For a dry person, where should the vapor barrier be placed when applying a hypothermia wrap?

• A. Outside insulation wrap
• B. Inside insulation wrap
• C. Not used
• D. Between clothing layers

Answer: (A)

The main idea is that a vapor barrier reduces heat loss by stopping water vapor from moving from the inside toward the outside. For a dry person, you want to minimize evaporative cooling and keep warmth trapped inside. Placing the vapor barrier on the outside of the insulation wrap puts that barrier at the outer edge, preventing warm, moist air from escaping to the environment while allowing the insulation to do its job. If the barrier were inside the insulation, moisture could be trapped against the skin and the insulation could lose its effectiveness, and not using a barrier or placing it between layers would let more heat escape. So the vapor barrier should be outside the insulation wrap.