The average air quality plunged to "severe" level in Ghaziabad, Noida, Greater Noida and Faridabad, while it was "very poor" in Gurgaon, according to a 24-hour data issued by a government agency on Tuesday.
Presence of pollutant 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 Tuesday was 458 in Ghaziabad, 450 in Greater Noida, 437 in Noida, 407 in Faridabad and 377 in Gurgaon, according to CPCB's Sameer app.
The CPCB states that an AQI in the "very poor" category may cause respiratory illness on prolonged exposure while "severe" affects even healthy people and seriously impacts those with existing diseases.
The average AQI on Monday was 391 in Ghaziabad, 366 in Greater Noida, 363 in Noida, 289 in Faridabad and 271 in Gurgaon, while on Sunday it was 346 in both Ghaziabad and Greater Noida, 333 in Noida, 294 in Faridabad and 262 in Gurgaon.
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.
(Except for the headline, this story has not been edited by NDTV staff and is published from a syndicated feed.)
Delhi's Air Quality 'Satisfactory' For Second Consecutive Day Due To Rain Delhi Records Maximum Number Of 'Good To Moderate' Air Quality Days In April Delhi Records Maximum Temperature Of 18.6 Degrees Celsius On Sunday 9 Dead, 2,800 Hurt As Pagers Explode Across Lebanon, Hezbollah Blames Israel IndiGo Flight Tailstrike Leaves Huge Dent During Take-Off From Delhi Airport Highlights: Arvind Kejriwal Resigns, Atishi To Be Delhi Chief Minister Kamala Harris Dials Trump After Apparent Assassination Attempt Ghislaine Maxwell's Sex-Trafficking Conviction Upheld, Appeal Planned Stage Set For Phase 1 Of J&K Elections Today, 24 Seats Up For Contest Track Latest News Live on NDTV.com and get news updates from India and around the world.