Mould Health Effects — What Australians Need to Know

Australia's warm and humid climate in many regions supports a range of indoor mould species. The species present in a property indicates the type and duration of moisture conditions that allowed mould to establish.

• Cladosporium — the most commonly identified indoor mould in Australia. Appears as dark green, brown, or black patches. Found on surfaces with moderate moisture exposure including bathroom grout, window frames, and fabrics. Indicates recurring condensation or humidity rather than acute water damage.
• Aspergillus — a large genus with many species; common in homes and workplaces. Some Aspergillus species are opportunistic pathogens for immunocompromised individuals. Aspergillus fumigatus is one species of particular concern in clinical settings. Found in high-humidity areas and on water-damaged building materials.
• Penicillium — blue-green mould commonly found on water-damaged building materials, carpets, and soft furnishings. Indicates sustained moisture exposure. Some species produce mycotoxins under certain conditions.
• Stachybotrys chartarum (black mould) — less common than other species because it requires sustained, heavy saturation of cellulose-based materials (paper, drywall, timber) to establish and grow. Its presence indicates prolonged serious water damage that was not remediated. Produces mycotoxins under certain conditions.
• Alternaria — a common outdoor mould that colonises indoor surfaces after water damage, particularly on shower surrounds, window frames, and fabric. Often an indicator of post-flood contamination where outdoor mould spore load was introduced with floodwater.

Professional mould assessment identifies species present, which informs the remediation approach. AIEH recommends treating all visible mould regardless of species rather than making health risk determinations based on visual species identification alone.

The health effects of mould exposure vary by individual sensitivity, the species present, and the duration and intensity of exposure. Any health concerns should be assessed by a medical professional.

• Low-level exposure — minor respiratory irritation (coughing, sneezing), eye irritation, and skin sensitivity in susceptible individuals. Symptoms often resolve when the individual leaves the affected space. Most commonly associated with surface mould in bathrooms or on window frames with intermittent condensation.
• Moderate exposure — allergic sensitisation can develop with repeated exposure to moderate mould levels. Once sensitised, an individual may react to much lower spore counts. Associated with persistent mould in living areas, bedrooms, or poorly ventilated spaces with ongoing moisture problems.
• Prolonged high-level exposure — asthma exacerbation, chronic respiratory symptoms, fatigue, and — in severe cases — hypersensitivity pneumonitis. AIEH guidance recommends relocation from heavily mould-affected properties for individuals experiencing symptoms. Consult a medical professional about any ongoing health concerns.
• Immunocompromised individuals — people with weakened immune systems (including those undergoing chemotherapy, transplant recipients, and individuals with HIV/AIDS) face higher risk at lower mould levels. Aspergillus fumigatus can cause invasive aspergillosis in immunocompromised individuals exposed to elevated spore counts. Medical guidance should be sought before re-occupying a mould-affected property.

This information is general in nature. Consult a medical professional for advice about your specific health situation.

All Australian states and territories impose habitability obligations on landlords through their Residential Tenancies Act. Mould that makes a property unsafe or unfit for habitation is a maintenance obligation the landlord must address.

State-by-state obligations (general guidance only — seek independent legal advice):

• New South Wales — RTRA s52 requires landlords to provide and maintain the property in a reasonable state of repair. The 2020 reforms introduced minimum habitability standards. Urgent repairs (including serious mould) must be attended to within 24 hours.
• Victoria — RTRA s65B introduced minimum rental standards in 2021, including requirements for adequate ventilation and absence of damp or mould. Landlords must respond to urgent repairs within 24 hours and non-urgent repairs within 14 days.
• Queensland — RTRA s185 requires the property to be fit for habitation and in good repair. The 2023 amendments strengthened minimum housing standards. Urgent repairs must be completed within a reasonable time.
• Western Australia — RTRA s42A requires the landlord to ensure the property is in a reasonable state of repair and fit for habitation. Urgent repairs (those affecting habitability) must be attended to promptly.

If a landlord fails to remediate mould after being notified in writing, tenants may be able to arrange emergency repairs and claim the cost from the landlord, seek a rent reduction, or apply to VCAT (VIC), QCAT (QLD), NCAT (NSW), or the relevant state tribunal for orders requiring repairs.

This section provides general information about legal frameworks only. It is not legal advice. Seek independent legal advice from a tenancy advocate or solicitor for advice about your specific situation.

Not all mould requires a professional remediation contractor. Small areas of surface mould on non-porous surfaces in well-ventilated areas can sometimes be cleaned by occupants with appropriate PPE. The following situations warrant a professional assessment:

• Visible mould exceeds 0.1m² — at this scale, disturbing mould without containment risks spreading spores throughout the property. Professional containment and HEPA air filtration is required.
• Musty odour without visible mould — musty odour indicates active mould growth that is not yet visible — typically inside wall cavities, under flooring, or in ceiling spaces. Thermal imaging and air quality testing can locate the source.
• Symptoms resolve when leaving the property — if respiratory symptoms, headaches, or fatigue improve when you are away from the property and return when you come back, mould or other indoor air quality issues may be the cause. Professional air quality testing can identify elevated spore counts.
• HVAC smell — a musty or earthy smell when the HVAC system runs indicates mould contamination in the ductwork or on coils. Running a contaminated system distributes spores throughout every room served by the system.
• Post-flood or post-leak assessment — any property that has experienced flooding or a significant water leak should be assessed for mould within 72 hours if structural drying has not been completed. Mould can establish on wet building materials within 24–72 hours under warm, humid conditions.