The air quality in the Indian national capital plummeted to the "severe" category after remaining in the "very poor" level for the past seven days.
On Tuesday, the air quality index in New Delhi crossed 400, prompting the government to issue health warnings for the 12th time in two months.
Officials have been warned against stepping out of their homes and exposing themselves to the toxic environment.
In November, schools in the city were forced to shut down for four days after the index climbed past 500.
Israeli strikes kill 26 in Gaza, health officials say
US government starts likely brief shutdown as House fails to approve deal
Thousands demonstrate in Minnesota and across US to protest ICE
France tightens infant milk rules after recalls
Modi ally proposes social media ban for India's teens as global debate grows
