Spraying Perfume in the workplace

A co-worker continues to spray perfume after she goes out to smoke. I have told my employer and they have spoken to her and she of course denies spraying the perfume. It is causing me to have migraines every single day from the smell. They said that they were going to move me and now they tell me they are going to move me from my desk to the desk right next to mine, which faces the opposite direction (which would do absolutely nothing because the perfume she sprays seems to filter out of her office, down the hall and end at my cubicle). How they think moving me to a desk right next to mine would solve the problem, I don't know. Are they required to move me to where I do NOT smell it, because obviously she is going to continue to spray it and nothing will be done by my employer about it.