It's a sin??

So, Darin was reading over my last post, and we got into a little "discussion" about smoking. The first time Darin read the post I had written that smoking was wrong. I later changed it to smoking is harmful and yucky. Why? Well, to me saying smoking is wrong is pretty close to saying it is sinful and I don't feel comfortable saying that because it's one of those things I don't have an answer to (among many other things).

So back to our discussion. Darin noticed the change in words and I told him why I made the change and he pulled out the whole "our body is God's temple" argument. So then I said if he is going to say that smokers are sinning for causing harm to their bodies, he should also be pointing the finger at people who choose to be in situations (like casinos and sports bars) where they are exposed to second hand smoke, which also has many negative effects. Darin thought my argument was weak because the person ingesting the second hand smoke wasn't actually doing the "wrong" thing.

So, what do you think? I am not so much looking for an opinion on whether or not smoking is a sin, but if we say it IS a sin, then is putting yourself in a situation (that is more for recreation/entertainment than something you really need to do) where you are exposed to second hand smoke also a sin?