Allergies are caused by proteins. All allergies.
There are no proteins in tobacco smoke. No one can be "allergic" to tobacco smoke.
Proteins can be very delicate molecules. And proteins in tobacco sure can't survive smoking (that is, the burning of tobacco). Temperatures are to high for proteins and they break apart as tobacco burns.
Now, a person can be allergic to the tobacco plant. It's rare, but it can happen. But no person can be allergic to tobacco smoke. That is a fact. A short fact.
Allergy to Smoke: Myth or Reality:
http://www.beyondallergy.com/indoor-allergies/allergy-to-smoke-myth-or-reality.phpProteins, Immune Activity , Allergy:
http://www.nutramed.com/nutrients/food_proteins_allergy.htm 