A new sunblock which protects the skin from UV rays also reduces heat from the sun, so you might feel like you’re enjoying a spring day – in summer.
The sunscreen uses a process called radiative cooling to lower the surface temperature of bare skin.
When tested in humid, hot outdoor conditions across two cities in China, the sunscreen prototype kept skin up to 6.0 C (10.8 F) cooler than bare skin.
And in good news for people surviving the southern hemisphere sun, it showed the best cooling performance in the seaside outdoor environments.
Radiative cooling lowers the temperature by radiating heat and reflecting it away from the surface of whatever is underneath the surface, in this case, the skin.
Most common sunscreens work by using minerals like zinc oxide and titanium dioxide as a shield, reflecting and scattering UV rays away from your skin.
Titanium dioxide is commonly used in sunscreens because it reflects heat and UV light but the particles are not the right size to produce a cooling effect.
“To maintain the comfort of the human body in the outdoor environment, sunscreens need to regulate the body’s surface temperature,” say the authors, led by Jiaqi Xu from the Beijing Key Laboratory of Green Chemical Reaction Engineering and Technology.
To create the sunblock the team adjusted the size of the titanium dioxide nanoparticles so that it could supply this cooling effect.
This new material was combined with water, ethanol, moisturizing creams and a silicone polymer to create the sunscreen.
“As far as we know, it is the first time that a radiative cooling effect has been achieved in a cosmetic, which shows promising potential in the human thermal management in the future,” the authors write.
Previous studies have found success using similar radiative cooling technologies to develop cooling fabrics and building insulation.
It costs only $0.92 for For 10 grams of the mixture, which is competitive price with other commercial sunscreens.
The sunscreen also showed high stability and water resistance as well, leading the researcher to say their prototype has promising potential on the market.
The details are published in Nano Letters.
How does sunblock work?
