I remember when I was still smoking and trying to figure out a way to quit I went into a shop where they sold herbal cigarettes and asked at the counter if they had any that weren't going to be harmful to my lungs.
The man at the counter didn't quite laugh me out of the store, but it was close. He essentially told me that anything that you draw into your lungs that isn't pure air is going to be harmful in some way.
I found that going cold-turkey was the best way to quit my nicotine addiction anyway. I'm pretty sure if I kept smoking some other kind of cigarettes, they would have just reminded me so intensely of normal smokes that it would have been impossible to stay away from them.