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 aquatic 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
- 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.