Authorized limits of radon daughter products in Polish underground metal-ore mines in the light of experience.

The paper presents the results of measurements of individual exposures of miners to radioactive radon daughter products, naturally existing in air of metal-ore mines. Results concern the three year period between 1985 and 1987, during which the observed annual average concentrations were stable and have been recognised as values corresponding to the steady state. They are presented and analysed assuming several possible values of the Authorized Limit of the exposure of miners to radon daughter products. The values: 1 WLM, 2.5 WLM, 3.5 WLM (Working Level Month) were considered and compared with the value of 5 WLM, which is currently the basic limit recommended by the International Commission on Radiological Protection (ICRP), and approved by the WHO, ILO and IAEA. Though the value of 3.5 WLM is presently adopted and officially authorized in Poland as the Authorized Limit of annual individual miners' exposure, the results presented in this paper lead to the conclusion that the value of 2.5 WML could be adopted instead of the current one. This means that the present limit could be decreased by about 30% and without causing any social, technological and economic problems in Polish metal-ore mines.