Delhi's air quality deteriorated further today with six areas in the city recording 'severe' pollution as authorities predicted further rise in the next two days.
The Central Pollution Control Board (CPCB) recorded an overall air quality index (AQI) of 352, which falls in the "very poor" category.
An AQI between 0 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 is considered to be "severe".
Six areas -- Ashok Vihar, Anand Vihar, Burari, Mundaka, Nehru Nagar and Wazirpur -- recorded severe air quality, according to the CPCB.
Twenty-five areas of the national capital recorded "very poor" air quality, while in four areas it was in the "poor" category, it said.
The PM2.5 (fine particulate matter in the air with a diameter of less than 2.5 micrometre) level was recorded at 208 and the PM10 level at 397, it added.
Ghaziabad recorded severe pollution level at 404 while Faridabad and Noida recorded "very poor" air quality, according to the CPCB data.
In Gurgaon, the air quality was "poor", it said.
The Centre-run System of Air Quality and Weather Forecasting (SAFAR) said the air quality index dropped speedily as expected, but remained "very poor".
"Although increasing-AQI trend is predicted from tonight (Tuesday night) for the next two days, it will remain in 'very poor' range only. This is mainly due to decline in wind speed along with adverse meteorological conditions. The contribution from long-range dust or stubble biomass is negligible," SAFAR said.
According to the Indian Institute of Tropical Meteorology (IITM), the maximum ventilation index is likely to be 3,500 sqm/second on Tuesday.
A ventilation index lower than 6,000 sqm/second with average wind speed less than 10 kmph is unfavourable for dispersion of pollutants, the IITM said.
Delhi's air quality has been in the "very poor" category for the past one week but on Saturday it had improved to "poor" category for a brief period. It again slipped into "very poor" category Sunday, the authorities said.
Delhi's Maximum Temperature Settles At 38.4 Degrees, Rain Likely Tomorrow Delhi Pollution Under Control Centres Shut Amid Protest Over Fee Hike Delhi Government Increases PUC Certificate Fees For The First Time In 13 Years World's Largest Isolated Tribe Makes Rare Appearance In New Footage Barack Obama Wants Joe Biden To Pull Out Of US Presidential Race: Report Why BJP Lost Lok Sabha Polls In Uttar Pradesh - 6 Reasons In Party Report Comedy Legend Bob Newhart Dead At 94: Publicist Israeli Strike Kills Field Commander In Elite Hezbollah Unit: Report Delhi-San Francisco Air India Flight Diverted To Russia After Engine Glitch Track Latest News Live on NDTV.com and get news updates from India and around the world.