by simple requirements and registration. And you could even fix the number of private clubs to make sure that some places would have to stay non-smoking.
As I said, smokers are now a minority and should expect to be treated as such. There are good science studies that show the 2nd hand effect is overstated...but that doesn't change the fact that there are folks like you who cannot be around the stuff and should, by all measure, have establishments to frequent that don't allow smoking.
Imric's point is also valid, it should NOT require a complete ban by legal means. It can and should be accomplished within the framework we have already established. Perhaps a reduction in license fees and taxes for those places that go smoke free and a hike in those same fees for those places that don't. It would create the niche areas for each without such a broad stroke.