Abstract
A new type of aerosol sampler that collects airborne particles in several categories of decreasing particle size is described and procedures for its operation are given. Experimental studies with the instrument showed that, (a) wall loss is negligible, (b) there is no slippage of bacterial particles, (c) the instrument is extremely sensitive and (d) particle size discrimation makes it possible to determine the particle size spectrum of bacterial aerosols. It is also suggested that the sampler provides a suitable means of assessing the health hazard in particulate air pollution.