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Types of EMF and Common Sources

Updated: Mar 6

There are two most common types of electromagnetic fields we get exposed to in our homes. Low-frequency EMF and radiofrequency EMF. We will go into more detail about each type later. These two types of EMF cover the vast majority of equipment that we could be exposed to in our day to day life. Both types put together, cover the frequency range of 1Hz-300GHz.

LOW-FREQUENCY EMF (LF EMF)

1 Hz - 100 kHz

Low Frequency (LF) is the abbreviation used for low frequency time-varying electric and magnetic fields, which describes that part of the electromagnetic spectrum comprising the frequency range from 1 Hz to 100 kHz.

LF fields have two components: an electric field due to an electric charge, and a related magnetic field. Magnetic fields only occur when an electric current is flowing. The electric component is measured in volts per meter (V/m). The magnetic component is measured in amperes per meter (A/m) and expressed as a flux density in tesla (T) or in some countries in gauss (G).

LF fields are mainly related to the electric power supply, through the generation, distribution, and use of alternating current (AC). The frequency used for this purpose is usually 50 or 60 Hz depending on the country in question. In daily life, people are exposed to LF fields around electric appliances and electronic devices mostly in the home and at work. Power lines, substations, and underground wires are also a source of LF fields.

Low-frequency EMF doesn't expand or travel, it only exists within a certain perimeter of the source. As a result of that, the distance and voltage are crucial when conducting a risk assessment. On the other hand, LF EMF cannot be shielded or deflected. The only way to reduce exposure to a low-frequency EMF is to either switch off the source or remove yourself from the electromagnetic field.

RADIOFREQUENCY EMF

100 kHz - 300 GHz

“Radiofrequency Electromagnetic Field” (RF EMF) is the term used to describe the part of the electromagnetic spectrum comprising the frequency range from 100 kHz to 300 GHz.

Within this frequency range, the electric and the magnetic fields, which together make up the electromagnetic fields, are interrelated and considered jointly for measurements. RF EMF exposure is usually measured in volts per meter (v/m).

RF EMFs are used in a variety of technologies, most widely for communication purposes (e.g. mobile phones, base stations, Wi-Fi, 5G, radio, TV, security devices), and also in medicine (e.g. Magnetic Resonance Imaging (MRI) equipment), for heating purposes (e.g. microwave ovens) and wireless power transfer.

RF EMF travels and expands, however, it can be absorbed by objects and different types of materials, it also deflects from certain types of surfaces. This means that whilst RF EMF reaches further into the distance than LF EMF, it can be shielded. To measure and potentially shield RF EMF can be tricky as many factors have to be taken into consideration when conducting an EMF test.

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