So in other words, a few years ago when I was working on a car, in a closed shop, exhaust hose attached, but unaware of a hole in the exhaust, I should have known sooner I was poisoning myself?? I realized that I was feeling faint and headed out the door. I don't remembering even getting outside, don't remember opening the heavy shop door. All I remember is a buddy that happened to stop by, finding me sitting, passed out in a snow bank along side the shop. If I had not caught myself feeling faint, or the shop door was farther away, I would not be here today. I noticed nothing untill I felt dizzy. Greg