Virginia Code Title 45.2. Mines, Minerals, and Energy § 45.2-937. Penetration of underground mines; testing

A. A qualified person shall test for the presence of methane and for a deficiency of oxygen, using an approved device, at the entrance to an auger hole or at a highwall miner entry when either such entry point penetrates a worked-out area of an underground mine.

B. If one percent or more of methane is detected or 19.5 percent or less of oxygen is found to exist, no further work shall be performed until the atmosphere has been made safe.