I went to university in Arkansas, a state which boasts two of the distinguishing characteristics of the South: heat and humidity. As a member of the Harding University Marching Band, I got to spend an hour and a half every day of every week out in the sunshine practicing halftime shows in late summer, and then, as a treat, got to perform those halftime shows while wearing a heavy black wool uniform. So when it comes to heat, I know whereof I speak.
Human beings are warm-blooded and, like all warm-blooded animals, operate most effectively when their body temperature is within a rather narrow range: what we call our “normal” temperature. Traditionally this is considered to be 37 degrees C (98.6 F), although the real range of “normal” temperatures is much higher, from at least 36.4 to 37.2.
We’re called warm-blooded because we’re able to keep our body temperature within that rather narrow range. In Saskatchewan we put that ability to the test in both directions. Keeping warm is a challenge in the winter, but this time of year, keeping cool can be just as much of a problem.
It’s important to keep cool because a high body temperature can impair cell function or even damage the cells themselves. The body has built-in sensors of both warmth and coldness in its core and in the skin. When the brain gets more signals from the warmth sensors than from the cold ones, it activates the body’s primary cooling systems: flushing and sweating.
Every square centimetre of skin contains up to 70 centimetres of blood vessels. By dilating these blood vessels, the body routes more blood close to the surface, where it can radiate excess heat into the surrounding air. The skin also contains sweat glands, whose production increases when the body is overheated. Sweating itself doesn’t cool the body, but the evaporation of sweat does; every rapidly moving molecule of sweat that zips off into the air takes a little excess heat with it. This cools the skin, which in turn cools the blood flowing through the skin, which in turn cools the rest of the body. High humidity makes us uncomfortable because the high moisture content of the air prevents sweat from evaporating from our bodies, and therefore from cooling us–plus, of course, it leaves us feeling damp and sticky.
One form of cooling humans don’t use much but is seen in many animals is panting. This works exactly the same way as sweating: the evaporation of water from the animal’s nose, mouth, throat and lungs removes excess heat, cooling the blood as it passes through those regions and thereby cooling the whole body. Humans don’t pant because they have naked skin, which makes sweating very effective, but sweating doesn’t work as well when you’re covered with fur. Dogs are the champion panters: they don’t sweat at all, and therefore rely entirely on panting entirely to keep cool.
The body’s goal is to keep your temperature below 38 degrees Celsius. Above that, you risk heat exhaustion or, worse, heatstroke.
Heatstroke, or sunstroke, is a very dangerous condition that is fatal 80 percent of the time if left untreated. It occurs when the body’s temperature-regulating mechanisms are overwhelmed. Excessive sweating can deplete the body’s supply of salts, which disrupts the central nervous system. In a heatstroke victim, sweating actually stops, producing hot, dry skin and a body temperature of 41 degrees or even higher. Early symptoms are dizziness, fainting, tingling and mental confusion; eventually the victim may fall unconscious. First aid must be immediate: the goal is to bring the victim’s temperature down below at least 39 degrees. This is usually done by rubbing the victim’s skin with cold water or alcohol. A cold bath (though not an ice bath) is a good idea if available. Once the temperature reaches 39 degrees, cooling can proceed more slowly.
Heat exhaustion is a less serious condition in which a person becomes fatigued and sometimes dizzy or nauseated due to long exposure to heat. In heat exhaustion the body temperature is still normal, or even cooler, and the victim is still sweating–profusely, in fact. Heat exhaustion can sometimes cause cramps, as well.
Both heat exhaustion and heatstroke can be prevented if proper care is taken in hot weather. Avoiding exertion is the simplest solution, but sometimes that’s not an option: it’s not one we’d want, say, Tom Burgess to exercise during a hot game at Taylor Field. Probably the second most effective preventative measure is to maintain a proper intake of fluids. A person who has become acclimatized to hot temperatures (something which can take a couple of weeks of daily exposure to hot weather, so we seldom have that opportunity in Saskatchewan) can sweat as much as two quarts an hour if they’re exerting themselves in the heat. It’s important to replace those fluids. Once you feel thirsty, you’re already one to two percent dehydrated, so in hot weather you should drink lots even when you don’t feel thirsty.
I know what you’re thinking, but you’re out of luck: alcohol should be avoided, as should liquids that contain caffeine. Both actually increase water loss.
Eating regular meals can also help; food contains water, beverages usually accompany a meal, and foods also increase the concentration of salts and sugars in the blood, which activates thirst and makes you feel more like drinking the liquid you need.
Clothes in hot weather should be loose fitting (for ventilation). Cotton is an ideal material because it breathes and retains moisture. Light-colored clothes are best because they reflect heat. (Black wool band uniforms are not a good choice. Trust me on this.)
Because of the high concentration of blood vessels in the scalp, keeping the head cool helps keep the whole body cool, so a hat helps. It helps even more if you keep it wet.
While we do have our share of hot days in Saskatchewan–Yellow Grass and Midale jointly hold the record for Canada’s hottest day, 114 degrees Fahrenheit (they didn’t use Celsius back in 1937)–“at least it’s a dry heat.” And it’s usually short-lived. But that’s no reason to treat it cavalierly. Just one hot day is enough to make you sick, if you don’t take care of yourself.
So enjoy the summer, but be careful–and be thankful you’re not in Arkansas.
I know I am!
