Delhi's air quality slightly improved on Sunday after increase in wind speed, the authorities said.
According to the Central Pollution Control Board (CPCB) data, the overall air quality index (AQI) of the city was at 291, which falls in the ''poor'' category.
Delhi's air quality had dipped to ''very poor'' category due to rains, which increased the pollutant holding capacity of air.
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 between 401 and 500 ''severe''.
The CPCB said 16 areas recorded ''very poor'' air quality while 18 areas recorded ''poor'' air quality.
The level of PM2.5 (particles in the air with a diameter of less than 2.5 micrometres) was recorded at 145 and the PM10 level 227, it said.
In the National Capital Region, Ghaziabad and Greater Noida recorded ''very poor'' air quality while Gurgaon and Noida, recorded ''poor'' air quality, the CPCB data showed.
Authorities said the slight improvement in air quality is due to minor improvement in wind speed.
They further added that the air quality would continue to oscillate between ''poor'' and ''very poor'' category for the next three days.
According to the Centre-run System of Air Quality and Weather Forecasting (SAFAR), moderate foggy conditions due to radiation fog and subtle effect of drizzle is still persisting and not allowing air quality to improve.
"However, such conditions cannot get prolonged for long and AQI will start to improve faster after 3 days. there is a partial probability of occurrence of active western disturbance," the SAFAR said.
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