Mould turns up in plenty of homes. It tends to show up in bathrooms, on ceilings and behind furniture pushed against cold walls. Most of the time it is a nuisance rather than a danger. Still, it can affect some people’s health, so it is worth understanding.
This article explains what mould is, how it can affect health and how to reduce damp at home. It draws on public health guidance from NSW Health and the Northern Territory Government. The advice is general and applies to most homes, though rules for renters differ between states.
What mould is and where it grows
NSW Health describes mould as a type of fungus, related to mushrooms and yeast. It is present almost everywhere, both indoors and outdoors. Mould spreads by releasing tiny spores into the air. There are many types, and all of them have the potential to cause health problems.
Mould grows where it is wet or damp and poorly ventilated. Common spots include walls, wallpaper, ceilings and bathroom tiles. Carpets can harbour it too, particularly those with jute backing. Insulation and wood are other places where it can take hold.
The Northern Territory Government notes that mould needs organic material and moisture to grow. Organic material is found throughout a home, so moisture is the part you can control. That is why most advice on mould is really advice on damp. Deal with the water and the mould has far less chance to grow.
How mould can affect health
According to NSW Health guidance on mould, spores can cause a runny or blocked nose. They can also cause eye and skin irritation and sometimes wheezing. For people with asthma, breathing in spores may trigger an asthma attack. NSW Health also points out that most people will not have any health problems from mould.
Some people are more sensitive than others. People with asthma, allergies or other breathing conditions may react more strongly. People with weakened immune systems face a greater risk of mould infection, particularly in the lungs. This includes people having chemotherapy and organ transplant recipients, along with people with chronic lung diseases such as COPD.
Very rarely, prolonged exposure can lead to a lung condition called hypersensitivity pneumonitis. NSW Health says its symptoms are similar to flu. It says the condition should be diagnosed by a doctor so it can be managed. If you or your family develop health problems after contact with mould, see your doctor.
Reducing damp in your home
Good airflow is the first line of defence. NSW Health suggests running exhaust fans when you shower, bathe, cook or do the laundry. Use them when drying clothes indoors as well. Open windows when the weather allows so air can move through the house.
Moisture also comes from everyday items. NSW Health suggests limiting humidifiers, fish tanks and indoor plants in rooms prone to damp. It also suggests limiting the use of unflued gas heaters. Each of these adds water to the air inside your home.
Leaks are a major source of damp. Repair water leaks and plumbing problems promptly, including burst pipes, leaking roofs and blocked gutters. If water does get in, clean and dry affected carpets and building materials thoroughly. Anything that cannot be fully dried should be thrown out.
Rising damp
Rising damp is moisture from the ground climbing up a brick or stone wall. Poor ventilation under the floor makes it worse. Repairs can include a new damp course or a waterproof barrier in the wall. NSW Health also advises keeping weep holes and base vents clear, and a building consultant can inspect the damp course and recommend repairs.
Outside the house
The outside of your home plays a part too. Gutters, drainage and garden beds against walls can all affect how much water reaches the building. If you are planning outdoor changes, our ideas for a simple landscaped garden makeover are a good starting point. Keep drainage in mind as you plan new beds or paving.
Design choices can help as well. Our article on landscape design trends in New South Wales gardens shows how outdoor spaces are being laid out. Before copying an idea, think about where water will run after heavy rain. Water pooling near walls or vents is worth avoiding.
Cleaning small areas of mould
For routine cleaning, NSW Health suggests a mild detergent or a vinegar solution of 4 parts vinegar to 1 part water. For stubborn mould on items you cannot throw away, it suggests diluted bleach. Its suggested mix is 250 mL of bleach in 4 litres of water. Dry the surface completely afterwards.
Protect yourself while you work. When using bleach, NSW Health recommends PVC or nitrile rubber gloves, safety glasses and safety shoes. Keep the area well ventilated. The Northern Territory Government guide to mould growth warns never to mix bleach with ammonia.
The Northern Territory guide also notes that ordinary paper dust masks do not usually filter out mould spores. It lists a P1 or P2 respirator as part of protective gear. If you have a heart or lung condition, ask your doctor before using a respirator. The guide says children, pregnant women, people over 65 and people with some health conditions should stay away from the area during cleaning.
When to call in help
Some jobs are too big to handle yourself. The Northern Territory guide suggests a professional cleaning company for large amounts of mould, especially after a flood. Carpet with mould in it may need professional cleaning or replacement. If you cannot find the source of the damp, an occupational hygienist can carry out specialist testing for a fee.
NSW Health says routine testing is usually not needed because most mould can be seen. However, mould can hide in wall cavities or ceilings. Symptoms alone are not a reliable sign that mould is present. If something seems wrong, it is reasonable to look more closely.
Renting and mould
Renters have a role, and so do landlords. NSW Health suggests that if you rent and have ventilated the property properly but mould keeps growing, you should raise it with your landlord or agent. Tenancy laws are set by each state and territory, so rights and responsibilities differ. Your state fair trading or consumer affairs office can explain the rules where you live.
Comfort and wellbeing at home
A dry, well aired home is more comfortable to live in. Looking after yourself is part of the same picture. Skin can also feel dry in a warm climate. Our guide to moisturiser recommendations for Perth weather covers everyday skin care in those conditions. If you are reworking the garden anyway, our article on lighting ideas for landscaping design can help you plan new paths and beds at the same time.
Frequently asked questions
Can mould make you sick?
Mould spores can cause a runny or blocked nose, eye and skin irritation and sometimes wheezing. They may trigger asthma attacks in people with asthma. NSW Health notes that most people will not have any health problems from mould.
Who is most at risk from mould?
People with asthma, allergies or other breathing conditions may be more sensitive. People with weakened immune systems or chronic lung disease face a greater risk of infection. If you are in one of these groups, speak with your doctor about mould at home.
What is the best way to stop mould coming back?
Reduce moisture. Use exhaust fans, open windows when you can and fix leaks quickly. Dry anything that gets wet as soon as possible.
Do I need to test my home for mould?
NSW Health says routine testing is usually unnecessary because most mould is visible. Mould can hide in cavities or ceilings, though. An occupational hygienist can test if you cannot find the source.
This article is general information and is not medical advice. If you have symptoms you think may be linked to mould, speak with your doctor or a qualified health professional. In an emergency, call triple zero.