Delhi's air quality deteriorated further and was recorded in the 'very poor' category Wednesday, with 10 areas reporting severe pollution levels as authorities said unfavourable meteorological conditions would prevail over the next few days.
The overall air quality index (AQI) of the national capital stood at 372, which falls in the 'very poor' category, the Central Pollution Control Board (CPCB) data showed.
An AQI between 100 to 200 comes under 'moderate' category, 201 and 300 is considered 'poor', 301 and 400 'very poor', while that between 401 and 500 is 'severe'.
The Centre-run System of Air Quality and Weather Forecasting (SAFAR) too said that the overall air quality of Delhi was in the 'very poor' category.
"Overall air quality of Delhi continues to be very poor. The minimum temperatures are likely to fall in Delhi (resulting in additional moisture in the air). Hence, the air quality will remain in the 'very poor' category for the next three days," the SAFAR said.
"Winds are again becoming partially favourable for the dispersion," it said.
The overall PM2.5 level (fine particulate matter in the air with a diameter of fewer than 2.5 micrometres) was recorded at 223 and the PM10 level at 359, the SAFAR said.
While Alipur, Anand Vihar, Ashok Vihar, DTU, Jahangirpuri, Mundka, Narela, Rohini, Sonia Vihar, Nehru Nagar and Wazirpur areas saw severe pollution levels, 20 places in the national capital recorded 'very poor' quality air, the CPCB said.
Neighbouring Ghaziabad, Faridabad and Noida recorded 'very poor' air quality, while in Gurgaon, it was in the 'satisfactory' category, it added.
According to the Indian Institute of Tropical Meteorology, the maximum ventilation index on Wednesday was 4,000 sqm/second.
A ventilation index lower than 6,000 sqm/second with an average wind speed of less than 10 kmph is unfavourable for dispersion of pollutants.
(With inputs from agencies.)