Dose-dependent progressive sunscreens. A new strategy for photoprotection?

A new generation of UV filters has been developed that act by limiting the dose of radiation rather than by blocking a fraction of the solar irradiance on the skin surface. Such progressive sunscreens are based on the photochemical transformation of suitable precursors upon exposure to sunlight. Broadband sunscreens are thus generated "on demand", affording protection when, where, and to the extent that it is needed, providing higher protection to more exposed areas, and increasing the UV blocking capacity as the radiation dose increases. Encapsulation in silica particles isolates the precursors and transformation products, further improving the efficacy, safety, and environmental impact of the use of sunscreens.