The air quality remained "severe" in Ghaziabad, Noida and Greater Noida for the second day, while it stayed in the "very poor" category in Faridabad and Gurgaon, according to a government agency data issued on Saturday. Presence of pollutant PM 2.5 and PM 10 also remained high in the five immediate neighbours of 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 pmon Saturdaywas 434 in Ghaziabad, 414 in Noida, 408 in Greater Noida, 347 in Faridabad and 338 in Gurgaon, according to CPCB's Sameer app.
On Friday it was 440 in Ghaziabad, 414 in Noida, 415 in Greater Noida, 383 in Faridabad and 318 in Gurgaon. The CPCB states that an AQI in the "very poor" category may cause respiratory illness on prolonged exposure, while air quality in the "severe"zone affects even healthy people and seriously impacts those with existing diseases.
The AQI for each city is based on the average value of all stations there. Noida, Faridabad, Ghaziabad have four stations each, while Gurgaon has three and Greater Noida two, according to the app..