Air quality in Delhi moved from the 'severe' to 'very poor' category after slightly improved weather conditions marginally favoured dispersion of pollutants. According to the Central Pollution Control Board (CPCB) data, 21 areas recorded severe pollution, while 13 areas saw 'very poor' air quality.
The overall PM 2.5 level -- fine particulate matter in the air with a diameter of less than 2.5 micrometer -- was recorded at 249 and the PM10 level at 378, the CPCB said.
Delhi recorded its second highest pollution level of the year on Sunday with an AQI of 450. The air quality remained 'severe' on Monday and Tuesday before moving to 'very poor' category on Wednesday morning.
According to the Indian Institute of Tropical Meteorology (IITM), air quality is likely to improve as the meteorological conditions like wind speed and ventilation index are marginally favourable for dispersion of pollutants.
Ventilation index is the speed at which pollutants can get dispersed. A ventilation index lower than 6000 sqm/second, with average wind speed less than 10 kmph, is unfavourable for dispersion of pollutants.
The index was 5500 sqm/second on Wednesday, the IITM said.
In view of prevalence of severe pollution in the national capital, industrial activities in pollution hotspots of Wazirpur, Mundka, Narela, Bawana, Sahibabad and Faridabad, and construction work across Delhi-NCR was ordered to remain shut till Wednesday.
In a letter to Delhi Chief Secretary Vijay Kumar Dev, EPCA Chairperson Bhure Lal directed him to ban all construction activities in the national capital, Faridabad, Gurugram, Ghaziabad and Noida till Wednesday.
The EPCA directed the traffic police to deploy special teams and ensure congestion-free traffic flow particularly in identified high-traffic corridors. The agencies concerned have also been asked to ensure strict action against illegal industries, intensify ground action and make all efforts to control polluting activities, particularly waste burning.