On 22 April , it is world Earth Day . The idea is to raise awareness of the need to rely on renewable energy. The EU requires its member states to provide a a 27% share of renewable energies by 2030—up from a 23.

Silver has been used as biocide for medical purposes since the 1930s. Today nanometric size silver particles are used to prevent unpleasant odour caused by bacteria in sport shirts or socks .