Legionella and the Control of Legionnaires' disease
Legionnaires' Disease is a potentially fatal form of pneumonia which can affect anybody, but which principally affects those who are susceptible because of age, illness, immunosuppression, smoking etc. Legionella Control forms part of legislation imposed upon a dutyholder
It is caused by the bacterium Legionella pneumophila and related bacteria that can be found naturally in environmental water sources such as rivers, lakes and reservoirs, usually in low numbers. As they are commonly found in environmental sources they may also be found in purpose built water systems such as cooling towers, evaporative condensers and whirlpool spas.
If conditions are favourable the bacterium may grow creating conditions in which the risk from legionnaires' disease is increased. It is therefore important to control the risks by introducing measures outlined in the Approved Code of Practice & guidance document
How do people get legionnaires′ disease?
The agent that causes Legionnaires' disease is a bacterium called Legionella pneumophilia. People catch Legionnaires' disease by inhaling small droplets of water suspended in the air, which contain the bacteria.
Certain conditions increase the risk from legionella:
- A suitable temperature for growth, 20 to 45°C
- A source of nutrients for the organism, eg sludge, scale, rust, algae, and other organic matter
- A way of creating and spreading breathable droplets, eg the aerosol created by a cooling tower or spa pool
Measures to control legionella
To prevent exposure to the legionella bacteria, you as a dutyholder must comply with legislation that requires you to control, manage, maintain and treat water systems in your premises properly. This will include, but not be limited to, appropriate water treatment and cleaning regimes.
Remember, legionella can grow in any workplace if the conditions are right - you do not have to work with microbiological agents, eg in a laboratory, for exposure to occur. If you are responsible for any of the water systems described in HSE's Approved Code of Practice (ACoP) and Guidance "Legionnaires' disease: To implement legionella control of bacteria in water systems" (L8) you will need to assess the risk of employees and others in the workplace contracting Legionnaires' disease.
Copies of L8 can be purchased from HSE Books. HSE also publishes several free leaflets and a video explaining legal duties and the control of legionella in cooling systems and hot/cold water systems available from HSE Books.
Separate regulations (The Notification of Cooling Towers and Evaporative Condensers Regulations 1992) require the notification of cooling towers to your Local Authority (contact them directly for further information)