13-Year-Old Scientist's Research Shows Hand Dryers Can Hurt Kids' Ears

[schoen]

Previous discussion: https://news.ycombinator.com/item?id=20282837

[m3at]

Relevant thread on the same subject from two weeks ago:

https://news.ycombinator.com/item?id=20282837

[maddyboo]

Hand dryers need to die.

Their primary benefit is lower cost of operation for the facility, but other than that, their environmental impact is at best marginally better than paper towels, and worst is their hygienic aspect.

Various studies have found up to a two-fold increase in bacteria count on users' hands, as well as a risk of contaminating the surrounding area with bacteria blown off of the user's skin:

"In 2009 a published study was conducted by the University of Westminster to compare the levels of hygiene offered by paper towels, warm air hand dryers and the more modern jet-air hand dryers. It found that after washing and drying hands with the warm air dryer, the total number of bacteria was found to increase on average on the finger pads by 194% and on the palms by 254%; drying with the jet air dryer resulted in an increase on average of the total number of bacteria on the finger pads by 42% and on the palms by 15%; and after washing and drying hands with a paper towel, the total number of bacteria was reduced on average on the finger pads by up to 76% and on the palms by up to 77%." [1]

The noise aspect discussed in this article is yet another reason air dryers need to die. I hadn't even considered the effect they might have on kid's ears, and I'd imagine most adults probably haven't thought about it either. I find them positively annoying, but having your ears at the same height as these monstrosities must be horrible.

Kudos to Miss Keegan for her wonderful research!

1: https://en.wikipedia.org/wiki/Hand_dryer

[vkou]

> Various studies have found up to a two-fold increase in bacteria count on users' hands,

I take issue with the nature of that statistic.

What does a 'two-fold increase' actually mean? Is it two hundred bacteria, instead of one hundred, when pre-hand-wash, I have millions?

Is it double the bacteria after use, compared to before use? If so, how many bacteria do I even have, after washing my hands?

What is the quantifiable harm of this 'double'? Double times 'next to nothing' is still 'next to nothing'.

(I despise hand-dryers, but I also take issue with these sorts of claims.)

[mlurp]

Not that I want extra bacteria, but I wonder how significant that increase is practically, or what the baseline is. I'll sometimes shake a dozen peoples' hands in a row if I'm at a party, or hold onto public transport rails... Can it be much worse than that?

[Waterluvian]

I don't know enough to be informed but I'm naturally skeptical about this idea that germs == bad. Maybe a washroom is an autoimmune proving ground for my body.

I think what might help is some better sense about what the pros and cons are to exposure. Are there some germ sources you want to avoid while others you can probably be fine with? Should my kid really wash his hands after visiting a playground?

At the moment all I see is that germs are lumped into one category and treated as a quantity to eradicate 99.9% of with lysol.

Or put simply, why should any of the numbers in your comment be seen as a bad thing?

[sbr464]

Regardless of the research, I think what’s not discussed is how the choices around these devices are typically made by a single owner of a business. As the population continues to increase, and people generally become more educated and these types of experiences have more value, how could we come up with either solutions to the core issue, or solutions to give more funds to a business owner who would gladly install a better solution if those funds were available?

Taking a sample of a hundred random people, especially in a larger city, their values (however ranked) are wildly different, yet one person likely made the decision on the dryer, dependent still on the strengths of the local paper (janitorial supplies) company’s salesperson.

Currently, there isn’t a micro donation or registry (wedding registry) type framework where people can influence these decisions. Something similar could be in store?

Even Kickstarter, while it allows popular ideas to move forward, doesn’t allow these types of decisions to be influenced.

[js2]

> marginally better than paper towels

Of which you need only one to dry your hands:

https://www.ted.com/talks/joe_smith_how_to_use_a_paper_towel

[npunt]

There are tons of hand dryers in hospitals. Completely self-defeating, facepalm-worthy infrastructure.

[zeta0134]

> In response to these results, Dyson confirmed to NPR in an email that an acoustics engineer would be meeting with Nora to discuss her research.

You go girl. Rock on! No matter what happens, what an awesome response from Dyson to look at this girl's well thought out research and go, "Huh. Yeah, we should probably give that a second pass."

[jhanschoo]

It can be made into a positive thing: e.g. hand dryers with attention paid towards being comfortable for childrens' ears, marketed especially toward early education institutions and the like.

[ddingus]

Seconded! Very well done.

[Jonnax]

I don't understand why they have to be so loud.

I recently bought a Miele vacuum cleaner, and compared to other cheap vacuums I've had before. It's significantly quieter whilst still having effective suction.

Is it cost cutting or is this the best kind of motors possible for hand dryers?

As a side note: I wonder what the testing conditions are like for these dryers. Like there's one of the Xcellerator driers at my local bouldering place's toilet.

It's a very small tilled room. I went once and the sound caused my ears to ring for hours.

I don't go in without my noise cancelling headphones now haha.

But I imagine if the room was a lot bigger that would not be an issue.

[skosch]

Wild speculation: I wonder whether loudness is actually a design goal, to make the dryer appear more powerful. A sizable number of people are skeptical of electric vehicles, because they perceive an earth-shaking vroooom to be an essential part of the driving experience. Could someone with industry experience chime in?

[skrebbel]

Loud machines are loud because loud is the easiest. It takes serious analysis and engineering to discover exactly where the noise comes from and/or is amplified and fix that. Sometimes you can cut a machine's noise level in half just by tightening a few screws or replacing some raster by a different material, but you don't know which one until you detect where the noise comes from.

Your Miele is less noisy because they (and their suppliers) invested lots of engineer hours in making it less noisy, both at the motor level and at the level of the entire vacuum cleaner.

[sneak]

I am pretty sure it is just cost; after all, places install them to save on consumables cost and staff to periodically refill towels and empty the trash.

[xbmcuser]

A few days ago someone posted on hackernews about about noise canceling shapes I wonder if that can be used to muffle such sounds. Using architecture to expand or muffle sounds has been used for centuries but sadly we have stopped using them much because of easy availability of electronics.

[sarego]

I read the previous post on this that appeared on HN a couple of weeks back. https://news.ycombinator.com/item?id=20282837

My 3 year old used to close her ears anyways when near any of these hand dryers but now i warn her when one is about to turn on.

[wmeredith]

“In response to these results, Dyson confirmed to NPR in an email that an acoustics engineer would be meeting with Nora to discuss her research. “

Good for them. And good for her. My son (4) hates these things. He dries his hands on his shirt instead.

[spankalee]

My 4.5 year old son will not let me use them. He'll throw an absolute fit if I try. I have a lot more sympathy for that now!

[lunchladydoris]

My son, now five, has hated them for years. He dries his hands on my shirt instead...

[jrrrr]

Mine too.

[mrfusion]

I’ve been suspicious of this for years. These things are incredibly loud and they’re right at ear level for kids.

[senectus1]

My 11yr old son has been complaining about them being way to loud for him for years as well... I think I own him an apology for not taking the complaint more seriously.

[zodPod]

I mean, these things hurt MY ears too and I'm 30. I will frequently just dry my hands on my pants. She did a great job!

[jeena]

Some air dryers start with a motion detector and and it was impossible to get most of the kids to even enter the toilet because they were afraid that it would start the dryer accidentally. I myself was confused why their reaction was so extreme but didn't think that the noise is much louder at their height and that their ears are more sensitive to loud noise too.

Interesting that it needs a kid scientist to take this on them because adults with their height bias didn't measure at those spots.

[sneak]

I wonder how sanitary they are, considering that they are basically using a bunch of bathroom air blasted at your previously-clean hands, too.

I would hate those things even if they were silent.

[astura]

You're also breathing bathroom air though?

[tkahnoski]

My 3 year old covers his ears in any public bathroom regardless of whether anyone is even in there.

Hand dryers are one item but there are some toilets that are also excessively loud as well.

[bifrost]

I honestly hate hand dryers, half the time I end up drying my hands on the sides of my pants if I'm wearing jeans... My kid hates the sound of them too so it totally makes sense that they're actually bad.

[qazpot]

I have never understood hand dryers. I mean how lazy one can be that they need a machine to blow hot air instead of wiping their hands.

[finder83]

They're not for the benefit of people who use them. They're supposedly cheaper than paper towels for the owner, and there may be some environmental benefit. I haven't seen research into either claim though.

[probwalk]

Kudos to the author!

My toddler son is always scared by the hand dryers. He refused and tried to escape from bathrooms with hand dryers.

[vasco]

Just wipe your hands on your pants after shaking them in the air for a bit.