One of the many things I reiterate to my patients constantly is to use sunBLOCK and not sunSCREEN. The difference between the two is that screen allows a variable amount of sun through while the block does exactly that, blocks the sun’s rays.  Depending on the mode of action sunscreens can be classified into physical sunscreens (i.e., those that reflect the sunlight) or chemical sunscreens (i.e., those that absorb the UV light). The screens are separated by a number, the sun protective factor or SPF. The higher the number, the greater the protection. One old way to think about the sun’s rays was that A caused aging and B caused damage or bad effects.The SPF is an imperfect measure of skin damage because invisible damage and skin aging are also caused byultraviolet type A , which does not cause reddening or pain. Common sunscreen blocks very little UVA rays  relative to the SPF. Broad-spectrum sunscreens are designed to protect against both UVB and UVA. The best UVA protection is provided by products that contain zinc oxide or avobenzone.Titanium dioxide probably gives good protection, but does not completely cover the entire UVA spectrum. recent research suggests that zinc oxide is superior to titanium dioxide at wavelengths. I also tell my patients that when outdoors, they should reapply the sunblock every hour, especially if in the water on and off.  Below is an article about the new labeling changes mandated by the FDA to help you navigate these confusing products.

Read the article here.