Mask-wearing protesters took to the streets of the Indian capital as the city remained blanketed under a cloud of toxic smoke that has lingered for a week and sparked anger at the Government's slow response.

Thousands of schools have been closed, cricket matches cancelled and residents warned to stay inside as the air pollution crisis in New Delhi and the surrounding metropolitan region - deemed an "emergency situation" by the Environment Minister at the weekend - stretched into its seventh day.

Patients with breathing problems inundated hospitals and doctor's clinics, and residents waited in line to buy pricey face masks - which often sold out.

"We have never seen something like this. This time things are really bad," said P.S. Walia, 44, a father of two who was at a protest.


He has closed his house, stopped taking morning walks and kept his kids indoors this past week to protect them from the stinging air.

Experts said low winds, holiday fireworks residue and crop-burning in neighbouring states contributed to the haze, which reduced visibility at the airport to a 17-year low last week.

Air-quality data from the US Embassy's air monitor - which measures the particulate pollutant known as PM 2.5 - averaged 640, more than six times the level deemed acceptable by the Environmental Protection Agency.

Delhi's Chief Minister, Arvind Kerjiwal, said the city would undertake emergency measures to address the "need of the hour," including banning construction activity for five days, limiting diesel-generator use, water-treating dusty roads and temporarily closing a coal-fired power plant.

The city's schools will remain shut for three days, he said.

Environmental experts applauded the move but say the city - the 11th-most-polluted in the world, according to the World Health Organisation - needs far more stringent long-term solutions.

Last week, the country's environmental court had chided both the central and state governments for "shifting blame" and not taking action to address the problem.