Of course! I suspect it's a function of how densely populated the area is. I visited Ladakh, and that was obviously much cleaner and nicer. Delhi, Agra and Jaipur were much more polluted, and my experience was limited to that.
I hope one day I can visit again and see more of the country, and not asphyxiate in the process! :)
India is a wonderful country, but the pollution really ruins it.