Overall air quality index is expected to enter the "severe" category for a short period on Sunday night.
Delhi's air quality remained "very poor" today and is expected to turn "severe" post-Diwali due to firecracker emissions and spike in stubble burning in neighbouring states.
According to the System of Air Quality and Weather Forecasting and Research (SAFAR), the National Capital Region's overall air quality index (AQI) is expected to enter the "severe" category for a short period of time on Sunday night, but the situation would be not as bad as last year.
Last year, Delhi's AQI stood at 642, which falls in the "severe plus emergency" category, on November 8, the day after Diwali. In 2017, the AQI post-Diwali was 367.
With air quality plummeting to dangerous levels around Diwali every year, the Supreme Court last year banned polluting firecrackers and ordered that only green firecrackers, which is said to cause 30 per cent less pollution, can be manufactured and sold.
But the green pyrotechnics have failed to draw good response both from sellers and buyers, primarily due to lack of variety, limited stock and high prices.
The SAFAR said the highest impact of firecracker emissions was expected early on Sunday from 1-6 am.
"If 50 per cent of the total load of firecrackers (average of Diwali 2017 and 2018) is added, the AQI may plunge to the severe category for a short period," it said, adding that the situation would be not as bad as last year.
The SAFAR said Delhi's overall air quality today, 302, is in the lower end of the "very poor" category.
An AQI between 0-50 is considered "good", 51-100 "satisfactory", 101-200 "moderate", 201-300 "poor", 301-400 "very poor", and 401-500 "severe". Above 500 is "severe-plus emergency" category.
The SAFAR said stubble burning incidents in Haryana and Punjab were increasing gradually and following almost the same pattern as that of last October. Surface and boundary layer wind direction is likely to change to northwesterly. As a result, the share of stubble burning in Delhi PM2.5 concentration might increase to 25 per cent in the upcoming days, it said.
On Sunday, the share of smoke from crop residue burning in the city's PM2.5 concentration is predicted to be 19 per cent.
Apprehending a dip in air quality post Diwali due to firecracker emissions, stubble burning and unfavourable weather, the Supreme Court-mandated Environment Pollution (Prevention and Control) Authority on Friday banned construction activities at night in the NCR from Saturday-Wednesday.
It also directed closure of coal-based industries, barring power plants, in Faridabad, Gurgaon, Ghaziabad, Noida, Greater Noida, Sonepat and Bahadurgarh during the period.
On EPCA's direction, the Delhi Pollution Control Committee (DPCC) have also ordered the closure of industries, which have not yet shifted to piped natural gas, from Saturday-Wednesday.
A PMO-led panel has directed implementing agencies and the NCR states to intensify anti-pollution measures up to mid-November so that there is immediate impact on air quality. The Centre has also asked Haryana and Punjab to stop stubble burning completely for the next few "critical" days.