The national capital's air quality was on the brink of turning severe on Thursday due to stubble burning in the adjoining regions and unfavourable meteorological conditions, authorities said.
On Tuesday, Delhi's air quality slipped to severe category, prompting authorities to issue a slew of directions including ban on construction activities along with halting operations of industries using coal and biomass as fuel between November 1 and 10.
The Indian Institute of Tropical Meteorology said the prevailing meteorological conditions are less favourable for dispersal of pollutants for the next two days due to low wind speed.
Moreover, authorities said that due to pollutants caused by biomass burning in the adjoining regions of Delhi and unfavourable meteorological conditions, the air quality is likely to remain in the 'very poor' category on Thursday and Friday.
An AQI between 0 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".
The centre-run System of Air Quality Forecasting and Research said about 12 per cent of pollution by PM2.5 (presence of particles in the air with a diameter of less than 2.5 micrometres) on Thursday was caused due to stubble burning.
The PM2.5 was recorded at 235. 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).
The CPCB has on Thursday put up guidelines for the public to file complaints of air pollution in Delhi-NCR on its social media page, website, and through its mobile application.
It has also directed the pollution control bodies of Punjab, Haryana and Delhi to start criminal prosecution against agencies or individuals who do not comply with directives to check pollutant levels.
The Supreme Court-appointed Environment Pollution Control Authority (EPCA) has urged Delhiites to use public transport for the first 10 days of November to keep a check on pollution.
Noting that private vehicles contribute to 40 per cent pollution in Delhi-NCR, the EPCA urged people to reduce the use of private vehicles during this period and use public transport or other means.
(With inputs from agencies.)