The UV lights from the sun is the number one cause of skin aging. Long term exposure to UV light weakens collagen and elastin in your skin, breaking down skin tissues, and causing skin laxity and wrinkles. Wearing a UVA and UVB sunscreen delays the skin’s aging process.
So what is the difference between UVA and UVB?
UVB rays strike the outer layer of your skin and changes the DNA structure. Only a small percentage of sun’s UVB rays reach the ground. However, it is the cause of sunburn and skin cancer. UVB rays are shown on the sunscreen bottle as a SPF number. Some tanning salons have UVB and UVA beds, but both can damage your skin. The SPF number refers to its ability to filter UVB rays and how long it would take to cause redness compared to not wearing a SPF sunscreen.
UVA rays cause darkening and wrinkling of your skin, also known as photoaging. Long-term exposure leads to certain types of skin cancer. UVA rays goes through window and clouds and penetrates into the deeper layer of your skin. About 95% of the UV rays reaching the ground are the UVA rays. Most tanning salons use UVA rays which are extremely harmful to your skin because this can cause skin cancer. Sunscreens with a broad spectrum protection will block UVA rays. If you want to keep your skin beautiful, it is important to wear sunscreen daily, even on cloudy days.
Source: Skin Cancer Foundation