Respirable quartz: Geometric mean exposures and percent exceeding designated occupational exposure limits by MSHA coal mine district and state, MSHA inspector and mine operator samples, 1982–2003
- indicates incalculable field.PEL - permissible exposure limitREL - recommended exposure limitGM - geometric meanmg/m3 - milligrams per cubic meterMRE - Mining Research EstablishmentMSHA - Mine Safety and Health Administration * Samples selected based on the respirable dust level and MSHA PEL (2 mg/m3 MRE or adjusted PEL).
Note: The MSHA PEL is 2 mg/m3 MRE for respirable dust containing less than or equal to 5 percent quartz. The PEL is adjusted using the formula [(10 mg/m3 MRE) / (% quartz)] for respirable dust containing greater than 5 percent quartz. See appendices for source description and methods.
Source: MSHA coal mine inspector and mine operator quartz data.
