
Responding to Heat Stress on Construction Sites: Dry Heat vs. Humid Heat
Heat stress occurs when the body’s natural temperature regulation methods begin to fail. Construction workers are at an increased risk of it since they spend long hours outdoors doing physically demanding tasks. Unmanaged heat stress can lead to dehydration, muscle cramps and concentration difficulties, all of which could increase the chances of workplace injuries. It can also exacerbate existing conditions, such as heart disease and diabetes.
Both dry heat and humidity can increase construction worker dangers, but they can be reduced through better awareness and quick responsiveness to emergencies.
DRY HEAT VS. HUMID HEAT
Dry heat is most common in desert regions. Although it includes high temperatures, the air has a comparatively low moisture content. Conversely, humid heat features elevated temps and high RAF—relative air humidity—percentages.
Scientists exposed participants to five temperature/humidity combinations, with the lowest temperature being 82.4 degrees Fahrenheit and 50% RAF chosen as the most humid setting. Scientists raised the temperature to as high as 122 degrees Fahrenheit during the experiments, though the RAF was only ever either 25% or 50%. The researchers also tracked numerous participant metrics in each setting.
The results showed a 35% increase in their metabolic rate in 104-degree temperatures and 25% RAF. However, the change reached 48% at 104-degree temperatures and 50% RAH. The metabolic rate is significant because it indicates the energy the body must exert to maintain the ideal core temperature. Additionally, these findings were for subjects at rest, so the outcomes could be substantially different for construction workers or others outdoors.
HEAT EFFECTS ON OUTDOOR WORKERS
People who get too hot in humid-heat environments sweat, but this is not the most optimal way to keep cool. Relatedly, the depletion of the body’s moisture and electrolytes can pose dehydration risks. Extremely humid outdoor environments also disperse pollution less effectively, making some individuals more sensitive to poor air quality. Additionally, they can narrow the airways, exacerbating breathing problems for people with asthma.
The authors of a 2023 research paper discussed the significant debates surrounding the role of humidity in heat-related health outcomes. One finding was that most hospitalizations or deaths do not directly occur because someone’s core body temperature gets too high.
Instead, humid heat is more likely to exacerbate existing health conditions, making catastrophic outcomes more likely. The researchers also acknowledged the lack of applicable studies on the subject, especially since most occur on people at rest rather than those working outside in demanding environments.
However, dry heat also threatens outdoor workers. One of the main issues is that people may not recognize they are getting hot because their sweat evaporates more quickly.
Additionally, they may urinate less often, prompting them to determine that they can drink less water. That happens because the body releases more antidiuretic hormones into the bloodstream to signal to the kidneys to preserve fluids. Excessive throat and face dryness can also occur due to prolonged periods of dry heat.
In one study, researchers subjected participants to dry heat and humid heat while they either rested or engaged in seven five-minute bouts of cycling. The outcomes showed almost all physiological stress indicators were higher in the dry heat than in humid heat. For example, people’s heart rates were faster and their core temperatures higher, suggesting a greater potential for cardiovascular stress.
RESPONDING TO HEAT STRESS ON CONSTRUCTION SITES
Although some effects of heat differ depending on the type, the associated emergencies require the same first aid. Prompt action reduces the risk of complications:
1. Move the Person to a Cool Area
Affected workers should be brought to a shaded or air-conditioned place so they can start getting relief from the temperature. If possible, they should lie down with their feet slightly elevated and stay there while accompanied by at least one other person.
2. Remove Unnecessary Clothing
One of the challenges of doing construction work in the heat is that the clothing people use to protect themselves may make them hotter. A best practice is to wear long-sleeved shirts and pants.
However, someone experiencing a heat-stress emergency should remove all unnecessary garments, such as high-visibility vests. Additionally, taking off tight clothing helps the body breathe while transferring excess heat.
3. Use Ice and Wet Cloths to Cool
If the construction site has the necessary supplies, putting the worker in a tub full of ice and cold water is an ideal way to rapidly cool them in an emergency. Alternatively, those administering first aid should place wet clothes on the individual’s neck, head and trunk, as well as under their armpits.
4. Have the Worker Sip Water
Individuals working in the heat should consume eight ounces of water every 15-20 minutes to prevent dehydration. Uninformed parties may think it is best to have affected people drink as much as they can tolerate to get rehydrated. However, the best practice is to have them only sip water. Additionally, if the construction site has rehydration sachets or tablets, adding them to the liquid can help speed recovery.
5. Do Not Try to Diagnose the Heat Stress Condition
Unless a construction company has an on-site doctor, people should focus on providing first aid rather than trying to differentiate between the various ailments extreme heat and high-humidity environments can cause. That is especially true because of the overlap between many of them.
For example, both heat exhaustion and heatstroke occur because of an elevated body temperature. However, someone who’s confused and begins slurring their words is likely suffering from heatstroke, which is a medical emergency. The more important thing to do is to monitor the person closely to see if their condition worsens or if they do not improve after an hour. Both are signs they need professional medical help.
6. Consider the Temperature Before Using Fans
Many people consider electric fans convenient methods of cooling down during hot weather. However, a study indicated they can be less effective than expected in certain conditions.
The team discovered that fans aid sweat evaporation, which absorbs heat and carries it from the body. However, they did not meaningfully reduce the body’s core temperature in environments hotter than 95 degrees Fahrenheit. Researchers cited data regarding fans reducing heat-related cardiovascular strain in young adults, indicating this cooling method may have other advantages even if it does not lower the core temp.
AWARENESS PROMOTES BETTER RESPONSIVENESS
People who understand how extreme temperatures and high humidity affect construction workers will feel more confident when reacting to heat-stress events. That is a compelling reason to help all employees recognize when they or their colleagues may be overheated. That knowledge could prevent emergencies and keep everyone safe on the site.
SEE ALSO: ALL IN TOGETHER: THE ORIGINS OF CONSTRUCTION SAFETY WEEK
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