Your basket
is empty
EMFields FAQ
Frequently Asked Questions on Electromagnetic Fields


  • Go to section - I live in another country, can you ship to me, and how much will it cost?
  • Go to section - How far away is safe?
  • Go to section - Are phones with low SARs safer?
  • Go to section - Are Digital Cordless Phones (DECT) dangerous?
  • Go to section - What is the best way to wire a house to reduce electromagnetic fields in the home?
  • Go to section - Why does my Acoustimeter have problems picking up WiFi/wLan in some places?
  • Go to section - I don't want a WiFi connection to broadband internet - what options do I have?
  • Go to section - I have more than one computer and want them all to be able to use the internet - do I have to use WiFi?

I live in another country, can you ship to me, and how much will it cost?

We currently only ship directly to the United Kingdom. If you live elsewhere in the world, please see our list of international stockists.

How far away is safe?

This is a question we are often asked and, unfortunately, there is no easy answer. The research into the health effects of electric and magnetic fields (EMFs) from these structures has primarily focussed on field levels rather then distance.


Powerlines, which are part of the electricity distribution system, come in various sizes (voltages) from 400 kilovolts (kV) (largest) to 230 volts (smallest). On the whole, the higher the voltage of the line, the higher the EMFs and the further you have to be away for the fields to drop away to a background level.

Health research since the major 1979 study by Nancy Wertheimer and Ed Leeper [1], has concentrated largely on childhood leukaemia. The World Health Organisation classified extremely low frequency electromagnetic fields (ELF EMFs such as from powerlines and electric appliances) as possibly carcinogenic (cancer causing). Increased risk of leukaemia is now recognised internationally as being linked with magnetic field levels of 0.3 microtesla [2,3]. Other childhood and adult cancers [4,5,6,7,8], clinical depression, suicide, miscarriage, and other reproductive problems [9,10,11,12] and some forms of dementia have also been linked to EMF exposure [13,14,15,16].

There is much more information about the health effects of EMFs from powerlines in the free article "Powerfrequency EMFs and Health", with lots of listed and detailed research studies supporting our conclusions. We have found that about half of UK homes can have high electric fields due to the way the house wiring is done. High electric and magnetic fields together multiply the risk of serious ill health [5,6].

The only way to know for sure whether you are in levels of EMF below those at which health effects have been found, is to measure them. A suitable meter to measure the fields is the EMFields PF5 meter available for hire, and which comes with easy to follow instructions and comparisons with the levels that research has shown are linked to ill-health.

Substations or transformers

Substations generate low frequency EMFs such as those which are found near powerlines. Magnetic fields can extend out for some distance, depending on the size of the substation and the type of demand for electricity that it supplies. Underground cables run from the substation to the house, businesses, etc. that it supplies. The cables give off very high levels of magnetic field close by. This can be a particular problem for houses with small or no front gardens, or where the cables pass near the garden. The way that substations are connected can sometimes give rise to 'net' currents which can produce very high fields indeed in the houses between them. The electricity supply is unaffected and the electricity company does not usually see the high fields as a problem.

Mobile phone masts or base stations

High frequency EMFs, or microwaves, are radiated from mobile phone masts. These can cover a few metres, or several kilometres. How far depends on a number of factors. These will include

The number of operators, the height of the base station, the power of the antennas, the direction of the antennas, the physical and / or electronic uptilt or downtilt of the antennas, the quality of equipment, the local geography, the type of buildings and building structures in the immediate area.

It is impossible to determine the amount of exposure in any one place based only on the distance to the nearest mast (or mast complex). The only way to find out for certain is to measure the strength of the field in volts per metre and the amount of pulsing microwaves. The Acoustimeter, available to hire from EMFields indicates the level of radiofrequency radiation (RF) and the pulsing of the transmission, both in lights and as a digital readout. It is easy to use, comes with instructions and enables you to see what you and your family are exposed to.

Many people report very debilitating health symptoms as a result of living near mobile phone base stations [17,18,19,20,21] including an increased risk of cancer [22,23]. The World Health Organisation have classified radiofrequency electromagnetic fields (RF EMFs, such as from base stations, cordless phones and wireless internet) as a class 2B carcinogen). It is not just a psychological effect as birds and other creatures have been affected badly [24].

The evidence increases, but finding unexposed populations to compare with is getting more difficult. Sometimes protection is the best and only option.


[1] Wertheimer N & Leeper E, (1979) Electrical Wiring Configurations and Childhood Cancer, American Journal of Epidemiology 109(3): 273-284
[2] Greenland S et al, (2000) A pooled analysis of magnetic fields, wire codes, and childhood leukemia, Childhood Leukemia-EMF Study Group Epidemiology 11(6):624-34
[3] Ahlbom A et al, (2000) A pooled analysis of magnetic fields and childhood leukaemia, Br J Cancer 83(5):692-8
[4] California report, (2002) a 560 page report. An Evaluation of the Possible Risks From Electric and Magnetic Fields (EMFs) From Power Lines, Internal Wiring, Electrical Occupations and Appliances.
The report (with good Refs) is available at An excellent summary and commentary on the report by Professor Denis Henshaw of Bristol University is available at his website (This link opens in a new window) at Bristol University.
[5] Draper G et al, (2005) Childhood cancer in relation to distance from high voltage power lines in England and Wales: a case-control study British Medical Journal 1290-1293
[6] Lowenthal RM et al, (2007) Residential exposure to electric power transmission lines and risk of lymphoproliferative and myeloproliferative disorders: a case-control study Internal Medicine Journal 37(9):615-619
[7] Marcilio I et al, (2011) Adult mortality from leukemia, brain cancer, amyotrophic lateral sclerosis and magnetic fields from power lines: a case-control study in Brazil Rev Bras Epidemiol 14(4):580-8
[8] Baldi I et al, (2011) Occupational and residential exposure to electromagnetic fields and risk of brain tumors in adults: a case-control study in Gironde, France Int J Cancer 129(6):1477-84
[9] Tenorio BM et al, (2012) Evaluation of testicular degeneration induced by low-frequency electromagnetic fields J Appl Toxicol 32(3):210-8
[10] Li DK et al, (2002) A population-based prospective cohort study of personal exposure to magnetic fields during pregnancy and the risk of miscarriage Epidemiology 13(1):9-20
[11] Li DK et al, (2010) Exposure to magnetic fields and the risk of poor sperm quality Reprod Toxicol 29(1):86-92
[12] Auger N et al, (2012) Stillbirth and residential proximity to extremely low frequency power transmission lines: a retrospective cohort study Occup Environ Med 69(2):147-9
[13] Qiu C et al, (2004) Occupational exposure to electromagnetic fields and risk of Alzheimer's disease Epidemiology 15(6):687-94
[14] Davanipour Z et al, (2007) A case-control study of occupational magnetic field exposure and Alzheimer's disease: results from the California Alzheimer's Disease Diagnosis and Treatment Centers BMC Neurol 7:13
[15] Davanipour Z & E Sobel (2009) Long-term exposure to magnetic fields and the risks of Alzheimer's disease and breast cancer: Further biological research Pathophysiology 16(2-3):149-56
[16] García AM et al, (2008) Occupational exposure to extremely low frequency electric and magnetic fields and Alzheimer disease: a meta-analysis Int J Epidemiol 37(2):329-40
[17] Navarro EA et al, (2003) The microwave syndrome: a preliminary study in Spain Electromagnetic Biology and Medicine 22 (2 & 3): 161-69
[18] Oberfeld G et al, (2004) The Microwave Syndrome: Further Aspects of a Spanish Study International Conference Proceedings, Kos, Greece
[19] Hutter H P et al, (2006) Subjective symptoms, sleeping problems, and cognitive performance in subjects living near mobile phone base stations Occup Environ Med 63: 307-313
[20] Abdel-Rassoul G et al, (2007) Neurobehavioural effects found among inhabitants around mobile phone base stations Neurotoxicology 28(2):434-40
[21] Bortkiewicz A et al, (2004) Subjective symptoms reported by people living in the vicinity of cellular phone base stations: review Med Pr 55(4):345-51
[22] Eger H et al, (2004) The influence of being physically near to a cell phone transmission mast on the incidence of Cancer Umwelt Medizin Gesellschaft 17.4.2004
[23] Wolf R & Wolf D (2004) Increased incidence of cancer near a cell-phone transmitter station Int J of Cancer Prevention 1(2)
[24] Balmori A (2009) Electromagnetic pollution from phone masts. Effects on wildlife Pathophysiology 16(2-3):191-9

[Return to top]

Are phones with low SARs safer?

SARs are one way of measuring the amount of radiation emitted by a mobile phone. The higher the SAR, the greater the amount of microwaves that are likely to be absorbed by the head. New phones in the UK are forced by law to display maximum SAR levels in the manual that comes with the phone. Unfortunately, most phones and their accompanying manuals come in blister packs, so you will not have sight of the manual before purchase, unless you ask to see a copy of the appropriate manual that shopkeepers have assured us they will have available for customers to see.

Using SARs for comparison, German scientists from the Institute for Satellite and Mobile Communication, reported that some models of mobile phones expose users to up to 20 times more radiation than others on the market. They produced a list of 25 models of phones together with their SARs, which became out of date almost immediately because phone manufacturers bring out new models and old ones become redundant at a quicker rate than the list can be updated and accurate. We do not believe that lists of SARs are a useful guide to the layman, anyway, as SARs are based only on thermal effects, which is not what most concerned scientists are worried about.

The SAR values quoted for mobile phones assume that a mobile phone is transmitting at its maximum possible power for a period of 6 minutes. Depending on the location of the tissue, and the thermal conductivity of neighbouring tissue and local blood flow, 'maximum SAR' figures can vary over at least a 10-fold range. Dr Michael Kundi (from the University of Vienna) said that the mechanisms involved in keeping the temperature at an acceptable level for proper biological functioning could become exhausted, or the strain induced in the system might have some adverse effects in the long run.

There are considerable variations of efficiency of any given handset. In response to low signal strength, an efficient handset powers up less than an inefficient handset, thus exposing the head to lower radiation. Some phones with a high peak SAR actually produce lower SARs under normal use conditions than phones with a low peak SAR, sometimes with a power reduction factor of up to 1000 or even several million-fold with 3G/UMTS handsets.

The power level that a mobile phone operates at during a call depends on the quality of the radio link to the base station. If the link is good (lots of bars), a low output power level will be used, whereas if the link is poor (few bars), a higher output level will be used.

[Return to top]

Are cordless home phones dangerous?

There has been quite a lot of publicity about the research showing that using digital cordless (DECT) phones results in similar adverse health effects as using a mobile phone, including the risk of developing brain tumours [1,2,3,4]. This research seems to be scientifically sound and the evidence for problems is growing.

It seems that because of their convenience, people, such as teenagers wanting privacy from parental ears, talk for long periods of time on cordless phones. Unfortunately, it may have unforeseen consequences that neither they nor their parents could have anticipated.

There is a more detailed free article on DECT phones in the EMFields library.

We do not discuss particular models of DECT phones, as these are changed too rapidly for us to be able to assess them.


[1] Hardell L et al, (2006) Pooled analysis of two case-control studies on the use of cellular and cordless telephones and the risk of benign brain tumours diagnosed during 1997-2003, International Journal of Oncology 28:509-519
[2] Hardell L et al, (2006) Pooled analysis of two case-control studies on the use of cellular and cordless telephones and the risk for malignant brain tumours diagnosed during 1997-2003, International Archives of Occupational and Environmental Health 79(8):630-9;
[3] Hardell L & M Carlberg 2009 - Mobile phones, cordless phones and the risk for brain tumours Int J Oncol 35(1):5-17
[4] Mild KH et al 2007 - Pooled analysis of two Swedish case-control studies on the use of mobile and cordless telephones and the risk of brain tumours diagnosed during 1997-2003 Int J Occup Saf Ergon 13(1):63-71

[Return to top]

What is the best way to wire a house to reduce electromagnetic fields in the home?

The current UK practice of wiring a house using 'ring' circuits can often lead to high electric and magnetic fields. In Europe 'radial' or 'tree and branch' wiring is more common than in the UK and these result in much lower levels of EMFs in buildings. In addition, running wires in metal conduit will reduce the fields to virtually zero. For new build homes this is the best option. There are different types of screened cable available when running wires in metal conduits is not possible.

Mineral insulated cables can be expensive to install, some are fire retardant and are likely to need extra residual current devices or RCDs. There are difficulties with some braided cables which need earthing at every junction point, and some need extra space to allow for the necessary larger bending requirement.

Most cables, including reasonably priced, flexible cable can be bought from an electrical goods supplier, such as used by professional electricians. Very competent DIYers can also re-wire houses, but it is important to remember that it is now illegal for unqualified people to undertake major electrical work without formal independent third-party inspection and test.

"House wiring and EMFs", which can be found in the free article library, has detailed information about the different types of circuit, cable specifications and what type to use in which situation, for the use of the competent DIYer, or professional electrician. In the UK only competent people can make wiring changes and the house wiring will require Part P inspection, testing and certification before you can sell the house.

[Return to top]

Why does my Acoustimeter have problems picking up WiFi/wLan in some places?

A WiFi/wLAN receiver is tuned to be extra sensitive at WiFi frequencies so that it can detect the signals over a considerable distance.

Typically 5 millivolts per metre (0.005 V/m or c. -79 dBm/m2) will give an indication of a "full strength signal" and the system will be able to work at full speed (11 Mbs upwards depending on the technical Standard and frequency band being used).

1 mV/m (0.001 V/m or -86 dBm/m2) will give a good performance.
0.1 mV/m (0.0001 V/m or -96 dBm/m2) will enable most laptops WiFi links to work at 1 Mbps speed.
0.05 mV/m (0.00005 V/m or -99 dBm/m2) may allow a sensitive WiFi unit to just about connect.

WiFi/wLAN Access Points are generally 200 mW or 500 mW. 200 mW generates about 2 V/m at 1 metre, 0.2 V/m at 10 metres, 0.02 V/m at 50 metres clear line of sight (no obstacles). In buildings these fall to more commonly 0.05-0.1 V/m at 10 metres, 0.02 V/m at 5 metres distance.

Longer ranges can be achieved by using a good external antenna with better gain. + 15 dB can easily be achieved.

The receivers in mobile phones have similar sensitivities though some can pick up SMS messages at -102 dBm/m2.

The Acoustimeter should record a WiFi/ wLAN working in a laptop when it connects. Typically this would read several volts per metre peak about 50 cm from the screen. It is possible that some laptops have adaptive power control and the wLAN access point is actually fairly close, in which case the signals from the laptop will be much lower even when transmitting.

The Acoustimeter is a broad-band measurements device for assessing human exposure. Its lowest reading is at 0.02 V/m (20 millivolts per metre) peak signal strength.

We know of no scientific or medical reports showing that levels below 0.05 V/m affect people, though there may be people with extreme sensitivity who might react to levels below this; fortunately such sensitivity is uncommon.

[Return to top]

I don't want a WiFi connection to broadband internet - what options do I have?

To connect to the internet, you need one of two things: either a cable connection (via a company such as NTL) or a standard phone line. With old-fashioned dial-up internet the computer communications will use the normal voice line and you will not be able to use the telephone at the same time, unless you have two lines (and separate numbers) for the telephone and for the dial-up modem.

However, modern internet connections normally use a technology called ADSL (Asymmetrical Digital Subscriber Line). This technology needs to be enabled at your local telephone exchange, but almost 100% of the UK (as of Summer 2011) is now supported. Lowest is in rural Scotland where it falls to only 98%. Many areas now have super-fast SDSL (Synchronous Digital Subscriber Line). Contact your phone provider (for example BT) and ask them if they can provide broadband to your house - if so they are also likely to be able to send a package containing all you need to connect your computer to the internet (modem, ADSL filter and cables). The modem enables the computer to connect, and the filter ensures that you can use the telephone at the same time as the internet (with only one line) without having either service compromised. We do not recommend wireless (WiFi) modems and recommend non-wireless Routers (rather than modems) as they provide a "firmware firewall" which makes it very difficult to hack into your computer and steal your personal information.

Both cable and ADSL.SDSL internet connections are entirely free of microwave EMF emissions, and we have no reason to believe they could be a risk to health.

It is very important however, if you are concerned about health effects from wireless communication devices, not to use one of the "BT Home hubs" to connect your computer to the internet, as they act as both a wireless access point (WiFi) and a DECT base unit (cordless phones) whenever they are powered. For an alternative, ask in your local computer store for a non-wireless "router" - there are a number of brands that manufacture these, and they are very secure, reliable and require very little setting up.

[Return to top]

I have more than one computer and want them all to be able to use the internet - do I have to use WiFi?

No, not at all. If you have purchased a router for your internet connection (see FAQ above), then you will have a number of network "ports". These are the sockets at the back of the router that you plug the network cable from your computer into. You can have as many computers as you have ports provided you have a cable for each. The router will make sure that the machines can all share the internet at the same time. If you need more connections, then you need to purchase a multi-way Ethernet "switch" which can provide many more connection sockets. They are not expensive.

[Return to top]

Follow EMFields on Facebook       About Us       Warranty contact       Terms and Conditions       Cookies Policy       Privacy Policy
Follow EMFields on Facebook       About      Warranties      Terms      Cookies      Privacy
Follow EMFields on Facebook       About    Warranties    Terms    Privacy