New sunscreen: scientists have achieved six degrees cooler skin

Scientists from China have found a way to change this: they have improved the formula of the cream so that it not only blocks UV radiation, but also cools the skin.

The basis of the new development was an already known component - titanium dioxide (TiO₂). It is usually added to mineral sun creams to reflect ultraviolet light. But as the researchers found out, the standard particle size of TiO₂ does not provide a cooling effect. Then chemists led by Rufan Zhang decided to experiment with nanoparticle sizes and created a prototype cream that reflects not only UV light but also a significant amount of heat.

The new formula includes six main ingredients: titanium dioxide itself in several fractions (1-3 microns, 200-300 nm and 10-20 nm), water, ethanol, moisturiser, pigments and cosmetic silicone (polydimethylsiloxane). According to the scientists, thanks to a special configuration and radiation cooling, this cream is able to dissipate heat while it protects the skin from the sun.

In tests, it was able to achieve a protection factor of SPF 50 and provide water resistance. The effectiveness of the formulation was tested using a xenon lamp that simulates sunlight: even after 12 hours of application, the new cream retained its properties. Experiments on both animals and volunteers confirmed that the product does not irritate the skin and does not cause allergic reactions.

However, the main achievement of the authors of the study is that the new cream cooled the skin by more than six degrees Celsius compared to the uncovered area, as well as almost three degrees compared to conventional sunscreens. It was possible to achieve this effect through so-called "radiative cooling", in which the coating actively reflects or radiates excess heat.

The results of the work published in the journal Nano Letters (2024). There scientists note that such an approach has already been used in the creation of "breathable" fabrics and coatings for walls, and now breaks through and in the industry of sunscreens.