OBJECTIVES: Skin characteristics change depending on the external environment such as UV, temperature and humidity. But the research how to affect the regional climate, age and seasonal variation on the skin conditions was not well studied. Therefore, we investigated the seasonal variation in the skin by comparing Beijing women and Guangzhou women by age groups. METHODS: 440 healthy Chinese women participated in this study. The skin hydration, sebum secretion, TEWL and skin pH were measured on the cheek front. All the parameters were analyzed in terms of the age, season and region. RESULTS: The skin hydration in Beijing was lower than that in Guangzhou and significantly decreased during winter than summer. The sebum secretion in their 20s and 30s was significantly high in summer in both regions, and this phenomenon was more remarkable in Guangzhou ( p < 0.05). The skin pH increased with age during winter, but it decreased in the old age groups in Beijing during summer. TEWL increased during winter, and differences in TEWL between summer and winter were greater in the old age groups. CONCLUSIONS: Skin hydration and barrier function decreased more during a cold, dry winter than summer. The barrier dysfunctions such as an increase in TEWL and pH occurred more commonly in old age groups. The greater the differences between summer and winter climates, the greater damage to skin barrier and skin hydration. The sebum secretion was more affected by hot, humid summers. Further, the aged skin was influenced by seasonal variation except for sebum secretion.
As an organ on the outermost layer of the human body, the skin plays various roles such as protecting the internal tissue from external factors, regulating body temperature, excreting waste from the body, and responding to external stimuli [
We hypothesized that the varying effect of summer and winter climates on skin may differ in two regions with completely different climates as age increases. Therefore, we compared and assessed the skin characteristics of women living in Guangzhou and Beijing in China during the seasonal change of winter and summer.
440 healthy Chinese women (Beijing 224, Guangzhou 216) aged between 20 and 65 years participated in this study from 2011 to 2012 (
All physical assessments were performed on the subject’s cheek front. The test
Beijing | Guangzhou | |||
---|---|---|---|---|
Age group | Mean ± SD | n | Mean ± SD | n |
20s | 24.79 ± 2.29 | 90 | 26.14 ± 2.00 | 74 |
30s | 35.52 ± 2.72 | 27 | 35.06 ± 3.16 | 49 |
40s | 44.13 ± 3.09 | 62 | 44.45 ± 2.97 | 56 |
50s | 55.20 ± 3.63 | 45 | 54.59 ± 4.01 | 37 |
Beijing | Guangzhou | |||
---|---|---|---|---|
Temp. (˚C) | RH (%) | Temp. (˚C) | RH (%) | |
Winter | −1.60 ± 1.21 | 42.58 ± 4.17 | 14.82 ± 1.60 | 68.38 ± 5.81 |
Summer | 26.31 ± 0.39 | 64.92 ± 2.60 | 28.73 ± 0.47 | 76.75 ± 3.23 |
sites were acclimated to the environment (22˚C ± 2˚C, 40% ± 10% RH) for 20 minutes, after they were washed with soap before the assessment was performed.
The skin surface pH and skin hydration were measured with a pH meter PH905 and Corneometerâ CM825 in MPA 580 (Courage + Khazaka Electronic GmbH Cologne, Germany). The Sebumeterâ SM815 in MPA 580 (Courage + Khazaka Electronic GmbHCologne, Germany) was used to quantify the amount (µg/cm2) of sebum on the test sites. We measured the TEWL of the stratum corneum with a Vapometer (Delfin Technologies, Ltd. Kuopio, Finland), which had a closed chamber system.
SPSSâ version 22.0 (SPSS Inc. Chicago, USA)) was used to perform the statistical analysis. Normally distributed data were analyzed using the Kolmogorov-Smir- nov test. Differences among the physical parameters of the skin in the two regions were analyzed by age groups with the analysis of variance test. P-values less than 0.05 were considered statistically significant.
The skin hydration of women in Beijing and Guangzhou did not correlate with age. Although the skin hydration of Beijing women significantly increased in all age groups during summer compared to winter, only the skin hydration of Guangzhou women in their 50s was significantly low during the winter (
Skin hydration in winter was significantly lower in Beijing women than in Guangzhou women, except for women in their 50s. Although the skin hydration
of women in their 20s during summer was significantly higher in Beijing women than in Guangzhou women, there was no significant difference among the other age groups.
Among Beijing and Guangzhou women, those in their 20s and 30s had a significant difference in the amount of sebum secretion during summer and winter (
The skin pH during summer and winter had completely different patterns in Beijing and Guangzhou women (
In Guangzhou women, the skin pH increased in proportion to age during summer and winter. Only women in their 20s had a significantly lower skin pH during the winter than in summer. The skin pH was not different between summer and winter in the other age groups. The skin pH during the winter was
significantly higher in Beijing women than in Guangzhou women. During summer, the skin pH of women in their 20s and 30s was significantly higher in Beijing women than in Guangzhou women, whereas the skin pH of women in their 40s and 50s was significantly higher in Guangzhou women than in Beijing women.
TEWL increased more significantly in Beijing and Guangzhou women during winter than during summer, except for Beijing women in their 20s (
Women in their 40s and 50s had a greater difference in the TEWL between summer and winter than women in their 20s and 30s. The TEWL of women in their 20s during winter was significantly higher in Beijing women than in Guangzhou women. The TEWL of women in their 20s and 30s during summer was significantly higher in Beijing women than in Guangzhou women. There was no significant difference in the TEWL between Beijing and Guangzhou women in the other age groups.
Beijing is very cold and dry with an average temperature of −1.60˚C ± 1.21˚C and humidity of 42.58% ± 4.17% during winter. In summer, it has a hot, humid climate with an average temperature of 26.31˚C ± 0.39˚C and humidity of 64.92% ± 2.60%. Thus, there is a greater difference in the temperature and humidity between winter and summer. Guangzhou is located on the southern coast in China, and even in winter, the climate is mild, not dry, with an average temperature of 14.82˚C ± 1.60˚C and humidity of 68.38% ± 5.81%. In summer, it has a hot, humid climate with an average temperature of 28.73˚C ± 0.47˚C and humidity of 76.75% ± 3.23%. Thus, there are significant climatic differences in winter and summer between these two regions. Because of these climatic differences, the skin of women in Beijing and Guangzhou was very different in terms of the skin hydration, skin pH, sebum secretion, and TEWL.
Although the skin hydration did not correlate with an increasing age [
As the skin physiological parameters are greatly affected by seasonal variation, sebum is secreted more in a hot climate during summer, thereby causing very oily skin [
The skin pH is the main factor that affects skin barrier functions, skin integrity, and skin microbial ecology. The stratum corneum forms the acid mantle by exogenous and endogenous mechanisms such as the Na+/H+ antiporter, secretory phospholipase, sebum, and sweat [
As the skin ages, the skin pH increases [
The TEWL generally tends to increase during the cold, dry season [
In conclusion, in Beijing where the winter is cold and dry, and the climatic difference between summer and winter is greater, Chinese women experienced decreased skin hydration and increased skin pH and TEWL in winter than in summer. In particular, barrier dysfunction such as an increased TEWL and pH occurred more significantly in the old age groups. In Guangzhou where the climatic difference between summer and winter is minimal since the winter is warm and very humid, the amount of sebum secretion of young women in their 20s to 30s decreased sharply in winter, but there was no significant difference in the other skin characteristics. Thus, the damage to skin barrier function caused by the climatic difference between summer and winter increases as the climatic variation and age increase.
The authors state no conflict of interest.
Kim, E., Han, J., Park, H., Kim, M., Kim, B., Yeon, J., Wei, L., Wei, L. and Lee, H. (2017) The Effects of Regional Climate and Aging on Seasonal Variations in Chinese Women’s Skin Characteristics. Journal of Cosmetics, Dermatological Sciences and Applications, 7, 164-172. https://doi.org/10.4236/jcdsa.2017.72014