Delhi's air quality was in the 'very poor' category on Sunday, but set to worsen after Diwali celebrations in the evening.
The average Air Quality Index (AQI) for the day settled at 376 in the 'very poor' category as a thick layer of smog enveloped the city and reduced visibility.
The air quality is forecast to turn 'severe' on Monday following Diwali celebrations, combined with vehicular emissions, as well as the peak stubble-burning season.
Of the 59 monitoring stations that recorded data on Sunday, air quality was in the 'severe' category at 12 and in the 'very poor' category at 22. The worst AQI was recorded in Jahangirpuri at 463.
The city's average AQI increased from 369 on Saturday to 376 on Sunday, remaining not far from the 'severe' threshold of 400.
Several monitoring stations have already breached this mark, indicating deterioration in air quality across the capital.
According to the Air Quality Early Warning System (EWS) for Delhi, the air quality is likely to remain in the 'severe' category from November 9 for a few days.
As per the Central Pollution Control Board (CPCB), an AQI between 0 and 50 is classified as 'good', 51 and 100 as 'satisfactory', 101 and 200 as 'moderate', 201 and 300 as 'poor', 301 and 400 as 'very poor', and 401 and 500 as 'severe'.
Weather and air quality experts have attributed the anticipated deterioration to unfavourable meteorological conditions, the onset of Diwali-related celebrations and vehicular emissions, along with the peak period of stubble burning in neighbouring states.
Unfavourable meteorological conditions are further aggravating the situation.
According to the EWS, a ventilation index below 6,000 square metres per second, coupled with an average wind speed of less than 10 kilometres per hour, is unfavourable for the effective dispersion of pollutants. PM2.5 was the predominant pollutant in the national capital on Sunday, with emissions from firecrackers adding to the levels of particulate matter.
According to the Decision Support System (DSS) for Delhi, the transport sector is set to be the largest contributor to the city's pollution on Sunday, accounting for 19 per cent.
Stubble burning is set to contribute 3.5 per cent, with forecasts suggesting that the contribution might remain around 2.99 per cent on Monday.
With Stage III restrictions already in force, additional pollution-control measures are being implemented alongside the existing restrictions. The emergency action plan covers Delhi and adjoining districts in Haryana, Uttar Pradesh and Rajasthan.
GRAP is a four-stage emergency framework implemented by the CAQM in coordination with the CPCB and state governments. The stages are activated based on pollution levels and forecasts from the India Meteorological Department (IMD) and the Indian Institute of Tropical Meteorology (IITM), allowing authorities to introduce restrictions before air quality deteriorates further.
Stage I is triggered when the AQI falls in the poor category (201-300), with measures focusing on road dust control, enforcement of pollution norms and a ban on open waste burning. Stage II, applicable to the very poor category (301-400), brings enhanced dust-control measures, higher parking fees and staggered office timings.
Stage III applies when the AQI is in the 401-450 range and includes restrictions on certain vehicles, a halt to non-essential construction activities and hybrid learning arrangements for primary school students. Stage IV, meant for the severe-plus category when the AQI exceeds 450, provides for restrictions on heavy goods vehicles and additional emergency measures targeting traffic and industrial pollution.
Under the Stage III restrictions, BS-III petrol and BS-IV diesel four-wheelers are barred from plying in Delhi and designated districts of the NCR. Restrictions have also been tightened on older light and medium goods vehicles and diesel commercial vehicles not registered in Delhi entering the capital.
Non-essential construction activities that generate substantial dust have been suspended. These include major excavation and earthwork, demolition and road construction. Essential projects allowed to continue must adhere to stringent dust-mitigation measures. Stone crushers and mining operations, which generate significant amounts of dust, are also subject to shutdowns or operational restrictions.
The measures are aimed at containing pollution across Delhi-NCR as the region enters the Diwali period, when concerns over a further deterioration in air quality remain high.
(With inputs from ANI)