Workers may be exposed to a range of bioaerosols in their work environment which present hazards of infection, allergy and toxicosis. To assess hazard and risk, workplace exposure to biological agents must be measured. Sampling strategies and methods must be relevant to workplace conditions to ensure samples are representative. For example, selection of an analytical method to measure airborne microorganisms depends on the information required and the numbers and types of microorganisms of interest. Methods for detecting large numbers of allergenic microorganisms are likely to differ from those for infectious or toxic organisms. Molecular techniques may complement current methods and provide alternatives to culturing. Crown