At the West Coast Haunters Convention we got an interesting tip, and that was to put a sign out as a legal notice to people with health issues. I never considered the legal impact that it could have if my fog set off a breathing attack, or the strobes that i was using set off a siezure? I'm not a lawyer, and i'm not going to guarantee this is going to cover you, but this is close to what they said that you should put out with your display in sign form.
Theatrical fog, and lighting effects are in use on this property, if you have health problems that could be affected by strobe lighting, or artificial fog you should not enter.
Thats kind of the jist of it, like i say, thats not word for word of what they suggested, but it would'nt but a bad idea to put something out. As a side note, the standard fog that you get at the store can cause an asthma attack, where Froggys will not, it's water based, and the ingredients are very high quality. The Rep. is an asthmatic himself, and he works around it all the time.