The AQI for each city is based on the average value of all stations there. (File)
The average air quality plunged to "very poor" levels in Ghaziabad and Greater Noida, "poor" in Noida and Faridabad while stayed "moderate" in Gurgaon, according to a 24-hour data issued by a government agency on Thursday.
Pollutants PM 2.5 and PM 10 although 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).
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 on Friday was 304 in Ghaziabad, 312 in Greater Noida, 261 in Noida, 256 in Faridabad and 163 in Gurgaon, according to CPCB''s Sameer app.
On Thursday it was 294 in Ghaziabad, 288 in Greater Noida, 236 in Noida, 240 in Faridabad and 204 in Gurgaon. On Wednesday it was 234 in Ghaziabad, 239 in Greater Noida, 200 in Noida, 203 in Faridabad and 175 in Gurgaon.
On Tuesday it was 148 in Ghaziabad, 120 in Greater Noida, 149 in Noida, 138 in Faridabad and 83 in Gurgaon. On Monday it was 168 in Ghaziabad, 134 in Greater Noida, 152 in Noida, 179 in Faridabad and 65 in Gurgaon.
The CPCB states that an AQI in the "very poor" category may cause respiratory illness on prolonged exposure, "poor" may cause breathing discomfort to most people on prolonged exposure, while "moderate" leads to breathing discomfort to the people with lungs, asthma and heart diseases.
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.