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| Kentucky National Guard / Flickr |
The Heat Index
The heat index is the combination of the air temperature and humidity and how it affects our skin, body, and health. The National Weather Service will give you the heat index (or the Feels Like Temperature) along with other readings every hour.
The higher the humidity the higher the heat index will usually be. For example, if it is 90° F with a humidity of 60%, it will actually feel like it is 100° F. If you raise the humidity to 70%, the heat index jumps to 109° F. So an air temperature of 90° F can actually affect your body as if it was 109° F out.
The heat index was devised for the shade and light winds, being in full sunshine can increase this heat index temperature by as much as 15° F.
This is why it is important to understand and pay attention to the heat index. A heat index at or above 105° F is in the danger to extreme danger category. The NWS will issue excessive heat watches and heat warnings when dangerous heat indexes are expected or are occurring.
Heatstroke is Deadly
Hot weather especially combined with higher humidity should not be taken lightly. In the United States, heatstroke is the number one weather-related cause of death.
A 10-year average shows that heat and heatstroke killed on average 237 Americans per year. In the 1980 heat wave, 1,270 Americans were killed and in the 1995 heat wave, more than 700 people died in Chicago alone.
The United States isn't the only place where heatstroke is a concern. In 2003, a severe heat wave hit Europe where an estimated 50,000 people were killed by heatstroke and heat-related health problems.
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| Heat alert on television / jalbertgagnier/Flickr |
How Heatstroke Occurs
This causes the sweat glands to draw water from the blood so it can put water on our skin to cool us. Our body will pump more blood to keep the body cool and this is why excessive heat can put a strain on the heart.
A healthy heart is more able to keep up with the demand of the body's need to pump blood during the heat. The older you are, the more susceptible to heatstroke you are.
When the sweat on your body evaporates it turns into water vapor and this process takes energy which cools your skin and body, the energy of evaporation takes heat off of your body.
When the humidity is high and the heat index is high, this evaporation might not occur or occur as quickly. Even though the sweat isn't evaporating at a normal rate under high humidity and temperature, your body continues to sweat. And the hotter your body is getting the more you are sweating.
When we sweat, we are losing water and minerals and the loss of these minerals causes an imbalance in our body which can lead to heat-related illness including heatstroke.
The Stages and Symptoms of Heatstroke
Stage two is heat exhaustion and is characterized by more water and mineral loss (electrolytes) through excessive sweating. The symptoms of heat exhaustion are excessive sweating, dizziness, disorientation, lethargy, and vomiting. The skin can sometimes actually feel cool.
Stage three is heatstroke and the symptoms are the above symptoms and possibly a body temperature of 105° F, rapid shallow breathing, seizures, and possibly coma. In children, the symptoms can include an inability to sweat any more.
How to Prevent Heatstroke
This is why you have to drink plenty of water, even if you're not thirsty. We hear this so much that we tend to ignore it. We need to drink a lot of water on these hot days and nights especially when the heat index is high with high humidity.
By drinking plenty of water we are replenishing exactly what our body needs to keep us cool. Use the following tips to prevent heatstroke.
- Drink plenty of water
- Avoid alcohol. Alcohol is dehydrating and will make the heat worse
- Eat smaller and lighter meals. Eating a heavy meal will cause your body to become hotter while digesting the food.
- Take breaks, find shade and rest until you cool down.
- Have a fan blowing air on you.
- Go to an air conditioned mall, ice rink or a friends or relative's house with air conditioning during a heat wave.
How to Treat Heatstroke
Heatstroke can come on you without you even realizing it and that is what makes it so dangerous. I will relate a story about a camping trip in South Dakota. Everyone was sitting around talking when they noticed a woman was starting to talk incoherently.
There was no alcohol involved so they realized she was on the verge of getting heatstroke. She said she was fine and refused to drink water until she realized she couldn't stand up. They forced her to drink water, which she did throw up at first.
Finally, she was able to drink enough water and the health crises passed. If this had continued they would have taken her to a hospital. If you're with someone who is showing the signs of heatstroke, do the following:
- Give the person water or a drink that will replace the electrolytes. A drink like Pedialyte is very good as are some sports drinks.
- Move them to a cool place.
- Loosen or remove tight clothing.
- Cool the body with wet towels or ice bags. Put the ice bags on the wrists, ankles, armpits and the neck to cool the person.
- Do not use rubbing alcohol since this can close the pores and prevent sweating.
- Fan the person.
- Give the person a half a glass of water every 15 minutes and don't let the person drink too quickly.
- Do not give the person alcohol or beverages that contain caffeine, this will make the condition worse.
- If the person is showing signs of heatstroke and does not improve, call emergency 911 or get them to a medical clinic.
Children, the Elderly and Pets During a Heat Wave
Leaving the windows partially open does not help. The inside temperature of a car can heat up 50° F or more in under an hour reaching temperatures of 145° F or higher, with the heat index even higher.
Children, the elderly and pets can get heatstroke quickly. During a heat wave, check on elderly relatives and friends.
About the Author
Sam Montana is a certified Food Over Medicine instructor from the Wellness Forum Health Center and certified in optimal nutrition from the Harvard T.H. Chan School of Public Health.
© 2010 Sam Montana
