While the benefits of washing your hands have been understood for more than a century, the benefits of hand drying are yet to become public knowledge. Equally, the best method of hand drying has historically divided opinion.
Even today, public restrooms frequently offer both paper towels and electric hand dryers as methods of hand drying.
On the topics of hand drying and the best method of hand drying, what does the research say?
If you were to watch people drying their hands after using a public bathroom, you’d probably decide hand drying wasn’t actually that important. It’s common for people to skip hand drying altogether after they’ve washed their hands. Those that do dry their hands aren’t always that enthusiastic about it.
Some simply flick a few droplets of water into the sink and others wipe their hands on their clothing without breaking their stride. Those that do use electric hand dryers usually do so only impatiently, typically abandoning the process without fully drying their hands.
Hand washing greatly reduces the number of bacteria living on your hands, but it doesn’t eliminate the bacteria altogether. Some residual strains survive the wash which probably explains why the most contaminated item in most bathrooms is actually the bathroom sink.
Wet hands transfer bacteria to other surfaces. A study published in the British Journal of Anaesthesia as far back as 2001 found bacterial transfer to be “greatly increased with wet hands”. A second study, published by Cambridge University Press in 1997, found hand drying reduced the numbers of bacteria transferred to samples of skin, utilities and, yes, food, by an order of 99%.
Think about all those people skipping hand drying then opening the public bathroom door, transferring residual bacteria onto the door handle one after another, creating a melting pot of resilient bacteria all swimming around happily in a layer of moisture. The only way out of the bathroom is by opening that door.
You then start to see what makes hand drying so important.
“There are several reasons to dry your hands, the first and most obvious being that walking around with wet hands is awkward and impractical. It is also socially unacceptable to greet others (be it hugs or shaking hands) with wet hands. From a hygiene perspective, wet hands make it much easier for germ transferal from a person to a surface; imagine the mess of the toilet door handle if nobody dried their hands.” Steve Levy, MD, Handy Dryers
There are three main differences. The first is the most obvious.
At home, the germs are your own germs. Public bathrooms harbour everyone’s different germs. That’s compounded by the fact so many more people use public toilets than do private toilets.
The third difference is the overflowing bin full of used paper towels that’s a customary feature in public toilets that don’t offer electric hand dryers. As we know, bacteria exist in the residual water on our hands after we wash them. Hand drying with paper towels transfers the bacteria to the paper towels.
Storing contaminated paper towels in one space is therefore far from ideal when it comes to infection control. In short, you’re less likely to encounter dangerous germs and bacteria in private toilets than public toilets – and that has a lot to do with the fact so many people still fail to take hand drying seriously.
This is perhaps the biggest question of them all. Are you better off drying your hands with paper towels or with electric hand dryers?
On this one, research is actually quite divided… but probably not for the reasons you might think.
Much of the research published on the topic of hand drying with paper towels and hand drying with electric hand dryers has been funded either by Dyson (makers of electric hand dryers) or Kimberly-Clark (who are in the paper towels business). Unsurprisingly, the conclusions often side with those funding the research. So let’s try to disentangle at the facts.
This Biocote study is a good place to start. To demonstrate their antimicrobial technology, Biocote swabbed 15 surfaces in a public restroom; everything from ceiling air vents to the area under the toilet. They found 14 of the 15 surfaces to be contaminated with bacteria colonies, and the only surface not to be contaminated to be the soap dispenser – which had been treated with Biocote products.
The study didn’t swab a paper towel dispenser but given the pervasiveness of germs, and given paper towels are the first thing people touch with wet, contaminated hands, it’s probably safe to assume the paper towel dispenser harbours bacteria.
The fact that electric hand dryers are used for hand drying means they’re probably contaminated, too, but, of course, you don’t actually have to touch electric hand dryers with automatic sensors.
The environmental effects of both options also need to be considered, and this is probably where hand drying using paper towels really falls behind electric hand dryers. 2011 MIT research compared the seven most common hand drying methods in public toilets before concluding hand drying with paper towels fuelled as much as 70% more carbon emissions than the newest electric hand dryers on the market. That’s a lot less trees used to produce paper towels, a lot less contribution to climate change, and a lot less money wasted. Estimates have found 29 hands are dried at the cost of one paper towel with high speed electric hand dryers.
The final consideration in the hand drying debate is around additional functionality. For the most part, paper towels are paper towels. Electric hand dryers, however, have evolved over time.
First, we had electric hand dryers that dried hands through evaporation and took around 45 seconds to work. If we’re focusing on the facts, while these early electric hand dryers were a minor improvement on paper towels, the difference wasn’t astounding. Then came high speed hand dryers that blast water away from hands in as little as 8 seconds. These are the green electric hand dryers that reduce costs and carbon emissions.
Then electric hand dryers introduced things like HEPA filter technology, filtering the air they blasted out when hand drying. More recently, advanced electric hand dryers have been fitted with the same germicidal UVC light that hospitals use in sterilisation. Shining harmless UVC onto hands when hand drying really does zap bacteria, changing its chemical makeup and nullifying its chance of causing infection.
Finally, you have the Sterillo – the most hygienic electric hand dryer on the market today. The Sterillo takes the power of UVC light even further. When it’s not drying hands, the Sterillo continuously draws in bathroom air with a noiseless vacuum. It then blasts the air with germicidal UVC light inside the machine. In doing so, it kills the germs floating through contaminated bathroom air – also eradicating unpleasant bathroom smells in the process.
When it comes to hygiene, paper towels don’t come close.
“The economic and environmental cost of using bleached paper products is particularly high which has driven the marketplace to look for more cost effective alternatives.
The roller towel solved this problem [the roller towel was invented in 1933] and became very popular by giving a continuous feed of laundered towel for each consumer to use a fresh section. However, it too is expensive to use and requires regular service and maintenance with the towel rolls needing to be replaced and laundered frequently.
In 1948 the inventor George Clemens developed the first electric hand dryer which blew warm air through a nozzle allowing the user to place their hands underneath in the air flow. This was an effective and popular solution to hand drying, however, this would take at least 45 seconds to dry a pair of hands and was still quite costly in their electrical consumption.
More recently, high speed electric hand dryers have been developed which reduce the electrical cost by up to 85%. This is due to them working extremely quickly, typically drying hands in 10-15 seconds whilst using about half of the power needed by the older units. Halving the power and quartering the dry time gives a saving in excess of 80% of electrical cost and brings us to the point today where there is little to be gained from producing a more efficient hand dryer as any savings gained would be diminished i.e. is it worth spending an extra £200 to buy a more efficient hand dryer that might save you £3 a year in electricity?” Steve Levy, MD, Handy Dryers
“As a company, there’s nothing stopping us from selling paper towels or roller cloth towels. We’d probably benefit from offering them. The reason we don’t is we simply do not believe paper towels and roller cloths out perform electric hand dryers by any measure, whether that’s hand drying, infection control, cost or environmental impact.” Steve Levy, MD, Handy Dryers
On arguably the most important point, infection control, studies published as far back as 1991 have found electric hand dryers to be significantly more effective than paper towels and cloth towels when it comes to eliminating bacteria – and this was before we had high speed hand dryers and germicidal UVC light available when hand drying.
What is it that makes infection control the most important criteria in hand drying? In most circumstances, not much. But in the context of something like a hospital, infection control is clearly of utmost importance.
As anyone that’s used more than a few electric hand dryers will know, not all electric hand dryers are equal. A range of technologies and features mean some electric hand dryers offer benefits others do not.
HEPA filters are something to look out for. The air around us is filled with dust and dirt. Prolonged exposure to dust and dirt can irritate your lungs and contribute to allergies and asthma. HEPA filters, or high-efficiency particulate air filters, are essentially seriously advanced sieves that filter small, irritating particles in the air. When used in electric hand dryers, HEPA filters ensure hand dryers don’t fire dust and other pollutants directly at the user – which is particularly important when hand dryers are to be used by children.
There are two major categories of electric hand dryer: traditional and high speed. Traditional models are designed to dry hand through evaporation. They gently release hot air that, in about 45 seconds, dries hands. Unfortunately, using dryers for that long is about as kind to the environment as paper towels. Another major drawback is few users stick around for that long when hand drying, which means more wet hands, which means more bacteria.
High speed hand dryers, meanwhile, fire out air at high speed that whips water from hands in around 15 seconds maximum. They’re much more energy efficient and dry hands quickly – which means fewer wet hands and less bacteria.
Drip trays are also important. As we’ve already established, the residual water left on the hands after hand washing is full of bacteria. Electric hand dryers are going to remove that water, and the most efficient electric hand dryers do so by blasting the water from the hands. So where does the water (and the bacteria) end up?
If hand dryers have no drip tray, the answer is either on the hand dryer itself, on the walls and floor, or even on the person drying their hands.
Drip trays, like those used in sleek TOTO models, trap contaminated water. They prevent electric hand dryers from spraying bacteria all over bathrooms, and prevent the growth of mould some electric hand dryers promote.
Finally, you have germicidal UVC light. This is the same light used in the sterilisation of hospitals and hospital equipment, and can markedly increase the reduction of bacteria in hand drying. Electric hand dryers like the Gorillo use UV light to blast bacteria left on the hands following hand washing. Models like the Sterillo go even further, not just blasting bacteria during hand drying but cleaning contaminated bathroom air 24/7. It’s for this reason Raymond Martin, MD of the British Toilet Association and campaigner for better public toilets for all calls the Sterillo, “the most hygienic hand dryer available on the market today”.
The Sterillo room sanitising hand dryer and Sterillo Uno room sterilisation unit that remove offensive odours. Combining advanced germ killing UVC technology with a powerful hand dryers leaves washrooms with a massively reduced level of bacteria and smelling fresh.
Key criteria to consider are hand drying effectiveness, infection control, environmental impact, running costs and initial upfront costs.
On each, we’ll be reviewing in detail in further articles on our website but you can also find out lots of additional information by search through our existing blog articles and product information.
Our electric hand dryers are split into categories that signpost the way. The best thing to do is browse around. Or, if you’d like to speak to one of or team, we’re available from 9.00AM to 5:30PM Monday to Friday, (GMT, BST).