Posts Tagged ‘hypothermia’

OSHA’s guide to working in cold weather

Winter weather presents hazards including slippery roads/surfaces, strong winds and environmental cold. Employers must prevent illnesses, injuries, or fatalities, by controlling these hazards in workplaces impacted by winter weather.

OSHA and National Oceanic and Atmospheric Administration (NOAA) are working together on a public education effort aimed at improving the way people prepare for and respond to severe weather.

Cold stress

It is important for employers to know the wind chill temperature so that they can gauge workers’ exposure risk better and plan how to safely do the work. It is also important to monitor workers’ physical condition during tasks, especially new workers who may not be used to working in the cold, or workers returning after spending some time away from work.

The NOAA Weather Radio is a nationwide network of radio stations broadcasting continuous weather information from the nearest NWS office. It will give information when wind chill conditions reach critical thresholds. A Wind Chill Warning is issued when wind chill temperatures are life-threatening. A Wind Chill Advisory is issued when wind chill temperatures are potentially hazardous.

Who is affected by environmental cold?

Environmental cold can affect any worker exposed to cold air temperatures and puts workers at risk of cold stress. As wind speed increases, it causes the air temperature to feel even colder, increasing the risk of cold stress to exposed workers, especially those working outdoors, such as recreational workers, snow cleanup crews, construction workers, police officers and firefighters. Other workers who may be affected by exposure to environmental cold conditions include those in transit, baggage handlers, water transportation, landscaping services, and support activities for oil and gas operations.

Risk factors for cold stress include:

  • Wetness/dampness, dressing improperly and exhaustion
  • Predisposing health conditions such as hypertension, hypothyroidism and diabetes
  • Poor physical conditioning

What is cold stress?

What constitutes cold stress and its effects can vary across different areas of the country. In regions that are not used to winter weather, near freezing temperatures are considered factors for “cold stress.” Increased wind speed also causes heat to leave the body more rapidly (wind chill effect). Wetness or dampness, even from body sweat, also facilitates heat loss from the body. Cold stress occurs by driving down the skin temperature, and eventually the internal body temperature. When the body is unable to warm itself, serious cold-related illnesses and injuries may occur, and permanent tissue damage and death may result. Types of cold stress include: trench foot, frostbite and hypothermia.

For more information, see OSHA’s Cold Stress Safety and Health Guide.

Types of Cold Stress

Immersion/Trench Foot

Trench foot is a non-freezing injury of the feet caused by prolonged exposure to wet and cold conditions. 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.

What are they symptoms of trench foot?

Reddening skin, tingling, pain, swelling, leg cramps, numbness and blisters.

First Aid

  • Call 911 immediately in an emergency; otherwise seek medical assistance as soon as possible.
  • Remove wet shoes/boots and wet socks.
  • Dry the feet and avoid working on them.
  • Keep affected feet elevated and avoid walking. Get medical attention.

Frostbite

Frostbite is caused by the freezing of the skin and tissues. Frostbite can cause permanent damage to the body, and in severe cases can lead to amputation. The risk of frostbite is increased in people with reduced blood circulation and among people who are not dressed properly for extremely cold temperatures.

What are the symptoms of frostbite?

Reddened skin develops gray/white patches in the fingers, toes, nose, or ear lobes; tingling, aching, a loss of feeling, firm/hard, and blisters may occur in the affected areas.

First Aid

  • Follow the recommendations described below for hypothermia.
  • Protect the frostbitten area, e.g., by wrapping loosely in a dry cloth and protect the area from contact until medical help arrives.
  • DO NOT rub the affected area, because rubbing causes damage to the skin and tissue.
  • Do not apply snow or water. Do not break blisters.
  • DO NOT try to re-warm the frostbitten area before getting medical help, for example, do not use heating pads or place in warm water. If a frostbitten area is rewarmed and gets frozen again, more tissue damage will occur. It is safer for the frostbitten area to be rewarmed by medical professionals.
  • Give warm sweetened drinks if alert (no alcohol).

Hypothermia

Hypothermia occurs when the normal body temperature (98.6°F) drops to less than 95°F. Exposure to cold temperatures causes the body to lose heat faster than it can be produced. Prolonged exposure to cold will eventually use up the body’s stored energy. The result is hypothermia, or abnormally low body temperature. Hypothermia is most likely at very cold temperatures, but it can occur even at cool temperatures (above 40°F) if a person becomes chilled from rain, sweat, or immersion in cold water.

What are the symptoms of hypothermia?

An important mild symptom of hypothermia is uncontrollable shivering, which should not be ignored. Although shivering indicates that the body is losing heat, it also helps the body to rewarm itself. Moderate to severe symptoms of hypothermia are loss of coordination, confusion, slurred speech, heart rate/breathing slow, unconsciousness and possibly death. Body temperature that is too low affects the brain, making the victim unable to think clearly or move well. This makes hypothermia particularly dangerous because a person may not know what is happening and won’t be able to do anything about it.

First Aid

  • Call 911 immediately in an emergency.
  • Move the worker to a warm, dry area.
  • Remove any wet clothing and replace with dry clothing. Wrap the entire body (including the head and neck) in layers of blankets; and with a vapor barrier (e.g. tarp, garbage bag) Do not cover the face.

If medical help is more than 30 minutes away:

  • Give warm sweetened drinks if alert (no alcohol), to help increase the body temperature. Never try to give a drink to an unconscious person.
  • Place warm bottles or hot packs in armpits, sides of chest, and groin. Call 911 for additional rewarming instructions.

Basic Life Support (when necessary)

Co-workers trained in cardiopulmonary resuscitation (CPR) may help a person suffering from hypothermia who has no pulse or is not breathing:

  • Call 911 for emergency medical assistance immediately.
  • Treat the worker as per instructions for hypothermia, but be very careful and do not try to give an unconscious person fluids.
  • Check him/her for signs of breathing and for a pulse. Check for 60 seconds.
  • If after 60 seconds the affected worker is not breathing and does not have a pulse, trained workers may start rescue breaths for 3 minutes.
  • Recheck for breathing and pulse, check for 60 seconds.
  • If the worker is still not breathing and has no pulse, continue rescue breathing.
  • Only start chest compressions per the direction of the 911 operator or emergency medical services*
  • Reassess patient’s physical status periodically.

*Chest compressions are recommended only if the patient will not receive medical care within 3 hours.

Wind Chill Temperature

Outdoor workers exposed to cold and windy conditions are at risk of cold stress, both air temperature and wind speed affect how cold they feel. “Wind chill” is the term used to describe the rate of heat loss from the human body, resulting from the combined effect of low air temperature, and wind speed. The wind chill temperature is a single value that takes both air temperature and wind speed into account. 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.

National Weather Service (NWS) Wind Chill Calculator: With this tool, one may input the air temperature and wind speed, and it will calculate the wind chill temperature.

The American Conference of Governmental Industrial Hygienists (ACGIH) developed the following Work/Warm-up Schedule for a 4-hour shift that takes both air temperature and wind speed into account to provide recommendations on scheduling work breaks and ceasing non-emergency work.

Dressing Properly for the Cold

Dressing properly is extremely important to preventing cold stress. When cold environments or temperatures cannot be avoided, the following would help protect workers from cold stress:

  • Wear at least three layers of loose-fitting clothing. Layering provides better insulation.
    • An inner layer of wool, silk or synthetic (polypropylene) to keep moisture away from the body. Thermal wear, wool, silk or polypropylene, inner layers of clothing that will hold more body heat than cotton.
    • A middle layer of wool or synthetic to provide insulation even when wet.
    • An outer wind and rain protection layer that allows some ventilation to prevent overheating.
  • Tight clothing reduces blood circulation. Warm blood needs to be circulated to the extremities. Insulated coat/jacket (water resistant if necessary)
  • Knit mask to cover face and mouth (if needed)
  • Hat that will cover your ears as well. A hat will help keep your whole body warmer. Hats reduce the amount of body heat that escapes from your head.
  • Insulated gloves (water resistant if necessary), to protect the hands
  • Insulated and waterproof boots to protect the feet

Safety tips for workers

  • Your employer should ensure that you know the symptoms of cold stress
  • Monitor your physical condition and that of your coworkers
  • Dress appropriately for the cold
  • Stay dry in the cold because moisture or dampness, e.g. from sweating, can increase the rate of heat loss from the body
  • Keep extra clothing (including underwear) handy in case you get wet and need to change
  • Drink warm sweetened fluids (no alcohol)
  • Use proper engineering controls, safe work practices, and personal protective equipment (PPE) provided by your employer

Winter driving

Although employers cannot control roadway conditions, they can promote safe driving behavior by ensuring workers recognize the hazards of winter weather driving, for example, driving on snow/ice covered roads; are properly trained for driving in winter weather conditions; and are licensed (as applicable) for the vehicles they operate. For information about driving safely during the winter, visit OSHA’s Safe Winter Driving page.

Employers should set and enforce driver safety policies. Employers should also implement an effective maintenance program for all vehicles and mechanized equipment that workers are required to operate. Crashes can be avoided. Learn more at the Motor Vehicle Safety (OSHA Safety and Health Topics Page) .

Employers should ensure properly trained workers inspect the following vehicle systems to determine if they are working properly:

  • Brakes: Brakes should provide even and balanced braking. Also check that brake fluid is at the proper level.
  • Cooling system: Ensure a proper mixture of 50/50 antifreeze and water in the cooling system at the proper level.
  • Electrical system: Check the ignition system and make sure that the battery is fully charged and that the connections are clean. Check that the alternator belt is in good condition with proper tension.
  • Engine: Inspect all engine systems.
  • Exhaust system: Check exhaust for leaks and that all clamps and hangers are snug.
  • Tires: Check for proper tread depth and no signs of damage or uneven wear. Check for proper tire inflation.
  • Oil: Check that oil is at proper level.
  • Visibility systems: Inspect all exterior lights, defrosters (windshield and rear window), and wipers. Install winter windshield wipers.

An emergency kit with the following items is recommended in vehicles:

  • Cell phone or two-way radio
  • Windshield ice scraper
  • Snow brush
  • Flashlight with extra batteries
  • Shovel
  • Tow chain
  • Traction aids (bag of sand or cat litter)
  • Emergency flares
  • Jumper cables
  • Snacks
  • Water
  • Road maps
  • Blankets, change of clothes

Preventing slips on snow and ice

To prevent slips, trips, and falls, employers should clear snow and ice from walking surfaces, and spread deicer as quickly as possible after a winter storm. When walking on snow or ice is unavoidable workers should be trained to:

  • Wear footwear that has good traction and insulation (e.g. insulated and water-resistant boots or rubber over-shoes with good rubber treads)
  • Take short steps and walk at a slower pace to react quickly to changes in traction

OSHA’s Cold Stress Guide

Anyone working in a cold environment may be at risk of cold stress. Some workers may be required to work outdoors in cold environments and for extended periods, for example, snow cleanup crews, sanitation workers, police officers and emergency response and recovery personnel, like firefighters, and emergency medical technicians. Cold stress can be encountered in these types of work environment. The following frequently asked questions will help workers understand what cold stress is, how it may affect their health and safety, and how it can be prevented.

How cold is too cold?

What constitutes extreme cold and its effects can vary across different areas of the country. In regions that are not used to winter weather, near freezing temperatures are considered “extreme cold.” A cold environment forces the body to work harder to maintain its temperature. Whenever temperatures drop below normal and wind speed increases, heat can leave your body more rapidly.

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.

Cold stress occurs by driving down the skin temperature and eventually the internal body temperature (core temperature). This may lead to serious health problems, and may cause tissue damage, and possibly death.

What are the risk factors that contribute to cold stress?

Some of the risk factors that contribute to cold stress are:

  • Wetness/dampness, dressing improperly, and exhaustion
  • Predisposing health conditions such as hypertension, hypothyroidism, and diabetes
  • Poor physical conditioning

How does the body react to cold conditions?

In a cold environment, most of the body’s energy is used to keep the internal core temperature warm. Over time, the body will begin to shift blood flow from the extremities (hands, feet, arms, and legs) and outer skin to the core (chest and abdomen). This shift allows the exposed skin and the extremities to cool rapidly and increases the risk of frostbite and hypothermia. Combine this scenario with exposure to a wet environment, and trench foot may also be a problem.

What are the most common cold induced illnesses/injuries?

  • Hypothermia
  • Frostbite
  • Trench Foot

What is hypothermia?

Hypothermia occurs when body heat is lost faster than it can be replaced and the normal body temperature (98.6°F) drops to less than 95°F.  Hypothermia is most likely at very cold temperatures, but it can occur even at cool temperatures (above 40°F), if a person becomes chilled from rain, sweat, or submersion in cold water.

What are the symptoms of hypothermia?

  • Mild symptoms:
    • An exposed worker is alert.
    • He or she may begin to shiver and stomp the feet in order to generate heat.
  • Moderate to Severe symptoms:
    • As the body temperature continues to fall, symptoms will worsen and shivering will stop.
    • The worker may lose coordination and fumble with items in the hand, become confused and disoriented
    • He or she may be unable to walk or stand, pupils become dilated, pulse and breathing become slowed, and loss of consciousness can occur. A person could die if help is not received immediately.

What can be done for a person suffering from hypothermia?

  • Call 911 immediately in an emergency; otherwise seek medical assistance as soon as possible.
  • Move the person to a warm, dry area.
  • Remove wet clothes and replace with dry clothes, cover the body (including the head and neck) with layers of blankets; and with a vapor barrier (e.g. tarp, garbage bag). Do not cover the face.
  • If medical help is more than 30 minutes away:
    • Give warm sweetened drinks if alert (no alcohol), to help increase the body temperature. Never try to give a drink to an unconscious person.
    • Place warm bottles or hot packs in armpits, sides of chest, and groin. Call 911 for additional rewarming instructions.
  • If a person is not breathing or has no pulse:
    • Call 911 for emergency medical assistance immediately.
    • Treat the worker as per instructions for hypothermia, but be very careful and do not try to give an unconscious person fluids.
    • Check him/her for signs of breathing and for a pulse. Check for 60 seconds.
    • If after 60 seconds the affected worker is not breathing and does not have a pulse, trained workers may start rescue breaths for 3 minutes.
    • Recheck for breathing and pulse, check for 60 seconds.
    • If the worker is still not breathing and has no pulse, continue rescue breathing.
    • Only start chest compressions per the direction of the 911 operator or emergency medical services*
    • Reassess patient’s physical status periodically.

*Chest compression are recommended only if the patient will not receive medical care within 3 hours.

What is frostbite?

Frostbite is an injury to the body that is caused by freezing of the skin and underlying tissues. The lower the temperature, the more quickly frostbite will occur. Frostbite typically affects the extremities, particularly the feet and hands. Amputation may be required in severe cases.

What are the symptoms of frostbite?

  • Reddened skin develops gray/white patches.
  • Numbness in the affected part.
  • Feels firm or hard.
  • Blisters may occur in the affected part, in severe cases.

What can be done for a person suffering from frostbite?

  • Follow the recommendations described above for hypothermia.
  • Do not rub the affected area to warm it because this action can cause more damage.
  • Do not apply snow/water. Do not break blisters.
  • Loosely cover and protect the area from contact.
  • Do not try to rewarm the frostbitten area before getting medical help; for example, do not place in warm water. If a frostbitten area is rewarmed and gets frozen again, more tissue damage will occur. It is safer for the frostbitten area to be rewarmed by medical professionals.
  • Give warm sweetened drinks, if the person is alert. Avoid drinks with alcohol.

What is immersion/trench foot?

Trench Foot or immersion foot is 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. Non-freezing injury occurs because wet feet lose heat 25-times faster than dry feet. To prevent heat loss, the body constricts the blood vessels to shut down circulation in the feet. The skin tissue begins to die because of a lack of oxygen and nutrients and due to the buildup of toxic products.

What are the symptoms of trench foot?

  • Redness of the skin, swelling, numbness, blisters

What can be done for a person suffering from immersion foot?

  • Call 911 immediately in an emergency; otherwise seek medical assistance as soon as possible.
  • Remove the shoes, or boots, and wet socks.
  • Dry the feet.

How can cold stress be prevented?

Although OSHA does not have a specific standard that covers working in cold environments, employers have a responsibility to provide workers with employment and a place of employment which are free from recognized hazards, including cold stress, which are causing or are likely to cause death or serious physical harm to them (Section 5(a)(1) of the Occupational Safety and Health Act of 1970). Employers should, therefore, train workers on the hazards of the job and safety measures to use, such as engineering controls and safe work practices, that will protect workers’ safety and health.

Employers should train workers on how to prevent and recognize cold stress illnesses and injuries and how to apply first aid treatment. Workers should be trained on the appropriate engineering controls, personal protective equipment and work practices to reduce the risk of cold stress.

Employers should provide engineering controls. For example, radiant heaters may be used to warm workers in outdoor security stations. If possible, shield work areas from drafts or wind to reduce wind chill.

Employers should use safe work practices. For example, it is easy to become dehydrated in cold weather. Employers therefore, can provide plenty of warm sweetened liquids to workers.  Avoid alcoholic drinks. If possible, employers can schedule heavy work during the warmer part of the day. Employers can assign workers to tasks in pairs (buddy system), so that they can monitor each other for signs of cold stress. Workers can be allowed to interrupt their work, if they are extremely uncomfortable. Employers should give workers frequent breaks in warm areas. Acclimatize new workers and those returning after time away from work, by gradually increasing their workload, and allowing more frequent breaks in warm areas, as they build up a tolerance for working in the cold environment. Safety measures, such as these, should be incorporated into the relevant health and safety plan for the workplace.

Dressing properly is extremely important to preventing 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. The following are recommendations for working in cold environments:

  • Wear at least three layers of loose fitting clothing. Layering provides better insulation. Do not wear tight fitting clothing.
    • An inner layer of wool, silk or synthetic to keep moisture away from the body.
    • A middle layer of wool or synthetic to provide insulation even when wet.
    • An outer wind and rain protection layer that allows some ventilation to prevent overheating.
  • Wear a hat or hood to help keep your whole body warmer. Hats reduce the amount of body heat that escapes from your head.
  • Use a knit mask to cover the face and mouth (if needed).
  • Use insulated gloves to protect the hands (water resistant if necessary).
  • Wear insulated and waterproof boots (or other footwear).

Safety Tips for Workers

  • Your employer should ensure that you know the symptoms of cold stress.
  • Monitor your physical condition and that of your coworkers.
  • Dress properly for the cold.
  • Stay dry in the cold because moisture or dampness, e.g. from sweating, can increase the rate of heat loss from the body.
  • Keep extra clothing (including underwear) handy in case you get wet and need to change.
  • Drink warm sweetened fluids (no alcohol).
  • Use proper engineering controls, safe work practices, and personal protective equipment (PPE) provided by your employer.

Additional Resources

Cold Stress. National Institute for Occupational Safety and Health (NIOSH).


NOTE:

The Occupational Safety and Health Act (OSH Act) requires employers to comply with hazard-specific safety and health standards. In addition, pursuant to Section 5(a)(1) of the OSH Act, employers must provide their employees with a workplace free from recognized hazards likely to cause death or serious physical harm. Emergency Preparedness Guides do not and cannot enlarge or diminish an employer’s obligations under the OSH Act.

Emergency Preparedness Guides are based on presently available information, as well as current occupational safety and health provisions and standards. The procedures and practices discussed in Emergency Preparedness Guides may need to be modified when additional, relevant information becomes available or when OSH Act standards are promulgated or modified.