 2 Coal Mine explosion in 1994  where the need for a communication system to survive major incidents underground was identified in the inquiries into the disasters.PED is a one-way text paging device, with wide use in Australia, as well as installations in the United States, China, Canada, Mongolia, Chile, Tanzania, and Sweden.Australian company Mine Site Technologies began the development of PED in 1987, and it became commercially available and Mine Safety & Health Administration (MSHA) approved in 1991.