October 18, 2021 1:42:14 am
Parts of Delhi witnessed rainfall and thundershowers on Sunday, with light rainfall on the forecast for Monday as well. A western disturbance over southern Afghanistan and easterly winds over northwest India have contributed to the prevailing weather conditions over the capital, according to the IMD.
Between 11.30 am and 2.30 pm on Sunday, the IMD’s Safdarjung observatory recorded 15.4 mm of rainfall, while the observatory at the Ridge recorded the highest amount of 19.4 mm within the same time frame. The maximum temperature dipped to 30.4 degrees, 4 notches below normal, while the minimum temperature 23.5 degrees Celsius, 4 notches above normal.
Despite the rain, the city’s air quality index (AQI) remained in the ‘poor’ category for the second consecutive day on Sunday. The Central Pollution Control Board (CPCB) bulletin released at 4 pm said Delhi’s AQI, as a 24-hour average, was 298 — higher than Saturday’s 284. The main pollutant contributing to the air quality on Sunday was PM 2.5. The CPCB categorises AQI between 200 and 300 as ‘poor’.
Pollution levels dipped by Sunday evening, however, falling to figures well within the prescribed standards at most stations, real time air quality data shows. At 7 pm at the Anand Vihar monitoring station for instance, PM 10 levels dropped to 48 µg/m3 down from a high of 346 µg/m3 at 4 am. At Mandir Marg, PM 10 levels fell to 23 µg/m3 at 7 pm from 472 µg/m3 at 4 am. PM2.5 levels at Mandir Marg were nearly zero at 7 pm, as opposed to a figure of 349 µg/m3 at 4 am.
At Anand Vihar, the wind speed also began to pick up after 2 pm, which could have dispersed pollutants. At the Wazirpur station as well, the wind speed peaked at around 2 pm, while PM 2.5 levels simultaneously fell from 90 µg/m3 at noon to 16 µg/m3 at 3 pm.
A forecast on Sunday from the System of Air Quality and Weather Forecasting and Research (SAFAR) said the AQI is likely to “improve significantly and touch the moderate category” on Monday, mostly due to wind direction being from the eastern side and moderate rainfall. Thereafter, the AQI is likely to degrade to the
‘poor’ category for the following two days, according to the update. Low wind speed has been inhibiting dispersion of pollutants.
Owing to rainfall and change in wind direction, the contribution of stubble burning to Delhi’s air quality was only 2% on Sunday, compared to 14% on Saturday, the SAFAR forecast said. The ‘effective’ fire count was 815 on Sunday, down from 1,572 active fire counts mentioned in Saturday’s update.
“For the past one month, I have been tweeting data of air quality in Delhi. Pollution has increased in the last 3-4 days, and it is due to stubble burning in neighbouring states. Farmers in neighbouring states are compelled to burn stubble as their governments are doing nothing for them (towards stopping stubble burning),” Kejriwal said in an event organised to lay the foundation stone of a new government hospital in Shalimar Bagh.
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