Delhi’s air quality slipped to the ‘poor’ category on Saturday. With an increase in the impact of stubble burning on air quality in the national capital, PM2.5 levels have also risen.
The Central Pollution Control Board’s AQI bulletin released at 4 pm on Saturday indicated that Delhi’s AQI stood at 284, with PM10 and PM2.5 as the main pollutants. The figure is an average of AQI over the past 24 hours from the CPCB’s 36 monitoring stations. According to the National Air Quality Index, AQI between 201 and 300 is categorised as ‘poor.’
In terms of health impact, the CPCB categorises ‘poor’ AQI as causing “breathing discomfort to most people on prolonged exposure”.
The System of Air Quality and Weather Forecasting and Research (SAFAR) under the Union Ministry of Earth Science and the Indian Institute of Tropical Meteorology, Pune, said in an update on Saturday that the impact of stubble burning on Delhi’s air quality was ‘high.’
The contribution of stubble burning to PM2.5 levels in Delhi has grown to 14%, the highest so far for this season. This figure had remained below 5% so far, SAFAR data indicates.
PM2.5 was the lead pollutant at these two stations as well. Till Friday, SAFAR updates had indicated that PM10 was the lead pollutant, mostly due to resuspension of dust.
According to the SAFAR update on Saturday, meteorological conditions favoured the intrusion of stubble burning-related air mass into Delhi. Winds coming from the northwest direction were favourable for this intrusion. The wind direction, however, is likely to shift to the easterly direction on Sunday, and rainfall is likely. The AQI is likely to remain in the ‘poor’ category on Sunday, but could improve and move into the ‘moderate’ category for the three days after that, the update said. A PM2.5 level of 125 micrograms per cubic metre on Saturday is likely to rise to 138 micrograms per cubic metre on Sunday, according to the SAFAR forecast.
Over the past few days, the national capital’s air quality has been falling steadily, but the AQI has so far remained within the ‘moderate’ category, which lies between 100 and 200. On October 15, the AQI stood at 198, while on October 14, it stood at 182, a few notches above 171 on October 13. On October 12, the AQI was at 179, while October 11 saw an AQI of 166, and on October 10 it stood at 168. On October 9, the AQI was marginally higher at 171.
The NASA Fire Information for Resource Management System (FIRMS) that maps fire spots showed denser clusters of fire spots in Punjab and Haryana on October 16 as compared to October 12.
There were 1,572 “active effective” fire counts as of Friday, which were likely to impact Delhi’s air on Saturday, according to Gufran Beig, founder project director, SAFAR. The SAFAR data on fire counts is obtained from two ISRO satellites.
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