Winds pull Noida and Ghaziabad out of ‘severe’ air quality

Favourable winds pulled Noida, Ghaziabad and Greater Noida out of the “severe” pollution category on Wednesday, improving the air, yet still under the “very poor”

Favourable winds pulled Noida, Ghaziabad and Greater Noida out of the “severe” pollution category on Wednesday, improving the air, yet still under the “very poor” category, which is the cleanest since November 2.

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The three cities had been breathing extremely toxic air for over a week, with its first “severe” level being recorded on on November 5.

What helped matters was the reduction in smoke from stubble burning from neighbouring Punjab and Haryana regions as the wind direction changed from north-westerly to easterly.

According to the India Meteorological Department (IMD), further improvement is likely in the next two days as the easterly winds will continue providing sufficient ventilation. A minimum wind speed of 10kmph is required to reduce pollutants in the atmosphere of the national capital region (NCR).

“The easterly winds of 10-12 kmph continued for almost the entire day on Wednesday leading to significant improvement. Since the direction of intrusion of the fire was not from Punjab and Haryana where the major fires were seen, the level of pollutants also dropped. The winds are expected to continue at the same speed for next two days, so we can anticipate a further more improvement in the region,” said Kuldeep Srivastava, head, regional weather forecasting centre, IMD.

He added that the westerly and north-westerly winds may return for some time on November 13, but is likely to shift to easterly from November 14, leading to further improvement.

“The change to westerly for some time on November 12 will not lead to significant deterioration,” added Srivastava.

According to System of Air Quality and Weather Forecasting and Research (Safar), while the stubble fire have reduced from over 4,528 on November 6 to approx. 2,422 on Wednesday there share of PM2.5 also dropped significantly in the region from over 30 per cent a day earlier to 3 per cent on Wednesday..

“The change in transport level wind direction has led to a significant decrease in the fire-related intrusion in spite of high fire counts. The PM2.5 ageing and relatively not so calm surface winds helped to flush out,” said SAFAR statement on Wednesday.

According to the central pollution control board (CPCB), the air quality index (AQI) of Noida, on a scale of 0 to 500, was 309 or ‘very-poor’ against 455 or ‘severe’ a day earlier. The AQI of Greater Noida was 340 against 436 a day earlier. The AQI of Ghaziabad was 360 against 444 a day earlier.

The average PM2.5 levels for Noida for past 24-hours was recorded to be 170 microgrammes per cubic metres (μg/m³), against 547.99μg/m³ a day earlier. For Greater Noida, the PM2.5 was 180.54μg/m³ against 536.87 μg/m³ a day earlier.

The average PM10 levels for Noida was 418.49 μg/m³ against 619.51μg/m³ a day earlier. For Greater Noida, the PM10 levels were 388.74 μg/m³ against 661.49 μg/m³ a day earlier.

According to the CPCB, the standard limit for PM10 is 100 micrograms per cubic metre (μg/m³) while the limit for PM2.5 is 60μg/m³, which are in any case much higher than the World Health Organization (WHO) limits of 20 μg/m³ and 10μg/m³, respectively.