Delhi's air quality likely to enter severe’ category due to Diwali, stubble burning, says study

New Delhi: Delhi’s air quality is likely to enter the ‘severe’ zone on Diwali night and the share of stubble burning in its PM2.5 pollution may go up to 40 per cent the day after, according to the Ministry of Earth Sciences’ air quality forecast agency SAFAR. Under the zero firecracker emission scenario, Delhi’s PM2.5 concentration is predicted to be in the upper end of the ‘very poor’ category from November 4 to November 6. “However, even if we consider 50 per cent of firecracker-related emissions of 2019, the AQI is predicted to degrade to the ‘severe’ category from November 4 night and will remain so till November 5,” SAFAR said. The PM2.5 concentration in the national capital can surpass 300 micrograms per cubic metre on November 5. The safe limit is 60 micrograms per cubic metre. The contribution of farm fires in Delhi’s air pollution has remained low this season so far due to the record-breaking rainfall in October and “unfavourable” wind direction. However, it is likely to go up to 40 per cent by November 5 as the wind direction is expected to change northwesterly after Diwali, said Gufran Beig, the founder project director of SAFAR. Northwesterly winds carry smoke from farm fires in Punjab and Haryana towards the national capital. Farm fires accounted for six per cent of the PM2.5 pollution in the national capital on Tuesday. The contribution will remain marginal (less than 10 per cent) until November 3 despite a higher fire count due to unfavourable wind direction, SAFAR said. “Stubble fire share in Delhi’s PM2.5 is predicted to be 20 per cent to 40 per cent during November 4-6,” SAFAR said adding the peak could be recorded on November 5 if the fire counts are assumed to be 4,000 as expected. Last year, the share of stubble burning in Delhi’s pollution had peaked at 42 per cent on November 5. In 2019, crop residue burning accounted for 44 percent of Delhi’s PM2.5 pollution on November 1. The air quality in the national capital entered the very ‘poor’ category for the first time this season on Tuesday owing to unfavourable conditions for dispersion of pollutants, authorities said. Stubble burning accounted for six per cent of the PM2.5 pollution in Delhi on Tuesday. The rest of the pollution is due to local sources, Beig said. According to the Central Pollution Control Board, the capital recorded a 24-hour average air quality index (AQI) of 303. It was 281 on Monday, 289 on Sunday and 268 on Saturday. The neighbouring cities of Faridabad (306), Ghaziabad (334) and Noida (303) also recorded very poor air quality. 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’.