E-Paper
Delhi’s air quality deteriorates, likely to worsen to poor category
An average air quality index (AQI) of 196 (moderate) was recorded in the national capital at 8am compared to 180 (moderate) a day earlier
Delhi’s air quality deteriorated on Wednesday morning and was likely to worsen to the poor category by the end of the day even as a change in wind direction brought the minimum temperature below 20°C (19.4°C) after five days.
An average air quality index (AQI) of 196 (moderate) was recorded at 8am compared to 180 (moderate) a day earlier. The change in the wind direction to northwesterly and a drop in local wind speed was likely to keep the air quality poor for the next two days.
Cold northwesterly winds negatively impact air quality. A dip in temperature slows down the dispersion of pollutants and also brings smoke from the fields of Haryana and Punjab, where farm fires are recorded around this time of the year.
The minimum temperature dipped below the 20°C mark for the first time since Friday when it was 18.6°C. A change in wind direction followed and the minimum temperature rose to 20.9°C on Saturday. On Sunday, it rose to 23.1 and to 24.4°C on Monday. Delhi’s minimum on Tuesday was 22.7°C, two degrees above normal.
“With a change in wind direction, clear skies will return. Northwesterly winds are also cooler, so the minimum is expected to be below 20°C,” said an India Meteorological Department official.
According to an Early Warning System (EWS) forecast, the air quality was likely to be in the lower end of the poor category until Friday. “The outlook for the subsequent six days shows the air quality is likely to hover between poor and moderate.”
EWS is a forecasting system under the Union earth sciences ministry. The Commission for Air Quality Management (CAQM) relies on EWS for pre-emptive action to check pollution.
Delhi recorded its first poor air day this winter season on Friday last when the AQI was recorded at 212. On the same day, CAQM invoked stage-I measures of the Graded Response Action Plan. The measures include shutting down construction and demolition sites over 500 sqm not registered with the government, reduction of road traffic, periodic mechanised sweeping, and water sprinkling on roads, etc.
On Saturday, the AQI deteriorated to 216 (poor) before improving to the moderate range. Delhi’s AQI has been the in moderate category since Sunday.
An AQI between 0-50 is considered 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.
On Monday, CAQM said Delhi recorded 200 good to moderate air days this year, making it only the second time since 2015. The only other time this has happened in the last eight years was in 2020 when the Covid-19 pandemic prompted lockdowns.
