As I write this, a lethal heat wave is turning the central United States into a blast furnace, and multiple cities in the Plains are hitting temperatures well above 100 F. In the United Kingdom, heat records are falling with frightening ease.
Working outside in winter is tough, but summer heat can be more dangerous
For the men and the women on the job site, the summer heat can be a thornier issue to deal with than winter cold. Unfortunately, we’re not always as careful in the summer as in winter. Yes, the sweat is dripping into your eyes and, yes, the back of your neck is feeling the roasting rays of the sun, but your body is less adept at sending signals to your brain that you’re in trouble.
Part of the reason is we get discombobulated and the heat oppression can be cumulative. Recently, I spent a couple of days rebuilding our deck. After two days in the sun, I wasn’t thinking with my usual sharpness. While filling the car at the gas station after the second afternoon of working in the sun, I forgot to remove the hose from the tank and drove away, pulling the hose from the pump. Fortunately, there’s a breakaway spot on the hose, so no damage was done and no gas was spilled, but the accident was purely because I wasn’t able to concentrate on a task that I’ve done my whole life.
As wet-bulb temperatures approach 95 F, even the healthiest people, relaxing in the shade without heavy clothing and with an endless supply of water, cannot prevent themselves from overheating. Even at lower wet-bulb temperatures, like 79 F, those with preexisting health conditions … as well as those performing strenuous outdoor labor … are at a high risk.
Such a lapse of concentration on a job site can have much more catastrophic results. During these hot days, regular hydration breaks in the shade are essential for workers to be safe and to function fully.
But even the shade might not be safe in some places. Have your heard of wet-bulb temperatures? It’s measured by a thermometer covered with a wet cloth, and is a measurement of heat and humidity. At 100% humidity, the wet-bulb temperature is equal to the dry-bulb temperature.
In a wet-bulb temperature of 95 F or higher, your body essentially runs a fever with no way to cool it down—even in the shade. The high humidity prevents the sweat from evaporating from your skin, which keeps your body cool. An hour of working on a wet-bulb temperature day can be life threatening.
Fortunately, such days are not common, but here’s the danger. According to Radley Horton, a Columbia University professor who co-authored a National Oceanic & Atmospheric Administration (NOAA) 2020 study on wet-bulb temperatures, “Wet-bulb temperatures above 86 F are rare in the U.S. As wet-bulb temperatures approach 95 F, even the healthiest people, relaxing in the shade without heavy clothing and with an endless supply of water, cannot prevent themselves from overheating. Even at lower wet-bulb temperatures, like 79 F, those with pre-existing health conditions (like respiratory, cardiovascular and renal disease), the elderly, as well as those performing strenuous outdoor labor and athletic activities, are at a high risk.”
They’re not common, but they are becoming more common, especially in the Southeastern United States along the Gulf Coast. There are a whole lot of construction workers between East Texas and the Florida Panhandle. They should know the dangers of high heat and high humidity. And in 50 years, according to NOAA, several states in the Midwest are likely to see significant increases in wet-bulb temperature days.
Want more information? Check out the NOAA study, “The Emergence of Heat and Humidity Too Severe For Human Tolerance,” at research.noaa.gov and also Senior Editor Mark Robins’, feature article, “Protecting Construction Workers from Heat Stress,” in the June issue.
