Damp is not a rare household fault in this city — it is close to a seasonal default, and by August a very large number of Melbourne homes are running warm, sealed and humid. That is what makes mould and your health such an awkward pair to untangle: the symptoms are near-identical to the ones an ordinary cold, damp winter produces anyway.
Blocked sinuses, a sore throat, tiredness, a chest that never quite clears. Read on and you should be able to tell, with reasonable confidence, whether the house you live in is contributing to how your household has been feeling — and what to do with that answer.
The Pattern That Gives It Away
Mould exposure symptoms are unremarkable alone: blocked sinuses, an irritated throat, itchy eyes, a cough that never quite finishes, headaches, unusual tiredness. Each has a dozen ordinary explanations.
What matters is where they happen. Symptoms that ease within hours of leaving home and return that evening point at the building. So does one bedroom’s occupant being consistently worse than everyone else, or a winter “cold” now in its sixth week. If you can predict how you feel from which room you are in, that is a building pattern, not a viral one.
What You’re Breathing: How Mould and Your Health Are Linked
A visible patch is the colony, not the exposure. The exposure is airborne, and it comes in three forms.
Spores are the reproductive cells mould releases to colonise new surfaces — microscopic, light enough to stay airborne for hours, small enough to reach deep into the airways. Hyphal fragments are broken pieces of the mould’s root structure, shed when a colony is disturbed by air movement or scrubbing. Microbial Volatile Organic Compounds (MVOCs) are the gases actively growing fungi give off — the musty smell itself, and the reason a hidden colony is often detectable before it is visible.
The Better Health Channel links prolonged indoor mould exposure with nasal congestion, sneezing, coughing, wheezing, and the worsening of asthma and allergic conditions. The pattern is irritation and aggravation: mould makes existing respiratory conditions harder to control, and irritates airways that were previously untroubled.
Who Is Most at Risk
Two households in identical houses can experience the same colony very differently. Affected first and worst are infants and young children, whose lungs are still developing; older adults; anyone managing asthma, hay fever or chronic sinus problems; and anyone immunocompromised or taking immune-suppressing medication. The National Asthma Council Australia identifies damp and mouldy indoor environments as a recognised trigger for asthma and allergies.
Occupancy matters as much as biology. Whoever sleeps in the coldest bedroom breathes far more of that air than someone out of the house all day.
Why a Melbourne Winter Concentrates Exposure
Melbourne’s damp season does not create mould by making the outdoors wetter. It creates mould by changing how we run our houses.
From May, windows stay shut and heaters run. Every shower, indoor clothes drying and sleeping person adds moisture to air with nowhere to go. That air meets cold external walls and single-glazed windows and condenses into water on surfaces that stay damp for weeks. Meanwhile the air exchange that would dilute spores and MVOCs has stopped, so concentrations in the rooms you sleep in climb through the season.
Newer and retrofitted homes can be worse rather than better, because draught-sealing reduces uncontrolled air leakage without replacing it with controlled ventilation — the trap covered in our guide to sealed house syndrome. The result is a warm, sealed, humid box: good for energy bills, good for fungal growth.
What Mould Exposure Is Not
Being straight about the limits matters here, because fear helps nobody make a good decision.
“Toxic black mould” is this industry’s most oversold idea. Some moulds do produce mycotoxins — chemical compounds that can be harmful — but the claims made about them online run well ahead of the evidence, and colour alone tells you nothing reliable about species or hazard. A dark patch is a reason to find the moisture source, not to panic.
Nor is mould the explanation for every symptom. Its overlap with ordinary respiratory illness, hay fever, dust-mite allergy and asthma is large, and separating them is medical work. If someone at home is unwell, a GP should assess them; our part of the problem is the building. Our post on winter asthma versus home allergy covers how that distinction plays out over a Melbourne winter.
Why Cleaning the Surface Doesn’t Remove the Exposure
Wiping a patch off the wall changes what you can see, not what you breathe.
On non-porous surfaces — tile, glass, sealed metal — mould sits on top and can be removed. On porous materials like plasterboard, timber, grout and carpet, it sends hyphae, microscopic root-like threads, into the material to anchor and feed. Cleaning removes the visible growth and leaves that root system, so the patch returns within weeks. Scrubbing a disturbed colony also launches spores into the room, raising exposure at the moment you are trying to reduce it. Bleach cannot penetrate porous material, so it strips the colour and leaves the biology intact.
That gap is the difference between cleaning and remediation. Remediation under the ANSI/IICRC S520 standard means containing the work area, physically removing contaminated material, drying the structure, and correcting the moisture source — which is why the certification of whoever attends matters, as our guide to using an IICRC-certified expert sets out.
What an Inspection Establishes
A health-driven inspection is a moisture investigation, not a visual once-over. Thermal imaging locates the cold, damp zones where condensation forms behind linings, moisture meters quantify how wet the materials actually are, and sampling, where warranted, establishes what is airborne relative to outdoors. The output is a diagnosis: where the water comes from, how far contamination extends past what is visible, and what has to change for it not to return.
Conclusion
If your family’s symptoms follow the house rather than the season, the useful question is not which spray to buy — it is where the moisture is coming from. Mould is a symptom of a building failure, and the exposure continues for as long as that failure goes uncorrected. Establishing the source is the first real step, and booking a mould inspection is a sensible way to begin.
Frequently Asked Questions (FAQs)
Can mould in the house make you sick?
Yes — indoor mould exposure is linked to respiratory irritation, nasal congestion, coughing, wheezing and the worsening of asthma and allergic conditions. Children, older adults and anyone with an existing respiratory condition tend to be affected first. Persistent symptoms should be assessed by a GP alongside investigating the building.
Is black mould more dangerous than other mould?
Colour is not a reliable guide to risk. Some moulds produce mycotoxins, but claims about “toxic black mould” are routinely overstated, and identifying a species requires laboratory analysis rather than a visual judgement. Any mould growing indoors signals a moisture problem worth investigating, whatever its colour.
Do I need to move out of my house if I find mould?
Most households do not need to leave over a small, contained patch of surface mould. Relocation is worth discussing with your GP if a resident is immunocompromised or has severe asthma, or if contamination is extensive across several rooms.
Will an air purifier fix a mould problem?
An air purifier can reduce airborne spore levels while it runs, but it does not address the moisture source or the colony producing them. Filtration treats a symptom while growth continues until the water problem is corrected.