Air pollution in the north of India has "reached unbearable levels," the capital Delhi's Chief Minister Arvid Kejriwal says.
Air quality in Delhi reached the "hazardous" category on Sunday.
Schools have been closed, more than 30 flights diverted and construction work halted as the city sits in a thick blanket of smog.
Mr Kejriwal called on the central government to provide relief and tackle the toxic pollution.
Levels of dangerous particles in the air - known as PM2.5 - are far higher than recommended and about seven times higher than in the Chinese capital Beijing.
Five million masks were handed out in schools on Friday as officials declared a public health emergency and Mr Kejriwal likened the city to a "gas chamber".
Mr Kejriwal's most recent comments are unlikely to please government officials, reports the BBC's South Asia regional editor Jill McGivering. She said Indian politicians were blaming each other for the conditions.