Government data showed the air quality index over the last two days crossed 400, indicating severe conditions that put people with healthy lungs as well as those with respiratory illnesses at risk.
With the skies over Delhi clouded with smog, many also cast worried eyes on the fate of India-Bangladesh Twenty20 cricket match scheduled for Sunday.
"I do not think any match should happen here in Delhi until the pollution level comes under control," said Gautam Gambhir, a
former Indian test cricketer and the ruling Bharatiya Janata Party's lawmaker in Delhi.
Pollution has worsened over the last week due to the burning of crop residue in neighbouring states that have sent over clouds of hazardous smoke, cloaking the city in a dusty, toxic translucence.
Authorities have had little success in curbing the fires.
On Wednesday, satellites captured more than 2,400 farm fires across Punjab, Haryana and Uttar Pradesh that together contributed 35% of overall air pollution in Delhi, the highest this season, according to government-run monitor SAFAR.
The smoke from the fields combines with urban pollution from vehicles and industry to make New Delhi the world's most polluted capital.
SMOG STOPS PLAY?
Bangladeshi cricketers spent more than two hours at the nets under the smoggy skies on Thursday. Liton Das, the only one wearing a mask, shrugged off concerns over air quality.
"No, no, nothing like that," he said.
Asked if the players had trouble spotting the white ball in the haze, he said, "Well, there will be light in a night game, so it should not be a problem."
As the Bangladeshi players and coaches practised, the air quality index around the stadium was above 400. The index measures the levels of PM 2.5, tiny particulate matter that goes deep into the lungs. Anything above 60 is considered unhealthy.
Rohit Sharma, who will lead the India team, said he had not yet assessed the situation.
"I know the game is scheduled to be played on the third, and it will be played on the third," Sharma told reporters.
Delhi's chief minister Arvind Kejriwal will restrict the use of private vehicles on the city's roads from next week and authorities have shut down construction activity and coal-based power plants.
Deadly air pollution can cut life expectancy by up to seven years in northern India, according to a study by Energy Policy Institute at the University of Chicago.