After a long winter, we think of the summer heat as a welcome change and we just can’t wait to soak it in. However, working in warm weather presents its own problems, especially heat exhaustion and heat stroke.
Heat exhaustion is caused by the loss of body salt (which is essential for proper functioning of our cells) and heat stroke happens when the body overheats and can’t lower its temperature. These are not conditions to be taken lightly. A quick search on OSHA’s accident search result page shows that during 2017 and 2018 there have been 31 work related fatalities due to heat stroke alone.
Heat stress begins when the body exceeds its normal temperature. For most of us, that is somewhere between 97.7 and 99.5 degrees Fahrenheit. After reaching 100.4 degrees – give or take some decimal points depending on the individual condition – heat stress begins to affect the body. When it reaches approximately 104 degrees, there is the potential for serious damage to the brain or death.
(Learn more in Workers and Heat Stress: What You Need to Know.)
One way to protect employees from this hazard is by by reducing their work load and providing them with a well-ventilated and shaded area for frequent breaks and cool down time. However, given the work site conditions and project schedules, this is not always practical. When our work crews can't escape the warm weather, the easiest solution is to provide them with PPE that will help regulate body temperature.
Protective gear like hi-vis clothing, FR workwear, and cut resistant gloves provide essential protection against various hazards. However, they can also prevent body heat from escaping, which contributes to overheating.
If your employees have to wear coveralls while working outdoors, the coveralls should:
- Be lightweight – Lighter materials trap (and generate) less heat, allow for better freedom of movement, and have more air circulation.
- Keep in mind, however, that lighter materials might allow more sunlight to pass through, which could increase the risk of skin cancer with prolonged, long-term exposure.
- Be moisture wicking – Perspiration is our body's built-in cooling system. Perspiration removes heat from our bodies when it evaporates, so the protective clothing should allow perspiration to escape.
- Have a high albedo – That is, having the ability to reflect most of the sun’s light. Lighter colors reflect more light, while darker colors absorb more of them, which keeps the user warmer.
Generally speaking, synthetic materials such as Lycra, nylon, and polyester are lighter than cotton, wick moisture better, and have a better gram for gram UPF performance.
(Learn more about UV Risk in the Workplace.)
Specialty PPE to Combat Heat Stress
Some PPE is specifically designed to help keep the body cool. Although at first sight they can look like your run-of-the-mill vests, towels, hats, caps, and bandanas, they work in different ways and are suitable for different applications.
Moisture Wicking Clothing
This isn't exactly PPE, but it's a super-simple solution to help make hot, heavy PPE cooler and more comfortable. A light base layer that's designed to wick sweat away from the body can improve cooling and comfort, and even prevent chafing from wet clothing.
Evaporative cooling is one of the simplest, most effective effective, and least expensive ways to cool your body. The way it works, basically, is that you wet the garment with cool water. The cool water “extracts” the heat from the body (in heat transfer, the hot always moves to the cold), and then removes it from the body through evaporation.
This works as long as the garment is wet and cooler than the body. When it warms up, all you have to do is wet it again with cold water.
This method can be used indoor and outdoor. It works better when there is sufficient airflow and the ambient humidity is low to moderate. If the air is too humid or there is not enough airflow, the water in the garment won't evaporate and, therefore, won't dissipate the heat. In those situations, you will need to use a different cooling method.
Even your regular PPE will provide a cooling effect if you soak it in cold water. What makes these specially designed pieces different is their faster evaporation rate, resulting in better cooling.
Check out cooling towels, bands, bandanas and hard hat accessories here.
What to Choose
Always keep in mind that the specs provided for any PPE reflect its use in a controlled environment that is unlikely to resemble your workplace or job site. Do a hazard assessment, and use the PPE specs as a starting point when evaluating whether they will provide enough protection. Discuss your needs with the manufacturer's representatives and then use your own judgment to decide what kind of cooling gear will work best for your workers.
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