Legionella control in evaporative cooling systems

Evaporative cooling systems, such as cooling towers and evaporative condensers, are susceptible to colonisation by Legionella bacteria. Previous evidence has demonstrated that they can be responsible for sporadic outbreaks of infection, ranging in scale both in terms of numbers infected and severity. When such outbreaks occur, they frequently infect members of the public rather than workers and, in many cases, are a source of major public health concern.

Between 1 April 2013 and 31 August 2014, the Health and Safety Executive (HSE) inspected 1,906 premises with evaporative cooling systems. While the majority of sites required no enforcement, material breaches were found at 625 sites, 33% of those inspected, including 409 Improvement Notices (INs) and 12 Prohibition Notices (PNs) served at 229 sites, 12.0% of those inspected.

A recently published HSE Research Report analyses the underlying causes of breaches of health and safety compliance. The main ones were:

• lack of training
• failure to maintain the cleanliness of cooling towers and the water within them
• absence of, or inadequate, risk assessments
• absence of, or insufficiently detailed, written control schemes

Further analysis looked into the reasons why cooling towers were not cleaned properly.

HSE considers that these results provide a valuable resource which can be used to focus future strategies to improve duty-holder compliance.

Source: HSE, March 2018