Andrews Sykes Air Conditioning Services – Good Practice Notes: Legionnaires’ Disease

One year on from  outbreaks in Edinburgh and Stoke-On-Trent, Legionnaires’ disease, whilst increasingly less common, remains a potential issue for building owners, facilities managers and occupiers – especially in commercial and public buildings

Legionellosis is an infection caused by a bacterium named Legionella Pneumophila. Legionella are natural inhabitants of water and can be detected in rivers, lakes and streams.


Patients with Legionnaires disease usually have fever, chills and a cough. Some patients have muscle aches, headache, tiredness and loss of appetite. Chest x-rays will often look like pneumonia, even to the trained eye, therefore it is difficult to distinguish Legionnaires disease from other types of pneumonia by symptoms alone.

People of any age may get Legionnaires disease, but middle aged or older people, smokers, those with chronic lung disease or people with a lowered immune system are more susceptible.

The most common method of contracting Legionnaires disease is by inhaling droplets in the form of mists from a water source contaminated with Legionella bacteria. The chain of events required for infection to take place includes:
• Conditions suited to the multiplication of the organism, i.e. water temperatures in the range 20ºC – 45ºC, low flow rates or standing water and the presence of sludge, scale, rust, algae and organic matter to provide nutrients.
• A means of creating breathable droplets.
• Contact with the droplets by a susceptible person. The disease cannot be passed from person to person.

The conditions described above can occur in building services equipment such as cooling towers, spas, showers fed from a hot water storage tank and humidifiers.

It is important to emphasise that the air conditioning systems installed and maintained by Andrews Air Conditioning Services carry no risk of harbouring legionella bacteria, as we specialise in the use of air-cooled refrigerant air conditioning systems, which do not create the environmental conditions required by the legionella bacterium. For more information please go to our website Legionnaires’ Disease – The Facts

For further information on the development of a safe and cost effective maintenance regime for your air conditioning visit