Delhi Environment Minister Gopal Rai will convene a high-level meeting on Friday to discuss the implementation of curbs on polluting activities under the final stage of the Graded Response Action Plan, officials said.

Delhi's 24-hour average air quality index spiralled to 450, just a notch short of the "severe plus" category as the share of stubble burning in the national capital's PM2.5 pollution soared to 38 per cent amid stagnant conditions and favourable transport-level wind speed.

As Delhi stood at the edge of a public health emergency, the Commission of Air Quality Management had on Thursday directed authorities to ban the plying of four-wheeled diesel light motor vehicles in the city and adjoining NCR districts and the entry of trucks into the national capital as part of anti-pollution measures under the final stage of the Graded Response Action Plan (GRAP).

However, BS-VI vehicles and those used for essential and emergency services are exempted, according to an order issued by the Commission for Air Quality Management (CAQM).

The order stated that the state government may take a call on the closure of educational institutions, non-emergency commercial activities and plying of vehicles on odd-even basis.

Central and state governments may decide on permitting work from home.