30 CFR § 57.5061
(a) MSHA will use a single sample collected and analyzed by the
Secretary in accordance with the requirements of this section as an
adequate basis for a determination of noncompliance with the DPM limit.
(b) The Secretary will collect samples of DPM by using a respirable
dust sampler equipped with a submicrometer impactor and analyze the
samples for the amount of elemental carbon using the method described
in NIOSH Analytical Method 5040, except that the Secretary also may use
any methods of collection and analysis subsequently determined by NIOSH
to provide equal or improved accuracy for the measurement of DPM.
(c) The Secretary will use full-shift personal sampling for