A steadily mounting rate of uranium production has focused increasing attention on the health hazards associated with the mining of this strategic metal. Predominant among these hazards is exposure to radon, a dense gas emanating from the ore, together with the products which result from the radioactive decay of radon. To date, neither records of human exposure to radon daughter products nor data from animal experimentation have been available in sufficient quantity to permit a determination of a maximum permissible concentration for these elements. It has therefore been necessary to establish a working level which appears to be safe, yet not unnecessarily restrictive to industrial operations. Such a level, it is believed, has been established and recommended in the report. (Author Modified Abstract)