Electromagnetic wave pollution

Define electromagnetic wave pollution, also known as electromagnetic pollution or radio frequency radiation pollution. Characterized by the force of electromagnetic field, it is closely related to the nature, power, density and frequency of electromagnetic wave. Due to the wide application of electronic technology, the rapid development and popularization of radio broadcasting, mobile phone, television and microwave technology, the power of RF equipment has doubled and the electromagnetic radiation on the ground has greatly increased. It has reached a level that can directly threaten human health. Electromagnetic pollution is an invisible pollution, which has become a public hazard of great concern. The impact on human society has attracted the attention of all countries in the world and is listed as one of the environmental protection projects.

classify

Man-made electromagnetic wave pollution includes:

① Pulse discharge. For example, when a high-current circuit is cut off, spark discharge has a large transient current, which will produce strong electromagnetism. It is essentially the same as lightning, but the affected area is smaller.

② Power frequency alternating electromagnetic field. For example, the electromagnetic fields near high-power motors, transformers and transmission lines do not radiate outward in the form of electromagnetic waves, but will cause serious electromagnetic interference in the near field.

③ Radio frequency electromagnetic radiation. Such as radio broadcasting, television and microwave communication. , wide frequency range, large influence area, which can cause harm to near-field staff. Radio frequency electromagnetic radiation has become the main factor of environmental electromagnetic wave pollution.

mode of transmission

1 radio and television transmitting equipment, mainly used for radio broadcasting and communication, is the transmitting station and turntable of radio and television in various places.

The communication between communication radar and navigation transmitting equipment includes short-wave transmitting station, microwave communication station, ground satellite communication station and mobile communication station.

High frequency equipment for industry, scientific research and medical treatment. This kind of equipment converts electric energy into heat energy or other energy for utilization, but it leaks out with electromagnetic radiation, causing environmental pollution in the workplace.

Industrial electromagnetic radiation equipment: mainly high-frequency induction heating equipment, such as high-frequency quenching, high-frequency welding and high frequency furnace, high-frequency melting equipment and high-frequency medium heating equipment, such as plastic packaging machine, high-frequency drying processor and high-frequency medium heating linkage machine.

Medical electromagnetic radiation equipment: mainly short wave and ultrashort wave physiotherapy equipment, such as high frequency physiotherapy machine, ultrashort wave physiotherapy machine, ultraviolet physiotherapy machine, etc.

Scientific research on electromagnetic radiation equipment: mainly electron accelerators, various ultrasonic devices, induction cookers, etc.

Electromagnetic radiation interference of traffic systems, including electrified railways, light rail and electrified railways, trams and trolleybuses.

Trams, etc.

Electromagnetic radiation of power system, high voltage transmission lines include overhead transmission lines and underground cables, and substations include power plants and substations.

Electromagnetic radiation of household appliances, including microwave heating and transmitting equipment, including computers, monitors, televisions, microwave ovens, wireless phones, etc.

Electromagnetic wave pollution in family life is closely related to people's daily life, which refers to the interference, influence and harm of electromagnetic waves with different wavelengths and frequencies generated by various electronic life products, including air conditioners, computers, televisions, refrigerators, microwave ovens, karaoke machines, VCD players, stereos, electric blankets, mobile phones, etc. In normal work.

Main danger

Because electromagnetic waves are colorless, odorless, invisible and traceless, pollution is both unconscious and ubiquitous, which is called "electronic waste" or "electronic radiation pollution" by scientists. The harm it brings to people cannot be underestimated. Mainly in the following three aspects:

(1) affects the normal operation of electronic equipment.

Modern science and technology are increasingly inclined to use large-scale and ultra-large-scale integrated circuits. The density of circuit elements is extremely high, and the current used is micro-current, which makes the signal power almost the same as the noise power. Parasitic radiation may cause misoperation or obstacles of electronic systems or electronic equipment. On the other hand, with the rapid development of modern wireless communication industry, various transmission towers make air waves crowded, which seriously affects all aspects of normal business. Since1September, 1996, the aviation communication frequencies above 1.30 MHz in Beijing Capital Airport have been frequently interfered by wireless paging stations. 1996 at 8: 00 am on February 20th, the air-to-air passage was seriously disturbed, and 10 plane had to hover in the air, resulting in the departure plane having to fly for 5 ~ 15 minutes. Similar incidents occur frequently in other parts of the country. In places where people are used to thinking that the sky is high and birds fly, the interference of electromagnetic waves has brought great harm to people.

(2) Scientific research and facts show that electromagnetic waves are also very harmful to human body.

The harm of electromagnetic radiation to human body is caused by the energy of electromagnetic waves. According to experts, the mobile phone used in China.

The emission frequency of voice is between 800 ~ 1000 MHz, and its radiation dose can reach 600 microwatts, which is more than 0/0 times of the national standard/kloc-0. Excessive electromagnetic radiation can cause neurasthenia, loss of appetite, palpitation, chest tightness, dizziness and other "electromagnetic wave allergy", and even lead to brain tumors. There are many examples of the harm of electromagnetic wave pollution to human body, but the degree of its influence is related to the radiation intensity and the length of accumulation time, and it has not been widely reflected at present, so it has not attracted people's general attention. Relevant research shows that the pathogenic effect of electromagnetic wave increases with the increase of magnetic field vibration frequency, and the frequency exceeds 65438+ 100000Hz, which may pose a potential threat to human body. Working and living in this environment for too long, the human body is disturbed by electromagnetic waves, which changes the original electric field of molecules in the body tissue and leads to the disorder of the ecological balance of the body. Some people exposed to strong electromagnetic radiation or long-term electromagnetic radiation will have pathological manifestations, mainly in the nervous system and cardiovascular system. Such as fatigue, memory loss, insomnia, irritability, menstrual disorder, chest tightness, palpitation, leukopenia and thrombocytopenia, and decreased immune function.

(3) Danger of explosion or explosion of explosive mixture.

Some tall metal structures will generate spark discharge due to high frequency induction under certain conditions. This kind of discharge not only gives people different degrees of electric shock, but also may detonate dangerous goods, causing disastrous consequences. This is a problem that explosive manufacturers need to attach great importance to.

(4) Electromagnetic radiation is one of the main causes of cardiovascular diseases, diabetes and cancer mutation.

(5) Electromagnetic radiation will directly harm human reproductive system, nervous system and immune system.

(6) Electromagnetic radiation is one of the inducing factors of abortion, infertility and teratogenesis in pregnant women.

(7) Excessive electromagnetic radiation directly affects the development of children's body tissues and bones, leading to the decline of vision and liver hematopoietic function, and in severe cases, it can lead to retinal detachment.

(8) Electromagnetic radiation can make male sexual function decline and female endocrine disorder.

Pollution pathway

There are two ways to interfere with the propagation of electromagnetic waves:

One is conducted interference, which is the interference caused by the current propagating along the power line;

The other is radiation interference, which is caused by the emission of electromagnetic waves into the surrounding space.

In order to prevent and suppress electromagnetic interference, reasonable circuit design, filtering, shielding and other technical methods are mainly adopted. Reasonable circuit design is to arrange components and circuits reasonably in a narrow space, which can weaken parasitic electromagnetic coupling and suppress electromagnetic interference. A filter is a circuit composed of resistors, inductors and capacitors. This network can allow signals of some frequencies to pass, while preventing signals of other frequencies from passing. The correct design and installation of the filter can minimize electromagnetic interference. As a basic means to suppress electromagnetic radiation, shielding technology has been widely used. Purpose of shielding

Whether to limit radiation energy to a specific area or to prevent radiation energy from entering another specific area. Shielding material is the key to shielding efficiency. The newly developed absorbing materials have come out, which will contribute to the development of clean space for human beings. In addition to the above technical methods, other methods can be used to reduce the harm of electromagnetic radiation pollution, such as prohibiting the establishment of high-power wireless paging stations around the airport and taking good shielding and protective measures for staff who often contact RF equipment.

In a word, with the development of science and production, the harm of electromagnetic radiation pollution tends to increase, so it is of great practical significance to study the harm and protection of electromagnetic wave pollution.

Penetration of electromagnetic waves

Because electromagnetic wave has wave-particle duality, the wavelength is inversely proportional to photon energy. The shorter the wavelength, the greater the photon energy and the stronger the penetration. For example, high-energy X-rays can penetrate almost all nonmetals, even thin aluminum; Although gamma rays can penetrate most metals. Some heavy metals, such as lead, can block the penetration of electromagnetic waves.

Related case

More than 20 years ago, after the popularization of household microwave ovens in the United States, some patients with pacemakers often felt uncomfortable, and some pacemakers could not even stop. Later, scientists' research revealed the truth to the world because of "electromagnetic wave pollution".

A few years ago, Nikolai Kedkov, a famous Russian chess master, played a game of chess with his computer. After winning three games in a row, I was suddenly knocked down by the powerful current released by the computer. According to the investigation, it was not a computer hardware leak, nor was it a software design killing program. The cause of death was invisible electromagnetic waves.

It is reported that workers who work in front of the computer for more than 6 hours every day are prone to a disease called "VOT". This disease refers to the general term for the pathological changes in some parts of the body caused by watching video terminals for a long time. Its main symptoms are: visual dysfunction; Neck, shoulder and wrist dysfunction; Vegetative nerve dysfunction, etc. ; In addition, it can also cause gynecological diseases such as irregular menstruation and abortion and other skin diseases. The reason is also caused by electromagnetic radiation.

Mobile phones and walkie-talkies are also sources of high-frequency electromagnetic waves, which emit electromagnetic waves every time you talk. Scientists believe that the electromagnetic radiation intensity of mobile phones generally exceeds the prescribed standard by 4-6 times, and some types even exceed nearly 100 times. After two years' follow-up testing by China Electromagnetic Radiation Testing Center and Xiamen Changqingyuan Radiation Protection Institute, it is confirmed that the mobile phones currently used in China will cause radiation damage to human body.

prevention and control of pollution

There are many easy-to-operate measures to reduce the harm of electromagnetic wave pollution.

There are two general principles:

First, due to work needs, shielding and protective measures need to be taken;

Second, try to increase the distance between the human body and the emission source.

Because the influence of electromagnetic waves on human body is closely related to the emission power and the distance from the emission source, its harmful process

Degree is directly proportional to transmission power and inversely proportional to the square of distance. Take the mobile phone as an example. Although its transmitting power is only a few watts, because its transmitting antenna is very close to people's heads, the actual radiation intensity is equivalent to a broadcasting station of several hundred kilowatts dozens of meters away. Fortunately, people will not show obvious harmful symptoms for a short time; However, after a long time of use, the symptoms caused by radiation will gradually be exposed, and excessive radiation will cause abnormal cell activity and division, which may cause cancer.

In view of this, we should consciously take measures to reduce the harm of electromagnetic wave pollution in daily life. For example, people who work in places with high electromagnetic wave intensity, such as computer rooms, should pay special attention to rest during their work, and can appropriately go outdoors far away from electromagnetic fields for activities; When using a mobile phone, try to keep the antenna away from the human body, especially the head, and try to reduce the time of each call; Household appliances should not be placed centrally, and the distance from watching TV should be kept at 4 ~ 5 meters. Pay attention to window ventilation; Microwave ovens and refrigerators should not be used nearby; Teenagers should play video games as little as possible; After the electric blanket is preheated, the power supply should be cut off when sleeping, and children and pregnant women should not use the electric blanket; Usually, you should eat more fresh vegetables and fruits to enhance your body's ability to resist electromagnetic wave pollution.

First, keep your distance. The distance from the TV should be the screen size multiplied by 6, the distance from the microwave oven is 2.5 ~ 3 meters, and the distance from the high-voltage transmission line is generally regarded as a safe area.

Second, reduce contact. People who often use computers should rest every hour of work 15 minutes, and work for no more than one week.

32 hours later.

Third, improve the environment. Pay attention to air circulation, moderate temperature and humidity, and it is best not to put household appliances in the bedroom.

Fourth, personal protection. Pregnant women, children, the infirm, people who are allergic to electromagnetic radiation, and people who have been in an environment where electromagnetic wave pollution exceeds the standard for a long time should choose to use protective equipment that suits them.

Fifth, use mobile phones less. Minimize the use of mobile phones, walkie-talkies and cordless phones, and make a long story short when using them; Don't hang your mobile phone on your body often.

Sixth, use less electric blankets. The electromagnetic wave pollution of electric blanket is serious, which is harmful to human body after long-term use. When it is needed in cold weather, it is suggested to cut off the power supply immediately after heating the bed to reduce electromagnetic wave pollution.

Seven, the use of shielding to reduce electromagnetic wave pollution. For facilities that produce electromagnetic pollution, shielding materials that shield, reflect or absorb electromagnetic waves, such as copper, aluminum, steel plate, polymer film, etc. , you can use.

Eight, according to the characteristics of electromagnetic wave attenuation with distance, in order to reduce the harm of electromagnetic waves to residents, workplaces and facilities that emit large electromagnetic power and may produce strong electromagnetic waves, such as TV stations, radio stations, radar communication stations, microwave transmitting stations, etc. , should be located as far away from residential areas in suburban counties or higher-lying areas. Substations and other facilities that must be set in cities, adjacent residential areas and places where residents often move should keep a certain safety protection distance from residential areas to ensure that their boundaries meet the requirements of environmental electromagnetic wave health standards. At the same time, the electromagnetic radiation source should be shielded by metal wires or polymer films such as copper, aluminum and steel, which can shield, reflect or absorb electromagnetic waves, so as to limit the electromagnetic radiation energy in a specified space.

Nine, high voltage transmission lines, especially EHV transmission lines, should be far away from residential areas, schools, sports fields and other crowded areas. When using a computer, you should choose a low-radiation display screen, and keep the distance between the human body and the front of the display screen not less than 75cm, and the side and back not less than 90cm. It is best to install shielding devices.

Ten, should strictly control the density of mobile communication base stations, to ensure that all kinds of mobile communication base station antennas set in urban areas are higher than the surrounding buildings, kindergartens, school buildings, hospitals and other buildings around a certain range shall not set up transmitting antennas.

Eleven, in order to reduce the electromagnetic pollution in the home and its harmful effects, we should always ventilate the room and keep the indoor air unblocked. Scientific use of household appliances: for example, watching TV or home theater, when listening to the stereo, keep a long distance and avoid turning on all kinds of appliances at the same time; The duration of using computers or video games should not be too long.

Twelve, when using a mobile phone, try to reduce the talk time; The top of the mobile phone antenna deviates from the head as far as possible, and the antenna is as long as possible; Add headphones to the mobile phone.

Thirteen, in addition, you can take a certain amount of vitamin C every day or eat more fresh vegetables rich in vitamin C, such as pepper, persimmon pepper, Toona sinensis, cauliflower, spinach and so on. Eat more fresh fruits such as citrus and jujube. Pay attention to eat foods rich in vitamins A, C and protein, such as tomatoes, lean meat, animal livers and bean sprouts. Drink green tea often. These dietary measures can play a positive role in preventing and reducing the harm caused by electromagnetic radiation to human body to a certain extent.

14. electromagnetic radiation is a new kind of environmental pollution that people have only realized in recent thirty or forty years. Now people are still in the stage of understanding and studying electromagnetic radiation. Because we can't see, touch or feel, it is easy to arouse people's suspicion. In addition, some reports about electromagnetic radiation are not objective and scientific, which leads to unnecessary misunderstanding and panic. Generally speaking, to judge whether electromagnetic radiation pollutes the living environment, we should comprehensively consider the intensity of electromagnetic radiation, the main radiation direction, the distance from the radiation source, the duration and other factors. Therefore, while strengthening electromagnetic protection, we should also adopt a scientific attitude, objectively analyze and take it seriously, and we should not blindly exaggerate what others say, which makes people confused. Of course, with the development of science and technology, people's understanding of electromagnetic wave pollution and its harm will gradually deepen, and many mysteries will eventually be revealed. Electromagnetic environment standards and related laws and regulations. In order to control the environmental pollution caused by electromagnetic waves in modern life and protect people's health, the Ministry of Health of China promulgated the Hygienic Standard for Environmental Electromagnetic Waves (GB9 175-88-88) on February 22nd1989, stipulating that the electromagnetic wave intensity in residential areas should be less than lOV/m and the ultrashort wave should be less than 5V/m.

In view of the development of mobile communication, Beijing Environmental Protection Bureau promulgated the first "Regulations on Environmental Protection Management of Beijing Mobile Communication Construction Project" (for Trial Implementation) in February, 2000 17, in order to standardize the construction and operation of mobile communication stations and prevent them from causing electromagnetic pollution to the environment. It is clear that mobile communication stations (stations) that can generate electromagnetic radiation should go through the formalities of environmental protection examination and approval before construction, and should go through the examination and approval of environmental protection acceptance. After monitoring by the environmental protection department, the local power density meets the national standard that the frequency is within the range of 20 MHz~3000 MHz and the power density of the radiation outlet limit is 40μW/cm2, before it can be officially put into use. If it exceeds this standard, it must be stopped or rectified. Before building cellular mobile communication base stations, it is necessary to predict the user density distribution, adopt the best frequency reuse mode, and minimize the number of base stations; To build a mobile communication station (station) on a residential building, the building property right unit or the property management unit must obtain the opinions of the residents in advance; The minimum allowable height of wireless paging communication and trunking communication antenna shall not be less than 40m, and the outdoor antenna of cellular mobile communication base station shall generally not be less than 25m. Generally, it is not allowed to build hospitals, kindergartens, schools, houses and other buildings higher than the antenna within 50m of the main shooting direction and 30m of the non-main shooting direction of the transmitting antenna. The construction unit shall set up electromagnetic radiation warning signs at the above antenna installation site.