The air quality was recorded in the ''very poor'' category in Ghaziabad, Noida, Greater Noida and Faridabad while it was ''poor'' in Gurgaon on Monday, according to data issued by a government agency.
Levels of PM2.5 and PM10 pollutants also remained high in the air of the five cities neighbouring Delhi, according to the air quality index (AQI) maintained by the Central Pollution Control Board (CPCB).
According to the 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 24-hour AQI at 4 pm was 381 in Ghaziabad, 360 in Greater Noida, 363 in Noida, 332 in Faridabad and 292 in Gurgaon, according to the CPCB's Sameer app.
On Sunday, the AQI was 368 in Ghaziabad, 384 in Greater Noida, 383 in Noida, 297 in Faridabad and 330 in Gurgaon.
According to the CPCB, an AQI in the ''poor'' category can lead to breathing discomfort for 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 and Noida, Greater Noida and Faridabad have two stations each, according to the app.
(This story has not been edited by NDTV staff and is auto-generated from a syndicated feed.)