This story is from November 17, 2019

Delhi breathes easy, has cleanest air in 1 week

After choking on toxic air for four consecutive days, the capital on Saturday woke up to welcome sunshine and strong wind, which helped clean up the air by flushing out accumulated pollutants. The fall in the number of stubble fires in the neighbouring states also helped. The AQI was recorded at 357 (very poor) which was better than Friday’s 458 (severe).
Delhi breathes easy, has the cleanest air in 1 week
Key Highlights
  • The air quality index (AQI) was recorded at 357, still a ‘very poor’ level, but a marked improvement from Friday’s 458 (‘severe’)
  • Neighbouring NCR towns of Faridabad (358), Ghaziabad (347), Greater Noida (309), Gurgaon (360) and Noida (338), too, saw appreciable decline in pollution levels
NEW DELHI: After choking on toxic air for four consecutive days, the capital on Saturday woke up to welcome sunshine and a strong wind, which helped clean up the air by flushing out accumulated pollutants. The fall in the number of stubble fires in the neighbouring states also helped.
The air quality index (AQI) was recorded at 357, still a ‘very poor’ level, but a marked improvement from Friday’s 458 (‘severe’).
This was also the best air quality the city had witnessed in the past seven days. The previous best was on November 10 when the AQI was at 321.
Neighbouring NCR towns of Faridabad (358), Ghaziabad (347), Greater Noida (309), Gurgaon (360) and Noida (338), too, saw appreciable decline in pollution levels.
The air, however, will get fouler again from November 20, Wednesday, MeT predictions say.
The 24-hour average PM2.5 and PM10 readings which was at ‘severe plus’ levels and five times above the safe standards on Friday, according to CPCB’s central control room data, improved quite a bit over the past day. While Delhi-NCR’s average PM2.5 was 364.7 micrograms per cubic metre at 7pm on Friday, on Saturday it nearly halved and touched 175 at 7pm. The average PM10 concentration, which was 506.8 micrograms per cubic metre at 7pm on Friday, reached 301.9 in 24 hours. The ‘emergency’ benchmark for these pollutants under the graded response action plan is, respectively, 300 and 500 micrograms per cubic metre while the safe standards are 60 and 100 micrograms per cubic metre.

According to SAFAR, under the influence of western disturbance, strong boundary layer and surface winds are flushing out the accumulated pollutants. “The effective stubble fire count is low. Even if it is high, transport-level wind direction is not favourable (northerly), and the speed is so high (42 km per hour) that the stubble plume will surpass Delhi and complete its lifespan before it touches the bottom end of the Indo-Gangetic plains (Mathura-Agra),” a SAFAR official said.
The accumulated stubble impact from Delhi’s air is also getting flushed out and Sunday’s stubble share in Delhi’s PM2.5 is predicted to be not more than 2%, a report stated.
“Sufficient sunshine and strong surface winds, which went up to 25 kilometres per hour, in the region cleared out the smog and helped disperse the trapped pollutants. Windy conditions are expected on Sunday and Monday as well and the air quality will improve further in the next two days,” a senior MeT official told TOI, adding that from November 19 onwards wind speed might decline, again.
In terms of weather, on Sunday, mainly clear sky with strong surface winds during the day time is expected. The maximum and minimum temperatures would be around 28 and 16 degree Celsius respectively.
The maximum and minimum temperatures on Saturday were 29.3, one degree Celsius above normal, and 15.4, two notches above normal. Humidity levels oscillated between 84 and 55%.
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