In mammals, perspiration is a physiological response that aids in thermoregulation. Sweat glands typically excrete perspiration as a fluid mixture of various chemical components. For example, human perspiration is a fluid mixture consisting primarily of water, urea, 2-methyphenol (o-cresol), 4-methylphenol (p-cresol), and various dissolved chlorides.
Human perspiration rates vary widely depending on numerous factors including outdoor temperature and/or climate, amount of physical activity, physical activity intensity, gender, the presence or absence of various congenital or acquired medical conditions (e.g., hyperhidrosis, focal hyperhidrosis, etc.), emotional stress including anxiety, etc. For example, under certain environmental and working conditions (e.g., outdoor, manual labor during summer in a temperate climate), studies have shown that humans can perspire up to 12 liters per day. Even under climate controlled conditions (e.g., indoors at temperatures between 72 to 76° F.), the average sedentary human body has been shown to perspire between 400 mL and 4 liters. In addition, human studies have shown that men typically begin perspiring much more quickly than women, and in certain instances, perspire more than twice as much as women while being subjected to similar conditions.
Although many people believe that human perspiration leads to body odor, this belief is ill founded. While human perspiration includes dissolved solutes, human perspiration is typically odorless and/or virtually undetectable by human olfaction. However, certain odor causing bacterial flora such as S. epidermidis and members of the Corynebacterium genus reside on the human body. These odor causing bacterial flora often feed on human perspiration and create odorant substances when metabolizing human perspiration. Thus, a person with a high odor causing bacterial flora or a person who excessively perspires while having an average amount of odor causing bacterial flora can potentially be more prone to body odor and/or to producing body odor causing substances either while or after perspiring.
In certain occupational and social settings, negative social stigmas and connotations can arise from perspiration and/or body odor indirectly caused from perspiration. For example, certain individuals may find the slightest amount of perspiration that “bleeds through” the outer surface of a fabric, such as the outer surface of a shirt, both undesirable and/or unprofessional.