They measured eight facial skin parameters from 1092 Chinese females, collected environmental data from seven cities in China and investigated the individual lifestyles of all the volunteers.
The data revealed that there are significant regional differences in facial skin barrier characteristics and skin tone.
One of the most obvious differences was a better skin barrier in the western region, as indicated by high skin hydration and sebum secretion and a weakly acidic pH.
They also found that lighter and darker skin tones were found in the western and southern regions, respectively.
Elaborating on the findings, reserachers explained that they divided skin indicators into “skin barrier function” and “skin tone”.
“With regard to skin barrier function, the regions showed a western-others-southern trend. Women living in two western cities (Chengdu, Xi’an) had a better skin barrier, as indicated by high hydration and sebum secretion, together with a weakly acidic pH value.
“Those women who live in South China (Guangzhou) had a poor skin barrier, as indicated by highest transcutaneous water loss, lowest sebum secretion and a neutral pH value. Other regions did not reveal significant barrier characteristics,” they wrote in the journal Nature.
They pointed out that compared to the western regions (Chengdu, Xi’an), Guangzhou has the worst circumstance of air pollution and longer sunshine duration – two key factors to explain such difference.
“From the perspective of pollution in Guangzhou, the particulate matter and nitrogen dioxide had the largest effects. Our results complement the association between pollution conditions and the skin barrier in Guangzhou,” they added.
They also found that differences in the skin tone level was consistent with the skin barrier conclusions.
They wrote that in Guangzhou, the darker skin tone was easy to observe. Lighter skin tones were observed in relatively well-protected regions of Chengdu and Xi’an.
From the perspective of pigment distribution, women in the western regions received lower sunshine duration and ultraviolet rays with lower melanin content, while the melanin content in Guangzhou was the highest due to longer sunshine duration.
In terms of lifestyle factors, cosmetic use had the greatest impact on skin pH and hydration content, followed by past medical history.
“The positive impact of beauty habits on the skin has been proven in Korea and in the Chinese female population in China. Lee et al. found that using sunscreen every day, wearing base makeup daily, and using moisturizers improved hydration, transcutaneous water loss, and elasticity significantly after adjusting for age and region,” they noted.
The researchers concluded that they hoped the data could act as a guide for regional skincare routines and advice.
"A cross-sectional study of Chinese women facial skin status with environmental factors and individual lifestyles"
Authors: Fan Yi, et al