DETERMINATION OF DUST CONCENTRATIONIN THE AIR BY SCATTERED LIGHT

The circuit, in which the photoelectric current of photomultiplier was transformed to digital amount, was developed. This A-D transformation circuit is very simple and has a high sensitivity. The photoelectric current of 5 × 10-4 μA is transformed into one pulse per minute by this circuit. Three kinds of apparatus for the determination of aerosol concentration were devised by means of measuring the intensity of scattered light by this circuit.Responses of these devices are linearly proportional to dust concentration in the same aerosol systems.These apparatus can measure the concentration of the order of 10-3mg/m3 of quartz dust. Significance of dust determination by these devices was also disscussed.