Hand Dryers: The Hygiene Problem Behind the Airflow

Many people choose an electric hand dryer for convenience or environmental reasons. No paper, no waste and a quick blast of warm air: it sounds modern and clean. Yet a viral experiment by a scientist suggests that the pleasant airflow conceals a hygiene issue far more unpleasant than most people realise.

The TikTok experiment that unsettled millions

The scientist, known online as “Devon Science”, wanted a precise answer: how many germs end up on skin when hands are held beneath a public hand dryer? Her approach was straightforward, almost classroom-like, but the results resemble a microbiologist’s horror film.

She used two Petri dishes containing growth medium. One was placed directly below a running hand dryer in a public toilet, while the other was left in clean laboratory air as a control. Both dishes were incubated overnight.

The following day, the laboratory comparison was stark. The control dish remained virtually empty. By contrast, the dish from the toilet had developed a thick covering of yellow, black and white spots. Each colony represented a bacterial or fungal group propelled on to the dish by the airflow.

The hand dryer did not act like a hygienic appliance – but like a germ launcher aimed directly at hands and faces.

Which germs hand dryer air contains

Analysis of the colonies revealed a combination that nobody would want to find in a hygiene device. It included typical problematic germs associated with public toilets.

• Staphylococcus aureus: bacteria that can cause abscesses and wound infections and, in rare cases, pneumonia.
• Escherichia coli (E. coli): a common intestinal bacterium linked to faeces, which can lead to diarrhoea, urinary tract infections or more serious illness if transmitted incorrectly.
• Fungal spores: black spots indicated mould or yeast fungi, which can irritate the airways and worsen allergies, particularly in people with asthma or weakened immune systems.

The experiment indicates that a hand dryer does more than dry hands. At the same time, it spreads a mixture of bacterial and fungal particles that had previously been on walls, floors or within the appliance itself somewhere in the toilet.

How hand dryers spread germs at high speed

The central reason lies in their design. Hand dryers draw in room air, accelerate it using a powerful fan and direct it in a concentrated stream towards hands and forearms. There is nothing inherently hygienic about that air.

• Extreme air speed: modern jet hand dryers can reach several hundred kilometres per hour. This allows them to carry tiny water droplets, skin flakes and toilet aerosols from the surrounding air, including the germs attached to them.
• Internal dirt reservoir: in a further test, the scientist swabbed the inside of the dryer with a cotton bud. The bud turned dark, suggesting accumulated dirt and bacterial deposits. When the appliance is switched on again, some of these deposits may be blown back into the air.

This creates a cycle: using the toilet releases germs into the room air, the dryer draws them in and deposits them internally, then sends them out again when it next starts – at face height for users.

Why washed hands become “contaminated” again

After washing, skin may be clean but it is still damp. That moisture makes it more receptive to germs in the air, as microorganisms adhere more readily to wet skin than dry skin.

Anyone who keeps their hands in the airflow for 20 to 30 seconds gives germs time to settle into every crease of the skin. As a result, part of the benefit of careful handwashing is lost again.

What studies say about paper versus air

Separate from social-media experiments, specialist studies have examined for years whether paper towels are more hygienic than warm-air or jet dryers. Many investigations reach a similar conclusion.

For this reason, many hygiene experts favour paper towels in hospitals and care homes, particularly in sensitive areas.

HEPA filters and UV light – a solution or window dressing?

Manufacturers have responded in recent years with technical upgrades. Two terms appear repeatedly: HEPA filters and UV sterilisation.

• HEPA filters: these are intended to filter up to 99.97% of all particles above a certain size from the air. In theory, this reduces the germ load reaching users’ hands. In practice, much depends on maintenance and filter replacement, as dirty filters become less effective.
• UV light inside the appliance: ultraviolet radiation can kill bacteria and fungi. For this to work, however, air must be exposed for long enough and with sufficient intensity. Whether that happens consistently inside compact dryer housings is questionable, depending on the model.

There is also the fact that many older buildings still have conventional models with no additional filtration whatsoever. In a railway station, motorway service area or pub toilet, users are generally more likely to encounter an ageing standard unit than a high-tech version.

What you can do in a public toilet

Despite the risks, nobody can avoid public toilets entirely. A few simple habits can nevertheless reduce personal risk.

Practical tips for travellers, commuters and parents

• If possible, choose paper over air – Where both paper towels and a dryer are available, use paper. Germs go into the bin rather than the air.
• A fallback option: shake your hands – If there is only a dryer, shake excess water into the basin and roughly dry the rest on your trousers or with a tissue.
• Use sanitising gel – Keeping a small bottle in a backpack or handbag can help reduce the number of germs after using the toilet, especially when travelling.
• Keep your face away – If using a dryer cannot be avoided, stand with your head and body slightly to one side so less air blows directly into your face.
• Touch door handles deliberately – Many germs ultimately end up on handles. A paper towel between your hand and the handle, or a brief elbow push, can help here.

Where the problem is especially critical

In many cases, contact with common toilet germs is unlikely to harm a healthy adult. The issue becomes more serious when people who are already vulnerable are involved.

Examples of higher-risk groups include:

• Patients with open wounds or recent operations
• People with severely weakened immune systems
• Premature babies and very young children
• Residents of care homes and homes for older people

In such settings, even a smaller number of problematic germs can have consequences. It is therefore unsurprising that the debate over hand dryers is gathering pace again in many hospitals.

Why we often underestimate germs in everyday life

People do not perceive germs: they rarely smell, they are invisible and they do not hurt at first. We rely heavily on appearance. A shiny white toilet looks clean even when the air is full of microorganisms. An old, slightly crumpled paper towel may appear “grubby”, yet it is often the more hygienic option.

There is also a psychological effect: technology creates a sense of security. An electric appliance with a sensor, LED lighting and a powerful fan seems more modern than a simple paper-towel dispenser. Many people automatically interpret this as “more advanced” and therefore “cleaner”.

This is precisely the point highlighted by Devon Science’s experiment. It makes the invisible visible and demonstrates that high-tech does not automatically mean more hygienic. For operators of restaurants, motorway service areas or offices, this raises an uncomfortable question: are they ultimately cutting costs in the wrong place when they remove paper towels?

For daily life, one simple rule is useful: wash properly first, then dry properly. Anyone who does not rely blindly on the hot airflow reduces their personal risk and also helps protect others with less resistance.