Coefficients for Assessing the Visibility of Materials Used in Anti-Smog Face Masks

The application of phosphorescence for the modification of face mask materials is motivated by the need to appreciably increase their visibility while using graphical elements with a relatively small area. Phosphorescent dyes absorb part of the visible spectrum while emitting radiation at wavelengths that are longer than the absorbed ones. Thus, a phosphorescent substance can emit light even if it is not being illuminated at a given time (but was before). This paper describes studies of the optical properties based on parameters such as the reflectance coefficient, chromaticity coordinates, as well as luminance measured from digital images for two models of smog-protective face half-masks differing in terms of their inner layer with filtration properties and outer printed layer. The external surface of one mask type is printed with a phosphorescent solid star pattern, while the other with a phosphorescent open star pattern. The influence of the inner filter layer was assessed in correlation with the colour of the outer layer and the type of printing. Moreover, the phenomenon of phosphorescence was identified. The study resulted in developing a material with properties providing better visibility under defined use conditions.