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Electric and magnetic fields and health

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    • Field levels and exposures
      • Personal exposure
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      • Fields greater than 0.2 or 0.4 µT
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You are here: Home / Sources / Field levels and exposures / Personal exposure

Personal exposure

Why is personal exposure different to the background field?

Most measurements in epidemiological studies and most measurements made in homes have measured the field at one or more specific places, away from appliances; that is, the measurements are of the background field. Ignoring for the moment variations of field with time, a person moving around a home experiences a varying field, partly because the background field varies from place to place, and partly because of fields from appliances and other local sources.

What do we know about personal exposure?

Various measurements have been made by asking people to wear personal-exposure monitors and also measuring the background field in their homes. Average personal exposures are usually bigger than measurements of background field in the same home. The ratio in eight studies ranged from 1.09 to 2.3 with an average of 1.4. Recent work in the USA, although not directly comparing personal exposures to fields measured in homes, found a geometric-mean personal exposure of 0.09 microtesla (µT) in one thousand people, consistent with exposures being a few tens of percent higher than fields measured in homes. Simplistically, this can be thought of as the contribution from appliances (and any other local sources within the home).

How much do appliances add to personal exposure?

The contribution of appliances to exposure will vary with background field, because the higher the background field, the smaller the physical area around an appliance in which its field is significant. It is possible to create models of these effects and fit them to available data. In the UK the conclusion is that, on average, appliances contribute one-third of exposure (in accord with the simplistic approach already mentioned). The actual fraction is roughly 50% for a home at the tenth percentile of the distribution of background fields, 10% for a home at the ninetieth percentile, and just 3% for a high-field home such as might be found near a transmission line.

Example of an exposure measurement

This graph shows the reading on a personal exposure monitor worn by an adult for one day, with some of the sources of exposure marked.  The peak exposure (from the electric drill) was 149 µT; the average exposure was 0.11 µT.

 plot of personal exposure over a day

 

 

See also:

  • Field levels in the UK
  • Other sources of EMFs

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].

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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