Ghaziabad is the most polluted city in the country followed by Gurugram, Ghaziabad has the worst air quality with an index value of 451 which is followed by Gurugram, Bulandhshahr, Faridabad, Noida, Hapur, Baghpat, Delhi, Greater Noida, Kanpur.
See the following link for more detail -
https://www.indiatoday.in/air-quality/story/11-out-of-14-most-polluted-cities-in-country-are-from-uttar-pradesh-cpcb-data-1379070-2018-10-30
