Skin Research and Technology 2014; 0: 1–8 Printed in Singapore All rights reserved doi: 10.1111/srt.12145
© 2014 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd Skin Research and Technology
The seasonal variation in skin hydration, sebum, scaliness, brightness and elasticity in Korean females G. W. Nam1, J. H. Baek2, J. S. Koh2 and J.-K. Hwang3 1
2
Skin Research Institute, Amorepacific R&D Center, Seoul, Korea, Dermapro Skin Research Center, DERMAPRO LTD., Seoul, Korea and 3Department of Biomaterials Science and Engineering, Yonsei University, Seoul, Korea
Background/purpose: Age, gender, regional, and ethnic differences influence skin conditions. The purpose of this study was to observe the effects of environments, especially the air temperature, relative humidity, air pressure, duration of sunshine, and precipitation on skin, and the seasonal variation in skin hydration, sebum, scales, brightness, and elasticity in Korean females. Methods: The study included 89 Korean subjects, aged 29.7 6.2 years. The five skin biophysical parameters (skin hydration, sebum, scales, brightness, and elasticity) were measured at six sites: forehead, under the eye, frontal cheek, crow’s foot, lateral cheek, and inner forearm. Skin hydration was measured using the Corneometerâ CM 825. Skin sebum was measured with Sebumeterâ SM 815. Skin scaliness was measured with Visioscanâ VC 98. Skin brightness (L* value) was measured by using Spectrophotometer. A suction chamber device, Cutometerâ MPA 580, was used to measure the skin elasticity. The measurements were performed every month for 13 months, from April 2007 to April 2008. Results: There were significantly seasonal variations in environmental factors. The air temperature was the lowest in
January ( 1.7°C), and the highest in August (26.5°C). The relative humidity was the lowest in February (46%), and the highest in July and August (75%). There was a negative correlation between skin scaliness and three environmental factors such as air temperature, relative humidity, and highest precipitation. There was a positive correlation between skin scaliness and two environmental factors such as air pressure and duration of sunshine. Elasticity was correlated with air temperature positively and with air pressure negatively. Conclusion: The correlations shown between the skin biophysical parameters and environmental factors demonstrate that the skin biophysical parameters are affected by environmental factors.
and extrinsic factors, such as age, gender, and regional and ethnic difference affect the skin’s physiological and biophysical parameters. Previously, age-dependent decreases of transepidermal water loss, stratum corneum (SC) hydration on the forehead, dermal elasticity of the facial skin, and sebum content of nasolabial area have been reported (1–4). Skin surface pH on the forehead of old people is higher than that in young people (2). In the reports concerning gender differences related with the skin, the melanin and erythema indexes are higher and sagging at the lower eyelid is more severe in men than in women
(3, 5, 6). Many reports on ethnic and regional differences in skin properties have also been published (7–10). However, atmospheric condition and climate is an important factor influencing the skin physiology. Qiu et al. reported that skin hydration and density for hyper-pigmented spots increased in summer as compared with winter season (11). Roh et al. also showed that several regions (V-neck and dorsal forearm) of the body have increased pigmentation in summer (12). Abe et al. studied the seasonal variation (four different seasons) of skin temperature, skin pH, evaporative water loss (EWL), and skin surface lipid of the forearm in a Japanese population. They found that TEWL and lipid values in July (summer) were approximately two to three times those in January
V
ARIOUS INTRINSIC
First two authors contributed equally to this work.
Key words: skin – seasonal variations – Korean female – non-invasive
Ó 2014 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd Accepted for publication 5 January 2014
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Nam et al.
(winter), April (spring), or October (fall), and that skin pH in July (summer) was significantly lower than January (winter) (13). Youn et al. reported definitive regional and seasonal variations in sebum secretion (14). Tsukahara et al. also showed seasonal environmental changes affected eye wrinkle depth (15). The aim of this study was to observe the annual variations of sebum, hydration, scale, skin color, and elasticity in Korean females and the correlation between annual variations of them and environment changes of air temperature, relative humidity, air pressure, duration of sunshine, and precipitation.
Material and Methods Acquisition of climate information Climate data were collected from ‘Annual climatological report’ published by Korea meteorological administration. Daily mean values of air temperature were computed from the 3-hourly observations measured at 03, 06, 09, 12, 15, 18, 21, and 24 h. One-day greatest value is the largest amounts of precipitation measured in a day. Evaporation is measured from 09 h to 09 h of the following day. The duration of sunshine is measured by a rotating-type sunshine recorder.
Subjects and study design The study was conducted according to the principles of the Declaration of Helsinki. Volunteers gave written informed consent to participate in the study. In total, one hundred and fifty-one healthy female volunteers (aged 20–39 years) were enrolled for this study in the beginning. Following were exclusion criteria, (i) pregnant woman and women scheduled to be pregnant (ii) infectious skin disease patients (iii) received anti-immunologic therapy within 3 month. (iv) used steroid drugs within 1 month (v) serious kidney or liver disease patients (vi) diabetes, hypertension, or asthma patients (vii) atopic patients (viii) have severe allergy to cosmetics or drugs (ix) have lesions on measurement site (x) is incapable of giving informed consent. Thirteen months later, eighty-nine healthy female volunteers, aged 29.7 6.2 years (20–38 years) remained. The female volunteers were consisted of thirty-nine females of 20s (aged 23.4 2.8 years) and fifty females of 30s (aged 34.7 2.2 years).
2
All volunteers lived in Seoul (north latitude 37.34, east longitude 126.57). The measurements were performed every month for 13 months, from April 2007 to April 2008. Volunteers were allowed to relax in the room maintained at a temperature of 22 2°C and a relative humidity of 50 5% for 20 min, after washing their face and arms with cleanser. The five skin biophysical parameters (skin hydration, skin sebum, skin scaliness, skin color, and skin elasticity) were measured at six sites: forehead, under the eye, frontal cheek, crow’s foot, lateral cheek, and inner forearm. All measurements, except for skin elasticity, sebum, and skin scaling, were measured 3 times. In addition, the average data were used for the data analysis.
Measurement of skin hydration The skin hydration in the stratum corneum was measured with a Corneometer CM825 (Courage1Khazaka Electronic GmbH, Cologne, Germany) based on a capacitance measurement. We measured the capacitance value three times, and the averages of the values were water contents.
Measurement of sebum secretion Measurements of sebum were performed with the Sebumeterâ SM 815 (Courage & Khazaka Electronic GmbH, Cologne, Germany). It is a direct measurement of the sebum secretion on skin. The measurement principle is the photometric method, the grease spot photometer. A microprocessor calculates the result, which is shown on the display in lg sebum/cm2 of the skin. Each value was the average of three measurements. Measurement of skin scaliness Skin scaliness was measured Visioscanâ VC 98 (Courage & Khazaka, Cologne, Germany). It is a special UVA-light video camera with high resolution. The scaliness parameter was analyzed with the software.
Measurement of skin brightness Skin brightness was measured using a spectrophotometer CM-2500D (Konica Minolta, Inc., Tokyo, Japan). The melanin and erythema
Seasonal variation in skin biophysical parameters
indexes, CIE L*a*b* color coordinates, and the Munsell value (hue, value, and chroma) could be shown almost at the same time as the measurement, and the results were presented with graphs on the screen. We measured L* value for skin brightness three times, and calculated the averages of the triplicates.
Measurement of skin elasticity Skin elasticity was measured by Cutometer MPA 580â (Courage & Khazaka, Cologne, Germany). Subjects lay on a bed and inclined their face at an angle of 45° to reduce the effect of gravity on the measured values of dermal elasticity and subcutaneous adipose mass. Using a 2-mm probe, a negative pressure of 450 mbar was applied to the skin for a period of 2 s, followed by a 2 s relaxation time. The skin elasticity was analyzed R2 {Ua/Uf: gloss elasticity, Portion between the max. amplitude and the ability of re-deformation of the skin (gross elasticity), the closer the value is to 1 (100%), the more elastic the curve}.
Statistics The collected data were analyzed using SPSS (version 19.0; SPSS Inc., Chicago, IL, USA). To compare the measurement time points, RM-ANOVA tests were used. In addition, correlations between climate conditions and physiology parameters of facial skin were calculated using Pearson’s correlation coefficient.
Results Climate variations Table 1 shows the data for air temperature, relative humidity, air pressure, duration of sunshine, and highest precipitation. The air temperature was the lowest in January ( 1.7°C), and the highest in August (26.5°C). The relative humidity was the lowest in February (46%), and the highest in July and August (75%). The air pressure was the lowest in July (994.7 hPa), and the highest in January (1,015.5 hPa). The duration of sunshine was the lowest in September (85.1 h), and the highest in April 2008 (208.1 h). The highest precipitation was the lowest in December (2.5 mm), and the highest in July (76.0 mm).
Seasonal variation in skin hydration The crow’s foot showed the highest value in 6 test sites (Table 2). Skin hydration in the crow’s foot was significantly higher when compared with the inner forearm and lateral cheek (P < 0.05). There was a clear seasonal variation in skin hydration, the skin hydration level of face from April 2007 to 2008 ranged from 49.48 12.23 to 57.18 11.38 (Table 2 and Fig. 1a). The mean value (arbitrary unit) of skin hydration for thirteen months were; April (2007) 49.48 12.23, May 52.19 11.96, June 54.61 11.76, July 56.00 11.67, August 57.18 11.38, September 55.44 10.85, October 55.39 10.84, November 52.59 10.32, December 52.22
TABLE 1. Climate information of study region (Seoul, South Korea) for 13 months 2007 Year Month
4
2008 5
Air temperature(°C) Mean 11.4 18.1 Maximum 22.6 30.1 Minimum 1.6 9.0 Relative humidity (%) Mean 53 62 Lowest 14 17 Air pressure (0.1 hPa) Mean 10,056 9,978 Highest 10,281 10,188 Lowest 10,059 9,898 Duration of sunshine (0.1 hr) Total 1,918 1,973 Highest precipitation (0.1 mm/day) Mean 260 490
6
7
8
9
10
11
12
1
2
3
4
23.2 33.2 14.1
24.2 31.2 17.7
26.5 33.2 19.8
21.5 31.1 14.1
15.1 26.2 3.2
6.7 19.3 5.5
1.8 13.8 7.4
7.3 19.8 1.7
14.1 28 3.8
61 13
75 35
75 23
74 36
63 13
55 16
60 24
50 13
46 12
56 10
50 11
9,985 10,139 9,986
9,947 10,121 9,957
9,987 10,169 9,969
10,025 10,229 10,037
10,094 10,273 10,102
10,132 10,343 10,146
10,118 10,347 10,111
10,155 10,389 10,151
10,142 10,381 10,043
10,079 10,292 10,053
10,050 10,224 10,041
1,752
915
1,057
851
1,709
1,885
1,408
1,665
2,242
1,873
2,081
220
760
420
485
220
150
25
67
74
275
115
1.7 7.3 11.1
1.2 10.5 10.1
3
Nam et al. TABLE 2. Monthly variations of hydration, sebum, scaliness, brightness, and elasticity in Korean females (N = 89) Time 2007 Parameter
Test site
April
Hydration
Forehead Under the eye Frontal cheek Crow’s foot Lateral cheek Face Inner forearm Forehead Under the eye Frontal cheek Crow’s foot Lateral cheek Face Inner forearm Forehead Under the eye Frontal cheek Crow’s foot Lateral cheek Face Inner forearm Forehead Under the eye Frontal cheek Crow’s foot Lateral cheek Face Inner forearm Forehead Under the eye Frontal cheek Crow’s foot Lateral cheek Face Inner forearm
49.35 55.69 45.23 62.89 34.24 49.48 31.00 38.40 8.35 21.3 9.67 5.52 16.66 0.93 0.16 0.09 0.29 0.09 0.36 0.20 0.58 61.82 62.53 63.55 63.53 66.29 63.54 67.32 0.79 0.79 0.77 0.84 0.89 0.82 0.92
Sebum
Scaliness
Brightness
Elasticity
May
9.96 13.80 13.38 11.68 12.34 12.23 7.87 22.73 8.85 15.08 11.07 6.79 12.90 2.09 0.33 0.17 1.13 0.22 1.50 0.67 1.20 2.66 2.49 2.69 2.53 2.84 2.64 2.25 0.08 0.07 0.08 0.09 0.05 0.07 0.03
50.66 59.34 48.05 64.27 38.65 52.19 32.20 29.82 7.92 15.98 7.33 4.21 13.05 0.36 0.26 0.14 0.12 0.14 0.07 0.14 0.45 62.43 62.40 64.90 64.46 66.54 64.14 68.04 0.78 0.80 0.79 0.85 0.90 0.82 0.93
June
11.80 12.75 12.71 12.00 10.54 11.96 7.18 23.92 8.99 13.38 7.32 6.38 12.00 0.73 0.75 0.39 0.32 0.64 0.11 0.44 1.23 3.22 3.35 3.60 2.98 3.31 3.29 2.79 0.09 0.07 0.08 0.07 0.04 0.07 0.02
10.16, January (2008) 55.45 10.98, February 54.95 11.71, March 55.08 13.92, April 55.27 12.44. Seasonal variation in sebum secretion The forehead showed the highest value in 6 test sites (Table 2). Sebum secretion in the forehead was significantly higher when compared with the inner forearm, under the eye and crow’s foot (P < 0.05). There was a clear monthly variation in sebum secretion for forehead and frontal cheek, the sebum secretion of face from April 2007 to 2008 ranged from 9.27 8.33 to 16.66 12.90 (Table 2 and Fig. 1). The mean value (lg/cm2) of sebum secretion for thirteen months were; April (2007) 16.66 12.90, May 13.05 12.00, June 9.85 10.21, July 11.88 11.51, August 8.10 8.18, September
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July
54.16 60.68 51.49 68.22 38.48 54.61 32.80 23.02 5.19 11.43 6.34 3.28 9.85 0.27 0.15 0.08 0.12 0.04 0.08 0.10 0.17 61.79 62.27 63.86 63.85 65.93 63.54 67.05 0.79 0.80 0.80 0.85 0.90 0.83 0.92
11.06 12.06 13.05 10.30 12.30 11.76 6.42 18.30 6.93 9.98 11.37 4.44 10.21 0.78 0.45 0.25 0.36 0.07 0.24 0.27 0.35 2.79 2.34 2.94 2.22 2.55 2.55 2.33 0.08 0.07 0.07 0.07 0.05 0.07 0.03
55.31 65.48 51.91 69.32 37.96 56.00 34.57 25.03 8.09 13.96 8.33 4.01 11.88 0.56 0.08 0.08 0.11 0.05 0.06 0.08 0.09 61.39 61.81 63.98 63.66 65.70 63.31 66.37 0.79 0.77 0.79 0.83 0.88 0.81 0.91
August
11.25 13.06 12.47 10.52 11.03 11.67 6.08 19.08 10.14 15.26 7.82 5.24 11.51 1.04 0.16 0.18 0.30 0.11 0.11 0.17 0.25 2.86 2.35 2.73 2.44 2.79 2.63 2.37 0.07 0.07 0.06 0.07 0.05 0.06 0.02
56.42 65.48 54.95 68.65 40.40 57.18 34.80 23.47 6.64 14.37 6.96 4.43 8.10 0.39 0.06 0.12 0.08 0.05 0.08 0.08 0.17 61.22 61.60 63.62 62.88 65.15 62.90 65.80 0.77 0.77 0.78 0.83 0.87 0.80 0.91
September 10.51 11.85 13.31 10.01 11.21 11.38 5.53 17.89 6.94 11.41 7.82 6.56 8.18 0.78 0.15 0.29 0.17 0.07 0.13 0.16 0.54 2.73 2.38 2.78 2.41 2.55 2.57 2.50 0.08 0.07 0.08 0.08 0.04 0.07 0.03
53.87 63.91 52.15 67.97 39.31 55.44 32.52 30.16 7.51 15.83 8.08 5.19 13.35 0.34 0.25 0.09 0.15 0.09 0.09 0.13 0.27 61.32 61.70 63.47 62.87 65.16 63.30 65.54 0.79 0.78 0.78 0.83 0.88 0.83 0.91
12.11 11.27 10.74 9.67 10.43 10.85 5.19 26.87 11.06 14.67 12.12 7.92 14.53 0.74 1.15 0.20 0.49 0.14 0.23 0.44 0.67 2.68 2.68 2.60 2.50 3.01 2.70 2.39 0.07 0.06 0.06 0.07 0.04 0.06 0.02
13.35 14.53, October 12.46 11.44, November 9.78 10.71, December 10.01 9.59, January (2008) 9.54 8.14, February 9.27 8.33, March 11.71 10.91, April 13.06 13.53. Seasonal variation in skin scaliness The forehead showed the highest value in 6 test sites (Table 2). Skin scaliness in the forehead was significantly higher when compared with other test sites (P < 0.05). There was a clear monthly variation in sebum scaliness for forehead, the skin scaliness of face from April 2007 to 2008 ranged from 0.08 0.17 to 0.22 0.56 (Table 2 and Fig. 1). The mean value (%) of skin scaliness for thirteen months were; April (2007) 0.20 0.67, May 0.14 0.44, June 0.10 0.27, July 0.08 0.17, August 0.08 0.16, September 0.13 0.44, October 0.12 0.37, November
Seasonal variation in skin biophysical parameters
2008 October 52.45 62.68 50.43 69.16 42.24 55.39 33.51 27.22 7.66 13.78 8.852 4.80 12.46 0.53 0.25 0.13 0.16 0.10 0.14 0.12 0.49 61.25 60.92 63.07 63.08 64.56 62.58 65.70 0.77 0.78 0.78 0.83 0.88 0.81 0.91
November 11.07 11.41 12.57 9.00 10.16 10.84 7.10 19.84 7.68 11.85 11.51 6.30 11.44 0.87 0.68 0.30 0.41 0.27 0.47 0.37 1.09 2.80 2.70 2.79 2.55 3.02 2.77 2.53 0.05 0.06 0.06 0.07 0.04 0.06 0.02
50.08 61.10 47.55 66.71 37.48 52.59 32.40 20.63 6.24 11.56 6.13 4.35 9.78 0.29 0.37 0.15 0.21 0.07 0.15 0.19 0.38 61.31 61.61 63.05 63.60 65.11 62.93 65.84 0.77 0.79 0.79 0.85 0.89 0.82 0.91
10.69 10.77 9.73 10.08 10.32 10.32 6.76 15.27 9.43 11.24 7.21 10.39 10.71 0.64 0.70 0.25 0.36 0.09 0.39 0.36 0.64 2.86 2.63 3.04 2.48 2.87 2.78 2.43 0.06 0.05 0.07 0.08 0.04 0.06 0.02
December 48.18 61.63 46.76 65.89 38.64 52.22 30.95 21.43 6.28 10.96 7.55 3.84 10.01 0.38 0.27 0.20 0.22 0.08 0.12 0.18 0.52 61.43 61.54 63.45 64.07 65.38 63.17 66.11 0.76 0.78 0.77 0.83 0.87 0.80 0.90
9.82 10.59 10.99 9.38 10.01 10.16 5.80 15.18 7.51 10.24 8.84 6.16 9.59 1.14 0.56 0.53 0.53 0.14 0.25 0.40 1.19 2.75 2.67 2.63 2.38 2.79 2.64 2.32 0.06 0.06 0.07 0.07 0.05 0.06 0.03
January 53.82 65.18 49.38 68.48 40.38 55.45 31.62 20.85 6.06 10.36 6.88 3.55 9.54 0.22 0.26 0.30 0.25 0.18 0.11 0.22 0.52 61.51 61.72 63.54 64.56 65.41 63.35 66.47 0.76 0.76 0.75 0.82 0.86 0.79 0.89
February 10.03 11.10 11.94 10.71 11.09 10.98 6.90 14.20 6.92 9.11 6.09 4.38 8.14 0.54 0.71 0.59 0.67 0.53 0.28 0.56 0.97 2.81 2.60 2.64 2.49 2.91 2.69 2.22 0.06 0.05 0.06 0.05 0.04 0.05 0.03
52.48 62.51 49.46 68.42 41.86 54.95 32.01 19.54 6.40 10.34 5.93 4.12 9.27 0.42 0.27 0.23 0.39 0.14 0.11 0.23 0.58 61.54 61.70 63.61 64.62 65.59 63.88 66.87 0.76 0.77 0.76 0.83 0.87 0.80 0.89
11.18 12.33 12.44 11.36 11.24 11.71 7.75 14.14 6.67 9.10 6.38 5.37 8.33 0.81 0.46 0.54 0.74 0.32 0.31 0.47 1.05 2.75 2.64 2.60 2.48 2.72 2.61 2.17 0.06 0.05 0.06 0.06 0.04 0.05 0.03
March 52.47 62.04 50.75 68.12 42.02 55.08 32.94 22.80 8.76 14.01 8.27 4.71 11.71 0.58 0.36 0.22 0.17 0.10 0.07 0.19 0.49 61.74 61.93 63.90 64.82 66.15 63.71 67.28 0.83 0.76 0.75 0.81 0.86 0.79 0.89
April
11.60 12.54 13.30 9.98 22.21 13.92 7.68 17.97 9.55 12.80 8.06 6.48 10.91 2.04 0.78 0.47 0.32 0.15 0.15 0.38 0.81 2.74 2.42 2.70 2.43 2.67 2.59 2.16 0.07 0.05 0.06 0.07 0.05 0.06 0.03
53.95 63.42 50.63 68.59 39.74 55.27 33.56 25.33 9.22 16.33 9.00 5.44 13.06 0.8 0.21 0.16 0.20 0.15 0.05 0.16 0.30 61.32 61.63 63.22 64.20 65.86 63.25 67.41 0.75 0.76 0.75 0.81 0.86 0.79 0.90
11.57 13.84 12.74 11.55 12.49 12.44 6.66 22.56 10.27 16.17 10.33 8.33 13.53 0.27 0.33 0.38 0.45 0.44 0.08 0.34 0.57 2.79 2.50 2.73 2.63 2.52 2.64 2.08 0.06 0.06 0.07 0.07 0.05 0.06 0.03
0.19 0.36, December 0.18 0.40, January (2008) 0.22 0.56, February 0.23 0.47, March 0.19 0.38, April 0.16 0.34.
63.17 2.64, January February 63.88 2.61, April 63.25 2.64.
Seasonal variation in skin brightness The inner forearm showed the highest value in 6 test sites (Table 2). The brightness in the inner forearm was significantly higher when compared with other test sites (P < 0.05). There was a monthly variation in skin brightness, the brightness of face from April 2007 to 2008 ranged from 62.58 2.77 to 64.14 3.29 (Table 2 and Fig. 1). The mean of L* value for the skin brightness for thirteen months were; April (2007) 63.54 2.64, May 64.14 3.29, June 63.54 2.55, July 63.31 2.63, August 62.90 2.57, September 63.30 2.70, October 62.58 2.77, November 62.93 2.78, December
Seasonal variation in skin elasticity The inner forearm showed the highest value in 6 test sites (Table 2). The brightness in the inner forearm was significantly higher when compared with other test sites (P < 0.05). There was a monthly variation in skin brightness, the brightness of face from April 2007 to 2008 ranged from 0.79 0.06 to 0.83 0.06 (Table 2 and Fig. 1). The mean value of skin elasticity for thirteen months were; April (2007) 0.82 0.07, May 0.82 0.07, June 0.83 0.07, July 0.81 0.06, August 0.80 0.07, September 0.83 0.06, October 0.81 0.06, November 0.82 0.06, December 0.80 0.06, January
(2008) March
63.35 2.69, 63.71 2.59,
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Nam et al. (d)
70
(a)
Brightness (L* value)
Hydration (A.U.)
60 50 40 30 20 10 0
4
5
6
7
8
9
10 11 12
1
2
3
4
69 68 67 66 65 64 63 62 61 60 59
4
5
6
Month (from 2007 to 2008)
Elasticity (R2 value)
16
Sebum (μg/cm2)
8
9
10 11 12
1
2
3
4
(e) 0.95
18
(b)
7
Month (from 2007 to 2008)
14 12 10 8 6 4
0.90 0.85 0.80 0.75
2 0
4
5
6
7
8
9
10 11 12
1
2
3
4
Month (from 2007 to 2008)
0.70
4
5
6
7
8
9
10 11 12
1
2
3
4
Month (from 2007 to 2008)
(c) 0.70
Scaliness (%)
0.60 0.50 0.40 0.30 0.20 0.10 0.00
4
5
6
7
8
9
10 11 12
1
2
3
4
Month (from 2007 to 2008) Fig. 1. Seasonal changes of skin physiology, (a) hydration, (b) sebum, (c) scaliness, (d) brightness and (e) elasticity on facial skin for 13 months. Face, Inner forearm.
(2008) 0.79 0.05, February 0.80 0.05, March 0.79 0.06, April 0.79 0.06. Correlation analysis To study the changes involved in the skin depending on the air temperature change, Pearson correlation (r) was examined. The result is shown in Table 3. Statistical difference was found between the environmental factors. There was statistical correlation between air tempera-
6
ture and three environmental factors such as relative humidity (r = 0.804, P = 0.001), air pressure (r = 0.922, P < 0.001), highest precipitation (r = 0.765, P = 0.002). Comparing the skin biophysical parameters in the face, there was a negative correlation between skin scaliness and three environmental factors such as air temperature, relative humidity and highest precipitation. There was a positive correlation between skin scaliness and two environmental factors such as air pressure and duration of sunshine.
Seasonal variation in skin biophysical parameters TABLE 3. Correlation coefficients between the climate factors and skin physiology of the face
Air temperature Relative humidity Air pressure Duration of sunshine Highest precipitation Hydration Sebum Scaliness Brightness Elasticity
Air temperature
Relative humidity
1
0.804** 1
Air pressure 0.922** 0.717** 1
Duration of sunshine 0.551 0.890** 0.465 1
Highest precipitation
Hydration
Sebum
Scaliness
Brightness
Elasticity
0.765** 0.797** 0.830** 0.624*
0.308 0.381 0.181 0.415
0.367 0.155 0.381 0.040
0.934** 0.843** 0.891** 0.646*
0.102 0.308 0.243 0.431
0.611* 0.438 0.567* 0.200
1
0.233
0.379
0.719**
0.115
0.424
1
0.416 1
0.437 0.089 1
0.391 0.134 0.130 1
0.376 0.300 0.493 0.096 1
*P < 0.05; **P < 0.01.
Elasticity was correlated with air temperature positively and with air pressure negatively.
Discussion The primary objective of this study was to quantitatively measure the seasonal variation in skin properties. Sang Woong Youn et al. conducted a similar study performed in the same country. Here, 46 female Korean volunteers were recruited and facial sebum secretion at five different sites of the face was reported to look at seasonal variation (14). We took a different approach to investigate annual variations of additional skin properties such as skin hydration, sebum, scaliness, brightness, and elasticity. Facial sebum secretions showed definitive seasonal differences. Sang Woong Youn et al. found that summer was the only season showing a significantly higher level of sebum secretion and stated that the T zone and U zone exhibited a higher secretion rate of sebum in summer than in spring, or fall. In this study, high sebum secretion was observed in April, May, September, and October. However, for the months of January and February, the sebum secretion rate was low. The low sebum secretion rate in the winter is explainable as this result is similar to those of previous studies. To conclude that there is a higher sebum secretion in spring and winter compared with summer, further study is needed. Skin brightness is directly related to amount of exposure to sunlight. It is widely known that when exposure to the sunlight increases, especially during summer days, the skin darkens. However, skin color is darkest in the month of
October. In our study, for the months of May 2007 and March 2008, the skin color was light. The same study result was found by Lee et al. (14). In addition, skin redness and yellowness was affected by specific months of the year. This result can be expected as the skin is exposed to a lot of sunlight in the summer. However, in the winter, it can occur due to dry the atmosphere and flushing of skin. Skin elasticity decreased for the months of January to April compared with other months. A correlation was shown between air temperature and skin elasticity. Skin elasticity in the winter is low compared to other seasons. In addition, as the average temperature rises, skin elasticity drops. However, as skin elasticity is directly related to age, age should be considered whenever skin elasticity is studied. There was a correlation between environmental factors and changes in the skin’s biophysical parameters. There was a negative correlation between hydration level in the face and skin scaling. It is widely known that as the hydration level in the skin increases, there is a concomitant decrease in skin scaling. This study indirectly proved that there are changes in the hydration level or skin scaling due to environmental factors, such as relative humidity. The skin is readily irritated or stimulated by external factors. There was a correlation between sebum secretion levels in the skin and skin elasticity. An increase in the sebum secretion contributed to an augmentation in the skin softness and elasticity. There are more sebum secretions in the forehead than in the cheek. Therefore, since the sebum secretion in the cheek occurs in a miniscule amount, we can
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predict no significant correlation regarding the sebum secretion in the cheek. There was no correlation between skin hydration levels with skin elasticity. In the dermis, collagen mostly contributes to skin elasticity. The hydration level of the skin relates to the hydration level of the epidermis layer. Therefore, hydration of the epidermis does not increase the elasticity of the dermis layer of the skin. However, as the hydration level in the skin decreases, there is an increase in skin scaling. Increased skin scaling contributes to
References 1. Wilhelm KP, Cua AB, Maibach HI. Skin aging. Effect on transepidermal water loss, stratum corneum hydration, skin surface pH, and casual sebum content. Arch Dermatol 1991; 127: 1806–1809. 2. Man MQ, Xin SJ, Song SP, Cho SY, Zhang XJ, Tu CX, Feingold KR, Elias PM. Variation of skin surface pH, sebum content and stratum corneum hydration with age and gender in a large Chinese population. Skin Pharmacol Physiol 2009; 22: 190–199. 3. Ezure T, Yagi E, Kunizawa N, Hirao T, Amano S. Comparison of sagging at the cheek and lower eyelid between male and female faces. Skin Res Technol 2011; 17: 510–515. 4. Marrakchi S, Maibach HI. Biophysical parameters of skin: map of human face, regional, and agerelated differences. Contact Dermatitis 2007; 57: 28–34. 5. Yun IS, Lee WJ, Rah DK, Kim YO, Park BY. Skin color analysis using a spectrophotometer in Asians. Skin Res Technol 2010; 16: 311–315. 6. Han K, Choi T, Son D. Skin color of Koreans: statistical evaluation of affecting factors. Skin Res Technol 2006; 12: 170–177.
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rigidity of the skin, thereby decreasing the skin elasticity. Such a result was found for the cheek. In conclusion, we showed that scaliness on facial skin was highly correlated with environmental factors, such as air temperature, relative humidity, and highest precipitation negatively and air pressure and duration of sunshine positively. The correlations shown between the skin biophysical parameters and environmental factors demonstrate that the skin is continuously influenced by surrounding factors.
7. Lee MR, Nam GW, Jung YC, Park SY, Han JY, Cho JC, Suh KD, Hwang JK. Comparison of the skin biophysical parameters of Southeast Asia females: forehead-cheek and ethnic groups. J Eur Acad Dermatol Venereol 2013; 27: 1521– 1526. 8. Jung YC, Kim EJ, Cho JC, Suh KD, Nam GW. Effect of skin pH for wrinkle formation on Asian: Korean, Vietnamese and Singaporean. J Eur Acad Dermatol Venereol 2013; 27: e328–e332. 9. Nouveau-Richard S, Zhu W, Li YH et al. Oily skin: specific features in Chinese women. Skin Res Technol 2007; 13: 43–48. 10. Hillebrand GG, Miyamoto K, Schnell B, Ichihashi M, Shinkura R, Akiba S. Quantitative evaluation of skin condition in an epidemiological survey of females living in northern versus southern Japan. J Dermatol Sci 2001; 27(Suppl 1): S42–S52. 11. Qiu H, Long X, Ye JC et al. Influence of season on some skin properties: winter vs. summer, as experienced by 354 Shanghaiese women of various ages. Int J Cosmet Sci 2011; 33: 377–383. 12. Roh K, Kim D, Ha S, Ro Y, Kim J, Lee H. Pigmentation in Koreans: study of the differences from
caucasians in age, gender and seasonal variations. Br J Dermatol 2001; 144: 94–99. 13. Abe T, Mayuzumi J, Kikuchi N, Arai S. Seasonal variations in skin temperature, skin pH, evaporative water loss and skin surface lipid values on human skin. Chem Pharm Bull (Tokyo) 1980; 28: 387– 392. 14. Youn SW, Na JI, Choi SY, Huh CH, Park KC. Regional and seasonal variations in facial sebum secretions: a proposal for the definition of combination skin type. Skin Res Technol 2005; 11: 189– 195. 15. Tsukahara K, Osanai O, Kitahara T, Takema Y. Seasonal and annual variation in the intensity of facial wrinkles. Skin Res Technol 2013; 19: 279–287. Address: Jae-Kwan Hwang Department of Biomaterials Scienceand Engineering & Department of Biotechnology Yonsei University, 50 Yonsei-ro Seodaemun-gu, Seoul 120-749 Korea Tel: +82 2 2123 5881 Fax: +82 2 362 7265 e-mail: [email protected]
© 2014 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd Skin Research and Technology
The seasonal variation in skin hydration, sebum, scaliness, brightness and elasticity in Korean females G. W. Nam1, J. H. Baek2, J. S. Koh2 and J.-K. Hwang3 1
2
Skin Research Institute, Amorepacific R&D Center, Seoul, Korea, Dermapro Skin Research Center, DERMAPRO LTD., Seoul, Korea and 3Department of Biomaterials Science and Engineering, Yonsei University, Seoul, Korea
Background/purpose: Age, gender, regional, and ethnic differences influence skin conditions. The purpose of this study was to observe the effects of environments, especially the air temperature, relative humidity, air pressure, duration of sunshine, and precipitation on skin, and the seasonal variation in skin hydration, sebum, scales, brightness, and elasticity in Korean females. Methods: The study included 89 Korean subjects, aged 29.7 6.2 years. The five skin biophysical parameters (skin hydration, sebum, scales, brightness, and elasticity) were measured at six sites: forehead, under the eye, frontal cheek, crow’s foot, lateral cheek, and inner forearm. Skin hydration was measured using the Corneometerâ CM 825. Skin sebum was measured with Sebumeterâ SM 815. Skin scaliness was measured with Visioscanâ VC 98. Skin brightness (L* value) was measured by using Spectrophotometer. A suction chamber device, Cutometerâ MPA 580, was used to measure the skin elasticity. The measurements were performed every month for 13 months, from April 2007 to April 2008. Results: There were significantly seasonal variations in environmental factors. The air temperature was the lowest in
January ( 1.7°C), and the highest in August (26.5°C). The relative humidity was the lowest in February (46%), and the highest in July and August (75%). There was a negative correlation between skin scaliness and three environmental factors such as air temperature, relative humidity, and highest precipitation. There was a positive correlation between skin scaliness and two environmental factors such as air pressure and duration of sunshine. Elasticity was correlated with air temperature positively and with air pressure negatively. Conclusion: The correlations shown between the skin biophysical parameters and environmental factors demonstrate that the skin biophysical parameters are affected by environmental factors.
and extrinsic factors, such as age, gender, and regional and ethnic difference affect the skin’s physiological and biophysical parameters. Previously, age-dependent decreases of transepidermal water loss, stratum corneum (SC) hydration on the forehead, dermal elasticity of the facial skin, and sebum content of nasolabial area have been reported (1–4). Skin surface pH on the forehead of old people is higher than that in young people (2). In the reports concerning gender differences related with the skin, the melanin and erythema indexes are higher and sagging at the lower eyelid is more severe in men than in women
(3, 5, 6). Many reports on ethnic and regional differences in skin properties have also been published (7–10). However, atmospheric condition and climate is an important factor influencing the skin physiology. Qiu et al. reported that skin hydration and density for hyper-pigmented spots increased in summer as compared with winter season (11). Roh et al. also showed that several regions (V-neck and dorsal forearm) of the body have increased pigmentation in summer (12). Abe et al. studied the seasonal variation (four different seasons) of skin temperature, skin pH, evaporative water loss (EWL), and skin surface lipid of the forearm in a Japanese population. They found that TEWL and lipid values in July (summer) were approximately two to three times those in January
V
ARIOUS INTRINSIC
First two authors contributed equally to this work.
Key words: skin – seasonal variations – Korean female – non-invasive
Ó 2014 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd Accepted for publication 5 January 2014
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Nam et al.
(winter), April (spring), or October (fall), and that skin pH in July (summer) was significantly lower than January (winter) (13). Youn et al. reported definitive regional and seasonal variations in sebum secretion (14). Tsukahara et al. also showed seasonal environmental changes affected eye wrinkle depth (15). The aim of this study was to observe the annual variations of sebum, hydration, scale, skin color, and elasticity in Korean females and the correlation between annual variations of them and environment changes of air temperature, relative humidity, air pressure, duration of sunshine, and precipitation.
Material and Methods Acquisition of climate information Climate data were collected from ‘Annual climatological report’ published by Korea meteorological administration. Daily mean values of air temperature were computed from the 3-hourly observations measured at 03, 06, 09, 12, 15, 18, 21, and 24 h. One-day greatest value is the largest amounts of precipitation measured in a day. Evaporation is measured from 09 h to 09 h of the following day. The duration of sunshine is measured by a rotating-type sunshine recorder.
Subjects and study design The study was conducted according to the principles of the Declaration of Helsinki. Volunteers gave written informed consent to participate in the study. In total, one hundred and fifty-one healthy female volunteers (aged 20–39 years) were enrolled for this study in the beginning. Following were exclusion criteria, (i) pregnant woman and women scheduled to be pregnant (ii) infectious skin disease patients (iii) received anti-immunologic therapy within 3 month. (iv) used steroid drugs within 1 month (v) serious kidney or liver disease patients (vi) diabetes, hypertension, or asthma patients (vii) atopic patients (viii) have severe allergy to cosmetics or drugs (ix) have lesions on measurement site (x) is incapable of giving informed consent. Thirteen months later, eighty-nine healthy female volunteers, aged 29.7 6.2 years (20–38 years) remained. The female volunteers were consisted of thirty-nine females of 20s (aged 23.4 2.8 years) and fifty females of 30s (aged 34.7 2.2 years).
2
All volunteers lived in Seoul (north latitude 37.34, east longitude 126.57). The measurements were performed every month for 13 months, from April 2007 to April 2008. Volunteers were allowed to relax in the room maintained at a temperature of 22 2°C and a relative humidity of 50 5% for 20 min, after washing their face and arms with cleanser. The five skin biophysical parameters (skin hydration, skin sebum, skin scaliness, skin color, and skin elasticity) were measured at six sites: forehead, under the eye, frontal cheek, crow’s foot, lateral cheek, and inner forearm. All measurements, except for skin elasticity, sebum, and skin scaling, were measured 3 times. In addition, the average data were used for the data analysis.
Measurement of skin hydration The skin hydration in the stratum corneum was measured with a Corneometer CM825 (Courage1Khazaka Electronic GmbH, Cologne, Germany) based on a capacitance measurement. We measured the capacitance value three times, and the averages of the values were water contents.
Measurement of sebum secretion Measurements of sebum were performed with the Sebumeterâ SM 815 (Courage & Khazaka Electronic GmbH, Cologne, Germany). It is a direct measurement of the sebum secretion on skin. The measurement principle is the photometric method, the grease spot photometer. A microprocessor calculates the result, which is shown on the display in lg sebum/cm2 of the skin. Each value was the average of three measurements. Measurement of skin scaliness Skin scaliness was measured Visioscanâ VC 98 (Courage & Khazaka, Cologne, Germany). It is a special UVA-light video camera with high resolution. The scaliness parameter was analyzed with the software.
Measurement of skin brightness Skin brightness was measured using a spectrophotometer CM-2500D (Konica Minolta, Inc., Tokyo, Japan). The melanin and erythema
Seasonal variation in skin biophysical parameters
indexes, CIE L*a*b* color coordinates, and the Munsell value (hue, value, and chroma) could be shown almost at the same time as the measurement, and the results were presented with graphs on the screen. We measured L* value for skin brightness three times, and calculated the averages of the triplicates.
Measurement of skin elasticity Skin elasticity was measured by Cutometer MPA 580â (Courage & Khazaka, Cologne, Germany). Subjects lay on a bed and inclined their face at an angle of 45° to reduce the effect of gravity on the measured values of dermal elasticity and subcutaneous adipose mass. Using a 2-mm probe, a negative pressure of 450 mbar was applied to the skin for a period of 2 s, followed by a 2 s relaxation time. The skin elasticity was analyzed R2 {Ua/Uf: gloss elasticity, Portion between the max. amplitude and the ability of re-deformation of the skin (gross elasticity), the closer the value is to 1 (100%), the more elastic the curve}.
Statistics The collected data were analyzed using SPSS (version 19.0; SPSS Inc., Chicago, IL, USA). To compare the measurement time points, RM-ANOVA tests were used. In addition, correlations between climate conditions and physiology parameters of facial skin were calculated using Pearson’s correlation coefficient.
Results Climate variations Table 1 shows the data for air temperature, relative humidity, air pressure, duration of sunshine, and highest precipitation. The air temperature was the lowest in January ( 1.7°C), and the highest in August (26.5°C). The relative humidity was the lowest in February (46%), and the highest in July and August (75%). The air pressure was the lowest in July (994.7 hPa), and the highest in January (1,015.5 hPa). The duration of sunshine was the lowest in September (85.1 h), and the highest in April 2008 (208.1 h). The highest precipitation was the lowest in December (2.5 mm), and the highest in July (76.0 mm).
Seasonal variation in skin hydration The crow’s foot showed the highest value in 6 test sites (Table 2). Skin hydration in the crow’s foot was significantly higher when compared with the inner forearm and lateral cheek (P < 0.05). There was a clear seasonal variation in skin hydration, the skin hydration level of face from April 2007 to 2008 ranged from 49.48 12.23 to 57.18 11.38 (Table 2 and Fig. 1a). The mean value (arbitrary unit) of skin hydration for thirteen months were; April (2007) 49.48 12.23, May 52.19 11.96, June 54.61 11.76, July 56.00 11.67, August 57.18 11.38, September 55.44 10.85, October 55.39 10.84, November 52.59 10.32, December 52.22
TABLE 1. Climate information of study region (Seoul, South Korea) for 13 months 2007 Year Month
4
2008 5
Air temperature(°C) Mean 11.4 18.1 Maximum 22.6 30.1 Minimum 1.6 9.0 Relative humidity (%) Mean 53 62 Lowest 14 17 Air pressure (0.1 hPa) Mean 10,056 9,978 Highest 10,281 10,188 Lowest 10,059 9,898 Duration of sunshine (0.1 hr) Total 1,918 1,973 Highest precipitation (0.1 mm/day) Mean 260 490
6
7
8
9
10
11
12
1
2
3
4
23.2 33.2 14.1
24.2 31.2 17.7
26.5 33.2 19.8
21.5 31.1 14.1
15.1 26.2 3.2
6.7 19.3 5.5
1.8 13.8 7.4
7.3 19.8 1.7
14.1 28 3.8
61 13
75 35
75 23
74 36
63 13
55 16
60 24
50 13
46 12
56 10
50 11
9,985 10,139 9,986
9,947 10,121 9,957
9,987 10,169 9,969
10,025 10,229 10,037
10,094 10,273 10,102
10,132 10,343 10,146
10,118 10,347 10,111
10,155 10,389 10,151
10,142 10,381 10,043
10,079 10,292 10,053
10,050 10,224 10,041
1,752
915
1,057
851
1,709
1,885
1,408
1,665
2,242
1,873
2,081
220
760
420
485
220
150
25
67
74
275
115
1.7 7.3 11.1
1.2 10.5 10.1
3
Nam et al. TABLE 2. Monthly variations of hydration, sebum, scaliness, brightness, and elasticity in Korean females (N = 89) Time 2007 Parameter
Test site
April
Hydration
Forehead Under the eye Frontal cheek Crow’s foot Lateral cheek Face Inner forearm Forehead Under the eye Frontal cheek Crow’s foot Lateral cheek Face Inner forearm Forehead Under the eye Frontal cheek Crow’s foot Lateral cheek Face Inner forearm Forehead Under the eye Frontal cheek Crow’s foot Lateral cheek Face Inner forearm Forehead Under the eye Frontal cheek Crow’s foot Lateral cheek Face Inner forearm
49.35 55.69 45.23 62.89 34.24 49.48 31.00 38.40 8.35 21.3 9.67 5.52 16.66 0.93 0.16 0.09 0.29 0.09 0.36 0.20 0.58 61.82 62.53 63.55 63.53 66.29 63.54 67.32 0.79 0.79 0.77 0.84 0.89 0.82 0.92
Sebum
Scaliness
Brightness
Elasticity
May
9.96 13.80 13.38 11.68 12.34 12.23 7.87 22.73 8.85 15.08 11.07 6.79 12.90 2.09 0.33 0.17 1.13 0.22 1.50 0.67 1.20 2.66 2.49 2.69 2.53 2.84 2.64 2.25 0.08 0.07 0.08 0.09 0.05 0.07 0.03
50.66 59.34 48.05 64.27 38.65 52.19 32.20 29.82 7.92 15.98 7.33 4.21 13.05 0.36 0.26 0.14 0.12 0.14 0.07 0.14 0.45 62.43 62.40 64.90 64.46 66.54 64.14 68.04 0.78 0.80 0.79 0.85 0.90 0.82 0.93
June
11.80 12.75 12.71 12.00 10.54 11.96 7.18 23.92 8.99 13.38 7.32 6.38 12.00 0.73 0.75 0.39 0.32 0.64 0.11 0.44 1.23 3.22 3.35 3.60 2.98 3.31 3.29 2.79 0.09 0.07 0.08 0.07 0.04 0.07 0.02
10.16, January (2008) 55.45 10.98, February 54.95 11.71, March 55.08 13.92, April 55.27 12.44. Seasonal variation in sebum secretion The forehead showed the highest value in 6 test sites (Table 2). Sebum secretion in the forehead was significantly higher when compared with the inner forearm, under the eye and crow’s foot (P < 0.05). There was a clear monthly variation in sebum secretion for forehead and frontal cheek, the sebum secretion of face from April 2007 to 2008 ranged from 9.27 8.33 to 16.66 12.90 (Table 2 and Fig. 1). The mean value (lg/cm2) of sebum secretion for thirteen months were; April (2007) 16.66 12.90, May 13.05 12.00, June 9.85 10.21, July 11.88 11.51, August 8.10 8.18, September
4
July
54.16 60.68 51.49 68.22 38.48 54.61 32.80 23.02 5.19 11.43 6.34 3.28 9.85 0.27 0.15 0.08 0.12 0.04 0.08 0.10 0.17 61.79 62.27 63.86 63.85 65.93 63.54 67.05 0.79 0.80 0.80 0.85 0.90 0.83 0.92
11.06 12.06 13.05 10.30 12.30 11.76 6.42 18.30 6.93 9.98 11.37 4.44 10.21 0.78 0.45 0.25 0.36 0.07 0.24 0.27 0.35 2.79 2.34 2.94 2.22 2.55 2.55 2.33 0.08 0.07 0.07 0.07 0.05 0.07 0.03
55.31 65.48 51.91 69.32 37.96 56.00 34.57 25.03 8.09 13.96 8.33 4.01 11.88 0.56 0.08 0.08 0.11 0.05 0.06 0.08 0.09 61.39 61.81 63.98 63.66 65.70 63.31 66.37 0.79 0.77 0.79 0.83 0.88 0.81 0.91
August
11.25 13.06 12.47 10.52 11.03 11.67 6.08 19.08 10.14 15.26 7.82 5.24 11.51 1.04 0.16 0.18 0.30 0.11 0.11 0.17 0.25 2.86 2.35 2.73 2.44 2.79 2.63 2.37 0.07 0.07 0.06 0.07 0.05 0.06 0.02
56.42 65.48 54.95 68.65 40.40 57.18 34.80 23.47 6.64 14.37 6.96 4.43 8.10 0.39 0.06 0.12 0.08 0.05 0.08 0.08 0.17 61.22 61.60 63.62 62.88 65.15 62.90 65.80 0.77 0.77 0.78 0.83 0.87 0.80 0.91
September 10.51 11.85 13.31 10.01 11.21 11.38 5.53 17.89 6.94 11.41 7.82 6.56 8.18 0.78 0.15 0.29 0.17 0.07 0.13 0.16 0.54 2.73 2.38 2.78 2.41 2.55 2.57 2.50 0.08 0.07 0.08 0.08 0.04 0.07 0.03
53.87 63.91 52.15 67.97 39.31 55.44 32.52 30.16 7.51 15.83 8.08 5.19 13.35 0.34 0.25 0.09 0.15 0.09 0.09 0.13 0.27 61.32 61.70 63.47 62.87 65.16 63.30 65.54 0.79 0.78 0.78 0.83 0.88 0.83 0.91
12.11 11.27 10.74 9.67 10.43 10.85 5.19 26.87 11.06 14.67 12.12 7.92 14.53 0.74 1.15 0.20 0.49 0.14 0.23 0.44 0.67 2.68 2.68 2.60 2.50 3.01 2.70 2.39 0.07 0.06 0.06 0.07 0.04 0.06 0.02
13.35 14.53, October 12.46 11.44, November 9.78 10.71, December 10.01 9.59, January (2008) 9.54 8.14, February 9.27 8.33, March 11.71 10.91, April 13.06 13.53. Seasonal variation in skin scaliness The forehead showed the highest value in 6 test sites (Table 2). Skin scaliness in the forehead was significantly higher when compared with other test sites (P < 0.05). There was a clear monthly variation in sebum scaliness for forehead, the skin scaliness of face from April 2007 to 2008 ranged from 0.08 0.17 to 0.22 0.56 (Table 2 and Fig. 1). The mean value (%) of skin scaliness for thirteen months were; April (2007) 0.20 0.67, May 0.14 0.44, June 0.10 0.27, July 0.08 0.17, August 0.08 0.16, September 0.13 0.44, October 0.12 0.37, November
Seasonal variation in skin biophysical parameters
2008 October 52.45 62.68 50.43 69.16 42.24 55.39 33.51 27.22 7.66 13.78 8.852 4.80 12.46 0.53 0.25 0.13 0.16 0.10 0.14 0.12 0.49 61.25 60.92 63.07 63.08 64.56 62.58 65.70 0.77 0.78 0.78 0.83 0.88 0.81 0.91
November 11.07 11.41 12.57 9.00 10.16 10.84 7.10 19.84 7.68 11.85 11.51 6.30 11.44 0.87 0.68 0.30 0.41 0.27 0.47 0.37 1.09 2.80 2.70 2.79 2.55 3.02 2.77 2.53 0.05 0.06 0.06 0.07 0.04 0.06 0.02
50.08 61.10 47.55 66.71 37.48 52.59 32.40 20.63 6.24 11.56 6.13 4.35 9.78 0.29 0.37 0.15 0.21 0.07 0.15 0.19 0.38 61.31 61.61 63.05 63.60 65.11 62.93 65.84 0.77 0.79 0.79 0.85 0.89 0.82 0.91
10.69 10.77 9.73 10.08 10.32 10.32 6.76 15.27 9.43 11.24 7.21 10.39 10.71 0.64 0.70 0.25 0.36 0.09 0.39 0.36 0.64 2.86 2.63 3.04 2.48 2.87 2.78 2.43 0.06 0.05 0.07 0.08 0.04 0.06 0.02
December 48.18 61.63 46.76 65.89 38.64 52.22 30.95 21.43 6.28 10.96 7.55 3.84 10.01 0.38 0.27 0.20 0.22 0.08 0.12 0.18 0.52 61.43 61.54 63.45 64.07 65.38 63.17 66.11 0.76 0.78 0.77 0.83 0.87 0.80 0.90
9.82 10.59 10.99 9.38 10.01 10.16 5.80 15.18 7.51 10.24 8.84 6.16 9.59 1.14 0.56 0.53 0.53 0.14 0.25 0.40 1.19 2.75 2.67 2.63 2.38 2.79 2.64 2.32 0.06 0.06 0.07 0.07 0.05 0.06 0.03
January 53.82 65.18 49.38 68.48 40.38 55.45 31.62 20.85 6.06 10.36 6.88 3.55 9.54 0.22 0.26 0.30 0.25 0.18 0.11 0.22 0.52 61.51 61.72 63.54 64.56 65.41 63.35 66.47 0.76 0.76 0.75 0.82 0.86 0.79 0.89
February 10.03 11.10 11.94 10.71 11.09 10.98 6.90 14.20 6.92 9.11 6.09 4.38 8.14 0.54 0.71 0.59 0.67 0.53 0.28 0.56 0.97 2.81 2.60 2.64 2.49 2.91 2.69 2.22 0.06 0.05 0.06 0.05 0.04 0.05 0.03
52.48 62.51 49.46 68.42 41.86 54.95 32.01 19.54 6.40 10.34 5.93 4.12 9.27 0.42 0.27 0.23 0.39 0.14 0.11 0.23 0.58 61.54 61.70 63.61 64.62 65.59 63.88 66.87 0.76 0.77 0.76 0.83 0.87 0.80 0.89
11.18 12.33 12.44 11.36 11.24 11.71 7.75 14.14 6.67 9.10 6.38 5.37 8.33 0.81 0.46 0.54 0.74 0.32 0.31 0.47 1.05 2.75 2.64 2.60 2.48 2.72 2.61 2.17 0.06 0.05 0.06 0.06 0.04 0.05 0.03
March 52.47 62.04 50.75 68.12 42.02 55.08 32.94 22.80 8.76 14.01 8.27 4.71 11.71 0.58 0.36 0.22 0.17 0.10 0.07 0.19 0.49 61.74 61.93 63.90 64.82 66.15 63.71 67.28 0.83 0.76 0.75 0.81 0.86 0.79 0.89
April
11.60 12.54 13.30 9.98 22.21 13.92 7.68 17.97 9.55 12.80 8.06 6.48 10.91 2.04 0.78 0.47 0.32 0.15 0.15 0.38 0.81 2.74 2.42 2.70 2.43 2.67 2.59 2.16 0.07 0.05 0.06 0.07 0.05 0.06 0.03
53.95 63.42 50.63 68.59 39.74 55.27 33.56 25.33 9.22 16.33 9.00 5.44 13.06 0.8 0.21 0.16 0.20 0.15 0.05 0.16 0.30 61.32 61.63 63.22 64.20 65.86 63.25 67.41 0.75 0.76 0.75 0.81 0.86 0.79 0.90
11.57 13.84 12.74 11.55 12.49 12.44 6.66 22.56 10.27 16.17 10.33 8.33 13.53 0.27 0.33 0.38 0.45 0.44 0.08 0.34 0.57 2.79 2.50 2.73 2.63 2.52 2.64 2.08 0.06 0.06 0.07 0.07 0.05 0.06 0.03
0.19 0.36, December 0.18 0.40, January (2008) 0.22 0.56, February 0.23 0.47, March 0.19 0.38, April 0.16 0.34.
63.17 2.64, January February 63.88 2.61, April 63.25 2.64.
Seasonal variation in skin brightness The inner forearm showed the highest value in 6 test sites (Table 2). The brightness in the inner forearm was significantly higher when compared with other test sites (P < 0.05). There was a monthly variation in skin brightness, the brightness of face from April 2007 to 2008 ranged from 62.58 2.77 to 64.14 3.29 (Table 2 and Fig. 1). The mean of L* value for the skin brightness for thirteen months were; April (2007) 63.54 2.64, May 64.14 3.29, June 63.54 2.55, July 63.31 2.63, August 62.90 2.57, September 63.30 2.70, October 62.58 2.77, November 62.93 2.78, December
Seasonal variation in skin elasticity The inner forearm showed the highest value in 6 test sites (Table 2). The brightness in the inner forearm was significantly higher when compared with other test sites (P < 0.05). There was a monthly variation in skin brightness, the brightness of face from April 2007 to 2008 ranged from 0.79 0.06 to 0.83 0.06 (Table 2 and Fig. 1). The mean value of skin elasticity for thirteen months were; April (2007) 0.82 0.07, May 0.82 0.07, June 0.83 0.07, July 0.81 0.06, August 0.80 0.07, September 0.83 0.06, October 0.81 0.06, November 0.82 0.06, December 0.80 0.06, January
(2008) March
63.35 2.69, 63.71 2.59,
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Nam et al. (d)
70
(a)
Brightness (L* value)
Hydration (A.U.)
60 50 40 30 20 10 0
4
5
6
7
8
9
10 11 12
1
2
3
4
69 68 67 66 65 64 63 62 61 60 59
4
5
6
Month (from 2007 to 2008)
Elasticity (R2 value)
16
Sebum (μg/cm2)
8
9
10 11 12
1
2
3
4
(e) 0.95
18
(b)
7
Month (from 2007 to 2008)
14 12 10 8 6 4
0.90 0.85 0.80 0.75
2 0
4
5
6
7
8
9
10 11 12
1
2
3
4
Month (from 2007 to 2008)
0.70
4
5
6
7
8
9
10 11 12
1
2
3
4
Month (from 2007 to 2008)
(c) 0.70
Scaliness (%)
0.60 0.50 0.40 0.30 0.20 0.10 0.00
4
5
6
7
8
9
10 11 12
1
2
3
4
Month (from 2007 to 2008) Fig. 1. Seasonal changes of skin physiology, (a) hydration, (b) sebum, (c) scaliness, (d) brightness and (e) elasticity on facial skin for 13 months. Face, Inner forearm.
(2008) 0.79 0.05, February 0.80 0.05, March 0.79 0.06, April 0.79 0.06. Correlation analysis To study the changes involved in the skin depending on the air temperature change, Pearson correlation (r) was examined. The result is shown in Table 3. Statistical difference was found between the environmental factors. There was statistical correlation between air tempera-
6
ture and three environmental factors such as relative humidity (r = 0.804, P = 0.001), air pressure (r = 0.922, P < 0.001), highest precipitation (r = 0.765, P = 0.002). Comparing the skin biophysical parameters in the face, there was a negative correlation between skin scaliness and three environmental factors such as air temperature, relative humidity and highest precipitation. There was a positive correlation between skin scaliness and two environmental factors such as air pressure and duration of sunshine.
Seasonal variation in skin biophysical parameters TABLE 3. Correlation coefficients between the climate factors and skin physiology of the face
Air temperature Relative humidity Air pressure Duration of sunshine Highest precipitation Hydration Sebum Scaliness Brightness Elasticity
Air temperature
Relative humidity
1
0.804** 1
Air pressure 0.922** 0.717** 1
Duration of sunshine 0.551 0.890** 0.465 1
Highest precipitation
Hydration
Sebum
Scaliness
Brightness
Elasticity
0.765** 0.797** 0.830** 0.624*
0.308 0.381 0.181 0.415
0.367 0.155 0.381 0.040
0.934** 0.843** 0.891** 0.646*
0.102 0.308 0.243 0.431
0.611* 0.438 0.567* 0.200
1
0.233
0.379
0.719**
0.115
0.424
1
0.416 1
0.437 0.089 1
0.391 0.134 0.130 1
0.376 0.300 0.493 0.096 1
*P < 0.05; **P < 0.01.
Elasticity was correlated with air temperature positively and with air pressure negatively.
Discussion The primary objective of this study was to quantitatively measure the seasonal variation in skin properties. Sang Woong Youn et al. conducted a similar study performed in the same country. Here, 46 female Korean volunteers were recruited and facial sebum secretion at five different sites of the face was reported to look at seasonal variation (14). We took a different approach to investigate annual variations of additional skin properties such as skin hydration, sebum, scaliness, brightness, and elasticity. Facial sebum secretions showed definitive seasonal differences. Sang Woong Youn et al. found that summer was the only season showing a significantly higher level of sebum secretion and stated that the T zone and U zone exhibited a higher secretion rate of sebum in summer than in spring, or fall. In this study, high sebum secretion was observed in April, May, September, and October. However, for the months of January and February, the sebum secretion rate was low. The low sebum secretion rate in the winter is explainable as this result is similar to those of previous studies. To conclude that there is a higher sebum secretion in spring and winter compared with summer, further study is needed. Skin brightness is directly related to amount of exposure to sunlight. It is widely known that when exposure to the sunlight increases, especially during summer days, the skin darkens. However, skin color is darkest in the month of
October. In our study, for the months of May 2007 and March 2008, the skin color was light. The same study result was found by Lee et al. (14). In addition, skin redness and yellowness was affected by specific months of the year. This result can be expected as the skin is exposed to a lot of sunlight in the summer. However, in the winter, it can occur due to dry the atmosphere and flushing of skin. Skin elasticity decreased for the months of January to April compared with other months. A correlation was shown between air temperature and skin elasticity. Skin elasticity in the winter is low compared to other seasons. In addition, as the average temperature rises, skin elasticity drops. However, as skin elasticity is directly related to age, age should be considered whenever skin elasticity is studied. There was a correlation between environmental factors and changes in the skin’s biophysical parameters. There was a negative correlation between hydration level in the face and skin scaling. It is widely known that as the hydration level in the skin increases, there is a concomitant decrease in skin scaling. This study indirectly proved that there are changes in the hydration level or skin scaling due to environmental factors, such as relative humidity. The skin is readily irritated or stimulated by external factors. There was a correlation between sebum secretion levels in the skin and skin elasticity. An increase in the sebum secretion contributed to an augmentation in the skin softness and elasticity. There are more sebum secretions in the forehead than in the cheek. Therefore, since the sebum secretion in the cheek occurs in a miniscule amount, we can
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Nam et al.
predict no significant correlation regarding the sebum secretion in the cheek. There was no correlation between skin hydration levels with skin elasticity. In the dermis, collagen mostly contributes to skin elasticity. The hydration level of the skin relates to the hydration level of the epidermis layer. Therefore, hydration of the epidermis does not increase the elasticity of the dermis layer of the skin. However, as the hydration level in the skin decreases, there is an increase in skin scaling. Increased skin scaling contributes to
References 1. Wilhelm KP, Cua AB, Maibach HI. Skin aging. Effect on transepidermal water loss, stratum corneum hydration, skin surface pH, and casual sebum content. Arch Dermatol 1991; 127: 1806–1809. 2. Man MQ, Xin SJ, Song SP, Cho SY, Zhang XJ, Tu CX, Feingold KR, Elias PM. Variation of skin surface pH, sebum content and stratum corneum hydration with age and gender in a large Chinese population. Skin Pharmacol Physiol 2009; 22: 190–199. 3. Ezure T, Yagi E, Kunizawa N, Hirao T, Amano S. Comparison of sagging at the cheek and lower eyelid between male and female faces. Skin Res Technol 2011; 17: 510–515. 4. Marrakchi S, Maibach HI. Biophysical parameters of skin: map of human face, regional, and agerelated differences. Contact Dermatitis 2007; 57: 28–34. 5. Yun IS, Lee WJ, Rah DK, Kim YO, Park BY. Skin color analysis using a spectrophotometer in Asians. Skin Res Technol 2010; 16: 311–315. 6. Han K, Choi T, Son D. Skin color of Koreans: statistical evaluation of affecting factors. Skin Res Technol 2006; 12: 170–177.
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rigidity of the skin, thereby decreasing the skin elasticity. Such a result was found for the cheek. In conclusion, we showed that scaliness on facial skin was highly correlated with environmental factors, such as air temperature, relative humidity, and highest precipitation negatively and air pressure and duration of sunshine positively. The correlations shown between the skin biophysical parameters and environmental factors demonstrate that the skin is continuously influenced by surrounding factors.
7. Lee MR, Nam GW, Jung YC, Park SY, Han JY, Cho JC, Suh KD, Hwang JK. Comparison of the skin biophysical parameters of Southeast Asia females: forehead-cheek and ethnic groups. J Eur Acad Dermatol Venereol 2013; 27: 1521– 1526. 8. Jung YC, Kim EJ, Cho JC, Suh KD, Nam GW. Effect of skin pH for wrinkle formation on Asian: Korean, Vietnamese and Singaporean. J Eur Acad Dermatol Venereol 2013; 27: e328–e332. 9. Nouveau-Richard S, Zhu W, Li YH et al. Oily skin: specific features in Chinese women. Skin Res Technol 2007; 13: 43–48. 10. Hillebrand GG, Miyamoto K, Schnell B, Ichihashi M, Shinkura R, Akiba S. Quantitative evaluation of skin condition in an epidemiological survey of females living in northern versus southern Japan. J Dermatol Sci 2001; 27(Suppl 1): S42–S52. 11. Qiu H, Long X, Ye JC et al. Influence of season on some skin properties: winter vs. summer, as experienced by 354 Shanghaiese women of various ages. Int J Cosmet Sci 2011; 33: 377–383. 12. Roh K, Kim D, Ha S, Ro Y, Kim J, Lee H. Pigmentation in Koreans: study of the differences from
caucasians in age, gender and seasonal variations. Br J Dermatol 2001; 144: 94–99. 13. Abe T, Mayuzumi J, Kikuchi N, Arai S. Seasonal variations in skin temperature, skin pH, evaporative water loss and skin surface lipid values on human skin. Chem Pharm Bull (Tokyo) 1980; 28: 387– 392. 14. Youn SW, Na JI, Choi SY, Huh CH, Park KC. Regional and seasonal variations in facial sebum secretions: a proposal for the definition of combination skin type. Skin Res Technol 2005; 11: 189– 195. 15. Tsukahara K, Osanai O, Kitahara T, Takema Y. Seasonal and annual variation in the intensity of facial wrinkles. Skin Res Technol 2013; 19: 279–287. Address: Jae-Kwan Hwang Department of Biomaterials Scienceand Engineering & Department of Biotechnology Yonsei University, 50 Yonsei-ro Seodaemun-gu, Seoul 120-749 Korea Tel: +82 2 2123 5881 Fax: +82 2 362 7265 e-mail: [email protected]
