Laboratory Calibration of a Technique for Determination of Respirable Quartz in Mine Air

Samples taken by a Casella personal respirable dust sampler in a cloud of pure quartz dust in the laboratory dust chamber were examined by x-ray diffraction using molybdenum and copper Kα radiations with step scanning. A calibration of this system was obtained with respirable dust quantities on the filter of 0.04 to 3 mg. There was a decrease in the factors relating peak height or peak area to mass of quartz at low quantities of quartz, presumably due partly to penetration into the rather coarse (5-µm pore size) silver membrane used and to shadowing by the roughness of the silver membrane. Calibrations were also performed with samples prepared by Leroux's technique of elutriation and collection on a filter. These resulted in x-ray intensities 25% lower than those of the samples prepared in the dust chamber. This technique was tested in some Ontario hard rock mines and in Nova Scotia coal mines. The technique is sensitive enough to detect respirable quartz dust concentrations of 0.01 mg/m3 on shift period samples. However, interference from mica has been found in a number of samples.