way gonna get this thing started. We're gonna do this. Yeah. Yeah, we're gonna do it. You know why we're gonna do it? Because this this this this viscous, viscous a car overheats because of its loss of ability to exchange heat. That's Tom Langfitt, owner of automotive Instincts and a master mechanic. Combustion process generates heat uses coolant flowing through the motor exchanges the heat via the radiator in the front of the car. So when it loses its ability to exchange the heat, it continues to get hotter and hotter and hotter until it eventually breaks down or has severe catastrophic failure. I'm Dr Mel Herbert. I'm Dr Jess Mason. And I'm Oh, I'm just Dave Mason.

Any clues on what we're talking about a day from now? Intro Scratch, scratch. I'm going with overheating hotness, bringing on the hot, hot, hot You gotta Dave, in this episode of this won't

hurt a bit. We are going to cover the science and physiology of what happens to our bodies in the extreme

heat. That sounds cool. Cool. Yeah, but I put the school doesn't sound hot. Mrs. Hotton's this might you hot Dave? Does this make

you heart Okay, So, Dave, to better illustrate this, we're gonna need you to imagine that you are in the hottest place on Earth, which is Death Valley.

Can you picture that? Yes. I actually have been to Death Valley before. Was that a retail hawkbill? I think Bill just played a red tailed hawk. I don't even know if there are red tailed hawks in Death Valley. Are there? Yes, Dave, there are actually red tailed hawks in Death Valley. I looked it up, and that sound is often mistaken for a bald eagle. Which actually sounds like this. Me? Another interesting fact. What red tailed hawks excuse to

do with their feathers. Death Valley is actually the site of the hottest recorded ambient temperature in the world, which was, Ah, 134 degrees Fahrenheit. That's 56 Celsius on July 10th 1913 at a place fittingly called Furnace Creek Ranch. It is the lowest, driest and hottest place in North America. What's that

sound? Well, it's 12 degrees in Cleveland right now, So to inspire my imagination, I'm turning on the space heater. I was trained in method acting. Summers in Death Valley get dangerously hooked, making it the perfect setting to talk about surviving extreme heat. And speaking of that, have you heard of the story of William Martin? Love fever? No hope. Should I picture him, too? Is he here with me? Like, what should he be wearing?

Shorts? Dave, Dave, you truly have a colorful imagination. This story takes place in a different desert in the remote southern Utah desert. In fact, there are few shrubs, visits and very little else. Dave, can you picture that? Yes, I'm there. In my mind, I see one shrub off to my right. It's very clear. Temperatures average over 100 degrees or about 38 degrees Celsius during a day in the summer,

and rainfall is essentially zero. Despite these inhospitable conditions. William Martin a fever and, yes, that's right. He has favoring his name, wandered into the desert and was lost and alone for three perilous weeks without water without food. And yet somehow he survived. A 28 year old autistic man was lost for three weeks in the deserts of southern Utah until rescuers found him barely alive. Well goes like this. It's June 2012 and William's father wired him some cash to the closest town page, Arizona. Unfortunately, it was about 90 miles away, and without transportation, Martin's plan was to get a boat ride that would take him to the Escalante River and then continue south toe like pale.

And there he would arrive in the City of Page. But the decision would prove to be on Aaron judgment, one that would send him on a three week trick into Hill. Rescuers estimate he'd hiked nearly 50 miles. His dog left him and he shed equipment is he wandered down the river, and as he walks through the desert, he tried to survive on plants and frogs and roots and, thankfully, was able to drink occasionally from the Escalante River. Martin's family, of course, began to worry about him and reported him missing. The sheriff's department began a search and rescue mission, but Martin was gone for three weeks. He was lost and alone in this unrelenting desert. Search and rescue helicopters continue to look for him,

but Hope was studying adrenal day after day. But then, by luck and good training, a helicopter spotted him miles from leg pal. Unbelievable that we found him at all on that he was alive. He didn't have much strength left in him. He had been spending his days laying in the river and his knights laying on the bank, so I kept him from getting overly dehydrated. He was taken to a local area hospital for further medical kit, where, by all reports, he actually did well. He was severely emaciated, but other than that, he was in much better shape than we would have predicted. Wow, There are so many questions about how Martin could have survived for so long in a desert. Starting with how did he not

overheat? He had the benefit of being in a dry desert.

What is opposed to a wet

desert? Well, I wouldn't call it a wet desert, but there are places that are both hot and humid. Both of these factor into a single measurement called heat Index. He index is a measure of how hot it really feels outside, taking into account both air temperature and relative humidity.

That's meteorologist Kristen

Chapel. So on a day where the air temperature is, say, 88 degrees, if the relative humidity is upwards of 80% it doesn't actually feel like it's 88 degrees outside, it would feel more like it's 106 degrees outside.

When we lived in California, the summers were really dry. But in Ohio, the summer's air really humid. You're always sweating, and you can't cool off. Even when you get out of the shower, it's like you can't

dry off. When it's

dry and hot, you sweat, and that sweat cools you off by evaporation and takes the heat from the skin into the water. And off it goes. When it's humid, you still sweat. But you can't evaporate off a cz much because you know there's already moisture in the air already, So you're sweet doesn't cool you down as much. That's why heat Index takes into account. The temperature and the humidity is a bit a measure of how hard it is for an actual human being, but there's actually an even better measure of how hot it really is. But we're gonna get back to that one

in a minute. It was once thought that the highest heat index possible was, Ah, 160. But on july 8th, 2003 in Dhahran, Saudi Arabia, ah heat index of ah 178 degrees. That's 81 Celsius was attained the temperature

and Iran was 108 degrees Fahrenheit. That's 42 degrees Celsius, and it was humid. We're talking really human. On a day like that, a person can actually die within hours.

The National Weather Service considers that a dangerous number when it starts to reach 100 degrees. At that point, the issue a heat advisory if the heat index reaches 105 degrees or greater and it's expected to last for two consecutive days or more than the issue in excessive heat warning, there's

another measure of how hard it is that's endorsed by the American College of Sports Medicine. It gives us a cut off of when it's too hot to exercise its cold and wait for it. Wet bulb. Globe temperature index

just rolls

off the tongue. Okay, what mailed? Stick with me on this. I'll speak slowly so you can understand. Okay, it's wet. Bobo bh Globe temperature. Okay, Got it. Never heard of it. Well, let's go to Al McKenzie. Medicine and Sports Medicine specialist Dr Met bid for an explanation. So basically, what it is is a measure of heat stress in direct sunlight, and it takes a number of important issues or factors into account, including

ambient temperature, humidity, wind speed, son angle, cloud cover, basically solar radiation all packed into one measurement. And it's something that you can look up. The basic guidelines, and this is mainly sent down from a CSM, which is American College of Sports medicine, is that anything over a reading of 82 is not compatible with competition for folks that air training for something like a marathon. And if you're in shape, if you towards the end of your training and you're feeling pretty good and you're happy about yourself, then the threshold goes up a little bit more, even to 90 and 32. So the wet bulb Globe index is one number that takes many different factors into account, and you can easily look it up online.

So if you're a parent or a youth sports coach, the cutoff is 82 degrees Fahrenheit or 28 degrees Celsius, and that's according to the American College of Sports Medicine. Anything over that you shouldn't be out there exercising. It sounds like a pretty important way to keep temperature. I can't believe I've never heard of this before. Most people probably haven't. And that's why it's a good thing to listen to exceptional medical science podcasts with extremely handsome hosts. Plug No shame. Okay, now we have three measurements of how hot it is. Temperature heat index, which also accounts for humidity and wet bulb globe temperature, which also accounts for wind and solar radiation. So Death Valley gets really hot. Diran got even harder by heat index. Do you know where the hottest place on earth actually is doing?

Okay, it's Dhahran, and I'm sorry. Trick question. It's your car car. Okay, so let's just recap. I'm in my car in Death Valley and William Martin A fever is my passenger. Thank you, Bill. And a red tailed hawk is flying above. Okay, I'm here in my mind. Now tell me why a car could become the hottest place on earth, Mel. Well, David, because of the greenhouse effect, it's just like global warming. But on a smaller and much more intense

level, the sun emits shortwave radiation which comes through the windows. And can he objects in the car, such as the dashboard to temperatures in excess of 180 degrees. Those objects that in turn, will heat the surrounding air in the car and admit long wave radiation, which is less efficient at escaping the car. If

you're trapped in a car on a hot day, even on a moderately hot day with the windows closed, you'll absorb way more heat into that car than that car can release back into the atmosphere so you can quickly get over 130 degrees inside the car. At those temperatures, a person can die really quickly within hours, and it's even more dangerous for small

Children. Yes, and sadly, there are 20 to 30 deaths of small Children every year from hypothermia and

cars. The car unlocked, windows up, not running. Waffle House workers did what they could, but neither they nor E. M s could revive the infant pronounced dead at the scene. A P D has been questioning the young adult who came running out to the car. The man in care of the child, they say, is extremely distraught. It's been a difficult interrogation.

Children are much more susceptible than adults because they can't open the car door. They also have a larger surface area to absorb heat and less ability to sweat so they absorb more radiant heat, and they can't cool themselves down as efficiently.

And, it turns out even cracking the window doesn't help very much, either.

And so, even

on a cool day, say, in the seventies, you're gonna be careful because the internal temperature of a car can still get dangerously high. It's really just no safe amount of time to leave a small child in a car, regardless of the temperature outside. Okay, this is all sounding pretty depressing. And if this is my imaginary world, there's no global warming and no kids trapped in cars, Okay, just me and Martin A fever. Okay, so you're sitting in a car and your body starts to heat up. You become really susceptible to heat illness, Okay, And what is heat illness?

To me, this just sounds like like I'm sick of the heat. Well, it's a little bit more than that. Heat illnesses this general term. It's like saying my car overheated. That doesn't really tell you exactly what's going wrong. Okay, so then what are the specific types of heat illness? All right, so Let's just name a few. There's heat cramps. Hey, fainting. Or we would call it sink a P heat exhaustion and then the worst form heat stroke. Can you have all of these things at once?

You can have one of these things, or you pretty much can have all of them. But it's really a progression from the not so bad things like heat cramps all the way up to the worst thing. Hate stroke If your body temperature is rising, isn't that what's called a fever?

Actually, that's an important distinction. A fever like when you get sick, that's your brain telling your body to heat up. It's a function of your immune system and your hypothalamus in your brain. In medicine, we use the temperature cut off of AH, 100.4 Fahrenheit. That's 38 Celsius. And that's because, frankly, we need to have some specific number in mind to define fever and study it. Does that make sense? Yeah, it does. So a fever is caused by the hypothalamus in your brain, raising your body temperature in response to an

illness like a

thermostat. Yes, that's why we call it Thermo Regulation, because it's exactly like a thermostat. In fact, the hypothalamus is so good it can detect temperature changes of 0.1 degrees Fahrenheit.

Okay, so this must be the explanation for why women say they're always cold, right? Because they're overly sensitive. David. No, that didn't come out right. No, no, wait, Hold on. No, I mean your hypothalamus is overly sensitive. Not not that that's a bad thing,

that, you know. Uh, I'm just gonna move on from that comment. Mel, as doctors, we know that there's really only one treatment for a fever.

I'm sorry, but what was I supposed to be doing right

there? It's more cow bell. That line. I got a fever. The only prescription is more cab watching Saturday night Live. Now, on the other hand, there's hypothermia. Okay. Hypothermia is the environment. Raising your body temperature just like a car. Your body has mechanisms. Try to cool itself down like sweating and thirst. But when your body can't keep up, it starts to fail like a car overheating. This is heat, illness and hypothermia.

Take me through the steps from heat, illness to death. How does that

happen? So once you become hyper thermic, you can get a fast pulse, low blood pressure, extreme weakness, dizziness, vomiting and diarrhea. And this can progress to heat stroke. And just like the word stroke implies, there are neurological problems like confusion and sometimes seizures, and this tends to occur with body temperatures over 100 and four degrees Fahrenheit.

Okay, and what happens if you still can't cool down? If temperatures david this level not quickly reduced, then irreversible damage can occur. You see, your body is full of enzymes, and these enzymes are designed to work its specific temperature ranges. If your body gets too hot, these enzymes just don't work. Cells die without functioning cells. Your lungs start to fill with fluid. Your kidneys get blocked, your nerves misfire, making you confused and maybe even going into a coma. So if you don't call this person down fast at that level, this person can die from heat stroke,

and some populations are at higher risk for heat, illness and others. You should be looking out for those who were very young and very old to make sure that they're taking the proper precautions to stay cool.

But having said that, even young people on healthy people can get hate illness sometimes because they are young and healthy and they don't know the dangers. For some reason, they're people that believe that exercising on really hot days to get a really good sweat going is somehow intrinsically healthy. Well, I can tell you it's not. It's potentially lethal. I'll never forget standing over the body of a 22 year old u. C L A student. This was about 10 more than that, probably 20 years ago. It was like the hottest day of the summer, and this guy had decided to run up and down the hills of campus with a sweater on, presumably to get one of those good sweets going. He was an athlete. He was a superstar in fantastic condition. But he ran and ran until he got confused and collapsed,

and they brought him to the ear where I was one of the docks looking after him. His initial temperature in the men's department was 108 degrees, and despite rapid cooling with water and ice and doing everything we possibly could, his temperature actually increased to 110 and an hour later he arrested and died I gotta tell you, I was shocked by that, and it still makes me said today. This young kid literally ran himself to death on a hot day. It's not like this is the only case of this every year in the U. S. And across the world, young fit super athletes die exercising on hot days because they and their coaches don't recognize just how dangerous this is, even if you're in great shape.

This is a tragic story, and this athlete was trying to sweat trying to make his body hot. This is totally different from athletes who gradually trained in the heat to build up a tolerance. Let's bring another expert into the conversation to answer this question.

Okay, Should I be imagining this, or are you actually going to talk to somebody because I'm running out of room in my car? Well, there's a number of things that happen with people when they adapt or get used to the heat. It's Michael Bergeron, PhD exercise physiologist with over three decades of helping athletes understand an adept to exercise in the heat. He's also president and CEO of Youth sports of the America's number one. It takes Ah, very amount of time, depending on how used to the heat he or she is before being exposed. If you're an athlete, training in the cold and then go to a hot climate, it can take about two weeks before you fully adapt, and you have to do it in a slow and safe way. Generally, what happens to the body is a number of things one related to your cardiovascular system, and that results in an increase in blood or plasma volume, particularly so your body retains more

fluid. So more blood volume is like having MME. Orgasm the tank. It helps your heart function more efficiently.

The other side of it is that your body, because it retains religion, also retains electrolytes, primarily sodium and chloride, or retain salt that helps the body hold onto the fluid. But there's also an increase in the sensitivity and the output of your sweat glands, so you're regulating temperature better. So what he's saying is that your body gets better at retaining salt so you hold on to more fluid

exactly, and you also become better at sweating.

But also, of course, what that means is that you need to make sure that you're keeping up with your fluids and your electrolytes because you're losing a lot. Okay, but what do you do with a patient in the E. R who has heat illness like the C L. A student that Mel saw

So stuff that we do quickly, we would undress them. We would rapidly

cool them. That's Claire Ricky. She's in emergency medicine, physician and fellow in emergency medicine at the Kick School of Medicine,

and this could mean anything from packing them with ice in their axe. Illa

I'm sorry, What's X illa? Sounds like a General Roman

general. Excellent means armpit. But it was named after the Roman general Excellent

Right, who was famous for running into battle with his arms

up in the no, it's completely made up. So in their armpits, in their groin, in their neck, you could do I soaked towels. Anything really cold or often will do something called evaporative cooling on our own, where we spray them with tepid water, which is the fancy word for not too hot, not too cold, but somewhere right in the middle and with the tepid water. They don't get tons of goose bumps which, when you think about it, your body gets goose bumps to retain heat. Is

that the same idea as when you're standing in line at the amusement park and their spring misted water

on everybody? Yes, exactly.

And what about the idea of just sort of giving them a Tylenol, treating it like a normal

fever? Actually, in this case, Tylenol is not the answer, because heat stroke is a failure of those regulatory systems of your body. So this heat is not from the center that says, Oh, I'm sick. I have a fever. Give Tylenol. It actually won't respond to Tylenol. It'll so we don't actually recommend using it.

Okay, and what is the hottest a person can get and still survive?

That's a great question, but it doesn't have a perfect answer. A person might be able to tolerate a temperature of, say, 100 and six degrees fair knight for maybe 45 minutes or up to eight hours, depending on your state of health going into the situation. But an extremely hot internal temperature say, 120 degrees Fahrenheit. Well, that would destroy your cells and kill you in less than five minutes.

Oh, so 120 degrees is the melting point of the human body. Pretty much okay. Today we talked about all these things that might make you more risk for getting heat illness. Whether you're very young, with your very old with you're in a car, whether there's lots of humidity. But another really important factor that can determine whether you get sick or not when it's really hot is how hydrated, Youa, how much fluid is in your body? Okay. And then how long can a person survive without water?

As you can imagine, this depends on a lot of factors. That's Dr Alison Richard, an emergency medicine physician giving a lecture on surviving in the heat. So number one, what is your condition? Going into situation? Are you doing? Oh, Heil To to climb. Have you just been drinking beers with your feet up? Are you in a cool, temperate, humid rainforest? Or are you in the dry Sahara desert? So, experts, I think that you can survive actually up to 10 days if you're an ideal situations without

any fluid at all. All right, well, let's make this in a non ideal situation, okay? I've run out of water. Martin Love Fever doesn't have any water on him, and I'll take one for the team here. I'll ask the question. That's on everybody's mind. The big elephant in the room. Can I drink my own pee? I'll do it if I have to. I am in

survival mode. Well, I wasn't thinking that, Mel, were you thinking that,

um, to be honest, Of course he waas. Of course, Ken. I drink blood. P is a serious question.

So it turns out that the Army puts urine on the do not drink list. But perhaps the answer is just a little more complicated. So why does the Army advise against drinking urine? It's proposed that because of its solidity drinking, it will actually make you more dehydrate than if you drink nothing at all. A common misconception about urine is that it's gross and full of bacteria. Well, I can't argue that it isn't gross, but it's not full of bacteria. The reality is that urine is sterile. If you're in has bacteria, we call that a urinary tract infection, and we usually give you antibiotics so healthy urine doesn't have any bacteria in it at all. at least until the point where it passes through the tip of the urethra streaming across your skin, where you naturally have some skin flora that just jump on

for the ride. Okay, so what is actually in urine?

Then there's nitrogenous wastes and some little bits of hormones, some electrolytes and it's mostly water. But most of these toxins quote unquote in the urine won't hurt you if you re in just them over a period of days. Bottom line is that urine is somewhat salty, and the scientific word for how much salt or sol you is in a liquid is Oz morality. So if you eat or drink something that's really salty, it pulls water out of yourselves. Basically, it drives you out. As you get more and more dehydrated, your urine gets saltier and darker. This is your kidneys. Physiology at work. When you're dehydrated, your kidneys pull water from the forming urine back into your body. Since there's less pure water in the urine, the salt concentration is higher and the appearance is also darker,

so if you're well hydrated, your urine is clear to light yellow, like lemonade. But as you start getting dehydrated, your urine gets darker, more like iced tea. Just how much salt is in urine. So if you're really well hydrated, extra would be far less than that of drinking Gatorade. But if you've gone without fluids for several days, the levels approach

that of seawater and probably not beneficial to drink. And what does Dr Richard say about

drinking your own? I would say, if you're really well hydrated going into the inn, you're trapped. State, I would say, Save your first urine or two and drink it as a last ditch effort. But beyond that, it's anybody's

guess. Did you hear that, Dave? Save your next to pee pees. You might be to use them. Okay, I'm doing it. Once I finish this bottle water, I'm going to pee back

into it. Please, just get through one episode of this show without you guys being

Now. This is perfectly fine. This is science. This is science. Just the science of Were we drinking? Yeah. And I did say I was gonna pee back into the bottle. I didn't say I was gonna drink it. Gross. Maybe. Right, Dave, it's time to wrap it up Here. It's time to come back from your imaginary dessert. No way! No way. Cleveland is 12 degrees right now.

I'm going to stay out here in Death Valley, California, me and Martin. We're gonna go get some tacos and you're all welcome to come. Come on. What is that? Is that the car overheating? Bill, What are you doing? Thanks, Bill. Thanks for listening, everybody. Thanks to our produces CC Herbert and Bill Connor. Sound design was by Bill Connor Music this week by Matt Engels and Evil J and ST Cecilia. I'm Dr Mills.

I'm Dr Jess Mason. And also, thanks to our experts Kristen Chapel, Dr Claire Ref Key to talk to Matt Bid. Dr Ellison, Richard and Michael Berger. And I'm Dave Mason with Martin a fever in a broken down car in the middle, the desert surrounded by red tailed hawks and maybe a coyote. At least they're not vultures. This one hurt a bit. Is a production of fool Abou incorporated information you here on this phone ahead of it should not be taken as actual medical of us. You have actual medical questions about actual medical things. You should see an actual medical practitioner even though we are. Actually, doctors were not your actual doctor. So be sensible and keep it real. And this this'll finish this viscous.