正文
Human skin is densely covered with sweat glands. For instance, our palms and soles contain 250 to 550 sweat glands per square centimeter, which is roughly the size of an adult's fingernail.
While sweating due to exercise, overheating or stress is obvious, the body continuously releases moisture through a process called insensible perspiration, sweating that is too subtle to feel.
图源：视觉中国
汗水含有很多的微量成分，比如钠离子、氯离子、钾、维生素和矿物质以及其他的一些代谢产物等。
尤其在腋窝、私密处等部位，还会有特殊的汗腺，我们叫做大汗腺。
它产生的汗水黏稠、油分重，还有蛋白质、糖和氨，再加上细菌的“催化”，更容易产生汗臭味。
如果这种汗臭味更严重一些，就是我们说的狐臭、腋臭了。
Areas with apocrine glands, such as armpits, produce thicker, oilier sweat that is rich in proteins, sugars and ammonia. When broken down by bacteria, this mixture can lead to body odor or conditions like bromhidrosis, or excessive body odor, and axillary osmidrosis, or severe underarm odor.
我们拿数据说话，以正常成年男性为例，体表面积大概是1.75 平方米，研究发现，在环境温度分别为22℃、27℃和30℃的时候，休息状态下，每天不显性出汗的总量分别是381毫升、526毫升和695毫升。
也就是说，
人啥都没做，每天皮肤都会悄悄地排掉差不多一瓶饮料的汗水。
