As indicated by the record, an AQI somewhere in the range of 0 and 50 is considered 'good', 51 and 100 'agreeable', 101 and 200 'moderate', 201 and 300 'poor', 301 and 400 ' very poor', and 401 and 500 'severe'.
The normal 24-hour AQI at 4 pm on Sunday was 251 in Ghaziabad, 238 in Noida, 224 in Greater Noida, 218 in Faridabad and 209 in Gurugram, as indicated by CPCB's Sameer application. However, on Saturday it was 218 in Ghaziabad, 167 in Noida, 180 in Greater Noida, 198 in Faridabad and 170 in Gurugram.
On Friday it was 91 in Ghaziabad, 114 in Noida, 144 in Greater Noida, 105 in Faridabad and 160 in Gurugram.
The CPCB states that an AQI in the "moderate" may prompt breathing distress to individuals with asthma, lung and heart infections while "poor" may make breathing inconvenience the vast majority on continued exposure.
The AQI for every city depends on the normal estimation of all observing stations there. Ghaziabad, Gurugram and Noida have four such stations while Greater Noida and Faridabad have two stations each, as indicated by the application.