Delhi’s air quality plummeted on the Diwali day, hitting the "very poor" category with an air quality index. (File)Delhi’s air quality plummeted on the Diwali day, hitting the “very poor” category with an air quality index (AQI) of 312.
This is the first “very poor” air day of the season for the national capital. Gurgaon and Noida also recorded air quality in the “very poor” category, with respective AQIs of 322 and 305. An AQI between 301 and 400 is considered to be “very poor” and can cause respiratory illness on prolonged exposure, according to the Central Pollution Control Board.
On Sunday, Delhi’s AQI was 259, in the “poor” category.
According to the SAFAR forecasting system, the AQI is likely to hit the upper end of the “very poor” category or the lower end of the “severe” category on Monday night on account of firecracker emissions and the impact of crop-residue burning. The impact of stubble burning on Delhi’s air is likely to be low to moderate and with ventilation being low, conditions are not favourable for the dispersion of pollutants.
The contribution of stubble burning to PM2.5 levels in Delhi could increase further to around 10 per cent owing to favourable winds, according to the forecast. The number of instances of crop-residue burning recorded on Monday was 1,019 in Punjab and 250 in Haryana, going by data from the Indian Agricultural Research Institute.
All monitoring stations in the city recorded 24-hour average AQI in the “poor” or “very poor” categories at 6pm on Monday, with PM2.5 being the prominent pollutant at most stations.