Europe does not like smokers anymore; this is fair enough. Europe is prepared to discriminate smokers on the job market. This is the latest frontier of dissuasion and it is a very controversial one.
Is it possible to discriminate on such grounds? It all depends on the reasons one puts forward to keep smokers at bay. Perhaps the World Health Organisation has a high moral ground to do so. It is fighting a global fight against smoke, and it would be slightly inconsistent if those who fight the battle are smokers. They are likely to be half-hearted.
Perhaps a sport club has a reason to insert a clause against smoke in the contracts with its sportsmen as smoke would lower performances.
It is less clear why a smoker would be discriminated against for a post of, say, telephonist in a call centre (the actual case which raised the problem). After all, the working environment is already smoke free. The smoker in question can only harm himself, but does not do anything that can be harmful to others in any possible way. Do we really want to punish him on top of his self-inflicted sanction deriving from the very fact that he is a smoker?