Pollution in Delhi after Diwali remained low: CPCB

Climate Kahani | While every year after Diwali there were concerns about air pollution, this year, compared to previous years, the country's capital saw a drop in dangerous PM 2.5 levels. Although there was a decrease in its level, but it was still above the acceptable level. But given that pollution hovers over us as a huge problem, this situation should be taken positively.

Recently, it is seen that after Diwali in the Gangetic plains in India, the sky becomes hazy and there are many difficulties in breathing. It has nothing to do with Diwali directly, but at this time many factors work together to spoil the air quality. Among these, stubble burning in neighboring states is a major reason.

An analysis of data from 33 CPCB monitors in Delhi showed that PM 2.5 levels in the capital this year were lower than in 2021, but remained above the daily safe limit of 60 ug/m3. Data for four monitors was not available, so these were excluded from the analysis. The highest level of PM 2.5 in the city was recorded at 448.8 ug/m3 in Pusa, Delhi.

This year the Air Quality Index at 8 am on October 25 was slightly higher than the same day and time last year. According to the CPCB, the average AQI of all stations in Delhi increased on the next morning of Diwali (October 25) as compared to the morning of Diwali (October 24).

The AQI of the city was 301 at 8 am on October 24. It had reached 326 at the same time on 25 October. Last year on November 4, Diwali, where the AQI for Delhi was 320. It was 317 on the morning of November 5, 2021.

According to the System for Air Quality and Weather Forecasting and Research (SAFAR), the concentration of PM 10 and PM 2.5 in the city was 257 ug/m3 and 150 ug/m3 around 10 am. Around 1.30 pm, it deteriorated to 295 ug/m3 and 189 ug/m3 respectively. According to the Central Pollution Control Board, the daily average safe limits for PM 10 and PM 2.5 are 100 ug/m3 and 60 ug/m3 respectively.

PM2.5 levels the day after Diwali

• 2021: 402 ug/m3
• 2020: 300 ug/m3
• 2019: 353 ug/m3

(Source: SAFAR)

The SAFAR data for Delhi around 1 pm on October 25 found that the overall AQI air quality for the day remained in the 'very poor' category. Fine particles (size < 2.5 µm) contribute ~64% to PM10. Last night the AQI remained in the range of 'very poor' and not 'severe'.

The share of PM2.5 emissions from fires/firecrackers in the Northwest region is ~5-6% and did not affect the air quality of Delhi much.

Local surface winds will blow at a calm speed of 8-16 km/h on the 25th, and 6 km/h (maximum temperature 31–32 °C; min 15 °C) on the 26th and 27th, leading to moderate to weak exposure to pollutants. The air quality is likely to improve further on 26th, 27th.

“It is a relatively clean Diwali week since 2015. There are four specific reasons to stay in air quality control. The first is the change in wind direction on stubble fires. Presently this direction remains North-West but yesterday it changed to South-West.

Parali not burnt in this area, hence the contribution of farm fire is minimum 5-8%. Because Diwali is always cold weather and this time it happened earlier, so the temperature is still a bit hot, and the wind speed is high, about 9 kmph."

Guffran Baig, Project Director, SAFAR

During the morning when the winds usually stabilize, it remained above 9 kmph, so ventilation was good. However, this year the number of firecrackers were also less.

Meteorologists said that the conditions are favorable to keep the pollution level under control.

“We usually see alarming levels of pollution after Diwali, but this year it has not been that bad. While crackers contribute to the air pollution of the city, the major factor is the weather. Winds and temperatures were favorable this year. In the next few days, the winds will continue to blow from the northwest and the pollution level will be low. However, it will remain in the poor or very poor category."

Mahesh Palawat, Vice President – ​​Meteorology and Climate Change, Skymet Weather

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