Indian authorities have ordered firefighters in the capital to sprinkle water from high-rise buildings to settle dust and stop garbage fires and have banned construction activity amid hazardous air quality affecting millions of people.

New Delhi recorded one of the highest pollution levels of the year on Sunday with the air quality index, measuring sulfur dioxide, carbon monoxide and nitrogen dioxide, touching 450.

The air started improving Wednesday with an increase in wind speed. However, the level of PM 2.5, tiny particulate matter that can dangerously clog lungs, exceeded 320 on Thursday, more than 13 times beyond what the World Health Organization considers safe.

A government advisory asked people to avoid jogging and use masks.

India’s air pollution comes mostly from diesel fuel-burning vehicles, coal-fired power plants and crop burning.

In this Wednesday, Dec. 26, 2018, photo, a motorcyclist rides wearing pollution masks in New Delhi, India. (AP Photo/Manish Swarup)
In this Wednesday, Dec. 26, 2018, photo, a motorcyclist rides wearing pollution masks in New Delhi, India. (AP Photo/Manish Swarup)
In this Wednesday, Dec. 26, 2018, photo, a boy selling tea awaits customers early morning amidst smog in New Delhi, India. (AP Photo/Manish Swarup)
In this Wednesday, Dec. 26, 2018, photo, a boy selling tea awaits customers early morning amidst smog in New Delhi, India. (AP Photo/Manish Swarup)
In this Wednesday, Dec. 26, 2018, photo, Indian military personals walk amidst morning smog in New Delhi, India. (AP Photo/Manish Swarup)
In this Wednesday, Dec. 26, 2018, photo, Indian military personals walk amidst morning smog in New Delhi, India. (AP Photo/Manish Swarup)

Source: The Associated Press