www.cos-mag.com
Nov 15, 2016

How to prevent cold stress among outdoor workers

Frostbite, hypothermia serious concerns
By Amanda Silliker

Several hundred metres off the coast of Newfoundland, 2,000 workers are building a platform for the Hebron heavy oil project before it is towed to its offshore location in 2017. Every day, crews take a ferry to and from the work site where high winds and wet environments prevail. Working in these types of conditions means cold stress is always top of mind. 

“We are constantly working around water. We are always getting winds off the ocean,” says Joe Lake, operations/safety interface lead on the Hebron project in Bull Arm, N.L. “Cold stress is very much a concern for us. It’s a constant reminder for us on our project here.”

Cold stress (lowered internal body temperature) is not just an issue among companies operating in the middle of the ocean; workers in industries all across Canada need to be aware of this hazard. It can be a problem for anyone who works outside, such as within forestry, construction, transportation, mining, utilities, emergency response and outdoor municipal work.

And it’s not just an issue in the winter, notes Lake, who is also the president of the Newfoundland and Labrador Occupational Health and Safety Association.

“Even in the summer, when you consider some of these factors, wind chill and wet clothing, things like that, cold stress starts to occur in warm seasons as well,” he says. 

The first issue that may arise when a worker is under cold stress is frost nip, which occurs when ear lobes, noses, cheeks, fingers or toes are exposed to the cold and the top layer of the skin freezes. The skin turns white and may feel numb. 

“Sometimes you don’t even feel when your face is getting cold,” says Frédéric Boucher, vice-president of consulting services at Medial OHS Consulting Services in Quebec City. “It’s usually your colleague who is going to tell you your face is white. Make sure your skin is covered first and not exposed to wind.”

The next injury that can occur is frostbite, which is the freezing of the underlying tissue. Symptoms include redness and swelling, grey or white patches, coldness, tingling and numbness. Blisters may occur in extreme cases. The areas where the blood vessels are small and close to the surface of the skin, such as the extremities, are at the highest risk. 
When a worker suffers from frostbite, his blood vessels may be severely and permanently damaged and blood circulation may stop in the affected tissue.

“There can be some ice crystals on your skin that can cause damage if you rub it. You can damage your vascularization and tissue and extremities — never rub it,” says Boucher, adding warm water should not be applied to their affected area either. “Gently warm up inside… and let your skin warm up gradually.”

The area should be loosely covered with gauze and the victim transported to a health-care facility. Thawing is best done at a hospital. 

If the worker stays in the cold too long and does not seek medical attention quickly, the damage can be permanent.
“You are going to break the blood vessels and the skin is going to turn black because there is not going to be any oxygen from the vascularization and the blood is not going to be able to get to the tissue, then it’s going to die,” says Boucher. “You can have gangrene and lose a toe or finger.”

Cold stress can eventually lead to hypothermia (abnormally low core body temperature), which is a gradual process. The first warning signs will be feeling cold, shivering, grogginess and poor judgment or confused thinking. 

“Which is why it’s a concern for us safety folks,” says Lake. “You are probably starting to make poor decisions around the work and taking risks you probably wouldn’t in your normal state.” 

At this stage, encourage the worker to stay active, bring her into a warm area and get her warm food and drink, all of which are forms of treatment, according to Workplace Safety North. Remove any wet clothing or add another layer if needed.

Moderate symptoms include: violent shivering, inability to think or pay attention, slow and shallow breathing, slurred speech and poor body co-ordination, according to WorkSafeBC. Severe symptoms are: loss of consciousness, little or no breathing and weak, irregular or non-existent pulse. If the worker is exhibiting these symptoms, call 911 immediately and move him to a warm, dry area. Remove any wet clothing and wrap the worker in warm covers. Body-to-body contact can help rewarm the victim slowly. If the victim is conscious, give her warm (but not hot), sweet drinks, such as power drinks.

“Handle the person very cautiously with no sudden movements or jerking because he already has an elevated heart rate, so you could actually bring on a heart attack. You have to treat him with a lot of care and slowly,” says Lake. 

Because hypothermia happens gradually, workers may not recognize it in themselves, so they need to look out for each other. If hypothermia is not addressed, death can occur.

“As long as you feel cold and stay outside a long time, it is going to be at the end that your respiration will be erratic, your heart will have problems with beating and providing oxygen from your blood to the upper and lower parts of the body and you will fall unconscious at one point and fall asleep and never wake up,” says Boucher.

While it’s quite rare for this to happen while working outside, it can occur if a worker falls asleep on the job or hits his head and loses consciousness, he adds. Due to all the serious hazards of working in the cold, no one should be working alone outdoors in the winter, says Chris Serratore, health and safety specialist at Workplace Safety North in Thunder Bay, Ont.   

Trench foot, or immersion foot, is another consideration when working in the cold. It’s caused by prolonged exposure to wet, damp or cold temperatures. Trench foot is certainly on the radar at the Hebron project. 

“We are working around the wet environment and a lot of times it’s very labour intensive what the workers are doing here. Some of the workers spend a lot of time with their feet in the water,” says Lake. 

Symptoms may begin within several hours up to three days. The primary injury is to nerve and muscle tissue. Symptoms include tingling and numbness; itching, pain swelling and leg cramps; and blisters or bleeding under the skin, according to the Thermal Conditions Code of Practice of the Workers’ Safety and Compensation Commission of the Northwest Territories and Nunavut (WSCC).

If a worker is suffering from trench foot, seek medical attention, remove boots and wet socks and dry the feet. 

Reduce the danger
Cold stress should be treated no differently than any other workplace hazard, says Lake. A hazard assessment needs to be the first step then controls can be put in place. 

While companies often cannot eliminate the cold work environment, they should ask questions around what really needs to happen in these conditions or what can be deferred, he says. 

Modifications can often be made to facilities and equipment, such as placing heated shelters on site. Tools can also be redesigned so workers do not need to remove their gloves to use them. 

Since there is no exposure limit for working in the cold in Canada, safety managers need to make their own procedures. They need to be aware of the outside temperature as well as the wind chill.

“As an example, if it’s -15 C outside and there’s wind, the effect of the wind on your skin or extremities will be much worse,” says Boucher. “With a 35 kilometre wind outside, it will feel more -27 C.” 

A chart developed by Work Safe Saskatchewan indicates various threshold limit values for work. For example, the chart indicates non-emergency work should cease at -43 C without wind, -40 C with wind at 8 kilometres per hour, -38 C at 16 kilometres, etc.

Lake encourages his workers to assess the temperature every day for the specific task at hand.

“Maybe it’s a half-hour today but tomorrow two hours might be acceptable,” he says. “Really, we look at it job by job, shift by shift.”

Every day, the health and safety department at the Hebron project gives out a communication on the wind chill and temperature so workers understand what the weather conditions are going to be like during their shift.

There needs to be a policy that outlines when workers need to go inside for a warm up break. Work Safe Saskatchewan’s chart outlines a suggested warm-up schedule based on temperature and wind. As an example, for a four-hour shift, if the temperature is –33 C with an 8 kilometre per hour wind, the worker needs three breaks (of 10 minutes each) and the work period should not exceed 55 minutes.

The warm up break can take place inside, in a tent, cabin, restroom or a warming shelter. A work truck or the cab of equipment may be sufficient.

Work rotation also works well, says Lake, so workers are not in cold environments for too long. 

Employers need to keep in mind there is an acclimatization process when working in the cold. According to WSCC, people need at least four to seven days to acclimatize, but it may take up to three weeks. It recommends a scheduled exposure. 

“Physiologically it takes a while for the body to adjust to those conditions, so if you sort of build it up on a gradual basis, so maybe every day you might increase the time you are spending outside by half an hour or an hour each day to the point where the body is better adjusted to those conditions,” says Serratore.

Not all workers will acclimatize the same, and each worker needs to be monitored. Those who are healthy and fit tend to adjust faster to the cold. Some medical conditions can increase susceptibility to cold, such as Raynaud’s syndrome (white finger disease) and hypertension. Workers taking insulin or anti-thyroid drugs may also be more sensitive to the cold, says WSCC.

What to wear
Personal protective equipment (PPE) is an important component when working in the cold. Clothing should be suited to the conditions (wind, rain, snow), the level and duration of activity and job design. Whatever the circumstances, layering is crucial when working in the cold. This allows workers to prevent excessive sweating by removing layers or putting them back on as conditions and activity levels change. 

“It’s just like an onion with multiple layers,” says Boucher. “Provide the appropriate clothes regarding the temperature, not too cold and not too warm.”

Workers need to start with a base layer that is right next to the body, such as long underwear. This should be made of synthetic fabric or wool to allow moisture-wicking. Cotton should not be worn.

“In the wintertime cotton is rotten. It holds moisture and it would hold it right against your skin,” says Serratore. “You feel like you’re freezing.”

A middle, insulating layer is next, which should be made of wool, quilted fibres or synthetic fleece, according to WSCC, and should be appropriately matched to the amount of activity a worker is doing.  
 
For most outdoor work in Canada, the outer layer should be windproof and waterproof. This layer should be able to close or open at the waist, neck and wrists to control how much heat is retained. The jackets should allow for ventilation, such as having zippers under the arms. When workers are taking warm-up breaks, they should remove this outer layer. 

Hard hats should be worn with an appropriate liner as well as face shield, face mask or baklava. Layering for hand protection is recommended. A thin glove that is suited to intricate tasks can be worn inside a large mitt. Workers should wear insulated gloves when working with cold surfaces.

A good pair of boots is essential for winter work. Felt-lined, rubber-bottomed, leather-topped boots with removable felt insoles are best suited for heavy work in the cold, according to WSCC. But if the work involves standing in water or slush, waterproof boots must be worn. Keep in mind that waterproof boots do not allow ventilation and will become damp quicker. 

Boots should fit comfortably — not too tight — and be insulated — but not too warm. Workers should use a two-layer sock system: a thin polypropylene sock with a wool sock over top. This allows moisture-wicking while staying warm. 

Workers need to take all this into consideration and be well prepared before working in cold temperatures because there is a higher accident rate when working outside, says Boucher.

“When you have to do complex tasks outside, your mind may not be as sharp as when you are working in an office or factory. Cold might affect concentration when performing complex mental tasks,” he says. “Also the lower temperature can affect you physically. It might affect your muscles by deeply reducing your strength and joints mobility.”

All outside workers need to have an emergency kit with them at all times — which is often overlooked, says Serratore. It should include warm clothes, food and basic emergency supplies because working in the elements means things don’t always go as planned. 

“For example, a crew... hops in their heated piece of equipment but then they have a breakdown. Now they are 5 kilometers away from their truck. I have seen it happen where guys don’t even think to bring a winter coat with them,” he says. “That’s where it would be more of an emergency situation. Now they’re cold and it’s going to be hard to get them warmed up and the severity of frostbite or the effects of the cold can become worse.”

This article originally appeared in the October/November 2016 issue of COS.