ABSTRACT
The skin, being the largest organ, covers the entire exterior of the body and thus forms a protective barrier between the human body and its environment. It has a complex and dynamic microbial ecosystem; some areas are moist like a rainforest, and others are dry like a desert. The tough and dry exterior signies the physical character of the skin covering most parts of the body. The uppermost layer of the skin is a multilayered structure called the stratum corneum (SC). The top three to ve layers of SC undergo progressive desquamation. The morphology and thickness of SC is different at various body sites [1-3]. The skin maintains characteristic physicochemical features such as structure, hydration, temperature, pH, oxygen, carbon dioxide gradients, and so forth. Changes in any of these features impact the overall physiology of the skin. The acidic nature of the skin was discovered in 1892 by Heuss [4] and was later validated in 1928 by Schade and Marchionini [5], who underlined acidity as its protective feature and called it the “acid mantle.” Current literature indicates that the skin surface pH ranges from 4.0 to 7.0, but it is mostly acidic, between 5.4 and 5.9 [6].
