The new regulations, published in the Federal Register to implement one section of the MINER Act of 2006, were based on data and experiences collected by the agency as well as National Institute for Occupational Safety and Health report recommendations, available research on current and developing technology, public input and existing state regulations.

The two types of refuge alternatives now permitted are pre-fabricated self-contained units and units with 15psi stoppings that are erected “prior to an event in a secure space with an isolated atmosphere”, MSHA said. Those existing shelters approved under mines’ emergency response plans (ERPs) will be gradually phased out.

As part of the final regulations, all underground operations must outline the location, capability and capacity of planned refuge alternatives as part of their ERP and must also address plans to train staff on the units’ location, transport, deployment, maintenance and use.

Pre-shift examinations must also be performed on all refuge alternatives and components, and all crews must be able to locate the shelters on the mine map.

“This final rule will help reassure coal miners that, should a mine emergency occur that prevents them from escaping, they will have a protected, secure area to sustain them while they await rescue," said agency head Richard Stickler.

All approved alternatives have a series of requirements, including 15 square feet or more of floor space per person as well as a volume per person of 30 to 60 cubic feet dependent on mining height.

“The airlock can be included as usable space,” officials noted, adding that when locations are near a working section the capacity of the unit should be the maximum number of miners on or near the section at any given time.

“In an outby area, the capacity is the maximum number of persons reasonably expected to use the refuge alternative,” officials said.

The alternative units must also be located within 1000ft of the closest working face and where mining equipment is being put in or taken out. Shelters are required to be one hour or less in travel time when in outby areas unless a mine requests and the agency approves a different plan.

A 96-hour life span for all refuge alternatives and components is now federal law, but MSHA said that time can be 48 hours if the operation makes advance arrangements for additional surface supplies. Life sustenance items including food, water, light, first aid and sanitation must be included in every unit.

A redundant communication plan must also be in place for the alternatives to be compliant, the agency noted.

“A two-way communication system that is part of the mine communication system – which can be used from inside the refuge alternative – and an additional communication system and other specifications set forth in the operator's approved emergency response plan are required,” MSHA said.