The role of sun protection

In the summer, you must pay attention to sun protection, because the summer sun will be very hot and the ultraviolet rays are very strong. If you don't do a good job of sun protection, it is very easy to leave some sun spots on the skin. When doing sun protection, most people will choose to apply some sunscreen or use some sunscreen spray to block ultraviolet rays. So what are the functions of sun protection?

Sunscreen, which can be a spray, lotion, gel or wax, is usually made up of a mix of chemicals. While the inorganic chemicals in sunscreen reflect or scatter light away from the skin, the organic (carbon-based) ones absorb UV rays so our skin doesn't.

How it works

Some inorganic chemicals, including minerals like zinc oxide or titanium dioxide, act as physical sunscreens. They reflect UV light similar to the way white paint reflects light. The white noses on beaches in the 1980s and 1990s were due to these compounds; because manufacturers now make the inorganic particles smaller, we don't see the visible white.

Along with inorganic chemicals, sunscreens often contain organic chemicals with names like avobenzone or oxybenzone. Rather than physically deflecting UV rays, these molecules absorb UV radiation through chemical bonds. As the adhesive absorbs UV radiation, the sunscreen ingredients slowly break down and release heat.

The drop in SPF

The SPF on a sunscreen bottle stands for Sun Protection Factor, and refers to how well the sunscreen protects against a type of ultraviolet radiation, called UVB (it's also known as UVB, which is useful for burning). UVB rays cause sunburn and several types of skin cancer.

Another type of radiation, called UVA radiation, penetrates deeper into the skin, causing premature wrinkles, age spots, and also increasing the risk of certain skin cancers. Sunscreen lotions are labeled as providing broad-spectrum blocking against both UVA and UVB, but there is currently no standard that lists UVA blocking ability. Inorganic sunlight-deflecting chemicals deflect both UVA and UVB rays.

Most organizations use sunscreens with an SPF between 15 and 50 (SPF ratings higher than 50 have not been shown to be more effective than SPF 50). According to the Mayo Clinic, a sunscreen with an SPF of 15 protects against about 93 percent of UV rays, while one with an SPF of 30 protects against 97 percent of their rays. No SPF can block 100% of UV rays.