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Rain and winds help Delhi breathe a bit easy


Strong winds and light rains in parts of the city provided much-needed relief to Delhi residents as air quality settled at the lower end of the poor category on Monday, two days after recording the worst air quality on Diwali in recent days. five years and a period of 15 days, very bad and severe air days.

Data from the Central Pollution Control Board (CPCB) show that the general air quality index of the national capital on Monday was 221, in the poor category. By 7pm on Monday, Delhi’s AQI had reached the moderate zone, with an AQI value of 199, according to the CPCB. At least 13 of the total 38 air quality monitoring stations had AQI levels below 200.

The change was clear from the morning. At 9am on Monday, Delhi’s AQI was 300 compared to 467 at around the same time the day before.

The neighboring cities of Faridabad (256), Ghaziabad (292), Greater Noida (302), Gurgaon (314), and Noida (312) posted their AQI in the poor and very poor categories after suffering severe air quality on Saturday and Sunday.

On Sunday, a western disturbance that began to affect the western Himalayas on Saturday brought widespread and moderate rains to Delhi NCR. Delhi recorded 0.4mm of rain until 5.30pm and a wind speed of nearly 40km / h on Sunday.

After recording a severe AQI of 414 and 435 on Saturday and Sunday (Diwali and the day after Diwali), the gusty wind aided in what was the largest post-Diwali dispersal since 2015.

Unlike in previous years, when air pollution levels remain very high and fall into a severe category the day after Diwali, this time air pollution levels were gradually reduced due to favorable weather conditions, scientists from the India Meteorological Department (IMD).

VK Soni, head of IMD’s environmental monitoring research center, said that the rain coupled with the high wind speed was the reason behind the improvement in air quality observed in Delhi. “The average wind speed on Monday was around 18 km / h. The impact of Sunday’s rain and wind was also manifested in the air on Monday. For the past two days, Delhi is also receiving easterly winds, which means that the contribution from the stubble fires in Punjab and Haryana has also been negligible, ”Soni said.

Also read: Less air pollution, noise recorded in Chennai on Diwali compared to previous years

Analysis of PM2.5 level data from Delhi Pollution Control Committee (DPCC) monitoring stations shows a steady decline from midnight Monday to night. At several stations, PM2.5 levels were well below the 60 ug / m3 safety limit.

Average PM2.5 levels at 6 pm were 88ug / m3 and average PM10 levels were 135ug / m3. PM10 levels below 100 µg / m3 are considered safe in India and 500 µg / m3 is the emergency threshold. Delhi last recorded such low levels of PM10 on September 28, according to data from DPCC and CPCB.

Soni said that in the coming week, Delhi’s air is likely to remain in the moderate to poor zone. According to the IMD forecast, the wind direction is expected to change again from east to northwest on Tuesday, which could result in marginal deterioration, but because the stubble burning counts over Punjab and Haryana have now dropped, the impact on Delhi air quality will not be severe.

Rain and winds help Delhi breathe a bit easy

The air quality monitoring center of the Union Ministry of Earth Sciences, Air Quality System and Weather Forecasting and Research (Safar), showed that 282 agricultural fires were detected in Punjab and Haryana on Monday. Its impact on levels of PM 2.5 (ultrafine particles with a diameter less than 2.5 micrometers) was also only 1% on Monday.

“A change in boundary layer wind direction is forecast for tomorrow (Tuesday) afternoon, but since fire-related emissions have been reduced, no significant impact is expected. AQI is likely to improve. It is forecast to deteriorate marginally and remain in the very poor category on November 18 and November 19, ”the Safar forecast reads.

In a special report on Diwali pollution released on Sunday, the Central Pollution Control Board said that almost all pollutants reported higher values ​​on Diwali day this year compared to 2019. It could be attributed to the outbreak of firecrackers, a higher proportion of stubble burning and unfavorable weather during festival season, said the CPCB.

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