The pollution control body has declared a public healthemergency in Delhi mandated by the Supreme Court, as the region has beenstruggling with rising air pollution levels since Diwali.

The Environment Pollution (Prevention and Control) Authority has also banned construction activity till November 5 as the pollution level in the region entered the 'severe plus' or 'emergency' category late Thursday night, the first time since January.

The pollution authority has also banned the bursting of crackersduring the winter season.

Delhi Chief Minister Arvind Kejriwal on Friday described thecity as a 'gas chamber' while distributing breathing masks to school children. TheCM also blamed the neighbouring states of Haryana and Punjab, where thousandsof farmers at this time of year burn crop stubble, sending vast clouds of smokedrifting across northern India.

According to an official, if the air quality persists in the severe plus category for more than 48 hours, emergency measures such as odd-even car rationing schemes, banning entry of trucks, construction activities and shutting down schools are taken under the Graded Response Action Plan.