Electromagnetic fields (EMFs) are inevitably produced by any electrical apparatus. Examples include power lines and cables, electrical appliances, mobile phones and base stations, and TV and radio transmitters. For more than thirty years there have been concerns about health risks from EMFs. Originally, these concerns were mainly about the fields produced by the electric power system that supplies energy for domestic and industrial use, but more recently, the concerns have included mobile phones and other wireless devices as well. The IET has been examining the issue carefully for many years and has produced this Position Statement and Factfile to provide authoritative background information and unbiased advice on the subject.