Noida (UP), Jan 21 (PTI) The air quality was in the "very poor" category in Ghaziabad and Noida while it was "poor" in Greater Noida, Faridabad and Gurgaon, according to data issued by a government agency on Thursday.

Pollutant PM 2.5 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 Thursday was 326 in Ghaziabad, 306 in Noida, 298 in Greater Noida, 208 in Faridabad and 234 in Gurgaon, according to the CPCB's Sameer app.

The CPCB states that an AQI in the "very poor" category may cause respiratory illness on prolonged exposure, while "poor" causes breathing discomfort to most people on prolonged exposure.

On Wednesday, the AQI was 336 in Ghaziabad, 321 in Greater Noida, 310 in Noida, 201 in Faridabad and 207 in Gurgaon. It was 436 in Ghaziabad, 434 in Greater Noida, 432 in Noida, 416 in Faridabad and 366 in Gurgaon on Tuesday.

On Monday, it was 381 in Ghaziabad, 360 in Greater Noida, 363 in Noida,  332 in Faridabad and 292 in Gurgaon.

The AQI was 368 in Ghaziabad, 384 in Greater Noida, 383 in Noida, 297 in Faridabad and 330 in Gurgaon on Sunday.

The air quality index for each city is based on the average value of all monitoring stations there. Ghaziabad and Gurgaon have three such stations while Noida, Greater Noida and Faridabad have two stations each, according to the app. PTI KIS

(The above story is verified and authored by Press Trust of India (PTI) staff. PTI, India’s premier news agency, employs more than 400 journalists and 500 stringers to cover almost every district and small town in India.. The views appearing in the above post do not reflect the opinions of LatestLY)