Well, I don't date much at all (for other reasons) and I'm not aerosol reactive but I've handled it two ways so far.
1) if it's a person who's already friends with me and I get an inkling they want more, I start posting things to facebook. People who are interested in you pay attention to the articles you post, and if it's something relevant to their relationship to you, they'll comment on it or bring it up next time you talk to them in person. So, I'll post any stories that come up in the news about kids having reactions from being kissed or at a party and say something like, "relatives, this is why you don't get to kiss me at christmas" or "this is why I had to leave the office party, sorry I had to miss it!". If they don't bring up the allergy next time I see them (and I know they've had the chance to see it on my wall) then they either don't like me enough to care, or it makes them uncomfortable, or whatever. It serves as a red flag.
2) if it's someone new, I'm just upfront. I tell them, I'm allergic to nuts, if there's anyway you might think you want your lips anywhere near me when we go out, you can't have eaten nuts that day. And I make suggestions of places to go. "Sorry, I have an allergy, so I can't do chinese, but we could do W, X, or Y. We could try Z, but there's a chance I might have to leave." Then, once you're in a safe space, and he's seen you manage it a couple times, like when you order or wipe down the movie theater seat, you can talk more about sensitivity levels.
What's really nifty, now that the allergy rates have gone up (when I was growing up it was just me), every once in a while I'll mention it off-hand and the friend will ask, "oh, do you have an epi-pen? My (insert relative/friend) has an allergy!"
The downside is that I have it on my okcupid profile, and stupid okcupid keeps trying to match me with people who've put PB as one of the 6 things they can't live without. Your algorithm is a bit off there, okc.