Delhi's air quality remained 'very poor' on Saturday even as authorities warned of a spike in pollution level from the next week when dense fog is expected to engulf the national capital.

The Central Pollution Control Board (CPCB) recorded an overall air quality index (AQI) of 343.

An AQI between 201 and 300 is considered 'poor', 301 and 400 'very poor' and 401 and 500 is 'severe'.

The air quality in four areas --Jahangirpuri and Nehru Nagar recorded severe air quality while 26 areas recorded very poor air quality and two areas recorded poor air quality, according to CPCB.

The overall PM2.5 (fine particulate matter in the air with a diameter of less than 2.5 micrometre) level was recorded at 193 and the PM10 level at 353, it said.

In NCR,  Faridabad and Noida recorded 'very poor' air quality, the CPCB data showed.

The Centre-run System of Air Quality and Weather Forecasting (SAFAR) said the overall air quality of Delhi continues to remain in the 'very poor' range.

"Meteorological conditions have slightly improved causing dispersion of pollutants but the air quality might deteriorate from Sunday with dense fog engulfing the capital which may degrade the air quality," the SAFAR said.

According to the Indian Institute of Tropical Meteorology, the maximum ventilation index was likely around 4000 sqm/second on Saturday.

A ventilation index lower than 6,000 sqm/second with average wind speed of less than 10 kmph is unfavourable for dispersion of pollutants, it said.

The Supreme Court-appointed Environment Pollution Control Authority Friday said they are seriously considering banning industrial, construction and demolition activities at major pollution hotspots in Delhi-NCR when air quality levels reach 'severe' category.

The Central Pollution Control Board-led task force on November 22 recommended to the EPCA that industrial, construction and demolition activities should be banned in major hotspot areas when air quality levels reach 'severe' category.

The taskforce has identified 15 pollution hotspots in Delhi. They are  Anand Vihar, Bawana, CRRI Mathura Road, DTU, Dr Karni Singh Shooting Range, Dwarka-Sector 8, Jahangirpuri, Mundka, NSIT Dwarka, Narela, Okhla Phase-2, R K Puram, Rohini, Shadipur, Wazirpur.

In NCR areas outside Delhi, six hotspots have been identified. They are -- Sector-16A in Faridabad, Vikas Sadan in Gurgaon, Vasundhara in Ghaziabad, Knowledge Park-III in Greater Noida, Sector-125 in Noida and RIICO Industrial Area-III in Bhiwadi.