Strong winds brings relief from sudden spike in pollution in Delhi

Delhi’s air quality index (AQI) reading on Thursday was 97 — an improvement of 138 points from Wednesday, when the AQI was 235

Strong and consistent easterly winds, combined with scattered rain in parts of the National Capital Region (NCR), led to Delhi recording a sharp improvement in its air quality on Thursday, as the city’s pollution levels dropped to the “satisfactory” category, a day after rising to the “poor” zone.

People enjoy the weather after a brief spell of rain at Yamuna’s Vasudev Ghat on Thursday. (Raj K Raj /HT PHOTO)

According to the daily bulletin released by the Central Pollution Control Board (CPCB) at 4pm, Delhi air quality index (AQI) reading on Thursday was 97 — an improvement of 138 points from Wednesday, when the AQI was 235.

“Easterly winds with an average speed of 10-15 kmph have been prevailing in Delhi since Wednesday night. These wind speeds went as high as 30 kmph and brought moisture, and helped settle pollutants too. We have also seen the impact of isolated rain in neighbouring states like Punjab, Haryana and Uttar Pradesh, which in turn had an impact on Delhi too,” said Mahesh Palawat, vice president at Skymet, a private meteorology service.

CPCB classifies AQI between 0-50 as “good”, between 51 and 100 as “satisfactory”, between 101 and 200 as “moderate”, between 201 and 300 as “poor”, between 301 and 400 as “very poor”, and over 400 as “severe”.

Wednesday’s AQI was Delhi’s highest in nearly three months, since it touched 306 (very poor) on June 19. It was also the first time in nearly six years that Delhi’s AQI crossed 200 in the month of September. The last time this occurred was on September 29, 2018, when the AQI was 219.

Forecasts by the Centre’s Early Warning System (EWS) for Delhi stated that the AQI in the region is likely to be in the “satisfactory” on Friday, before deteriorating to the “moderate” category over the weekend. “The outlook for subsequent six days is that the air quality is likely to be in the moderate to poor category,” it stated.

Meanwhile, parts of the Capital on Thursday witnessed very light rain. However, only one weather station in the city — Palam — logged rain between 8.30 am and 5.30 pm, recording 0.4mm rain during this period. The Safdarjung observatory, representative of Delhi’s weather, has not received any rain since September 19.

To be sure, Delhi has already logged 192.5mm of rainfall so far this September — far in excess of the monthly average of 123.4mm.

India Meteorological Department (IMD) forecasts show that there are chances of isolated rain across the city till Saturday.

Separately, Delhi’s maximum temperature was 35.7°C on Thursday, which is a notch above normal, and around the same as the 37.5°C a day earlier. The minimum, meanwhile, was 25.6°C, which was two notches above normal. It was 26.8°C on Thursday.