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

Not all mould species are equally harmful, but all indoor mould growth should be taken seriously. Common species like Cladosporium and Penicillium cause allergic reactions in sensitive individuals. More concerning species like Stachybotrys (black mould) and some Aspergillus species can produce mycotoxins that pose risks even to healthy people. The safest approach is to treat any indoor mould as a potential health hazard and have it professionally assessed.

Common symptoms include persistent sneezing, runny or blocked nose, itchy or watery eyes, coughing, wheezing, skin rashes or irritation, headaches, and fatigue. More severe reactions can include asthma attacks, difficulty breathing, sinus infections, and in rare cases with toxic mould exposure, neurological symptoms. Symptoms often improve when you leave the affected environment and worsen when you return.

Health effects can begin within hours of exposure for people who are sensitised or allergic. For others, symptoms may develop over days or weeks of continuous exposure. Some health impacts, particularly chronic respiratory conditions, may develop gradually over months of living in a mouldy environment. The timeline varies significantly depending on the mould species, concentration, and the individual's health and sensitivity.

Yes, you should consult your GP if you are experiencing persistent respiratory symptoms, worsening asthma, or allergy-like symptoms that improve when you are away from home. You should seek urgent medical attention if you experience difficulty breathing, chest tightness, or severe allergic reactions. Your doctor can refer you to a respiratory specialist or allergist if needed.

Prolonged exposure to indoor mould can lead to chronic respiratory conditions, persistent sinusitis, ongoing allergic sensitisation (where you become reactive to mould even in low concentrations), and in immunocompromised individuals, serious fungal infections. Children exposed to mould in their early years may be at higher risk of developing asthma. Removing the mould and addressing the moisture source is essential for long-term health.

Yes, children are particularly vulnerable to mould exposure because their immune and respiratory systems are still developing, they breathe more air relative to their body weight than adults, and they spend more time on or near the floor where mould spores settle. Research has linked early childhood mould exposure to increased rates of asthma, allergic rhinitis, and respiratory infections.

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