Cold stress – it’s a deadly serious enemy of outdoor cold-weather workers. It’s also stealthy, sneaking up on you to cause injury or even death before you even know something is wrong. Those working outdoors in cold environments for extended periods are most at risk, but the effects of cold stress can take anyone down.
When should your cold stress red flags pop up? Which of your crew members are most at risk? And what are the most effective steps you can take to keep everyone safe? Let’s dig deeper to find out.
How Cold is Too Cold?
Whenever temperatures drop below normal and wind speed increases, workers are at increased risk for cold stress. Wind chill and wetness boost risk, but surprisingly, cold stress can happen in temperatures as high as 60° F.
Cold stress risk factors include:
- Wetness/dampness, dressing improperly and exhaustion
- Predisposing health conditions such as hypertension, hypothyroidism and diabetes
- Poor physical conditioning
The Mechanics of Cold Stress
The body reacts to cold stress in a logical, systematic manner. As conditions worsen, the body shifts into survival mode by redirecting warmth and blood flow to the most critical area – the body’s core. Extremities like the hands and feet are the first to suffer. Eventually, the body lowers all skin temperature and internal body temperature. The symptoms compound, and sometimes lead to serious health problems, tissue damage and even death.
Common conditions caused by cold stress include:
- Hypothermia: In order of increasing severity, symptoms start with shivering (which ends when exposure continues), loss of coordination, confusion, disorientation, inability to walk or stand, dilated pupils, slowed pulse and breathing, loss of conscious and death.
- Trench Foot: Reduced circulation and skin death in the foot, caused by prolonged exposure to wet and cold temperatures. It can occur at temperatures as high as 60°F if the feet are constantly wet. Symptoms include Redness of the skin, swelling, numbness, blisters.
- Frostbite: Freezing of the skin and underlying tissues. Frostbite typically affects the extremities, particularly the feet and hands. Amputation may be required in severe cases. Symptoms include reddened skin with gray/white patches, numbness, affected skin feels firm or hard, and skin blisters.
Shorter Shifts, Increased Productivity
Limiting exposure is key in the prevention of cold stress. The dangers only get worse as temps lower and the wind speed picks up. Protect your crew by thinking like a hockey coach: schedule shorter shifts to keep your crew fresh and productive. Planning for shorter shifts can include adjusting work schedules or rotations to the cold weather or plummeting temps. Scheduling shifts in the middle of the day allows you to take advantage of the solar heat load that accumulates on sunny days.
Cold Weather Work/Rest Schedule
A work/break schedule based on air temperature and wind speed is a smart tool for determining the number and length of work breaks needed during a shift.
How to use the work/break schedule:
- Across the top row, locate the day’s predicted wind speed.
- Down the left side, locate today’s predicted air temperature.
- Follow across and down to find the recommended work time and warm-up/break-time in a four-hour shift.
- These administrative controls will help to reduce physical demands on workers, and actually increase productivity and worker safety. When none of the above options are viable, adding relief workers can more effectively distribute workload.
Hydrate Even If You’re Not Thirsty
Dehydration is as common in winter months as it is during the summer. The reason? Cold weather tends to move body fluids from your extremities to your core, increasing your urine output and adding to dehydration.
Just because you’re not sweating as much as you would in the blazing heat of July doesn’t mean you’re not losing moisture. In fact, you can literally see it leaving your body when temps hit freezing and your breath becomes visible.
The Big Chill
There are two sets of factors that come into play when considering the causes of cold stress. The first is personal factors like exhaustion, physical conditioning, healthy circulation and pre-existing conditions like hypertension, hypothyroidism and diabetes.
The second set includes environmental factors, such as cold air temperatures, wind speed, dampness of the air and contact with cold surfaces (hence the importance of thermal work gloves, hats, balaclavas and jackets). When it’s cold, the body must work harder to maintain its temperature. Cold ambient air temperature, water and snow all draw heat from the body. High wind speeds and dampness work to accelerate heat loss.
Calculate Your Risk
The NWS (National Weather Service) Windchill Temperature (WCT) index provides a useful formula for calculating the dangers from winter winds and freezing temperatures. For example, when the air temperature is 40°F, and the wind speed is 35 mph, your exposed skin receives conditions equivalent to the air temperature being 28° F.
The windchill index:
- Calculates wind speed at an average height of five feet, typical height of an adult human face
- Incorporates heat transfer theory, heat loss from the body to its surroundings, during cold and breezy/windy days
- Lowers the calm wind threshold to 3 mph
- Uses a consistent standard for skin tissue resistance
- Assumes no impact from the sun (i.e., clear night sky)
Cold Stress + Federal Regulations
OSHA does not have any regulation focused on cold stress. Additionally, no states have adopted a cold stress standard. If there is a cold stress incident, OSHA will refer to the General Duty Clause and issue citations based on those parameters.
What's Your Plan?
Every employer with outdoor cold-weather jobsites should have a cold stress prevention plan. Supervisors should know the signs and symptoms of cold-related illnesses. as well as the proper response to cold stress. Remind all workers of cold stress risks and signs during daily or weekly safety briefings. You should also provide comprehensive cold stress training and a break area for workers with heaters and windbreaks. Remind workers to pace themselves but keep emergency supplies on hand just in case.
Other suggestions include:
- Enclose the work area.
- Remove snow and ice from heavily traveled areas such as parking lots and sidewalks.
- Schedule outdoor work in warmer months or at the warmest times of the day, and don’t schedule demanding work in extreme temps.
- Encourage your crews to wear insulated, waterproof footwear and keep a dry change of clothing nearby.
Communication – The Ultimate Protection
Take a few minutes before a shift to educate your crew on how to work smarter in cold temps. It’s a simple yet effective way to reduce risk and boost productivity. The workwear experts at Ergodyne® have created a guide for cold temperature toolbox talks:
Ergodyne® Cold Temperature Work/Rest Toolbox Talk Guide [PDF]
Understandably, workers may slow down in cold weather. But that doesn’t mean productivity has to completely freeze. A little planning, forethought and worker communication can go a long way towards keeping your crews healthy, productive and on task.
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