If you are inhaling it everyday but only for a short amount of time e.g. 30 mins then you will be fine but if you are sat by traffic all day just sniffing it then chances are you'll probaly get Lung Cancer.
What Could Happen If You Inhale Exhaust Fumes?
You could die!
You could die.
I'm guessing to could die from what I've read. My van doesn't have a exhaust pipe so the gases are in the van therefore I inhale it everyday and haven't died yet. But breathing it in on purpose will probably kill you.