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After a week of excessive heat and humidity, with temperatures reaching into the upper 90s (degrees Fahrenheit), the Northeast heat wave is finally drawing to a close. Living in New York City, I was one of its ""lucky" victims, and trust me when I say, it was brutal! Stepping out of my air-conditioned house felt as if I were entering a sauna, and walking to the store left me drenched in the most repulsive layer of sweat. The high heat index made the temperature feel as if it exceeded 100 degrees, and accompanied with the absence of even a slight breeze, it made this week truly miserable.
Although some people may be thinking, "Boy, does she complain a lot! What's a little heat ever done?" let me tell you: a "little heat" has done A LOT. Besides causing millions of people that normal discomfort that we are all familiar with, heat waves pose actual health risks and illnesses that, at times, can be fatal. From dehydration to heat exhaustion to heat strokes, the health effects of the heat and sun are nothing to take lightly, especially considering that these illnesses cause an average of 675 deaths each year in the United States alone. Many people do not understand the dangers of the heat on their health, so by writing this blog, I hope to raise people's awareness so that they can be smarter in the sun.
Thermoregulation
The human body is programmed so that the standard, core temperature is 98.6 degrees. It is at this temperature that the body functions best, and when it exceeds or falls below this mark, it relies on thermoregulation to regulate the temperature and restore it back to homeostasis. When one is exercising, becomes nervous, or just steps out of the house on a very hot day, the body temperatures may rise, but luckily, the body knows just what to do to lower it. When you were younger, you might remember your parents telling you in the winter to put on your hat before playing outside in the snow because they believed that most of your body heat was released from your head. Well, in the summer, it is this same body heat that, when released through the processes of conduction and convection, cools one off. However, many times, this release of body heat is not sufficient by itself to cool down the body, and so, the body has the beloved mechanism of perspiration, aka sweating. When one sweats, water and other molecules (sodium chloride, potassium, magnesium, etc) are released from the body's 2.6 million sweat glands. As the sweat reaches the surface of the skin, it evaporates off of the body, taking excess heat along with it. It is this evaporation of sweat that makes the body become cooler, and thus return to 98.6 degrees.
Dehydration, Heat Exhaustion, Heat Strokes
Although sweating is one of the primary mechanisms that the body uses to cool off, at times, the humidity in the air can get in its way. The more humid the air is, the more water molecules it contains, and the less the air will "want" to evaporate sweat. If the relative humidity is 100%, which means that the outside air is already saturated with water molecules, sweat evaporation will not take place, and the body will not be able to rid itself of its excess heat. When this happens, and sweat won't evaporate, the body's thermoregulation mechanism is defeated and the body temperature will still be high.
On the contrary, in areas of dry heat, where the air is not humid, it is easier to cool down by perspiration, because the dry air can "accept" more evaporated water molecules from the body. However, in such dry conditions, it is vital that one drinks a sufficient amount of water to replenish the water that has been loss by perspiration, as well as replacing the salt that has been evaporated. During a heat wave, a person can sweat up to 1.5 quarts of liquid every hour, so it is very important that one drinks enough each hour to make up for this loss. When a person does not drink enough water to replenish the body's supply, dehydration will occur, and this can prevent the body from sweating and carrying out its functions. If the body cannot sweat, body heat builds up, and high temperatures along with dehydration can cause blood flow to slow down and vital organs to shut down. When this happens, the body ceases to work properly.
Heat exhaustion is a major risk during heat waves because when people are exposed to a prolonged exposure to the sun, they begin to sweat profusely and dehydrate. Their body produces more heat than it can dispose of, and soon they experience weakness, cramps, and headaches. If care isn't given to the person suffering from heat exhaustion, that person is at risk of getting a heat stoke, in which the body's core temperature exceeds 105 degrees. This can damage the brain and other organs in the body, including the heart and kidneys. When the brain is damaged, people do not think correctly, and they can make rash decisions. They can also experience symptoms such as disorientation, seizures, and loss of consciousness. This form of hyperthermia can be fatal if the patient is not treated immediately.
Dangers of Ozone
One interesting, indirect effect of the extreme heat during heat waves involves ozone uptake by plants. It has been known that plants and other vegetation reduce air pollution by absorbing pollutants such as ozone, but according to a recent study published by the University of York's Stocholm Environment Institute, in times of great heat, plants shut their stomata in efforts to conserve water, and in doing so, the amount of pollutants they absorb decreases tremendously. The study has found that due to the shutting of the stomata alone, the amount of ozone has increased to such a point where it caused 460 deaths around the United Kingdom in the summer of 2006. Seemingly, these deaths could have been prevented if the temperature outside was not as high, thus allowing the plants to keep their stomata open and absorb more ozone.
As you now know, it is not all that fun in the sun. Heat related emergencies are real, and they can happen very quickly. I am sure that there will be plenty more hot days in the summer weeks to come, so please pay heed to the heat warnings and take the proper precautions to protect yourself and your loved ones. Please do not leave your children in the car while you run into the store, because in just 20 minutes, that car can heat up to over 120 degrees, and this year alone, 22 children left in cars have died from a heatstroke. Also, keep an eye out for the elderly- whether they are your friends, family, or neighbors, and don't forget about your pets! Heat emergencies and illnesses can affect our dogs, cats, and other animals, so please make sure that you pay special attention to them as well.
Be safe and enjoy the rest of your summer!
Picture Credits
Beach: Howard Brier (via Flickr)
Vegetation: Jasmin (via Flickr)
Sources:
Brink, Susan "How 100 Degrees Does a Number on You" National Geographic July 15, 2013
"CDC Urges: Stay Cool to Stay Healthy as Temperatures Soar" Centers for Disease Control and Prevention July 25, 2011
Emberson, L.D; Kitwiroon N; Beevers S; Buker; Cinderby S; "Scorched Earth: How Will Changes in the Strength of the Vegetation Sink to Ozone Deposition Affect Human Health and Ecosystems" Atmospheric Chemistry and Physics 2013
"Heat Exhaustion" MedicineNet.com May 22, 2013
“Heat Illness” Kids Health
"Heat Stroke: Symptoms and Treatment" WebMD
"It's Not Just Heat, It's the Ozone: Hidden Heat Wave Dangers Exposed" University of York July 19, 2013
Null, James “Heatstroke Deaths of Children in Vehicles” San Francisco State University’s Department of Geosciences July 19, 2013
