The city has closed all schools, halted construction and said it would impose restrictions on vehicle use.

Depending on legal approval and weather conditions, the local environment minister said authorities will try to induce rain from around November 20.

Air quality in the city typically worsens every year ahead of winter, when cold air traps pollutants from sources including vehicles, industry, construction dust and agricultural burning.

“It is likely that if the current weather conditions continue, the pollution will not subside this week or sometime in the future,” Delhi Environment Minister Gopal Rai told reporters.

Mr Rai said a proposal prepared by experts on rainmaking would be presented to the Supreme Court on Friday. “I believe that with the conditions we have and if we get support from the people, we can at least conduct an experimental rainmaking exercise,” he said.

China, Indonesia and Malaysia have previously carried out similar rain-seeding operations. India's environment ministry said it plans to seed clouds, a technique that uses substances such as silver iodide to induce rainfall.

The city's air quality index was above 320 on Wednesday morning (November 8), a level classified as "hazardous" by Swiss group IQAir, before dropping to 294 later.

Quoc Thien (according to Reuters)