ABSTRACT
The separation of dust particles in thermal and electric fields for airborne dust measurement was accomplished by thermal and electrostatic precipitators. An important improvement in the field of dust sampling was provided by an instrument consisting of various impaction stages. The analytical procedures and equipment, such as gravimetry, titrations, colorimetry, photometry, polarography, X-ray diffraction, and others, were used for further chemical dust and aerosol analysis. The operation of aerosol centrifuges was similar in principle to the horizontal elutriators, with the force of gravity replaced by centrifugal force. Removing dust and aerosol particles from gases by filtering them through a suitable medium provides a simple means of sample collection. The membrane filters were used both to weigh collected dust and to count particles with an optical microscope. The dust was collected on the aluminum plate, which could be weighed.
