[Code of Federal Regulations] [Title 30, Volume 1] [Revised as of July 1, 2006] From the U.S. Government Printing Office via GPO Access [CITE: 30CFR57.22220] [Page 411] TITLE 30--MINERAL RESOURCES CHAPTER I--MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR PART 57_SAFETY AND HEALTH STANDARDS_UNDERGROUND METAL AND NONMETAL MINES --Table of Contents Subpart T_Safety Standards for Methane in Metal and Nonmetal Mines Sec. 57.22220 Air passing unsealed areas (I-A, II-A, III, and V-A mines). 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.