Transepidermal water loss

Passage of water through the outermost layer of an animal or plant to the atmosphere

Transepidermal water loss is the loss of water that passes from inside a body through the epidermis to the surrounding atmosphere via diffusion and evaporation processes. TEWL in mammals is also known as insensible water loss (IWL), as it is a process over which organisms have little physiologic control and of which they are usually mostly unaware. Insensible loss of body water can threaten fluid balance; in humans, substantial dehydration sometimes occurs before a person realizes what is happening.

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