Several years ago, the Mine Safety and Health Administration (MSHA) proposed changing the metal/nonmetal dust limit from a 10-mg/m3 total nuisance dust standard to a 5-mg/m3 respirable dust standard. Discussions with the Portland Cement Association and a number of member companies were held to determine the potential impact this change could have on the industry. Shortly after these discussions, a study was initiated by the then-Bureau of Mines to provide insight into typical respirable dust levels at these operations. In addition, researchers wanted to examine the potential impact that the new dust standard would have on the Portland cement industry. Once typical respirable dust levels were determined, recommendations would be given on ways to lower dust concentrations in cement operations and lower the dust exposure of workers

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