A ban on construction activities came into force in the national capital Thursday as Delhi's air quality was on the brink of turning "severe" due to stubble burning in the adjoining regions and unfavourable meteorological conditions, authorities said.

The overall air quality index (AQI) of Delhi was recorded at 393, which falls in the  "very poor" category and is just seven points from turning severe, according to data by the Central Pollution Control Board (CPCB).

Gurgaon, Faridabad and Noida recorded an AQI of 416, which falls in the "severe" category, while air quality was "very poor" in Ghaziabad and Greater Noida.

Eleven areas in Delhi recorded "severe" air quality while 16 areas recorded "very poor" air quality, according to the CPCB data.

The PM2.5 level was recorded at 217. Fine particulates can be a matter of more serious health concern than PM10 (particles in the air with a diameter of less than 10 micrometres).

As per the CPCB data, the PM10 level in Delhi stood at 368.

The Centre-run System of Air Quality Forecasting And Research (SAFAR) said the AQI of Delhi-NCR would continue to remain in the upper range of the "very poor" category in the next three days.

"This is mainly due to weather conditions as stubble contribution is marginal now. The moisture intrusion over Delhi and surrounding regions due to the westerlies disturbances will increase with effect from November 4 to enhanced holding capacity of atmosphere resulting in increase in PM2.5 levels," the SAFAR website said.

"Winds are calm and it is favourable for stagnation of pollution. Although upper air winds where transport takes place are from stubble burning site but speed and magnitude is low and hence unlikely to impact Delhi air quality significantly," it added.

According to the SAFAR, 12 per cent of PM2.5 pollution in Delhi is caused due to stubble burning.

As the air quality of the national capital deteriorated, a ban on construction activities was imposed on Thursday for 10 days to prevent dust from adding to the pollution levels.

There is a halt on all construction activities involving excavation. Civil construction has also been suspended in Delhi and other NCR districts, besides closure of all stone crushers and hot mix plants generating dust pollution.

The Delhi Pollution Control Committee has also directed the transport department and the traffic police to intensify checking of polluting vehicles and control travel congestion in the region during November 1-10.