电磁场

All of us depend on electricity to meet basic needs such as heating, cooling and lighting our homes. We also depend on electricity to meet the transportation, 沟通, 商业, 休闲, industrial and health care requirements of our society. 无论我们在哪里用电, power frequency electric and/or magnetic 字段 (EMF) are present.

电场


磁场示意图

Electric 字段 are created around appliances and wires wherever a 电压存在. You can think of electric voltage as the pressure of water in a garden hose – the more voltage, the higher the electric field 强度. Electric 字段 are present when an electrical appliance is 即使关机也能插上电源. Electric 字段 diminish rapidly with distance from the source and can be shielded by objects such as 树木或建筑物的墙壁.

磁场


磁场示意图

Magnetic 字段 are created whenever there is a flow of electric current. This can be thought of as the flow of water in a garden hose. As the amount of current flowing increases, so does the magnetic field. Magnetic 字段 are present when there is a flow of electricity, such as when an electrical appliance is operating. Magnetic 字段 are measured in milligauss (mG), and diminish rapidly with distance from the source, but are not shielded by objects such as trees or buildings. The level of magnetic 字段 from electrical appliances in homes can be as high as or higher than the magnetic 字段 people may experience under power lines. Magnetic field 强度 from power lines depend on many factors, 包括线路的设计, the amount of current the line carries, 以及到直线的距离.

Median EMF readings in milligauss (mG)
 
Earth's magnetic field (direct current)*
波250 - 650 mG

Video display terminals (VSTs) (distance 1')*
波5 mG

电范围(距离1')
波8 mG

洗碗机(距离1')
波10 mG

复印机(距离1')
波20 mG

真空吸尘器(距离1')
波60 mG

电动剃须刀(距离6英寸)
波100 mG

吹风机(距离6英寸)
波300 mG

1 NIEHS, EMF Questions and Answers, 2002年6月

Magnetic 字段 decrease as distance from 电力来源增加

Magnetic 字段 decrease as distance from 电力来源增加
 

*levels shown above are examples only, not predictions of actual EMF from PSE lines
Source: 国家 Institute of Environmental Health Sciences (NIEHS), EMF Questions and Answers. 2002年6月.

电动势研究

For over 40 years, there have been many scientific studies conducted on power frequency EMF. Extensive reviews and research conducted by leading public health agencies – such as the World Health Organization (WHO) and the U.S. 国家 Cancer Institute (NCI) (one of the U.S. 国家 Institutes of Health) – have not established that power frequency EMF cause any adverse effects in 人或动物.


世卫组织认为

Based on a recent in-depth review of the scientific literature, the WHO concluded that "current evidence does not confirm the existence of any health consequences from exposure to low level electromagnetic 字段."2

2世卫组织EMF规划网站: www.谁.int/news-room/q-a-detail/radiation-electromagnetic-字段

Similarly, the 美国国家癌症研究所 has concluded that, “Numerous epidemiologic studies and comprehensive reviews of the scientific literature have evaluated possible associations between exposure to non-ionizing EMFs and risk of 癌症 in children. 没有一致的证据证明 association between any source of non-ionizing EMF and 癌症 has been found.”

NCI Fact Sheet "Electromagnetic Fields and Cancer" - www.癌症.gov/about-癌症/causes-prevention/ risk/radiation/electromagnetic-字段-fact-sheet

暴露极限

美国也没有.S. government nor the state of Washington has established exposure standards for public 暴露在工频电磁场下. Two international organizations, the International Commission on Non-Ionizing Radiation Protection (ICNIRP) and the Institute of Electrical and Electronic Engineers International Committee on Electromagnetic 安全 (ICES), have developed exposure guidelines that 得到了世卫组织的认可.

既定的电磁场暴露限值
 
International Commission on Non-Ionizing Radiation Protection
2,000 mG

IEEE International Committee on Electromagnetic 安全
9,040 mG

Exceedance of these safety standards requires that a person be exposed to EMF levels higher than those listed above for any duration of time. There are no time restrictions for exposures below the threshold.

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