One such supplier, Strata Safety Products, has met the glut of orders head-on but says by the end of this year, it will have completed all manufacturing of its standard emergency refuge chambers initially on order.

The majority of the units will also have been delivered by the end of the year.

Strata said delivery lead times on new orders received were now sitting at about four to six weeks, or in cases where the unit is in inventory, delivery will be immediate.

The US Mine Safety and Health Administration originally proposed the Refuge Alternatives for Underground Coal Mines rule in June this year, outlining an obligation for each of the nation’s 624 underground operations to either build airtight rooms, install rescue chambers or store materials to build a safe refuge in the event of an emergency.

Each shelter would need to provide the MINER Act-required 96 hours of air, water and necessities.

At the time, MSHA anticipated mining operations would have expenses ranging from $US3.1 million to $33.1 million for refuge purchase, installation, moving and repair, pre-shift exams and revisions to plans, maps and programs, and worker training.