Noida: The air quality at some places in Faridabad remained very poor on Monday while it was poor in parts of Gautam Buddh Nagar, Ghaziabad and Gurgaon in the National Capital Region, according to a government agency. Also Read - Delhi's Air Quality 'Poor' as Neighbouring States Report Season's Highest Stubble Burning Count in a Day

There was heavy concentration of PM 2.5 and PM 10 pollutants in the air of the four immediate neighbouring districts of Delhi, according to the air quality index (AQI) maintained by the Central Pollution Control Board (CPCB). Also Read - Delhi Pollution: Air Quality Improves Marginally But Remains in Poor Category

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’. Also Read - Pollution Alert: Delhi Air Quality Drops to 'Poor' Category, First Time Since June 29

The AQI was recorded very poor at some places in Faridabad but largely remained poor , according to the CPCB data at 9 pm.

It was recorded at 300 at the station in Sector 11 followed by 266 at New Industrial Town, 251 at Sector 30 and 230 at Sector 16A, the data showed.

In Gurgaon, an AQI of 294 was recorded by the station in Sector 151 followed by 254 at the Teri Gram, 248 at Vikas Sadan and 171 at NISE Gwal Pahari, it showed.

In Gautam Buddh Nagar’s Noida, the AQI was measured at 264 by the station at Sector 62 and 212 at Sector 116, while the stations at sectors 1 and 125 showed insufficient data for the last 24 hours.

In Greater Noida, an AQI of 264 was recorded in Knowledge Park V while it was 217 in Knowledge Park III, according to the CPCB figures.

Adjoining district Ghaziabad’s Loni had an AQI of 278 at 9 pm followed by 238 both at Sanjay Nagar and at Indirapuram while no official data was available for Vasundhara.

The worsening of the air quality comes even as the Graded Response Action Plan (GRAP) has been implemented in the Delhi-National Capital Region (NCR) from October 15 to check air pollution, which spikes around this time of the year.