Wind Chill Temperature: A Guide for Employers

Outdoor workers exposed to cold, wet, windy conditions are at risk for cold stress. Both air temperature and wind speed affect how cold they feel. Remember that not everybody experiences cold conditions the same way. Some people are more sensitive to the cold than others. Their body temperature may be lower than 98.6 degrees to start off with -they are known as “cold-natured”; Others’ body temperature may be more “warm-natured” having a body temperature above 98.6 degrees. Take this into consideration when assigning work outdoors in the winter.

Windchill is the term used to describe the rate of heat loss from the human body, resulting from the combined effect of low air temperature and wind speed. The windchill temperature is a single value that takes both air temperature and wind speed into account. For example, when the air temperature is 40 degrees F, and wind speed is 35 mph, the wind chill temperature is 28 degrees F; This measurement is the actual effect of the environmental cold on exposed skin. Add moisture (rain, snow, high humidity) to the mix and it further increases the risk of cold stress illness.

Remember to watch your local weather forecasts and take measures to protect your employees working outdoors. A little preventive planning can save time, money, and suffering.

Stay Hydrated in Cold Weather

Losing excessive amounts of body fluid is not usually a hazard associated with cold weather. Most people associate dehydration with summer heat and humidity, but winter can drain the body of essential fluids for several reasons:

• In winter, people tend to go longer without water, not realizing that breathing cold/dry air causes the body to lose significant amounts of fluid.

• When we perspire in cold weather, the sweat turns into vapor and isn’t directly on the skin, so there is not the excessive perspiration that acts as a visual cue for us to drink.

• In winter, people feel approximately 40% less thirsty, even though the body needs the same amount of water all year round.

• Because we don’t feel thirsty as much as in the summer, we’re less likely to keep water handy in cold-weather months.

Dehydration is a danger to the body any time of the year. Most people don’t realize the hazards it poses to the heart. We need at least six 8-ounce glasses of water each day or we become dehydrated and have less blood volume, the heart must beat faster to keep oxygen and nutrients supplied to other vital organs.

Why is it so important to heart health that the body stay adequately hydrated? Consider these numbers: The body is 70% water. It is essential to health to maintain that level of water to regulate metabolism and stay healthy. For example, if a person weighs 100 pounds, 70 pounds of that weight should be water. If this ratio drops, the heart is deprived of fluid, and has to pump harder to get blood circulating and blood volume decreases. To preserve itself the body directs flow to the body core and organs. As a result, the blood vessels in the extremities (arms, hands, legs, and feet) stiffen up and constrict, putting the person at greater risk of frostbite and hypothermia.

There is a natural loss of fluid during the day from respiration and perspiration. If you are physically active in any way, you need to drink 32 ounces of fluid to maintain a healthy proportion of water in the body. If dressed in warm clothing, you sweat more and require even more fluid intake during the day. The combination of wearing warm clothing and high-intensity activity (exercise) leads to increased sweating and the possibility of dehydration. You may not feel thirsty in cold weather because your body chemistry impairs the brain’s ability to tell you when to hydrate.

One group of people who often become dehydrated is firefighters, because they are working strenuously in heavy layers of clothing. They must make themselves drink fluids even though they don’t feel thirsty.

To avoid dehydration in cold weather:

• Take fluids with you when you leave the house.

• If you don’t feel like drinking water, drink warm non-caffeinated drinks like tea, juice, or coffee to help the body stay hydrated.

• Drink often, even if you are not thirsty.

• Remember, certain fluids dehydrate the body. These include alcohol and carbonated or caffeinated drinks, including sports and energy drinks - avoid these.

• Monitor the color and amount of urine your body is producing. Your urine should be light yellow or clear. If it is darker, drink more water.

• Familiarize yourself with other common symptoms of dehydration including fatigue, feeling lightheaded, and irritability.

Any responsible person that does a lot of heavy manual labor and activity in the winter must keep their body hydrated. You are doing your body a great favor when you are conscious of your body’s need to stay hydrated in winter.

How to Dress for Cold Weather

On days when the air is cold, the wind is blowing, and the humidity is high or it’s raining, your clothing strategy is key to keeping you from getting a cold stress injury. Here are some tips for how to dress when the temperatures drop.

Layering lets you adjust your body’s temperature by putting on and removing items of clothing and maintaining an even comfort level as conditions or your exertion levels change. To dress for cold weather, you need three layers for maximum warmth and protection.

• Base layer: Your long underwear needs to keep your skin as dry as possible.

• Middle layer: Your fleece or puffy jacket needs to preserve as much body heat as possible.

• Outer layer: Your rain gear needs to protect you from rain and wind.

 Choosing your base/underwear layer

Warm skin starts with dry skin, so long underwear’s job is to wick perspiration away from you. Synthetic fabrics like polyesters are great at both wicking and drying. Wool is a good natural fiber option that holds its insulating abilities even when wet. Avoid cotton fabrics, as they do not retain their insulating abilities when they get wet.

Think about the fit. Wicking cannot occur in places where fabric is not touching skin, so you want a comfortably snug (not tight) fit everywhere.

Thickness or weight: Heavyweight makes sense for sub-freezing temps and low activity levels. Midweight is a good all-around choice. Lightweight is left to milder conditions.

Choosing your middle/insulating layer

This is the layer most people think about in cold conditions, so it’s not surprising that this layer’s job is to retain warmth.  Insulating materials like fleece are a good start. Make sure your jacket is a heavyweight fleece. When you are working outdoors in serious cold weather conditions, then a puffy jacket/coat should come into play. Down coats and jackets are a good standard if you are not working in wet conditions. They lose their insulating ability when they get wet. Puffy jackets/coats with synthetic fills are a better option when conditions get damp.

Insulating thickness can be tricky because you can’t rely on thickness to indicate warmth level when insulation types differ. Temperature ratings on labels are not reliable because there are too many variables (wind, rain, activity level, etc.) You can eyeball 2 jackets with identical insulation specs though and conclude that puffier equals warmer.

Full coverage: Don’t just think about jackets/coats - save some love for the legs. Keep some insulated or fleece pants with you, so your lower half can stay as warm as your top half.

Choosing your outer layer (shell coat and pants)

This is our outer line of defense. Even though it’s often referred to as “rainwear”, this layer’s job is to shield the underneath layers from snow, sleet, rain, and wind. There are 3 important attributes to consider when choosing your outer layer.

•  Precipitation protection: A wicking base layer can’t keep your skin dry if moisture is soaking you from the outside. In winter you don’t want to sacrifice any warmth to evaporation cooling. Wear a shell that is “waterproof” rather than merely “water resistant”.

• Breathable protection: Perspiration wicked by your base layer needs a way to escape. Wear a shell that is breathable, or moisture can build up inside it and soak you. You don’t need the most expensive GORE-TEX rainwear – any shell that is designated as “waterproof/breathable” should work fine.

• Windchill protection: The good news is that any shell that is “waterproof” is also “windproof”.

Shell pants- Cold, wet ankles are no fun, so be sure your boot tops are covered. If your pants don’t cover your ankles, then consider wearing a pair of gaiters.

Keeping Your Head, Hands, and Feet Warm

To prevent extremities from getting cold, cover up everywhere. The warmest options in hats, gloves, and footwear do the same thing as layers elsewhere: wick, insulate, and block rain/wind.

Hats- Wool or synthetic beanies work well, and you can rely on your shell jacket/coat’s hood for rain coverage. Full-on winter hats will have insulation inside the shell material. Make sure your headwear covers your ears. If your face is uncomfortably cold, wear a balaclava.

Gloves- Fleece gloves provide basic warmth. Insulated gloves, especially ones with waterproof/breathable shells are better. Mittens are warmer than gloves, because they share finger warmth.

Boots- with thick non-cotton socks can provide warmth when conditions are merely cold, but not wet or snowy. Waterproof boots are the next step up. Winter boots, in addition to offering traction on snow and ice, will also include insulation.

A Warmer Coat- Think of this as a twist on “cold hands, warm heart”. If your heart is warm and toasty, then it has plenty of warm blood to pump out to the hands and feet. Choose a well-insulated waterproof winter coat.

Chemical Warming Packets- Add warmth by slipping hand and foot warmers inside your gloves and socks. They come in a variety of sizes.

Additional Layering Tips for Cold Weather

Don’t wait to adjust layers: Throw on a shell at the first sign of rain or wind and remove your insulating jacket the minute you start to sweat. Staying warm and dry is easier than warming up or drying out.

Cotton is a no-no in any layer: Set aside your love of cotton flannel (or anything cotton) because it soaks up moisture and takes forever to dry out. That is a recipe for hypothermia.

Layers should play well together: Middle and outer layers need to glide on and off. When they fit too tightly over the layers beneath them, adjustments become cumbersome and you risk constricting circulation. Purchase middle and outer layers that are big enough to provide another layer (that of air) between them. This layer of air stays warm and keeps you warmer.

Taking time to make some smart decisions about your winter clothing will keep your warm and toasty and safer this winter.

Protecting Yourself from Cold Stress Illness

Workers who are exposed to extreme cold or work in cold environments may be at risk of Cold Stress. Extremely cold or wet weather is a dangerous situation that can cause occupational illness and injuries such as hypothermia, frostbite, and trench foot.

Trench Foot

Any injury to the feet resulting from prolonged exposure to wet and cold conditions that can occur at temperatures from 60 degrees or below, when the feet are constantly wet due to sweat or immersion in water.

Symptoms: Reddening of the skin, numbness, leg cramps, swelling, tingling pain, blisters and ulcers, bleeding under the skin, gangrene (foot turning grey, dark purple, or blue).

First Aid: Remove shoes/boots and wet socks; Dry feet thoroughly; Avoid walking on feet (may cause tissue damage) for 3-10 days as per doctor’s recommendations.

Frostbite

Any injury to the body that is caused by freezing, which most often affects the nose, cheeks, chin, ears, fingers, and toes.

Symptoms: Reduced blood flow to extremities (mentioned above), numbness, aching, tingling/stinging pain, bluish or pale waxy skin.

First Aid: Get into a warm area out of the weather ASAP; Unless necessary do not walk on frostbitten feet/toes; Immerse the affected area in warm (not hot) water, or warm the affected area with body heat. Do not use radiating heat from hot pad, furnace, electric heater, or fireplace for warming; Do not rub or massage the frostbitten area (may cause tissue damage).

Hypothermia

A condition in which the body uses up its stored energy and can no longer produce heat. Often occurs after prolonged exposure to cold temperatures.

Early Symptoms: Shivering, fatigue, loss of coordination, confusion/disorientation.

Late Symptoms: No shivering, blue skin, dilated pupils, slow pulse and breathing, loss of consciousness.

First Aid: Seek immediate medical attention; Move victim into a warm room/shelter; Remove wet restrictive clothing; Warm the center of the body first (chest, neck, head, groin) using blankets or skin to skin contact under loose dry layers of blankets, towels, clothing; If the victim is conscious and lucid give them warm (not hot) non-alcoholic drinks; Once body temperature has increased, keep them dry and warm in blankets including head and neck; If no pulse, begin CPR.

Preventative Protection

Watch or listen to weather forecasts and prepare for the day:

• Monitor your physical condition and that of your co-workers

• Wear appropriate clothing for the conditions (Keep warm and dry)

• Be aware that some clothing may restrict movement putting you at greater risk due to loss of circulation; Wear loose fitting layered clothing

• Protect ears, face, hands, and feet in extremely cold, wet, windy conditions

• Take breaks in warm locations (but not overheated); Limit the amount of time outside

• Carry extra socks, gloves, hats, jacket, blankets, and a thermos of warm liquid

• Include chemical hot packs in your first-aid kit

• Avoid touching cold hard objects with bare skin

How to Avoid Injuries and Illness When Temperatures Plummet

Limiting a worker’s exposure to cold can go a long way toward preventing cold stress injuries and illnesses such as frostbite, hypothermia, trench foot, and chilblains.  Three major factors to keep in mind when working outdoors are air temperature, wind, and moisture. Exposed skin is in danger of freezing within one minute when the temperature is 10 degrees and there is a wind of around 20 mph. Wet conditions greatly increase the potential for frostbite or hypothermia. Moisture on the skin and any wind can cause the body to lose heat.

Dressing properly for the cold is critical for workers.  Experts recommend using breathable layers, making sure clothing is not so tight it cuts off circulation or impedes movement.  Be aware that PPE may restrict some movements. Layering also allows workers to remove clothing if they become too warm from exertion or changing weather conditions. Layering clothing provides a worker with better insulation against the cold because the body warms trapped air between the layers. If the fabric is breathable it will keep perspiration from building up on the skin and pulling away needed body heat. Wearing a hat or hood is also recommended, to decrease the loss of body heat escaping from the head. Knitted hats that cover the ears and at least part of the face will likely keep a worker warmer than a ball cap.

Regarding footwear, experts suggest insulated, waterproof boots with good built-in traction. In extremely cold regions, it is also recommended boots be felt lined, rubber bottomed and leather-topped. Gloves should also be insulated and water resistant.

OSHA doesn’t have a defined standard on working in the cold but states that employers must protect workers from hazards in accordance with the Occupational Safety and Health Act. The following are recommendations for employers pertaining to protecting employees:

• Schedule work to be completed during the warmest part of the day

• Tell workers to use the “buddy system” (nobody works outdoors alone) so they can monitor each other

• Provide extra workers for longer, more demanding jobs

• Set up a warm dry shelter for workers to take breaks in out of the cold

• Provide warm liquids to drink, avoiding caffeine and alcohol

• Use engineering controls such radiant heaters, if possible

• Ensure you have a method to communicate with all workers, especially in remote locations

Also advise workers to avoid touching metal surfaces with bare skin, and to bring extra clothing in case they get wet. Have emergency cold weather kits available: blankets, a thermos of a hot beverage, first aid kit with chemical hot packs and a thermometer.

OSHA warns workers to avoid working to fatigue or exhaustion. Stay hydrated and drink as much water as in the summertime. You can get dehydrated even though you don’t feel like you are sweating. It is a common mistake in cold temperatures. People don’t realize heat is escaping their body and taking moisture from the body with it.

Employers must train their workers on the prevention, risks, and symptoms of cold stress. Quick daily reminders are also helpful, especially when the weather is particularly bad. Provide written information concerning the signs and symptoms of frostbite, hypothermia, trench-foot, chilblains, and angina. This information can be easily found on the internet. Employers should remind workers of the symptoms they need to be looking out for, and that it is a time when they must keep a close eye on their co-workers, and make sure everybody is doing “OK”.