Homosalate

Homosalate is a chemical sunscreen filter that provides protection in the UV-B range (280nm - 320 nm), with a peak protection at 306 nm. It is internationally approved for use in sunscreens.

Homosalate is not photo-stable, meaning it's strength as a UV filter degrades over time with exposure to the sun. Because of this, it's often used in combination with other chemical sunscreen filters as avobenzone (which protects from the UV-A range). Homosalate also helps act as a solvent for harder-to-dissolve UV filters.

(Part of the reason that sunscreens need to be frequently re-applied is due to the photo instability of many chemical sunscreen filters)

Currently, homosalate is approved in concentrations up to 10% in the EU and 15% in the US. The FDA is currently doing further research on the effects of homosalate, and it is possible that these approved concentrations will change in the future.