The Science of Stubborn Smells: Professional Odour Removal Techniques Beyond Air Fresheners:
- diego9370
- Jan 13
- 5 min read
Why nasty smells linger and how to banish odours.
Unpleasant washroom smells are one of the fastest ways to trigger complaints in offices, hospitals, shopping centres, transport hubs, gyms, and venues.
That is because most washroom odour is not a cleaning failure. It is an air quality problem.
If you treat smell like a surface problem, you end up masking symptoms. If you treat it like a gas problem, you can actually fix it.
Why do washrooms smell even when they are clean?
Washroom malodour usually comes from gases that hang in the air and cling to porous surfaces. The main culprits are volatile organic compounds (VOCs) and other odour-causing gases released from urine, waste systems, damp materials, and some cleaning products. VOCs are common indoor pollutants and come from many everyday indoor sources, not just “dirty” spaces.
On top of that, typical toilet and urinal malodours include compounds such as ammonia, sulphur compounds, and amines, plus urine odour markers like p-cresol. These are gas-phase molecules. You cannot wipe them off a wall, and you cannot “particle filter” them away.
The real-world problem: it looks clean, but it still smells
This is the scenario most facilities teams recognize:
The washroom looks fine.
The cleaning schedule is being followed.
Complaints still come in, often at the same times each day.
That usually points to a mismatch between demand and response. Footfall spikes, the air loads up with odour-causing gases, and the space does not recover fast enough between peaks.
Why air fresheners and aerosols fail long-term
Aerosols and fragrance dispensers change the smell, but they do not remove the odour molecules. If the underlying gases stay in the air, the complaint returns. Often, the “solution” becomes stronger fragrance, which can create a second problem: people complain about the fragrance itself.
Research on fragranced consumer products, including air fresheners, shows they can emit VOCs, including substances classed as hazardous air pollutants, and they can contribute to secondary pollutants formed indoors.
So you end up in a loop: mask, fade, mask again. It costs money, adds chemicals to the air, and does not solve the root cause of odour.
HEPA vs activated carbon: understand the difference
People push HEPA because it has a strong reputation. Fair. HEPA is excellent for particles.
But odours are usually not a particle problem.
The EPA explains that most filters are designed to filter either particles or gases. If you want gas removal, you need an activated carbon filter or another gas phase filter designed for that job.
Here is the clean distinction:
HEPA filtration helps with particles like dust, pollen, and some aerosols.
Activated carbon helps with many gases, including VOCs and odours, by adsorption.
And one practical detail that matters for buying decisions: there is no widely used gas removal rating system like CADR, and carbon performance depends heavily on how much media you use and when you replace it.
Ventilation helps, but it is not a silver bullet
Ventilation should be part of the answer, but it does not guarantee odour control on its own.
Real buildings have real constraints:
Fans get poorly maintained.
Air paths are imperfect.
Odour sources sit in “dead zones” where air does not move well.
Peak footfall can overwhelm a time-based approach.
That is why the most reliable approach combines ventilation with source control and gas phase filtration.
The role of data in smell complaints and washroom management
Most washroom problems get worse when you lack visibility.
When you cannot see usage patterns, teams fall back on fixed schedules and reactive checks.
That leads to predictable waste:
Over-cleaning quiet areas “just in case”.
Under servicing peak periods.
Chasing complaints instead of preventing them.
Usage and service data changes the game because it helps you align effort to demand. You stop guessing and start managing.
What actually works for odour control in commercial washrooms
If you want fewer smell complaints, focus on prevention, not coverage.
A practical approach looks like this:
Remove odours at source with gas phase filtration Activated carbon targets odour-causing gases and VOCs by adsorption, which is the right mechanism for many washroom smells.
Put odour control where the odour starts
Waste points, urinal areas, bins, and other hotspots matter. If you treat the whole building but ignore the source, complaints continue.
Use fragrance as a finish, not a fix Fragrance works best when the air is already clean. Otherwise, you create “fragranced odour”, which is exactly the complaint you do not want.
Use data to align cleaning to demand You reduce complaints fastest when you service peaks and prevent peaks from turning into incidents.
How Ecobreeze deals with odour
Ecobreeze takes the “gas problem” seriously.
It draws air in, runs it through activated carbon filtration to adsorb odour-causing gases and VOCs, then adds controlled fragrance after filtration.
That order matters because it avoids circulating already contaminated air with added scent.
So the output air is treated first, then fragranced.
Quick answers to common search questions
Why does my washroom still smell after cleaning?
Because cleaning removes visible dirt. Odour complaints usually come from gas phase compounds like VOCs, ammonia, amines, and sulphur compounds that remain in the air and on porous materials.
Do HEPA filters remove odours?
HEPA targets particles. Odours are gases. You typically need activated carbon or another gas-phase filter for odour control.
Are air fresheners bad for indoor air quality?
Many air fresheners emit VOCs and can contribute to indoor chemical mixtures. They also mask odour rather than removing it.
What is the best way to reduce washroom smell complaints?
Use a root cause approach: gas phase filtration near the source, sensible ventilation, and cleaning schedules aligned to real usage.
The takeaway
Washroom smell control is not about “more fragrance”. It is about removing the gases that create complaints, then running the space in a way that prevents peaks from becoming incidents.
If you fix the air, you fix the story users tell about your hygiene. Sources
US EPA, Guide to Air Cleaners in the Home
Used to support the distinction between particle filtration and gas filtration, the role of activated carbon for gases and odours, and the note that gas removal lacks a simple rating system like CADR. https://www.epa.gov/indoor-air-quality-iaq/guide-air-cleaners-home
US EPA, Volatile Organic Compounds Impact Indoor Air Quality
Used to support that VOCs come from many indoor sources and are a common driver of indoor air quality issues. https://www.epa.gov/indoor-air-quality-iaq/volatile-organic-compounds-impact-indoor-air-quality
UK Government, Volatile Organic Compounds (VOCs)
Used to support the plain language definition of VOCs in the UK context. https://www.gov.uk/government/publications/volatile-organic-compounds-vocs/volatile-organic-compounds-vocs
Stenström et al (University of Gothenburg), Activated carbon adsorption of p cresol from urine models
Used to support p-cresol as a urine odour marker and activated carbon’s ability to capture it.
(Linked summary and related materials as indexed in search results) https://www.gu.se/en/news/activated-carbon-can-lock-in-odor-instead-of-it-being-released
Abney et al, Toilet hygiene and related malodour research review
Used to support examples of common toilet and urinal malodour compounds such as ammonia, sulphur compounds, and amines. https://www.sciencedirect.com/science/article/pii/S0048969722020025
Potera (2011), Environmental Health Perspectives, Scented Products Emit a Bouquet of VOCs
Used to support the fact that scented products, including air fresheners, can emit VOCs and include hazardous air pollutants. https://pmc.ncbi.nlm.nih.gov/articles/PMC3222987/
Kim et al (2015), Emission of VOCs and the formation of secondary pollutants from scented products
Used to support VOC emissions and secondary pollutant formation linked to fragranced products in indoor environments. https://www.sciencedirect.com/science/article/pii/S0048969715300227
University of Rochester Medical Center, Air Fresheners report (Roc Home Study)
Used to support health and indoor exposure concerns associated with air fresheners and fragranced products.