Procedures for the Development and Characterisation of Biological Particles
Airborne micro-organisms are notoriously difficult to enumerate accurately and no single procedure is suitable for all applications. The first aim of this study was to examine the effects of aerosolisation on micro-organisms with reference to post-sampling handling. Procedures were used to examine the effects that recovery agents added to the spray suspension prior to aerosolisation have on micro-organism culturability and to examine the effects of environmental factors (temperature, relative humidity and gaseous pollutants) on bioaerosol viability and survival.
The post-collection handling and storage are important factors in detemining culturable counts. The culturable fraction can vary with increasing collection fluid and spray suspension age. Out of five microorganisms (one virus, two bacteria and two fungi) tested for the effects of collected aerosol and spray suspension age, only Penicillium expansum spores had a constant culturable fraction. Therefore, recommending a particular microorganism (apart from P.expansum) as an airborne biological standard may not be a realistic proposition. It would be more sensible to select a microorganism that is representative of the envisaged application and characterise it in terms of the aerosolisation parameters, storage time and conditions.
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