Most Sunscreens are affected by UV
Even though zinc is the best active ingredient to reduce UV absorption into the skin, when exposed sunlight, organic materials, like zinc, decompose on the skins surface and release free radicals that work to kill cell membranes.
The science behind 3rd Rock SunBlock's zinc shines! The zin used in 3rd Rock SunBlock is inorganic since we chelate it, in other words attach, with another molecule, l-Argenine. With this chelation, there is NO breakdown in the presence of UV light and it therefore absorbs UVA better than any other brand. Period.