Air pollution in the national capital decreased slightly on Friday, a day after the city's air quality slumped to the "severe" category due to a dust storm in northwest India, the Centre-run weather forecast agency SAFAR said.
The System of Air Quality and Weather Forecasting and Research (SAFAR) recorded the air quality index at 372, which falls in the "very poor" category. However, the Central Pollution Control Board (CPCB) said it remained in the "poor" category, at 279.
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 408 and PM10 at 117, SAFAR said.
PM2.5 can be a matter of more serious health concern than PM10 (particles in the air with a diameter of less than 10 micrometres). Routine exposure to PM2.5 pollutants can lead to diseases like cancer and increases chances of stroke.
PM10 is the prime pollutant in a dust storm.
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SAFAR said high surface winds in northwest India are going to continue on Friday also and the pollution level in the region is likely to decrease slightly on Saturday, with the AQI moving from the "very poor" category to the "poor" category.
However, gusty thunderstorm and occasional episodes of sudden peaking of dust at isolated places in northwest india, including Delhi, will continue for a few days.
On Thursday, the national capital recorded the air quality index at 408, which falls in "severe" category.