Fig. 1 Localization of the Brazilian coal mine in this studywhich presented with high levels of radon concentration.High values of 210Po in urine samples of some workers fromthismineindicatedthe inhalationof radonprog-eny as a relevant source of occupational exposure [24].The Figueira
mine geological
characteristics
havebeendescribedelsewhere[25].Inshort,thecoalbasin region is situated near a uranium deposit, wherein ura- nium
mineralizationislocatedinthesedimentaryse- quence
between
the coal seam
and the calcareoushorizon comprising siltite and limestone. Coal is usually found associated with sandstones, carbonaceous siltites andcoalseams.Insandstones,theuraniumminerali-zation is observed as uraninite, and around 70% of the uraninitecanbefoundinthesandstone,and30%incarbonaceous siltites and coal.
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