The Use of Hemispheric Directional Reflectance Method to Verify the Usefulness of Filters Protecting the Skin Against...

Infrared radiation (IR) has a wide spectrum of both positive and harmful effects on the human body. Negative properties, manifested by increasing the level of reactive oxygen species (ROS), affect the skin ageing acceleration. Other adverse effect of infrared exposure is related to its ability to significantly penetrate deep into the skin, between its layers, up to blood vessels and other tissues and warm them up. Due to its harmful effects, protecting the skin against infrared radiation becomes an important issue.

The aim of the research was verifying the usefulness of filters available on the market with protection against infrared radiation declared by the manufacturers, by examining their impact on the directional reflectance of the human skin.

A group of 27 people was gathered, to obtain the results. Four products were applied on the participant's forearm skin, and then measurements of the directional reflectance of the skin were made at successive time points, using the 410-Solar reflectometer. The collected data was analyzed, and showed changes in reflectance under the influence of the applied protective products.

The products used in the study showed a statistically significant effect on the directional reflectance of the human skin in near infrared radiation range and little effectiveness for higher wavelengths.

The results indicate that the selected products show radiation protection against IR radiation only after several dozen minutes of application, which may suggest that they must penetrate deeper skin layers to be effective. Hemispheric directional reflectance turned out to be an effective method allows to assess the effectiveness of protective properties of cosmetics.