30 CFR §77.201-2
Verified against eCFR.gov as of June 20, 2026View official text on eCFR.gov ↗
If, at any time, the air in any structure, enclosure or other facility contains 1.0 volume per centum or more of methane changes or adjustments in the ventilation of such installation shall be made at once so that the air shall contain less than 1.0 volume per centum of methane.