Workplace Odours
Airflow & IAQ · Airflow & IAQ overview
Workplace odours are among the most reported and least well investigated indoor air complaints. They are subjective, intermittent and often migrate from a source that has nothing to do with the area where they are noticed. A structured odour investigation uses ventilation, pressure and pathway analysis to identify the source and the route, and to separate nuisance smells from exposure risk.
Why workplace odours are difficult to diagnose
Odour perception is highly variable. Different people have different sensitivities, olfactory fatigue masks continuous exposure, and many workplace odours are present at concentrations far below those that any standard instrument will register. By the time a complaint is investigated, the smell may have moved or disappeared.
Odours also rarely come from the obvious place. A smell reported in an office may originate from a process two floors down, transported through a service riser. A canteen odour may come from a drain. A 'chemical' smell may be a cleaning product, a degraded floor finish or a vehicle exhaust drawn in through a fresh-air intake. Reliable diagnosis is methodical, not intuitive.
Common odour sources
Most workplace odours originate from a small set of recurring source categories. A structured investigation works through these systematically before reaching for less common explanations.
- Drainage — disused traps, gully seals lost to evaporation, broken vent stacks releasing sewer gas.
- Process activities — solvents, coatings, hot-work, food preparation, chemical handling.
- Stored materials — fuels, cleaning agents, paints and solvents in stores and plant rooms.
- Microbial growth — mould in damp fabric, biofilm in cooling systems, contamination in drain traps.
- External sources — traffic, neighbouring industry, refuse handling — drawn in through intakes or open doors.
- Building services — air handling units with wet filters, heat recovery wheels carrying odour between supply and extract, ageing duct insulation.
How odours move
Once airborne, odours follow the same physics as any other air contaminant. They move with the prevailing airflow, follow pressure gradients from higher- to lower-pressure zones, exploit transfer paths through doors and service penetrations, and can be carried significant distances by recirculating air handling systems.
This is why ventilation, pressure and pathway analysis sits at the heart of odour investigation. Without that analysis, an investigation is reduced to sniffing rounds and guesswork.
How odour investigations are structured
A useful investigation has a clear sequence. It captures the complaint accurately — what is smelled, where, when, by whom, and under what conditions. It maps the building's ventilation, pressure relationships and known sources. It tests airflow directions at boundaries between zones, particularly between the complaint area and any plausible source area. Where appropriate, it samples specific substances suggested by the source category — for example hydrogen sulphide for drainage, VOCs for process or material sources.
Findings are reported with a recommended remediation pathway: sealing transfer routes, restoring extraction performance, fixing drainage, relocating intakes, adjusting pressure relationships or removing the source. Where the source cannot be eliminated, the report describes the residual control that has been put in place and the conditions under which the odour might recur.
Odour nuisance versus exposure risk
Most workplace odours are a nuisance rather than a hazard, but some are markers of hazardous exposure. Hydrogen sulphide, solvent vapour, combustion products and certain process emissions can be smelled at concentrations that already merit control even though they are below the limit of acute effect.
A competent investigation therefore separates the two questions: is this a nuisance odour affecting comfort and complaint rates, or is it a signal of an exposure that needs immediate control? Those are different conversations with different remediation paths, and conflating them is one of the most common failure modes in workplace odour work.
Frequently asked questions
Can odours be measured?
Specific odorous substances such as hydrogen sulphide or named VOCs can be measured directly. Generic 'smell' is harder — olfactometry methods exist but are more often used in environmental than workplace contexts. Most workplace investigations rely on substance-specific sampling combined with structured observational and ventilation analysis.
Why does the smell move around the building?
Pressure relationships change with weather, door use, plant operation and occupancy. An odour pathway that is closed in one set of conditions can open up in another, so the same source can present in different parts of the building at different times.
Is an odour complaint always an air quality issue?
Not always. Some odours indicate genuine pollutant exposure, others are nuisance issues with no health implication, and some are perceptual responses to other discomfort factors such as temperature or stuffiness. The investigation has to distinguish these before recommending action.
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