The air quality in Delhi remained in the “severe” category as a thick haze enveloped the city Delhi on Tuesday, PTI reported. The overall Air Quality Index was recorded at 404 at noon, according to the Central Pollution Control Board.

The overall level of PM2.5 (particles in the air with a diameter of less than 2.5 micrometres) was 238 while the and PM10 (particles in the air with a diameter of less than 10 micrometres) reading was 399.

At least 17 areas in the city recorded “severe” air quality and 14 locations recorded “very poor” quality. Sporadic rainfall, expected on Tuesday and Wednesday, may worsen the pollution levels, said authorities.

“Such isolated showers often aggravate air pollution post event unless the spell is longer and widespread,” said a report from the Centre-run System of Air Quality and Weather Forecasting. “It introduces a lot of moisture in the air and makes it heavy to hold more particulate matters.”

The air quality in the city had turned “severe” on Monday evening, with the and the Air Quality Index touching 407 at 8 pm.

The Supreme Court-appointed Environment Pollution Control Authority on Monday said it would consider imposing a complete ban on vehicles, both private and commercial, not running on compressed natural gas if the air quality continues to worsen.

“In the scenario that the weather remains adverse and that the current situation of air quality remains in ‘very poor’ or ‘severe’ category, then there is no option but to direct for a complete stop on the use of private and commercial vehicles other than those plying on CNG so that pollution can be contained,” Environment Pollution Control Authority chairperson Bhure Lal said in a letter.

Delhi Environment Minister Imran Hussain on Monday also reviewed the action taken by various authorities in implementing the Graded Response Action Plan, the Hindustan Times reported. The minister, observing that local polluting factors such as burning and dust needed to be controlled, ordered the municipal corporations to intensify mechanical sweeping of roads.