(Wired) – Millions of people suffer debilitating reactions in the presence of certain scents and chemicals. One scientist has been struggling for decades to understand why—as she battles the condition herself.

In 1997, Miller proposed a career-defining theory of how people succumb to this condition. It came with a technical-sounding name, toxicant-induced loss of tolerance, and a convenient acronym, TILT. You can lose tolerance after one severe exposure, Miller says, or after a series of smaller exposures over time. In either case, a switch is flipped: Suddenly, people are triggered by even tiny amounts of everyday substances—cigarette smoke, antibiotics, gas from their stoves—that never bothered them before. These people become, in a word, TILT-ed. It’s not unlike developing an allergy, when the body labels a substance as dangerous and then reacts accordingly. (Read More)