do all truckers have bad breath?

My boyfriend has breath that smells like mothballs ever since we met. Could it be a trucker problem?

I know he doesn't brush every night on the road and I have tried to gently tell him to. Maybe it's a trucker thing brought on by living with the fumes.

Does anyone else have this problem? He seems healthy and of course if he had the time he wouldn't go to a doctor.