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All coal mine respirable dust concentrations measured with approved personal respirable dust sampling instruments are converted to equivalent MRE sampler concentrations by multiplying by the factor 1.38. This conversion factor was determined from comparison measurements made in underground coal mine environments. This report describes the results of the Mine Safety and Health Administration's (MSHA) sampling of surface mining operations to determine if 1.38 is a valid factor for converting surface coal mine dust samples collected with approved personal samplers to equivalent MRE concentrations. Comparative measurements were obtained with the MRE and personal gravimetric dust samplers at a variety of surface mining operations and coal preparation plants. Regression analysis was used to derive a relationship between measurements obtained with the MRE and personal respirable dust samplers. The factor derived for surface measurements was within 9 percent of that derived for underground measurements. It was concluded that 1.38 is the most applicable factor to use for converting personal respirable dust measurements to equivalent MRE measurements. (ERA citation 08:045399)