Military Operational Protective Posture (MOPP). In a CRBN (Chemical Radiological Biological Nuclear) environment, soldiers are given charcoal infused suits that protect from those effects. MOPP-1 is just the suit. MOPP-2 is the suit and boots, etc, etc. While in MOPP-4, you are covered from head to toe in a thick suit, rubber boots on top of your real boots, rubber gloves on top of your real gloves that you only have to wear because the rubber ones are so uncomfortable, and a gas mask with a hood. Air cannot escape. Heat cannot escape. I imagine walking around in hell would be the equivalent.