Assessment of the Suitability of Different Substrate Materials for Bioaerosol Sampling

Abstract

Bioaerosols may comprise infectious, allergenic and microbial particles. A range of static bioaerosol sampling methods currently exist and are described in detail by Crook (1996). Most of these aim to collect the sample in a viable, culturable state so that an estimate of the bioaerosol concentration may be made by counting the number of colonies that develop on agar growth media. The majority of these methods are poorly characterised, either in terms of their physical sampling efficiency, or in terms of the recovery and survival rates of collected microorganisms. Personal sampling for bioaerosols is generally carried out using standard aerosol samplers that collect the aerosol onto a filter. The dehydration effects caused by this method can greatly reduce the viability of the more delicate micro-organisms, especially bacteria. This is not problematic where the analysis of bioaerosol concentrations is carried out on both living and dead cells using direct counting by microscopy, biochemical or molecular detection methods. In some instances however, culturing is necessary, either to aid species identification (in the case of allergenic organisms) or to demonstrate the viability of pathogens. Existing samplers therefore have a number of disadvantages when used to assess health risks to workers arising from exposure to airborne micro-organisms. A rational, scientifically-based scheme for assessing bioaerosol exposures requires a personal sampler with the following characteristics: