Understanding The Dangers of Cold Stress
OUT IN THE COLD: Be aware. Be prepared.
Winter weather presents a host of serious hazards for employees who work outdoors. The National Institute for Occupational Safety and Health (NIOSH) reminds workers in cold, wet, icy, or snowy conditions to “be prepared and be aware.”
Cold temperatures and windy conditions make workers susceptible to cold stress, which occurs by driving down the skin temperature, followed by the internal body temperature. When the body is unable to warm itself, serious cold-related illnesses and injuries, permanent tissue damage, and even death may occur. Examples of cold stress include frostbite, hypothermia, chilblains, and trench foot.
- Frostbite is caused by the freezing of skin and tissues. A wind chill of -20° Fahrenheit (F) will cause frostbite in just 30 minutes. Frostbite causes a loss of feeling and a white or pale appearance in extremities, such as fingers, toes, ear lobes or the tip of the nose. It can cause permanent damage to the body, and in severe cases, can lead to amputation.
- Hypothermia is a potentially fatal condition brought on when body temperature drops to less than 95°F. When exposed to cold temperatures, your body begins to lose heat faster than it can be produced. Prolonged exposure to cold will eventually use up your body's stored energy. Warning signs include uncontrollable shivering, memory loss, disorientation, incoherence, slurred speech, and drowsiness. It’s critical to seek medical care if you suspect hypothermia; get the person into dry clothes and them wrap in a warm blanket that covers their head and neck.
- Chilblains are painful inflammations of the small blood vessels in the skin, caused by repeated skin exposure to cold, damp conditions in temperatures just above freezing. Skin ulcers, swelling, burning, and red patches may occur. This damage, redness, and itching may return with additional exposure.
- Trench foot is a non-freezing injury of the feet caused by prolonged exposure to wet and cold conditions. Wet feet lose heat faster and circulation begins to shut down, resulting in the skin tissue beginning to die. It can occur in temperatures as high as 60°F if feet are constantly wet. Injury occurs because wet feet lose heat 25 times faster than dry feet.
WIND CHILL TEMPERATURE EXPLAINED
Both air temperature and wind speed affect how cold a person feels. Wind chill describes the rate of body heat loss resulting from the combined effect of low air temperature and wind speed. For example, when the air temperature is 40°F, and the wind speed is 35mph, the wind chill temperature is 28°F; this measurement is the actual effect of the environmental cold on the exposed skin. Health conditions like hypertension and diabetes can further increase a worker’s risk of cold-related injury.
It’s always important for employers and employees to keep an eye on the weather. You should know the differences between wind chill advisories and warnings. According to the National Oceanic and Atmospheric Administration (NOAA):
A Wind Chill Advisory is issued when wind chill temperatures are potentially hazardous.
A Wind Chill Warning is issued when wind chill temperatures are life-threatening.
Dress properly – wearing appropriate clothing for the weather is extremely important to prevent cold stress. The type of fabric worn also makes a difference. Cotton loses its insulation value when it becomes wet. Wool, silk, and most synthetics, on the other hand, retain their insulation even when wet.
Multiple layers are better than a single thick garment, so workers have the option to remove a layer when sweating or add it when taking breaks. The inner layer should provide insulation and keep moisture away from the skin, to keep it dry. Synthetic fibers, such as polyesters and polypropylene, are appropriate choices.
Check job sites – including any scaffolding and ladders, before work begins. Make sure there are no snowdrifts, ice, fallen trees, or other objects and scattered debris that could delay work or inadvertently create hazards for workers. Stress the importance of fall protection under icy conditions.
Provide a warm area for breaks – trailers, tents, or other indoor areas allow workers to warm up.
PERSONAL PROTECTIVE EQUIPMENT (PPE)
OSHA advises that weather-appropriate PPE be provided to prevent cold stress. As the last level of defense, utilizing PPE can help reduce health and safety risks related to extreme temperatures.
Gloves are a critical part of cold-weather PPE, essential for protecting against frostbite. They should balance protection, flexibility and dexterity — even at very low temperatures. Gloves with EN511 winter lining are recommended for environments down to -20º F.
Fall protection PPE can be a life-saver, especially when working at height in winter. Snow and ice multiply the number of slippery surfaces in a work environment, so a fall protection system is critical for workers climbing ladders or working on rooftops.
Eye protection is also important. Anti-fog coating and UV protection should be included in all winter safety goggles. Exposure to solar radiation from bright light reflected off the snow can damage eyesight. Eyewear without anti-fog coating tends to fog up from sweating and breathing heavily during extreme heat or extreme cold, impairing workers’ eyesight.
Head and face protection are both crucial in cold weather as well. Hard hats shield against impact, rain and wind, while a knit cap or liner helps to prevent heat loss. Up to 40% of your body heat can be lost from your head! Insulated hoods are an excellent choice to protect the nose and ears.
Footwear: Trips and falls on snow and ice are common on the job in winter, which may result in broken bones, concussions, herniated discs and sprains. Employers should clear walking surfaces and spread deicer after storms. Wearing rubber over-shoes with treads that fit over your regular shoes can help decrease fall risk, as can taking short steps and walking at a slower pace so you can react quickly to changes in traction.
In addition to protecting workers in the cold, the right equipment enables worker productivity. When workers are safe and comfortable in long shifts and tough environments, they are more engaged and confident in their tasks, performing them correctly and efficiently.