The Effects of Humidity on the Human Body

Humidity Effects on the Human Body

As discussed in Home Humidity and Allergies, humidity directly affects the amount of allergens in the indoor environment. In particular, high humidity causes both dust mite populations and mold colonies to grow, thereby greatly increasing allergy sufferers' total allergen load.

But, as may seem obvious, even non-allergic individuals suffer from the effects of high humidity. No one enjoys sticky hot weather. But have you ever wondered why moist, hot air makes us feel so awful? This article explains the effect of humidity on the human body, and why keeping humidity levels within range is a matter not just of keeping allergies under control, but of safety as well.

Humidity Makes it Hotter

Heat Index

One reason humidity makes hot weather more unbearable is that the higher the relative humidity, the higher the temperature actually feels. For instance, a temperature of 95 degrees feels like about 95 degrees when the relative humidity is 30%. But bump that humidity up to 65% and that same 95 degrees feels like a whopping 117 degrees! A heat index chart lets us know what the temperature on any given day will feel like 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

When outside temperatures approach the temperature of the human body (about 98 degrees) 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.

Sweating, however, only works to cool us down if the water that is expressed through the skin evaporates. This is where humidity comes in. The concentration of water, or the relative humidity, determines the rate at which the water can evaporate from the skin. When the air is more full of moisture, it is harder for the air to absorb the sweat from our skin. The result? We feel hot and sticky, and the body is eventually forced to do other things to cool us down.

The Danger of High Humidity

The Weather DoctorThe problem with high humidity making us feel hotter is not just that we are more uncomfortable, but that we actually are hotter. 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 and chemicals that the body needs. Overheating, or more commonly, heat exhaustion, can lead to dehydration and chemical imbalances within the body.

As expressed on The Weather Doctor, “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 (courtesy of USA Today):

  • 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 exercising 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 degrees. 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 degrees 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.
Danby 70 Pint Dehumidifier

Key ways to avoid overheating are firstly, 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.

Keeping indoor air at a comfortable and healthy humidity level through the use of a dehumidifier is also important. While an air conditioner may remove some of the moisture from the air inside your home, a dehumidifier is built specifically for that purpose. Often times you can not only control the humidity, but also the temperature inside your house by simply using a dehumidifier. In addition to creating a more comfortable environment, a dehumidifier also works to reduce allergens that often thrive in warmer, more humid conditions.


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