A UV Index sundial on compact disk

This paper provides information on the capability of a compact disk (CD) of estimating the UVI (Ultra Violet Index). This parameter is an indicator of the erythemally weighted UV radiation at surface. It is defined as the integration of solar irradiance (280–400 nm) measured on a horizontal plane, weighted by the erythemal (skin reddening) action spectrum, and properly scaled to become a dimensionless number. The UVI is widely used as an indicator of UV levels at the earth’s surface providing public awareness of the effects of prolonged exposure to the sun’s rays. Our CD based device is designed for personal use and may become a valuable tool for a better communication of the UVI to the public with the hope to draw people’s attention to use it and to adopt adequate sun protection behaviours.