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Electromagnetic Field (EMF) Limits

Johan van der Sanden, Philips IP&S

1. General

The acronym EMF (Electromagnetic Fields) is widely used to express the exposure of humans to electromagnetic fields. The exposure to EMF covers a wide frequency range (0 Hz - 300 GHz). EMF is sometimes known as electromagnetic radiation (EMR) or electromagnetic energy (EME). Electromagnetic fields are present everywhere in our environment – the earth, sun and ionosphere are all natural sources of EMF.
Electric and magnetic fields are part of the spectrum of electromagnetic energy which extends from static electric and magnetic fields, mains power frequencies (50/60Hz) through radiofrequency, infrared, and visible light.

Electromagnetic Spectrum - This diagram shows the electromagnetic spectrum in the non-ionizing section. WPC Qi products are using electromagnetic waves within the marked non-ionizing area of the electromagnetic spectrum. Non-ionizing means, that the energy of those waves is too low to ionize tissues.

Electromagnetic fields are also created in any electrical appliance, including many in daily use such as refrigerators, hairdryers and computers.
Many electrical appliances don’t just create electromagnetic fields – they are functional for them to work in a proper way. Electrical toothbrushes, rechargeable remote controls and many other aplliances are using EM fields. So do wireless chargers such as those certified by the WPC.

2. Applicable limits

2.1 General

Depending on the region where the product will be placed on the market, the basic restrictions of the general public of either IEEE C95.1 2005, ICNIRP 1998 (0 Hz - 300 GHz) or ICNIRP 2010 (0 Hz - 100 kHz) are applicable. It is the responsibility of the manufacturers to ensure that they are using the corredt version of the limit sets as specified by national authorities.

2.2 ICNIRP exposure limits

In order to protect against any known health effects, the independant scientific committee (ICNIRP) [1] has published guidelines (exposure limits) for a maximum exposure. These guidelines consist of the publications from 1998 (0 Hz - 300 GHz) and 2010 (0 Hz - 100 kHz). They are based on an extensive number of related scientific publications, evaluated by the authors of the ICNIRP committee and have been reviewd up to today by more than 35 national expert committees.

ICNIRP states that: “There is no substantive evidence that adverse health effects can occur in people exposed to levels at or below the ICNIRP limits”
The ICNRIP guidelines include basic restrictions for “occupational exposure” and for “general public exposure”, see tables below. The limits for the general public are applicable for consumer applications.
Reference levels are provided for practical exposure assessment purposes to determine whether the basic restrictions are likely to be exceeded, see tables below. Compliance with the reference level will ensure compliance with the relevant basic restriction. If the measured or calculated value exceeds the reference level, it does not necessarily follow that the basic restriction will be exceeded. However, whenever a reference level is exceeded it is necessary to test compliance with the relevant basic restriction.

[1] International Commission on Non-Ionizing Radiation Protection, [ICNIRP] "Guidelines for limiting exposure to time-varying electric, magnetic, and electromagnetic fields", Health Physics April 1998, Volume 74, Number 4.

WHO research summary http://www.who.int/peh-emf/research/en/

2.2.1 ICNIRP Guidelines 1998

Basic restrictions for exposure between 0 Hz and 300 GHz.

Reference levels for exposure between 0 Hz and 300 GHz

2.2.2 ICNIRP Guidelines 2010 (0 - 100 kHz)

Basic restrictions for exposure between 0 Hz and 100 kHz

Reference levels for general public exposure between 0 Hz and 100 kHz

Reference levels for occupational exposure between 0 Hz and 100 kHz

2.3 IEEE exposure limits

Basic restrictions induced electric field applying to different parts of the body

Basic restrictions Specific Absorption Rate (SAR) for frequencies between 100 kHz and 3 GHz

Maximum permissible exposure (MPE) for exposure to head and torso between 3 kHz and 5 MHz

Maximum permissible exposure (MPE) for exposure to limbs between 3 kHz and 5 MHz




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