This test method covers the apparatus required, sampling methods, standard procedures and calculations, and test reports for counting and sizing airborne microparticulate matter, the sampling areas for which are specifically those with contamination levels typical of cleanrooms and dust-controlled areas. The test method is based on the microscopical examination of particles impinged upon a membrane filter with the aid of a vacuum. Sampling may be done in a cleanroom, clean zone, or other controlle areas, or in a duct or pipe, wherein the number of sampling points is proportional to the floor area of the enclosure to be checked. The apparatus and facilities required are typical of a laboratory for the study of macroparticle contamination. The operator must have adequate basic training in microscopy and the techniques of particle sizing and counting.