Just as heat stress is a real danger during the busiest months for the construction industry, cold stress is a serious concern for anyone working outside during the winter.
As the temperatures continue to cool and winter precipitation is more likely, it’s important for those in construction to know the warning signs of cold stress.
Cold stress is the driving down of the skin temperature – and eventually the internal body temperature (core temperature). It can lead to serious health problems and may cause tissue damage or even death.
Cold stress is more likely to occur in wet or damp conditions. Those who are predisposed to health conditions such as hypertension, hypothyroidism, and diabetes are more susceptible to cold stress, as are those who are out of shape. Dressing improperly and being exhausted can both make anyone susceptible to cold stress, despite their other health conditions.
When the body is in an extremely cold environment, most of its energy is used to keep the internal core temperature warm. This means the body will shift blood from the arms and legs and outer skin towards the core (the chest and abdomen) in order to keep the core temperature regulated. However, this shift allows exposed skin and extremities to cool rapidly and increase the risk of frostbite and hypothermia. In a wet environment, trench foot is possible as well.
All about Hypothermia
Hypothermia, when body heat is lost faster than it can be replaced and the internal drops below 95 degrees Fahrenheit, most often occurs at very cold temperatures. But it can also occur at cool temperatures (40 degrees Fahrenheit) if a person is in a wet environment – either from sweat, rain, or submersion in cold water.
A worker experiencing mild hypothermia will be alert but may begin to shiver and stomp the feet in order to generate body heat. However, those with moderate to severe symptoms will stop shivering and become uncoordinated and disoriented. They may fumble with objects and become confused. Severe symptoms include the inability to walk or stand, dilated pupils, slowed pulse and breathing, and a loss of consciousness. Seek help immediately, as severe hypothermia can result in death.
If you see someone who may be suffering from hypothermia, move them to a warm, dry area and remove any wet clothes, replacing them with dry ones and covering the body (including the head and neck) with layers of blankets. Add a vapor barrier, such as a tarp or garbage back, if possible. Be sure not to cover the face.
Give the person warm, sweetened drinks if they are alert to help increase body temperature, and place warm bottles or heat packs in armpits, sides of chest, and groin.
Seek medical assistance as soon as possible – including calling 911 in an emergency.
All about Frostbite
Frosty the Snowman may have been a jolly, happy soul, but frost on a human is no joke. Frostbite is caused freezing of the skin and underlying tissue. It typically occurs in the hands, feet, arms, and legs, and occurs more quickly the colder the outside temperature. Amputation may be required in severe cases.
A person experiencing frostbite will see reddened skin that begins to develop gray or white patches, with numbness in the affected areas. The skin will feel firm or hard, and blisters may occur in extreme cases.
If you suspect you or a coworker is suffering from frostbite, follow the hypothermia protocol, as they are likely suffering from this cold stress illness as well. Loosely cover and protect the affected area from contact and never rub the area to warm it. This can cause more damage, as can breaking blisters. Do not apply water or try to rewarm the frostbitten area before seeking medical attention. If a frostbitten area is rewarmed and then exposed to more freezing cold, more tissue damage can occur. It is always safer for a frostbitten area to be treated by a medical professional.
All about Trench Foot/Immersion
Prolonged exposure to wet and cold temperatures can result in trench foot (also called immersion foot). This stress illness can occur at temperatures as high as 60 degrees Fahrenheit if the feet are constantly wet, as wet feet lose heat 25 times faster than dry feet. In order to prevent heat loss, the body will constrict the blood vessels to shut down circulation in the feet, causing the skin tissue to die due to a lack of oxygen and nutrients and the buildup of toxic products.
Symptoms of trench foot include redness of the skin, swelling, numbness, and blisters. If you suspect you or a coworker is suffering from trench foot, seek medical assistance as soon as possible. Remove the shoes and wet socks and dry the feet immediately. Do not try to pop blisters or rub the foot to warm it. It is always better to let a professional treat immersion foot.
Preventing Cold Stress
While heat stress is a common concern for most construction companies, fewer organizations may be familiar with cold stress dangers, due to the fact that many construction firms stop work during the colder months.
But for those that do work year-round in cold temperatures, there are ways to prevent or avoid cold stress. Employers should train workers on how to recognize cold stress illnesses and injuries and how to apply first aid. Workers should also be trained in engineering controls, personal protective equipment, and work practices to reduce the risk of cold stress.
Engineering controls include using radiant heaters to warm outdoor areas or shielding work areas from drafts or wind to reduce wind chill. Safe work practices may include scheduling work for the warmest part of the day and assigning tasks in pairs so that workers may monitor each other for signs of cold stress.
Employers should provide frequent breaks in extreme temperatures and allow workers to interrupt their work if they become uncomfortable or concerned. New workers or those returning after time away should gradually increase their outdoor workload in order to acclimatize themselves to the extreme temperatures.
Dressing properly is key to preventing cold stress, including the type of fabric worn. Wool, silk, and synthetic materials retain their insulation even when wet. Those working in cold temperatures should wear at least three layers of loose-fitting clothing:
- An inner layer of wool, silk, or synthetic to wick away moisture from the body;
- A middle layer of wool or synthetic to provide insulation; and
- An outer layer that provides ventilation to prevent overheating while protecting from wind and rain.
Keep extra clothing on hand in case you get wet and need to change, and drink warm, sweetened fluids to keep your internal temperature regulated.