Climate Changes In The Skin

Climate Changes In The Skin

While the skin can be extremely resilient, the skin barrier itself is sensitive to several factors like humidity, temperature, and pH, and requires the right conditions to function optimally.1,2

Effect of dryness on the skin

You might have noticed that your skin seems to be more prone to dryness when there is a change in climate. While this may be partly explained by factors like low humidity and fluctuating temperatures,3 there are also physical changes happening in the skin. Key skin lipids, including ceramides, which are crucial to the skin’s normal barrier function, appear to be reduced during low temperature.4 Ceramide levels may be reduced by as much as 40%, resulting in a weaker skin barrier that loses water more quickly.5

That’s why it is especially important to moisturise your skin frequently during the low temperature.

Effect of humidity on the skin

While some people may think that heat and humidity are one and the same, there are key differences. Heat refers to the air temperature, whereas humidity is the amount of moisture held in the air. How they interact can have a huge impact on how you (and your skin) feel: hot, dry heat can be unpleasant, but the low humidity means that sweat can evaporate and produce a cooling effect on your skin. Conversely, a humid heat can be almost unbearable as sweat drops from the skin rather than evaporating from it, and the moisture held in the air actually makes it feel hotter than it is. 

While most studies confirm that low humidity leads to dry skin, others have found that the skin’s barrier function can also be impacted by higher humidity.6 High humidity can decrease skin elasticity, increase sebum production and lower skin pH.7 What’s more, sudden, dramatic changes in humidity—such as moving from a very humid outdoor environment to a temperature-controlled building—may cause the skin to lose more moisture than normal.3

Even in humid climates, skin can lack hydration. When the skin is not properly hydrated, the outermost skin cells become shrivelled, leading to dry, flaky skin and a weakened skin barrier. A disrupted skin barrier is also more susceptible to irritants.8

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References:

1. Engebretsen KA, Johansen JD, Kezic S, Linneberg A, Thyssen JP. The effect of environmental humidity and temperature on skin barrier function and dermatitis. J Eur Acad Dermatol Venereol 2016;30(2):223–49.
2. Lambers H, Piessens S, Bloem A, Pronk H, Finkel P. Natural skin surface pH is on average below 5, which is beneficial for its resident flora. Int J Cosmet Sci 2006;28(5):359–70.
3. Sato J, Denda M, Chang S, Elias PM, Feingold KR. Abrupt Decreases in Environmental Humidity Induce Abnormalities in Permeability Barrier Homeostasis. J Invest Dermatol 2002;119(4):900–4.
4. Rogers J, Harding C, Mayo A, Banks J, Rawlings A. Stratum corneum lipids: the effect of ageing and the seasons. Arch Dermatol Res 1996;288(12):765–70.
5. Muizzuddin N, Ingrassia Mi, Marenus KD, Maes DH, Mammone T. Effect of seasonal and geographical differences on skin and effect of treatment with an osmoprotectant: Sorbito. J Cosmet Sci 2013;64(3):165–74.
6. Denda M, Sato J, Masuda Y, Tsuchiya T, Koyama J, Kuramoto M et al. Exposure to a dry environment enhances epidermal permeability barrier function. J Invest Dermatol 1998;111(5):858–63.
7. Lee M, Jung Y, Kim E, Lee HK. Comparison of skin properties in individuals living in cities at two different altitudes: an investigation of the environmental effect on skin. J Cosmet Dermatol 2017;16(1):26–34.
8. Baumann L. Dry skin. In: Cosmetic dermatology - principles & practice. Hong Kong: The McGraw-Hill Companies; 2002. page 29–32.