skip to content

Legionnaires’ disease is a potentially fatal form of pneumonia which everyone is susceptible to. There are similar but less serious conditions such as Pontiac fever and Lochgoilhead fever.

Where does it come from?

Legionella bacteria are found in natural water systems, e.g. rivers and ponds. The conditions are very rarely right for people to catch the disease from these sources. Outbreaks of Legionella normally occur from exposure to the bacteria in purpose-built systems where water is stored or used in conditions that encourage growth, e.g. hot and cold water systems, ventilation systems, cooling towers and evaporative condensers.

How do people contract it?

People contract Legionnaires’ disease by inhaling small droplets of water (aerosols), suspended in the air, containing the bacteria. Certain conditions increase the risk from legionella if:

  • the water temperature in all or some parts of the system is between 20-45 °C
  • there are deposits that support bacterial growth thereby providing a source of nutrients for the organism e.g. rust, sludge, scale, organic matter and biofilms
  • water is stored and/or re-circulated
  • breathable water droplets are formed into an aerosol and dispersed e.g. a shower

Who is at risk?

Everybody who is exposed to water is at risk, however some people are at higher risk than others. These groups are:

  • those who are over 45 years of age
  • those who smokers and drink heavily
  • those with an impaired immune system
  • those suffering from chronic respiratory or kidney disease
  • those with diabetes, lung and heart disease

If conditions are favourable, the bacteria may grow increasing the risks of Legionnaires’ disease and it is therefore important to control the risks by introducing appropriate measures.

How can the risk be minimised?

Under general health and safety law, Duty Holders including employers or those in control of premises, must ensure the health and safety of their employees or others who may be affected by their undertaking. They must take suitable precautions to prevent or control the risk of exposure to legionella. They also need to either understand, or appoint somebody competent who knows how to identify and assess sources of risk, manage those risks, prevent or control any risks, keep records and carry out any other legal duties they may have.