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Typical exposure levels at home and in the environment
13/12/2012
Background electromagnetic field levels from electricity transmission and distribution facilitiesElectricity is transmitted over long distances via high voltage power lines. Transformers reduce these high voltages for local distribution to homes and businesses. Electricity transmission and distribution facilities and residential wiring and appliances account for the background level of power frequency electric and magnetic fields in the home. In homes not located near power lines this background field may be up to about 0.2 μT. Directly beneath power lines the fields are much stronger. Magnetic flux densities at ground level can range up to several μT. Electric field levels underneath power lines can be as high as 10 kV/m. However, the fields (both electric and magnetic) drop off with distance from the lines. At 50 m to 100 m distance the fields are normally at levels that are found in areas away from high voltage power lines. In addition, house walls substantially reduce the electric field levels from those found at similar locations outside the house.  Electric appliances in the household The strongest power frequency electric fields that are ordinarily encountered in the environment exist beneath high voltage transmission lines. In contrast, the strongest magnetic fields at power frequency are normally found very close to motors and other electrical appliances, as well as in specialized equipment such as magnetic resonance scanners used for medical imaging. Typical electric field strengths measured near household appliances (at a distance of 30 cm) (From: Federal Office for Radiation Safety, Germany 1999) <td bgcolor="#ffffff" height="3
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