LONDON — In Pakistan’s Punjab region, record high levels of air pollution have led to hundreds of hospital admissions, school closures and stay-at-home orders, while cities and towns remain shrouded in a thick, toxic smog.

On the outskirts of Lahore, the region’s largest city with 13 million residents, the Air Quality Index rose to 1900 on Sunday, according to IQAir, a Swiss company that monitors air quality around the world. According to IQAir, it was the worst air quality ever recorded in the city, and more than six times higher than the level classified as “hazardous” by the U.S. Environmental Protection Agency.

More than 900 people, including children and the elderly, were hospitalized due to the pollution on Tuesday, according to Marriyum Aurangzeb, a senior minister in the Punjab government.

On Wednesday, the Punjab government ordered all primary and secondary schools to switch to remote learning for 10 days and instructed half of the workforce to stay home. The government also required residents to wear masks.

“This is a critical situation,” Aurangzeb said. “I appeal to the citizens, for God’s sake, not to come out of your houses.”

Authorities have created a ‘smog war room’ to tackle pollution, using strategies such as spraying water on roads, demolishing environmentally damaging brick kilns and banning certain polluting vehicles.

Studies show that the extreme air pollution is caused by the convergence of several factors: farmers in rural areas burn their crops during the winter harvest months to clear their fields; brick kilns blow smoke from the burning of coal near densely populated hubs; and cars that use diesel fuel emit fumes as they drive through cities and make turns.

Aurangzeb blamed the “winds from India” for bringing the smog to Pakistan and said she would write to the Indian government to take concerted efforts to curb pollution.

“Everyone is coughing and having asthma attacks and allergy attacks,” says Sarah Javed, a general practitioner specializing in respiratory problems at Vital Care Hospital in Lahore. She saw an influx of patients coming in with sinus, throat, skin and eye infections due to the smog.

“It reminds us all of the COVID days,” Linda Wali, the principal of a primary school in Lahore, told ABC News. “The students don’t like going online and honestly only half of the students actually take these classes.”

The UN Environment Program estimates that air pollution causes 8 million premature deaths every year and calls it the “greatest environmental threat to public health worldwide”. During winter, the cold air traps particulate matter, making the smog denser and lasting longer.

Doctors recommend residents use humidifiers, air purifiers and masks whenever possible.

“The smog started very early this year and at a very high level,” Javed said. She predicted the problem would only get worse, adding: “Maybe next year the AQI will be over 2,000.”