at all hours of the night.
A government health advisory this week warned people to avoid all outdoor physical activity, citing a serious risk of respiratory effects following prolonged exposure to smoke-filled air.
Indian tourist Bazil Antonius, visiting from the northern city of Chandigarh, said he had trouble breathing Wednesday night as fireworks exploded overhead.
"Diwali is a lovely festival of lights," Antonius said. "But the fireworks cause a little bit of pollution, which is adding to the pollution already in Delhi."
Restaurant worker Naresh Maggo, 29, said he still looked forward to bursting small fireworks with his children, but that the noise and air pollution made him think "we shouldn't overdo it."
Public alarm over rising pollution has seized the capital in recent years, with newspapers carrying regular stories on levels of particulate matter called PM2.5 — small enough to penetrate deep into the lungs and cause disease. Last year, WHO named the Indian capital as the world's most polluted, with 12 other Indian cities ranking among the world's most polluted 20. Another study in February estimated 660 million Indians, about half of the country's 1.25 billion population, were losing three years of their lives due to exposure to air pollution across the country.
New Delhi is the only Indian city with a network of air quality monitors, and public health experts said pollution levels on Thursday were alarming.
"The intensity was no less, and the pollution level appeared to be quite high," said K. Srinath Reddy, president of the Public Health Foundation of India. He said Delhi dwellers, even if concerned about pollution from fireworks, may still be motivated by a desire to show off to their neighbors.
The sale of fireworks is unregulated in India, and there are no reliable statistics showing how many were sold before the holiday.
The Center for Science and Environment, a Delhi-based research and advocacy group, said its exposure monitoring on Diwali night found pollution levels were slightly lower than in previous years, but still unacceptably high. Between 8 p.m. and midnight, PM2.5 levels were at 399-608 micrograms per cubic meter in some places — well above the Indian limit of 60 and the WHO recommendation of 25. At some points, spikes in pollution were "frightening," hitting more than 2,500, it said.
"Delhiites will have to do a lot more to control crackers to reduce such dangerous levels of exposure and protect public health," the center's executive director, Anumita Roy Chowdhry, said in a statement.
India, like its giant neighbor China, has seen pollution skyrocket with rapid economic growth and a reliance on burning coal to generate electricity. It has also seen an explosion in the number of vehicles on the road, while hundreds of millions of impoverished people still use wood, kerosene or whatever they can grab at the garbage dump to build fires for cooking or keeping warm on winter nights.
Indian officials have imposed a number of measures in hopes of clearing the air, including making emissions standards for cars and industries more strict and imposing a tax on diesel-guzzling trucks that want to enter the city. Since New Delhi began collecting those taxes last week, 30 percent fewer trucks have opted to pass through the city.
In probably the first case of its kind, the Supreme Court is hearing a suit brought on behalf of three babies, the eldest 14 months old, seeking a ban on the use of firecrackers during the festival season to protect the children's fragile immune systems from the impact of pollution. Children are more vulnerable to developing lung ailments including asthma and bronchitis, as well as damage to their cognitive abilities and nervous systems.