Air pollution levels in Delhi worsened on Friday morning due to unfavourable meteorological conditions -- low temperature and slow wind speed -- and the air quality index read 403 at 9 am, which falls in the severe category.
Low temperatures and slow surface winds allow accumulation of pollutants.
The city's 24-hour average air quality index (AQI) read 400 on Thursday evening.
The air quality in the capital has remained very poor or severe on most of the days in November so far.
Delhi recorded lowest air pollution levels -- in terms of 24-hour average quality index -- on November 1 (AQI 281) followed by November 23 (AQI 290).
Neighbouring Faridabad (417), Ghaziabad (373), Greater Noida (378), Gurgaon (361) and Noida (383) also saw a dip in air quality on Friday morning.
An AQI between zero 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 severe.
Delhi recorded a minimum temperature of 11 degrees Celsius. The maximum temperature is likely to settle around 28 degrees Celsius.
According to the Ministry of Earth Sciences' air quality monitor SAFAR, no relief is likely till Monday.
Local emissions and weather are likely to be the dominant factors controlling air quality, it said.
The Delhi government on Thursday reimposed the ban on construction and demolition activities following the Supreme Court order in this regard.
The apex court reimposed the ban on construction activities in Delhi-NCR on Wednesday until further orders.
Chief Minister Arvind Kejriwal said the workers affected by the ban on construction activities in the national capital will be provided a financial assistance of Rs 5,000 each and his government will also compensate them for the loss of minimum wages.
The ban on construction and demolition activities was lifted on Monday in view of an improvement in the air quality and the inconvenience caused to the workers.
The Delhi government had on Wednesday decided to resume physical classes in schools, colleges and other educational institutions and reopen government offices from November 29.
The ban on the entry of trucks, barring those engaged in essential services, will continue till December 3.
However, 'CNG and electric trucks will be allowed to enter Delhi from November 27'.
On November 13, the city government had ordered the closure of all educational institutes, banned construction and demolition activities and asked its employees to work from home to combat air pollution and minimise its health effects.
Four days later, it extended the restrictions, besides banning the entry of trucks carrying non-essential items in Delhi.
