At the request of the Mine Safety and Health Administration (MSHA) and the West Virginia Office of Miners' Health, Safety, and Training (WVOMHS&T), the National Institute for Occupational Safety and Health's (NIOSH) Pittsburgh Research Laboratory (PRL) evaluated the effects of explosions on specific mine ventilation seals at its Lake Lynn Experimental Mine (LLEM) to assist the agencies in their investigations of the explosion at the Sago Mine in West Virginia, which occurred on January 2, 2006, and resulted in 12 fatalities. Six full-scale explosion tests were conducted in the LLEM from April to October 2006 to help answer questions regarding possible scenarios for the Sago explosion. The protocols for these tests, and in particular the procedures for constructing various Omega block seals, were developed mainly by MSHA and WVOMHS&T. NIOSH developed the experimental procedures at the LLEM that would provide the required range of explosion pressures against the seals. NIOSH also documented the seal construction, determined and installed the appropriate instrumentation, conducted the explosion tests, analyzed the data, and photographically documented the postexplosion observations. By comparing the results of known explosion loading pressures on the various ventilation structures and objects in the LLEM with their observations at the Sago Mine, MSHA and WVOMHS&T could better analyze the explosion pressures that may have occurred at the Sago Mine.