Chemical and mineral sunscreens are surprisingly similar

Metal oxide sunscreens protect skin by absorption, not by reflection or scattering

Sunscreens generally fall into one of two categories, mineral or chemical, depending on their key ingredients that provide protection from the sun’s harmful UV rays. These ingredients are called filters and they provide sun protection. For a long time, it was believed that mineral filters, such as titanium oxide and zinc oxide, provided sun protection by reflecting or scattering most of these harmful rays away from the skin. This is actually not the case but it is a common misconception. Properly understanding how ingredients work is important because it helps us to improve how we create and choose products to suit our needs.

To understand how metal oxides protect us from harmful sun rays, the scientists who performed this study used special instruments and calculations to measure whether and how much light was reflected, absorbed or passed through their test materials. This helped them test the ways in which the mineral filters, titanium oxide and zinc oxide, protect us from the sun. By testing these two types of metal oxides, the scientists showed that they only reflect a small amount of UV rays, around 4-5%, which is not enough for strong sun protection. Their testing showed that the majority of sun protection provided by these metal oxide mineral filters is through their absorption of UV rays.

This study gives us strong scientific evidence that the traditional view of light reflection or scattering is not the main way in which mineral filters protect us from the sun’s harmful rays. Describing these sunscreens correctly as absorbers shows that they work in the same way as chemical sunscreens, both protecting the skin by absorbing UV rays. Recognizing absorption as their main function also helps explain the terms used for different types of sunscreens and gives a clearer, more accurate idea of how they work. Ultimately, this knowledge helps us make better-informed decisions about how to protect our skin from the sun.

For further information read the full paper.