The effects of heat on the body are well known: over-heating strains the heart and kidneys, causes headaches, disrupts sleep, and slows cognition. In extreme cases, heat stroke can lead to multi-organ failure and even death! Heat stroke occurs when the body reaches an internal temperature of 104 degrees and above. By this point, blood pressure has often dropped too low for too long, causing internal organs to become deprived of blood and therefore oxygen. This is when bad things start to happen.
As I get older the heat seems to affect me more. I was having this conversation with a few of my older friends last week and we all seemed to agree. When we were younger we never even thought about the heat or cold. We would work outside all day and night and not think twice, throwing hay, loading watermelon trucks, doing flatwork, roofing, etc… I remember my grandparents talking about the heat when they got older, but I always thought it would never happen to me. Wow, was I delusional…
Temperatures this summer are starting to already heat up, and depending on the humidity level, 95 degrees can feel drastically different and overheat some folks. Most are likely familiar with alternative temperatures that are called things like “real feel” or “heat index”, which literally indicate how hot it will feel. For example, 100 degrees in a dry desert area can feel more like 98, while the same temperature in the humid Midwest could feel closer to 110 degrees. It’s the humidity – or the amount of water in the air – that makes all the difference. This is because the more humid it is, the less sweat evaporates off our skin. Sweating is the body’s natural way of cooling itself. The more saturated the air is with water, the less evaporation is going to occur. When the sweat can’t evaporate, our body can’t regulate its temperature and our skin is literally just suffocating in its own sweat.
Low humidity on the other hand makes temperatures seem cooler because sweat evaporates more quickly and efficiently. Humidity is measured in different ways. While most of us may be familiar with the term “relative humidity”, the dew point is a better indicator of the level of water in the air, according to meteorologist Dave Dombek. The dew point is the temperature at which dew would form. The closer the air temperature is to the dewpoint, the more humid the air. Humidity begins to feel even more noticeable as dew points reach between 65 and 70 degrees Fahrenheit. Dew points above 70 degrees are when the air really starts to feel oppressive and anything above 75 degrees is going to feel like a tropical rainforest. Below are some tips on how to stay safe and comfortable through the hottest days of the year. (Sources: Accuweather, WebMD, CDC)Heat Stress: Sometimes just referred to as heat illness, symptoms and signs of heat stress can be subtle. Generally, it can start as just dizziness or a mild headache. As things progress, the person might become confused or disoriented or just act abnormally. Symptoms can also include muscle spasms, heat rash, and heat exhaustion.
Heat Exhaustion: This can be a precursor of the more severe condition known as heat stroke. The symptoms include heavy sweating, rapid breathing, and a fast, weak pulse. Causes of heat exhaustion include exposure to high temperatures, particularly when combined with high humidity, and strenuous physical activity.
- Heavy sweating
- Cold, pale, and clammy skin
- Fast, weak pulse
- Nausea or vomiting
- Muscle cramps
- Tiredness or weakness
- Dizziness
- Headache
- Fainting (passing out)
Heat Stroke: Also known as sunstroke, this is a severe condition can that can kill or cause damage to the brain and other vital organs. The medical definition of heatstroke is a core body temperature greater than 104 degrees, but the first sign may be fainting. Other symptoms can include lack of sweating despite the heat, nausea and vomiting, seizures and rapid, shallow breathing. Heatstroke often occurs as a progression from milder heat-related illnesses, but it can strike even if you have no previous signs of heat injury. If you suspect a heat stroke call 911 right away as heat stroke is a medical emergency. Move the person to a cooler place. Help lower the person’s temperature with cool clothes or a cool bath.
- High body temperature (103°F or higher)
- Hot, red, dry, or damp skin
- Fast, strong pulse
- Headache
- Dizziness
- Nausea
- Confusion
- Losing consciousness (passing out)
Why Working Out In The Heat Can Be Dangerous: When you work out in super hot temperatures, your body sweats a lot to cool itself. Then your blood rushes to the skin to cool it, which means there’s less blood in your muscles. That makes your blood pressure drop and your heart rate go up, which can sometimes cause you to feel lightheaded. As your body temperature climbs higher, you might feel nauseous and put yourself at risk for heatstroke, seizures, and heart rhythm problems. Overall, pushing yourself in this kind of heat is both foolish and dangerous. Many say when the heat index hits 90 degrees, you should head to your air-conditioned gym instead. For example, though the thermometer might say it’s 84 degrees out, when the humidity hits 75 percent, it really feels like it’s 92 degrees outside, according to the heat index chart. That means you’re in the danger zone for working out. For casual exercises, if dew points are in the 70s, particularly in the 80s, it might be a good day to stay inside and workout in an air-conditioned place. Make certain you take additional precautions to hydrate when exercising or working outdoors. The general recommendation is to drink 24 ounces of fluid two hours before exercise, and consider adding another 8 ounces of water or sports drink right before exercise. During exercise, you should consume another 8 ounces of water every 20 minutes, even if you don’t feel thirsty.
“It’s not the heat, it’s the humidity”.That’s a partly valid phrase you may have heard in the summer, but it’s actually both. The heat index, also known as the apparent temperature, is what the temperature feels like to the human body when relative humidity is combined with the air temperature. This has important considerations for the human body’s comfort. When the body gets too hot, it begins to perspire or sweat to cool itself off. If the perspiration is not able to evaporate, the body cannot regulate its temperature. Evaporation is a cooling process. When perspiration is evaporated off the body, it effectively reduces the body’s temperature. When the atmospheric moisture content (i.e. relative humidity) is high, the rate of evaporation from the body decreases. In other words, the human body feels warmer in humid conditions. The opposite is true when the relative humidity decreases because the rate of perspiration increases. The body actually feels cooler in arid conditions. There is direct relationship between the air temperature and relative humidity and the heat index, meaning as the air temperature and relative humidity increase (decrease), the heat index increases (decreases).
In order to determine the heat index using the chart above, you need to know the air temperature and the relative humidity. For example, if the air temperature is 100°F and the relative humidity is 55%, the heat index will be 124°F. It surprises many people to learn that the heat index values in the chart above are for shady locations. If you are exposed to direct sunlight, the heat index value can be increased by up to 15°F. As shown in the table below, heat indices meeting or exceeding 103°F can lead to dangerous heat disorders with prolonged exposure and/or physical activity in the heat. (Source: NOAA, CDC, NWS)
