1. Microbiological examination of water and aerosols from four industrial evaporative cooling systems in regard to risk of Legionella emissions and methodological suggestions for surveillance
- Author
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Oliver Sperber, Andreas Nocker, Jan Frösler, Lorenz Schulte-Illingheim, Laura Welp, and Achim Hugo
- Subjects
Legionella ,Chemie ,010501 environmental sciences ,Risk Assessment ,01 natural sciences ,Legionella pneumophila ,Bioburden ,03 medical and health sciences ,0302 clinical medicine ,Water cooling ,Industry ,Air Conditioning ,030212 general & internal medicine ,Health risk ,0105 earth and related environmental sciences ,Aerosols ,Air Pollutants ,biology ,Public Health, Environmental and Occupational Health ,Environmental engineering ,biology.organism_classification ,Aerosol ,Environmental science ,Water Microbiology ,Risk assessment ,Environmental Monitoring ,Evaporative cooler - Abstract
The hygienic risk associated with evaporative cooling systems in Germany is currently only assessed by determining concentrations of Legionella spp. in the corresponding cooling waters. Relevant for the health risk is however the load of Legionella in emitted aerosols. In this work aerosol emissions from four industrial cooling systems (A - D) were analyzed. A microbiological air bioburden factor (MABF) is suggested to be useful to assess the overall microbiological load of emitted air and to judge the efficiency of droplet separation and overall microbiological retention. Whereas the MABF by itself only serves as a technical quality assurance (QA) parameter, the hygienic relevance has to be seen in combination with the assessment of Legionella either contained in the aerosol or in the cooling water. Plate counting of colonies was an appropriate method to quantify Legionella spp. in aerosols given the short time of flight at the chosen sampling locations and resulting low risk of desiccation. qPCR data on the other hand proved more reproducible than the culture approach to quantify Legionella spp. concentrations in cooling water-. The application of qPCR also allowed to assess the relative proportion of Legionella pneumophila within the total pool of Legionella which adds epidemiological relevance to risk assessment. A traffic light system was proposed to guide interpretation of qPCR data. The four industrial systems greatly differed in all measured parameters leading to different associated risks.
- Published
- 2020