Noida (UP), Mar 16 (PTI) The air quality plunged to 'very poor' category in Greater Noida, while it was recorded 'poor' in Noida, Ghaziabad, Gurgaon and Faridabad, according to data issued by a government agency on Tuesday.
Pollutants PM2.5 and PM10 also remained high in the air of 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 291 in Ghaziabad, 313 in Greater Noida, 259 in Noida, 246 in Faridabad and 231 in Gurgaon, according to CPCB's Sameer app.
On Monday it was 224 in Ghaziabad, 208 in Greater Noida, 182 in Noida, 173 in Faridabad and 187 in Gurgaon.
The CPCB states that an AQI in the 'poor' category may cause breathing discomfort to most people on prolonged exposure, while that in the 'very poor' zone may lead to respiratory illness on prolonged exposure.
The AQI for each city is based on the average value of all monitoring stations there. Ghaziabad, Gurgaon and Noida have four such stations while Greater Noida and Faridabad have two stations each, according to the app. PTI KIS CK CK