NOIDA: The average air quality was recorded "very poor" across Ghaziabad, Noida, Greater Noida, Gurgaon and Faridabad, according to data issued by a government agency on Wednesday.
Pollutants PM 2.5 and PM 10 also remained high 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 Wednesday was 364 in Ghaziabad, 369 in Greater Noida, 328 in Noida, 314 in Faridabad and 309 in Gurgaon, according to CPCB's Sameer app.
On Tuesday, it was 291 in Ghaziabad, 313 in Greater Noida, 259 in Noida, 246 in Faridabad and 231 in Gurgaon.
The CPCB states that an AQI in the "very poor" category may lead to 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.