There are no universally accepted criteria for assessing exposure to harmful biological agents (HBAs). When a group of workers is suspected of being exposed to one or more HBAs capable of causing disease or responsible for adverse symptoms, the validity of that suspicion must be confirmed by:

• detecting the agent in the work environment and determining the scale of exposure;
• direct identification of the biological agent in the body, most often by the culture of the clinical material (blood, urine, feces, sputum, throat swab, nasal lavage, cerebrospinal fluid, lymph node aspirate, etc.) on appropriate culture media, less commonly by preparing a microscopic specimen, injecting clinical material into experimental animals, or using highly sensitive genetic methods such as Polymerase Chain Reaction (PCR);
• indirect methods based on assessing the organism's immune reaction to the agent's antigens (this is important in identifying both infectious and allergic agents), most often by serological testing (blood serum samples) with an enzyme-linked immunosorbent assay (ELISA), agglutination, gel precipitation or radioimmunoabsorption (RAST).

Compared to other aerosols, bioaerosols require special sampling procedures. Traditional sampling (filtration, impaction, impingement) and cultivation methods are designed to assess viable components of microorganisms such as fungal conidia or bacterial vegetative cells or bacterial spores. These methods dismiss the microorganisms and their fragments incapable of growth and colony formation (so-called non-culturable) and non-viable microorganisms. The consequence of measuring only a small fraction of the particles present in a given environment is an obvious underestimation of the real-world exposure caused by microbiological agents.

Bioaerosol testing is of key importance in detecting the presence of biological agents in the work environment and determining the extent of exposure. In such cases, microbiological analysis of settled dust, raw materials (e.g. grain, hay), soil, waste, compost, fertilizers, sewage, water and plant samples, as well as swabs from walls, floors and furniture may also prove important. In the laboratory elaboration of samples, the method of plate dilution is most often used, which consists in sowing a series of dilutions of a given sample on an agar medium. Samples can also be tested for the presence of endotoxins (Limulus test), mycotoxins (chromatographic methods) or specific microorganisms (microscopic examination). If a zoonotic disease is suspected, clinical material (blood, urine, feces, milk, tissue fragments, skin scrapings, etc.) should be collected from the animals and tested in accordance with generally accepted microbiological methodology.