NOIDA: The air quality was recorded in the "very poor" category in Ghaziabad, Noida and Greater Noida, while it was "poor" in Gurgaon and Faridabad, according to data issued by a government agency on Saturday.
Pollutant PM 2.5 and PM 10 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 Saturday was 338 in Ghaziabad, 302 in Noida, 308 in Greater Noida, 278 in Faridabad and 281 in Gurgaon, according to CPCB's Sameer app.
On Friday, it was 423 in Ghaziabad, 415 in Noida, 420 in Greater Noida, 392 in Faridabad and 342 in Gurgaon.
The CPCB states that an AQI in the 'poor' causes breathing discomfort to most people on prolonged exposure, while 'very poor' may cause respiratory illness on prolonged exposure.
The AQI for each city is based on the average value of all monitoring stations there.
Ghaziabad, Gurgaon and Noida have four such stations while Greater Noida and Faridabad have two stations each, according to the app.