Mine rescue chamber

A mine rescue chamber is an emergency shelter installed in hazardous environments, typically underground. Also known as refuge chamber, refuge bay, or refuge alternative. Refuge chambers come in all types and models; suitable for a range of different industries including metalliferous mining, coal, tunnelling and petrochemical facilities. 
In emergencies, when evacuation is no-longer safe or practical, the rescue chamber is designed to provide a safe and secure ‘go-to’ area for personnel to gather and await extraction.
Essentially, rescue chambers are sealed environments built to sustain life in an emergency or hazardous event such as a truck fire or toxic gas release. They provide a secure area with shelter, water, and breathable air, for people to remain until they are rescued or the hazard subsides.
Refuge chambers need to be sealed to prevent the ingress of toxins such as smoke contaminating the breathable air within the chamber. The sealed area has a closed circuit breathing apparatus; where carbon dioxide and other toxins are removed, oxygen is added, and temperature and humidity are maintained, all while protecting occupants from the external threat.
The capacity and duration can vary depending on the chamber build. Communication equipment is also available. The chambers are required to be located in close proximity to worker areas.
Hard Rock Mine Refuge Chamber.
Guidelines and Legislation for Rescue Chambers in Hard Rock Mines
Some examples of refuge chamber legislation can be view below:
Coal Mine Refuge Chamber.
The rescue chambers in a typical coal mine provide 96 hours of air, food and water. 
Guidelines and Legislation for Rescue Chambers in Coal Mines.
U. S. Federal Mine Safety And Health Act.
"EMERGENCY SHELTERS": SEC. 315. The Secretary or an authorized representative of the Secretary may prescribe in any coal mine that rescue chambers, properly sealed and ventilated, be erected at suitable locations in the mine to which persons may go in case of an emergency for protection against hazards. Such chambers shall be properly equipped with first aid materials, an adequate supply of air and self-contained breathing equipment, an independent communication system to the surface, and proper accommodations for the persons while awaiting rescue, and such other equipment as the Secretary may require. A plan for the erection, maintenance, and revisions of such chambers and the training of the miners in their proper use shall be submitted by the operator to the Secretary for his approval.
Mine Safety and Health Administration, 2008, 30 CFR Parts 7 and 75 Refuge Alternatives for Underground Coal Mines; Final Rule https://www.gpo.gov/fdsys/pkg/FR-2013-08-08/pdf/2013-19028.pdf
NORMA Official Mexicana, 2012, NORMA Official Mexicana NOM-023-STPS-2012, Underground Mines and Opencast Mines – Conditions of Security and Health at Work http://www.stps.gob.mx/bp/secciones/dgsst/normatividad/normas/Nom-023.pdf
Ministry of Energy and Mines, 2010, Decreto Supremo que aprueba el Reglamento de Seguridad y Salud Ocupacional y otras medidas complementarias en minería http://www.minem.gob.pe/minem/archivos/file/Mineria/LEGISLACION/2010/AGOSTO/DS%20055-2010–EM.pdf