A breathable material allows moisture vapour from within the garment to escape to the outside edge of the fabric, where it evaporates.

The correct term for breathability is: Moisture Vapour Transmission (M.V.T.)

Therefore a breathable garment will:

• Repel water (rain, sleet and snow).
• Repel Wind
• Allow M.V.T. to take place

Condensation (moisture) forms on the inside edge of the layer.  This is a direct result of warm body vapours (perspiration) meeting the cooler temperatures on the outside edge of the fabric.

A Breathable Fabric Reduces Condensation Build Up

If condensation is allowed to build up a “chilling effect” can occur.  The more vigorous the exercise, the greater the amount of perspiration produced.  The surface of the skin will then become damp and cooling of the body will take place.

Chilling is potentially very dangerous.  Fatigue and rapid tiring will follow if the condensation has no means of escape (M.V.T).