Noida (UP), Jan 29 (PTI) The air quality plunged to the 'severe' category in Ghaziabad, Noida and Greater Noida while it was 'very poor' in Gurgaon and Faridabad on Friday, according to data issued by a government agency.
Levels of PM2.5 and PM10 also remained high in the air of the five cities neighbouring Delhi, according to the air quality index (AQI) maintained by the Central Pollution Control Board (CPCB).
According to the index, 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 was 423 in Ghaziabad, 415 in Noida, 420 in Greater Noida, 392 in Faridabad and 342 in Gurgaon, according to CPCB's Sameer app.
According to the CPCB, an AQI in the 'poor' category can lead to breathing discomfort for most people on prolonged exposure while a 'very poor' AQI may cause respiratory illness on prolonged exposure.
The AQI for each city is based on the average value of all air quality monitoring stations there. Ghaziabad and Gurgaon have three such stations and Noida, Greater Noida and Faridabad have two each, according to the app. PTI KIS DIV DIV