This website deals with power-frequency EMFs. The scientific term for these EMFs is "Extremely Low Frequency" (ELF).
At much higher frequencies, EMFs are described as "radiofrequency" or RF. This website doesn't cover RF fields. But we provide a page of links to organisations that do cover RF EMFs. And here we summarise some of the key differences.
| Power-frequency EMFs |
Radiofrequency EMFs |
| The frequency is 50 hertz (60 hertz in the USA) and harmonics |
The frequency is hundreds of kilohertz upwards, all the way up to tens of gigahertz - millions or tens of millions times higher than power frequencies |
| They are produced by mains electricity - power lines, substations, electricity in the home, appliances |
They are produced by many different technologies - broadcast TV and radio, cell phones and other radio communications, wi-fi, wi-max, Tetra, etc etc |
| There haven't been many major changes in the technologies producing them for many decades |
The technologies are changing all the time |
| The electric and magnetic fields are separate phenomena |
The electric and magnetic fields are coupled together as radiation |
| They can induce currents in the body but do not cause heating |
They can cause heating in the body |
| They tend to be relatively straightforward waveforms (a sine wave with only a few harmonics) |
The modulations used to transmit signals mean the waveforms are highly complex |
There are some similarities as well though:
- neither causes ionisation in body tissues
- both are the subject of exposure limits
- both are now inextricably linked with modern societies and lifestyles
