Albert _ Jiao? Published in? 20 13-0 1- 18

Myth:? Try not to take the high-speed train Recently, high-speed rail flight attendants recruited another batch, because the last batch resigned collectively. Because the high-speed rail radiation is serious, the flight attendants are either infertile or aborted, because only the high-speed rail movement is introduced, and there are no carriages and radiation protection equipment at all! Because a half-meter piece of radiation-proof glass costs 30 thousand yuan, they save their own pockets, but the people will suffer greatly! If you don't believe me, someone has measured the change of electromagnetic radiation on the high-speed rail. Obviously, when accelerating, especially when running at high speed, the electromagnetic radiation is very large, sometimes even exceeding the electromagnetic radiation of microwave ovens.

Truth:

How big is the high-speed rail radiation?

In fact, not only high-speed rail, but also many electric-driven vehicles such as electric locomotives, electric diesel locomotives, subways and trams will produce electromagnetic radiation. The electromagnetic radiation in the train compartment is not only related to the electrical characteristics of the train, but also related to the complex factors such as the vehicle type, the position and height of the measuring points in the train compartment, the running state of the train and so on. In the following discussion, we will focus on the electromagnetic radiation in the passenger compartment of the high-speed train.

High-speed rail is short for high-speed railway. Trains running on China's high-speed railways generally use 25,000 volts and 50Hz alternating current. Accordingly, the high-voltage power equipment of high-speed rail will radiate the electric field and magnetic field in this frequency band.

1, electromagnetic field radiation limit with frequency of 50Hz.

According to ICNIRP's safety standards? [ 1]? ICNIRP is the international commission on non-ionizing radiation protection. This is a non-governmental independent organization composed of experts in many fields. According to the latest scientific research progress, the organization evaluates the potential harm of various non-ionizing radiation to human health. The radiation safety standard proposed by ICNIRP has been adopted by dozens of countries and international organizations. The relevant standards of China State Environmental Protection Administration also refer to ICNIRP standard? [2]? ), the "extremely low frequency electromagnetic radiation" of about 50Hz generated by high-speed rail, the safety standard of electric field radiation is below 5kV/m (kV/m is kilovolts per meter, the unit of electric field intensity), and the magnetic field radiation is 100? t(？ T is micro-Tesla, the unit of magnetic induction intensity) below. This safety standard is based on international medical research, and there is not enough scientific evidence to show that this standard needs to be adjusted.

The electromagnetic field safety reference level set by ICNIRP for the public [1]. 50Hz electromagnetic field should refer to the fourth line, where the electric field limit is 250/f and the frequency f=0.05kHz, so the limit is 5000 V/m; The limit value of magnetic field is 5/f, and the limit value is 100? t .)

2. Measured magnetic field radiation of high-speed trains at home and abroad.

There are different types of trains running on the high-speed rail. The first is centralization. The main electrical equipment and traction motor of this kind of train are concentrated on the locomotives at one or both ends of the train, which are separated from the passenger compartment. The other is distributed power, and the power system is distributed in multiple vehicles. Studying in the UK 1998? [3]? The results show that the electromagnetic radiation of power concentrated trains is mainly concentrated near the engine room and cab. The radiation value of the magnetic field in the passenger compartment is generally 30? Below t, the height of passengers sitting, the typical radiation value is less than 5? T. Power distributed trains, especially early models, can detect relatively large magnetic field radiation near the reactor at the height of the car floor; However, the radiation received by passengers is still within the safe range.

What's the situation in China? Searching for Chinese periodicals, no literature reports about magnetic field radiation in the crew cabin were found. But there was a video circulating on the Internet, in which someone used an instrument to measure the magnetic field radiation value near the train window, and the measured value was about 10? Unfortunately, the video only measures the magnetic field radiation near the window, and does not explain what kind of high-speed train it is on. Moreover, the video is not from official media reports and can only be used as a reference. But only from the video, the measured magnetic field intensity value is within the limit specified by ICNIRP (100? Within t).

3. Measurement of electric field radiation of China EMU.

A Chinese paper on 20 12? [4]? The electric field radiation in the EMU is measured, and it is found that the electric field radiation value is distributed in the range of 0.011-0.021kv/m in the first-class carriage, second-class carriage, sewing and driver's cab. This value is also within the limit (5kV/m) specified by ICNIRP.

4. Radiation in other frequency bands

In addition to the above 50Hz power frequency radiation, high-speed rail will also produce radiation in other frequency bands. There are many reasons for this situation, such as the radiation caused by poor contact between pantograph and catenary, and the radiation caused by related components in the process of current transformation and frequency conversion. This radiation has a wide frequency range, ranging from tens of Hz to 2GHz. Is there a corresponding research and national standard for this kind of radiation? [5]? The measurement method and data processing method are specified.

20 10 there is a paper in China? [6]? This kind of radiation in the train compartment of EMU is measured and analyzed, and the radiation in 30 MHz～200 MHz frequency band is studied emphatically. According to the actual measurement, the electric field intensity radiated in this frequency band is only 50dB? V/m or so, less than 1mV/m (millivolts per meter). The safety standard set by ICNIRP for electric field radiation in this frequency band is 28V/m? [ 1]? The electromagnetic radiation protection standard formulated by China's Environmental Protection Bureau has no clear restrictions, but the reference value 12V/m is given. [7]? . No matter which value is taken, the measured value in the above study is still far from the safety standard. This kind of radiation generally only considers the interference to electronic equipment, and its influence on human body can be ignored.

High-speed rail radiation and microwave oven radiation

The rumor that "(high-speed rail electromagnetic radiation) exceeds microwave oven electromagnetic radiation" is easily misunderstood. First of all, the comparison with the electromagnetic radiation of high-speed rail here obviously cannot refer to the microwave radiation generated inside the microwave oven to heat food. The two frequencies are different and cannot be directly compared. What's more, the microwave radiation of the microwave oven is confined in the metal furnace, which will not cause harm to the outside creatures. If it is to be compared, it should be compared with the low-frequency radiation emitted by microwave ovens (and other household appliances). The following is the size of the magnetic field radiation value of some electrical appliances in the home at a distance of 30 cm? [8]? , can be used as a reference:

Microwave oven: 4-8? T

Fluorescent lamp: 0.5–2? T

Washing machine: 0.15–3? T

Refrigerator: 0.01–0.25? T

Television: 0.04–2? T

Computer: less than 0.0 1? T

As mentioned above, some studies have measured that the magnetic field radiation value in the compartment is 30? Below t, generally 5? T. It can be seen that the radiation of high-speed rail cars is still higher than some common household appliances, but only slightly higher, within the safe range (100? T) inside. Also, considering that our time on the train is usually only a few hours, there is no need to worry too much.

For the electromagnetic radiation of household appliances, please refer to this article: Is the hair dryer a killer of high radiation? 》)

Does 30,000 pieces of radiation-proof glass exist?

The rumor also mentioned that there is a kind of "radiation-proof glass, which costs 30 thousand yuan for half a meter." However, after searching online, I didn't find out where the glass with the cut cake price was sold.

Radiation protection glass generally refers to the glass used in hospital X-ray room or nuclear power plant, mixed with a small amount of lead. It can absorb and block X-ray radiation and nuclear radiation. [9]? . This kind of glass can prevent ionizing radiation (radiation that can destroy molecules and cause harm to living things, including X-rays and nuclear radiation), and? Does low-frequency electromagnetic radiation belong to non-ionizing radiation? It has nothing to do with the function of this protective glass. Some radiation-proof glass refers to the glass used in some buildings to absorb and block thermal radiation and make rooms warm in winter and cool in summer? [ 10]? . None of this radiation refers to the low-frequency electromagnetic radiation on the high-speed rail.

Even if this kind of glass used to protect low-frequency electromagnetic radiation really exists, it will not be of much use to high-speed rail radiation. As mentioned above, the electromagnetic radiation in the car mainly comes from the traction motor at the bottom of the power car. Unless this "radiation-proof glass" is laid on the floor, it has little to do with the radiation in the carriage. In fact, the metal shell of the carriage itself has a certain shielding effect on electromagnetic radiation. The train designer will make the metal plate at the bottom of the car thicker to block the radiation of the traction motor.

High-speed rail radiation makes flight attendants infertile?

The above talked about the impact of high-speed rail radiation on the general population. Then, for flight attendants who have been working on high-speed rail for a long time, will high-speed rail radiation make them "infertile" or "aborted"?

First, let's look at animal experiments. According to the report of the World Health Organization? [ 1 1]? Scientists have done a lot of research on the influence of extremely low frequency electromagnetic radiation on biological reproductive system in the past. For example, in the laboratory, pregnant mice are exposed to extremely low frequency electromagnetic radiation with different intensities for several days to observe whether the mice have abortion, infertility and fetal malformation. Most of the results show that not only under the radiation intensity level of high-speed rail cars (several? T to dozens? T), even if the radiation intensity reaches tens of thousands in some experiments? T is many times the radiation of high-speed rail, and mice can also give birth to mice healthily. There is no evidence that extremely low frequency electromagnetic radiation can cause biological infertility or abortion.

In addition to experiments on mice, the researchers also investigated whether there are significant differences in pregnancy rate and abortion rate among people who receive different electromagnetic radiation in daily life, including people with different occupations and living habits (such as whether they often use electric blankets that can generate extremely low-frequency electromagnetic radiation). [ 1 1]? . The research results are different, and most of them have not found that the proportion of infertility and abortion of women who receive relatively more electromagnetic radiation has increased significantly; The most serious is "the risk is slightly higher than that of ordinary people", such as research? [ 12]? It is considered that the risk of premature birth is twice as high as that of normal cases when women receive extremely low frequency electromagnetic radiation with a maximum of 3.5 1 μT 24 hours a day. However, this kind of investigation also has some defects. For example, some studies have found that the abortion rate of women working near electrical equipment is slightly higher, but it cannot be ruled out that it is due to radiation or other reasons such as work fatigue and noise. Based on these research results, the horror of "flight attendants are either infertile or abort and resign collectively" is purely alarmist and will not happen.

For the influence of electromagnetic radiation on pregnant women, please refer to this article: Do pregnant women need to wear radiation protection suits? 》)

Conclusion:? As an electric-driven vehicle, high-speed rail does produce radiation, but the radiation value in the carriage is only larger than that of household appliances at home, which meets the international electromagnetic radiation safety standards. There is no evidence to prove that it poses a threat to human health. Radiation-proof glass protects against ionizing radiation and has nothing to do with high-iron electromagnetic radiation. The relationship between extremely low frequency electromagnetic radiation produced by high-speed rail and female infertility rate and abortion rate has not been clearly confirmed in the study.

References:

[ 1] ( 1,? 2)? Guidelines for exposure of electric, magnetic and electromagnetic fields (below 300GHz) under ICNIRP limits

[2] Technical Specification for Environmental Impact Assessment of HJ Electromagnetic Radiation /T 24- 1998 500 kV EHV Power Transmission and Transformation Project.

[3] The magnetic field on the British train. Chadwick P, Lowes F. National Radiation Protection Committee, chilton, Didcot, Oxon, UK,

[4] Distribution characteristics of power frequency electric field intensity in the train compartment; Zhai Yibiao, Huo Wei, Liu Qiaoying, Baoshan Chen, Zhang Jinlong, Shi Lei; Journal of Environment and Health; September 20 12 Volume 29, Issue 9

[5] GB/T15708-1995 Measurement Method of Radio Radiation Interference Caused by Electric Locomotive Operation in AC Electrified Railway.

[6] Study on the conversion relationship between off-line noise radiation field strength of pantograph and catenary of electric locomotive inside and outside the vehicle; Zhang Qiang

[7] GB 8702- 1988 electromagnetic radiation protection regulations

8 World Health Organization: Electromagnetic fields.

[9] Research progress of radiation protection materials; Xiong Jun, Song Tao; China tissue engineering research and clinical rehabilitation; Volume 14 12

Gong Jianhua, Zhang Zhejun

[ 1 1] ( 1,? 2)? World Health Organization: Environmental Hygienic Standard for Extremely Low Frequency Electromagnetic Radiation Chapter 10: Reproduction and Development

[12] Nested case-control study on magnetic field measurement and abortion in residence and individuals. General manager Li, neutron RR, Hristova L, yost m, Hiatt ra. Epidemiology 2002 1 month; 13( 1):2 1-3 1.

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Can I be hurt by electromagnetic radiation by taking the high-speed rail?

He explained that at present, the public's troubles about train radiation are mainly concentrated on maglev trains. The operation principle of wheel-rail high-speed train is different from that of maglev train. The electromagnetic field generated by its power transmitter is mainly power frequency electromagnetic field, which is actually electromagnetic radiation. It comes from the magnet of power transmission and transformation system and motor. This kind of electromagnetic radiation itself is very harmful to human body, and has little influence compared with ionizing radiation, microwave and other radiation. Moreover, this kind of radiation has a feature that it will be shielded by metal and cannot penetrate metal materials. All train bodies are made of metal, which is a basically closed metal box, so less electromagnetic radiation enters. For electromagnetic radiation, the state also has a set of strict indicators to monitor. The railway department systematically monitors the carriages and cabs of high-speed trains all the year round, and its electric field and magnetic field intensity meet the relevant national standards and will not affect the health of passengers.