To be fair however, if I catch lung cancer the first thing someone asks me is if I smoke or if I know someone who does. If I say yes, smoking gave me lung cancer. I mean, they're a bit quick to drop the axe when it comes to that.

Other studies have suggested that if you are a full-time smoker for many years, you can quit and have lungs that are undiscernable from a non-smoker 3 years later, with similiar drop in likelihood of getting cancer and smoking related illnesses.

That to me, suggests, that casual contact with smoke isn't something that you should freak out about. Your body is capable of removing tar from your lungs, otherwise you'd have black lungs if you were so much as a boy scout leader standing over too many campfires.