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Received: 4 May 2023 Accepted: 6 June 2023
DOI: 10.1111/srt.13397
ORIGINAL ARTICLE
Effects of winter indoor environment on the skin: Unveiling
skin condition changes in Korea
Eun Hye Park Da Jung Jo Hyo Won Jeon Seong Jin Na
Research institute, Celltem Pharm Co., Ltd.,
Seoul, South Korea
Correspondence
Eun Hye Park, Research institute, Celltem
Pharm Co., Ltd., 298, Beotkkot-ro,
Geumcheon-gu, Seoul 08510, Korea.
Email: dms2353@gmail.com
ABSTRACT
Background: In Korea, winter can cause skin dryness due to low relative humidity (RH);
moreover, indoor heating devices promote moisture loss and air pollution. If dryness
persists, dead skin cells accumulate, leading to skin problems; therefore, careful skin
care is required. This study aimed to compare changes in skin conditions when exposed
to an indoor environment for a short period of 6 h in winter, and to suggest proper
winter skin care practices.
Methods: A randomized, split-face clinical study was conducted in which healthy
female participants with normal skin were exposed to an indoor environment with a
heater turned on for a short period at least 6 h per day in the winter season, and cream
was applied to one side of the face. Skin temperature, hydration, sebum, transepider-
mal water loss (TEWL), elasticity, texture, pores, redness, and wrinkles were measured
at the treated and nontreated sites.
Results: After 6 h of exposure, skin temperature, pores, roughness, redness, and
wrinkles significantly increased (p<0.05) on the face, whereas TEWL significantly
increased on the forearm (p<0.05). However, sebum secretion appeared to func-
tion as a barrier to maintain homeostasis in the facial skin. Elasticity, pores, texture,
and wrinkles in the cream-treated ceramide site improved compared to those in the
nontreated site (p<0.05). The moisture content was also significantly higher in the
forearm (p<0.05).
Conclusion: Changes in skin parameters of participants with healthy skin were
observed even after short-term exposure to an indoor environment in winter. Creams
containing ceramide maintain skin homeostasis and protect the skin barrier; therefore,
it is recommended to use such creams to prevent skin damage and maintain healthy
skin, particularly during prolonged exposure to indoor environments during winter.
KEYWORDS
ceramide NP, indoor environment, normal skin, skin barrier, skin characteristics, winter season
This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided
the original work is properly cited.
© 2023 The Authors. Skin Research and Technologypublished by John Wiley & Sons Ltd.
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https://doi.org/10.1111/srt.13397
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1INTRODUCTION
As per the Korean Statistical Information Service, the country has
the longest working hours among OECD countries, with a total of
1928 h as of 2021. Many office workers in Korea complain about
feeling dry air during winter. Hot air blown out by heating devices
used in offices can strip the skin of moisture; moreover, providing
proper ventilation may be difficult in cold weather. This can result in
exposure to indoor dust and dry environments. If this environmental
exposure persists, it can lead to skin stress and may accelerate the
aging process.1Several studies have reported that prolonged expo-
sure to extremely low humidity can lead to skin conditions, such as
contact dermatitis in workers.2,3 A previous study demonstrated that
abrupt fluctuations in humidity can have an adverse effect on skin bar-
rier function, potentially leading to skin diseases.4According to Jang
et al.,5women over 30 years of age experienced a greater reduction
in skin elasticity as a result of repeated alterations in temperature and
humidity.
Changes in temperature also affect the skin. Many studies have
reported the relationship between temperature changes and skin
hydration as well as TEWL. Temperature and TEWL showed a positive
correlation.6,7 However, the relationship between relative humidity
and TEWL has not been clarified in previous papers.8,9 Numerous stud-
ies have examined seasonal changes in skin characteristics. A previous
study found that the incidence of atopic skin exacerbation, a condition
characterized by dry, itchy, and inflamed skin, is highest in winter and
spring. Specifically,the incidence rates of atopic skin exacerbation were
25%, 19%, 11%, and 36% in the spring, summer, autumn, and winter
seasons, respectively.10 According to Qiu et al.,11 there was no notable
difference in aging parameters between summer and winter in relation
to age. However, changes were observed in certain functional crite-
ria, such as skin color, pigmentation, sebum secretion, and hydration. In
another study, men showed significant changes in wrinkle depth during
winter season.12
People commonly experience skin problems and discomfort during
winter, especially when exposedto dry indoor environments. However,
only few studies in Korea have investigated the effects of winter con-
ditions in an office environment on normal skin without skin diseases.
Therefore, in this study, changes in skin characteristics were investi-
gated by controlling the exposure environment for 6 h. In addition,
improvements in the area where a ceramide-containing cream was
applied were investigated.
2METHODS
2.1 Participants and environmental condition
We recruited and selected Korean women between the ages of 20 and
59 years with normal skin type. A normal skin type was judged based on
a sebumeter’s measured value of 30−60.13 This study was conducted
in accordance with the ethical standards of the Declaration of Helsinki
and approved by the appropriate Institutional Review Board (P01-
TAB LE 1 Number of participants (N), age, and sebum content at
baseline point.
Measurement
site NAge (mean ±SD) Sebum (mean ±SD)
Face 20 41.90 ±9.62 43.18 ±12.84
Forearm 12 34.83 ±8.85 –
202301-01-037). The purpose and method of the study and possible
adverse reactions were explained to all participants who voluntarily
partook in this study and filled out an informed consent form. The
number and age of the participants in each region are summarized in
Ta b l e 1.
To achieve exposure to a dry indoor environment in winter, the
study was conducted in January and February, when humidity was
low, according to the Korea Meteorological Administration website
(https://www.weather.go.kr/). During the study period, the minimum
and maximum mean temperatures in Seoul were −5.68◦C and 2.79◦C,
respectively, and humidity was 23.05% (Figure 1). The participants
washed their faces and forearms with the cleansing foam in a labo-
ratory equipped with constant temperature and humidity conditions
(room temperature 20◦C–24◦C, humidity 45∼55% RH) and waited for
30 min for skin stabilization.
We evaluated the skin temperature, hydration, sebum, TEWL, elas-
ticity, pores, texture, wrinkles, and redness on the participants’ faces
and forearms before exposure (baseline) and 1 and 6 h after exposure.
The participants waited for 6 h in an area maintained at a temperature
of 25 ±1◦C and a humidity of less than 20% that was achieved by using
a heater until the study was concluded.
2.2 Treatment
Facial creams were selected to investigate their effectiveness in man-
aging potential skin changes caused by indoor conditions during winter.
The key ingredients of the creams include ceramide NP, ectoin, glyc-
erin, trehalose, and 2,3-butanediol to improve the skin barrier and
moisturize it.
After the baseline measurement, approximately 0.3 g of cream was
applied to one side of the face (randomized among the participants).
For the forearm, 12 µL of cream was applied to the treated site in a
2×2 cm area (randomization) and the sleeve was rolled up to allow the
area to be exposed to the environment.
2.3 Measurement of skin biophysical parameters
Skin parameters, such as temperature, hydration, sebum, TEWL, elas-
ticity, pores, texture, wrinkles, and redness were measured using
various devices in a noninvasive method.
The skin temperature in the forehead area was recorded using a
noncontact IR thermometer (HuBDIC Co., Ltd., South Korea). Skin
hydration, sebum, TEWL, and skin elasticity were measured on the
PAR K ET AL.3of8
FIGURE 1 Average daily temperature (T) and relative humidity (RH) during the study period.
cheek using Corneometer®CM 825, Sebumeter®SM815, Tewame-
ter TM HEX, and Cutometer MPA580 devices (C+K, Köln, Germany),
respectively. Skin hydration and TEWL were additionally measured on
the forearm because the external influence was minimized and areas
with less sweat or hair could produce accurate and reliable results.
Cheek skin redness, pores, texture, and wrinkles were measured using
an Antera 3D CS (Miravex, Ireland).
2.4 Statistical analysis
All results are expressed as mean ±standard deviation (SD), and
data were calculated using SPSS Statistics version 28.0 (IBM Corp.,
USA). Normality was assessed using the Shapiro–Wilk test for all data.
Data for comparing the baseline and postexposure time points were
analyzed using paired ttests (parametric) and Wilcoxon signed-rank
tests (nonparametric). Changes in skin characteristics between the
treated and nontreated sites were compared using RMANOVA. The
relationship between skin parameters was analyzed using Pearson’s
correlation coefficient test. Differences were considered statistically
significant at p<0.05.
3RESULTS
According to the indoor environment exposure time in winter (temper-
ature, 25 ±1◦C; humidity <20%), the results of skin parameters (tem-
perature, moisture, sebum, TEWL, elasticity, wrinkles, pores, texture,
and redness) are shown in Figure 2.
The skin temperature of the nontreated site gradually increased by
0.54% and 0.73% after exposure for 1 h (p<0.01) and 6 h (p<0.001),
respectively. The skin temperature of the treated site significantly
increased by 0.62% within 1 h and was maintained at 0.55% for up to
6h(p<0.01, Figures 2A and 4A).
Regarding hydration and TEWL, compared to the baseline, there
was no significant difference between the treated and nontreated sites
after 6 h of exposure (Figures 2B and Cand 4B and C). However,
when hydration and TEWL were measured equally on the forearm,
the results were completely different from those measured on the
cheek. Hydration of the nontreated site on the forearm did not change
significantly until after 6 h of exposure. The rate of change at the non-
treated site was 1.11%. That of the treated site significantly increased
by 81.81% and 73.02% after 1 and 6 h of exposure, respectively
(p<0.001). After exposure for 1 and 6 h, the increase in hydration at
the treated site was significantly higher than that at nontreated sites
(p<0.001, Figures 3A and 4D). The TEWL of the nontreated site in
the forearm significantly increased by 22.40% and 26.70% from 1 h
(p<0.05) to 6 h of exposure (p<0.01), respectively. That of the treated
site decreased slightly by 2.74% and 0.06% from 1 to 6 h of exposure,
respectively. After exposure for 1 and 6 h, the decrease in TEWL at the
treated site was significantly higher than that at the nontreated site
(p<0.01, Figures 3B and 4E).
Sebum at both sites significantly increased after 1 and 6 h of expo-
sure (p<0.001). After 1 h of exposure, sebum content at the treated
site was significantly higher than that at the nontreated site (p<0.001,
Figures 2D and 4F).
The skin elasticity of the treated site significantly increased by
2.61% when exposed for 1 h (p<0.01), whereas that of the non-
treated site did not change significantly until after 6 h of exposure.
After exposure for 1 and 6 h, the increase in elasticity at the treated
site was significantly higher than that at the nontreated site (p<0.05,
Figures 2E and 4G).
The skin pore of the nontreated site significantly increased by
29.45% and 36.12% when exposed for 1 and 6 h, respectively (p<0.01),
and those of the treated site did not significantly change until after
6 h of exposure. After 1 and 6 h of exposure, the number of pores in
the treated site was significantly lower than that in the nontreated site
(p<0.01, Figures 2F and 4H).
The skin roughness of the nontreated site significantly increased by
7.06% and 7.38% when exposed for 1 and 6 h, respectively (p<0.01),
and that of the treated site did not significantly change until after 6 h
of exposure. After 1 h (p<0.001) and 6 h (p<0.01) of exposure, the
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FIGURE 2 Comparison of skin parameters of the treated and nontreated site on the face before and after 1 and 6 h of exposure to an indoor
environment in winter. (A) skin temperature, (B) hydration, (C) TEWL, (D) sebum, (E) elasticity, (F) pore, (G) roughness, (H) redness, and (I) wrinkles
were evaluated. *p<0.05, **p<0.01, ***p<0.001 baseline vs. 1 and 6 h postexposure time points. †p<0.05, ††p<0.01, †††p<0.001. nontreated
vs. treated site.
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FIGURE 3 Comparison of skin parameters of the treated and nontreated site on the forearm before and after 1 and 6 h of exposure to the
indoor environment in winter: (A) hydration and (B) TEWL. *p<0.05, **p<0.01, ***p<0.001 baseline vs. 1 and 6 h postexposure time points.
†p<0.05, ††p<0.01, ††† p<0.001, nontreated vs. treated site.
TAB LE 2 Correlation of skin parameters after 6 h of exposure to an indoor environment in winter.
Treated site Nontreated site
Temperature Hydration TEWL Sebum Temperature Hydration TEWL Sebum
Temperature 1.000 0.054 0.453*−0.198 1.000 −0.238 0.354 −0.142
Hydration 0.054 1.000 0.060 −0.316 −0.238 1.000 0.123 0.110
TEWL 0.453*0.060 1.000 −0.123 0.354 0.123 1.000 −0.175
Sebum −0.198 −0.316 −0.123 1.000 −0.142 0.110 −0.175 1.000
Elasticity 0.000 0.687** -0.324 −0.113 −0.229 0.349 0.087 −0.228
Pore 0.375 −0.346 0.477*0.202 0.365 0.074 0.508*−0.187
Roughness 0.184 −0.362 0.239 0.369 0.388 0.078 0.513*−0.224
Redness 0.174 0.124 −0.284 0.270 0.161 0.163 −0.284 0.275
Wrinkle 0.455*0.062 0.316 0.153 −0.265 0.355 −0.088 0.409
*The correlation is significant at the 0.05 level (2-tailed).
**Correlation is significant at the 0.01 level (2-tailed).
increase in roughness at the treated site was significantly lower than
that at the nontreated site (Figures 2G and 4I).
Skin redness at both sites increased significantly after 1 h (p<0.001)
and 6 h (p<0.05) of exposure. However, there were no differences
between the two sites until after 6 h of exposure (Figures 2H and 4J).
Skin wrinkles at nontreated sites significantly increased by 3.67%
and 5.84% when exposed for 1 h (p<0.01) and 6 h (p<0.05), respec-
tively; however, those at the treated site did not significantly change
until after 6 h of exposure. Furthermore, after 6 h of exposure, the
increase in wrinkles at the treated site was significantly lower than that
at the nontreated site (p<0.05, Figures 2I and 4K).
Ta b l e 2shows the relationships between skin parameters that can
affect the skin barrier after 6 h of exposure to indoor environments in
winter between the treated and nontreated sites. A significant positive
correlation between hydration and elasticity was found at the treated
site where the ceramide cream was applied (p<0.01). A significant pos-
itive correlation was found between TEWL, pore size, and roughness at
the nontreated sites (p<0.05). In contrast, the treated sites showed a
positive correlation only between TEWL and pore (p<0.05).
4DISCUSSION
In Korea, which has four distinct seasons, many people complain of dry
skin due to office heaters every winter. Therefore, we aimed to inves-
tigate the effect of indoor environmental exposure on the skin using a
noninvasive method and to determine whether these changes could be
improved by applying a ceramide-containing cream.
The skin temperature appeared to be affected by an increase in
the ambient temperature owing to the use of heaters. The body
maintains a constant skin temperature to regulate its internal envi-
ronment, which is essential for homeostasis. Skin temperature also
exhibits a high correlation with the temperature of the surround-
ing environment.9In this study, although there was no difference
between the two sites, the treated site maintained a relatively low skin
temperature.
Skin redness also appears to be affected by changes in skin tempera-
ture. Several studies haveshown that skin temperature and redness are
positively correlated, as capillaries and blood flow change with ambient
temperature.14
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FIGURE 4 Rate of change of skin parameters after 1 and 6 h of exposure compared to baseline in treated and nontreated areas; (A)
temperature, (B) hydration on the cheek, (C) TEWL on the cheek (D) hydration on the forearm, (e) TEWL on the forearm, (F) sebum, (G)
elasticity, (H) pore, (I) roughness, (J) redness, (K) wrinkle were evaluated. †p<0.05, ††p<0.01, †††p<0.001. nontreated vs. treated site.
PAR K ET AL.7of8
Hydration and TEWL in the face did not change significantly with
exposure time. This suggests that the participant had a normal healthy
skin barrier and adequate sebum secretion, which helped to main-
tain normal levels of skin hydration and TEWL on the face. However,
hydration and TEWL in the forearm showed the opposite results. After
6 h of exposure, hydration decreased rapidly and TEWL significantly
increased. This is because this area is less affected by the secretion of
sebum and sweat.15 Furthermore, hydration and TEWL at the treated
site in the forearm were significantly improved.
In many studies, the skin barrier has been improved by the applica-
tion of products that contain ceramide to dry skin; however, there are
few studies that show its effect on healthy normal skin.16
One hour after cream application, the sebum content of the skin
increased significantly because of the lipid components present in the
cream. However, there was no significant difference in sebum con-
tent between the cream-treated and nontreated sites after 6 h. This
is because even the nontreated site can protect the skin barrier during
daytime by secreting sebum with a content similar to that of the treated
site. According to Boer et al.,17 the most important biophysical param-
eters that determine the condition of the skin barrier are the skin pH,
epidermal hydration, TEWL, and sebum secretion.
An increase in skin temperature can cause the pores to expand and
expose the skin to dry air, especially in an enclosed environment, mak-
ing the skin rough and prone to wrinkles. This can lead to skin fatigue
and eventually decreased skin elasticity.5,18
Hydration and elasticity were positively correlated at the treated
site, while TEWL was positively correlated with pores and roughness at
the nontreated site. The healthy skin of the participants maintained its
barrier function through appropriate sebum secretion; however, this
could still affect various aging-related parameters. Creams containing
ceramide were found to improve the elasticity, porosity,roughness, and
wrinkling of the skin.
Therefore, in this study, continuous exposure to indoor environ-
ments in Korea during winter was observed to cause aging. It is
suggested that this problem can be prevented by applying a ceramide
cream, which improves the skin barrier.
5CONCLUSIONS
In this study, we investigated the impact of normal facial skin when
exposed to a high-temperature, low-humidity indoor environment for a
short period during winter. Our findings revealedthat after 6 h of expo-
sure, skin temperature, roughness, redness, and wrinkles increased
on the facial skin, whereas hydration and TEWL remained unchanged.
In addition, the forearm area showed a significant decrease in hydra-
tion and an increase in TEWL. However, using creams containing 5%
ceramide significantly increased hydration and decreased TEWL in the
forearm area. Moreover, cream application improved the facial skin
elasticity, pore size, roughness, and wrinkles. These results indicate
that even individuals with normal skin experience adverseeffects when
exposed to indoor winter environments for a brief period. The use of
a cream containing ceramide could be an effective solution to address
these issues.
CONFLICT OF INTEREST STATEMENT
The authors declare no conflict of interest.
DATA AVAILABILITY STATEMENT
The data supporting the findings of this study are available from the
corresponding author upon reasonable request.
ORCID
Eun Hye Park https://orcid.org/0000-0003-1566-4515
REFERENCES
1. Tsukahara K, Hotta M, Fujimura T, Haketa K, Kitahara T. Effect of
room humidity on the formation of fine wrinkles in the facial skin of
Japanese. Skin Res Technol. 2007;13:184-188.
2. Chou TC, Lin KH, Sheu HM, et al. Alterations in health examination
items and skin symptoms from exposure to ultra-low humidity. Int Arch
Occup Environ Health. 2007;80:290-297.
3. Sato M, Fukayo S, Yano E. Adverse environmental health effects of
ultra-low relative humidity indoor air. J Occup Health. 2003;45:133-
136.
4. 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;119:900-904.
5. Jang SI, Lee M, Jung Y, et al. Skin characteristics following repeated
exposure to simulated outdoor and indoor summer temperatures in
South Korea and Southeast Asia. Int J Cosmet Sci. 2021;43:352-358.
6. Mathias CGT, Wilson DM, Maibach HI. Transepidermal water loss as a
function of skin surface temperature. J Invest Dermatol. 1981;77:219-
220.
7. Grice K, Sattar H, Sharratt M, Baker H. Skin temperature and transepi-
dermal water loss. J Invest Dermatol. 1971;57:108-110.
8. Roure R, Lanctin M, Nollent V, Bertin C. Methods to assess the pro-
tective efficacy of emollients against climatic and chemical aggressors.
Dermatol Res Pract. 2012;2012:1.
9. CravelloB, Ferri A. Relationships between skin properties and environ-
mental parameters. Skin Res Technol. 2008;14:180-186.
10. Uenishi T, Sugiura H, Uehara M. Changes in the seasonal dependence
of atopic dermatitis in japan. JDermatol. 2001;28:244-247.
11. Qiu H, Long X, Ye JC, et al. Influence of season on some skin proper-
ties: winter vs. summer, as experienced by 354 Shanghaiese women of
various ages. Int J Cosmet Sci. 2011;33:377-383.
12. 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.
13. Youn SW, Kim SJ, Hwang IA, Park KC. Evaluation of facial skin type by
sebum secretion: discrepancies between subjective descriptions and
sebum secretion. Skin Res Technol. 2002;8:168-172.
14. Jang SI, Choi J, Han J, Kim EJ, Lee HK. Differences between cheeks
and dorsal hands skin properties during skiing in a cold and windy
environment. J Cosmet Dermatol Sci Appl. 2017;07:27-33.
15. Pinnagoda J, Tupker RA, Agner T, Serup J. Guidelines for transepi-
dermal water loss (TEWL) measurement. A report from the standard-
ization group of the European Society of Contact Dermatitis. Contact
Dermatitis. 1990;22:164-178.
16. Kono T, Miyachi Y, Kawashima M. Clinical significance of the
water retention and barrier function-improving capabilities of
ceramide-containing formulations: A qualitative review. JDermatol.
2021;48:1807-1816.
8of8 PA RK ET AL.
17. Boer M, Duchnik E, Maleszka R, Marchlewicz M. Structural and bio-
physical characteristics of human skin in maintaining proper epidermal
barrier function. Postepy Dermatol Alergol. 2016;33:1-5.
18. Denda M, Sokabe T, Fukumi-Tominaga T, Tominaga M. Effects of skin
surface temperature on epidermal permeability barrier homeostasis. J
Invest Dermatol. 2007;127:654-659.
How to cite this article: Park EH, Jo DJ, Jeon HW, Na SJ.
Effects of winter indoor environment on the skin: Unveiling
skin condition changes in Korea. Skin Res Technol.
2023;29:e13397. https://doi.org/10.1111/srt.13397
