The Heat is On

Photo by Ketut Subiyanto: https://www.pexels.com/photo/man-in-black-crew-neck-t-shirt-drinking-yellow-liquid-from-plastic-bottle-4719950/

Summer has officially started in the Northern Hemisphere, although summer-like weather arrived well before summer did. Even so, the hottest part of the year is still yet to come.

Every year we get warnings from multiple sources to stay hydrated and watch out for the symptoms of heat exhaustion and heat stroke, but it’s easy to dismiss those warnings and/or get caught up in activities out in the heat and wind up in pretty dire circumstances.

Even those who are well aware of the dangers of excess heat and who do take precautions can be taken by surprise, especially when environmental conditions are different from what they’ve adapted to.

This can be when the temperature is substantially higher than one is used to (as has been the case in some parts of the country recently) and/or when the humidity is higher – even if the temperature is not particularly high.

There’s been quite a bit of news recently concerning a climate phenomenon known as the “wet bulb temperature.” Now, actual wet bulb temperature is not really an issue in the the United States, but the basic principle is useful to understand when it comes to one’s heat tolerance.

Wet bulb temperature is the condition in which the humidity at a given temperature and atmospheric pressure is high enough to prevent evaporative cooling, such as from a wet sleeve wrapped around a thermometer bulb (where the name “wet bulb” comes from), or more significantly to health, from sweat on the human body.

At wet bulb temperature, the body’s temperature will continue to rise regardless of sweating, eventually leading to death if the person does not find a way to cool down – even drinking massive amounts of water won’t help, because producing more sweat won’t cool you off.

Climate scientists used to think that wet bulb temperature would never occur naturally on earth, but in fact it has started to occur periodically in several parts of the world, so it has become a subject of interest from a climate standpoint.

But again, actual wet point temperature is not currently a health concern in the United States, but even heat and humidity combinations well below wet point can be very dangerous and tricky to compensate for, particularly if you’re not used to those particular conditions.

For example, here in South Central Texas, summertime temperatures routinely hit 100 degrees or higher. But we generally have relatively low humidity at the same time, so sweating does a pretty good job of cooling us down, provided we have adequate hydration to keep the sweat flowing. But if we get some rain, the humidity can rise rapidly and even if the temperature is lower, sweating becomes less efficient at keeping our body temperatures in check.

So, even someone who is well-adapted to our usual heat may become quite susceptible to heat exhaustion or even heat stroke when the humidity is higher than normal. With high humidity, hydration is less effective in mitigating the heat. While drinking water is still important, going someplace cooler (or perhaps applying ice or cold packs) periodically may be more important for avoiding overheating when the humidity is high.

So, the basic tips for avoiding heat-related illness come down to:

1) Avoid being outside in the hottest part of the day, if possible. Try to do any work or exercise in the early morning or after the sun goes down.

2) Stay well-hydrated by drinking water frequently. The CDC recommends that people working or exercising in hot conditions drink 8 ounces of water every 15 to 20 minutes (do not drink more than 50 ounces an hour to avoid sodium imbalance).

3) Stay out of the direct sun as much as possible to minimize additional heating of your body from the sun’s infrared rays. Unlike with ultraviolet rays that cause sunburn, neither clothing nor sunscreen will decrease the heating effect of the sun, so seek out shade or cover when possible.

4) Take breaks from the heat to go to a cooler area periodically (at least 15 minutes every hour), or use some type of external cooling method such as applying cold packs to your head, neck, and torso. This is particularly important when the humidity is extremely high (90% or higher).

5) If you start to feel nauseous, weak, severely fatigued, cold, dizzy, or start to get muscle cramps, stop what you’re doing immediately, try to find a cool place to rest, drink some water, and call for help. These are signs of heat exhaustion, which left unchecked may progress to heat stroke - in which case you may lose consciousness or become too confused to get help on your own. Don’t try to “push through” or “tough it out” – try to cool off and get help while you can!

One last tip – DO NOT exercise in the hear wearing a sauna suit or thermal clothing! Every summer I see at least a few people exercising outside during the hot part of the day wearing these types of clothes. They will not help you lose weight, other than some water weight temporarily, and they will put you at high risk of heat exhaustion/heat stroke!

Enjoy the summer, but do it safely!

Until next time…

George F. Best, D.C.