Vaping Problem

I am having an issue with riders vaping in my car and then lying to my face telling me that they are not! I know they are! I can smell it even when they get in the car. I actually watched a girl tell me she wasn't vaping, get out of the car and start vaping again.

What do I do? How should I address this? This is extremely frustrating for me! I care about MY health. I am trying my best to restrain myself.....