The titanium dioxide and zinc oxide we source have a particle size of 0.2 microns, which is considered "non nano." Nanoparticles are 1,000 times smaller than the size we use. Nanoparticles may be more "invisible" on the skin, but also can penetrate your skin and pores, break down when in contact with sunlight, and cause free-radical damage to your skin. We prefer non-nano particles, since they are more stable when exposed to sunlight (making them more effective), and are less likely to be absorbed into the skin.
Every batch of our sunblock is tested by a third party lab to ensure a minimum stated SPF. Some of our products contain titanium dioxide and zinc oxide, but do not have a specific SPF stated on the packaging. Products containing 15% Titanium Dioxide and 10% Zinc Oxide will have coverage of about SPF 10-15.