The thermal protection offered by lightweight survival systems.

The thermal protection offered by lightweight survival systems was evaluated in a mountain environment. When subjects were exposed for 3 h in bags manufactured from polythene, in metallised plastic sheeting, and in a casualty bag incorporating MPS, no significant differences in thermal benefit were found. The protection offered by each system was comparable and the practical experience gained in the field would suggest that the simple polythene bag was superior to the MPS bag when one considers strength, durability, multiplicity of roles, and cheapness. Addition of a fibre pile liner equivalent to 1.5 clo units during exposure in the MPS-lined casualty bag effectively eliminated cold stress and metabolic compensation. Without this liner, the thermal performance of the casualty bag was very similar to the other two lightweight systems.