The average air quality was recorded in the "very poor" category in Ghaziabad, Noida, Greater Noida and Faridabad and in the "poor" category in Gurgaon, according to data issued by a government agency on Wednesday.
PM2.5 and PM10 levels remained significantly high in the five cities surrounding Delhi, according to the air quality index (AQI) maintained by the Central Pollution Control Board (CPCB).
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 AQI at 4 pm was 388 in Ghaziabad, 398 in Greater Noida, 348 in Noida, 367 in Faridabad and 276 in Gurgaon, according to CPCB's Sameer app.
On Tuesday, it was 324 in Ghaziabad, 312 in Greater Noida, 278 in Noida, 260 in Faridabad and 213 in Gurgaon.
According to the CPCB, an AQI in the "poor" category causes breathing discomfort to 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 while Noida, Greater Noida and Faridabad have two stations each, according to the app.
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