The rule as implemented goes way beyond that and at the time of introduction suggestions such as separate smoking rooms or increased ventilation were categorically ruled out.
As Christopher Hitchens wrote in the Guardian of the UK smoking ban:
Workers may be forced through economic necessity to tolerate the risk, or may be ignorant of the risk. It is reasonable for the state to require employers to provide safe & healthy working conditions - this includes not being exposed to cigarette smoke.
Surely this is an issue of workers' rights? But that is true only if you assume that a person seeking a job as a waitress or barman, and allergic to smoke, can only find a job in a smoker's paradise. How likely, really, is that? If places of hospitality were plainly demarcated as "smokers welcome" or "no smoking", it is hard to imagine that all involved would not be able to find their way, unaided by the government, to the place that suited them best.
The rule as implemented goes way beyond that and at the time of introduction suggestions such as separate smoking rooms or increased ventilation were categorically ruled out.
There are some occupations which are by nature dangerous, say fishing, diving or lumberjacking. Passive smoke in the workplace is, on the other hand, an entirely avoidable risk. As a smoker myself, I think the workplace ban on smoking - including bars and restaurants - is reasonable.