Determination of the collection efficiency of a microbial air sampler

The Biotest RCS Plus air sampler was compared with the well‐established Casella slit sampler for the quantitative analysis of the microbiological content of air. The results of the tests reported here show that the RCS Plus sampling efficiency is similar to that of the Casella sampler over the range of particles likely to be encountered in the environment. For particles less than 4 μm down to the sub‐micronic sizes the efficiency of sampling falls off only gradually so that the efficiency of sampling for 1·0 μm particles is only reduced to about 50%. The ability to pre‐select 10 different volumes (from 1 to 1000 1) enables the samplers to be used for measuring a wide range of concentrations of airborne micro‐organisms in a variety of locations.