electromagnetic environment
Since 1998, the World Health Organization (WHO) has published official opinions on the impact of electromagnetic sources with different frequencies on public health in the form of fact sheets of the international electromagnetic field research program, and expounded the mechanism and safety limits of the impact of exposure to electromagnetic sources with different frequencies on human health.
The influence of electromagnetic environment on biological system depends on the wavelength (frequency) and energy of electromagnetic source. The higher the frequency, the greater the energy and the greater the impact on the human body.
"Ion radiation" is a kind of electromagnetic wave (X-ray and γ-ray) with extremely high frequency, and its photon energy is enough to break the chemical bond of DNA in cell genetic material molecules, that is, ionization occurs.
"Non-ionic radiation" refers to the part of the electromagnetic spectrum with low frequency and energy, which means that the photon energy in this frequency band is too weak to break the chemical bond between cells and molecules. They include ultraviolet (UV) radiation and visible light waves, infrared waves, radio frequencies and microwaves, as well as extremely low frequencies and electrostatic and magnetic fields. No matter how high the intensity of "non-ionic radiation" is, it cannot cause ionization in biological systems.
Power transmission and transformation facilities will produce power frequency electric field, magnetic field, wireless signal interference and some noise, which mainly cause people to panic. When the electrical equipment is connected to the power supply (that is, "voltage" is added), its conductor carries low-frequency alternating charge, and a low-frequency electric field is formed between the conductor and the earth. The power frequency used in power transmission and transformation projects in China is 50 Hz. In the field of electric power or electric power, the frequency of 50 Hz is usually called "power frequency", which belongs to extremely low frequency electric field.
In the surrounding environment of transmission lines or power facilities, electric fields and magnetic fields exist independently, unlike high-frequency electromagnetic fields which form effective electromagnetic energy radiation or energy absorption in the body in the form of electromagnetic waves. Therefore, in the field of extremely low frequency environmental health impact, international authoritative organizations only involve the analysis of electric field and magnetic field, without using the vague concept of "electromagnetic radiation", and no international authoritative organization will misuse the term "electromagnetic radiation" in this field.
In fact, China's environmental protection standards for power transmission and transformation electromagnetic fields are stricter than international standards. The exposure limit of power frequency electric field intensity is 5 kV/m, and the exposure limit of power frequency magnetic field intensity is 0. 1 mTesla, which is promulgated by an international authoritative organization recommended by WHO to protect public health. The limits of public protection in China are 4 kV/m electric field and 0. 1 mTesla magnetic field, which are often lower than these standards in actual construction.
In fact, electromagnetic fields are everywhere in our lives. It is estimated that when we enjoy the beautiful moonlight and turn on the TV at home, the intensity of electromagnetic field around us is much higher than that of transmission lines. The earth itself has a geomagnetic field. Comparing the geomagnetic field existing on the earth with the magnetic field generated by power transmission and transformation facilities, we can also draw an interesting conclusion: the geomagnetic field data observed in Beijing is 54 micro-Tesla, and the maximum intensity when the magnetic field reverses is about 100 micro-Tesla, which is 50 ~ 100 times of the electromagnetic field of power transmission and transformation facilities. This shows that people can hardly feel anything when they live in the electromagnetic field of tens of micro-Tesla, even the staff who are on duty 24 hours a day in the substation will not be affected. There is a transformer in the west of my house.
It is about 20 meters away from my home. It is used by more than 70 families. Will it cause radiation damage to your family?
Answer 20 meters away, there will be no radiation hazard, 4 kV/m× 20 m = 80,000 volts, so the transformer voltage is 80,000 volts?