Abstract: Objective To investigate the level of radioactive occupational hazards in metal mine workplaces in Hunan Province,and provide the latest data for disease prevention and regulation. Methods Five metal mines in Hunan Province were selected,and from 2020 to 2022,the radon activity concentration and γ external exposure level in the workplace were monitored in each mine every year,estimating individual annual radiation dose. Results The range of radon activity concentration in five metal mine workplaces was 11.9-13 497.0 Bq/m³ underground and 23.8-3 056.0 Bq/m³ above ground. The equivalent dose rate of γ external irradiation was 0.09-0.44 μSv/h underground and 0.08-1.53 μSv/h above ground. The average radon activity concentration in A and B mines was over 1 000.0 Bq/m³,and the radon activity concentration in the ground ball mill of B mine was over 1 000.0 Bq/m³. The measured γ external irradiation value in the mineral processing area of B mine was more than twice the natural background value. Conclusion Both A and B mines should take a series of protective measures to ensure that the annual effective dose of underground workers is less than 20 mSv. However,the most important measure at present is to legislate the inclusion of non-uranium mines with radon concentration over 1000 Bq/m³ in radiation protection management,and to incorporate underground non-uranium miners with higher radon-induced annual doses into radiation work management.

Key words: Metal mines, Workplaces, Radon activity concentration, γ external radiation exposure, Annual effective dose