Environmental protection and public health agencies in the United States and elsewhere label radioactive radon gas a toxic environmental hazard and a major cause of lung cancer. Paradoxically, in Europe and Japan radon gas is also used as an analgesic and anti-inflammatory, as one choice in the spectrum of conventional medical care. Although it is possible to find radon therapy in the United States, it exists only as an unconventional practice in Montana “radon health mines.” In this article, I examine the use of radon therapy by Americans despite intensive public health education media campaigns. Using the notion of explanatory models as an analytical framework, I argue that American health mine clients adjust or replace “toxic models” of radon with new kinds of explanatory models that allow radon to be redefined as a healing substance. The manner of this adjustment varies according to peoples’ individual needs, their own preexisting cultural models and experiences, and their individual personalities; the source of authoritative knowledge accepted by each person is a strong influence. Through these altered explanatory models, mine clients are able to view their use of radon therapy as a rational course of action.