Yes it's been proven. After a study was carried out a few years back, during or after the Roy Castle case I think, they found that non-smokers sitting in smokey clubs and pubs showed well over their normal limit of carbon monoxide, and that was only after a few hours. So to say it doesn't effect but only irritates others, is not quite true.
The new campaign on tele' which shows the kids breathing out smoke is really hard hitting, and that's why I've always stayed to just one room in the house that the kids are not allowed to come into. And I always sit here with the window open a touch.