The air quality was recorded in the 'poor' category in Faridabad and Gurgaon, and 'very poor' category across Noida, Greater Noida and Ghaziabad, a government agency said on November 30.
The presence of pollutant PM 2.5 and PM 10 also remained high in the five neighbouring cities 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 Monday was 298 in Faridabad, 291 in Gurgaon, 346 in Noida, 349 in Greater Noida and 377 in Ghaziabad, according to CPCB's Sameer app.
On Sunday, it was 236 in Faridabad, 242 in Gurgaon, 268 in Noida, 273 in Greater Noida and 300 in Ghaziabad. The CPCB states that an AQI in the 'poor' category may cause breathing discomfort to most people on prolonged exposure, while "very poor" may cause respiratory illness on prolonged exposure.
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 has two, according to the app.
For all pollution related news, click here