Cold Stress First Aid: Hypothermia, Frostbite and Trench Foot

Hypothermia is when your core body temperature drops below 95°F, and it's the cold injury that kills. Frostbite is skin and tissue actually freezing. Trench foot is a non-freezing injury from feet staying wet and cold. For all three, the first move is the same: get the worker into a warm room or vehicle, get wet clothes off, and get medical help. Then treat the specific injury. Don't rub frostbite, and don't rewarm it in the field if there's any chance it will freeze again. For hypothermia, warm the core first, not the hands and feet. Those steps come from OSHA Cold Stress, which lists support activities for oil and gas operations among the jobs exposed to cold.

Hypothermia vs. frostbite vs. trench foot

All of the signs above are from OSHA Cold Stress. The table matters because the injuries often come together. A hand on a frozen valve wheel can be frostbitten while the whole body is sliding into hypothermia. Treat the hypothermia first.

Hypothermia first aid

Shivering is the warning to act on. OSHA calls uncontrollable shivering an important mild symptom that shouldn't be ignored. Once a worker gets confused or clumsy, they often can't tell they're in trouble, so the person next to them has to make the call (OSHA Cold Stress).

1. Call 911 in an emergency.
2. Move the worker to a warm room or a running, heated vehicle.
3. Take off wet clothing and put on dry clothing.
4. Wrap the whole body, including the head and neck, in layers of blankets plus a vapor barrier such as a tarp or a trash bag. Don't cover the face.
5. If the worker is alert, give warm, sweet drinks. No alcohol, and never give a drink to someone who isn't conscious.
6. Put warm bottles or hot packs in the armpits, on the sides of the chest and at the groin. Call 911 for more rewarming instructions.
7. If there's no pulse, start CPR and keep it going until the person responds or medical help takes over.

Those steps follow OSHA Cold Stress. If your crew hasn't practiced CPR lately, our CPR certification guide covers classes and renewal.

Frostbite first aid

OSHA says to get the worker into a warm room as soon as possible and treat any hypothermia first. Then protect the frostbitten area (OSHA Cold Stress):

• Don't walk on frostbitten feet or toes unless you have to.
• Wrap it loosely in a dry cloth and keep anything from pressing on it until medical help arrives.
• Don't rub or massage it. Rubbing damages the skin and tissue.
• Don't rewarm it before medical help. No heating pads, no warm water. If a frostbitten area thaws and then freezes again, the damage gets worse. OSHA says it's safer to let medical professionals rewarm it.

On a lease that's an hour from town, that last point decides the plan. Keep the area protected and dry in the truck on the way in instead of thawing it at the pad.

Trench foot first aid

Trench foot surprises people because it doesn't need freezing weather. OSHA says it can happen at 60°F if feet stay wet, because wet feet lose heat 25 times faster than dry feet. Think of a day spent in a flooded cellar, on a wash-out or standing in water during a spill job. First aid is simple: get medical help, take off the wet boots and socks, dry the feet, keep them raised and stay off them, since walking can cause more tissue damage (OSHA Cold Stress).

Why wind chill matters on an open pad

West Texas has very little to block a north wind, and that wind drives how fast exposed skin cools. The National Weather Service figures wind chill for air temperatures at or below 50°F with wind over 3 mph. On its chart, 0°F air with a 15 mph wind feels like -19°F, and exposed skin can freeze in about 30 minutes (National Weather Service). Wind chill isn't only a deep-winter number, either. OSHA's example is 40°F air with a 35 mph wind, which works out to a wind chill of 28°F (OSHA Cold Stress). Check the forecast wind, not just the temperature, when you plan a cold-day job.

Controls that prevent cold stress

OSHA has no specific standard for working in the cold. Employers still have a duty under the General Duty Clause to protect workers from recognized hazards, including cold stress. OSHA's recommended controls are practical for field crews (OSHA Cold Stress):

• Schedule frequent short breaks in warm, dry areas, and do the worst work in the warmest part of the day.
• Use the buddy system so someone is watching for shivering, confusion and white patches on skin.
• Provide warm, sweet drinks and high-carbohydrate snacks. Skip alcohol.
• Avoid touching cold metal or wet surfaces with bare skin.
• Use radiant heaters where the job allows it.
• Keep an eye on new workers and anyone coming back after time off, since they may not be used to the cold.

OSHA also lists the risk factors to watch: wet or damp clothing, dressing wrong for the weather, exhaustion, poor physical condition, and health problems such as hypertension, hypothyroidism and diabetes (OSHA Cold Stress). A crew that sweats through its layers rigging up in the morning is set up for hypothermia when the wind picks up in the afternoon. Bring dry spares.

What cold stress training should cover

OSHA says workers should be trained on how to recognize the environmental and workplace conditions that cause cold stress, the symptoms, how to prevent it and what to do if someone is affected (OSHA Cold Stress). That fits into a first aid class alongside heat illness. For the summer side of the same problem, see our heat stroke vs. heat exhaustion guide, and for kit and responder rules on remote leases, see OSHA first aid requirements for remote sites.