As air quality turned severe again in the national capital, Delhi Environment Minister Gopal Rai on Friday directed agencies and departments concerned to ensure strict implementation of curbs on polluting vehicles and check the increasing incidents of biomass burning.

Recent data shows that vehicular emissions account for about 25-30 per cent of the capital's air pollution. Though stubble burning has reduced, biomass burning at different locations in Delhi-NCR is responsible for 21 per cent of Delhi air pollution, Rai told reporters here.

Earlier during the day, Rai chaired a meeting with senior officials of various departments to review the air pollution situation.

He said the transport department and the Delhi Traffic Police have been asked to strictly monitor the implementation of curbs on BS III petrol and BS IV diesel vehicles under stage III of the Centre's air pollution control plan called the Graded Response Action Plan.

The Municipal Corporation of Delhi and the revenue department have been instructed to check the incidents of biomass burning.

"Such cases are only going to increase as temperatures dip in the coming days," Rai said.

The minister said air pollution levels will remain hazardous for two days and thereafter, slight relief is expected due to anticipated favourable meteorological conditions.

Air quality in Delhi turned severe again on Friday, with a dip in temperatures and slow wind speed at night allowing the accumulation of pollutants.

The city's Air Quality Index (AQI) stood at 401 at 8 am. Delhi has been witnessing a gradual increase in AQI levels after a marginal improvement on Sunday.

The 24-hour average AQI, recorded at 4 pm every day, was 390 on Thursday, 394 on Wednesday, 365 on Tuesday, 348 on Monday and 301 on Sunday.

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