The air quality remained “severe” in Noida, Greater Noida, Ghaziabad, Faridabad, and Gurgaon in the National Capital Region (NCR) on Sunday, affecting healthy people, according to a government agency.
The 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 at 4 pm on Sunday was 434 in Gurgaon, 456 in Ghaziabad, 440 in Greater Noida, 428 in Noida, and 426 in Faridabad, according to the CPCB's Sameer app.
It was 439 in Gurgaon, 436 in Ghaziabad, 428 in Greater Noida, 426 in Noida, and 414 in Faridabad on Saturday.
PM 2.5 and PM 10 were the prominent pollutants in these satellite cities of Delhi, where the average AQI remained at 416 on Sunday, according to the app.
As per the CPCB, an AQI in the "severe" category affects healthy people and seriously impacts those with existing diseases.
The AQI for each city is based on the average value of all stations there. Noida, Faridabad, Ghaziabad have four stations each, while Gurgaon has three and Greater Noida two, according to the app.