As someone with a severe photosensitivity disorder, I have relied on zinc oxide as a "physical" blocker as opposed to various chemicals that often seem to be ba

As someone with a severe photosensitivity disorder, I have relied on zinc oxide as a "physical" blocker as opposed to various chemicals that often seem to be banned in the EU. But digging into the article, which is a little short on specifics, it appears that the zinc oxide is catalyzing a reaction with the "organic" compounds which also are blockers. Zinc oxide is already a pretty good UVA blocker, especially with a smaller particulate size. My guess is that this is for sunscreens with a mix of organic UVA blockers and zinc oxide, but not so much zinc oxide that you look like you are training for mime school. My preferred (aka "least objectionable") blend is only zinc oxide, so I may not have to worry. I wish I had access to a UV-VIS spectrophotometer and various defined particle sizes of zinc oxide and titanium dioxide. My suspicion is that a careful formulation -- probably arrived at via linear algebra -- of different particle sizes should allow for a sunscreen that almost has a step function at around 410 nanometers: invisible at longer wavelengths, a complete block at anything shorter than 410 nm. This way, one could avoid the ghost whiteness.