The problem? As in, the only one? A matter of opinion. As I see it the several carcinogenic components of ICE exhausts are problems. Dying of cancer may be a s

The problem? As in, the only one? A matter of opinion. As I see it the several carcinogenic components of ICE exhausts are problems. Dying of cancer may be a small problem compared to an uninhabitable planet and I can see how one might consider it insignificant in comparison, but in my opinion, cancer is a real problem, including cancer caused by smog.