This time, though, we're diving into the science related to one of our favorite summer activities.

Swimming.

Speaking of diving into things, if you're a water lover, you've probably had the unfortunate experience of jumping into a pool or lake and getting water up your nose.

Which, of course, hurts.

Ah, lot.

That's weird because our nasal passages are wet all the time and some people even clean them out with water using a neti pot.

So why does getting water up your nose hurts so much?

I'll pass it over to Hank to explain you ever done cannonball into a swimming pool or a pond and accidentally like shot like water all up in your brain for your nose?

Yeah, not a fan.

And yet neti pots, those teapot looking things that people used to squirt water into their noses when they're feeling stuffy.

They're like soothing and relatively painless.

Turns out the difference has to do with the conditions inside your nasal cavities.

See the inside of your nose, as you may have noticed, is full of nerve endings and not to get too up close and personal here.

But it's also pretty warm up there and kind of salty, with assault concentration of about 0.9% when you start up fresh cold swimming pool water.

It's a shock to your system because it's just so different from the natural environment inside your nose.

Hold temperature could even make you feel like you're having a brain freeze, probably because it's making the blood vessels inside of your nose constrict.

And since the freshwater doesn't match up with your internal salt concentration, there's an uncomfortable feeling as they try to equalize and the water flows into your cells.

Scene while your nasal membranes respond to the irritation by secrete ing a bunch of mucus, which is why your nose immediately starts running Neti pots, which flush out your Sinuses to remove allergens and thin out mucous.

Get around this by using warm, salty water that matches your internal environment.

But even though neti pots and accidental cannonball snorts feel totally different, they can both put you at risk for deadly infections, so it's very rare.

A snoot full of pond water or an improperly cleans neti pot just might expose you to brain eating amoebas called Naegleria fowleri.

Again, this is really rare.

There are only three or four cases in the U.

S each year, but it's a water dwelling parasite that, if snort it up your nose congee, get into your brain and start destroying tissue.

I'm not saying you got to give up cannonballs, but maybe just hold your nose through the thing that everybody does.

You'll get around the pain and the risk of a brain eating infection at the same time.

If you can avoid getting water up your nose, spending hours upon hours in a cool swimming pool is pretty much the best thing on a sweltering summer day.

If you do that, though, you'll probably notice yourself getting a bit prune e after awhile.

Why does their skin do that?

Well, let me explain whether you're swimming or washing the dishes or just taking a nice, long, well deserved bath.

If you're immersed in water for longer than 10 minutes.

Chances are your fingers and toes will emerge looking like raisins.

So what's up with the wrinkle digits?

For years, scientists thought the phenomenon was the result of some type of osmosis caused by water passing into the dry outer layer of skin.

The influx of water, the thinking went, would expand the skin surface area, but not the tissue below it, so the skin would bunch up and wrinkle.

But in 1935 a pair of doctors noticed that this effect didn't happen in their patients with nerve damage.

One patient, for example, was a boy who had lost feeling in three of his fingers.

The researchers found that in his hand got wet.

The fingers that could feel wrinkled is normal, but the ones that were numb remained smooth.

It turned out that the pretty digits weren't caused by just the passive flow of water through the skin.

It was an active response of the nervous system to prolonged moisture.

The nervous system causes the wrinkling by constricting the blood vessels below the skin, which causes the upper layers of skin to pucker.

Since the phenomenon is caused by an involuntary nerve response.

Some biologists have thought that it must have some evolutionary function, but what possible purpose could it serve?

One recent theory suggests that wrinkly skin may have given our ancestors a better grip, while working and wet conditions like gathering food from a stream or damp vegetation may have also given us better footing while walking across slippery landscapes in the rain.

In a 2013 study, evolutionary biologists tested this theory by asking subjects with either wrinkly or non wrinkly fingers to pick up a variety of wet and dry objects like marbles.

They found that the subjects with wrinkly digits picked up the wet objects 12% faster than their counterparts, but there was no difference when it came to picking up dry objects.

The wrinkles apparently helped channel the water away, much like the treads on your car's tires.

But then this raises the question.

If wrinkly skin gives us a better grip, then why isn't our skin wrinkly all of the time?

Well, maybe because shriveled fingers and toes are less sensitive, which is no advantage at all.

Raise any fingers isn't the only thing pool water can do to your body if you're swimming around for a long time in a pool you might find the your eyes get all red and kind of burn.

You might think that's just a reaction to the chlorine, but it's not.

Here's Hank with more.

Maybe you've had this experience.

After a long day at the pool, your eyes start stinging a little.

They might even turn all red, a burning, itchy, bloodshot mess.

I am.

I think that's the price you pay for swimming without goggles and that your eyes air just sensitive to chlorine in the water.

The real answer is a lot more disgusting.

Apologies in advance.

The stinging readiness actually means the water you've been in for the past hour includes a fair amount of urine, sweat or even poop.

Yep, your eyes are actually doing you a sort of favor and screaming out in their blood shot pain that you've been in water that's less than sanitary.

To be fair, chlorine is still involved.

The rial offenders here, our class of chemicals called chloramine sze, which form when chlorine reacts with the nitrogen rich ammonia or similar compounds in those bodily fluids, See and sweat, for example, both contain Yuria molecule with two ammonia like parts.

When Yuria comes in contact with chlorine, it swaps out its hydrogen is for chlorine and voila!

Chloramine is born at chloramine is what actually irritates your eyes, not the cleaning stuff that was put in the pool originally.

So how do you know whether you should risk jumping into the water?

Go with your nose.

It turns out that the chlorine odor you associate with pools isn't actually chlorine.

That's also chloramine.

And not only is the smell a sign that there's a lot of bodily fluid in the pool, but because all that chlorine is bound a nitrogen, it means that there's probably not that much free chlorine left to do what it's meant to do.

Disinfect because chlorine on Lee works well, ripping apart bacteria and destroying virus is when it's dissolved in water as hypo Cloris Acid.

Once it's part of a chloramine molecule, that killing power goes way down.

So if there is a strong spell to the pool, you might want to reconsider your slim.

And if you want to help, rather than hinder the red eye problem, take a quick shower before you swim in about a minute you could wash away any sweat or dirt that you might otherwise bring into the pool.

That would make Mork Laura Means, and I shouldn't have to say it, But pretty please don't pee in the pool.

Well, I bet you're not gonna be able to forget that lovely bit of information about pools anytime soon, and it gets worse because all that pee in the pool that's making your eyes read it could be downright dangerous for you.

Here's Stephan with why, If you've ever been a competitive swimmer or just spent a lot of time the pool, you might have peed in the water once or twice.

Or maybe a lot.

According to interviews, Olympic swimmers pee in the pool all the time, even though it sounds disgusting.

A lot of people say you're in a sterile plus.

Chlorine is a disinfectant.

So what's a little P between friends, right?

You might actually want to take your business to the bathroom, for one.

It turns out that P isn't all that sterile, but there's another problem to mixing your in with.

The chlorine in your pool can make chemicals that might cause respiratory and nervous system problems and urine is mostly water, but it contains a lot of junk that your body doesn't want any more, including uric acid and Yuria, both nitrogen containing molecules.

Uric acid is produced when your body breaks down molecules called pure ings, like the ones in some of your DNA bases and Yuria is made from the breakdown of protein.

And when these waste molecules mixed with chlorine in the pool that's meant to destroy bacteria and viruses, they react to form disinfection byproducts or D.

B.

P's for short, specifically, area reacts to create a type of chemical called chloramine, swapping out its hydrogen atoms for chlorine atoms.

Try chloramine, especially, is pretty reactive and can corrode the metal in and around pools.

And you might know it by its smell.

That classic chemical pool smell is caused by chloramine.

Gas is not chlorine.

A lot of people like lifeguards have reported that they get red eyes, a runny nose or a scratchy voice after being around the pool too much, which could potentially have something to do with irritation from lots of try chloramine.

Some researchers think Laura Means could cause respiratory problems in swimmers, too, since they probably breathe in a bunch more than your average pool gore.

But we'll need to do more research to really understand the health effects we've known about the connection between Yuria and Tricolor mean for a while now.

But we've pretty recently found a link between uric acid and a molecule called cyanogen chloride.

Cyanogen chloride gas doesn't have a familiar smell, but it's really bad news and can cause respiratory, cardiovascular and central nervous system problems.

It's part of a group of chemicals called cyanide, which all have a carbon atom bonded to a nitrogen in their toxins and nasty ones.

At that, these chemicals messed with how yourselves use oxygen so your cells struggled to produce energy.

And if the concentration is high enough, all kinds of things can go wrong.

In one study, published in the journal Environmental Science and Technology in 2014 researchers created synthetic urine and combined it with various concentrations of chlorine, and within an hour the uric acid created some cyanogen chloride, the amount very based on the chlorine concentration they used, but it was around 2 to 8 milligrams per leader.

Now there aren't many official guidelines about what concentration of liquid sanity and chloride is dangerous.

But some sources recommend avoiding exposure to more than 0.6 milligrams per cubic meter of the gas form, so getting 2 to 8 milligrams per liter of cyanogen chloride sounds like a huge deal.

But it's pretty unlikely you'll ever find that much in your swimming pool, because this experiment used higher concentrations of chlorine than you'd find outside of the lab.

So you probably don't need to panic if you go to a pool party every once in a while.

DBP levels might be an issue at large swim meets, where hundreds of swimmers are probably peeing in the water, especially if a lot of people are peeing in the same spot, say, at the foot of the diving board.

That area will have higher concentrations of D B p's like try chloramine or cyanogen chloride.

And researchers are trying to figure out if long term exposure to D.

B P's are related to the unusually high amounts of asthma reported among competitive swimmers, which has been documented in multiple surveys.

Now it looks like D B P's air, probably not a life or death issue in the pool, although they're not harmless either.

So getting out of the pool drying off and going inside to use the bathroom is kind of a pain.

But your lungs and probably your friends will thank you.

At this point, you might be thinking that maybe you should avoid pools altogether.

You could always swim in a lake after all, but, uh, well, Olivia has some information you might want to consider.

First, peer Sommer has ever included cooling off with a nice swim in a lake.

You might be acquainted with something called Swimmer's Itch.

She's itchy.

Red bumps appear on the exposed parts of your skin after you take a dip in a Laker pond, and they can last for a week or more.

But swimmer's itch is more than just annoying rash.

It's actually caused by parasites that burrow into your skin and then die there.

Yeah, you.

The culprits are tiny worms called schistosomiasis.

Each sisters own species specializes in a specific birder mammal host.

Some schist, a zone species target humans causing a debilitating disease called schistosomiasis.

But the ones that cause swimmer's itch aren't after you.

They're part of a different group of species whose hosts include ducks, geese, muskrats, and raccoons.

That itchy rash is what happens when one of the sisters own larva makes a mistake.

Adult parasites live in their hosts blood, and when they lay eggs, the host eventually poops them out.

With a little luck, the eggs end up in water, where they hatch into larvae that swim around in search of the aquatic snails that they need to infect.

To complete the next stage of their life cycle, the baby sister zones continue to multiply and develop inside the snail, and eventually the infected snail releases a second type of larva called sir carry into the water.

This is where swimmer Itch gets its technical name.

Cirque Aerial dermatitis.

These little guys, each less than a millimetre long, head out to look for a member of their original host species to start the cycle all over again.

You'd think it would be easy to tell the difference between a human and a muskrat or goose or whatever, but sometimes the Sir Carrie even mess up and burrow into a human swimmers skin.

It's a fatal mistake.

They can't develop there, and so they die.

And because dead baby parasites are definitely not something that's supposed to be in your body.

They trigger an allergic reaction as they break down.

That's what the itching and readiness is from because it's an allergic reaction.

Some people are more sensitive than others.

It just depends on how strongly your immune system response.

And if you're exposed to swimmers that over and over again, you can actually become more sensitive to it.

Over time, you're most likely to get swimmer's itch in fresh water, but it's possible to get it in salt water, too.

So even if the ocean you're not completely safe to keep your risk.

Small towel offer shower as soon as you get out of the water.

And don't do anything to attract birds that might host just a zones to the area.