The air quality largely remained "very poor" in Noida, Greater Noida, Ghaziabad, Gurugram and Faridabad in the National Capital Region, according to a government agency.
Concentration of major air pollutants 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 was 394 in Greater Noida, 382 in Ghaziabad, 379 in Noida, 367 in Gurgaon, 337 in Faridabad, according to the CPCB''s Sameer app at 4 pm on Friday.
Prominent pollutants in Noida, Greater Noida and Faridabad were PM 2.5 and PM 10, it stated. Prominent pollutant in Ghaziabad and Gurgaon was PM 2.5, it added.
All five satellite cities of Delhi have four air quality monitoring stations except for Greater Noida, which has two. The AQI for each city is based on the average value of all stations there, according to the app.
The CPCB states that an AQI in the "very poor" category can lead to respiratory illness on prolonged exposure.
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