Is Mould Dangerous? Health Risks You Need to Know

Mould in your Perth home is more than an eyesore. It releases spores and chemicals that can cause serious health problems, especially for children, elderly people, and anyone with respiratory conditions. Here is what the science says and when to take action.

How Mould Affects Your Health

Mould affects health through three primary mechanisms: allergen release, irritant release, and in some species, mycotoxin production. The severity of health effects depends on the species of mould, the concentration of spores in the air, the duration of exposure, and the individual's sensitivity and overall health.

Allergic Reactions

The most common health effect of mould exposure. Mould spores act as allergens, triggering immune responses in sensitised individuals. Symptoms include sneezing, runny or blocked nose, itchy and watery eyes, skin rashes, and worsening of existing eczema. An estimated 10-20% of the Australian population is sensitised to mould allergens.

Respiratory Effects

Mould exposure is strongly linked to respiratory problems. It can trigger asthma attacks in people with existing asthma, cause new-onset asthma in previously healthy individuals (particularly children), lead to chronic coughing and wheezing, cause bronchitis and upper respiratory tract infections, and worsen chronic obstructive pulmonary disease (COPD).

Irritant Effects

Even in people who are not allergic to mould, the volatile organic compounds (VOCs) and microbial fragments that mould produces can irritate the eyes, skin, nose, throat, and lungs. This is the musty smell you notice in a mouldy home — those chemicals are actively irritating your mucous membranes.

Toxic Effects (Mycotoxins)

Certain mould species, including Stachybotrys chartarum (black mould) and some Aspergillus species, produce mycotoxins — toxic secondary metabolites that can cause more serious health effects including neurological symptoms, immune suppression, and in severe or prolonged cases, organ damage. Mycotoxin exposure is a particular concern in homes with extensive hidden mould growth.

Infections

In immunocompromised individuals (those undergoing chemotherapy, organ transplant recipients, people with HIV/AIDS, or the very elderly), mould spores can cause invasive fungal infections. Aspergillus is the most common species involved. These infections can be life-threatening and require urgent medical treatment.

Who Is Most at Risk from Mould Exposure?

While mould can affect anyone, certain groups face significantly higher risks:

Infants and young children: Developing immune and respiratory systems, higher breathing rate relative to body size, and more time spent on floors where spores accumulate make children particularly vulnerable. Multiple studies link early mould exposure to childhood asthma.
Elderly people: Declining immune function and often pre-existing respiratory conditions increase susceptibility to mould-related illness.
Asthma sufferers: Mould is a well-documented asthma trigger. The Asthma Foundation estimates that 10% of Australians have asthma, and indoor mould is one of the most common environmental triggers for attacks.
People with allergies: Those with existing hay fever, eczema, or other allergic conditions are more likely to develop mould sensitisation and experience allergic reactions.
Immunocompromised individuals: People with weakened immune systems from medical treatments, chronic illness, or organ transplantation face the risk of invasive fungal infections.
People with chronic lung disease: Those with COPD, bronchiectasis, or cystic fibrosis are at higher risk of mould-related infections and symptom exacerbation.
Pregnant women: Some research suggests mould exposure during pregnancy may be linked to adverse outcomes, though more research is needed. The precautionary approach is to minimise exposure.

When to Seek Medical Advice

See your GP if you experience any of the following, particularly if symptoms improve when you are away from home:

Persistent coughing, wheezing, or shortness of breath
Worsening asthma symptoms or increased use of reliever medication
Chronic sinus congestion or repeated sinus infections
Ongoing skin rashes or irritation
Persistent headaches or fatigue that improve away from home
Recurring respiratory infections in household members

Seek urgent medical attention if you experience:

Severe difficulty breathing or chest tightness
Anaphylactic-type reaction (swelling, hives, difficulty swallowing)
High fever with cough in an immunocompromised person

Your doctor may refer you to a respiratory physician or allergist for specific testing. Let them know about the mould in your home so they can consider it in their assessment.

Mould Health Risks in the Perth Context

Perth's specific conditions create particular health risk scenarios:

Evaporative air conditioning: Perth's widespread use of evaporative coolers means many households are exposed to elevated indoor humidity and mould growth around ceiling ductwork. Mould spores from these systems are distributed throughout the home via the air conditioning itself.
Winter condensation in bedrooms: Perth families often discover mould on bedroom walls and windows during winter. Because people spend 7-9 hours sleeping in these rooms, the total exposure time is significant.
Hidden mould in older homes: Perth's pre-1970s housing stock with limestone foundations and inadequate ventilation often harbours hidden mould behind walls and under floors. Occupants may experience health symptoms without seeing visible mould.
WA Department of Health guidance: The WA Department of Health advises that indoor mould should be removed as quickly as possible and the underlying moisture source addressed. They recommend consulting a health professional if you believe mould exposure is affecting your health.

What to Do If You Have Mould in Your Perth Home

Do not ignore it. Mould does not go away on its own. It will continue to grow as long as moisture is present.
Reduce your exposure. Increase ventilation, avoid sleeping in heavily affected rooms if possible, and keep doors to mouldy rooms closed to limit spore spread.
Do not disturb large areas. Scrubbing or wiping large mould colonies without proper containment releases enormous numbers of spores into the air, temporarily making the problem much worse.
Get a professional assessment. A qualified mould inspector can determine the species, extent, and underlying cause. We connect you with qualified specialists across Perth.
Address the moisture source. Mould remediation without fixing the cause (leak, condensation, ventilation, rising damp) is a waste of money because the mould will return.
See your doctor if you or your family members are experiencing health symptoms.

Mould Health Risk FAQs

Under the Residential Tenancies Act 1987 (WA), landlords must provide and maintain premises in a reasonable state of repair. If mould is caused by a structural issue, plumbing leak, or ventilation deficiency, the landlord is generally responsible for remediation. Tenants are responsible for mould caused by their own lifestyle factors such as not using exhaust fans.

Document the mould with dated photos, report it to your property manager or landlord in writing, keep copies of all correspondence, allow reasonable access for inspection, and do not attempt large-scale removal yourself. Written notification creates a record that may be important if the matter escalates.

If mould makes the property uninhabitable and the landlord fails to remediate after proper notice, you may apply to the Magistrates Court for lease termination. Seek advice from the Department of Mines, Industry Regulation and Safety (DMIRS) or a tenancy advocate before taking this step.

Generally, the landlord pays for mould removal where it results from property defects such as leaks, poor ventilation, or structural issues. Tenants may be liable if the mould is caused by their failure to ventilate, report leaks, or maintain reasonable cleanliness.

No. Withholding rent is not permitted under WA tenancy law, even if the property has mould issues. Instead, you should report the issue in writing, request repairs through proper channels, and if unresolved, apply to the Magistrates Court for a repair order.

If your landlord does not respond within a reasonable time (typically 14 days for non-urgent, 24-48 hours for urgent repairs), you can apply to the Magistrates Court for a repair order. Contact the DMIRS tenancy helpline on 1300 304 054 for guidance on the process.

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