After a week of ‘severe’ level of pollution, the air quality index (AQI) in Delhi was down to ‘very poor’ on Tuesday due to changing weather conditions, data from the Central Pollution Control Board (CPCB) showed.
Western disturbances
Sathi Devi, head of the National Weather Forecasting Centre, said that due to strong western disturbances, parts of Rajasthan, Punjab and Haryana received rainfall that had a positive impact on the air quality of the Capital.
She said that although Delhi may not receive heavy rainfall, strong winds would blow towards the city from the north-west by Friday, helping to further improve the air quality.
Beginning November 7, the National Capital Region (NCR) saw a spell of heavy smog after still conditions on the ground and winds laden with smoke — from stubble burning, had swept into the Capital from neighbouring States.
The AQI shot up to ‘severe’ for several days, further increasing to the top category of ‘severe+ or emergency’ recently, before finally reducing to ‘very poor’ on Tuesday. Using data from 13 stations, Delhi’s AQI was 308 at 4 p.m.
The ‘very poor’ AQI comes with a health warning that prolonged exposure causes respiratory illness.
The average levels of different pollutants were also down on Tuesday.
The SAFAR index of the Union Earth Sciences Ministry showed that the average concentration of PM2.5, fine particles of 2.5 microns or less in diameter, was 236 micrograms per cubic metre (ug/m3), putting it in the ‘very poor’ category for the first time in a week.
Further dip forecast
The concentration of PM10, comparatively coarser particles of up to 10 microns in diameter, was also in the ‘very poor’ category at 375 ug/m3. Both PM2.5 and PM10 levels were well over three times their standards of 60 and 100 ug/m3, respectively.
In its bulletin, SAFAR forecast further reduction in PM levels on Wednesday.
