NEW DELHI — Authorities in New Delhi ordered all primary schools to suspend in-person classes until further notice Thursday evening as smog worsened in India’s sprawling capital.

New Delhi and the surrounding metropolitan area, home to more than 30 million people, tops the global rankings for air pollution during winter.

Smog is blamed for thousands of premature deaths each year and is an annual source of misery for the capital’s residents, with various piecemeal government initiatives failing to measurably address the problem.

“Due to rising pollution levels, all primary schools in Delhi will shift to online classes until other directions,” Chief Minister Atishi, who goes by one name, announced on X.com.

Schools are often closed during the worst weeks of the annual smog crisis, which also causes numerous other disruptions in the city.

Authorities also regularly impose bans on construction activity and restrict diesel-fueled freight trucks from other parts of the South Asian country in an effort to mitigate the toxic clouds that blanket the capital.

Gray skies and acrid smog made life a misery for New Delhi residents this week.

Levels of PM2.5 pollutants – dangerous cancer-causing microparticles that enter the blood through the lungs – were recorded at more than 50 times the daily maximum recommended by the World Health Organization on Wednesday.

New Delhi is blanketed in acrid smog every year, primarily from stubble burning by farmers in other parts of India to clear their fields for plowing, as well as from factories and traffic fumes.

Cooler temperatures and slowed winds make matters worse by trapping deadly pollutants every winter from mid-October to at least January.

India’s Supreme Court ruled last month that clean air is a fundamental human right, ordering both the central government and state authorities to take action.

But critics say arguments between rival politicians running neighboring states — as well as between central and state authorities — have exacerbated the problem.

Politicians are accused of not wanting to anger key figures in their constituencies, particularly powerful farming groups.

Authorities in New Delhi have launched several initiatives to combat pollution that have done little in practice.

Government trucks are regularly used to spray water to briefly reduce pollution.

A new scheme unveiled this month to use three small drones to spray water mist has been derided by critics as another “helpful” solution to a public health crisis.

A study in the medical journal The Lancet attributed 1.67 million premature deaths to air pollution in the world’s most populous country in 2019.

New Delhi’s choking carbon smog came as researchers warned that emissions of planet-warming fossil fuels will hit a record high this year, according to new findings from an international network of scientists at the Global Carbon Project .