It seems that for a long time, people possessed an intuitive notion that smoking was bad (it makes you cough, gives you shortness of breath, etc.) but mostly ignored that intuition.
The one thing that bugs me about this was, as a kid in a health class, I was shown a video of a little girl and her grandma. The girl asked the grandma "Why do you smoke grandma?" The old lady responded "Because when I was your age, nobody knew that smoking was bad for you."
The bullcrap we were fed as kids is incredible.
A custome lothsome to the eye, hatefull to the Nose, harmefull to the braine, dangerous to the Lungs, and in the blacke stinking fume thereof, neerest resembling the horrible Stigian smoke of the pit that is bottomlesse.
Just for historical curiousity. I do not want to start a debate about the Nazis.
http://briarfiles.blogspot.com/2008/06/featured-pipe-smoker-...
There should be no difference between 'he knows' & ' he's had it pounded into his head daily.' But there is.