What does "UVA-protection has to be at least 1/3 of UVB-protection" actually mean?
EU has renewed its legislation about sunscreen claims. I read that "UVA-protection has to be at least 1/3 of UVB-protection. This will be informed with UVA-logo on sunscreen products." But what does this actually mean? I thought spf is not reversible to measure protection from UVA-radiation? What is this converted to PA/PPD? If I have spf 30, the UVA protection should be "10". Does this mean spf 10 = 90% of UVA-rays are blocked or what? I've also seen many sunscreens carrying the UVA-logo and "broad spectrum" written on them, but only active ingredient is titanium dioxide. I've been under an impression that titanium dioxide blocks only UVB and UVA2, and doesn't offer any protection from UVA1. How can this be "broad spectrum"? I am confused.