How do you deal with a close talker?

I have a coworker who does not understand that four inches of space between our faces (no joke) is not appropriate. She doesn’t generally have bad breath or anything it’s just very uncomfortable every single time we speak in person. I’ve tried backing up, turning away, and jokingly saying “Whoa, too close!” but…still she’s oblivious. Any ideas? It seems like a silly issue to bring to anyone’s attention besides her, but there is also a language barrier, she’s Thai and frequently misunderstands me.