new delhi: Delhi's air quality slipped back into the "very poor" category again on Tuesday after recording a marginal improvement a day ago. However, the share of stubble burning in Delhi's pollution dropped to 10 per cent during the day due to a change in the wind direction, a central government agency said.
Officials at the India Meteorological Department said the air quality had improved on Monday with high wind speed aiding the dispersion of pollutants. However, stagnant night-time conditions led to the accumulation of pollutants.
The city recorded an air quality index (AQI) of 332 at 10 am. It improved to 302 by 4 pm as wind speed picked up. The 24-hour average AQI was 293 on Monday which falls in the "poor" category. It was 364 on Sunday, with stubble burning contributing to 40 per cent of Delhi's pollution.
The Ministry of Earth Sciences' air quality monitor, SAFAR, said the share of stubble burning in Delhi's PM 2.5 pollution has "decreased significantly" due to a change in the wind direction and is estimated at 10 per cent for Tuesday. It said 3,068 farm fires were spotted over Punjab, Haryana, Uttar Pradesh and Uttarakhand
on Monday.
The boundary layer wind direction became southwesterly on Tuesday morning after a long spell which is unfavourable for the transport of pollutants from farm fires in Punjab and Haryana, according to the agency.
SAFAR said it was a typical example of high fire count and its low impact on Delhi's air quality due to unfavourable transport-level winds, "demonstrating how meteorology can play a decisive role". Stubble burning accounted for 16 per cent of Delhi's pollution on Monday and 40 per cent on Sunday, the maximum so far this
season.
SAFAR has predicted a marginal deterioration in the air quality on Wednesday and Thursday. According to the India Meteorological Department, the maximum wind speed was 12 kilometers per hour on
Tuesday.