30 CFR § 75.324
Intentional changes in the ventilation system.
(a) A person designated by the operator shall supervise any intentional
change in ventilation that--
(1) Alters the main air current or any split of the main air current
in a manner that could materially affect the safety or health of persons in
the mine; or
(2) Affects section ventilation by 9,000 cubic feet per minute of air
or more in bituminous or lignite mines, or 5,000 cubic feet per minute of air
or more in anthracite mines.
(b) Intentional changes shall be made only under the following
(1) Electric power shall be removed from areas affected by the
ventilation change and mechanized equipment in those areas shall be shut off
before the ventilation change begins.
(2) Only persons making the change in ventilation shall be in the
(3) Electric power shall not be restored to the areas affected by the
ventilation change and mechanized equipment shall not be restarted until a
certified person has examined these areas for methane accumulation and for
oxygen deficiency and has determined that the areas are safe.