skin quality and aesthetics, especially for the face and hands, are reflected as a youthful appearance and determined by the following key factors: aging, firmness & elasticity, moisture retention, sun protection, skin rejuvenation, sensitivity response, anti-oxidation, and
pigmentation. all of these factors are greatly affected by the exposure of one’s skin to the environment and are epigenetically controlled/regulated. environment stimuli such as pollution, chemicals, and smoking will cause an epigenetic change (i.e., dna methylation) in genes related to one or more factors mentioned above in skin cells, which leads to gene inactivation at different degrees.