cold stress hazards and prevention

Copyright ©2013 The Windsor Consulting Group, Inc.

Working in Cold Environments - How to Keep Workers Safe and Productive

When the Mercury Plunges

WARNING: This presentation contains photos that some viewers may find disturbing".

Overview

Workers who are exposed to extreme cold or work in cold environments may be at risk of cold stress.

Extreme cold weather is a dangerous situation for people without shelter, outdoor workers, and work areas poorly insulated or without heat.

Weather-related conditions may lead to serious health problems.


Overview

What constitutes cold stress and its effects can vary across different areas of the country.

In regions unaccustomed to winter weather, near freezing temperatures are considered factors for "cold stress."

Whenever temperatures drop decidedly below normal and as wind speed increases, heat can more rapidly leave your body.


Goals

Cold-related illnesses and injuries At-risk occupations and recreational activities Signs and symptoms of cold exposure Emergency response and first aid treatment Risk factors, evaluation of work environment,

prevention measures and protective clothing Case study and analysis Quiz


Cold Workplaces

Roofs in cold weather Bridges near large

bodies of water High-rise buildings

exposed to wind Refrigerated rooms

or containers Commercial fishing areas Steel structures that retain cold Unheated warehouses in cold climates


Cold Workplaces

Offshore oil/gas platforms Marine vessels Freezers/food warehouses Arctic exploration and

research projects Deep sea diving Logistics and transport Doormen and taxi drivers Longshoremen and stevedores Outside construction job sites


Non-Work Cold Environments

Snowmobiling and tobogganing Downhill/cross-country skiing Ice skating and dog sledding Winter hunting and ice fishing Outdoor camping, hiking, boating Snowshoeing and snowboarding Rock and mountain climbing Holiday decorating home exterior Deicing, shoveling, and snow removal Riding motorcycles and off-road vehicles


Risk Factors Related to Cold

A cold environment challenges the worker in three ways: by air temperature, air movement (wind speed), and humidity (wetness).

In order to work safely, challenges have to be counterbalanced by proper insulation (layered protective clothing), buddy system, physical activity, diet and nutrition, acclimatization, and by controlled exposure to cold (work/rest schedule).



Air Temperature: Air temperature is measured by an ordinary thermometer in degrees Celsius (°C) or degrees Fahrenheit (°F).

Wind Speed: Different types of anemometers are used to measure wind speed or air movement. Estimates of wind speed include: .

– 8 km/h (5 mph): light flag moves,

–16 km/h (10 mph): light flag fully extended,

–24 km/h (15 mph): raises newspaper sheet,

–32 km/h (20 mph): causes blowing and drifting snow.



Humidity (wetness): Water conducts heat away from the body 25 x faster then dry air.

Physical Activity: The production of body heat by physical activity (metabolic rate) is difficult to measure. Tables are used to show metabolic rates for a variety of activities. Metabolic heat production is measured in kilo calories (kcal) per hour. One kilocalorie is the amount of heat needed to raise the temperature of one kilogram of water by 1°C.



Work/rest schedule: This work schedule has been adopted by the American Conference of Governmental Industrial Hygienists (ACGIH) as Threshold Limit Values (TLVs) for cold stress.

Protective clothing: Adequate clothing is needed for work at or below 4°C. Clothing should be selected to suit the temperature, weather conditions (e.g., wind speed, rain), the level and duration of activity, and job design.



Other factors influencing cold injuries–Insulation materials and layering –Contact with metal or cryogenic liquids –Exposed skin –Vasodilation –Vasoconstriction –Previous cold injuries – frostbite and white finger syndrome

–Constricting garments



Factors influencing cold injuries–Local pressure –Cramped position –Body type –Dehydration –Women do better in cold than men (more body fat) –Higher caloric intake –Diabetes, some medications –Alcohol, caffeine, and tobacco/nicotine


Body Reacts to Cold by:

Trying to maintain core temperature of 98.6ºF

Decreasing blood flow to extremities to prevent heat loss which– Keeps internal organs warm– Increases chance of frostbite

Shivering generates heat


Heat Lost to Environment

Radiation – loss of heat due to temperature gradient below 98.6 oF

Conduction – heat transfer from sweating – water conducts heat from body 25 faster than air – Stay dry = Stay alive

Convection - wind chill is an example of heat transfer by air convection and water currents also transfers heat away from the core body

Evaporation – removal of heat by sweating mechanism or respiration


Heat Lost to Environment


Hypothermia

Body maintains a relatively stable temperature whereby heat production is balanced by heat loss (metabolism and blood circulation)

Core body temperature is 98.6 ºF or 37 ºC If outside environment gets too cold or the

body's heat production decreases, hypothermia occurs (hypo=less + thermia=temperature).

Hypothermia is a core body temperature less than 95 ºF or 35 ºC.


Hypothermia

Progressive loss of body heat Accelerated when person is

wet or damp environment Most cases occur with air

temperatures between 30ºF and 50ºF

Can occur in air temperatures with high wind/rain as high as 65ºF

Occurs in water at 72ºF regardless of currents


Risk Factors for Hypothermia

Age – cold affects the very old and young Physiology – decreased heat production,

increased heat loss, impaired thermoregulation Mental status – impaired judgment or mental

function like Alzheimer's disease Alcohol and certain drugs can dilate blood

vessels near the skin (vasodilation) and decrease capability to shiver to stay warm



Medical conditions – hormonal abnormalities (thyroid, adrenal, pituitary glands), spinal cord injury patients may not be able to shiver, person’s who suffer stroke or brain tumors may have impairments to regulate temperature, person’s with overwhelming infection or sepsis may present lowered body temperature, and people with diabetes can appear very cold

Medications increase risk of hypothermia by limiting ability to shiver



Occupational health – –Chemical skin irritants, allergens, sensitizers, corrosives, or solvents that defat or dry the skin

–Dermatitis from contact with poisonous plants –Physical agents such as ultraviolet (UV), infrared (IR) heat or electrical burns resulting in skin damage, and hand-arm segmental vibration causing Raynaud’s syndrome can increase risk

– Cryogenic liquid or gas hazards resulting in tissue damage


Signs and Symptoms of Hypothermia

As body temp drops, a person feels cold and shivering occurs

Mental function is affected Danger increases affecting thinking and reasoning, which may go unnoticed

Initial hunger and nausea gives way to apathy Confusion, lethargy, slurred speech, so-called

“umbles”, loss of consciousness, and coma


Condition Core Temperature Signs & Symptoms of Exposure

Mild Hypothermia

99º - 97ºF Normal, shivering can begin

97º - 95ºFCold sensation, goose bumps, unable to perform complex tasks with hands, shiver can be mild to severe, hands numb

Moderate Hypothermia

95º - 93ºF

Shivering, intense, muscle incoordination becomes apparent, movements slow and labored, stumbling pace, mild confusion, may appear alert. Use sobriety test, if unable to walk a 30 foot straight line, the person is hypothermic.

93º - 90ºF

Violent shivering persists, difficulty speaking, sluggish thinking, amnesia starts to appear, gross muscle movements sluggish, unable to use hands, stumbles frequently, difficulty speaking, signs of depression, withdrawn.

Severe Hypothermia

90º - 86ºFShivering stops, exposed skin blue of puffy, muscle coordination very poor, inability to walk, confusion, incoherent/irrational behavior, but may be able to maintain posture and appearance of awareness

86º - 82ºFMuscle rigidity, semiconscious, stupor, loss of awareness of others, pulse and respiration rate decrease, possible heart fibrillation

82º - 78ºFUnconscious, heart beat and respiration erractic, pulse may not be palpable

78º - 75ºFPulmonary edema, cardiac and respiratory failure,death. Death may occur before this temperature is reached.



Mild Hypothermia

Shivering and chattering teeth

Fatigue

Loss of coordination and slower to react

Confusion and disorientation

Lack of metal alertness increased risk of accidents and mistakes

Body temperature lowered to 90-95ºF


Moderate Hypothermia

Increased mental impairment and confusion Disorientation and poor decision making Inability to take precautions from the cold Slower heart rate and breathing rate Slurred speech Body temperature

drops to 82-90ºF


Severe Hypothermia

Resembles death Dilated pupils Irregular or hard-to-find pulse No shivering No detectable breathing Loss of consciousness Older workers at risk of heart attack Body temperature <82ºF


Preventing Hypothermia

Keys to preventing hypothermia are:–Layering–Staying dry

Remember acronym COLD–Keep it Clean–Avoid Overheating–Wear it Loose and in Layers–Keep it Dry


Field Management

Goals are to:–Rescue–Examine–Insulate–Rapidly transport

If untreated, hypothermia can become a true medical emergency


Field Management

Monitor deep core body temperature with ear or temporal scanning thermometer or wireless skin sensor/monitor

Use basic principles of rewarming a hypothermic victim are to conserve the heat they have and replace the body fuel they are burning up to generate that heat.

If a person is shivering, they have the ability to rewarm themselves at a rate of 2 oC/hour.


First Aid for Hypothermia

Alert their supervisor Move victim to shelter Remove wet clothing

and wrap victim in warm covers

Warm the center of their body first – chest, neck, head, and groin area using an electric blanket, if available or use skin-to-skin contact under loose, dry layers of blankets, clothing, towels, or sheets


First Aid for Hypothermia

Give warm drinks and food to increase body temperature, if conscious

Avoid alcoholic or hot/cold caffeinated beverages

Monitor breathing and core body temperature

Keep victim dry and wrapped in warm blanket including head/neck

Administer CPR and get medical help


First Aid for Mild Hypothermia

Reduce internal heat loss–Additional layers of clothes–Dry clothing and physical activity or shelter

Add caloric fuels and hot fluids–Carbohydrates 5 calories/gram quickly released–Proteins 5 calories/gram slowly released–Fats 9 calories/gram slowly released

Add external heat source–Fire or other external heat source–Body to body contact


First Aid for Severe Hypothermia

Hypothermia wrap or multiple sleeping bags – to minimize sweating and protect against air temperature, wind and water.

Add caloric fluids fuels – gelatin mix

Absorb urine from diuresis

Add heat to major arteries with heat packs, hot water bottles, and towels



Paradoxical undressing occurs during moderate to severe hypothermia, as the person becomes increasingly disoriented, confused, and combative. Victim may begin discarding their clothing, which, in turn, increases the rate of heat loss and death.

One explanation for the effect induced malfunction of the hypothalamus, the part brain regulating body temperature



Sometimes a self-protective behavior known as terminal burrowing or “hide-and-die” syndrome occurs in the final stages before death due to hypothermia.

The afflicted will enter small, enclosed spaces, such as underneath beds or behind wardrobes.

It is associated with prior stage of paradoxical undressing


Frostnip

Mildest form of a freezing cold injury Affects ear lobes, noses, cheeks, fingers, or toes

and the top layers of the skin freeze Affected area of the skin turns white and may

feel numb Top layer of skin feels hard

but the deeper tissue still feels normal (soft) and sometimes top layer of skin peels off


Frostbite

Exposure to severe cold below 28-32ºF or contact with cold objects

Affects fingers, toes, cheeks, nose, face, and ears

Tissue freezes at 30ºF Injury may cause gangrene More susceptible to future frostbite Tissue death—amputation or loss of function


Frostbite Symptoms

Sensations of coldness by reduced blood flow

Tingling, stinging, or aching sensation

Skin feels numb andcold to the touch

Skin is waxy and appears yellowish/white

Blistering, turning red, then black


Field Management of Frostbite

Monitor air temperature and wind speed using wind chill index – freezing and hypothermia

Use contact gloves to handle all equipment, insulated and chemical resistant gloves, but never use bare hands

Avoid cotton clothing that holds perspiration Keep face and ears covered and dry Keep socks clean and dry Avoid light socks and boots


First Aid for Frostbite

Get into warm room but avoid heating pad or other dry radiant heat sources – cause burns

Warm affected area slowly with body heat Do not rub or walk with frostbitten feet - may

result in more tissue damage Use warm-hot water between 98°F-104°F Apply sterile dressing to blisters Do not thaw if there is risk of re-freezing Get medical attention; and thaw at hospital


Immersion – Non-Freezing Injury

Injury to feet that are not frozen but stay wet for many days or weeks

Occurs at temps up to 10°C/60°F Injury to nerve and muscle tissue Symptoms include tingling and

numbness; itching, pain, swelling of legs, feet, or hands; or blisters may develop

Skin may be red and turn to blue or purple In severe cases, gangrene may develop


Immersion – Non-Freezing Injury

First phase: Hand or foot is cold and without pain.

Second phase: Affected limb feels burning hot and has shooting pains.

Third phase: Pale skin, bluish coloring around the nail beds and lips, weak pulse.


Immersion – First Aid

Dry the affected part immediately. Remove wet clothing and replace with dry, warm

clothing. Rewarm affected area gradually in warm air. Do not rub or massage the affected hand/foot. Elevate the affected part to reduce swelling. Protect the casualty from additional injury. Evacuate medical treatment facility as soon as

practical


Trench Foot/Hand – Non-Freezing Injury

Injury to feet/hand exposed <12 hours to wet and cold conditions

Wet feet lose heat 25 times faster than dry feet

Tissue affected below 60ºF Blood flow reduced to feet More susceptible to future frostbite Tissue death—amputation or loss of function Also known as “wet cold disease”


Trench Foot/Hand Symptoms

Cold, numb hand/feet that may progress to hot with shooting pain

Reddening of the skin Leg cramps and swelling Tingling pain and sensitivity Blisters or ulcers Bleeding under skin may

lead to gangrene


Trench Foot/Hand First Aid

Remove wet or constrictive clothing

Elevated affected limbs Cover with layers of loose,

warm, dry clothing Do not pop blisters, apply

lotions or cream, massage, or expose to extreme heat

Avoid walking and worsening the injury


Chilblains – Non-Freezing Injury

Continuous skin exposure to air temperatures just above freezing to 50ºF

Damage to capillary beds (small blood vessels)

Repeated damage can be permanent Redness and itching returns with repeated exposure Redness on cheeks, ears, fingers, and toes


Chilblains Symptoms

Redness Itching and burning

sensation Tender to touch Possible blisters Inflammation and

swelling Ulceration in severe

cases


Chilblains First Aid

Apply local warming (put bare hands over the affected area on the face, put affected hands inside the uniform under the armpits, etc.)

Do not rub or massage the affected area Apply a field dressing to lesions (sores) Have person examined by medical personnel

when the opportunity presents itself


Chilblains First Aid

Avoid scratching Slowly rewarm skin Use corticosteroid

cream to reduce itch Keep blisters and

ulcerated area clean, covered, and dry


Other Cold Related Injuries

Freezing of cornea –Caused by forcing the eyes open during strong winds without goggles

–Treatment is very controlled, rapid rewarming e.g. placing a warm hand or compress over the closed eye.

–After rewarming the eyes must be completely covered with patches for 24 - 48 hours.



Eyelashes freezing together–Put hand over eye until ice melts; open the eye

Snow blindness–Sunburn of the eyes from reflected sunlight–Wear sunglasses with side shields or tinted goggles–Eye protection from sun is the same as a cloudy or overcast day when on snow covered ground

–Snow blindness occurs during a snow storm if the cloud cover is thin



Snow blindness–Symptoms occur 8-12 hours after exposure –Eyes feel dry and irritated, then feel as if they are full of sand, moving or blinking becomes extremely painful, exposure to light hurts the eyes, eyelids may swell, eye redness, and excessive tearing

–Treatment – use cold compresses and stay in dark environment

–Do not rub eyes


Cold Stress Factors

Low temperature Cool, high winds Dampness Cold water immersion Prolonged or

repeated exposure Inadequate clothing

or protective gear No “buddy system”


Other Risk Factors

Inadequate selection or wet clothing Prescription medications or alcohol Diseases like diabetes and thyroid conditions Severe trauma Nutrition and diet Elderly, infants, and children Persons who are mentally ill Physical condition


Control Measures

Reduce exposure by applying engineering controls such as heated shelter or break areas

Apply administrative controls like work practices, standards and operating procedures including training, timing of work, policies and other rules to reduce exposure

Use personal protective equipment (PPE) Use combination of engineering/administrative

controls and personal protective equipment


Engineering Controls

Use controls like enclosures and heating systems Air heaters, radiant heaters, or contact warm plates

may be used. (heaters that emit CO gas) Provide a heated shelter for workers to do their

work for and work/warm-up break Shield work areas from drafts or winds Use thermal insulating material on equipment

(when touching metal handles, or need to sit or kneel on concrete)


Administrative Controls

Use a work/warm-up schedule. A warm shelter or vehicle should be available so workers can warm up

Allow a period of adjustment to the cold before assigning a full work schedule

Allow individuals to set their own pace and take extra work breaks when needed

Educate new or newly transferred workers on the hazards of working in a cold environment



Avoid activities that lead to heavy sweating Do as many tasks as possible indoors and reduce

timeframe people must work outdoors Work outside during the warmer hours of the day

(mid-day/early afternoon) Minimize activities that reduce blood flow like

sitting or standing for long periods of time Use a buddy system and avoid working alone Look at co-workers for signs of cold stress



If you see symptoms in a co-worker, take appropriate preventive steps

Work practices should prevent sitting or kneeling on cold, unprotected surfaces

Older workers, or those with certain medical problems, need careful about the effects of cold stress

Check with a doctor about special needs and precautions to prevent cold stress



Avoid using alcohol or drugs that may impair judgment when working in cold environment.

Hypothermia commonly occurs in association with alcohol consumption. Besides its effect on judgment, alcohol increases heat loss by dilating blood vessels and prevent shivering

Keep energy level up and prevent dehydration by consuming plenty of warm, caffeine-free, non-alcoholic drinks and high calorie food



Supervisors and workers should be trained to watch for signs of cold stress and allow workers to interrupt work when uncomfortable

Manage work schedules to allow rest periods Training should discuss engineering controls,

work practices, and protective equipment to reduce the risk of cold stress

Specialized cold training for arctic conditions Training/education included in the HASP



ACGIH has adopted guidelines developed for working outdoors in cold weather conditions

Recommended exposure times based on the wind chill factor and assume workers wear dry clothing

Work-break schedule applies to any 4-hour period with moderate or heavy activity

Warm-up breaks are 10-min. in a warm area “Normal breaks" are taken once every 2 hours



Work and Warm-up Schedule for 4-hour Shift



Estimating Wind Speed


Wind Speed (km/h) What to Look For

10 Wind felt on face; leaves rustle; wind vanes begin to move.

20Leaves and small twigs constantly moving; small flags extended.

30Dust, leaves, & loose paper lifted; large flags flap; small tree branches move.

40 Small trees begin to sway; large flags extend and flap.

50Larger tree branches moving; whistling heard in power lines; large flags extend and flap more wildly.

60Whole trees moving; resistance felt in walking against wind; large flags extend fully and flap only at the end

Source: The Weather Network “Glossary” http://www.theweathernetwork.com/glossary/windchill_formula

Wind Chill Temperatures

Combined effect of air temperature and air movement


Wind Chill Temperatures


Protective Clothing

Several layers of clothing Synthetic fibers next to

skin to whisk away sweat Water-repellent, wind-

resistant outer clothing Hats, hoods, or face covers Insulated, waterproof footgear Insulated, waterproof gloves Change clothing when wet


Protective Clothing

Wear at least three (3) layers –Outer layer that is windproof but still allows some ventilation,

–Middle layer of wool, quilted fibers, or synthetic fleece to create an insulating layer,

–Inner layer of synthetic fabric or wool to provide ventilation and allow moisture to escape

The inner or base layer should not be cotton. Cotton stays wet and speeds heat loss


Protective Clothing

Moisture evaporation and heat loss design for clothing layers

ISO 7720 and ASHRAE 55-2010 standards for the indoor environment based on air temp and relative humidity in air


Protective Clothing

With the exception of the wicking layer do not wear tight clothing.

Loose clothing allows better ventilation of heat away from the body.

Do not underestimate the wetting effects of perspiration.

Wicking and venting of the body’s sweat and heat are more important than protecting from rain or snow.


Protective Clothing


Wear mittens rather than un-insulated gloves (mittens are warmer because your fingers stay together) or use thermal insulated gloves

Wear gloves when fine manual dexterity is not required

Nylon overmitts can be easily put on and taken off if gloved hands are necessary.

Be careful about wearing gloves/scarves getting caught in moving machinery parts

Protective Clothing


Keep your head covered (up to 40 to 50% of body heat lost when the head is exposed)

Use an appropriate hardhat liner with your hard hat

Wear a facemask, gaiters, or balaclava when working in very cold conditions

Wear socks to protect your ankles and feet. Bring extra socks if moisture or sweat is likely and change socks when necessary

Protective Clothing


Use footwear that protects against cold and dampness

Footwear should be insulated and fit comfortably when socks are layered

Boots with linings are preferred as they can be taken apart to dry more easily, or new linings can be used

Wet clothing causes body to lose heat quickly since evaporation takes up a lot of heat

Protective Clothing


Wool and synthetic fabrics, on the other hand, do retain heat when wet

Dirty or greasy clothing has poor insulating properties

Clothing Type

Long underwear Wool, silk, synthetic fabric

Pants Wool, synthetic fabric

Shirts, sweaters, turtlenecks Wool, fleece, synthetic fabric

Head gear Wool, synthetic fabrics, wind barrier fabric if necessary

Gloves, mittens Loose fitting with wool or synthetic fabric liners, thermal insulated or pair of uninsulated gloves inside mittens plus windproof overmitts for very cold conditions

Socks Two pairs – light or medium inner and heavy wool or synthetic outer socks

Parka / Jacket Loose fitting, filled with down or insulating fiber, attached hood, outer layer of windproof fabric

Cold Weather Clothing


Hand Protection

Use tools and machine controls designed for gloved hand operation

Limit bare hand work to 10-20 minutes when < 60ºF

Use warm air jets, radiant heaters, contact warm plates

Use metal handles covered by thermal insulating material

Prevent contact frostbite when near metal surfaces < 20ºF


Other Protective Controls

Eat high calorie foods – carbohydrates/protein Consume warm, sweet drinks and soups Avoid coffee - a diuretic - causes water loss

increasing dehydration Avoid alcohol - a vasodilator - increases

peripheral heat loss Avoid smoking – nicotine - vasoconstrictor and

increases risk of frostbite Stay active in good physical condition


Safe Work Practices

Avoid heavy perspiration Work in the warmest

hours of the day Minimize prolonged

sitting, standing Allow time to adjust to cold Do not work alone Watch for symptoms of cold-related illness


Cold Case Study

Hazard assessment –On the ninth floor, the wind is blowing between 20 and 25 km/h (about 15 mph).

–Wind is blowing from a side that has support beams (but no walls).

–Carpenter needs to work without gloves. The work involves moderate physical activity.

–Crew has worked at this location at least 2 months.


In Red Deer, a carpenter is working outside on a -20°C in February on a building

under construction on the 9th floor. The radio reports a general wind chill of –27.

Cold Case Study

Job hazard analysis and corrective action Workers use a work/warm-up schedule of 55

minutes of work, with 3 breaks, in a 4-hour shift Breaks taken in totally enclosed/heated room Measuring/layout on the 8th floor with walls Crew checks with “buddy” in every 30 minutes Everyone is dressed appropriately – three layers Warm drinks, soup provided in the break room


Summary

Symptoms of hypothermia and frostbite First aid treatment Wind chill factor Engineering and administrative controls Protective clothing and staying dry


Quiz

1. The body responds to cold stress by shivering and _____________________________________

2. Hypothermia can occur in air temperatures as high as 65ºF. True or False

3. Describe at least three symptoms of hypothermia.

4. Describe at least one form of environmental protection for workers in the field.

5. Other risk factors of cold-related illness include: certain medication, certain diseases, age, and physical condition. True or False


Quiz (cont.)

6. Drinking coffee will help workers stay warm.True or False

7. Describe at least three symptoms of frostbite.

8. Warm up frostbitten areas by rubbing gently. True or False

9. Environmental cold stress factors include: temperature, wind, and __________________

10.Administrative controls, such as __________, can be used to protect workers from overexposure to cold conditions


Quiz Answers

1. Decreasing blood flow to the extremities

2. True, when other contributing factors are present

3. Confusion, disorientation, slow heart rate and breathing, shivering, blue lips, poor coordination, slurred speech

4. Heated shelters, windscreens, heat sources, thermal insulated tools

5. True


Quiz Answers (cont.)

6. False, coffee increases blood flow to the extremities

7. Cold sensation, tingling, aching, numbness, white skin, waxy skin

8. False, rubbing will contribute to the skin damage

9. Dampness

10. Limiting work time or taking additional breaks


Working in Cold Environments - How to Keep Workers Safe and Productive

When the Mercury Plunges


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cold stress hazards and prevention

Health & Medicine