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Electric and magnetic fields and health

index/glossary | EMFs At A Glance | EMF The Facts (pdf)
  • What are EMFs
    • Terminology – an introduction
    • Electric fields
    • Magnetic fields
    • Units for measuring EMFs
    • Measuring and calculating EMFs
      • “EMF Commercial”
    • Adding fields together
    • Radiofrequencies
    • Screening EMFs
  • Sources
    • Overhead power lines
      • Fields from specific power lines
        • 400 kV
        • 400 kV – specific cases
        • 275 kV
        • 132 kV
        • 66 kV
        • 33 kV
        • 11 kV
        • 400 V/230 V
        • Replacing a 132 kV line with a 400 kV line
      • Summaries of fields from all power lines
      • Factors affecting the field from a power line
        • Voltage
        • Current
        • Clearance
        • Height above ground
        • Conductor bundle
        • Phasing
        • Balance between circuits
        • Balance within circuit
        • Ground resistivity
        • Two parallel lines
      • Calculating and measuring fields from power lines
        • Geometries of power lines
        • Raw data
        • On-line calculator
      • Fields from power lines – more detail on the physics
        • Field lines from a power line
        • The direction of the field from a power line
        • Power law variations in the field from a power line
      • Statistics of power line fields
    • Underground power cables
      • Different types of underground cable
      • Fields from cables in tunnels
      • Gas Insulated Lines (GIL)
      • Underground cables with multiple conductors
      • Effect of height on fields from underground cables
      • Screening fields from underground cables
    • Low-voltage distribution
      • UK distribution wiring
      • USA distribution wiring
    • House wiring
    • Substations
      • National Grid substations
        • Static Var Compensators
      • Sealing-end compounds
      • Distribution substations
      • Final distribution substations
        • Indoor substations
    • Transport
      • EMFs from electric trains (UK)
      • EMFs from cars
    • Appliances
    • Electricity meters
      • Smart meters
      • Traditional meters
    • Occupational exposures
      • Live-line work
      • Static Var Compensators
      • Occupational exposures on pylons
    • Field levels and exposures
      • Personal exposure
      • Other factors that vary with magnetic fields
      • Fields greater than 0.2 or 0.4 µT
    • Screening EMFs
      • Screening fields from underground cables
      • EMF Reduction Devices
  • Known effects
    • Induced currents and fields
    • Microshocks
      • Control of microshocks in the UK
      • Microshocks from bicycles
      • Bees and microshocks
    • EMFs and medical devices
      • Standards relating to pacemakers and other AIMDs
    • Effects of EMFs on equipment
  • Research
    • Types of research
    • Epidemiology
    • Animal and laboratory experiments
    • Mechanisms
    • Specific studies
      • UKCCS
      • CCRG
      • French Geocap study
      • CEGB cohort
      • Imperial College study
  • Current evidence on health
    • Childhood leukaemia
      • Survival from childhood leukaemia
      • Childhood leukaemia and Downs
      • Childhood leukaemia and night-time exposure
      • The “contact current” hypothesis
    • Other health effects
    • Scientific review bodies
      • WHO
      • IARC
    • Electric fields and ions
    • Comparing EMFs to other issues
  • Exposure limits for people
    • Limits in the UK
    • Limits in the EU
    • Limits in the USA
    • Limits in the rest of the world
    • Limits from specific organisations
      • ICNIRP 1998
      • ICNIRP 2010
      • NRPB 1993
      • NRPB 2004
      • EU 2004
      • EU 2013
  • Policy
    • UK policy
      • Power lines and property – UK
    • Compliance with exposure limits
    • European EMF policy
    • Precaution
    • SAGE
      • SAGE First Interim Assessment
        • Government response to SAGE First Interim Assessment
      • SAGE Second Interim Assessment
        • Government response to SAGE Second Interim Assessment
        • SAGE Second Interim Assessment – the full list of recommendations
  • Finding out more
    • EMF measurement and commercial services
    • Links
    • Literature
    • Contact us
  • Static fields
    • Static fields – the expert view
You are here: Home / Known effects / EMFs and medical devices

EMFs and medical devices

Pacemakers, defibrillators, etc: are they affected by power lines?

Implanted medical devices are pacemakers, implanted defibrillators and similar. People with these devices may be particularly concerned about interference from EMFs, so we give quite a lot of detail here. See also a simpler summary and for information on how EMFs interfere with other equipment.

Advances in medical technology over the past 50 years have resulted in an increased number of patients who have active implantable medical devices (AIMDs). There are no longer the constraints there used to be on these patients and many are able to live active, full lives, including returning to full-time work. There are however electric and magnetic fields present in the environment, which can potentially interact with these devices.

What are Active Implantable Medical Devices?

An active implantable medical device (AIMD) is any medical device which is intended to be totally or partially introduced, surgically or medically, into the human body, and which is intended to remain after the procedure. The commonest are pacemakers and defibrillators (together described as "implanted heart devices") but there are others as well.

All usually comprise of a small battery-powered box with electronic circuitry and leads, electrodes and/or sensors, which detect a biological function or deliver a stimulus.

The rest of this page deals with pacemakers and defibrillators - see a separate page on cochlear implants.

Interference with pacemakers and intra-cardiac defibrillators (ICDs) 

The heart produces electrical signals or action potentials, which need to be reliably detected by pacemakers’ and ICDs’ sensing leads.  External electric and magnetic fields can induce signals on these sensing leads that prevent the device working properly. Any effects are temporary and manufacturers advise there should be no permanent harm to the device.

If this happens to a pacemaker, it usually reverts to constant pacing mode.  A defibrillator could in theory send a shock when one was not needed, or possibly be inhibited from providing a shock when one is needed (the evidence is divided on this).  See more on the consequences of interference if it does occur.  Any interference with an implanted heart device is potentially serious. 

Does interference occur in practice?

Neither the Medicines and Healthcare products Regulatory Agency (MHRA) nor National Grid are aware of any instance of a power line interfering with a correctly fitted modern electronic implantable device such as a pacemaker or ICD.  See more detail on this.

Thus there is considerable confidence in saying that based on the absence of reported incidents, power lines do not appear to interfere with implanted heart devices.

Can interference happen in theory?

Implanted medical devices are governed by Regulations and Standards.  These require the devices to be immune from interference up to, basically, the general public reference levels from the EU Recommendation on exposure limits.  Manufacturers typically test devices up to 100 µT and 6 kV/m.  This pretty well guarantees there will be no interference from magnetic fields, but leaves a theoretical possibility of interference from electric fields.  Scientists have produced interference in laboratory settings, as opposed to real-life settings.

Advice to patients from manufacturers

Manufacturers of potentially affected implanted devices often provide information on electromagnetic interference.  This typically covers a range of sources.  Advice often includes avoiding letting the implanted device get too close to certain sources of fields such as some household appliances, some walkie-talkies and similar transmitting devices, etc.  Some manufacturers’ literature does not mention high-voltage power lines, some say that exposure in public areas should not give interference, some advise not spending extended periods of time close to power lines.

For example, Medtronic state:

“Power lines - high voltage
Low risk of affecting Pacemaker or ICD when walking, driving underneath, or living in a house or building nearby. Individuals servicing high voltage power lines have the potential for Pacemaker reversion or ICD shock. For this work environment contact Medtronic Technical Services to review specific concerns”

No manufacturers appear to regard any hazard as sufficient to require a prohibition on approaching high-voltage power lines.

The regulatory position

The relevant UK regulatory body are the Medicines and Healthcare products Regulatory Agency (MHRA).  They do not regard power lines as a significant risk for people with implanted heart devices given the absence of any reports of interference occurring to date.

This conclusion is restated in the formal Government statement on policy for power lines, National Policy Statement EN-5:

"[MHRA] does not consider that transmission line EMFs constitute a significant hazard to the operation of pacemakers."

NPS EN-5 2.10.7

NPS EN-5 specifies that power lines must comply with the relevant exposure guidelines, but does not impose any extra requirements relating to implanted medical devices.

See also:

  • the concequences of interference
  • regulations and standards
  • manufacturers of medical devices
  • interference with cochlear implants

Latest news

  • New publication on cancer incidence from the UK electricity industry Cohort Study August 27, 2019
  • How has the reported risk for childhood leukaemia changed over time? February 11, 2019
  • Media stories about microshocks in children’s playground September 10, 2018
  • New studies on leukaemia and distance from power lines June 1, 2018
older news

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To contact the electricity industry’s EMF Unit Public Information Line (UK only):
telephone 0845 7023270 or email [email protected].

See Contact us for more contact details including our privacy policy.

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Navigation
  • What are EMFs
    • Terminology – an introduction
    • Electric fields
    • Magnetic fields
    • Units for measuring EMFs
    • Measuring and calculating EMFs
      • “EMF Commercial”
    • Adding fields together
    • Radiofrequencies
    • Screening EMFs
  • Sources
    • Overhead power lines
      • Fields from specific power lines
        • 400 kV
        • 400 kV – specific cases
        • 275 kV
        • 132 kV
        • 66 kV
        • 33 kV
        • 11 kV
        • 400 V/230 V
        • Replacing a 132 kV line with a 400 kV line
      • Summaries of fields from all power lines
      • Factors affecting the field from a power line
        • Voltage
        • Current
        • Clearance
        • Height above ground
        • Conductor bundle
        • Phasing
        • Balance between circuits
        • Balance within circuit
        • Ground resistivity
        • Two parallel lines
      • Calculating and measuring fields from power lines
        • Geometries of power lines
        • Raw data
        • On-line calculator
      • Fields from power lines – more detail on the physics
        • Field lines from a power line
        • The direction of the field from a power line
        • Power law variations in the field from a power line
      • Statistics of power line fields
    • Underground power cables
      • Different types of underground cable
      • Fields from cables in tunnels
      • Gas Insulated Lines (GIL)
      • Underground cables with multiple conductors
      • Effect of height on fields from underground cables
      • Screening fields from underground cables
    • Low-voltage distribution
      • UK distribution wiring
      • USA distribution wiring
    • House wiring
    • Substations
      • National Grid substations
        • Static Var Compensators
      • Sealing-end compounds
      • Distribution substations
      • Final distribution substations
        • Indoor substations
    • Transport
      • EMFs from electric trains (UK)
      • EMFs from cars
    • Appliances
    • Electricity meters
      • Smart meters
      • Traditional meters
    • Occupational exposures
      • Live-line work
      • Static Var Compensators
      • Occupational exposures on pylons
    • Field levels and exposures
      • Personal exposure
      • Other factors that vary with magnetic fields
      • Fields greater than 0.2 or 0.4 µT
    • Screening EMFs
      • Screening fields from underground cables
      • EMF Reduction Devices
  • Known effects
    • Induced currents and fields
    • Microshocks
      • Control of microshocks in the UK
      • Microshocks from bicycles
      • Bees and microshocks
    • EMFs and medical devices
      • Standards relating to pacemakers and other AIMDs
    • Effects of EMFs on equipment
  • Research
    • Types of research
    • Epidemiology
    • Animal and laboratory experiments
    • Mechanisms
    • Specific studies
      • UKCCS
      • CCRG
      • French Geocap study
      • CEGB cohort
      • Imperial College study
  • Current evidence on health
    • Childhood leukaemia
      • Survival from childhood leukaemia
      • Childhood leukaemia and Downs
      • Childhood leukaemia and night-time exposure
      • The “contact current” hypothesis
    • Other health effects
    • Scientific review bodies
      • WHO
      • IARC
    • Electric fields and ions
    • Comparing EMFs to other issues
  • Exposure limits for people
    • Limits in the UK
    • Limits in the EU
    • Limits in the USA
    • Limits in the rest of the world
    • Limits from specific organisations
      • ICNIRP 1998
      • ICNIRP 2010
      • NRPB 1993
      • NRPB 2004
      • EU 2004
      • EU 2013
  • Policy
    • UK policy
      • Power lines and property – UK
    • Compliance with exposure limits
    • European EMF policy
    • Precaution
    • SAGE
      • SAGE First Interim Assessment
        • Government response to SAGE First Interim Assessment
      • SAGE Second Interim Assessment
        • Government response to SAGE Second Interim Assessment
        • SAGE Second Interim Assessment – the full list of recommendations
  • Finding out more
    • EMF measurement and commercial services
    • Links
    • Literature
    • Contact us
  • Static fields
    • Static fields – the expert view