Oh geez snork, what are you trying to do?
Here are some possible answers, so just pick your favorite...
1) Complain to "management" and eventually they will not let people bring them into the airport
2) Give you dirty looks and start to hate all vapers under my breath
3) Not care and move on with my life
4) Appreciate that you are "normalizing" vaping and give you a high five
5) Break out a cigarette because smoking is obviously okay in this establishment
6) Pull you over and let you know that you are giving all vapers a bad name
7) Fake cough and move my child away from you as fast as possible
8) Walk through any cloud you may produce so that it can kill the germs that surround me
9) Insert WHATEVER else here