SAGE First Interim Assessment

SAGE was the UK's Stakeholder Advisory Group on ELF EMFs.  This page covers its First Interim Assessment published in April 2007.  See more on SAGE generally, on the Government Response to the First Interim Assessment in October 2009, and on the Second Interim Assessment in June 2010.

cover of sage reportSAGE's First Interim Assessment was published in April 2007. It considers a number of generic issues, then possible precautionary measures for EMFs from three different sources: house wiring, appliances, and power lines and property.

Download the Assessment and the Supporting papers

 When Government received the SAGE Assessment, they asked the HPA for a response to it. The HPA's response is available here and the Minister's reply is here.  These were followed by the formal Government response to SAGE.

SAGE's general approach

The scientific evidence

SAGE does not assess the scientific evidence itself but identifies a range of views of the scientific evidence adopted by other review bodies. It summarises them as two positions.

  • The "WHO/HPA" view that there is a possible link between magnetic fields and childhood leukaemia. More on what HPA have said
  • The "California" view that there is a possible link between magnetic fields and a range of adverse health effects. More on what California have said

Reducing exposures where reasonable

SAGE says:


"We have adopted a principle of seeking ways to make people's exposure to electric and magnetic fields "as low as reasonably achievable." We use this phrase in its plain English sense rather than as a legally defined principle. Much of our work has been in determining what is "reasonable."

Cost-benefit analysis

SAGE considers how to determine what is "reasonable" and gives a lot of attention to cost-benefit analysis. It says:

"We recognise that cost-benefit analysis is an important tool for society in determining the most effective use of resources, and in ensuring that society does not devote so much resource to one issue that it results in more harm in other areas than the benefit it creates. It is a way of assessing the proportionality of any response to a health or safety issue. We also recognise that cost-benefit analysis is just one tool; other social or political factors, which do not lend themselves to inclusion in a cost-benefit analysis, are relevant."

SAGE gives a lot of quantitative detail on costs and benefits.

One example SAGE gives of relevant factors other than cost-benefit is public concern.

"We agree that it is right and proper for a government to give consideration to public concern when determining what action to take."

SAGE's recommendations on house wiring and appliances

House wiring

SAGE recommends a package of changes to house wiring practices. It says these should introduced for all new building and for complete rewiring of existing homes, and should be available as an option for applying to existing homes if high fields are identified. The estimated extra cost is £20 per house newly wired in this way.

The package includes:

  • Using radial power circuits instead of ring mains
  • Keeping "go" and "return" currents together
  • Keeping meter tails together
  • Require an RCD for the whole installation
  • Phase out rotating disc electricity meters
  • Provide information for householders

See more detail on these measures and how they reduce fields.

Domestic electrical appliances

(SAGE uses the terminology "equipment")

SAGE recommends:

"Equipment manufacturers should investigate whether fields could be reduced at low cost, and whether offering consumer choice of low-field appliances could be an advantageous marketing strategy"

More on fields from appliances.

SAGE's recommendation on power lines and property

SAGE makes two Recommendations and analyses an Option.

The Recommendations:

  • More information for householders
  • Rephasing of some 132 kV lines. More on phasing in general and the SAGE recommendation in particular.

The Option:

  • "Corridors" along power lines where new building would not be allowed

The "Corridors" Option

SAGE analyses an Option of introducing "corridors" round power lines. It suggests:

  • The corridor would be 60 m from the centre of the line for 400 kV and 275 kV lines, 30 m for 132 kV and 66 kV lines, and no corridor for lower voltages. These distances were chosen as the average distance for the field to fall to 0.4 µT. Various other distances have also sometimes been proposed for corridors. 
  • No new buildings would be allowed within this distance of existing power lines and no new power lines within this distance of existing buildings
  • It would apply to buildings for residential use and some other uses such as schools
  • It could be implemented, if desired, as policy rather than requiring regulation

SAGE participants were divided on whether this Option should be implemented, which is why it is an Option rather than a Recommendation. It appears that, broadly:

  • Some participants think it should not be implemented as the adverse consequences outweigh the benefits, and in particular that it fails cost-benefit analysis
  • Other participants think it should be implemented, either because the cost-benefit analysis should include adverse health outcomes other than just childhood leukaemia which may make the outcome favourable, or because factors other than just cost-benefit analysis, such as public concern, should be considered

More on the SAGE cost-benefit analysis of this option

Existing homes near power lines

SAGE says:

"Taking action on existing situations (with the exception of limited rephasing of 132 kV overhead lines as already discussed) would be more complex and more expensive and we suggest that the initial decision Government should make is whether or not to take action in relation to new construction."

more on existing homes near power lines.

See also:

Reducing your own exposure

If you decide for yourself that you want to reduce your exposure to EMFs, we provide a page with a discussion of the main options.