What are electromagnetic fields? How do they affect people? How can they be assessed? The questions are answered here.

What are electromagnetic fields? Electromagnetic fields (EMF) are all around us, but are invisible to the naked eye. They can be man-made (e.g., power lines, TV antennas, mobile phones) or originate from a natural source (earth’s magnetic field, thunderstorms etc.). They tend to be characterised in terms of their frequency or wavelengths.

At low frequencies, electric fields are present close to charged conductors. Magnetic fields occur in situations where you have movement of an electric charge; an electric motor would be an example of this.

At high frequencies, radio transmitters and TV antennas are examples of equipment that produce electromagnetic fields in the radiofrequency (RF) range. Additionally, examples of devices which generate electromagnetic fields in the GHz region are microwaves, mobile phones and Wi-Fi routers.

The intensity can be expressed in terms of the electric field strength in volts per metre (V m-1) or power density in watts per square metre (W m-2)

How do they affect people? Low frequency fields will induce electric fields and circulating currents in the human body. The strength of these induced fields and currents will be dependent on the intensity and frequency of the external field, the conductivity of the particular tissue within the body and the distance the body is from the source.

Biological effects of human exposure to low frequency fields can be peripheral nerve/muscle stimulation and faint visual sensations (magneto-phosphenes). Additionally, problems performing mental tasks along with adverse effects on reproduction and development when exposed to ELF magnetic fields have been reported.

At high frequencies, the recognised adverse health effect is the heating of human tissues resulting in heat stress, although other non-thermal health effects have been documented. The two tissue types regarded as most susceptible to thermal injury are the eye and the testes.

How can EMFcomp Limited help? EMFcomp can measure, model or just provide advice on human exposure to electromagnetic fields. In particular, EMFcomp use computer models of (i) electromagnetic field propagation in tissues and (ii) the human body to calculate the absorption of electromagnetic fields in people.

Results generated by computational modelling of electromagnetic field interactions with the body enable you to protect against adverse health effects associated with exposure to low and high frequency fields.

Electromagnetic fields are all around us, but cannot be seen or heard.