Two types of Sun Protection:
There are two types of sun protection available: chemical sunscreens and physical sunblocks. A chemical sunscreen works by absorbing, reflecting or scattering the sun’s rays (UV radiation) before they affect the skin. A physical sunblock sits on the skin's surface and reflects or scatters UV radiation before it is able to damage the skin. These two forms of protection have different methods of achieving a similar goal.
The FDA requires that all sun protection products display a Sun Protection Factor or SPF label. The SPF indicates the relative amount of sunburn protection a product can provide when used correctly. Sunscreens or sunblocks with an SPF of at least 15 are recommended, however the number can be misleading as an SPF of 30 is not twice as protective as an SPF of 15. When used properly, an SPF of 15 protects the skin from 93 percent of UVB radiation and an SPF 30 sunscreen provides 97 percent protection. Although the SPF ratings apply only to UVB rays, applying a product containing avobenzone, titanium dioxide or zinc oxide will provide broad-spectrum protection against both UVA and UVB rays.
Two types of UV Radiation:
The two types of UV radiation that can affect the skin, UVA and UVB, have both been linked to skin cancer and a weakening of the immune system. They also both cause skin color changes and contribute to premature aging. UVA rays are not absorbed by the ozone layer and penetrate deep into the skin. UVB rays mostly impact the surface of the skin and are the primary cause of sunburn. Up to 90 percent of the visible skin changes commonly attributed to aging are caused by sun exposure.