The Supreme Court-mandated anti-pollution authority, EPCA, on Monday asked Delhi and NCR states to step up surveillance and enforcement to check local sources of pollution and crop burning in view of a predicted dip in air quality in the next two-three days.
In a letter to the chief secretaries of Delhi, Uttar Pradesh, Punjab and Haryana, Environment Pollution (Prevention and Control) Authority Chairman Bhure Lal said hot mix plants, ready mix plants and stone crushers will continue to remain closed in Delhi-NCR.
The Supreme Court had on November 4 banned construction and demolition activities in the region till further notice.
"The air in the region has finally improved after days of dense and highly hazardous smog. This is the result of high winds and good ventilation index we have seen over the past few days," Bhure Lal said.
However, he said, the India Meteorological Department has alerted that the next few days -- from Tuesday to Thursday -- will witness slow wind speed and very little ventilation.
Under such circumstances, dispersion of pollutants will not happen and there is a likelihood that the air quality will slip back into the ''very poor'' category and even the ''severe'' category, the EPCA chief said.
The situation will worsen if there's light rain, which would be inadequate to wash away the pollutants and add to the moisture instead, he said.
"We have seen this in the past week how increased moisture, which traps the pollutants and creates a cloud of haze, leads to a sharp deterioration of air quality," the letter quoted Bhure Lal as saying.
"It is for this reason, we have to step up surveillance and enforcement (to check) local sources of pollution and crop burning, The Supreme Court has already directed all authorities to ensure tough action against pollution," he said.
The Supreme Court had on November 15 directed that hot spots be cleared of pollutants within a week.
The Ministry of Earth Sciences' air quality monitor, SAFAR, informed EPCA that the wind direction will favour intrusion of smoke from stubble burning in the next two days.
"If stubble burning is not checked, then its contribution can increase to up to 13 per cent of the PM2.5 pollutant on Tuesday," Bhure Lal said.