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The Heat is on: Handling Heat Stress
By Zack French
"Everything looks yellow."
These were the words a fellow tree worker said to me recently during a particularly hot day. He seemed disoriented, and his motor ability seemed to be impaired. It was obvious that it wouldn't be a good idea to send him up another tree. After careful consideration, he was sent home to rest and recover in the refrigerated atmosphere of his home. It was very apparent that he was suffering from an all-too-common ailment during for tree workers during the summer - heat exhaustion, one form of heat stress.
What is heat stress?
Heat stress is defined by the National Institute for Occupational Safety and Health (NIOSH) as heat-induced occupational illnesses, injuries and reduced productivity that occur with excessive exposure to a hot work environment. During summer, we tree people are certainly exposed to these conditions. Usually what little shade we might be under is constantly being cut down around us and by the afternoon, when the sun is highest, we are in the full extent of it, cleaning up what we did in the morning. After a long day in the heat, it's hard not to be affected. If you don't take care of yourself out there, you will likely suffer from some form of heat stress.
Heat stress is grouped into three basic categories: heat cramps, heat exhaustion and heat stroke.
Heat cramps: Heat cramps are muscular pains and spasms due to heavy exertion. They are the least severe form of heat stress; however, they are an early indicator that the body is having trouble dealing with the heat.
Heat exhaustion: Heat exhaustion typically occurs when people exercise heavily or work in hot, humid conditions. Body fluids are lost due to perspiration, and blood flow to the skin increases, which decreases flow to vital organs. This results in a mild form of shock that, if not treated, could eventually lead to heat stroke.
Heat stroke: Heat stroke is LIFE THREATENING! The body's temperature control system stops working, and body temperature rises sharply, often in excess of 103 degrees Fahrenheit. At these temperatures, brain damage is likely and death may occur if medical care is not received.
When does heat stress occur?
The answer to this question is easy - when it's hot! More specifically, however, the chances of suffering from heat stress increase as both the temperature and the humidity in the atmosphere increase. Most people have heard of humidity's relation to heat as the heat index. The heat index is the number in degrees Fahrenheit of how hot it actually feels like outside when relative humidity is added to air temperatures.
Adding humidity to hot air makes it harder to cool down. Sweat or perspiration cools the body through evaporative cooling. As the liquid evaporates, energy is absorbed from the skin. But high humidity decreases evaporation, minimizing the cooling effect of our perspiration. Instead, the sweat acts as a pressure cooker and can actually raise our body temperatures to dangerous levels. The Oregon Chapter of the Occupation Safety and Health Administration (OSHA) has produced a chart illustrating how humidity affects the heat index and increases the likelihood for workers to suffer from heat exhaustion.
What to do for heat stress?
If you suspect that you or someone on your crew is suffering from heat stress, the first thing to do is to put him or her somewhere cool, elevate the victim's feet and give them water. Drinks with a lot of caffeine should be avoided, as well as any carbonated or alcoholic beverages (the latter of which should never be on tree jobs anyhow!). For heat cramps, it helps to stretch the affected muscles lightly.
If you suspect heat exhaustion or heat stroke, further measures should be taken. First, remove or loosen tight clothing and apply cool, moist cloths. Continue to give the victim water at one-half cup every 15 minutes.
A visual inspection of the victim could tell some critical information. If the victim is sweating, then his or her body is still trying to cool itself and therefore you can rule out heat stroke. Also, if the victim's skin is pale, clammy to the touch and flushed, chances are good that you're dealing with heat exhaustion.
However, if the victim is not sweating, his or her skin is hot and dry to the touch and has a hot, red complexion, heat stroke is definitely a possibility. To be sure, take the victim's temperature as soon as heat exhaustion or heat stroke is suspected. If temperatures are normal, they might have heat exhaustion, but they likely aren't in immediate danger. If they have significantly high body temperatures (102 degrees or above), heat stroke is likely and immediate medical attention is required.
What can I do to prevent heat stress?
The easy answer, again, is stay out of the heat. Unfortunately, as tree workers we aren't afforded the luxury of air-conditioned offices, and regularly scheduled breaks are often hindered by a push to get things done. That said, there are several things we can do to make the summer less difficult - and dangerous - than it might be.
The first thing to remember is to always have plenty of water available. Companies should provide crews with water, or at least a container to fill in the morning. If there isn't one on your truck, urge your employer to provide one. Drinking water is the most important factor in staving off heat stress. It is how we cool ourselves and it is important in our biological functions. Without it, just like the trees and shrubs we care for, we shrivel and die.
Second, take frequent breaks. We have a very physically demanding job. It is important to find shade and cool down for five to 10 minutes every few hours. In the heat of the summer, frequent breaks relieve the body between climbs or trips to the chipper.
Another suggestion is to work fewer hours or fewer days. I know some company owners are groaning at this suggestion. "It's the busiest time of the year! We'd lose too much production!" Those who doubt me, consider this: a rested worker is a productive worker while an exhausted worker may well be next to useless. You might find you get better production out of your workers in fewer man-hours during the summer if you work less than if you push long and hard for an extended period of time.
Also, try working earlier in the day. Early to rise makes a man wise and also keeps him cool by letting him work a full day and quit before the heat gets unbearable in the afternoon. The earlier the start the better, though this is somewhat limited by the fact that you can't get out too early and start the chain saws without someone complaining.
Another thing to consider are lightweight, light colored clothes. Company colors notwithstanding, it is important to wear something that will breathe and reflect some of the sun's heat. Also, remember to keep this clothing on! It may seem like a good way to cool off by shedding a shirt in the hot sun, but the resulting sunburn is only going to make you more susceptible to heat stress.
On that topic, let's briefly consider PPE in summer. Hardhats and chaps are the biggest complaint in my area for being hot in the summer. However, it is critical that we wear them anyway. Some ways to make hardhats more bearable are to keep them clean and fitted properly. Wearing hair shorter in the summer also allows air to better circulate underneath the hardhats, keeping heads cooler.
As far as chaps go, we are required to use them any time we are using a saw on the ground (and for good reason). It's well worth the extra 10 seconds to put them on and take them off before and after using the saw, and if regular breaks are used to relieve operators, heat stress shouldn't be a problem, even in the hottest climates.
Conclusion
Summer is tough. Every year I wonder how it came to pass that I chose to spend the hot days hauling and loading hundreds of pounds of wood into a truck after hauling hundreds of pounds of me up and down a tree for hours on end in unrelenting heat. Somehow I make it through it and by fall I'm preparing for the other end of the mercury scale. Knowing how to deal with heat stress took a long time for me to learn but, hopefully, after reading this article you should have a good idea how to keep you and your crews safe during the hot summer.
Zack French is a Certified Treecare Safety Professional, Board Certified Master Arborist and Registered Consulting Arborist working as an independent contractor and operations consultant in Nashville, Tennessee.
References:
American Red Cross article: "Are You Ready for a Heat Wave?" www.redcross.org/static/file_cont203_lang0_93.pdf
American Red Cross Web page topic: "Heat Waves" www.redcross.org/services/prepare/0,1082,0_243_,00.html
Feazell, P. 2008. Personal communication with Pam Feazell, registered nurse, retired.
National Ag Safety Database Web page topic: "Heat Stress" www.cdc.gov/nasd/docs/d001701-d001800/d001702/d001702.html
NIOSH Safety and Health topic: "Heat Stress" www.cdc.gov/niosh/topics/heatstress/
OSHA publication, 2006. The Heat Equation Oregon OSHA web site www.orosha.org/pdf/pubs/3333.pdf
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