Are Hand Dryers Hygienic?

This post was last updated 4th September 2020

In view of the recent COVID-19 pandemic, this article has been updated to give you the latest information regarding hand dryers and coronavirus.

Yale School of Medicine state:

"Since threats like COVID-19 can lead to the circulation of misinformation, it’s important to trust information only from reputable health organizations and government sources such as the CDC and the WHO"

"Dry your hands completely. You can dry them under a warm air dryer, or use a paper towel. Avoid a recently used towel as moisture is a good breeding ground for bacteria, which makes drying your hands an important step."

In early March 2020, The World Health Organisation put out this message on the subject of hand washing:

"To protect yourself against the new coronavirus, you should frequently clean your hands with an alcohol-based hand rub or wash them with soap and water. Once your hands are cleaned, you should dry them thoroughly by using paper towels or a warm air dryer."

The CDC are quoted in this video:

"We have no evidence that hand dryers are spreading the coronavirus"

This is a great video from Royal Melbourne Hospital on how to protect yourself from COVID-19, saying dry after washing with either a paper towel or a hand dryer.

As of the 11th May 2020, the UK government has put out guidelines for a number of types of facilities to be “Covid-19 Secure” so that people can start to return to work in safe environments. Section 5 “Cleaning the workplace” specifically the “Hygiene: handwashing, sanitation facilities and toilets” part, states that “To help everyone keep good hygiene through the working day…Steps that will usually be needed:… Providing hand drying facilities – either paper towels or electrical driers.”

Kelly Reynolds, Ph.D., Professor and Chair of the Department of Community, Environment and Policy; Director of the Environment, Exposure Science and Risk Assessment Center (ESRAC) at the University of Arizona's Zuckerman College of Public Health has been quoted to say "Consumers may only read [sensationalized] headlines which can influence public opinion toward biased or erroneous conclusions, [but] the fact is, the breadth of data available does not favor one hand drying method as being more hygienic or safer." 

The quote is based on Reynolds et al (2020) scoping review - Comparison of electric hand dryers and paper towels for hand hygiene: a critical review of the literature 

There is certainly a need to question whether hand dryers are hygienic and if there is a safer way to dry the hands.  Especially because there seems to be constant headlines in the press aimed at why hand dryers are unsanitary, usually stirred up from paper towel manufacturers if you peek beneath the surface of the hype.

But are paper towels hygienic? This is something that doesn't get a lot of media attention yet there are studies conducted on paper towels from independent sources which have found that paper towels and their dispensers harbour a significant amount of bacteria and pathogens. 

Why wouldn't they, they're not made in sterile areas and they live in the same washrooms hand dryers do.  Neither is a harmful method of drying as you will read below, yet it doesn't follow logic that paper towels can be considered a more sterile and hygienic choice over hand dryers.

So, is this just a case of large, powerful businesses trying to manipulate public decision to keep its revenue streams flowing, even if it means manipulating the "facts" and peddling headlines and stories that are not in the public's best interest?

Isn't it a consumers right to choose one product over another, without trying to be influenced by ill-founded propaganda?

This post aims to:

1. Highlight why the paper towel industry is concerned about hand dryers
2. Give reason why lazy journalism and fake news needs to be scrutinised for allowing such meaningless propaganda to enter mainstream media outlets
3. Show you a couple of videos and other insights explaining why there is no need to be scared of using a hand dryer after reviews of the scientific research
4. Provide scientific evidence that adds balanced perspective to the paper towel and hand dryer germ debate
5. Explain why washing the hands properly and then drying the hands thoroughly, whatever the method of choice, is key to keeping things hygienic
6. Provide you with the history of how the hand dryer has developed to improve hand hygiene in the washroom

First of all, hand dryers or paper towels? Which is better?

This post is not here to slate paper towels in general although we will be biased to some degree of course.  The type of method used will be dependent upon the location and the unique requirements of the end user. We are just highlighting the point that hand dryers are getting a bad press due to the only way paper towel manufacturers can get at them.  By scaremongering and promoting germs.  We have already shown in our comparison of paper towels vs hand dryers here that when comparing the 2 methods:

1. Hand dryers are significantly cheaper to run year on year and can save substantial amounts of money compared to yearly costs of paper towels.
2. The most important aspect of hand hygiene is the hand washing process to actually remove germs, then making sure they are fully dry before touching anything else.  Whichever method you use as long as they dry, then that’s the main point
3. Paper towels create zero noise so are perfect for inside school classrooms and any other locations that require very low noise levels
4. Paper towels are not good for the environment, creating a massive amount of carbon to produce, and they cannot be recycled and mostly end up in landfill

Paper towel companies know the above can be proven through science and mathematical calculations, so continue to run with trying to discredit hand dryers as being a disaster to public health.  But as you will read, if you actually look between the lines and get all the evidence available, there is no real difference between paper towels and hand dryers when it comes to hygiene.

Interestingly, the Centres for Disease Control and prevention CDC which is part of the U.S. Department of Health & Human Services, state the following in their hand washing section. Their page was updated on a date after the last study conducted around this topic was published so I would hope is up to date with all evidence.

"Dry your hands using a clean towel or air dry them. Why? Germs can be transferred more easily to and from wet hands; therefore, hands should be dried after washing. However, the best way to dry hands remains unclear because few studies about hand drying exist, and the results of these studies conflict. Additionally, most of these studies compare overall concentrations of microbes, not just disease-causing germs, on hands following different hand-drying methods. It has not been shown that removing microbes from hands is linked to better health. Nonetheless, studies suggest that using a clean towel or air drying hands are best."

The CDC are also looking to be more conscious about the implications of waste using paper as they state:

"Turning off the faucet after wetting hands saves water, and there are few data to prove whether significant numbers of germs are transferred between hands and the faucet."

“While some recommendations include using a paper towel to turn off the faucet after hands have been rinsed, this practice leads to increased use of water and paper towels, and there are no studies to show that it improves health.”

Source: https://www.cdc.gov/handwashing/show-me-the-science-handwashing.html

There is also the science of why you should wash your hands thoroughly here https://www.cdc.gov/handwashing/why-handwashing.html

Why is the paper towel industry concerned and why choose hygiene?

The concerns

People are becoming increasing aware of the impact paper has on the environment including manufacturing, transporting, replenishing and disposing of.

Hand dryers used to be very inefficient.  Now they are comparable on dry times with paper towels.  Once they are installed there is no constant source of revenue for the paper towel industry.

The growth of hand dryers increases year on year.

Why hygiene?

The environmental impact and cost to purchase can not be disputed so the paper towel industry needed a different angle to create doubt.

Hygiene as a topic makes good headlines that resonate with a lot of people – makes them more newsworthy and sharable. Paper towels and hand dryers are boring, but the headlines that can be written to scare create excitement.

Many of the general public will not scrutinise the research or understand its implications so will be led by the media.  Although the research is performed under scientific conditions, it is the poor methodology and biased interpretation of the results to real world scenarios that creates the fear factor.

Interestingly the chairman of the European Tissue Symposium (ETS) a major representative of the paper towel industry and a funder of the most promoted pro-paper towel studies is quoted in the Guardian admitting when they fund a study they ask for “The title of the activity, the reason and key outline.” Scientific protocols – the design and implementation of experiments – are never discussed, he said. “Our member representatives are mostly business-background people. Details of a protocol are not an interesting subject to them.”

To me this shows it doesn’t matter if it’s relevant to real world scenarios or if the methodology is poor and interpretation biased. As long as they give their members ammunition to use as a sales tool, that will do for them. They know their members won't read the actual scientific studies to critique and analyse. They don't need to as they feel they can trust the organisation that represents them all.

By targeting hospitals, it suggests that concerns should be made by all society in every walk of life. 

A good point to think about is although hand dryer installs are growing year on year, the UK Office for National Statistics (ONS) reports a dramatic fall in the amount of absence from work from 1993 to 2017.  Granted there are other reasons for this but surely if there was so much of a problem there wouldn’t be this kind of decline?

What’s the impact on society?

Wrongly, public opinion is being diverted away from the bigger issue.  The reality of climate change and the negative effects it is having.  Big business is trying to manipulate public opinion for profit, when in fact it is against public interest to ignore the environmental impact of paper.

Hand dryers use very little energy so are better for the environment.  They can also save businesses, schools, hospitals etc a large amount of money that can be better used.

Is there a place for paper towels?

Yes of course.  They create no noise so are perfect for inside school classrooms and any other location that require very low noise levels.  They also require no electricity when in a washroom, so for areas that cannot have electric circuits they are vital. The key to overall hygiene is being able to dry the hands, so a method needs to be in place to do this.

It should come down to preference and suitability for the location.  If people prefer paper towels then they should be free to choose based on correct information, not spinning of poor or conflicting science. 

However, now that there are hand dryers that perform just as well, people’s perception of the low waste, environmentally friendly option of the hand dryer is a legitimate contender to the drying experience.

Should you believe everything you read about hand dryer germs?

A lot has been publicised in newspapers such as the Telegraph and Mail including paper towel industry funded research into the debate of which hand drying method is the most hygienic.  The NHS has commented on these published articles here and here, which draw conclusions that they do not give adequate information in terms of validity, limitations etc to make substantial and creditable headlines and claims.

The scientific studies are littered with words like "potential" and "possible" yet media would have the world believe they are fact.

An interesting impartial journalism piece in the Guardian has arisen recently which puts the “war” between paper towel and hand dryer’s into some perspective.  The major things I took from the article were:

• Before the launch of the Dyson Airblade, and innovations of Mitsubishi there was no real competition to “big towel.”  The towel companies dominated hand drying and also had large market share over other products so their profits were massive compared to much smaller hand dryer companies.
• Between 2012 and 2020, a Dyson spokesperson reckoned, hand dryers will have sucked $873m out of paper towel revenues
• The author writes “Science has tried and failed to come to a consensus about the hygienic superiority of one product over the other. Even so, the paper towel industry has funded or promoted a rash of studies claiming that hand dryers turn bathrooms into mosh pits of pathogens. These results almost always make news. Any sort of health scare is a gift to a journalist – an opportunity to write viral headlines” “It isn’t easy to know what to make of these studies. Many undergo peer review, but an experiment can be structured in a way that favours a particular outcome and still be valid science”
• The research and development that goes in at Dyson is so secretive and NASA like, do you really think they would have let this slip through the net and put something unhygienic on the market?
• Before paper towel funded research is actually conducted, a media strategy for the best-case scenario is already put together! A PR firm representing the paper towel industry is quoted as saying “‘What’ and ‘If’ are two words as non-threatening as words can be. But put them together … and they have the power to haunt you for the rest of your life: what if?” The budget for the media plan of a funded study ran to €30,000.  This is BEFORE the study was even conducted.  How can they be that confident they would have a story to run if they hadn’t “influenced” the outcome already with the scientists they have on their books?
• The author states “Our loo culture reveals our habitual laziness, our perpetual hurry; it is our own tendencies, rather than hand dryers or paper towels, that must be blamed for our germ-ridden restrooms”
• One of the major researches on a paper towel funded study is asked what he would do if there was only a hand dryer in a bathroom, “I’ve always got … ” he began, then started digging through the pocket of his coat. A jingle of keys emerged, then some coins, and finally, a crumpled sheet of paper towelling.” The sterile area of the pocket, keys, and coins will surely keep that old piece of paper sterile wouldn’t it?…..

To read the full article, see here:  Hand dryers v paper towels: the surprisingly dirty fight for the right to dry your hands

The most recent studies and the misleading headlines that came from them

We believe in reading the scientific literature to analyse the findings of these studies and how they match up to the headlines that are being put out there.

Here are 2 most recent studies that have made the headlines and our analysis of them.

Study 1. Deposition of Bacteria and Bacterial Spores by Bathroom Hot-Air Hand Dryers

Media example

Headline: "The bacterial horror of hot-air hand dryers"
Source: Harvard Medical School

The headline suggests a slightly scarier scenario than the author actually concludes, showing an agenda to bias the public opinion. The conclusions they made as follow are a little more realistic and should never have created such a headline:

• “The vast majority of the microbes that were detected do not cause disease in healthy people, with the exception of Staphylococcus aureus. Some of the bathroom bacteria, such as Acinetobacter, only cause infections in people in the hospital, or in those with weak immune systems. The others that were found are relatively harmless.”
• “In addition, air from real-world bathrooms may contain fewer bacteria than the bathrooms in the study. The sampled restrooms were located in a university health sciences building, and at least some of the bacteria came from experiments going on in laboratories within the building.”
• “Remember that your chances of picking up a serious pathogen in a restroom are small. Direct contact with other people is much more likely as a means of acquiring infection.”

You tend to find that the headlines in most articles are not in line with the conclusions made that hand dryers are indeed safe to use. Another example of this is:

Headline: “The reason you might want to stop using public bathroom hand dryers for good”
Source: msn.com

The conclusions in the actual article are:

• “However, according to Paul Suits, director of Infection Control at Upstate Medical University, hand dryers are safe to use. “Most people aren’t going to get sick [from hand dryers] because most people are healthy. So it’s not an issue,” Suits said. Suits further explained that people should be more concerned about the germs that stay on their hands from not drying their hands properly. “If you don’t completely dry your hands, it won’t kill all of the bacteria.”

Other headlines:

Headline: "Hand dryers can blow fecal bacteria onto your hands, a study found — and the researchers are now switching to paper towels"
Source: Business Insider

Headline: "Hand dryers suck in fecal bacteria and blow it all over your hands, study finds"
Source: USA Today.com

Our analysis:

• The key words being used in a lot of these media articles are “perhaps” and “suggests”.  This is speculation and not reflected in some of the headlines
• No faecal matter was found to be blown on the hands, it was just suggested this could be an area to further investigate, yet some led with this headline.
• A good proportion of bacteria found in the study was that which was grown actually in the research facility which skewed the results
• This is just a suggestion that if pathogens are in the air there is potential for them to be blown onto the hands by hand dryers.  However, this is air that is being breathed in all the time.
• Petri dishes exposed to hot air from a bathroom hand dryer for 30 seconds grew up to 254 colonies of bacteria (though most had from 18 to 60 colonies of bacteria).  Significantly less than that found on unused paper towels and everyday items (See section below "How does the number of bacteria found on everyday equipment measure up to that found on petri dishes?)
• Any reference to C.diff and “toilet plume” was purely speculative yet other headlines promoted faecal matter as being spread over the hands. They stated the role of this potential mode of C. difficile transmission is worthy of future study, however the references they used included those that measured air only 25cm above a toilet or next to a hospital bed. Pure speculation yet the media ran away with "clickbait" stories.
• This article https://qz.com/1207418/using-an-air-dryer-after-you-wash-your-hands-may-just-make-them-dirtier/, interviews another researcher from the same study who states “in general, the findings don’t present enough of a concern for everyone to switch to using paper towels. Although there may be more bacteria floating around the air, most of these potential pathogens are no match for a healthy human immune system”. 

Study 2. Environmental contamination by bacteria in hospital washrooms according to hand-drying method: a multi-centre study

It is important to note regarding this study:

1. Conflict of interest statement: M.H.W. has received honoraria from the European Tissue Symposium (ETS) for microbiological advice and lectures, and travel expenses to attend meetings. F.B. has received honoraria from ETS for microbiological advice and travel expenses to attend meetings.
2. Funding sources: The ETS funded the project; conception, design, results analysis, and manuscript preparation were carried out by the authors.

This was a study funded by the ETS, a representative of the major companies of the paper towel industry, and used scientists who have received rewards for providing work for the paper towel industry.

Media example

Headlines: “Jet air dryers spread viruses and bacteria from unclean hands, study finds”
“Dryers can create an "aerosol that contaminates the toilet room" when people do not wash their hands properly before using them.”
Source: Sky.com

Our analysis:

• Staphylococcus aureus has been used to glorify the media articles, with them stating that there are 3 times more of this bacteria in a bathroom with a hand dryer than a paper towel. “3 times” sounds a lot but the actual levels found were said as being “low, “very low” or “no” by the authors of the study when comparing hand dryer and paper towel bathrooms.
• The methods were very biased towards testing hand dryers:

1. No mention of where the paper towel dispenser was situated relative to the wash basin – closer to the sink so less drips on the floor?
2. No measurement of the amount of bacteria around where the paper towel was deposited – yet samples taken from the floor of the hand dryer (a no touch area)
3. Most bacteria relating to the hand dryer was on no touch areas; the hand dryer itself and the floor. (It doesn’t matter where sample was taken from, they are not touched at all).
4. The study gives no idea of where the sample on the paper towel dispenser was taken from – was it the opening of the paper towel dispenser where contamination has been found (see below)? Or was it just the outside casing of the dispenser?

• The hands were not tested and there were very low amounts of bacteria in the air. Air amounts of bacteria were the same in both conditions, yet conclusions from the media included that the hand dryer created an "aerosol".  This conclusion more than likely came from previously flawed research. See the Dyson video below
• The study states that “c.difficile was not recovered from any samples in any country”. But wouldn’t this have been found as was suggested in the study referenced above that "toilet plume" can reach the hand dryer? - see Deposition of Bacteria and Bacterial Spores by Bathroom Hot-Air Hand Dryers above.
• The study concluded “It is possible that different behaviours before hand-drying could affect the extent of environmental contamination. For example, people about to use a JAD (jet air dryer) may shake their hands (dispersing water droplets) to remove excess water. We found higher bacterial contamination from JAD surfaces and floors, which is consistent with such behaviour, but this contamination could then be increased due to the way the dryers function.” The scientist admits limitations in their methods yet collect samples from areas they say is a natural source of water dispersal from the user, nothing to do with the hand dryer. They also speculate on the function of hand dryers, this wasn't assessed in the methods.
• All sample locations were totalled up for bacteria counts to present their findings (even though it was biased towards where samples were taken from around the hand dryer) This made bacteria counts seem higher in the hand dryer washroom, but as stated it included areas that people do not touch e.g. the floor and the case of the hand dryer.
• The waste bin area where paper towels end up not was not tested. If the floor and the casing (no touch areas) around the hand dryer are considered hygiene issues then why not this area of contamination? This would have created a larger bacteria count for the paper towel days of the experiment and therefore created a balance in number of bacteria found?
• The study doesn’t show if they tested the exit of the paper towel dispensers, which have been shown to be a contamination point - Bacterial transfer and cross-contamination potential associated with paper-towel dispensing - or just a random part of the casing. Again, this would surely have created a larger bacteria count for the paper towel days of the experiment and therefore created a balance in number of bacteria found?
• The media have said that bacteria is spread because we do not wash our hands properly, suggesting that this is why this study is important.  However, as you will read below, bacteria can zig-zag transfer from hands to paper towel dispenser exit and back to hands.  So, this is a problem for any washroom? Not just those with hand dryers.

Interestingly, after the study was published and all the worrying headlines, www.abc.net.au do quote one of the main researchers Professor Wilcox saying:

"Bugs can be transferred from your hands to other surfaces much more easily if your hands are wet or damp.

"So it's better to use a jet air dryer than not dry your hands at all."

Here's a further look at the credibility of the evidence and the case against some articles and reviews

A review of both methods of hand drying titled "The Hygienic Efficacy of Different Hand-Drying Methods: A Review of the Evidence" stated that “from a hygiene viewpoint, paper towels are superior to electric air dryers. Paper towels should be recommended in locations where hygiene is paramount, such as hospitals and clinics.”

However:

• Although 12 studies were reviewed, they showed very conflicting results in all the studies when it came to paper towels and hand dryers, yet it is concluded that hand dryers are significantly more unhygienic than paper towels?
• Even though the review presents a balanced view, the study they deem to be the best is an ETS (paper towel industry) funded one on many occasions.
• One of the reviewers has served as an occupational health and safety consultant for Kimberly-Clark, Sydney, Australia.

This looks to show bias to a paper towel industry funded paper.  It also shows a potential conflict of interest from a previous consultant to one of the largest paper manufacturers on the planet.

The NHS provide an analysis by Bazian, edited by NHS Choices on this review and state the following limitations:

"This review suggests that using paper towels to dry the hands is more effective than other methods at actually getting the hands dry, reducing the amount of bacteria on them, and preventing contamination of the washroom environment.

There are, however, limitations to this review that should be considered before concluding that hot air dryers or jet dryers are ineffective:

• The review did not report the quality of the various studies included. When determining whether the results of a study are valid, it is important to establish whether the research methods were sufficient to minimise bias and confounding. As the review did not report this, it is unclear how valid the studies' results are.
• The studies' methods varied and this could influence the consistency of results across the experiments. The amount of time spent drying, the method of measuring bacteria levels and other differences may account for the variation in results.

Identifying hygiene behaviours to help minimise the risk of cross-infection has become increasingly important. Much research has gone into the most effective hand washing techniques. The good news is that, whatever the limitations of the review, its findings support current hand washing recommendations.

This review suggests that paper towels are the best option for settings where containing infections is critical, and may be more effective than hot air dryers.

However, if you have no choice – as is the case in most public toilets and workplace washrooms – and only hot air dryers are provided, take extra time to dry your hands thoroughly. There is little evidence that they are any worse than hand towels, other than the extra time spent drying your hands."

A more recent (2018) review of the research around this topic, states the following:

“This review found there to be little agreement regarding the most hygienic method of hand drying and the published evidence regarding whether hand drying methods vary in their efficacy or tendency to aerosolise and thus transmit microorganisms is inconsistent.”

This review does state its own limitations in that it didn’t delve deeper into the methodologies of the studies used in the scoping article, it relied on the reporting of the results from each reports author rather than their own conclusions.  However, I suspect that if they did, they may be able to see the biased way some of the studies are set up and unrealistic in nature.

It needs totally independent studies to be conducted before any meaningful conclusions can be made.  Although you usually see, as in the review mentioned above and studies you will see below, when independent research is carried out there is usually no difference in the hygiene levels of both methods found.  Not very exciting for these scary headlines is it?

A more balanced view can be seen below.  It gives a very good account of how to look at this debate as well as best practice for hand drying in general:

Key points from the above video:

• A lot of studies that claim paper towels are better than hand dryers are funded by paper towel companies, how trustworthy can this be?
• Paper towels are more harmful for the environment
• Wet hands easily transfer far more bacteria than dry ones, germs love a wet breeding ground
• Don’t wipe wet hands on your clothes or touch any surface before they are fully dry as you will just pick up a load of bacteria and may as well not washed them at all
• Paper towels can actually harbour bacteria, with recycled hosting more.  This is due to paper towel holders not being sterile as well as paper being made in a factory which again is not a sterile environment
• Paper towels and high-speed hand dryers can dry your hands as effective and as fast as each other
• If people actually washed their hands properly it doesn’t matter which method is used regarding bacteria transfer – a study showed that only 5% of people correctly wash their hands to actually get bacteria off the hands

So, if people wash their hands properly is one drying method better than another for making sure bacteria is removed from the hands? No statistical difference found between cloth towels, paper towels, warm air hand dryers and leaving to dry naturally for removal of bacteria from hands.  Get them washed properly first!

CDC - "Keeping hands clean is one of the most important steps we can take to avoid getting sick and spreading germs to others. Many diseases and conditions are spread by not washing hands with soap and clean, running water."

Dyson have published their own response to the scientific articles which have been produced:

Key points from the above video:

• Studies were commissioned and paid for by the paper towel and cotton towel industry
• Washing is the key to bacteria removal, drying is then the preventative measure to make sure bacteria doesn’t spread around from place to place with germs loving to hop on a wet hand to travel and grow.
• Using a Dyson Airblade reduces the transfer of bacteria by up to 40%
• Using a hand dryer like the Dyson Airblade puts fewer bacteria in the air than taking your coat off
• Even though studies commissioned used unrealistic methods - a vast amount of bacteria are added to the hands in some studies, a far greater amount than would even be found on the hands anyway - only a very small amount of bacteria was transferred into the air.  Levels of bacteria blown about are shown to make an insignificant contribution to bacteria that is already in the air around you all the time.
• Studies that have been commissioned by paper towel companies that show there is no difference in the amount of bacteria put in the air using paper towels or Dyson Airblade’s have been published in scientific journals but have never been chosen to be reported in the main press.
• There is just as much bacteria found on a tap, hand dryer, paper towel dispenser and door handle.
• 1 in 5 paper towel dispensers can be found empty.  If there is no paper there is no way to dry the hands.  Damp hands spread up to 1000 times more bacteria than dry ones
• Bins full of paper towels create an area full of germs.  These can overflow and create an unhygienic environment.  Hand dryers do not need this constant maintenance to keep hygiene levels up.

Examples of Studies that show no difference in hand drying methods

Study: Effects of 4 Hand-Drying Methods for Removing Bacteria From Washed Hands: A Randomized Trial 

Abstract: “The difference was determined between the amounts of bacteria on hands artificially contaminated with the bacterium Micrococcus luteus before washing with a nonantibacterial soap and after drying by 4 different methods (cloth towels accessed by a rotary dispenser, paper towels from a stack on the hand-washing sink, warm forced air from a mechanical hand-activated dryer, and spontaneous room air evaporation).”

“Conclusion: These data demonstrate no statistically significant differences in the efficiency of 4 different hand drying methods for removing bacteria from washed hands.”

Study: A comparison of effect of three hand drying methods on washed hands

Abstract: “The aim of the present study was to evaluate hygienic efficacy of the three different hand-drying methods (paper towels, cloth towels, warm air dryers).”

“Conclusion: This study shows that warm air hand driers, of the type used in this study, are a hygienic method of drying hands and therefore appropriate for use in the healthcare. Both warm air driers and paper towels gave acceptable and comparable results.”

But are paper towels hygienic?

Studies on paper towel hygiene that do not receive much media attention

We are not saying that paper towels are harmful to you, we are just putting some perspective to the debate looking at other research that's out there. 

The studies below may be open to debate, but the fact remains that sensationalised press releases about hand dryers are certainly manipulated and quickly circulated faster and more intensely than anything below, which are just as relevant to public health.

Paper towels are not made in sterile environments so why would they be free of bacteria?

Study: Evaluation of bacterial contaminants found on unused paper towels and possible postcontamination after handwashing: A pilot study

Up to hundreds of thousands of bacteria are actually located in a paper towel yet to be used, with the bacteria capable of transferring to wet hands when being used. When you look at the research aimed at hand dryers the number of bacteria found is usually in the tens to low hundreds, generally taken from a larger sampling area too. 

Study abstract: “Between 10² and 10⁵ colony-forming units per gram of unused paper towels were isolated from the different paper towel brands. Bacteria belonging to the Bacillus genus were by far the most abundant microorganisms found (83.0%), followed by Paenibacillus (15.6%), Exiguobacterium (1.6%), and Clostridium (0.01%). “Conclusion: This pilot study demonstrated that a large community of culturable bacteria, including toxin producers, can be isolated from unused paper towels and that they may be transferred to individuals after handwashing. This may have implications in some industrial and clinical settings as well as in immunocompromised individuals”

Key points: 100 to 100,000 bacteria found per gram of unused paper towel (approx. 2 paper towels – average per dry) – some that can be pathogenic – which can be transferred to the hands when used

Paper towel dispensers get touched when pulling out the paper

Study: Bacterial transfer and cross-contamination potential associated with paper-towel dispensing 

Wet hands reaching into dispensers to unblock them leaves a wet, damp environment for the next user.  An environment ideal for bacteria to grow in. 

It has been shown that bacteria can be transferred from the zig zag of hands to paper-towel dispensers and back again.  This occurs when people often have trouble taking paper towels from the dispenser exit and touch the unit itself.  A common process in reality.

In this study it states “Paper-towel exits from folded paper towel dispensers located at handwash stations in food processing facilities have been found contaminated with Eshcerichia coli.  More recently, studies have indicated towel dispenser exits in hospitals are often not included in routine cleaning and are contaminated.” (Page 390, column 1, lines 12-17.)

“Conclusions: The results indicate that zig-zag transfer of bacteria between paper-towel dispensers and hands can take place if either one is contaminated. This potential should be considered in the design, construction, and use of paper-towel dispensers. (Am J Infect Control 2003;31:387-91.)”

Key points: The study metioned above in the section "Should you believe everything you read about hand dryers and germs?";Environmental contamination by bacteria in hospital washrooms according to hand-drying method: a multi-centre study https://www.journalofhospitalinfection.com/article/S0195-6701(18)30366-9/fulltext doesn’t show if they tested the exit of the paper towel dispensers.  The author (Wilcox) has stated in press that people don’t wash there hands properly and a reason why the study was important.  However, the transfer of any bacteria on the hands to the paper towels via the hands entering the dispenser is possible if not washed correctly and creates bacteria transfer.

Some paper towel dispensers have touch points to release the paper

Study: University of Buffalo student study 

Article headline “UB researchers find high-speed hand dryers are six times cleaner and produce 42 percent less carbon dioxide than paper towel dispensers. The students found that six times more bacteria grew on paper-towel dispenser push-and-crank handles than on the Airblades.”

It's been found that six times more bacteria grew on paper-towel dispenser push-and-crank handles than on the Airblades. Manufacturers are constantly bringing out touchless systems with captive refills so they can keep prices high in the face of lower cost hand towels, the fact is that the majority of buyers still want to buy cheap' so most dispensers are touched.

Key points: Hand dryers are “no touch” which reduces cross contamination points.

If there isnt any other drying method around people will use toilet paper

Paper towel dispensers are no use if they are empty and people will look to other methods if this is so.

Article: "Research Finds Average Toilet Paper and Towel Dispensers Have More Bacteria Than Average Toilet Seat" 

Although not a link to a scientific paper the scientist has been quoted a number of times in other reports which these statistics

“According to new research conducted by microbiologist Charles Gerba, of the University of Arizona, the average toilet paper dispenser has more than 150 times the amount of bacteria than the average toilet seat. The picture isn't much improved when it comes to paper towel dispensers. These were found to have over 50 times more bacteria on average than a typical public restroom toilet seat”

How does the number of bacteria found on everyday equipment measure up to that found on petri dishes?

At the office

Other things to consider when looking at this research regarding hand dryers is that the amounts of bacteria found were so significantly less than everyday items, such as those found in the office we come into regular contact with. Millions of bacteria per square inch are found on everyday items.

To put this in perspective, research by EMLab P&K, highlighted by CBT Nuggets found that there are:

• 4,620,000 bacteria units per square inch on an ID badge
• 3,543,000 bacteria units per square inch on an office keyboard
• 1,600,082 bacteria units per square inch on a mobile phone

Out of this, 42% were bacteria that cause strep and staph infections and 21% was bacteria resistant to antibiotics, whose group include MRSA.

It is interesting to note that the study mentioned in the section “Should you believe everything you read about hand dryers and germs?” which looked at germs in a hospital visitor toilet was not only selective in where it measured samples from but also its sample size was 15.5 square inch with an average of just 163 bacteria units around hand dryer and floor.

Bigger sample area yet significantly fewer bacteria than every day office equipment!

University computer keyboards

Study: Microbial contamination of computer keyboards in a university setting 

“Overall, a greater number of microorganisms was detected on the keyboards of the multiple-user computers, with an average of 20.1 colonies per square centimeters, whereas the single-user keyboards had an average of 4.5 colonies per square centimeters. Forty-seven percent of multiple-user keyboards were found to harbor Staphylococcus aureus, compared with only 20% of the single-user keyboards. Of particular interest was the isolation of bacteria belonging to of the Enterobactericeae family, including Escherichia coli from one keyboard, as well as Enterococcus faecalis, which is indicative of fecal contamination. Conclusion: In summary, this study has demonstrated that microbial contamination of multiple-user computer keyboards may be a common mechanism of transfer of potentially pathogenic bacteria among users.”

Student mobile phones

Study: High level bacterial contamination of secondary school students’ mobile phones

Results “found a high median bacterial count on secondary school students’ mobile phones (10.5 CFU/cm2). Potentially pathogenic microbes (Staphylococcus aureus, Acinetobacter spp., Pseudomonas spp., Bacillus cereus and Neisseria flavescens) were found”

The fact of the matter remains.  The most important aspect of hand hygiene in the first place is actually washing the hands in the right manner, for the correct duration. This ensures that germs are actually removed from the hands using the best substances for the job, soap and water.  

Then ensuring that the hands become completely dry, whatever the method of drying, is the next essential step, so the hands aren't open to pathogens as you leave the washroom and on other equipment you come into contact with.   

The history of hand dryer hygiene

In summary, this is a historical timeline of how hand dryers have evolved to enhance hand hygiene with various methods:

• Commercial, warm air hand dryers were under constant testing as it is thought they were a breeding ground for bacteria
• High speed hand dryers were introduced, without heater elements, quicker at drying the hands and therefore diminishing wet hands (the breading ground of germs).  Antimicrobial materials were also used in the making of the hand dryers
• The HEPA filter was invented, which filtered the air being sucked into the hand dryer of dirt and bacteria, making sure clean air is blown over the hands
• New technology has been added to the HEPA filtered hand dryer to actively clean the filter, because if a HEPA filter is not maintained and serviced regularly, dirt can build up and render the filter ineffective.
• We are currently looking at a number of new technologies that specifically draw the air from a sterilised source. 

The Advances in Hand Dryer Technology

Traditional commercial hand dryers

This type has a low speed motor (RPM revolutions per minute of between 2000 and 7500), relying on warm air to evaporate water off the hands. Dry times can be anything between 20 and 50 seconds.

Wet hands transfer germs easily and the longer the dry time the less likely someone is going to wait until their hands are fully dried. This was a big plus for the paper towel industry.

The paper towel industry always argued that hand dryers heat up bacteria and blow it onto the users hands. There have been many studies, although the extent of bacteria protection has varied considerably depending on who commissioned the study. There were counter studies that showed if the airflow was heated enough, this was enough to kill the bacteria rather than multiply it.

All in all, traditional hand dryers were cheaper, more eco-friendly, required less servicing and kept washrooms tidier, but certainly lost out when it came to effectiveness.

The new breed of hand dryers

First we had high speed, hands under hand dryers that relied on air speed as opposed to heat, the first of which was the Xlerator. These were certainly much more effective at drying hands thoroughly. Then along came the Airforce hand dryer from World Dryer. This had no heater element and had antibacterial plastics and a filter to prevent the unit from clogging up with dirt.

Even earlier, Mitsubishi launched a completely new concept ‘the blade hand dryer’ called the Jet Towel. The Jet Towel was available in a non-heated version and dust and dirt was filtered creating a cleaner dry. The Jet Towel was not seen in the UK market until the early part of 2000 and wasn’t widely adopted; presumably as it just didn’t look like a hand dryer was supposed to at the time and they didn’t market the concept as effectively as Dyson.

Dyson put some serious resources behind developing and marketing their own clean air, high speed hand dryer and gained NSF approval for the Airblade. The P335 protocol was developed in conjunction with Dyson as a way of testing hygiene and dry speeds. It was certainly a big positive for the industry to establish a credible protocol. 

The Mitsubishi Jet Towel and Jet Towel Smart are now both NSF certified.  They also have an antibacterial resin injected into their plastic parts.

Other hand dryer manufacturers have followed suit by incorporating HEPA filters and antibacterial surface protection, some have even innovated further. The issue is that not many hand dryer manufacturers can afford to pay the large fees NSF required to officially test with the NSF and become certified and a similar more affordable approval needs to become available. Tests also need to be longitudinal, to test the continued protection the new breed of hand dryers offer.

You can see that modern hand dryers have come a long way from the warm air versions that the paper industry had a field day with. Hand dryers are now fast drying, environmentally friendly and help maintain cleaner facilities.

To view a range of hand dryers with enhanced hygiene properties, please click here

You will see on these hand dryers a cost calculator that will compare the running costs and the payback period against paper towels, as well as the amount of Carbon saved.

We have recently launched a hand dryer tap which draws its airflow from the cavity under the sink. We are researching whether sterilising the airflow in this enclosed space could offer an enhanced level of hygiene. Normally using UV-C technology for the airflow of a hand dryer is completely inaffective as the speed the air passes over the UV-C is too fast to sterilse, also its not the safest application to have ozone produced within a dryer as its at the height where it will be directly inhaled. However if you sterilise an enclosed space where the air is being drawn from their is potential to create a product that will be interesting to clinical environments where extra precaution needs to be taken. 

In summary

• Modern hand dryers and paper towels are a very effective way of drying the hands, vital for hand hygiene.
• The modern hand dryer provides substantial environmental improvements and cost savings.
• Paper towel manufacturers concerns have led to scientific studies being commissioned to try to put doubt regarding hand dryer hygiene.
• The scientific literature varies in its conclusions yet certain aspects are fed to the media. People rely on the media to give facts and will not scrutinise the actual science. The paper towel industry knows this.
• "Clickbait" headlines entice readers and influence public opinion yet most of the articles conclude that there is nothing to worry about.
• Paper towels and their dispensers are not free from bacteria, proven by the scientific literature.  As per hand dryers, these pose no threat to public health but it’s not peddled to the media to cause sensation like the hand dryer ones are.
• The key message for hand hygiene is to make sure the hands are correctly washed and then fully dried, whatever the method of choice

Written by: James Marvin

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