Pollution levels in India's capital remained two times above the severe level yesterday, in what is the most polluted summer in recent years, forcing the authorities to take emergency measures, including shutting down all construction activities.
Pollution was hovering at more than three times the severe level for a number of days before dipping yesterday afternoon, but air quality was still well into the "severe" category.
Levels of PM10, or coarse dust particulate matter less than 10 micrometres in diameter, rose to 1,500 micrograms per cubic metre on average over the past two days in Delhi and satellite cities Gurugram and Noida. The severe level starts at 430 micrograms per cubic metre.
Meteorologists said dust storms in nearby desert areas had brought dust particles into Delhi. Combined with the existing pollutants in the air, this has resulted in smog-like conditions and a deterioration in the air quality.
"It is unusual for it to be so severe during the summer months.
"This time, the average was 1,500 micrograms per cubic metre. We haven't seen this in the last eight years at least," said Dr Gufran Beig, chief scientist at India's state-run System of Air Quality Weather Forecasting and Research, which comes under the Ministry of Earth Sciences.
The authorities have implemented emergency measures, even ordering the sprinkling of water on roads to settle the dust and keeping a strict vigil on the burning of municipal waste.
There was also an increase in the use of machinery to clean the roads, and construction activities have been ordered to stop until tomorrow.
The Indian Meteorological Department has predicted improved air quality by today. By yesterday afternoon, pollution levels had come down but they were still registering at two times over the severe limit.
Once the world's most polluted city, Delhi remains on the World Health Organisation's list of cities struggling to cope with pollution.
The city has a population of 16 million people and over 10 million vehicles, with many households owning multiple cars.
Constant construction works around Delhi, a preference for diesel cars and the burning of crop stubble by farmers have all contributed to the deteriorating air quality. This has resulted in pollution levels doubling over the last decade.
With pollution levels remaining above the severe level, the authorities have asked residents to remain indoors as much as possible.
"We need massive dust control measures starting from very strict control over construction activities to massive greening efforts. We need to create a green wall to create a dust barrier.
"Dust in its pristine form is a respiratory irritant. But by the time dust enters the urban environment, it is coated in toxic elements and you end up inhaling all this toxic material," said Ms Anumita Roychowdhury, executive director at the Centre for Science and Environment.
With Delhi and its satellite cities recording regular spikes in pollution levels, the public has been piling on the pressure to get the government to do more.
Army veteran Ashok Kumar Singh, a former colonel, said his health has been affected and he now suffers from respiratory problems.
"Pollution can't be resolved overnight. You need to have a 10-to 15-year plan. That plan is not there," said Mr Singh. "After settling down here, I have become sick. I was a fit guy in the army and took part in military operations.
"The enemy couldn't kill me but pollution is."