Introduction to IAQ and Mould

Mould is not just a cosmetic problem, and the sooner you get that across to everyone on site, the better your job will go. When mould grows inside a building, it releases spores and mycotoxins into the air. Those particles get into the ventilation system, settle on surfaces, and get breathed in by the people living or working there. Respiratory illness, allergic reactions, and serious infections in vulnerable people are all real outcomes, not just liability language on a work order. The high-risk genera you will encounter most often in water-damaged Australian buildings are Stachybotrys, Aspergillus, and Chaetomium. These are not rare finds. If a property has had a slow leak behind a wall or a roof that has been weeping for months, there is a reasonable chance at least one of them is present. Safe Work Australia sets workplace exposure standards that include general dust and particle limits, and those standards apply to you and your crew working in a mould-affected environment, not just to the occupants.

The indicators that mould is affecting indoor air quality are usually right in front of you if you know what to look for. Elevated spore levels compared to outdoor baseline air is the technical marker, and that is what your air sampling will confirm or rule out. But before you even pull out a spore trap, your nose and your eyes are doing their own assessment. That musty, earthy smell that hits you when you open a wardrobe or pull back a skirting board is caused by microbial volatile organic compounds, MVOCs, which are off-gassing from active mould colonies. Visible staining or discolouration on walls, ceilings, and soft furnishings is the other obvious tell. Dark patches, green or black streaking, or that characteristic fuzzy growth on gyprock or timber framing all point to the same problem: moisture has been sitting long enough for mould to establish itself.

Picture this: you arrive at a residential property after a referral from an insurer. The homeowner meets you at the door and says, "Look, I just wiped it off with bleach a couple of times but it keeps coming back." That is one of the most common things you will hear, and it is your cue to explain, calmly and clearly, that surface cleaning does not remove mould. It addresses what is visible on the surface but leaves the root cause untouched and the spore load in the air unchanged. What you actually need to do is find and fix the moisture source first, whether that is a leaking pipe, rising damp, or condensation from inadequate ventilation. Then you remove the contaminated materials that cannot be properly cleaned, and finally you verify through air quality testing that spore levels have returned to a safe baseline before you hand the job back. Skipping any one of those three steps means the mould comes back, the client calls again, and the insurer starts asking questions about the quality of your work.

The practical takeaway for your next job is this: treat every mould call Your scope of work needs to address the moisture, the contaminated material, and the verification. When you are on site, document the indicators you find, the smell, the visible growth, the location relative to any water source, because that documentation supports your scope and protects you if the insurer or a building assessor pushes back. If anyone on site is in a high-risk health category, elderly, immunocompromised, or very young, flag that early and factor it into your containment and communication plan. The air inside that building is what people are breathing every day, and your job is to make it safe again.