Your Sunscreen may not protect against all UV light
In a study of 29 top selling sunscreen only 6 have the right amount of active ingredients to protect against UV-A light. While UV- A and UV-B are both harmful, UV-A penetrates much deeper into your skin and the damage lasts throughout the year. UV-B rays are blocked by windows whereas UV-A rays penetrate through glass. Therefore, protection from UV- A radiation may be even more important than protection from UV-B.
When choosing sunscreen to provide adquate UV-A protection, look for ingredients with either zinc or titanium oxide or a combination of avobenzone and octocrylene. Sunscreen should be applied liberally to provide maximum sun protection coverage.