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"After spending time in public spaces" is not on the list of situations in which we're recommended to wash our hands — but should we do it, anyway? I swabbed the surfaces I touch every day to find out just how many germs were lurking there.

If you’ve ever seen the CDC’s “when and how to wash your hands” list, you’ll have noticed that "after spending time in public spaces" isn't one of the situations in which handwashing is recommended. 

The Centers for Disease Control — and many other reputable medical organizations — only advise you to wash your hands:

  • Before eating, but also before, while, and after preparing and handling food. 
  • When we’re done using the toilet, but also after changing diapers or helping a child go potty. 
  • Before and after tending to a wound, and before and after caring for someone who’s got diarrhea or is vomiting. 
  • After cuddling up with a pet or handling another animal, and when we’re done cleaning up animal poop or dealing with pet food. 
  • When we’ve taken the trash out. 

Should we also soap up after we spend time in public? 

We may not even “clock” all the germ-ridden things we touch when we’re out and about, after all, but could we be picking up germs from the thousands of other folks whose hands have also touched the doorknobs, shopping cart handles, ATM machine touchscreens, and literally countless other surfaces we forgot we had contact with?

Some of the folks who've had their hands all over the surfaces you later touch won't have washed their hands after going to the bathroom. Then there will be the occasional person who simply hasn't gotten this important and often-repeated message and have gone out even though they're sick — sometimes even without going anywhere near a sink:

#Flu2018: take this seriously folks! Frequent hand washing for all. If you have flu, STAY HOME. Rest. Fluids. Don't share food/drinks. If you have trouble breathing, chest pain or persistent cough/fever, see your MD ASAP. #Flu #fluSeason #WomensHealth

— Donnica Moore, MD (@DrDonnica) January 27, 2018

Is your environment a pathogen party? I took some swabs to find out how gross mine is

So, I did a little experiment. I was curious to learn exactly how dirty the things I touch every day are, and how many microorganisms they harbor.

I took samples from three surfaces —  the keyboard at the laboratory where I work as a veterinary microbiologist, the handle on the bus I take every day, and the buttons on the elevator in my building. I also swabbed my hands before and after washing them, because it's the first thing I do after I get home. 

This wasn't a legitimate scientific experiment. Many of the factors weren't controlled — the surfaces I tested weren't the same, for instance — but, on the other hand, I was just playing and curious about the rough number of bacteria in my immediate environment. 

The number of bacteria was calculated using the dilution method. The initial swab contained 5ml of saline solution. I took 0.5ml of that solution and put it in 4.5ml of a saline solution, diluting it 10 times. Then, 0.5ml of that solution was mixed with 4.5ml of sterile saline solution, and so on.

First, I took samples from the whole keyboard, including all of the buttons and the spaces between. Although I work at an exceptionally microbe-conscious workplace — we always wear gloves at my lab and wash our hands constantly — and though the keyboard looked reasonably clean, there were 5.4 x 10^5 CFU (colony forming units) on the keyboard. For the math-challenged readers out there, let’s just say that’s a lot

Next, I got on the bus and headed home. I picked a random handle and took a sample from a surface about the size of my palm. Even though the buses in my city are washed every single day, it was late in the afternoon and I figured thousands of people grabbed that bar before I came anywhere near it. I expected a lot of bacteria. And I was wrong. I counted only 12 x 10^2 on those plates.

I got into my building and into the elevator, so I took samples from the buttons. I live in an old building in an equally old, and sort of poor, working-class part of town, so nobody ever cleans the elevator. That showed in my results. I took samples from six buttons, all about a centimeter in diameter, and more bacteria lurked there than on the bus handle: 25 x 10^3 CFU.

So, I got into my flat. I kind of tried to rig the next couple of results, to be honest, to prove my point, but I failed spectacularly. 

I took samples from my palm before and after I washed my hands. Unsurprisingly, a lot of bacteria grew on the "before" plate — 73 x 10^6 bacteria were isolated. But here comes the surprise. I washed my hands thoroughly, using warm water, paying special attention to the parts between my fingers, and rinsing really hard in an attempt to prove how essential handwashing is. The results were disappointing: 26 x 10^4. Which means that, even after washing my hands, there were still 260,000 bacteria on my palm!

That's when I thought about the type of soap I use. It was a regular soap that I chose because it smells nice. I never really thought about using an antibacterial soap — but I might just do so now. (Mind you, antibacterial soaps haven’t actually been proven to eliminate more germs than regular ones. I'm not calling on readers to switch to those kinds of products at all, but it is a bit scary that even our best handwashing efforts don’t completely rid our hands of germs, no?)

So, should we wash our hands after spending time in public places?

The germs you can pick up from public places should definitely be on your radar! Bacteria are, after all, literally everywhere. While most of them aren’t going to harm you, you won’t know if you’ve picked up disease-causing pathogens until it’s too late.

One fascinating London-based study from 2009, designed to measure the effects of washing your hands with regular, non-antibacterial, soap, illustrates this quite well. Twenty volunteers went out of their way to contaminate their hands to the max by arbitrarily grabbing door handles and railings in a museum — pretty much doing what everyone does anyway when visiting a typical public space.

After the volunteers finished germing-up, they were randomly assigned into different groups and told to:

  • Wash their hands with just water
  • Wash their hands with a regular non-antibacterial soap
  • Not wash their hands at all 

All handwashing was supervised. It took the volunteers an average of 12 seconds each to wash their hands with water, and 14 seconds with water and soap. Each of them repeated this procedure 24 times, adding up to 480 samples in total.

How gross did it get? Well, bacteria mostly found in feces were detected in:

  • 44 percent of volunteers who didn’t wash their hands at all
  • 23 percent of people who washed their hands with water alone
  • But only in eight percent of volunteers who washed their hands with both water and soap. 

The soap’s germ-fighting benefits were, the team found, independent of the kinds of bacteria a person came into contact with — so washing your hands after inevitably touching countless public surfaces might even save you from a very serious infection. 

Handwashing: How much is too much?

Keep in mind that your skin is itself an important protective barrier, made up of numerous layers that can become compromised if you scrub too hard, too often, or use irritating soaps. 

Your skin’s antibacterial properties peak when its pH is acidic. Just washing your hands with plain soap for two minutes, once, may increase the skin’s pH value, and it can take up to two hours to return to normal — so, overdoing your hand hygiene can be just as bad as skipping it, a problem healthcare workers everywhere will be all-too familiar with. 

So, how can you fight germs but keep your skin healthy, too?

  • Alcohol-based hand sanitizers offer immediate protection after contact with high-risk surfaces, but are also extremely drying. For regular handwashing, choosing a mild non-antimicrobial soap is just fine. 
  • Remember that washing your hands way more often than recommended doesn’t significantly reduce the number of microorganisms on your skin.
  • Choose hand hygiene products that are gentle on the skin — and switch to a new soap if you notice any reactions. 
  • To keep your skin moisturized, consider using a hand cream after you wash your hands.

Handwashing is one of the simplest and most effective ways to prevent the spread of diseases, and you may well be “punished” for slacking with an unpleasant infection. When it comes to hand hygiene, however, “more” doesn’t always mean “better”. Try to find the right balance between never washing your hands and spending hours a day with your mitts under the sink. 

While you’re at it, ask yourself when someone last cleaned that communal keyboard, doorknob, or elevator button in your immediate environment — and perhaps give them a nice disinfecting wipe.