Solution Summary: Cold Stress Prevention Program
Administrative controls, such as a cold stress prevention program, can reduce the risk of injuries associated with working in a cold environment. Working in cold temperatures and high winds for an extended period can result in cold-related injuries, particularly if the skin is wet. Implementing a comprehensive cold stress prevention program can have a positive impact on safety and productivity. Ensuring adequate maintenance of walking and working surfaces, hydration, clothing and equipment, and warming are part of a cold stress prevention program and help to lower risks for cold-related injuries.
The following information was derived from multiple sources including the American Conference of Governmental Industrial Hygienists (ACGIH) 2013 TLVs and BEIs, the Occupational Health and Safety Administration’s (OSHA) Cold Stress Guide, OSHA’s web page on Winter Weather, and the United States Army Corps of Engineers Safety and Health Requirements Manual (EM 385-1-1).
A cold stress prevention program should include:
1) the name of the individual who will be responsible for ensuring the program is in place (e.g., supervisor, foreman, safety coordinator, crew leader, etc.),
2) information on cold-related hazards and the workers at risk,
3) methods to protect workers and the resources required (e.g. warm clothing, hand and foot warmers, salt, ice melt products, access to warming areas, etc.),
4) training for workers and supervisors on how to identify, prevent, and respond to cold-related injuries,
5) monitoring workers for sign and symptoms of cold-related injuries, and
6) plans for aiding workers suffering from cold-related injuries, including emergency preparations for possible frostbite and hypothermia cases.
Specific actions to be taken before work begins:
- Check the extended weather forecast. Call or visit the National Weather Service at http://www.weather.gov/ to plan for upcoming work and prior to the start of each workday to ensure that adequate plans are in place to protect workers. You can also receive weather alerts on your cell phone or computer through http://weather.weatherbug.com/?stick=1 or the National Weather Service at http://www.erh.noaa.gov/er/iln/WEA/wireless_emergency_alert.php.
- Conduct worker and supervisor training on how to prevent and identify cold-related injuries, and provide regular reminders.
- If possible, schedule work activities during warmer times of the day and heat the work area.
- Make sure all workers know where to go for warmth. Locate warming areas for breaks as close as practical to where the work is being performed.
- Ensure that an emergency response plan is in place and identifies who knows first-aid, who will respond, who will stay with the injured person, steps for handling a worker with a cold-related injury, a map of the site, directions for emergency medical services, and how to address potential language barriers. Hypothermia, a core body temperature of less than 95°F, can pose an imminent threat to life and health, so on remote or difficult to access construction sites the plan should address air evacuation or rapid ambulance access.
Specific actions to be completed during work:
- Identify the quantity of sweet, warm, non-caffeinated liquids and the number of disposable cups that will be needed for the shift. Remind workers to drink warm liquids to stay hydrated and keep their core body temperatures up.
- Increase the frequency of rest breaks in warming shelters shielded from environmental conditions.
- Avoid fuel burning heaters, commonly referred to as “salamanders” if at all possible because of potentially deadly carbon monoxide build-up, particularly in enclosed spaces. If unavoidable, use small, inexpensive personal carbon monoxide monitors or area sampling to ensure workers are not being put at risk for carbon monoxide poisoning. Steps to control exposure are important because the gas is invisible, odorless and tasteless.
- Encourage workers to wear multiple layers of warm, breathable clothing and a wind proof outer layer.
- Keep a thermometer on the job, check it hourly and take preventive measures if there are unexpected changes in temperature and weather conditions.
- Maintain working and walking surfaces free of snow and ice by shoveling and applying sand, salt, and ice melt products. A variety of salt and ice melt products are available must be selected based on the temperature and intended use.
- Cover metal handles of tools with thermal insulating materials at temperatures below 30.2°F.
- If air temperature is 0°F or less, protect the hands with mittens and purchase tools designed to be used without taking off mittens.
- Supply eye protection for outdoor work in snow and ice-covered terrain to guard against ultraviolet light, glare and blowing ice crystals.
- Reduce the cooling effect of the wind with an engineering control as simple as a shield blocking the wind or by wearing an easily removable windbreak garment.
- Take special precautions to prevent soaking of clothes by liquids like gasoline, alcohol or cleaning fluids because of the increased risks of rapid cooling from evaporation.
- If heavy work is anticipated in the cold, ensure outer garments allow for easy ventilation to prevent wetting of inner layers by sweat.
- Provide special hand protection to maintain dexterity and prevent accidents. Below 60.8°F, special provisions for keeping hands warm must be provided if fine work will be done with bare hands for more than 10 to 20 minutes.
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Cold-related injuries are caused by working in low temperatures and high winds, particularly when the skin is wet. Outdoor workers suffer from cold-related injuries each year.
The traction between walking and working surfaces and workers' footwear is reduced when the surface is covered with ice or snow. Reduced traction makes walking and working surfaces slipperier and falls more likley. Research has shown that the rate of injuries resulting from slips and falls increases as the temperature falls below freezing (Bell, 2000 and Hassi, 2000).
The human body’s natural reaction when exposed to cold environments is to maintain its core temperature. To do so, blood shifts away from less critical body parts including the hands, feet, arms, legs and skin to concentrate in the vital chest and abdomen regions. As a result of the blood shift, the body parts containing less blood face an increased risk of cold-related injuries such as hypothermia (a core body temperature of less than 95°F) and frostbite (frozen skin or tissue). If moisture is introduced in addition to cold temperatures, trench foot also becomes a possibility (OSHA).
“Wind chill is the temperature your body feels when air temperature and wind speed are combined. For example, when the air temperature is 40°F, and the wind speed is 35 mph, the effect on the exposed skin is as if the air temperature was 28°F” (OSHA).
Cold Stress is the result of the skin temperature being lowered, ultimately resulting in a reduced core body temperature. Serious health concerns including possible tissue damage and death may occur if the situation is severe (OSHA).
The American Conference of Governmental Industrial Hygienists (ACGIH) Threshold Limit Values (TLVs) for cold stress are based on air temperature and wind speed. The TLVs specify the minimum number of warming breaks in a four-hour shift and the maximum duration of work between warming for different air temperature and wind speed combinations. The TLVs are for workers performing moderate to heavy work in dry clothing appropriate for winter work. For example, during a four hour shift at -22°F with a wind speed of 10 miles per hour, a worker should not work longer than 55 minutes before taking a 10 minute break in a warm location. This worker should take a total of three breaks in this four-hour shift. The TLVs are presented in Table 3 of the Cold Stress section of the TLV Book and displayed below. The TLV Book goes into great detail about cold stress prevention, measurement and control. It can be purchased at: http://www.acgih.org/store/.
In addition to TLVs for cold stress, the ACGIH also developed a wind chill chart. Wind chill is described as the air temperature that would feel the same on exposed human flesh as the given combination of air temperature and wind speed (CCOHS, 2008). ACGIH’s wind chill chart is Table 2 in the Cold Stress section of the TLV Book and displayed below.
With permission from ACGIH®: 2013 TLVs® and BEIs® Threshold Limit Values for Chemical Substances and Physical Agents and Biological Exposure Indices. Cincinnati, Ohio: ACGIH, 2013, p. 199.
How Risks are Reduced:
Cold stress and the risk of cold-related injury are reduced by increasing management and worker awareness of the hazards and ensuring that proper clothing and equipment available and use, heating devices are utilized and more frequent rest periods where workers can warm up are provided. Workers should wear multiple layers of warm, thermal insulated clothing and leave very little skin exposed.
The Occupational Safety and Health Administration (OSHA), National Institute for Occupational Safety and Health (NIOSH), Center for Disease Control (CDC), the American Conference of Government Industrial Hygienists (ACGIH) and industry and employee groups acknowledge the hazards associated with exposure to low temperatures and wind. The ability to reduce cold-related injuries by taking precautions such as wearing warm clothing, utilizing heating devices and breaks for warming up have been documented in government publications and by the research and medical communities.
Effects on Productivity:
Working in a cold environment has been shown to reduce productivity in construction. A comprehensive cold stress prevention program that ensures the use of protective clothing and equipment, warming breaks, and the maintenance of walking surfaces will reduce the risk of cold-related injuries and illnesses and provide greater productivity when working in a cold environment.
Engineering controls are always superior to administrative controls, such as a cold stress prevention program, and personal protective equipment, such as gloves and clothing. Engineering solutions to consider include shelters to protect workers from environmental conditions and portable electric fan heaters to warm the work or break area. Whenever possible, shelters with electric heaters inside should be used for warm up breaks when permanent heated structures are not available. Heated vehicle cabs may also be used in place of heated shelters.
Taylor Kingston and Michael R. Cooper - Aria Environmental, Inc.
Bruce Lippy - CPWR
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To obtain information, visit Staying Warm: How to Layer Clothes in Cold Weather