Keith G. Richens
Cranage EMC & Safety
Oakley, Shropshire, UK
Introduction
Electromagnetic fields (EMF) are universally present in the everyday environment, including workplaces and public areas. Measurements are made to identify and characterise them to ensure that people are not exposed to fields that could potentially cause injury or adversely affect health.
Standards and Regulations Overview
The European Parliament and the Council of the European Union published in the Official Journal (OJ) on 30th July 1999, a recommendation (1999/519/EC) on the limitation of exposure of the general public to electromagnetic fields.
A European Standard for determining EMF in the space around household and similar electrical appliances was implemented at UK national level on 1st February 2004. This standard, which provided a method to show compliance with the above recommendation, is currently listed in the framework of implementation of Council Directive 73/23/EEC. It also deals with appliances which are accessible to the general public outside the home, eg. equipment used in hotels, shops, farms, etc.
From 1st February 2006, magnetic field evaluation to EN50366 will become mandatory for household and similar electrical appliances within the scope of the Low Voltage Directive 73/23/EEC.
A generic standard (EN50392) relating to human exposure to electromagnetic fields for all electronic and electrical apparatus comes into force on 1st October 2006. This standard was implemented in the UK on 1st October 2004 but is not currently required for demonstrating compliance with European Directives.
European Directive (2004/40/EC) was published in the OJ in May 2004 on the minimum health and safety requirements regarding the exposure of workers to the risks arising from physical agents (electromagnetic fields). Compliance with this Directive is mandatory from 30th April 2008. This Directive will make it necessary for employers to introduce measures to protect workers from the risks associated with EMF. Limits and action values are specified for measurement purposes along with recommendations concerning risk management, health surveillance, and information and training for those working in exposed conditions.
Measurements specified in 2004/40/EC need not be carried out in workplaces open to the public if an evaluation was performed in accordance with Council recommendation 1999/519/EC.
The European Commissions Scientific Steering Committee has endorsed advice on matters concerning electromagnetic exposure given by the International Commission on Non-Ionizing Radiation Protection (ICNIRP)
In the United Kingdom, The Health Protection Agency, via National Radiological Protection Board (NRPB), has recommended the use of ICNIRP guidelines for restricting occupational and general public exposure to EMF including static magnetic fields.
Exposure Limits and Action Values
The frequencies of interest published in 2004/40/EC cover all eventualities, ranging from 0Hz to 300GHz, for static magnetic fields and EMF.
Excluding radio-frequency transmitting devices such as mobile phones and telemetering devices, production areas and general environments utilising 50Hz supplies can be adequately surveyed using instruments with a reduced bandwidth of 0Hz to 400kHz. This frequency range is specified in the electrical appliance standard EN50366.
Employer Obligations
Risk Management
i) If the limits are exceeded, the employer must devise and implement an action plan comprising technical and / or organisational measures intended to prevent exposure exceeding the action values
ii) In places where workers could be exposed to EMF exceeding the action values, appropriate signs must be displayed in accordance with Directive 92/58/EEC: Requirements for the use of safety and / or health signs at work.
iii) Workers must not be exposed to EMF above the action values specified in 2004/40/EC. If, despite measures taken by the employer to comply with this Directive, the action values are exceeded, the employer must take immediate action to reduce exposure and identify the reasons why the action values have been exceeded. Prevention and protection measures must be amended to prevent them being exceeded again.
Worker Information and Training
The employer must ensure that workers who are exposed to risks from EMF at work and/or their representatives receive information and training to minimise risks from exposure.
Health Surveillance
Where exposure above the action values is detected, a medical examination must be made available to workers concerned.
Cardiac Pacemakers
Concerning wearers of medical implants, adherence to the exposure limits and action values specified in 2004/40/EC may not necessarily avoid operational problems with these devices. Interference effects on the functioning of medical devices such as metallic prostheses, defibrillators, cochlear implants and especially cardiac pacemakers may occur at levels below the action values. The Directive recognises this possibility and recommends that appropriate precautions and protective measures should be taken, but it falls short of specifying any investigation limits for measurement purposes.
ICNIRP produced guidelines in January 1994 on limits of exposure to static magnetic fields relating to cardiac pacemakers. Tests at that time on a large sample of pacemakers indicated the majority were unlikely to be affected in static fields less than 0.5mT.
European and British Standards specify tests for implantable cardiac pacemakers to include immunity against static and time varying electromagnetic fields (see BS 6902: Part 1: Supplement 1: 1996 EN50061:1988 +A1:1995). At high frequencies, the implanted pacing lead is stated to act as an antenna. At mains frequencies, currents flowing through the torso are stated to be concentrated by the lead. In summary, exposure of a pacemaker to an electromagnetic field may cause fibrillation, local heat damage and / or abnormal pulse behaviour.
Pacemakers are specifically tested for immunity to static magnetic fields in the range 1mT to 10mT.
Tests on pacemakers for determining immunity to time varying electromagnetic fields are based on direct injection of voltages which do not correlate to field measurements in free space.
Current advice on limiting exposure to electromagnetic fields published by the National Radiological Protection Board (NRPB) is not concerned with possible interference effects with implantable medical devices such as pacemakers.
No viable information is available at the present time relating to limits of exposure to time varying electromagnetic fields for wearers of medical implants.
Examples of Documents with Statements Referring to EMF
a) EN60950: 1992: Safety of Information Technology Equipment
Page 10 Radiation hazards, stated – If equipment emits some forms of radiation, requirements are necessary to keep OPERATOR and SERVICE PERSONNEL exposures to acceptable levels.
The types of radiation that can be encountered are sonic, radio frequency, infra-red, high intensity visible and coherent light, ultraviolet, ionizing, etc.’
b) EN60950: 2000: Safety of Information Technology Equipment
Page 22 Para 0.2.6 Radiation, stated – Hazards to USERS and to SERVICE PERSONNEL may result from some forms of radiation emitted by equipment.
Examples are sonic (acoustic), radio frequency, infra-red, ultraviolet and ionizing radiation, and high intensity visible and coherent light (lasers).
Examples of measures to reduce such hazards include:-
– limiting the energy level of potential radiation sources
– screening radiation sources
– provision of SAFETY INTERLOCKS
– provision of markings to warn USERS where exposure to the radiation hazard is unavoidable
c) EN60947-4-2:1996: Low-voltage switchgear and controlgear. Part 4. Contactors and motor-starters. Section 2. AC semiconductor motor controllers and starters.
Page 12 Para 3.2.3 electromagnetic disturbance defined as: Any electromagnetic phenomenon which may degrade the performance of a device, equipment or system, or adversely affect living or inert matter.
d) EN60204-1:1997: Safety of machinery – Electrical equipment of machines – Part 1. General requirements. Page 21 Para 4.4.2 Electromagnetic compatibility (EMC), stated – The equipment shall not generate electromagnetic disturbances above levels that are appropriate for its intended places of use (electromagnetic disturbances not defined in this standard, but presumed to be linked with (c) above)
e) EN60974-10:2003: Arc welding equipment – Part 10. EMC requirements.
Page 14 Annex A (informative) Installation and use. Para A.2 Assessment of area: stated – Before installing arc welding equipment the user shall make an assessment of potential electromagnetic problems in the surrounding area. The following shall be taken into account:-
Sub-paragraph e) the health of the people around, for example the use of pacemakers and hearing aids.
Conclusion
EMF related references have appeared in product safety and EMC standards for several years, so it should be no surprise to learn that household electrical products must now be tested for magnetic field emissions in order to fully comply with the EU Low Voltage Directive. The regulatory wedge is driven all the way to the workplace in 2008 making it necessary for employers in Europe to introduce measures to protect workers from the risks associated with EMF. Between now and then, more research will be needed to determine limits of exposure for wearers of medical implants.
Author
Keith G Richens founded Cranage EMC & Safety with his wife Pauline in 1992. He is a Chartered Engineer with over 25 years experience of electrical and electronic product design. Indentured with the United Kingdom Atomic Energy Authority, he graduated in 1977 from the University of Manchester, and has since held various positions in technical, managerial and consultancy roles for product manufacturing companies in the UK.
References
1) Cardiac pacemakers. Part 1. Specification for implantable cardiac pacemakers. Supplement 1. Electromagnetic compatibility. BS 6902: Part 1: Supplement 1: 1996 EN50061:1988 +A1:1995
2) EN50392:2004. Generic standard to demonstrate the compliance of electronic and electrical apparatus with the basic restrictions related to human exposure to electromagnetic fields (0Hz – 300GHz)
3) Documents of the NRPB. Volume15 No.2:2004: Advice on Limiting Exposure to Electromagnetic Fields (0 – 300GHz)
4) ICNIRP Guidelines on Limits of Exposure to Static Magnetic Fields. Health Physics January 1994, Volume 66, Number 1
5) EN50366:2003 Household and similar electrical appliances – Electromagnetic fields – Methods for evaluation and measurement
6) 1999/519/EC Council Recommendation of 12th July 1999 on the limitation of exposure of the general public to electromagnetic fields (0Hz to 300GHz)
7) 2004/40/EC Directive of the European Parliament and of the Council of 29th April 2004 on the minimum health and safety requirements regarding the exposure of workers to the risks arising from physical agents (electromagnetic fields).
8 ) 73/23/EEC: Council Directive of 19 February 1973 on the harmonization of the laws of Member States relating to electrical equipment designed for use within certain voltage limits (Official Journal L 77 of 26 March 1973)
