Sunscreens can be divided into physical sunscreens and chemical sunscreens according to the principle of action. The word “chemical” is often feared by beauty seekers, and has even become synonymous with cheap and unsafe. To understand whether physical sunscreens are safer than chemical sunscreens, you need to clear up what physical sunscreens are and what chemical sunscreens are. 1, physical sunscreen: physical sunscreen is not the same as physical sunscreen, physical sunscreen is essentially a very fine particles made of opaque substances, can reflect or scatter ultraviolet rays, so that it can not enter the skin, broad-spectrum protection against UVA and UVB. mainly titanium dioxide, zinc oxide, talc, magnesium oxide, calcium carbonate and white clay, etc.. The advantage of physical sunscreens is that they are safe, not easily allergic, and more suitable for children and sensitive skin. The disadvantage is that it is relatively thick, coated in the face is easy to white, more unnatural. 2, chemical sunscreen: chemical sunscreen is an absorber of UV rays, mainly chemically synthesized lipids. Can absorb ultraviolet light, so that its energy attenuation off, can not reach the skin. There are many components of chemical sunscreens that can absorb UVB or UVA. commonly used components p-aminobenzoate (PABA) and its derivatives, cinnamic acid esters, salicylates, phenyl ketones, MexorylSX, Tinosorb, etc. The advantages of chemical sunscreens are light texture and good transparency, but they have some irritation. Some sunscreens have a stinging sensation in the eyes, mainly because of the irritating effect of the chemical sunscreens in them. In addition, some people may be allergic to sunscreens, mainly to the chemical sunscreen ingredient PABA, which is a very allergic chemical sunscreen, and many products choose not to add this ingredient anymore. Because both sunscreens have their advantages and disadvantages, in order to achieve better sun protection, most cosmetics contain both sunscreens in different dosage forms depending on the formulation, such as creams, lotions, sprays, wax sticks, etc. Tip: Most sunscreens nowadays are broad-spectrum, i.e. they protect against both UVA and UVB, marked with SPF and PA values. In order to make the sunscreen ingredients in it better combined with the skin, to play the best sunscreen effect, sunscreen should be used 20 minutes in advance. In addition, sunscreen must be timely replenished, if it is outdoor high-intensity sports, it is best to be able to replenish every 2 to 4 hours.