Photometric Determination of Respirable Dust Concentration without Elutriation of coarse particles

Abstract

Abstract The principle of an instantaneous reading, respirable dust, photometer and its application are described. The instrument measures the infrared light (940 nm wavelength) scattered on airborne particles under a mean scattering angle of 70°. Its open measuring chamber, which is insensitive to daylight, is filled with total dust. The photometer reading, however, is calibrated in terms of mass concentration of respirable dust by means of a gravimetric respirable dust sampler. Experiments carried out with monodisperse test aerosols and with real dusts confirm the instrument's principle. The photometer values obtained for real dusts can be linearly converted into mass values of respirable dust as long as ultra‐fine or ultra‐coarse dusts are excluded. In several practical cases an increased flux of scattered light is compensated for by a higher density of the dust material.