What Is Hypothermia
Hypothermia occurs when core body temperature drops below 95 degrees Fahrenheit (35 degrees Celsius). At this threshold, the body loses heat faster than it can generate it, triggering a cascade of physiological failures that can become life-threatening within hours or even minutes, depending on exposure conditions and individual factors.
Workplace Hazard Recognition
OSHA doesn't have a specific hypothermia standard, but the agency enforces the General Duty Clause requiring employers to provide a workplace free from recognized hazards. Cold-related work environments fall under this requirement. Industries with high hypothermia risk include construction, utilities, emergency services, outdoor landscaping, and agriculture. Workers in these sectors face particular danger during fall and winter months when core temperatures can drop rapidly.
The three stages of hypothermia progression are critical for recognition:
- Mild (90-95°F): Shivering, confusion, loss of coordination, slurred speech. Workers often don't recognize the danger and may resist help.
- Moderate (82-90°F): Shivering stops, drowsiness intensifies, irrational behavior emerges. Heart rate and blood pressure drop significantly.
- Severe (below 82°F): Loss of consciousness, minimal vital signs, risk of cardiac arrest. Even unresponsive individuals may survive with proper rewarming.
Prevention and Controls
Effective cold exposure prevention requires a layered approach. Implement engineering controls first: enclosed work areas, heated shelters, or rotational schedules that limit continuous cold exposure. Administrative controls follow: establish work-rest ratios (typically 50 minutes work, 10 minutes warming for temperatures below 32°F), buddy systems, and mandatory break schedules. Personal protective equipment serves as the final layer, with emphasis on moisture-wicking base layers, insulated outer shells, and extremity protection.
Conduct cold stress assessments during your regular safety audits. Document wind chill calculations using the National Weather Service formula and establish exposure limits. At wind chills below negative 50°F, OSHA recommends work suspension for non-essential activities.
Emergency Response Procedures
If hypothermia is suspected, call emergency services immediately. While waiting, move the person to a warm environment carefully, avoiding jarring movements that can trigger cardiac arrhythmia. Remove wet clothing gradually and apply passive external rewarming with blankets. Avoid rubbing the skin or applying direct heat, which can cause afterdrop,a paradoxical further temperature decrease. Do not give stimulants or alcohol. Check for pulse for up to 30 seconds; if absent, begin CPR. Victims have survived extended cold exposure; aggressive rewarming should continue until the person is warm and unresponsive.
Common Questions
- How quickly can hypothermia develop? Onset depends on air temperature, wind speed, moisture, activity level, and body composition. In extreme conditions with wind chill below negative 50°F, dangerous hypothermia can develop in 10 to 30 minutes of exposure.
- Should we cancel outdoor work below a certain temperature? There's no single threshold. Instead, calculate wind chill, assess work intensity, and implement mandatory break schedules. Many facilities suspend non-essential outdoor work when wind chill reaches negative 50°F or lower.
- Can someone get hypothermia in cool weather, not just freezing? Yes. Wet conditions, wind, exhaustion, and immersion in water can produce hypothermia even at temperatures above freezing. Someone working in damp 50°F conditions is at risk if controls are inadequate.