Odours are one of the most immediate and powerful triggers of concern in indoor environments. Occupants are often highly sensitive to smells, and the presence of an unusual or persistent odour can quickly raise questions about building safety and indoor air quality. In many cases, odours prompt concern even before health symptoms are reported, making them one of the most common reasons occupants question whether something is wrong within a space.

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A key point to understand is that odours do not occur without cause. They do not appear randomly or “out of thin air.” Every odour is associated with a source and a pathway, whether that source originates indoors or outdoors.

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Because odours are closely tied to sources and pathways, they can provide useful insight into how a building interacts with its surroundings and how indoor spaces are being used. For example, a chemical-type odour may suggest off-gassing from materials or products, while sewage-like odours may indicate drainage or plumbing-related concerns. Musty odours are commonly associated with prolonged moisture conditions and may warrant further attention in the context of indoor air quality.

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Beyond nuisance, odours can affect occupant comfort and wellbeing. Certain odour sources may irritate the eyes, nose, or throat, trigger headaches, or exacerbate respiratory conditions in sensitive individuals. Even when measurable health effects are not evident, persistent or unpleasant odours can increase stress, reduce concentration, and negatively influence how occupants perceive the indoor environment.

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Air Quality Measurement Systems Limited (AQMSL) conducts professional odour investigations for commercial, industrial, and institutional buildings where persistent or unexplained indoor odours have been identified. Recognising odours as indicators of sources, occupant activities, and air movement pathways allows organisations to respond more effectively and appropriately to occupant concerns.