The air quality was recorded in the "very poor" category in Greater Noida while it was "poor" in Noida, Ghaziabad, Gurgaon and Faridabad on Thursday, according to data issued by a government agency.
Levels of PM2.5 and PM10 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 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 was 287 in Ghaziabad, 307 in Greater Noida, 260 in Noida, 277 in Faridabad and 268 in Gurgaon, according to the CPCB's Sameer app.
On Wednesday, it was 221 in Ghaziabad, 239 in Greater Noida, 152 in Noida, 163 in Faridabad and 122 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 each, according to the app.
(This story has not been edited by NDTV staff and is auto-generated from a syndicated feed.)