EFFECTS OF HUMIDITY ON THE BODY
This week we are projected to see very high humidity in Texoma. Ever wonder why humidity makes hot weather feel higher than the actual temperature?
For instance, a temperature of 95° feels like 95° when the relative humidity is 30%. But bump that humidity up to 65% and that same 95° feels like a whopping 117°! The heat index chart factors relative humidity into temperature to provide a more accurate assessment of what the temperature feels like. This is similar to what you see during the winter months regarding “wind chill”. In that instance, the speed of the wind is factored into the temperature to give a more accurate reading of how cold the weather actually feels to us.
But why does humidity make it feel hotter? To understand this, we have to understand how our bodies cool us down.
HUMIDITY HAMPERS THE BODY’S COOL-DOWN MECHANISM
Though we do not often think of it, we are inherently fragile creatures. Something as seemingly small as a five degree drop in body temperature can have severe health consequences, including hypothermia. Five degrees higher and the human body begins to experience hyperthermia. On either end of the spectrum, when the core body temperature begins to deviate from the norm, problems can occur.
When outside temperatures approach the temperature of the human body (about 98°) the body undergoes a series of changes to help keep it cool. Sweating, alteration of the rate and depth of blood circulation, and increased respiration are all measures the body takes in an effort to cool itself down and shed excess heat.
Sweating, one of the key cooling mechanisms of the body, only works to cool us down if the water that is excreted through the skin, evaporates. This is where humidity comes in. The concentration of water in the air, relative to the temperature (relative humidity) determines the rate at which the water can evaporate from the skin. When the air is holding more moisture (relative to the total moisture it could hold at that temperature), it is harder for the air to absorb the sweat from our skin. The result? We sweat and sweat but instead of feeling any relief, we simply feel hot and sticky. With high relative humidity subverting the cooling ability of sweating, the body is eventually forced to do other things to cool us down.
THE DANGER OF HIGH HUMIDITY
The problem with high humidity making us feel hotter is not just that we are more uncomfortable, but that our core temperature is actually rising, and our bodies compensate by working harder and harder to cool us down. When sweating doesn’t work to cool us down and we continue to heat up, overheating results, which causes loss of the water, salt, and chemicals that the body needs. 
Overheating, or as it is more commonly known, heat exhaustion, can lead to dehydration and chemical imbalances within the body.
Dehydration depletes the body of water needed for sweating and thickens the blood, requiring more pressure to pump it through the body, thus straining the heart and blood vessels. As blood goes to the external surface of the body, less goes to the muscles, the brain, and other organs. Physical strength declines, and fatigue occurs more quickly than under normal conditions. Mental faculties, such as alertness, may also be adversely affected.
Such effects are more pronounced, and more dangerous, depending on age and overall physical condition. However, young people that aren’t aware that their physical activity or exercise could be dangerous in humid conditions, are also at risk. Overheating is a serious condition, and can result in the following:
- Heat cramps: Exercising in hot weather can lead to muscle cramps, especially in the legs, because of brief imbalances in body salts. Cramps become less frequent as a person becomes used to the heat.
Heat syncope or fainting: Anyone not used to exercise in the heat can experience a quick drop in blood pressure that can lead to fainting. As with heat cramps, the cure is to take it easy.- Heat exhaustion: Losing fluid and salt through perspiration or replacing them in an imbalanced way can lead to dizziness and weakness. Body temperature might rise, but not above 102°. In some cases, victims especially the elderly, should be hospitalized. Heat exhaustion is more likely after a few days of a heat wave than when one is just beginning. The best defense is to take it easy and drink plenty of water. Don’t take salt tablets without consulting a physician.
- Heatstroke: In some cases, extreme heat can upset the body’s thermostat, causing body temperature to rise to 105° or higher. Symptoms are lethargy, confusion and unconsciousness. Even a suspicion that someone might be suffering from heatstroke requires immediate medical aid. Heatstroke can kill.
Key ways to avoid overheating are first, to be aware of not only the temperature, but the heat index; to drink plenty of water; and to take it easy, slow down, and cool off when noticing any sign of fatigue, headache, or increased pulse.
Remember to drink small amounts of water often (before you become thirsty). You should drink about 4 cups of water every hour while the heat index is 103 to 115°F. You need the greatest amount of water if working in direct sunshine, during peak exertion, and during the hottest part of the day. As for how much water you should drink, there is no easy one-size-fits-all answer, and the standard “8 glasses of water a day” isn’t necessarily accurate. (It’s popular because it’s easy to remember).
The adequate fluid intake for a man living in a moderate temperate climate is about 13 cups of liquid per day. For a woman living in a moderate temperate climate is about 9 cups.
One “rule” to remember when working our exercising outside…. keep an eye on the color of your urine. The clearer, the better. If urine is very yellow or dark, you know you need to go drink some water.
Here is a neat Hydration Calculator presented by Camelbak…. Yes, the same hands free Camelbak product that was born from our own Hotter ‘N Hell 100.