Research has shown conclusively that as the average size of coal
dust particles decreases, the explosion hazard increases (Cybulski,
1975; Michelis, 1998; Cain, 2003; NIOSH, 2010). Recent dust survey
results show that the coal dust found in mines today is much
finer than in mines of the 1920s (Sapko et al., 2007). Given the
results of the recent coal dust particle size survey and subsequent
full-scale Lake Lynn Experimental Mine (LLEM) explosion tests, the
National Institute for Occupational Safety and Health (NIOSH)
recommended a new standard of 80% total incombustible content
(TIC) be required in the intake airways of bituminous coal mines to
replace the existing 65% TIC requirement (NIOSH, 2010). To determine
compliance with the 80% TIC requirement, mine operators
and MSHA inspectors regularly collect dust mixtures at various
distances along mine entries, measure the TIC, and compare the
results to the minimum 80% TIC requirement. The sampling method
of collecting a combined band sample using a brush and pan to
gather an approximately 15-cm (6-in) wide strip of dust from the