The overall air quality of Delhi remained 'very poor' on Wednesday due to insufficient rainfall and moderate wind speed, authorities said.
According to the Central Pollution Control Board (CPCB) data, the overall air quality index (AQI) of the city was at 349, which falls in the 'very 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 between 401 and 500 'severe'.
The CPCB said 25 areas in the national capital recorded 'very poor' air quality, while three areas had 'poor' quality air.
Two areas -- Shadipur in central Delhi and Wazirpur in northwest Delhi -- recorded 'severe' air quality.
The level of PM2.5 (particles in the air with a diameter of less than 2.5 micrometres) was recorded at 179 and the PM10 level was 293, it said.
In the National Capital Region, Ghaziabad, Greater Noida and Noida recorded 'very poor' air quality, while Gurgaon recorded 'poor' air quality, the CPCB data stated.
Authorities said air quality has not improved significantly as the rainfall was not enough.
"Air quality has not improved significantly as rainfall was not sufficient and the wind speed was also moderate. The AQI is expected to improve slightly but not significantly. It will remain oscillating between 'poor' and 'very poor' for next the three days," the Centre-run System of Air Quality and Weather Forecasting (SAFAR), said.
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