The mine has been has been designated as a Category IV "gassy" mine by MSHA. Category IV means that, based on the history of the mine, the ore is noncombustable and that the concentration of methane is neither explosive nor capable of form_ing explosive mixtures with air. Testing for methane is requ1red at least once a shift prior to starting work at each face and upon initial release of gas into the mine atmosphere from boreholes. However, the use of permissible equipment (30CFR, Parr 18) is not required.