EMF's refers to the Electro-Magnetic Fields that are produced by electrical circuits and equipment.

At low levels they are deemed to be harmless but at higher levels they have many detrimental health implications.

The term EMF refers to both Electric and Magnetic fields:

• Electric fields are present whenever electricity is present. - e.g. There will be electric fields around cables to a bedside light even when the light is switched off but the cable is still "live". Electric fields also occur naturally - for example, if you wear insulating shoes, on a dry day a charge will accumulate on your body  - sometimes you can see this discharge by touching a conductive object where there may be a little spark!
• Magnetic fields are only produced when electricity is being used: e.g In the above example when the light is off there will be no magnetic fields produced from the cable, but with the light on, and electricity flowing, there will be some magnetic fields produced. With correctly wired "low power" circuits these magnetic fields should be very low and generally not a problem. With high power circuits or electrical power supplies, these fields can become very strong and should be avoided. These fields rapidly reduce with distance so you can avoid them by keeping away.  For example we often have chargers and power supplies plugged in under our desk, then we rest our feet on them !!! - this is easy to fix just move them 1/2m away. Metal boxed devices such as PCs are generally pretty good and don't emit many magnetic fields, but the plastic cased devices such as transformers and power supplies are made very cheaply and dont have any shielding so are much worse. 

The practical solution to check your home is to either hire a specialist to come and survey your house for you, or buy an EMF meter to check it yourself. This way you can eradicate many of the basic problem devices, possibly replacing them with better made, more modern devices that don’t produce such horrendous fields. There are many potential EMF hotspot causes that you will be able to isolate and fix yourself, but sometimes you will need an electrician to fix any house wiring problems and bring it up to a good standard.

Every home in the western world will be awash with many different radio, TV and phone signals - again at a low level perfectly harmless, but not so good when the levels are too high.

How much EMF is safe?

After more than 25 years of intensive study, the health and safety conscious Swedish government has established a safety limit for exposure to ELF magnetic field at 2.5 mG, and VLF magnetic fields at only 0.25 mG. The Swedish standard is generally accepted throughout the world.

What this possibly means is that if someone consistently experiences exposure, which exceeds the standard, that person could be at risk for developing health problems.

Even though the controversy of conflicting scientific studies persists, it seems strange that cigarettes and alcohol are packaged with warnings we already know about, and the sodium, fat, and cholesterol content of foods must appear on the labels, but no one tells you that the average hairdryer, vacuum, or electric can opener can emit an amazing 300mG or more!

Choosing a EMF Meter.

The three main types of fields ate electric, magnetic and radio - each of these requires a very different meter for it to be measured. But you can buy meters that combine all three functions into a single device.

Where to start.

The most important areas for your health are those locations in your house where you spend the most time. Start with the bedrooms - first make sure the beds are clear of any significant fields. Turn on all the electrical devices in the room and then move the meter over the bed. If you detect and significant EMF then switch off the electrical devices and scan the bed again. If the EMF has gone then you can switch on your devices one by one to determine which one is causing the problem. If the EMF persists with everything switched off then you need to investigate further - move the scanner around and find where the EMF is highest - does this location coincide with any potential wiring, plumbing or other metalwork?

Mains powered bedside electric clocks have a very poor record for producing high levels of EMF - maybe its time to get a new one but check it out first in the shop!