Air quality dips to very poor, experts cite slow winds

The city’s air quality entered the very poor zone of the Central Pollution Control Board’s air quality index (AQI) bulletin on Tuesday, recording a value of 313, a spike from Monday’s AQI of 298 that was in the poor category

The city’s air quality entered the very poor zone of the Central Pollution Control Board’s air quality index (AQI) bulletin on Tuesday, recording a value of 313, a spike from Monday’s AQI of 298 that was in the poor category. Experts said that the deterioration was due to slower wind speeds during the day and calm wind conditions during the night, which were unfavourable for effective dispersion of pollutants.

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VK Soni, head of India Meteorological Department’s (IMD) environment monitoring and research centre, said that the AQI is expected to remain in the very poor zone for the next few days. “The winds were calm and have further slowed down. There is no immediate expectation of improvement in the air quality, at least for the next three days,” said Soni.

He said that the while winds of up to 10 kmph is expected to prevail during the daytime, winds in the evening and night will be calm.

The level of ultrafine particulate matter having a diameter of 2.5 microns or less (PM 2.5), the city’s primary pollutant, was 210.38 micrograms per cubic metre (µg/m³) on Tuesday, as per the CPCB’s air quality monitor at Vikas Sadan in Sector 11. At the official monitor in Sector 51, the PM 2.5 concentration stood at 388.79 µg/m3 on Tuesday. The PM 2.5 concentration at Gwal Pahari stood at 232.56 µg/m3. In comparison, the safe limit of PM2.5 is 60 µg/m³.

According to the early air quality warning system for Delhi-NCR, the air quality is likely to deteriorate marginally but remain in the very poor category on Wednesday, Thursday and the next five days.

As per the System of Air Quality and Weather Forecasting And Research (Safar) forecast, surface winds are slow, in the south to south-westerly direction, with a further dip expected. It further stated that the AQI is likely to touch the higher end of the very poor zone by Friday.

While the IMD’s automatic weather station (AWS) for Gurugram did not record the minimum temperature on Tuesday, the AWS at the Palam observatory in Delhi recorded the day’s minimum temperature at 10.6 degrees Celsius. The city’s maximum temperature stood at 26.1 degrees Celsius, an increase of three degrees from the 23.5 degrees Celsius recorded the previous day. As per the IMD’s weekly forecast, the maximum and minimum temperatures are expected to hover around 25 and 10 degrees Celsius, respectively, on Wednesday.