Page 27 - Occupational Health & Safety, December 2018

key to gaining buy-in and cooperation with safety standards. Lightweight, breathable, and moisture wicking are characteristics commonly talked about during the warmer months in regard to staying cool and com- fortable, but the same science can be ap- plied to keeping the body warm and com- fortable in the cold.
Maintaining comfort in winter is cen- tered on keeping the body warm. Light- weight garments may seem counterin- tuitive for protecting against the cold, but layering up lightweight garments is one of the best ways to combat the cold and re- main comfortable. The secret to layering is the air gap between layers, which pro- vides excellent insulation. This air insula- tion is also what results in most layered systems arc testing much higher than the individual garment ratings added togeth- er. Layering allows wearers to adjust their level of protection as the environmental conditions change throughout the day. Another benefit of increasing warmth by adding lightweight layers is mobility. In- stead of adding one heavy layer on top of regular daily wear, lightweight layers are less likely to have a negative impact on mobility and comfort than a bulky, heavy, outerwear garment. For workers doing light physical activity in extreme cold en- vironments, a heavy outerwear piece may make more sense. Workers in moderate to substantial physical activity jobs will benefit from this light layering principle to avoid overheating.
The Importance of Moisture Wicking
Garments that contribute to overheating can actually end up making the wearer feel colder. How is this possible? Overheating due to bulky outerwear can cause excessive sweating, leaving the garments and skin feeling damp. According to OSHA, damp- ness can quickly accelerate heat loss, drop- ping skin temperature and contributing to cold stress. (OSHA 2018) For this reason, breathable, moisture-wicking clothing is recommended in cold environments. Gar- ments that wick and breathe are less likely to contribute to overheating during physi- cal activity, thus keeping the wearer dryer for a longer period of time.
Combining light layers is important to maintaining warmth, but what you layer together matters. Garments such as 100 percent cotton are not recommended by
OSHA because they retain moisture, mak- ing them less effective at insulating and more likely to accelerate heat loss. Staying dry during colder months plays a key role in reducing the risk of cold stress and hy- pothermia. According to the CDC, “While hypothermia is most likely at very cold temperatures, it can occur even at cool tem- peratures (above 40o F) if a person becomes chilled from rain, sweat, or submersion in cold water.” (CDC, 2016) A moisture-wick- ing base layer is great for pulling moisture away from the body, but if the next layer does not have the same performance, mois- ture can either get trapped in that garment or between the layers, leaving the wearer feeling damp and uncomfortable. Combin- ing high-performance work wear for all layers allows the garments to consecutively move the moisture away from the body in order to keep wearers and their clothing dry and warm.
Moisture wicking is the process in which a fabric pulls moisture away from the skin and then pushes that moisture out to the surface of the fabric. When the layer- ing system is made up of moisture-wicking fabrics, moisture is transferred though the layers out to the surface, where it can dry quickly. This push-pull can be achieved in two ways. One is a treatment or finishing technique that can be applied to a fabric. This performance typically lasts a certain number of launderings, and effectiveness decreases with wash and wear of the gar- ment. The other way to achieve this push- pull process is to start at the fiber level and engineer a moisture-wicking fabric for per- manent performance.
Fibers that naturally absorb water eas- ily are called hydrophilic. Common water- loving fibers are cotton, wool, and rayon. Alternatively, there are some fibers that nat- urally resist or push water away. These are referred to as hydrophobic, or water-hating fibers. Modacrylic, polyester, and nylon are common hydrophobic fibers. Combining both types of fibers will result in a fabric that will absorb perspiration but then be able to release it quickly so it can evaporate. Using the right combination of hydrophilic and hydrophobic fibers can result in a fab- ric that dries three to four times faster than cotton. This fast dry process means that the wearer will stay dry and more comfort- able. In the case of winter layering, this can mean a decreased rate of heat loss.
Layering the Right Way
Remember that compliance with the ap- propriate protective standard should al- ways be included in selecting PPE, regard- less of what the weather brings. Additional layers added to a typical FR uniform also need to be FR and comply with those same standards. Topping everyday FR PPE with a garment that can’t stand up to your po- tential hazard can contribute to and exac- erbate injuries in the event of an accident. After appropriate protection against regu- lated hazards has been confirmed, be sure to consider protection against the climate, both heat stress and cold stress.
Melissa Gerhardt is the Product Manager of Arc Flash and Flame Resistant Cloth- ing at National Safety Apparel. Her back- ground in technical design and a desire to work in the U.S. apparel industry led her to National Safety Apparel seven years ago. Melissa previously managed National Safety Apparel’s Research & Development Group and was instrumental in the devel- opment and launch of innovative products such HYDROlite FR, ArcGuard Active, and Explorer Series, which was the industry’s first dual-certified outerwear line. She now uses her industry expertise and product knowledge to manage both the Arc Flash PPE and FR Clothing lines for NSA.
REFERENCES
1. Centers for Disease Control and Prevention. (2016, December). Hypothermia. Retrieved from https://www.cdc.gov/disasters/winter/stay- safe/hypothermia.html
2. Centers for Disease Control and Prevention. (2016, December). Stay Healthy in Cold Weather. Retrieved from https://www.cdc.gov/disasters/ winter/staysafe/index.html
3. Dorsey, A. R. (2018, February). Preventing Cold Stress While Working Outdoors. Retrieved from Laborers’ Health & Safety Fund of North America: https://www.lhsfna.org/index.cfm/ lifelines/february-2018/preventing-cold-stress- while-working-outdoors/
4. OSHA. (2018, September). Cold Stress Guide. Retrieved from Occupational Safety and Health Administration: https://www.osha.gov/SLTC/ emergencypreparedness/guides/cold.html
5. Princeton University. (2018, October). Princ- eton University EHS. Retrieved from Cold Stress Facts: https://ehs.princeton.edu/workplace- construction/occupational-health/heat-cold- stress/cold-stress-facts
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