A number of devices are available on the market to reduce EMF exposure. At 50 Hz, the frequency our electricity supply operates at, an electric and magnetic field is produced each with differing physical properties. The electric fields are easily screened, and our homes actively shield these fields. Magnetic fields are much harder to screen. Advice on screening these fields can be found here
A number of devices are available on the market which claim to reduce EMF exposure within the home. It is unclear how or if these devices operate as advertised.
Public health England provide the following advice on such devices
There are some devices on the market which claim to reduce or eliminate electric and magnetic fields in the home. Such devices can be costly and should be treated with caution as they may not reduce the fields at all. In general electric fields can be shielded easily but it is more difficult to screen magnetic fields with everyday materials.