On Sunday, 30 areas of the national capital recorded 'severe' air quality.

Delhi recorded its second highest pollution level of the year on Sunday and unfavourable meteorological conditions are likely to keep the air quality in the 'severe' category for the next couple of days, the authorities said.

While the Central Pollution Control Board (CPCB) data showed the overall air quality index (AQI) at 'severe' level of 446, the Centre-run System of Air Quality and Weather Forecasting (SAFAR) showed a higher level at 471.

This is the second highest pollution level of this year. The highest was recorded on November 8, a day after Diwali, when the AQI touched 571.

An AQI between 100 to 200 comes under the 'moderate' category, 201 and 300 is considered 'poor', 301 and 400 'very poor', while that between 401 and 500 is 'severe'.

According to experts, under the 'severe' category, even healthy people find it hard to breathe and doctors advise physical activity to be kept at a minimum.

The CPCB-led task force, during a meeting on Saturday, recommended minimising outdoor exposure for the next couple of days and avoiding use of private vehicles.

On Sunday, 30 areas of the national capital recorded 'severe' air quality while it was 'very poor' in six, the CPCB said.

Several areas like Ashok Vihar, Anand Vihar and Wazirpur, among others, inched towards the 'severe plus emergency' category, the data showed.

In NCR, Ghaziabad recorded the worst air quality with an AQI of 473. Faridabad and Noida also recorded 'severe' air quality, the CPCB said.

In Delhi, the overall PM2.5 level -- fine particulate matter in the air with a diameter of less than 2.5 micrometer -- was recorded at 402 and the PM10 level at 580, the CPCB said.

The India Meteorological Department (IMD) said prolonged period of light winds and low temperature are likely to continue for next three to five days, resulting in poor dispersion of pollutants and the air quality may continue to remain in the 'severe' category for the next two to three days.

Officials said they are closely monitoring the situation and if these conditions persist for 48 hours, then stringent action would be taken.

Stringent action includes emergency measures like car rationing and a ban on construction activities.