Mine atmospheres shall be sampled to determine if hazardous concentrations of radon gas are present. Where potentially hazardous concentrations are found, or known sources of radon exist, each active area shall be sampled as often as necessary by a competent person.
4 Va. Admin. Code § 25-40-3290
Statutory Authority
§§ 45.1-161.3, 45.1-161.294 and 45.1-161.305 of the Code of Virginia.