Field Studies on Biological Agents

BAuA’s "Biological Agents" unit conducts research and development work on the subject of occupational safety and health, supports the transfer of knowledge to the practical level and advises political actors. In this respect, field research is a key pacesetter and a binding link.

The Federal Institute for Occupational Safety and Health (BAuA) carries out epidemiological studies to research health risks at workplaces.

Composting plants

In 1996, the world's first long-term study into composting plants began. The goal of the research was to examine the impact of bioaerosols on the health of current and former employees at composting plants over a time frame of 12 to 13 years. The study also addressed the occupational safety measures in use at individual composting plants. A key finding of the study: extended exposure to bioaerosols in composting plants increases the risk of chronic coughs and mucosal irritation.

It was not possible to prove that the (sometimes) high exposure to bioaerosols led to limitations in lung functioning or allergies to mould fungi among those working at the composting plants who were examined, however. Former employees had the highest rates of sensitisation. This finding can be explained by the "healthy worker survivor effect". This means that employees stay in an occupation for a long time as long as their health remains unaffected by their occupational exposure to possible hazards.

Factory farming of poultry

In the area of poultry farming, activities involving direct contact with animals lead to high rates of exposure to airborne biological agents. The result: a high prevalence of obstructive respiratory diseases.

The decline in lung functioning values during a working shift is a reversible symptom which can, however, lead to the chronic obstruction of the airways over time. This parameter proved useful on a preventive basis in the documentation of stress placed on employees with high rates of exposure.

None of the currently used standardised measurement parameters for airborne biological agents demonstrated a correlation with stress responses at different workplaces. At exposed workplaces, however, the values for inhalable dust (E-dust) and endotoxins correlated with the findings for the airways. Therefore, these are possible parameters for determining the effectiveness of technical protection measures.

Based on employees’ stress reactions, it is possible to recommend a variety of respiratory protection measures:

  • Ventilation technology for the manual sorting of chicks in hatcheries
  • FFP2 masks for activities with short term exposure and moderate physical exertion, such as bringing hay into stables, animal inoculation and cleaning work
  • Ventilated helmets for physically demanding activities involving direct contact with animals, such as the processing of animals at abattoirs and the capturing of animals

The effectiveness of ventilated helmets was confirmed because the lung functioning values were not found to decline. Due to their lack of airway resistance, they were accepted more readily by the workers than the masks.


In recent years, BAuA has conducted systematic research into the exposure of employees to health hazards in different areas of the recycling industry. Subsequent to detailed workplace measurements, the researchers found that employees were exposed to both hazardous substances and biological agents during the recycling of plastics, textiles and paper. Employees are exposed to airborne dusts in every area of the recycling industry. During the recycling of waste plastics, textiles and paper, high rates of exposure to biological agents were sometimes determined. With the participation of the federal states and the employer's liability insurance associations, BAuA has compiled guidelines for good working practice for all of the studied sectors.

Biogas plants

The production of renewable energy is a modern, rapidly developing economic sector. In a current project, BAuA is examining the exposure to biological agents during the production of methane in biogas plants designed especially for this purpose. In a current research project, our work group has collected representative data for an exposure assessment in comparison with biological agents.

Poultry- and pig rearing facilities

In a shared project with the State Agency for Nature, Environment and Consumer Protection of North Rhine Westphalia (LANUV NRW), BAuA has completed an intensive examination into the air quality at ten poultry and pig rearing facilities for the first time. The detected bacteria mainly consisted of representatives of risk group 1 and, on some occasions, representatives of risk group 2. The research will now focus on the extent to which these bacteria are relevant to the evaluation of bioaerosol exposures. On the whole, the molecular biological research confirms that the air contains highly complex mixes of different species of bacteria. It is not possible to make a definitive statement on the characteristics of the majority of the species of airborne bacteria, as their detection has only so far been possible on the basis of molecular biological methods.

The research projects frequently succeed in isolating biological agents for which no scientific description has yet been made. Efforts are under way to provide new descriptions of isolates of this kind so that they can be taken into account in future classification work.