There is growing interest in nanotechnology with a number of reports highlighting that there are some gaps in the knowledge of the risks posed by nanoparticles to human health and the environment. There is no official definition of the term “nanoparticle”, but generally this term is taken to mean particles with one or more dimensions [...]

Most sunscreens with an SPF of 15 or higher do an excellent job of protecting against UVB. SPF — or Sun Protection Factor — is a measure of a sunscreen’s ability to prevent UVB from damaging the skin. Here’s how it works: If it takes 20 minutes for your unprotected skin to start turning red, using an SPF 15 sunscreen theoretically prevents reddening 15 times longer — about five hours.

Your body makes vitamin D when you are exposed to the ultraviolet B (UVB) rays in sunlight. You probably need from 5 to 30 minutes of exposure to the skin on your face, arms, back or legs twice every week. Since exposure to sunlight is a risk for skin cancer, you should use sunscreen after [...]