We give some basic information on EMFs (what they are, what they do) here.
Electric and magnetic fields (EMFs) are produced as an inherent consequence of the use of electricity. They represent the region around an electrical source – a conductor with a voltage or current – where its influence can be detected. The two fields and their relationship with each other are governed by a set of physics equations called Maxwell’s Equations. Broadly speaking, electric fields are produced by voltages and magnetic fields are produced by currents.
EMFs have the same frequency as the electrical source producing them. We often divide EMFs into two broad frequency ranges. Power frequency EMFs are produced by electric power systems – generation, transmission and distribution, and use of electricity – and have the same frequency, the mains frequency, 50 Hz in Europe and 60 Hz in the USA. Radio-frequency EMFs are produced by radio-frequency sources – broadcast TV and radio, mobile phones, wifi technologies, microwaves, other communication systems. Radio-frequency EMFs range from hundreds of kiloherz, through the hundreds of megaherz used by many communication systems, up to gigaherz used by some newer technologies.
When considering health effects of EMFs, we need to consider both relatively high field strengths and relatively low field strengths.
At high field strengths, EMFs can undoubtedly have effects on humans, and if the field strength is high enough, those effects can be harmful. Power-frequency EMFs can cause interference with nerves, and radio-frequency EMFs can cause heating. It is these “acute” effects that are protected against by exposure limits.
At lower fields strengths, too low for these acute affects, there is some controversy. For both power-frequency and radio-frequency EMFs, there are suggestions of health effects from prolonged exposure – principally various types of cancer. By normal scientific standards, these effects are not established, indeed we often say that the weight of evidence is against these effects, but it is the possibility of these effects that is of concern for some members of the public.
EMFs are controlled by exposure limits. There are separate exposure limits for workers and for the public, and the method for implementing them in the UK is different, but they both originate with the same independent body of international experts, the International Commission on Non-Ionizing Radiation Protection (ICNIRP). Those for workers are enshrined in Regulations that are legally binding on employers, and any employer has a legal duty to have assessed EMFs and taken any necessary actions. Those for the public are not legally binding, but they are set out in policy statements and codes of practice, and new infrastructure projects should not get the necessary consents unless they can demonstrate compliance.
Occupational exposures in the UK are governed by the Control of Electromagnetic Fields at Work Regulations 2016. These place a duty on all employers to have assessed EMFs. For the vast majority of employers, the conclusion will be that there are no sources of exposure big enough to trigger further action. But if you identify any sources producing high-enough fields, further actions are triggered, to do with assessment, documentation, communication, and control.
At EMF Scientific, we have been through this process with the electricity industry and with other clients. Feel free to have a chat with us about whether we can help you – we are adept in finding ways to comply while avoiding having to take expensive action!
As we said above, there are no regulations enforcing exposure limits for the public. But there is a requirement on some types of new infrastructure projects to demonstrate compliance before they can get Consent to proceed, and an expectation that consultation will take place. This is set out in quite a complex set of Policy Statements and Codes of Practice. Again, we’d be happy to talk to you about what’s involved. We understand that managing EMFs is not just a specialist technical issue, it’s a risk-management and risk-communication issue as well.
Anything that uses electricity produces EMFs.
At power frequencies, attention often focuses on high-voltage overhead power lines. These produce higher fields directly underneath them, but the field drops off to the sides. A home within 50 m, or maybe 100 m, may get an elevated field from the power line; at any greater distance, the power line probably won’t be significant.
If there’s not a nearby power line, magnetic fields in homes usually come from low-voltage distribution. There are localised elevated fields close to electrical appliances, but only within, usually, less than a metre.
At radio-frequencies, the biggest exposures usually come from sources held close to the body, most obviously, mobile phones. Other sources that are not operated close to the body – broadcast TV and radio, wifi, bluetooth, smart meters, mobile phone base stations, any other cellular communication systems – tend to produce lower exposures.
For workers, who may get close to power-frequency sources such as welders, NDT equipment, induction heaters, or close to radio-frequency sources by working on antennas, these can also produce quite high exposures.