UVB has a short wavelength and UVA has a long wavelength. Therefore, UVB energy is large, and it mainly destroys the epidermis, but UVB consumes almost the same amount of UVB through the epidermis, and not much can reach the dermis. And UVA not only destroys the epidermis, but also easily reaches the dermis to continue to destroy.

The skin is the organ with the largest surface area of the human body, and it bears various external pressures daily, such as environmental pollution, UV damage, oxidative stress,etc.As the metabolism rate decreases, all kinds of "cell garbage" accumulate unknowingly.At this time, autophagy comes in