Dusty winds blowing from as far as Afghanistan and neighbouring Rajasthan have increased the pollution levels in the national capital with the air quality plummeting to the 'poor' category on Friday, authorities said.
Central Pollution Control Board (CPCB) officials said the rise in pollution might be due to dusty winds flowing from the western side, including Rajasthan and Afghanistan.
According to CPCB data, the overall air quality index (AQI) of the city was at 232, which falls under the 'poor' category.
An AQI between 0 and 50 is considered 'good', 51 and 100 'satisfactory', 101 and 200 'moderate', 201 and 300 'poor', 301 and 400 'very poor', and 401 and 500 'severe'.
The level of PM2.5 (particles in the air with a diameter of less than 2.5 micrometres) was recorded at 103 and the PM10 (particles in the air with a diameter of less than 10 micrometres) level was recorded at 226, it said.
The Centre-run System of Air Quality and Weather Forecasting (SAFAR) said the overall air quality over Delhi is in "poor" category.
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On Thursday, the pollution was recorded in the "moderate" category.
"As predicted by SAFAR-model, this deterioration is attributed to medium to long range transport of dust from western side of Delhi (including Rajasthan and Afghanistan) due to favourable upper wind conditions," the SAFAR said.
It said the impact is likely to last until tomorrow.
"The air quality will continue to be in poor category for tomorrow as well. Air quality is predicted to improve to moderate category by March 31," it added.
Last year in June, long range dusty winds had increased the pollution level of the national capital by several folds which had slipped to severe category.