MSHA issued a statement addressing improvements that were made to the safety standards of refuge components addressing breathable air, harmful gas removal and air monitoring.

Back-up regulators have been installed to provide miners with oxygen if one regulator fails. Compressed oxygen systems have also been redesigned to reduce the risk of oxygen fire.

Scrubbing and airlock-purging systems have been subjected to performance testing to ensure miners are not exposed to excess carbon dioxide or carbon monoxide while occupying the refuge alternative.

Air monitoring instruments have been made readily available to measure levels of methane, oxygen and carbon dioxide/monoxide inside the airlock and main chamber.

MSHA also advises changes to safety procedures and training.

It recommends miners keep using self-contained self-rescuers while purging the airlock because levels of carbon monoxide inside may be harmful.

The agency says miners must not remove SCSRs until all miners are inside the main chamber and air monitoring devices indicate it is safe to do so.

Mine operators are being required to train miners on the benefits provided by breathable air, harmful gas removal and air monitoring components.

It is hoped that these changes will ensure the safety of miners in an event when evacuation of the mine is not possible.