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safe use of potting mixLegionnaires' disease is a serious and potentially life threatening lung infection that is caused by the bacteria Legionella.

The most common species associated with causing human disease in Australia are Legionella pneumophila and Legionella longbeachae.

Legionella pneumophila

Legionella pneumophila can be transmitted through the air by inhaling fine droplets of water contaminated with the organism, and are associated with warm water environments such as:

  • cooling towers
  • evaporative air-conditioners
  • showers
  • warm water systems
  • spa pools
  • misting or droplets sprays and
  • fountains

Legionella longbeachae

Legionella longbeachae Is the most common strain in Western Australia and is associated with breathing in aerosols from:

  • potting mixes
  • gardening soils
  • mulches
  • composts and
  • soil conditioners


The early symptoms of Legionnaires' disease are often like a severe ‘flu’ infection, and include some or all of the following symptoms:

  • Fever (up to 40ºC)
  • Chills, aching muscles and joints
  • A dry cough
  • Headache (often severe)
  • Tiredness
  • Loss of appetite
  • Shortness of breath

Who is most at risk of Legionella infections?

Legionella infections are more common in the middle aged and older persons and those whose immune system is weak. Men are affected more commonly then women.

Factors that increase your risk include:

  • Smoking
  • Lung disease
  • Diabetes
  • HIV/Aids
  • Cancer
  • Steroid use or other immunosuppressive medication
  • Renal disease
  • Being over 50 years of age
  • Excess alcohol consumption.

These conditions lower a person’s resistance (immune system) to this disease. Young and healthy people rarely get a Legionella infection.

How can I minimise my risk of getting a Legionella infection around the home?

There are a few simple things you can do around the home to avoid or prevent conditions that allow Legionella to grow to high levels.

When using potting mixes and gardening soils

Potting mixes, composts, mulches, soil conditioners and gardening soils can be harmful to your health if you do not take some simple precautions. This includes bagged material and soils purchased in bulk form (e.g. trailer load of mulch).

Simple precautions should be followed when handling such materials:

1. Always wear gloves

2. Wear a face mask to help avoid inhaling aerosols

3. Open bagged material with care to avoid inhaling aerosols

4. Keep the mix damp while in use

5. Wash your hands thoroughly after use

6. Store potting mix in a cool place, out of the sun

Read the Legionnaires Disease (PDF 222KB)  fact sheet for further information.


Fact sheets

 For further information contact the Environmental Health Directorate on (08) 9388 4999 or email

Last Updated: 3 September 2010

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