Noida (UP), Jan 17 (PTI) The average air quality in Ghaziabad, Noida, Greater Noida and Gurgaon was in the 'very poor' level on Sunday, a day after recording it in the 'severe' category, according to data issued by a government agency.

Faridabad recorded its air quality in the 'poor' category.

Pollutants PM 2.5 and PM 10, however, remained prominent in the air of the five immediate neighbours of Delhi, according to the air quality index (AQI) maintained by the Central Pollution Control Board (CPCB).

An AQI between zero 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 average 24-hour AQI at 4 pm on Sunday was 368 in Ghaziabad, 384 in Greater Noida, 383 in Noida, 297 in Faridabad and 330 in Gurgaon, according to CPCB's Sameer app.

On Saturday, it was 423 in Ghaziabad, 438 in Greater Noida, 434 in Noida, 416 in Faridabad and 316 in Gurgaon.

According to the CPCB, 'poor' air quality causes breathing discomfort to most people on prolonged exposure while 'very poor' air may cause respiratory illness on prolonged exposure.

The AQI for each city is based on the average value of all stations there. Ghaziabad and Gurgaon have three such stations while Noida, Greater Noida and Faridabad have two stations each, according to the app.

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