Noida (UP), Nov 2 (PTI) The air quality in Noida, Greater Noida, Ghaziabad, Gurgaon and Faridabad in the National Capital Region (NCR) recorded marginal improvement on Monday but oscillated between "poor" and "very poor" levels, a government agency said.

Concentration of major air pollutants, 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).

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According to the index, an AQI between 0 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 AQI was 310 in Greater Noida, 356 in Ghaziabad, 304 in Gurgaon, 399 in Noida and 298 in Faridabad, according to the CPCB's Sameer app at 4 pm.

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It was 388 in Greater Noida, 384 in Ghaziabad, 306 in Gurgaon, 384 in Noida and 354 in Faridabad at the same time on Sunday.

PM 2.5 and PM 10 were prominent pollutants in Ghaziabad and Gurgaon, while it was PM 2.5 alone in Noida, Greater Noida and Faridabad, according to the app.

All five satellite cities of Delhi have four air quality monitoring stations except for Greater Noida, which has two. The AQI for each city is based on the average value of all stations there, according to the app.

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

(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)