It may sound harsh, but I would not hire this babysitter again. Did she agree to not smoking around your child when you asked her about it, and then light up as soon as you had left? Not only is this irresponsible towards the child (not to mention her own health), but it is also a breach of your trust. Who knows what else she might do when you're not looking? Asking her once really should be enough!
if this has been going on 4 a year im sorry but id of got shot of her a long time ago,im a smoker with kids i dont smoke in my house with them i certainly wouldnt tolerate a sitter doin this.find your self some one else who respects your wishes for your child.
I am a nanny and this shouldn't be going on. The childs health is so much more important. I love "my children" that if i smoked i wouldn't at work. Bottom line!I would fire her right away. If she does that against your request what else is she doing?