A research plan was prepared to measure the effect of moisture on the 222rn emanation coefficient in small uranium ore samples. One version of the plan called for the sealed can to be counted after a long storage and then opened to let the free radon escape. However, a question arose about the information on many emanation coefficient measurements ( for example, ha36, ki32, sh70, st57, and wa51). Reported values for 219rn, 220rn, and 222rn generally differ by less than a factor of 10, which is considerably less than expected from linear diffusion theory (1, 3.7, 290, for 219rn, 220rn, and 222rn, respectively) (ta78). This small difference suggests that radon escape is very rapid, and hence the steady-state flux might be reached within tens of seconds. None of the papers, however, specifically address the question; therefore, the Bureau of Mines performed the analytical study reported in this note.