Hypothermia and Cold Stress

Hypothermia occurs when the body loses heat faster than it can produce it, dropping core temperature below 35°C.
Construction workers are at high risk during winter months, especially in exposed and elevated locations.
Wind chill dramatically increases heat loss — a 10 mph wind at 5°C feels like minus 1°C on exposed skin.
Early symptoms include shivering, confusion, slurred speech, and loss of coordination.
Severe hypothermia can cause unconsciousness, cardiac arrest, and death if untreated.
Wet clothing accelerates heat loss — workers caught in rain or working near water are especially vulnerable.
Cold stress also includes frostbite to extremities and non-freezing cold injury to hands and feet.
Workers taking certain medications or with circulatory conditions face increased risk.
Night shift workers and lone workers in remote locations are particularly exposed to cold stress.
The Management of Health and Safety at Work Regulations 1999 require employers to assess cold weather risks.

Prevent fatalities	Untreated hypothermia progresses rapidly from confusion to unconsciousness and death, particularly outdoors.
Worker fitness	Cold stress reduces manual dexterity, concentration, and reaction times, increasing the risk of accidents.
Employer duty	MHSWR 1999 requires employers to assess and control risks from cold working environments on site.

Do

Don't

Provide warm welfare facilities with hot drinks available during cold weather
Wear multiple layers of clothing including a moisture-wicking base layer
Schedule regular warm-up breaks, especially for workers in exposed locations
Monitor colleagues for early signs of hypothermia such as shivering and confusion
Change out of wet clothing as soon as possible to prevent further heat loss
Eat regular meals — the body needs energy to generate heat in cold conditions
Plan work to reduce exposure time in the coldest and most windswept areas
Ensure lone workers in remote locations have communication and check-in procedures
Provide appropriate cold weather PPE including insulated gloves and thermal hats
Call emergency services immediately if someone shows signs of severe hypothermia

DON'T ignore shivering, confusion, or slurred speech — these are warning signs
DON'T continue working in wet clothing during cold weather conditions
DON'T skip meals or rely on caffeine alone to stay warm on site
DON'T allow workers to remain in exposed elevated positions for long periods
DON'T rub or massage frostbitten skin — this causes further tissue damage
DON'T give alcohol to a person with suspected hypothermia
DON'T immerse a hypothermic casualty in hot water — rewarm them gradually
DON'T dismiss cold stress complaints as workers just being uncomfortable
DON'T send lone workers to remote locations without cold weather risk assessment
DON'T assume thermal PPE alone is sufficient without scheduled warm-up breaks

See also: Winter Working Safety | Cold Weather PPE

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