Uranium mines in Colorado and New Mexico were surveyed for airborne concentrations of radon (10043922) and radon daughters. A procedure for measuring individual daughters and the fraction of each existing as free atoms was developed and used for field monitoring. Samples were taken in working areas and particle counts were made. The data was analyzed to determine the ratio of radon to radon daughters as well as the ratios among the radon daughters. The ratios and the fractions of free atoms varied widely. The values of the fractions of free atoms were dependent on concentrations of daughter atoms and particles, residence time of the air, and charge on the atom. In general, the fractions of free radon daughter-A atoms varied inversely with the particle count. Significant fractions of the B- daughter and C-daughter were present in the free state. The author concludes that since the radon to working level ratios have not changed much in 20 years, using the ratio as the basis for estimating relative biological hazards is just as uncertain now as then. The large number of daughters present as free atoms indicate that the lung radiation doses calculated using any of the lung models need reexamination.