During the second half of the 20th century, other sources of electromagnetic fields have become the focus of health concerns, such as power lines, photovoltaic systems, microwave ovens, computer and television screens, security devices, radar equipment, and more recently, cordless telephones (DECT), cell phones, their base stations, energy-saving lamps, and Bluetooth connections. Electrified railroad lines, tram overhead lines and subway tracks are also strong sources of electrosmog. In 1996, the World Health Organization (WHO) launched the EMF (ElectroMagnetic Fields) Project to bring together current knowledge and available resources from key international and national organizations and scientific institutions on electromagnetic fields. The German Federal Office for Radiation Protection (BfS) published the following recommendation in 2006: