Universidad de La Salle

Energy coming from the sun that affects the Earth surface is mainly made up infrared, visible and ultra violet (UV) radiation. The solar spectrum portion belonging to UV (almost 7%) affects life on Earth. Small quantities of UV are necessary for human beings to assimilate vitamin D; in plants under normal conditions, help the photosynthesis process; but when exposition to this type of radiation is exaggerated, biological systems may be affected. UV radiation breaks biological molecules as DNA, being thus the main cause for skin cancer. Regarding eyes, a high exposition to UV radiation may cause cataracts. This article shows some properties of UV radiation, how to quantify its effect on biological tissues, especially on skin. This information might be useful when reading specialized literature about this topic and presenting public health reports about UV radiation exposition.