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Underestimated danger: legionella in aerosols from cooling towers

Symbol picture: Michael Kauffmann - Eigenes Werk, CC BY 2.0 de,

In late summer 2023, there was a major outbreak of legionellosis in the city of Wuppertal (North Rhine-Westphalia). 13 people fell ill with the dangerous bacteriosis. The cases of illness were spread throughout the city and those responsible were unable to identify a common source of the disease, such as a contaminated shower system.


The possibility of the legionella being spread via aerosols from a cooling or air conditioning system was therefore also considered. All operators were instructed to immediately check and subsequently disinfect their systems. The operating logs were also inspected to record whether the systems were being checked weekly in accordance with the regulations.


Cooling towers contaminated with legionella can cause infections within a radius of over 10 kilometres, depending on wind conditions. Rapid tests for legionella could significantly improve the safety of such systems.


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