Visit Your Local PBS Station PBS Home PBS Home Programs A-Z TV Schedules Watch Video Donate Shop PBS Search PBS


Heatstroke SidebarDeath Valley is the lowest, hottest, driest area in North America, where in the summer, temperatures commonly run above 120° Fahrenheit. It was named by an unlucky group of miners who crossed the valley in 1849, on their way to California. They barely survived. "Good-bye, Death Valley," one of the miners said as they staggered out of the desert, and the name lives on today.

Despite the foreboding name -- and the heat -- more than 1.3 million people visit every year. And each year, there are about ten heat-related fatalities.

Geologists at Racetrack Playa.One of the dangers visitors must contend with in the unforgiving climate of Death Valley is heatstroke. It occurs when the body is unable to control its temperature, and the sweating mechanism fails.

When the mercury rises, the body tries to keep its internal temperature stable. It has two main mechanisms to facilitate this. The heart pumps more blood, vessels expand to accommodate the increased flow, and excess heat is released into the environment as the blood circulates close to the surface of the skin. The body can also activate its sweat glands, and as sweat is produced and evaporates from the skin, it cools the body.

Sometimes, in extremely hot and humid conditions, people sweat so much they become dehydrated. If this happens, sweating may cease, while the body's internal temperature continues to rise. It can quickly rise to 105° Fahrenheit or higher within 10-15 minutes, and do damage to the internal organs. Warning signs of impending heatstroke may include: extremely high body temperature, red, hot, and dry skin with no sweating, rapid and strong pulse, throbbing headache, dizziness, and nausea.

If the heatstroke victim is not cooled down, he or she may become confused and delirious, or loose consciousness. Treatment involves getting the person out of the sun and into a cool spot, covering him or her with damp sheets, or spraying the individual with water. The victim can also be immersed in a tub of cold water, if possible, and immediate medical assistance should be obtained. Medical care is important because heatstroke kills neary 80% of victims who aren't treated appropriately.

BadwaterDehydration is the principal cause of fatalities in Death Valley. The hot dry air just sucks the moisture out of the human body. You can lose over one gallon of water just sitting in the shade on a summer day in Death Valley. While hiking in the sun, you can lose twice as much!

"The first sensations of thirst begin with the loss of a little over a quart of water," writes naturalist Richard Lingenfelter, describing the progressive stages of dehydration in his book DEATH VALLEY AND AMARGOS. "By the time you have lost a gallon you begin to feel tired and apathetic. Most of the water lost comes from your blood, and as it thickens, your circulation becomes poor, your heart strains, your muscles fatigue, and your head aches. With further loss of water you become dizzy and begin to stumble; your breathing is labored and your speech is indistinct. By the time you have lost two gallons of water your tongue is swollen, you can hardly keep your balance, your muscles spasm, and you are becoming delirious. You are likely to discard your hat, clothes, and shoes, which only hastens your dehydration and suffering. With a loss of more than three gallons of water you will collapse, your tongue and skin shriveled and numb, your eyes sunken, your vision dim, and your hearing almost gone. Bloody cracks will appear in your skin and you'll soon be dead."

Visitors are warned to take special precautions against the heat, says Ed Derobertis, who has worked as a Park Ranger at Death Valley for the last ten years. Man wiping forehead.You should drink lots of fluids the evening before visiting the desert, and dress appropriately: a shirt, sunglasses, and a broad-brimmed hat are necessities. Lots of sunscreen and loose, light clothing are also recommended.

"I don't think that people really understand just how hot it can really be," says Derobertis. "I think people get the false feeling that because this is a National Park, it's safe to come out here. Sometimes, it's not so safe. Last year, one day, it was 129° Fahrenheit. That's so hot that it hurts to get out of your car, and if you do get out of the car you have [to] stay in the shade -- otherwise it's just unbearable."

According to Derobertis, "During the summer, it can be more than 120° in the shade, but that doesn't suggest how hot the ground can become. The rocks and sand absorb the heat and the ground temperature out on those trails can get to be 160°. The trails might be short, but if you are out during the middle of the day, it can really weigh heavily on your body."

To help prevent dehydration, Derobertis advises visitors to "drink [a] minimum of [one] gallon of water a day, and twice that is even better." You should also carry plenty of drinking water in your car and while hiking. Individuals who experience dizziness, nausea, or headaches should get out of the sun immediately and drink lots of water.

-- By Micah Fink


Home | About the Series | Lesson Plan | Credits