On Saturday, the national capital recorded the season’s highest one-day fire tally with 1,230 cases of stubble burning. But in some marginal respite, the contribution of stubble burning to Delhi’s air fell to 17% on Sunday from 19% on Friday, the Ministry of Earth Sciences’ air quality monitor, SAFAR’s data revealed. Delhi’s air quality continued to be in the “poor” category on Sunday with a reading of 254 on CPCB’s Air Quality Index (AQI), however, it fared better from Saturday’s 287 poor.
Notably, an AQI between 0 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’. Data from SAFAR showed that though farm fires had gone up, a rise in the wind speed was aiding in the dispersal of pollutants and maintaining the concentration of stubble burning in the same range.
An India Meteorological Department official told news agency PTI that during the daytime, winds are blowing from the northwest, ushering in pollutants from farm fires. At night, calm winds and low temperatures are permitting the accumulation of pollutants.
According to SAFAR data, the ventilation index, a product of mixing depth and average wind speed, was 11,500 metre square per second on Sunday which is appropriate for the dispersion of pollutants. Mixing depth is the vertical height in which pollutants are suspended in the air. It goes down on cold days with calm wind speed.
Earlier on Sunday, Union Environment Minister Prakash Javadekar maintained that the pollution issue cannot be fixed in a day and consistent efforts are needed to tackle each of the contributing factors. Meanwhile, the Central Pollution Control Board (CPCB) has said meteorological conditions in Delhi have been “extremely unfavourable” for the dispersion of pollutants since September when compared to last year. With reduced area falling under non-basmati paddy cultivation this time, CPCB Member Secretary Prashant Gargava anticipated there will be fewer stubble burning cases this year as opposed to 2019.