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Saturday, September 19, 2020

Farm fires rise, air quality dips as Delhi holds its breath again

Strong winds disperse pollution but bring fresh pollutants from Northwest.

By: Express News Service | New Delhi | Updated: October 30, 2019 8:14:00 am
Vanishing Act: Seen from Raisina Hill, the India Gate was barely visible through the haze Tuesday. (Express Photo by Krishn Kaushik)

Delhi’s air quality oscillated between ‘very poor’ and ‘severe’ in the past 24 hours, with stronger wind speed aiding dispersion of accumulated pollution load but also bringing in fresh pollutants from the Northwestern part of the country.

Haze dominated the day as the Air Quality Index (AQI) at 4 pm was recorded at 400 (very poor). On Monday, the AQI value at the same time was 368 but deteriorated and crossed the 400 mark late evening, turning the air ‘severely’ polluted.

On Tuesday, too, the AQI later in the evening was 410. By late night, pollution had climbed further with the AQI touching 422.

Authorities in Delhi have been directed to undertake several steps, including sprinkling of water to control dust, diesel genset ban, and a ban on open burning to control emissions.

According to the System of Air Quality and Weather Forecasting And Research (SAFAR) forecast, a relative decrease in the concentration of particulate matter (PM) is expected on Wednesday and Thursday.

“With changing weather conditions, PM concentration will decrease and the air quality index (AQI) will be in the very ‘poor’ range. One of the reasons that Diwali-related pollution was not as high as the last few years was that the festival was on an earlier date than usual. With crop stubble burning at its peak, air quality is not expected to improve significantly, though,” said a SAFAR official.

Other SAFAR officials reiterated that the major reason behind the dip is the increase in crop stubble burning in Punjab and Haryana.

“As of today, the stubble plume from Northwest regions has become one of the significant factors in deteriorating Delhi’s air quality. As evident from SAFAR-multi-satellite fire product, effective stubble fire counts of Haryana and Punjab have increased from 1,654 to 2,577 during the past 24 hours after showing a noticeable dip on October 27… stubble share (on pollution) may touch this year’s peak value (at around 29%) on October 30,” a statement issued by SAFAR scientists said.

A look at the National Aeronautics and Space Administration (NASA) active fire maps shows that most of the fires between Monday and Tuesday were concentrated over Punjab.

Dipping temperatures have also contributed to dipping air quality.

On Tuesday, the maximum temperature was recorded at 28.8 degrees Celsius, two degrees below normal. Low temperature, high humidity and calm winds are among key factors that determine the rate of accumulation of pollutants in the air. Tuesday’s maximum humidity was 80%.

The situation is set to relatively improve by Friday. Officials said that an increase in wind speed in the upper atmosphere is expected by Friday, which will in turn lower the AQI.

Officials at the Delhi Pollution Control Committee (DPCC) also said the impact of local dust in Delhi is minimal at present.

“So far, Delhi’s local sources of pollution — primarily vehicular pollution and dust — have not increased. Traffic has been light over the weekend because of Diwali and Bhai Dooj, and strict dust control measures are in place. We are trying to control local sources as much as possible,” said a senior DPCC official.

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