DETERMINATION OF CRYSTALLINE SILICA AND OTHER MATERIAL DUSTS IN AIR

摘要

According to the invention crystalline silica in the form of particles finer than 10 microns (respirable dust) in air, such as mine atmospheres, is determined by removing from the air particulate matter larger than 10 microns and then passing the air through a membrane filter to collect the residual particulate matter including respirable dust, if any. The filter with its adherent dust provides an analytical sample which is placed in one beam of a double-beam infrared spectrophotometer; an unused, clean membrane filter of the same material and size is placed in the other beam of the spectrophotometer as a reference, and the two beams are subjected to infrared radiation to produce a spectrum of the dust on the sample filter. The presence of respirable crystalline silica is shown qualitatively by the presence of twin peaks of the spectrum at 12.52, 12.82 microns.