The acid mantle is a very thin, delicate, slightly acidic film covering the entire surface of human skin, serving as a protective barrier against pathogens and reduces body odor.
[3][2] While the viable epidermis below the stratum corneum has a neutral pH of around 7.0, the surface pH of the skin's acid mantle typically ranges between 4.5 and 6.5,[4][5] with an average assumption of 5.0 to 6.0.
[3] Recent research has challenged these proposed ranges, finding that healthy human skin naturally tends to return to acidity levels below 5.0 when left untouched by skincare products or water for extended periods.
An ideal pH value of 4.7 has been identified, with some individuals showing levels as low as 4.3.
[6] The acidic surface pH is crucial for the growth conditions of resident skin microbiota, which play a vital role in maintaining skin health.