I don't think you walk out quite as healthy from a room full of smoke as you walk in, in fact we probably don't walk out of any room as healthy as when we walked in since we're a little bit older when we leave and we might have killed a few brain million brain cells with a few beers or other drinks, but we're still walking.

The fact that what our vehicles pump into the air a lot more than a smoker is that toxic suggests human beings do indeed have an impact on our environment and that is just one of many ways and when was the last time there were 6.5 billion human beings on earth at one time?