To trained immunologists such as Khan, there's another possible explanation for Rea's success: His patients are ill, but from stress and other psychological factors.
"You can have people stressed out and they can break out in a rash or hives or all sorts of things just from the nervous excitement," he said. "These things are real events. But it's not because of the substance they just ingested, it's because of their conditioned response and so when they smell whatever the odor is, they have this conditioned response, they feel ill, their pulse rate may go up, they have a headache, a variety of things."
Getting away from it all was a matter of survival for Nagy. She moved to an island -- Martha's Vineyard -- and created a special pollutant-free home -- Rea style.
"Most of these patients who have these ailments actually have an underlying psychiatric problem, and one of the problems in this country is the under diagnosis and under treatment of psychiatric diseases, and I think we are all guilty of that," Khan said.
Nagy said, "I tried to communicate with the psychiatrists who take care of me, to invite him over to Bill Rea's clinic. To educate him how many of these patients appear to be mentally deranged or have mental issues, but how in fact when you treat their chemical sensitivity, then their mental situation gets much better."
It is a fact that Rea and his methods are controversial, scorned by many mainstream medical researchers and institutions. But all that simply makes no sense to those who say the world made them sick, and Dr. William Rea made them better.
"I don't want to get all choked up," Nagy said, "but he gave me my life."
Click here for more information on Lisa Nagy's Story and environmental medicine. Environmental medicine is not an official branch of the American Medical Association. Click here to find out more information on allergens from the The American Academy of Allergy Astham and Immunology.
ABCNews.com Producer Katie Escherich contributed to this report.