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Topics: Legionnella

Introduction:

Legionnaires' disease is a type of pneumonia, caused by the bacteria Legionella Pneumophillia. People catch legionnaires' disease by inhaling small droplets of water suspended in the air (aerosol), which contain the bacteria. The bacteria is acquatic in nature. Certain conditions increase the risk from Legionella:

  • suitable temperature for growth, 20ºC to 45ºC
  • a source of nutrients for the organism, eg sludge, scale, rust , algae, and other organic material; and
  • a way of creating and spreading breathable droplets, eg the aerosol created by a cooling tower or a spa pool.

Experience has shown that cooling towers, evaporative condensers and hot and cold water systems in a wide variety of work places present a risk of exposure to Legionella bacteria. The control of the organism and minimisation of aerosol are key in the management of the risk from Legionella bacteria.

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Key Issues:

  • Approved Code of Practice

    The Approved Code of Practice and Guidance "Legionnaires’ disease – The control of legionella in water systems" - L8 contains practical advice concerning the risk from exposure as aligned to the requirements of both the Health and Safety at Work etc Act 1974 and the Control of Substances Hazardous to Health 1999. The Approved Code also gives guidance on compliance with relevant parts of the Management of Health and Safety at Work Regulations 1999.

    Part 1 covers general safety issues, such as the identification, assessment, prevention or control and management of the risk, plus matters of training and competence and good record keeping. Part 2 reflects more precise issues, including control of the bacteria in water or cooling systems, management of cooling towers, treatment programmes, monitoring, cleaning and disinfection, hot and cold water services and matters relating to system design and construction.

  • Guidance Note

    The maintenance of a water system in a clean state is an important part of managing the risk from legionella. The removal of pack from a cooling tower for assessment of cleanliness as part of a cleaning regime is an issue which causes confusion and conflict for cooling tower users, water treatment companies, other service providers and inspectors of health and safety.

    The "Removal of Pack from Cooling Towers" HSE guidance note aims to clarify the guidance given in L8 and promote a consistency of approach to the need for removal of pack by providing advice on the factors which may inform decisions on pack removal for cleaning and inspection.

    Futher resources can also be downloaded from

Key Legislation

Control of Substances Hazardous to Health Regulations (Northern Ireland) 2003

Please note that these links are to the original legislation, visitors should verify for themselves whether legislation is in force or whether it has been amended or repealed by subsequent legislation.