Overhead Lines



                 Overhead Lines

                 Overhead Lines and Ions




Overhead Lines

Electric and Magnetic Field Surveys are often required near to high voltage overhead lines.  This is because overhead lines have attracted attention from researchers since the early 1960s when the first report of general illnesses was issued.  The interest heightened in 1979 and 1993 with the publication of research reports that claimed very low levels of magnetic fields were associated with the increase in childhood leukaemia.

The type of research involved in these latter studies was Epidemiological, that is, they studied groups of people living near wires and overhead lines and compared their state of health with other groups living further away.  The research did not study or try to explain in biological terms how such effects could occur.  Biology today cannot provide an accepted biological mechanism for the causation or promotion of cancer.

Of course it does not require all the answers to be provided before concerns and fears are raised.  The electricity companies throughout Britain soon became involved in addressing the concerns of those people living near to overhead lines and other equipment. 

Looking at the picture opposite it is easy to see why many people became alarmed.  Here a builder has avoided the costs involved having this 400kV (400,000 Volt) double circuit 'Quad' line moved or raised by aligning his road with the tower (sometimes called a pylon).  The industry name 'Quad' is given to this type of construction as there are four conductors grouped together per 'phase'.  Looking along this type of line towards a tower you will see one 'earth' conductor at the very top and on each side of the tower there are three groups of four conductors. A total of 25 conductors.

The magnetic field under and close to this line exceeded the values given in the Swedish report.  However, the only established and basic facts are;

  • No-one should climb the tower.

  • No-one should fly kites.

  • There will be wind noise from the conductors and the tower.

  • There will be a crackling noise created by ionisation of the air around the conductors.

  • The use of computers using standard monitors will be impaired by the screen image flickering or wobbling.  Laptop computers will be unaffected.

  • There will be more research claiming harmful effects that attracts wide media coverage and other research that finds no cause for concern that gets very little coverage.



** See the Research page for the report on the risks of Cancer**





Overhead Lines and Ions


There has been some alarm about the role that ions may play in increasing the risk of cancer for people living near to high voltage overhead lines.  This concern originated from work carried out by Professor Henshaw of Bristol University that was used by the BBC to launch it's new Radio Four programme, 'Costing the Earth' on 21 September 2000.

Professor Henshaw's theory, put simply, is:

The high voltage overhead lines create Ions, charged particles.  These particles become attached to pollutants in the air, which in turn, become more attracted to people.  The pollutant will then stick to the skin or be breathed in.  The theory goes, once in the lung, the pollutants will cause lung cancer.

The high voltage overhead line is not itself harmful, but its presence will attract and concentrate the pollutants from car exhausts etc, and these will accumulate downwind of the overhead line.  It is claimed this effect has been missed in all previous work as all the research associated with overhead lines has looking for magnetic field effects, not electric field effects.


Wrong, the study of possible magnetic field effects resulted from work that first looked for electric field effects.  The whole subject of electric and magnetic fields (EMF) originated from reports that Russian workers in high voltage substations were suffering various maladies.  Electrical utilities around the world carried out checks to see if any such effects were present, they were not.  Swedish research on EMF first started with a study looking for electric field effects associated with high voltage overhead lines and they found no such effects.  Having had no success with electric field studies, the scientific community moved its attention to magnetic fields.

There are many other points on which Professor Henshaw's theory can be challenged.  The overwhelming consensus of the scientific community is that he is mistaken in his beliefs.  There has been some very strong and damming views expressed of both the research and the role of the BBC in creating unnecessary public alarm. 

One example is the Press Release issued by the Institute of Electrical Engineers (IEE) responding to the BBC programme:

     ".. the Bristol scientists are unwilling or unable to disclose their research methods .."

     and that

     ".. it is highly irresponsible to make sensational claims about alleged health effects, which      appear to contradict work carried out elsewhere, without publication of peer reviewed      papers ..".


The peer review process is our quality control check and should not be missed out.  We deserve to have all the checks carried out, especially where public health is concerned.  The full Press Release is reproduced below.





The IEE Press Release

   27 September 2000

POWER LINE PROGRAMME "IRRESPONSIBLE" SAYS IEE


The IEE, Europe's largest engineering professional body, strongly deplores the manner in which scientists at Bristol University have collaborated with the BBC in producing a sensational programme on the alleged harmful effects of overhead power lines on people's health, without providing adequate supporting data.

The IEE has, since 1994, been conducting a rigorous study of peer reviewed papers concerning the possible harmful effects of low level low frequency electromagnetic fields, such as those near overhead power lines.  In that time some 1600 papers have been reviewed by a panel of experts who have concluded that there is no evidence of any harmful effects.  The same conclusion was reached recently following a major epidemiological study conducted as part of the UK Childhood Cancer Study under Professor Doll from Oxford University (the Doll Report).

Scientists from Bristol University are claiming that the electrostatic fields surrounding power lines can, under certain circumstances, cause particles of pollution to become electrically charged, and the particles are then inhaled by people living near those power lines.  Such particles, it is claimed, are more likely to "stick" to the lungs, and therefore cause cancer.

The resulting number of deaths which they claim, are far higher than could be explained on the basis of published data, and no account appears to have been taken of the effects of smoking, which is well known as the major cause of cancer of the lung.  Despite requests by the IEE's experts, the Bristol scientists are unwilling or unable to disclose their research methods.  Nor have any peer review published papers been produced to support their claims.

The IEE's Chief Executive Dr Alf Roberts said that the IEE believes that it is highly irresponsible to make sensational claims about alleged health effects, which appear to contradict work carried out elsewhere, without publication of peer reviewed papers in scientific journals.  Publication via the media, without releasing the associated data and scientific methods, can only serve to cause unjustified alarm in the general public without adding to valid scientific debate.








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