New Delhi | Early morning visibility was low in parts of the national capital on Friday due to a thick layer of smog and haze, with mercury levels settling at 9 degree Celsius.

Delhi's air remained in the 'very poor' category, with the 24-hour average Air Quality Index (AQI) settling at 382, edging closer to the 'severe' category.

According to the Central Pollution Control Board's SAMEER app, out of 40 air quality monitoring stations across the city, 14 recorded severe air quality while 26 were in the very poor category. Vivek Vihar recorded the worst air quality with an AQI of 434, the data showed.

As per the Central Pollution Control Board's classification, an AQI between zero and 50 is considered good, 51 to 100 satisfactory, 101 to 200 moderate, 201 to 300 poor, 301 to 400 very poor and 401 to 500 severe.

The Air Quality Early Warning System for Delhi has forecast that air quality is likely to remain in the 'very poor' category till Saturday and deteriorate to 'severe' on Sunday.

Several parts of the national capital were seen enveloped in dense smog during the early morning hours, leading to reduced visibility.

According to the India Meteorological Department, the minimum temperature settled at 9 degrees Celsius, while relative humidity stood at 100 per cent.

The maximum temperature is expected to hover around 21 degrees Celsius, with dense fog likely to persist through the day.

Meanwhile, the ban on the entry of non-Delhi private vehicles below BS-VI emission standards and enforcement of the 'No PUC, No Fuel' rule came into force in the national capital on Thursday as authorities stepped up measures to tackle worsening air pollution.

Fuel pumps are not dispensing fuel to vehicles without valid Pollution Under Control (PUC) certificates, with enforcement being carried out using automatic number plate reader cameras, voice alerts at fuel stations and police support.