FILE - In this Saturday, Nov. 2, 2019, file photo, an Indian Hindu devotee performs rituals in the Yamuna river, covered with chemical foam caused by industrial and domestic pollution, during Chhath Puja festival in New Delhi, India. Schools have reopened in the Indian capital with toxic air level coming down by more than half since authorities declared a health emergency last Friday.  Authorities are tackling a large amount of toxic foam floating in the Yamuna River, caused partly by high ammonia levels emanating from industrial pollutants. (AP Photo/Altaf Qadri, File)

NEW DELHI (AP) — Schools reopened on Wednesday in the Indian capital with toxic air level coming down by more than half since authorities declared a health emergency last weekend.

With strong winds blowing away pollutants, the air quality index at the U.S. Embassy in New Delhi read 155 as compared to 500 over the weekend that was 10 times the recommended WHO level.

Air pollution in New Delhi peaks around Nov. 1 due to smog from festival fireworks and smoke from the burning of stubbles in agricultural fields.

A Supreme Court-appointed panel temporarily banned construction activity in the New Delhi region to control the dust in the air.

Authorities also barred smoke-spewing cargo trucks from city streets, experimented at limiting the number of cars on the road and tried to snuff out stubble and garbage fires and ordered builders to cover construction sites to stop dust from enveloping the area.

But the battle is not over as authorities tackle a large amount of toxic foam floating in the Yamuna River, caused partly by high ammonia levels emanating from industrial pollutants. A weekend Hindu festival saw thousands of devotees offering prayers standing in the foam.

Water from the river is chemically treated before being supplied to Delhi's nearly 20 million residents as drinking water.

"The water is absolutely black in color," said Hari Lal, a New Delhi resident who was on the river bank Wednesday. "The water is all chemical."

Kujan Sahani, a worker from eastern Bihar state, complained that his nose and eyes burned and he was feeling breathlessness.

Environmental activists say many rivers across India have become dirtier as the country's economy develops, with city sewage, farming pesticides and industrial effluents freely flowing into waterways despite laws against polluting.

FILE - In this Saturday, Nov. 2, 2019, file photo, an Indian Hindu devotee performs rituals in Yamuna river, covered by chemical foam caused due to industrial and domestic pollution, during Chhath Puja festival in New Delhi, India. Schools have reopened in the Indian capital with toxic air level coming down by more than half since authorities declared a health emergency last Friday.  Authorities are tackling a large amount of toxic foam floating in the Yamuna River, caused partly by high ammonia levels emanating from industrial pollutants. (AP Photo/Altaf Qadri, File)