Four Things Extreme Heat Does To Your Body

Extreme heat should be taken seriously by everyone, but especially children, the elderly and those with health issues.

What is extreme heat? The definition varies by region, but usually requires temperatures at least 10 degrees above average. However, generally temperatures of 90 degrees or above, accompanied by high humidity levels and resulting in high heat index values, is considered extreme heat. This type of heat typically occurs when a strong upper-level area of high pressure develops over a region, causing the air to sink and warm.

The good news is that if proper precautions are taken, heat-related health issues can be avoided. In most cases, staying hydrated and getting into a cool environment can avoid serious health problems.

(MORE: 15 Summer Health Myths)

However, in order to prevent health issues caused by the heat, you need to be aware of the potential consequences first. Here are four things that can happen to your body during extreme heat events.

1. Heat Makes You Feel Ill

Some of the first signs that your body is beginning to have trouble due to extremely hot temperatures are increased sweating and muscle cramps. 

When you sweat, you are losing water, and if you do not replace the amount you are losing, an imbalance in salt can result, causing cramps. 

In addition, if your sweat pores become blocked, a heat rash, or tiny red dots on your skin, can develop. Another issue that can occur is heat edema, which is when your body dilates your blood vessels in order to avoid overheating, and blood can pool in the legs, especially if the balance of salt in your body is off. The end result can be swelling in the legs, feet or hands.  

Prolonged exposure to extreme heat can also result in dizziness and confusion. These conditions are also the result of the increased blood flow to dilate the blood vessels combined with loss of fluid through sweating. Fainting can even occur once enough fluid has been lost and if there is a drop in blood flow to the head as more fluid moves into your legs due to gravity.

Other potential physical impacts are nausea, diarrhea, headache and fatigue. These can result when sweating doesn't cool the body enough on its own and when someone is dehydrated.

2. Heat Exhaustion Can Set In

Heat exhaustion can set in when your body is depleted of either water or salt, due to exposure to the heat.

Symptoms of heat exhaustion include:

• Dizziness or fainting
• Confusion
• Excessive sweating
• Dark-colored urine
• Cool, pale or clammy skin
• Headache
• Nausea or vomiting
• Rapid and weak pulse
• Muscle cramps
• Fatigue

If you start to exhibit these symptoms, it's very important to get out of the heat, drink nonalcoholic and decaffeinated beverages, take a cool shower and rest. 

An even more serious condition is heat stroke, which can develop if heat exhaustion is not treated. The National Weather Service office in Springfield, Missouri, shared some of the differences between heat exhaustion and heat stroke.

3. Heat Stroke Is A Possibility

Heat stroke is the most serious form of heat injury, according to the Mayo Clinic, and is usually the result of prolonged exposure to or physical exertion in high temperatures. However, the elderly, children under age 4, those living in homes without air conditioners and people with chronic diseases are also at risk for developing heat stroke.

• Body temperature above 103 degrees
• No sweating
• Severe headache
• Confusion or disorientation
• Red, hot and dry skin
• Nausea or vomiting
• Rapid pulse
• Seizures
• Loss of consciousness
• Muscle weakness or cramps

Heat stroke is an emergency that needs immediate medical treatment, as it can cause damage to your brain, heart, kidneys and other muscles. It often occurs from the progression of milder heat-related illness, but can come on suddenly as well.

4. You Could Die

On average, 130 people in the U.S. die from heat each year, according to the National Weather Service, based on data from a 30-year period. This is more than any other weather event.

(MORE: Heat Is The Deadliest Kind Of Weather)

Many of these deaths occur during heat waves, which is a period of abnormally and uncomfortably hot and humid weather that can last for several days to weeks.

When temperatures become dangerous varies wildly, based on an individual’s acclimation to the climate, dress, exertion level and whether any pre-existing conditions, such as heart disease, are present, said Michael N. Sawka, Ph.D., a physiologist with Georgia Tech, previously with the Department of Defense, who has studied human adaptations to extreme weather for 40 years.

“If you’re a trained athlete, and you’re working hard, you can go out and run at very high temperatures — 104, 105 [degrees Fahrenheit],” he said. “The harder you work at higher temperatures, you build up a tolerance for the body to respond.”

Sawka explained that the body cools itself in two ways; when these abilities shut down, problems begin.

First, there’s evaporation, when sweat evaporates off of the skin, cooling the body. Second, there’s convection, or a transfer of heat to the skin. During this process, the body shunts blood away from the core toward the surface of the skin for cooling. 

“If you’re wearing heavy clothes, that reduces the ability for evaporation,” Sawka said. “Another factor is how hard you’re working. If you’re sitting, you’re not producing more body heat — because a byproduct of skeletal-muscle contraction is heat — so the harder you work, the greater the body heat you have to dissipate due to the environmental conditions.”

When these processes become ineffective, an individual might progress to heat exhaustion. During this phase, heavy sweating, a rapid pulse, cramps or a headache can occur. Typically, once a person seeks shade and water, he or she is fine.

The Centers for Disease Control and Prevention (CDC) and the National Oceanic and Atmospheric Administration (NOAA) offer some tips to stay safe in extreme heat:

• Stay in air-conditioning as much as possible.
• Slow down and reduce, eliminate or reschedule strenuous work or recreational activities until the coolest time of the day.
• Take frequent breaks during work or play.
• Drink more water than usual.
• Avoid using the stove or oven to cook.
• Take cool showers or baths.
• Wear lightweight and light-colored clothing.
• Check on friends and neighbors.

Those who exercise outdoors and the elderly should also take care to adapt to heat slowly and plan for safe cooling all season long.

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