I'm going to ask her not to smoke
Does smoking bother you?
I hate the smell of cigarette smoke.
Telling other people what to do can really be difficult if your tone is wrong. Try to be as considerate as you can when asking. It is fine if it is your own property or you want to keep the smoke from kids, but if they are doing it where it is allowed then they may take it the wrong way.
I discovered that the smell from cigarette smoke can make me feel really sick
I understand smoking can be harmful to your health, but it's her life and it's best to not tell her what to do with her addictions. It can be really hard to break. How about telling her how it makes you feel, so she knows when and where to smoke?