Can Chick-fil-a fire you for being a smoker?

I am a new hire and I asked my trainer what the policy was for smoking cigarettes on break (like where to go). She looked at me coldly and said "dont, just dont...unless you want to get sent home." Just wondering if that's grounds for termination. Hard for me to imagine that every person who works at Chick-fil-a is a non smoker.