This fact sheet provides information on what mould is, how mould can affect your health, and on how to reduce the potential hazard associated with mould growth within your home.

Last updated: 20 December 2022

What is mould?

Mould is part of a group of very common organisms called fungi that also include mushrooms and yeast. It is present virtually everywhere, both indoors and outdoors.

Mould may grow indoors in wet or moist areas that lack adequate ventilation, including walls or wallpaper, ceilings, bathroom tiles, carpets (especially those with jute backing), insulation material and wood. If moisture accumulates, mould growth will often occur on indoor surfaces. Many different types of mould exist, and they all have the potential to cause health problems.

What are possible health problems from contact with mould?

In order to reproduce, mould produces tiny particles called spores. Spores are carried in the air and may cause health problems if inhaled by people who are sensitive or allergic to them.

Health effects of mould exposure include a runny or blocked nose, irritation of the eyes and skin, and sometimes wheezing. For people with asthma, inhaling mould spores may cause an asthma attack.

Very rarely, people may develop a severe mould infection, usually in the lungs. One such infection is the rare immune disorder known as hypersensitivity pneumonitis, in which the lungs become inflamed from breathing in large amounts of specific substances (allergens) frequently over a period of time. Symptoms of hypersensitivity pneumonitis are similar to the flu (fever, cough, chills, shortness of breath) and may become more severe the longer the exposure continues.

If someone has hypersensitivity pneumonitis it is important that it is diagnosed by a doctor so that steps may be taken to manage the condition and avoid exposure to allergens that may be responsible.

It is important to note that most people will not experience any health problems from coming into contact with mould. Everyone breaths in mould spores and most people have no symptoms.

If you or your family members suffer health problems after coming into contact with mould, contact your doctor. In the case of a life-threatening emergency, phone 000.

Who is at greatest risk of health problems from contact with mould?

People with asthma, allergies, or other breathing conditions may be more sensitive to mould. People with weakened immune systems (such as people with HIV infection, cancer patients taking chemotherapy or people who have received an organ transplant) and with chronic lung diseases (such as Chronic Obstructive Pulmonary Disease (COPD) and emphysema) are more at risk of mould infection particularly in their lungs.

How can I prevent mould from growing in my home?

Although mould can be found almost anywhere, it needs moisture and nutrients to grow. The following actions can help prevent mould growth by reducing dampness in the home.

Maintain proper ventilation

  • Turn on exhaust fans, particularly when bathing, showering, cooking, doing laundry and drying clothes.
  • Open windows when weather permits, to improve cross ventilation.

Reduce humidity

  • Limit the use of humidifiers.
  • Limit the number of fish tanks and indoor plants.
  • Limit use of unflued gas heaters

Control moisture and dampness

  • Repair all water leaks and plumbing problems, for example, burst water pipes, leaking roof or blocked rain gutter
  • If water enters your home, completely clean and dry water-damaged carpets and building materials. Discard material that cannot be cleaned and dried completely.

Rising and lateral damp

Rising damp is ground moisture rising up a brick or stone wall. Poor sub-floor ventilation or moisture in the sub-floor area will worsen the problem. This can be fixed by installing a new dampcourse or waterproof barrier in the wall. Ensure the weep holes and air vents at the base of your home are uncovered.

If you have rising or lateral damp, an experienced building consultant can check the damp course and recommend ways to fix the problem.

What can I do if I have mould in my home?

It is good to remove mould as soon as it appears. This may take some effort. Remember that mould is likely to return unless you also take steps to treat the cause of the problem (see above).

If you rent your home and have taken measures to ensure the building is properly ventilated and mould is still growing, you should raise the issue with the owner or real estate agent. Tenants seeking further information about their rights and responsibilities may wish to call NSW Fair Trading on 13 32 20. Public housing tenants should call the Housing Contact Centre on 1800 422 322.

How can I remove mould from my home

  • For routine clean-up of mouldy surfaces, use mild detergent or vinegar diluted in water solution (4 parts vinegar to 1 part water).
  • If the mould is not readily removed and the item cannot be discarded, use diluted bleach solution (250mls of bleach in 4 litres of water) to clean the surface. When using bleach, protective equipment is recommended: PVC or nitrate rubber gloves; safety glasses; and safety shoes. Make sure the area is well-ventilated while you are cleaning with bleach.
  • Ensure the surface is dried completely once cleaned.
  • Absorbent materials, such as carpet may need to be professionally cleaned or replaced if they are contaminated with mould.

Should I get tests for mould in my home?

Since most mould is visible, it is generally not necessary to test for mould in the home. However, some mould contamination may be present in cavities or the ceiling.

Symptoms associated with sensitivity or allergy to mould are diverse and non-specific and therefore symptoms alone are not a reliable indicator of mould. Indoor surfaces need to be inspected to determine the extent of mould.

If you think you have mould in your home but cannot find the source of the problem, you could employ an occupational hygienist. For a fee, these professionals can provide specialist mould testing and consultancy services.

Further information

Further advice concerning the health risks of mould can be obtained from your local public health unit. In NSW call 1300 066 055 to talk to your local Public Health Unit.

Current as at: Tuesday 20 December 2022
Contact page owner: Environmental Health