Hey, smart people.

Joe, here.

One of the most effective ways that you can prevent yourself from becoming a statistic and catching some nasty germ, whether it's during a global pandemic like COVID-19 or just every other normal day of your life, is something that people have been trying to get you to do since you were like, two-- wash your hands with good old soap and do it the right way.

That's it.

But most people don't understand what's really happening when you wash your hands with soap and water.

So today, while I'm cooped up here at home social distancing and all that, I'm going to teach you the real science of why soap is so good at killing germs like viruses and bacteria and how it compares with stuff like this.

[SQUIRT] [MUSIC PLAYING] So what is soap?

For something to dissolve into something else, they have to share certain chemical properties.

Stuff that has any electric charge or polarity will only dissolve in a solvent or liquid that also has polarity.

This is why salt dissolves in water, but oil doesn't.

Oily stuff doesn't have much charge or polarity, so it would rather just stick to other oily stuff.

And a lot of dirt and grime is pretty oily.

So water just runs right off of it.

The reason that soap is so good at cleaning your dishes and your hair and everything else is because soap helps water be friends with oily things instead of enemies.

Soap is made of molecules that look like this.

You've got a charged head up here, which is hydrophilic.

That means it likes water.

And then you've got all these carbon and hydrogen bonds that are really oily.

They hate water.

They're hydrophobic.

This means soap can link up with both kinds of stuff, and make stuff that normally wouldn't dissolve in water dissolve.

MOLECULE: Hey friend.

We just want to be friends.

JOE: People accidentally figured all of this out way before we knew anything about chemistry.

The oldest soap making goes back something like 5,000 years.

Humans are pretty smart.

Except they didn't figure out the whole germ thing until a lot later.

But anyway, so that's how soap cleans your dishes and your hair and other stuff like that, by making oily stuff dissolve in water.

But what is soap doing to germs like bacteria and viruses?

Soap isn't just washing germs off.

It kills them.

[MUSIC PLAYING] Because soap destroys how cells are built.

Every cell, whether it's your cells or my cells or a bacterium, is surrounded by a membrane.

And those membranes are made of two layers.

Every molecule in those layers has one oily end and one water-loving end.

Now the oily ends sit together in the middle in a sandwich like that.

And the water-loving ends face out to the inside and outside of the cell.

Now in all of these membranes, there's no covalent bonds holding all these molecules together.

It's just water-loving stuff sticking to other water-loving stuff.

And water-hating stuff sticking to other water-hating stuff.

But soap comes in and messes all of this up.

It's like a little missile that comes in and breaks up all that oily inside membrane and tears holes in it.

And all the little proteins that are embedded in that membrane, well, it actually unwinds those proteins too so they can't do all their protein things.

It just lays waste to the germs-- rips them apart.

I mean, if you could get close enough while you're washing your hands, maybe you could hear little germs scream or something.

Just kidding.

Or am I?

And this is where we come to viruses, like the new virus that's causing COVID-19.

Viruses aren't technically cells in the traditional sense.

They're more like self-assembled nanoparticles.

They've got their genetic material on the inside, and then this spiky suit of armor made of protein.

Now some viruses do have a little oily membrane because of how they're replicated.

When soap meets a virus like SARS CO-V2, it disrupts that oily membrane.

It breaks up that little protein suit of armor.

It just lays waste and it crumbles like a house of cards.

Boom!

Goes the virus.

Dead virus.

Now you guys can debate whether or not viruses are actually alive and whether you can actually kill them down in the comments.

But-- so what you're actually doing when you wash your hands is not only breaking the bonds between the germs in your skin, you're not only removing the grinding oily stuff that germs like to stick to, you're actually destroying the very germs themselves.

And that's why washing with soap and water is so effective at keeping you healthy.

So why is washing your hands frequently so important?

Because germs can persist on different surfaces for sometimes days.

You touch that surface long after somebody who's infected has been there, you touch an exposed area, and that's how the germs get into your body.

So every once in a while, do a little germ-exploding on your hands.

All right.

So what about this stuff?

Alcohol-based hand sanitizer.

A lot of people are turning to this stuff these days.

And if it's the right percentage alcohol, over 60% or 65%, then those alcohol molecules-- well, they get in there, just like the soap molecules do.

And they get in between those membranes and they unwind the proteins.

And boom.

Dead germs.

[HIGH-PITCHED SCREAMS] [SNIFFS] Mm, smells like it's working.

Alcohol-based hand sanitizers work really well if you don't have access to soap and water.

They're super convenient.

But this stuff does not work better than soap and water.

In fact, sometimes it can work worse.

You tend to put it on really quickly.

And people don't necessarily scrub all the surfaces.

That smell makes you think that something medicinal is happening.

It's almost like a chemical placebo effect.

And you don't tend to get as much scrubbing action, which physically dislodges those germs from your skin.

So again, it's good if you have no other option.

But make sure you're using it correctly.

And make sure you're using the right stuff.

Check on the back and check that alcohol percentage.

I think we need to start from scratch, go back to the very beginning, and just learn how to wash our hands again.

That's right, we're going back to kindergarten.

And to help me out today, I brought something really special.

I got some fake germs.

This stuff is really oily.

It sticks your hands the same way that germs do.

And more importantly, it fluoresces under ultraviolet light.

So when I put this on my hands, try to wash it off, we're going to literally be able to see how good a job I did.

All right, you dirty dogs.

I'm going to teach you how to become a real hand-washing pro.

OK?

Let's start with our fake germs here.

I'm going to slather myself up in this.

That is coronavirus or your favorite germ of choice.

Mm, germy.

All right.

Let's go see what I look like.

Oh, yeah.

This stuff's everywhere.

All on front and back.

You can see I even got it under my nails.

And this stuff is pretty greasy, like real germs.

I'm interested to see what it actually takes to get this stuff off.

You go to the bathroom and give, like, a quick little rinse of water.

Guys, I know you do this because I've seen you do this.

What?

Have I ever done this?

This is not about me right now.

Let's stick to the issue at hand.

I'm going to rinse these under water to show you how well this doesn't work.

[WATER RUNNING] All right.

You shake it off like do.

And then you go about your business.

And then you will towel off.

And you're out of there.

Let's go see.

That did not work.

There's still germs everywhere.

This was as good as doing nothing.

You might have just walked right out of the bathroom.

Plain old water doesn't work, guys.

Now I'm going to wash my hands like I do on, like, a plain old normal day, when I don't have a bunch of people watching me on a YouTube video; you're in a rush; you got to get back to class; you suds them up real quick.

Then you got to get back to Netflix, since you paused or something, and then you go.

Well, let's see how well that works.

[WATER RUNNING] [HANDS RUBBING TOGETHER] [HUMMING] Good enough, right?

Let's go see how we did.

All right.

That didn't go well.

It got some of the germs off, but especially in those hard to reach places in between the fingers, under the fingernails, backs of the hands.

My hands are still covered in germs, just ready to wipe onto my face or something else and pass that on.

Now I'm going to show you how to wash your hands the way we should all do it every time.

And get rid of all the germs.

First, you going to wet your hands with clean running water.

Warm or cold, doesn't matter.

And then turn off the sink.

Nobody likes a water waster, OK?

And then you're going to lather up with your soap of choice and get it in there, you know?

And this is where technique comes in, because your hands are full of nooks and crannies where germs can hide, places you might not think to wash.

So you need to know how to do it.

My favorite way is a song.

Don't feel weird about it.

We all sing in the shower, anyway.

The sink is only a few steps away.

Somebody gives you a funny look, just say, "Hey, man.

Look how clean I am."

I saw this song on Instagram.

I love it.

It's by an artist named Lucy Nicely.

I'm going to put a link down in the description.

It's great.

She's great.

Here's how it goes.

(SINGING) Soap and water.

Soap and water.

Start the fire.

Start the fire.

I could use a back rub.

I could use a back rub.

I'm so tired.

I'm so tired.

Time to milk the cow now.

Time to milk the cow now.

One through five.

One through five.

One through five.

We're going to keep going on that.

One through five.

Scratch the puppy.

Scratch the puppy.

It's so fun.

It's so fun.

Now you really oughta dive into the water.

Now we're done.

Now we're done.

All right.

Let's go see how we did.

As you can see, this worked a lot better.

Almost all the germs are gone from my hands.

But even after all of that, you can see I still missed a couple spots.

Just goes to show you how difficult it is to get all the germs off your hands.

You really got to concentrate while you wash.

So what soap should you use?

Well, it doesn't matter.

Soap is soap.

We all love to read the labels, right?

We do it in the shower.

We do it on the toilet.

I mean, get in there.

Read some soap labels.

I guarantee you just about on every single one of them, the second or third ingredient is just going to be soap.

You're going to see stuff like sodium lauryl sulfate, sodium laureth sulfate-- big, long, complicated chemical name.

Pop them into Google; you're going to see soap is everywhere.

Check the back of your soaps every once in a while, and you're going to start to see a lot of the same stuff is in everything, whether it's a $3 bottle of dish detergent or $150 bottle of shampoo.

Most of this difference is just perfume and marketing.

I mean, I've got the hand soap here.

I've got, like, dish soap.

You could use laundry detergent if you really had to.

All of this stuff is going to effectively break open those germs and lay waste.

Liquid or bar soap?

It doesn't really matter.

Just make sure you work up a good lather and use the right method.

And germs don't live on bar soap, despite much you might have heard in the past.

A lot of people are using foam soap these days.

This stuff's great.

Use that.

You might have to scrub a little bit longer because that foam works a little bit differently than a liquid soap, but it's great.

Same germ-killing stuff.

Now if soap kills and explodes cells, then why doesn't hand-washing leave me looking like a skeleton?

Well, that's because the outer layer of your skin is mostly dead cells anyway.

Now if you wash too much, you could irritate your skin.

So, you know, exercise moderation, but stay clean.

Air hand dryers or towels?

What should you use to dry your hands?

Well, both are fine.

I'm more of a towel guy.

Because when I see one of those air hand dryers, I'm like, maybe that guy didn't wash his hands well enough And that's spraying aerosolized germs all over the room, kind of defeats the process.

Are there cases when good old soap isn't enough?

Now in normal everyday life, good old soap is going to do the job almost all the time.

There are some special cases, like, if you're a surgeon and you're going to, like, literally have your hands inside of somebody else.

Or if you're around really nasty germs like Clostridium difficile or nasty bacteria like that, then you might want to use a product that has some additional anti-microbial stuff.

But again, regular everyday life, you and me going about our business, good old soap will do the job.

I just thought of another cool experiment we could do show you how soap is so good at busting open cells.

And I'm going to extract my own DNA right here in the kitchen.

This is like, a teaspoon of saltwater.

I'm going to swirl this around in my mouth for 30 seconds.

Hold on.

[SWISHING] OK.

I bet that was fun to watch.

I'm going to spit in this cup.

OK. Now I'm going to take a teaspoon of that stuff-- that's gross-- pop it in a test tube, I've got a teaspoon of soap and water mixed up.

We're going to add that to my cells, swirl them up.

All right.

We're going to let this go for a minute.

They're busting open right now.

You just-- you can't see it.

It's microscopic.

Broken open cells, look at that.

That's awesome.

But we're not done yet.

I got to go get some isopropyl alcohol.

Hold on.

OK.

This is cold isopropyl alcohol.

You have in your medicine cabinet.

I've had this in the freezer, so it's super cold.

We're going to take three tablespoon of this stuff.

We're going to pour this slowly down the side.

Watch what happens.

So what the alcohol is doing is helping the DNA precipitate out of the solution.

It's actually making it not soluble in water.

So the cells burst open, they let everything out.

This alcohol is just-- [WHOOSH] We're able to pull that DNA right out of there.

See the strands floating around in there?

That's my DNA.

Ah!

Awesome.

All of this only worked because I was able to bust open my cells with just common soap like I got sitting next to the sink here.

That's because soap is so good at exploding cells.

So there you go.

In the fight against germs like coronavirus, one of the most effective germ-killing tools on earth is right at our fingertips.

And it's cheap.

And to get it to work, you just add water and you scrub.

Stay clean and stay curious.

Hey, guys, I hope you enjoyed this special view from my kitchen.

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