What is the function of sunscreen? Most people don't know

In summer, many girls will put on a layer of sunscreen, but many men are unwilling to put it on. This behavior is actually incorrect. Both men and women need to put on sunscreen, so what is the role of sunscreen?

The role of sunscreen

Sunlight is the main factor that causes skin aging and spots on the skin surface. Do a good job of sun protection and effectively prevent the production of melanin. You will not get tanned or hurt by the sun, and you will always stay youthful and moisturized. The working principle of sunscreen is to isolate the skin from ultraviolet rays.

Sunscreen, the sun is the main factor causing skin aging and the formation of spots on the skin surface. Do a good job of sun protection and effectively prevent the production of melanin. You will not get tanned or hurt by the sun, and you will always stay youthful and moisturized. The working principle of sunscreen is to isolate the skin from ultraviolet rays.

Sunscreen principle

Sunscreen is a skin care product that protects the skin from ultraviolet rays. Sunscreen has different protection indexes SPF (Sun Protection Factor), which refers to the time that can be extended to avoid sunburn under certain circumstances. For example, if SPF4 sunscreen is used, 2 mg of sunscreen is applied to each square centimeter of skin (about the size of a ten-dollar coin on the face), the sunburn time can be extended by 4 times. The skin that would be sunburned in one hour can be protected for up to 4 hours; it can also block 75% of UVB (calculation: (SPF-1)/SPF). The protection factor for UVA is an index for evaluating the sunscreen's ability to protect against UVA, including the Japanese PA value system and the European PPD value system.

Sunscreen works by using inorganic or organic active ingredients.

Inorganic sunscreen ingredients are usually inorganic substances such as zinc oxide and titanium oxide, which can reflect and scatter ultraviolet radiation; organic sunscreen ingredients are usually OMC (octyl methoxycinnamate) and oxybenzone, which can absorb ultraviolet radiation and convert radiation energy into heat energy. Many sunscreens protect the skin from two types of ultraviolet rays (UVA and UVB) at the same time. UVA and UVB cause different damage to the skin. From another perspective: it works through two mechanisms of reflection and absorption of light. Generally, inorganic substances reflect and organic substances absorb. The most common chemical ultraviolet absorber is PABA (para-aminobenzoic acid), which absorbs UVB. (Note: If you have sensitive skin, you should be careful when using sunscreen containing PABA, because PABA can easily cause redness and allergies in sensitive skin.) Other organic substances that absorb UV rays include:

Cinnamates, absorb UVB;

Benzophenones, absorb UVA;

Anthranilates absorb both UVA and UVB.