In its latest hazard alert, the US Mine Safety and Health Administration identified a confined space as an area with poor or no airflow and warned the lack of air created dangerous gas accumulations.

“Before a miner enters a confined space, the atmosphere needs to be checked for adequate oxygen concentration and the accumulation of flammable or harmful gases,” the agency said.

MSHA also stressed the presence and maintenance of adequate ventilation during welding or cutting, both of which deplete oxygen and produce carbon monoxide and other harmful gases.

Painting, chemical use and other tasks may require proper ventilation along with the use of personal protective equipment such as respirators, goggles, face shields and other special protective clothing.

Atmospheric monitoring should be used, and mines should ensure the calibration of instruments to ensure a safe working atmosphere.

“Monitoring should be conducted prior to entering a confined work space and continuously until the space is exited,” MSHA said, adding that oxygen, and all potentially toxic and explosive gases should be checked for in the confined space.

Finally, miners working in a confined space should be attached to a lifeline, with a second person positioned outside the space to constantly monitor the lifeline and miner.

That individual can then be ready to summon help in an emergency. They should never enter the space for the rescue of a collapsed miner without wearing appropriate safety and PPE.

For more information on the hazards of working on confined spaces, visit the MSHA web site.