Home gardeners are encouraged to wear a face mask and gloves while handling potting mix and compost, and to wash their hands thoroughly, to avoid contracting Legionnaires' disease.

Legionella longbeachae bacteria is often found in potting mix and can cause the lung infection Legionnaires' disease if someone inhales dust from contaminated soil.

NSW Health Executive Director, Dr Jeremy McAnulty, said gardeners can take simple precautions to ensure they are safe when gardening.

''Most people who breathe in the bacteria don't become ill, but the risk of infection increases if you're older, a smoker, or have a weakened immune system," Dr McAnulty said.

"Wetting the potting mix first also helps prevent any contaminated potting mix dust blowing up into the air and being inhaled.

"Even if you've been wearing gloves, make sure to wash your hands thoroughly with soap before eating or drinking as the bacteria could still be there."

There were 96 cases of Legionnaires' disease so far this year from the type of bacteria that can be found in potting mix and soils in NSW, and 106 were reported last year. Sadly, a woman in her 60s died from the disease in Sydney this week.

Symptoms of Legionnaires' disease can develop up to 10 days after exposure to the bacteria.

Symptoms include fever, chills, a cough, shortness of breath, aching muscles, headache, tiredness, loss of appetite and diarrhoea.

Legionella bacteria can multiply in bagged potting mix, mulch and other soil products. To minimise the risk, people should always read and follow the manufacturer's warnings on the outside of the bag.

"Put on a face mask and wear gardening gloves before you open the bag of potting mix and handle the contents," Dr McAnulty said.

A more common source of Legionnaires' disease is due to a different strain of bacteria, usually found in contaminated air conditioning cooling systems on large buildings.

If you have ongoing or worsening symptoms, you should see your doctor or visit your local emergency department.

For more information on visit Legionnaires' disease.