Your husband does not have an allergy to cigarettes, it is biologically impossible. A large number of non-protein substances like Kleenex, paper dust, paint fumes, perfume, newsprint and cigarette smoke are erroneously called allergens, but they’re not. They do produce symptoms in many people, but it’s because they’re irritating, not allergic.
Which means he is "allergic" to anything burning. Tobacco allergy does exist but only affects those who handle the raw leaves.