Ah, I know two dogs that have died of lung cancer because their owners smoked. My aunt and uncles previous JRT, yes the same aunt and uncle who now have the seriously obese Meg who I posted a photo of and and a white GSD who belonged to a work colleague who smokes along with her husband.

The GSD was only 6 and the JRT was 10. They don't live far from each other either. Probably takes about 15 minutes to walk from one house to the other. If two dogs in such a close proximity can die because of their owners habit, how many more do all over the UK and elsewhere.

Sorry to dampen things here but I don't see why, if smoking can be so harmful to humans, that it can't also be harmful to cats and dogs.
I know many pets don't get lung cancer from living in smoking homes same as not all people get smoking related illnesses from either smoking themselves or breathing in somebody elses smoke but the risk is still there.
Many people wouldn't think of having their children breathing in their cig smoke...although some don't care...but they don't bat an eyelid when it comes to their pets.