Rather than retype it because I wasn't heard the first time over the din of squabbling, I'll refer Becca back to this post, in which I actually tried to address the problem.

BTW--I have a coworker who is nearly deaf but refuses to get hearing aids and presents a whole set of annoyances in itself. The sniffing is a variant on any number of distractions one can find in a workplace. If your coworker is sniffing and eats with her mouth open, maybe she needs her adenoids or turbinates looked at. Whatever your solution, politeness counts.

SRS