Air pollution levels in the national capital entered the 'severe' category on Tuesday, a day after the Centre's air quality panel lifted the restrictions on construction and demolition activities in Delhi-NCR.
Weather experts said 'very poor' to 'severe' air quality is likely till December 27.
The city's 24-hour average air quality index (AQI) read 402 at 4 pm, up from 332 on Monday.
Air quality in neighbouring Faridabad (395), Ghaziabad (392), Greater Noida (372), Gurugram (314) and Noida (382) was recorded in the 'very poor' category.
An AQI between zero and 50 is considered 'good', 51 and 100 'satisfactory', 101 and 200 'moderate', 201 and 300 'poor', 301 and 400 'very poor', and 401 and 500 'severe'.
The Ministry of Earth Sciences' air quality forecast agency SAFAR said low wind speed and very low temperature is leading to such conditions.
Mahesh Palawat, vice president (Meteorology and Climate Change) at Skymet Weather, said the slowing down of winds due to a western disturbance affecting northwest India and low temperature have led to the accumulation of pollutants.
The wind speed will remain low in the coming days due to two back-to-back western disturbances. Light rain is likely in the plains in north India between December 27 and December 29 which may improve the air quality a bit, he said.
On Monday, the Commission for Air Quality Management lifted the restrictions on construction and demolition activities in Delhi-NCR and the entry of trucks into the national capital in view of an improvement in air quality and a favourable meteorological forecast.
"The India Meteorological Department's forecast indicates the continuation of the favourable trend of wind speed and climatic conditions to facilitate dispersion of pollutants from the region," it had said in its order.
The central air quality panel had on Friday allowed authorities in Delhi-NCR to resume physical classes for students in Class 6 and above, colleges and other educational institutions with immediate effect.
It had also said that physical classes for students up to Class 5 can begin from December 27.
(Except for the headline, this story has not been edited by NDTV staff and is published from a syndicated feed.)
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