GIUSEPPE R CASALE¹*, ANNA MARIA SIANI¹, ALFREDO COLOSIMO²
*Corresponding author
1. Department of Physics – Sapienza Università di Roma, Piazzale Aldo Moro 2, 00185 Rome, Italy.
2. Department SAIMLAL – Sapienza Università di Roma, Piazzale Aldo Moro 2, 00185, Rome, Italy.

Abstract

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.

INTRODUCTION
The ultraviolet (UV) band of the solar spectrum is characterised by wavelengths in the range 200–400 nm but only a small fraction of the total solar flux density at the top of the atmosphere reaches the earth’s surface (1). The amount of surface levels of solar UV radiation depends on astronomic, geometric and atmospheric factors which determine daily variability, day-to-day changes and seasonal/annual variations. After the discovery of the so called Antarctic “ozone hole” in 1985, solar UV radiation has become an important environmental, ecological and atmospheric parameter to be studied and monitored (2).
The terrestrial solar UVA (320-400 nm) and UVB (280-320 nm) bands have a potential biological risk for humans. Solid experimental and epidemiological studies have shown that solar UV exposure lies behind some types of skin and eye disorders (1): the erythemal reaction is the well-known acute effect on human skin (visible as reddening mainly in fair-skinned people) due to prolonged solar UV exposure. However, absorption of small amounts of UV radiation has also beneficial effects, as the initiation of vitamin D production, ...