City air worsens due to low wind speed

The city’s air quality entered the ‘very poor’ zone on Monday with the Central Pollution Control Board’s (CPCB) bulletin recording the air quality index (AQI) at 306 — a rise from Sunday’s AQI reading of 288 in the ‘poor’ category

The city’s air quality entered the ‘very poor’ zone on Monday with the Central Pollution Control Board’s (CPCB) bulletin recording the air quality index (AQI) at 306 — a rise from Sunday’s AQI reading of 288 in the ‘poor’ category.

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While the India Meteorological Department’s (IMD) automatic weather station (AWS) for Gurugram did not record the minimum temperature on Monday, the IMD’s AWS at the Palam observatory in Delhi, recorded the day’s minimum temperature at 12.6 degrees Celsius. The city’s maximum temperature stood at 27 degrees Celsius. As per the IMD’s weekly forecast, the maximum and minimum temperatures are expected to hover around 27 and 10 degrees Celsius respectively on Tuesday. The IMD, on Monday, also said that warmer night temperatures are likely to continue over the plains of North India during the next five days.

Experts said that the deterioration of air quality was on the account of low surface winds which were not favourable for effective dispersal of pollutants.

VK Soni, head of IMD’s environment monitoring and research centre, said that the AQI is expected to improve in the next two days due to better ventilation conditions. “While the wind speed is not improving much, the mixing height is increasing day by day due to which we can expect better ventilation and subsequently better air quality in the next two days,” said Soni. The mixing height is the vertical height at which suspended particles mix with the air

The level of ultra-fine particulate matter having a diameter of 2.5 microns or less (PM 2.5), the city’s primary pollutant, was 232.55 micrograms per cubic metre (µg/m³) on Monday, 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 540.25µg/m3 on Monday.

According to the early air quality warning system for Delhi-NCR, the air quality is likely to improve marginally on account of better ventilation but remain in the lower range of ‘very poor’ category until Wednesday. Subsequently, the air quality is likely to remain largely in the lower range of ‘very poor’ category over the next five days. Further improvement in air quality is expected after February 20.