One way patients are tested for MCS is done in a glass and metal booth with a separate exhaust and air supply.
"We look at exposure to a chemical -- what we often use is a dryer sheet," Fox said. "The person doesn't know when they're being exposed nor do they smell it. They actually wear a nose plug during the testing. What we monitor is their skin conductance. It reflects the activity in the nervous system.
"What we'll see is that there's a clear change in the person's skin conductance with exposure and no change with the placebo. It's not a way of saying this person is sensitive to this and this, like an allergy test. It says their body is clearly responding when they don't know they're being exposed."