Respirable coal mine dust: Geometric mean exposures and percent exceeding designated occupational exposure limits by type of mine, MSHA inspector and mine operator samples, 1979–2003
- indicates incalculable field.PEL - permissible exposure limit REL - recommended exposure limit GM - geometric mean mg/m3 - milligrams per cubic meterMRE - Mining Research EstablishmentMSHA - Mine Safety and Health Administration
Note: In coal mining, for respirable dust containing less than or equal to 5% quartz, the MSHA PEL is 2 mg/m3 MRE; for respirable dust containing greater than 5% quartz, the MSHA PEL is [(10 mg/m3 MRE) / (% quartz)]. The NIOSH REL of 1 mg/m3 MRE for respirable coal mine dust was adopted in September of 1995. Geometric means are reported in MRE equivalent. All samples are compared to the MSHA PEL of 2 mg/m3 MRE for respirable coal mine dust containing less than or equal to 5% quartz, regardless of actual quartz content. See appendices for source description, methods, and agents.
Source: MSHA coal mine inspector and mine operator dust data.