The "Antifog" property refers to a surface treatment that actively prevents fogging of glasses, visors or other transparent materials. Fogging occurs when warm, moist air, for example from human breath or sweat, meets a cooler surface. Water vapour precipitates on this surface in the form of microscopic droplets that scatter light and form an opaque coating. Antifog-treated material has a special hydrophilic layer applied to it that attracts water. Rather than condensing moisture into thousands of tiny droplets, this layer spreads it into a continuous, very thin and transparent water film. It is possible to see through this film without distortion, maintaining good visibility even during physical activity or transition between different temperatures.