Introduction to Odour Control and Removal Techniques

Every odour job starts with the same question: what is actually producing the smell, and where is it coming from? That sounds obvious, but you would be surprised how often a tech walks in, sprays a deodoriser around, and calls it done. That is not odour control, that is odour hiding, and it will not hold up to a re-inspection or an insurer's scope review. Odour is caused by volatile organic compounds, VOCs, that off-gas from a source material and bind to the olfactory receptors in the nose. The type of compound, its concentration in the air, and the substrate it is sitting in or on will determine which elimination method actually works. A microbial odour from mould growth, which produces MVOCs, needs a completely different approach to a protein decomposition odour from sewage, or a combustion odour from smoke and carbon residues. Chemical odours from solvents or adhesives are different again. Getting the category right before you touch anything is not a formality, it is the foundation of every decision you make on that job.

Picture this: you arrive at a house where the owner has already tried three different supermarket sprays over the past week. She meets you at the door and says, "I don't know why it still smells, I've been spraying it every day." That is your first clue that the source has not been dealt with. Walk in, do your odour assessment immediately, and do it fast, because you have roughly fifteen to twenty minutes before olfactory fatigue sets in and you stop noticing what the nose picked up on entry. That initial walk-through is your best diagnostic window. Move room by room, rate the intensity on a zero to ten scale as you go, and mark it on a floor plan. Do not guess, do not rely on memory, write it down. Where the number is highest, that is where you focus your source investigation. In this scenario, a quick check of the subfloor access might reveal the actual source, a sewage leak or a dead animal, that the sprays were never going to touch.

Alongside the olfactory scale, use a PID meter to screen for elevated VOC concentrations in parts per million. The human nose is a useful instrument but it is not objective, and olfactory fatigue makes it unreliable for anything beyond that first assessment. A PID gives you a number you can write in your report and compare at re-inspection. Think of the two tools as working together: the olfactory scale tells you where the odour feels strongest to a fresh nose, and the PID tells you where the chemistry is actually elevated. If those two readings point to the same zone, you have found your source area. If they diverge, dig further, because sometimes a masking product has suppressed the perceived intensity in one area while the VOC concentration is still high. An assessor reviewing your documentation wants to see both data points, not just a technician's opinion.

Understanding the source-receptor pathway is what separates a systematic approach from guesswork. Odour travels from its source through a medium, whether that is air movement, a porous material like carpet or plasterboard, or an HVAC system circulating contaminated air, and it reaches the receptor, which is the person experiencing it. Disrupt any part of that pathway and you reduce the impact. Seal the source, block the medium, or protect the receptor. In practice, this usually means confirming and removing or treating the source first, then addressing residual contamination in the medium, and finally verifying clearance with a fresh-nose evaluation from someone who has not been on site. Never sign off on a deodorisation job using the same nose that has been in the building for three hours. Bring in a colleague, or step outside for a genuine break before your final walk-through. Masking without source removal is not a compliant outcome, and any assessor or insurer worth their fee will pick it up on re-inspection.