A.I.S.I. Beta attenuation Particulate monitor ( a step sampling device for collecting particulates on a strip of filter paper, with the measurement being made by a beta particle source and counter - the attenuation as a result of the mass of the particles is proportional to the mass, and the device is still available commercially) 1975 -1980. Made by Research Applicance Co., Allison Park, PA, USA (RAC logo) Beta attenuation particulate monitor, 1984 1984