How do they film minors smoking?

Question

Many movies depict children and minors (and non smoking actors) actively smoking a cigarette and blowing actual smoke. How is that done?

Answer 1

Rarely does that happen. Most of the actors that you see in films are 18 or 21 playing 15 and 16.

Can you name a film where a minor is actually smoking? In Leon, Natalie Portman doesn't actually smoke....she holds a cigarette and mimes the actions. I can't think of another film where a real minor is smoking but please let me know what you're refering to.