053-3 Wyo. Code R. § 57.22228
(a) Preshift examinations shall be conducted within three hours prior to the start of the shift for which the examination is being made.
(b) Prior to the beginning of a shift following an idle shift, a competent person shall test the mine atmosphere for methane at all work places before persons other than examiners enter the mine.
(c) When one shift immediately follows another, a competent person shall test the mine atmosphere at each active working face for methane before work is started on that shift.
(d) A competent person shall test the mine atmosphere at each face blasted before work is started.
(e) Except in Subcategory I-C or Category III mines, vehicles used for transportation when examining the mine shall be approved by MSHA under the applicable requirements of 30 CFR parts 18 through 36.
053-3 Wyo. Code R. § 57.22228
52 FR, 24941, 7/1/1987, as amended at 53 FR 9615, 3/24/1988