Workers who are exposed to extreme cold or work in cold 

environments may be at risk of cold stress. Extremely cold 

or wet weather is a dangerous situation that can cause 

occupational illness and injuries such as hypothermia, 

frostbite, trench foot, and chilblains.

Hypothermia

A condition in which the body uses up its stored energy and 

can no longer produce heat. Often occurs after prolonged 

exposure to cold temperature. 

Early symptoms

■ Shivering

■ Fatigue

■ Loss of coordination

■ Confusion and 

disorientation

Late symptoms

■ No shivering

■ Blue skin

■ Dilated pupils

■ Slowed pulse and breathing

■ Loss of consciousness

First Aid

■ Request immediate medical assistance.

■ Move the victim into a warm room or shelter. 

■ Remove wet clothing.

■ Warm the center of their body first—chest, neck, head, and 

groin—using an electric blanket; or use skin-to-skin contact 

under loose, dry layers of blankets, clothing, or towels.

■ If conscious, warm beverages may help increase the 

body temperature. Do not give alcohol.

■ Once temperature has increased keep them dry and wrapped 

in a warm blanket, including the head and neck.

■ If no pulse, begin CPR.

Frostbite

An injury to the body that is caused by freezing, which most 

often affects the nose, ears, cheeks, chin, fingers, or toes.

Symptoms

■ Reduced blood flow to 

hands and feet 

■ Numbness 

■ Aching

■ Tingling or stinging 

■ Bluish or pale, waxy skin

First Aid

■ Get into a warm room as soon as possible. 

■ Unless necessary, do not walk on frostbitten feet or toes. 

■ Immerse the affected area in warm (not hot) water, or 

warm the affected area using body heat. Do not use a 

heating pad, fireplace, or radiator for warming.

■ Do not massage the frostbitten area; doing so may cause 

more damage.

Fast Facts

Cold Stress

Protecting Yourself from
Trench Foot

An injury of the feet resulting from prolonged exposure to 

wet and cold conditions that can occur at temperatures as 

high as 60 °F if the feet are constantly wet.

Chilblains

Ulcers formed by damaged small blood vessels in the skin, 

caused by the repeated exposure of skin to temperatures just 

above freezing to as high as 60 °F.

Protect Yourself

■ Monitor your physical condition and that of your coworkers.

■ Wear appropriate clothing. 

ӽ Wear several layers of loose clothing for insulation.

ӽ Tight clothing reduces blood circulation to the extremities. 

■ Be aware that some clothing may restrict movement 

resulting in a hazardous situation.

■ Protect the ears, face, hands and feet in extremely cold or 

wet weather.

ӽ Boots should be waterproof and insulated.

ӽ Wear a hat to reduce the loss of body heat from your head.

■ Move into warm locations during breaks; limit the amount 

of time outside.

■ Carry extra socks, gloves, hats, jacket, blankets, a change 

of clothes and a thermos of hot liquid.

■ Include chemical hot packs in your first aid kit.

■ Avoid touching cold metal surfaces with bare skin.

Symptoms 

■ Reddening of the skin

■ Numbness

■ Leg cramps

■ Swelling

■ Tingling pain

■ Blisters or ulcers

■ Bleeding under the skin

■ Gangrene (foot may turn 

dark purple, blue, or gray)

First Aid

■ Remove shoes/boots and 

wet socks.

■ Dry feet.

■ Avoid walking on feet, 

as this may cause tissue 

damage.

Symptoms

■ Redness

■ Itching

■ Possible blistering

■ Inflammation

■ Possible ulceration in 

severe cases

First Aid

■ Avoid scratching.

■ Slowly warm the skin.

■ Use corticosteroid 

creams to relieve itching 

and swelling

■ Keep blisters and ulcers 

clean and covered.

DEPARTMENT OF HEALTH AND HUMAN SERVICES

Centers for Disease Control and Prevention

National Institute for Occupational Safety and Health

www.cdc.gov/niosh/topics/outdoor/

DHHS (NIOSH) Publication No. 2010–115

Telephone: 1–800–CDC–INFO

TTY: 1–888–232–6348

E-mail: cdcinfo@cdc.gov

safer • healthier • peopleTM