AIR SAMPLING INSTRUMENTATION.

The selection of the air-sampling method depends on the physical and chemical characteristics of the air contaminant. In selecting sampling equipment, factors to be considered include the particulate sizes of dusts involved; and for gases and vapors, the density, solubility, vapor pressure, freezing point, and chemical stability. Other considerations include the presence of other substances that can interfere with either the collection or chemical analysis of contaminant under investigation. It may be necessary to collect samples through a number of different methods to determine the concentrations in a mixture of the contaminants. The factors to be considered in the proper choice of a particular measurement device are: sensitivity and accuracy of the instrument or procedure; reliability of instrument under various conditions of use; type of information required.