30 C.F.R. § 57.22220 Air passing unsealed areas (I-A, II-A, III, and V-A mines).
Title 30 - Mineral Resources
Air that has passed by or through unsealed abandoned or unsealed inactive areas and contains 0.25 percent or more methane shall— (a) Be coursed directly to a return airway; (b) Be tested daily for methane by a competent person; and (c) Not be used to ventilate work places.
Title 30: Mineral Resources
PART 57—SAFETY AND HEALTH STANDARDS—UNDERGROUND METAL AND NONMETAL MINES
Subpart T—Safety Standards for Methane in Metal and Nonmetal Mines
Ventilation
§ 57.22220 Air passing unsealed areas (I-A, II-A, III, and V-A mines).
