High radon exposure in a Brazilian underground coal mine

Abstract

The main source of radiation exposure in most underground mining operations is radonand radon decay products. The situation of radon exposure in underground mining inBrazil is still unknown, since there has been no national regulation regarding this exposure.A preliminary radiological survey in non-uranium mines in Brazil indicated that anunderground coal mine in the south of Brazil had high radon concentration and needed tobe better evaluated. This paper intends to present an assessment of radon andradon decay product exposure in the underground environment of this coal miningindustry and to estimate the annual exposure to the workers. As a product ofthis assessment, it was found that average radon concentrations at all samplingcampaign and excavation sites were above the action level range for workplaces of500–1500 Bq m−3 recommended by the International Commission on Radiological Protection—ICRP 65. Theaverage effective dose estimated for the workers was almost 30 times higher than the worldaverage dose for coal miners.