Legionnaires' disease

Revision as of 08:02, 2 November 2014

Legionnaires’ disease is the most serious of a number of disease that can be caused by legionella bacteria. It is generally contracted by inhaling water droplets suspended in the air.

Legionnaires’ disease is a form of pneumonia that can be fatal, in particular for older people, people who smoke, heavy drinkers, and people with impaired immunity, and people with illnesses such as chronic respiratory disease, kidney disease, diabetes, lung disease, or heart disease.

Legionella is commonly found in rivers, lakes and reservoirs, but its presence is limited and rarely causes legionnaires' disease. However, it can multiply in systems such as in cooling towers, evaporative condensers, hot and cold water systems, spa pools and other plant and systems containing where there may be a risk during operation or maintenance, where:

• The water temperature is between 20 and 45 °C.
• Water droplets can be produced and dispersed.
• Water is stored or re-circulated.
• Deposits such as rust, sludge, scale, organic matter and biofilms are present that can support bacterial growth.

Measures must be introduced in these systems to prevent or control the risk of legionella by:

• Controlling the release of water spray.
• Avoiding temperatures likely to permit the growth of legionella;
• Ensuring water cannot stagnate.
• Avoiding materials that permit the growth of legionella.
• Ensuring that systems and water are clean.
• Treating water.

The legal framework for the control of legionella is established by:

• The Health and Safety at Work etc Act.
• The Control of Substances Hazardous to Health Regulations (COSHH).
• Management of Health and Safety at Work Regulations.
• The Reporting of Injuries, Diseases and Dangerous Occurrences Regulations (RIDDOR).
• The Safety Representatives and Safety Committees Regulations.
• Health and Safety (Consultation with Employees) Regulations.

The Health and Safety Executive has published, and approved code of practice (ACOP) Legionnaires’ disease: The control of Legionella bacteria in water systems^[1] , and measures adopted must be at least as effective as those that it describes. The approved code of practice applies to ‘premises controlled in connection with a trade, business or other undertaking where water is used or stored; and where there is a means of creating and transmitting water droplets (aerosols) which may be inhaled, causing a reasonably foreseeable risk of exposure to legionella bacteria.’

It sets out the responsibilities for employers and with people with responsibilities for the control of premises such as landlords (dutyholders).

Dutyholders should take suitable precautions to prevent or control the risk of exposure to legionella, including:

• Identifying and assessing sources of risk.
• Where necessary, preparing a written scheme for preventing or controlling the risk.
• Implementing, managing and monitoring precautions.
• Keeping records of the precautions taken.
• Appointing a competent person to help take the measures needed.

Find out more

Related articles in Designing Buildings Wiki

• Cooling.
• Cooling tower.
• Design risk assessment.
• Evaporative cooling.
• Health and safety Executive.
• Health and safety.

External references.

• Legionnaires’ disease: The control of Legionella bacteria in water systems.
• Legionnaires' disease: a brief guide for duty holders.
• HSE, Legionella and Legionnaires' disease.