It's true that the smoke that starts inside stays inside but not all apartments have connected ventilation. And, to be fair, the argument that we get so many carcinogens anyway is a wee bit specious. There's a cumulative effect in these materials and taking one element out of the system must make a difference.
There is surely now no doubt that passive smoking causes actual harm as well as personal distress for individuals. Right now there is a section of the strata Act that says even if you live in a pet-friendly building, if your pet is damaging someone else's health (through allergies etc) it has to go (see below, but bear in mind the the legal term nuisance is a lot more specific than just 'annoying').
So, if you can force someone to give up a pet, why not smoking if, in fact, it does cause a problem for someone else. People have the right to damage their own health (with some drugs but not others) but you don't have the right to damage someone else's, including your own kids.
I can see the day come soon when there will be designated smoking and non-smoking buildings … until someone in a smoke-friendly building gets cancer and sues the OC for encouraging them to smoke.
151 Order relating to animal kept in accordance with by-laws(1)
An Adjudicator may make one of the following orders if the Adjudicator considers that an animal kept on a lot or the common property in accordance with the by-laws causes a nuisance or hazard to the owner or an occupier of another lot or unreasonably interferes with the use and enjoyment of another lot or of the common property:
(a) an order that the person keeping the animal cause the animal to be removed from the parcel within a specified time, and to be kept away from the parcel,