The sun emits both UVA and UVB rays. UVA rays contribute to premature aging, collagen and elastin degradation and increase the chance of skin cancers. UVB rays cause your skin to get a sun burn. Naturally, when picking out a “good” sunblock, you would think to pick a higher SPF number to get better protection.
SPF only blocks UVB (burning rays) so although your skin is not burning, you are still at an increased risk for developing skin cancers and photodamage. An ideal sunblock is one with the active ingredients of zinc oxide and titanium oxide with an SPF of at least 30. These are called physical blocks. These two active ingredients protect against both types of damaging rays.
Listed below is a chart on the most common ingredients in sunblocks and how they protect your skin.
UVA are deeper penetrating rays and hence cause more damage to the collagen causing earlier wrinkling. Titaniuma nd Zinc provide the best protection for the loger UVA rays that are not blocked by other sunscreens.