Performance of bioaerosol samplers used by the UK biotechnology industry

The quantitative assessment of bioaerosols is important in a number of indu strial and health-care applications. Measurements to aid the control of air borne infection in hospitals, detection of the release of potentially harmf ul microorganisms from bio-processing equipment and monitoring the exposure of workers and animals to bioaerosols are examples of situations where dif ferent concentrations of microorganisms and varying ambient conditions may be expected. Microorganisms are notoriously difficult to assess accurately under such variable conditions and no single assay method is suitable for a il applications; rather the method needs to be tailored to the application of interest. Problems are compounded by the differences in assay method (su ch as the type of media used for culturable counts) or sampler type selecte d, making the interpretation of the results difficult. An understanding of the airborne behaviour of microorganisms over a range of environmental cond itions is vital if procedures are to be defined and recommended for the han dling, sampling and assessment of bioaerosols. Microorganisms that are robu st over a wide range of conditions are ideal as tracer particles. Unfortuna tely, the large majority of non-fungal bioaerosols are susceptible to damag e. A predictable sampling procedure is required which will not affect the v iability of the collected sample. Studies, reported on the development of p rocedures to characterise airborne biological particles, included tests car ried out under controlled environmental conditions to compare the performan ce of five industrially important bioaerosol samplers with that of a refere nce glass wet-walled, cyclone sampler, using test aerosols of Saccharomyces cerevisiae cells and Penicillium expansum spores. The samplers tested were Andersen Microbial Sampler, Biotest RCS, Biotest RCS Plus, MicroBio MB1, a nd MicroBio MB2. The cyclone sampler, Andersen Microbial Sampler and the Mi croBio MB1 and MB2 meet the basic criteria for a suitable reference sampler , except that the last three systems do not provide total counts. It will b e important to investigate in the future how well they perform under the ch allenge of "real-life" conditions. (C) 1999 Elsevier Science Ltd. All right s reserved.