There are many sources of electromagnetic radiation, generally speaking, there are natural electromagnetic radiation and artificial electromagnetic radiation.
Natural electromagnetic radiation is spontaneous in nature, such as lightning, sunspot activity, earthquake, volcanic eruption and so on. Natural electromagnetic radiation has existed since the birth of the earth, and human beings have adapted to this natural electromagnetic radiation in the long process of evolution. Under normal circumstances, natural electromagnetic radiation is within a certain safety threshold, and human beings have certain adaptability.
Artificial electromagnetic radiation is mainly produced in the process of human production activities. After entering the electrification era, due to the needs of production and life, a large number of electrical appliances have been manufactured, and the electromagnetic radiation in the environment has mainly changed into artificial radiation. In today's society, radar systems, TV and broadcast transmission systems, RF induction and medium heating equipment, RF and microwave medical equipment, various electrical processing equipment, communication transmitting stations, satellite earth communication stations, large power stations, power transmission and transformation equipment, office automation equipment, high-voltage transmission lines, subway trains, electric trains, microwave ovens, radios, televisions, mobile phones, computers, WIFI routers, etc. can all generate electromagnetic radiation in different forms, frequencies and intensities.
Electromagnetic radiation is different from the transformation of other energy forms. It is an invisible and intangible magnetic field. Since electromagnetic radiation is a kind of energy transmission, its energy should be large and small. According to quantum theory, electromagnetic radiation consists of photoelectrons, and its energy depends on frequency. Generally speaking, the greater the frequency, the smaller the wavelength and the greater the intensity of electromagnetic radiation; The smaller the frequency, the greater the wavelength and the smaller the electromagnetic intensity.
Electromagnetic waves are divided into long wave, medium wave, short wave, ultrashort wave and microwave according to frequency. Generally speaking, long wave has a weak influence on human body. The shorter the wavelength, the higher the frequency, and the greater the influence on human body, especially microwave.
When the intensity of electromagnetic radiation exceeds the limit that human body or environment can bear, it will cause electromagnetic radiation pollution.
Electromagnetic radiation pollution refers to the fact that the intensity of electromagnetic radiation exceeds the background value and maximum allowable limit of biological or electrical equipment, which affects biological health and the normal work of electrical equipment.
Electromagnetic radiation pollution is closely related to the characteristics, power, density and frequency of electromagnetic waves.
Natural electromagnetic radiation pollution has little influence, because it is natural selection and eventually achieves a harmonious relationship, while artificial electromagnetic radiation pollution has a great influence on the environment. People often say that electromagnetic radiation pollution mainly refers to artificial electromagnetic radiation, which will cause discomfort to living things and affect the normal use of electrical equipment. It is a kind of electromagnetic radiation that needs special prevention.
For decades, domestic and foreign media have been reporting the harmful effects of electromagnetic radiation.
A research report from three Nordic countries, such as Sweden, shows that the chances of suffering from leukemia, brain tumor and other diseases are 2. 1 times and 1.5 times higher than those of normal people, respectively.
According to a survey report of the World Health Organization, electromagnetic radiation is one of the main causes of cardiovascular diseases, diabetes and canceration, which can directly harm human reproductive system, nervous system and immune system, reduce male sexual function, and cause female endocrine disorders and menstrual disorders. Long-term exposure to high electromagnetic radiation will change blood, lymph and cell protoplasm, affect human circulatory system, immunity, hormone secretion, reproduction and metabolism, and even induce cancer, diabetes and hereditary diseases. Exposure of patients with pacemakers to high electromagnetic radiation will affect the normal use of pacemakers. More seriously, high-intensity electromagnetic radiation also has a considerable degree of adverse effects on the fetus.
Electromagnetic radiation mainly affects organisms through thermal effect, non-thermal effect and cumulative effect;
heat effect
More than 70% of the human body is water, and water molecules rub against each other after receiving electromagnetic radiation, causing the body to heat up. Thermal effect means that electromagnetic waves emitted by electromagnetic radiation "heat" tissues in living organisms through the surface layer. Because there is no response to this "fever" effect in the body and there is no corresponding heat dissipation mechanism, the tissues in the body are damaged, which will seriously affect the normal function of the body. This effect is mainly influenced by high-frequency electromagnetic radiation, which acts on the body. When the radiation is not serious, it is not easy to see from the outside of the body, but when the radiation is serious, it can be seen from the inside of the body that the body has been seriously damaged.
(2) Non-thermal effect
There are weak electromagnetic fields in human organs and tissues, which are stable and orderly. Once disturbed by the external electromagnetic field, the weak electromagnetic field in the equilibrium state will be disordered. After repeated electromagnetic radiation, the functions of central nervous system, immune system, endocrine system and reproductive system have changed. The common diseases that may be caused are infant malformation, tumor, leukemia and so on. Non-thermal effects are mainly influenced by low-frequency electromagnetic radiation, which can be generally divided into physical non-thermal effects and chemical non-thermal effects, among which chemical non-thermal effects are extremely harmful to organisms.
(3) Cumulative effect
After thermal effect and non-thermal effect act on human body, if it is radiated by electromagnetic waves again, the damage to human body will continue to accumulate, and it will become a permanent lesion after a long time before it can repair itself.
It should be noted that experts and scholars at home and abroad have been studying the biological effects of electromagnetic radiation for half a century. However, due to the different research objectives, methods and conditions (different distances, time, biological models, etc.). ), the research results and opinions are not consistent, and sometimes even completely opposite.
The band of electromagnetic radiation we usually say refers to the electromagnetic wave from ultra-long wave to microwave, and it is also the main band that mainstream appliances can emit.
Generally speaking, electromagnetic waves with high intensity and small wave band have the greatest influence on human body, but a premise must be added, that is, the time length of electromagnetic wave irradiation.
If electromagnetic waves are compared to water, then the intensity can be compared to the flow velocity of water, and the band can be compared to the flow velocity. The time length is universal, so it is easy to understand. When we observe the influence of water flow on the dam, it must be that the water flow with large flow, high velocity and long time has a greater influence on the dam, and it is one-sided to talk about impact failure without any factors.
Therefore, when we talk about the influence of electromagnetic radiation on human body, we must comprehensively consider the intensity, wavelength and duration.
Here I want to make it clear first, that is, I personally prefer that the electromagnetic radiation emitted by electrical appliances has an impact on the human body!
Because, in the information I have contacted, almost all articles that say that electromagnetic radiation of household appliances is harmless have theoretical basis; If it is harmful, you can cite experimental or research basis.
In the United States, Sweden, Britain and other countries, the safe value of power frequency electromagnetic radiation is also set at a very low value (0.2 or 0.4 micro Tesla), and it is clearly required that children's activities must be lower than this value. This value is 100 micro Tesla in our country. I don't have the ability to prove that this value is unsafe, but I don't think anyone wants to work and live next to such high electromagnetic radiation equipment.
Most electrical appliances in our life emit power frequency electromagnetic radiation. Many people say that this kind of electromagnetic radiation has no effect on human body, but it is not. In this place, we must be clear about its intensity and duration. A certain intensity of power frequency electromagnetic radiation can still roast chicken steak, and low intensity electromagnetic radiation exposed for many years will also bring certain changes to the human body. The former is similar to a sea roar, while the latter is similar to a dripping stone.
Of course, we can't touch the electromagnetic radiation of roast chicken. Usually, the electromagnetic radiation we can touch is not more than 50 micro Tesla (μT). We don't feel anything under this electromagnetic radiation. But there will be household appliances or office equipment that we have been in contact with for a long time, such as electric blankets, computers, televisions, refrigerators, fish tank oxygen pumps and so on. Fortunately, this kind of electrical appliance is not very close to us, only mobile phones, computers and electric blankets are relatively close.
Many countries prohibit the construction of residential buildings and public places near high-voltage lines, otherwise the prices of houses built in these places will be very low. Personally, I have measured that the electromagnetic radiation value at a place around 10KV 30 meters is between 0.07 and 0.09 micro Tesla. Even according to the standards of Sweden and the United States, this is a safe range, but these countries still make such regulations, which shows that they do not feel that the electromagnetic radiation safety value they set is not necessarily safe.
Some cities in our country once wanted to make their own electromagnetic radiation safety standards. For example, Beijing once wanted to set this standard at 1 micro Tesla, but some scholars immediately opposed it and rejected this proposal. In the end, this proposal was not passed, and it is not known whether it involves the game of economic interests of all parties.
My advice to you is to stay away from high electromagnetic radiation equipment as far as possible. If close contact is necessary, try to shorten the contact time as much as possible.
Electromagnetic radiation is invisible, intangible and intangible, and its harm is slow and hidden. The harm of electromagnetic radiation to people varies from person to person. Some people have no influence in the strong radiation field, some people may have a great influence, and some diseases may take a long time to appear.
Therefore, protective measures should be taken for the elderly, children, pregnant women or patients with pacemakers, people who are sensitive to electromagnetic radiation, and people who work in an environment with excessive electromagnetic radiation for a long time.
The following are some common methods to prevent electromagnetic radiation:
1, don't put household appliances too concentrated to avoid being exposed to excessive radiation. Especially some household appliances that are easy to generate electromagnetic waves, such as radios, televisions, computers, refrigerators, etc. , not suitable for centralized display in the bedroom.
2. Try to avoid staying in the direct area of the transmitting antenna for a long time.
3. Various household appliances, office equipment, mobile phones, etc. Try to avoid using it for a long time, and try to avoid using a variety of office equipment and household appliances at the same time.
4, when using electrical appliances, the human body and electrical appliances should keep a safe distance. The farther away from the electrical appliance, the less electromagnetic wave will harm. For example, the distance between people and color TV sets should be 3 to 4 meters, the distance between people and fluorescent tubes should be 2 to 3 meters, and the distance between people and microwave ovens should be at least 1 meter. The electromagnetic radiation released at the moment when the mobile phone is turned on is the largest. When using, the distance between the head and the antenna of the mobile phone should be as far as possible, and it is best to use a separate earphone and microphone to answer the phone. Electric blankets are the most harmful to pregnant women, children and the elderly, so use them with caution.
5. Conditional units and individuals can be equipped with radiation protection clothing, radiation protection screen, radiation protection curtain, radiation protection glass and other radiation protection devices. To block electromagnetic radiation from the body to the maximum extent.
With the development of electromagnetic technology, human life has undergone profound changes. Electromagnetic technology not only brings convenience to life, but also brings threats. How to make good use of electromagnetic technology and prevent electromagnetic radiation pollution is becoming more and more important. The state should constantly improve the relevant standards of electromagnetic radiation, strengthen supervision, and relevant units should also attach importance to electromagnetic radiation, strengthen publicity and education, so that people can understand the basic principles of electromagnetic radiation, master relevant protection knowledge, and avoid electromagnetic radiation damage.
Electromagnetic radiation will cause discomfort or even serious harm to human body, but it does not mean that as long as there is electromagnetic radiation, it must be a catastrophe.
At the beginning of the article, we said that in today's society, each of us lives in electromagnetic radiation. As a physical phenomenon, electromagnetic radiation has always existed in nature. From the perspective of human function, only excessive radiation will do harm to the body. The necessary knowledge of "radiation protection" in daily life is essential, but there is no need to be afraid of electromagnetic radiation.
The word radiation sounds dangerous, but the true meaning of radiation has been greatly misinterpreted and exaggerated. It actually just means "spreading around", so electromagnetic waves are called electromagnetic radiation because they are "radiated" by charged particles. In the electromagnetic spectrum, according to the wavelength from long to short, it can be divided into radio waves, microwaves, infrared rays, visible light (red, orange, yellow, green, indigo and purple), ultraviolet rays, X-rays and gamma rays.
Different electromagnetic waves have different radiation patterns, and most of the electromagnetic waves we come into contact with in our daily life are not strong in radiation intensity.
The vast majority of radiation does not actually harm the human body, so don't worry. What really causes cancer is a special kind of radiation called "ionizing radiation".
According to the energy level, radiation can be divided into ionizing radiation and non-ionizing radiation. Ionizing radiation energy is high, which can directly destroy DNA and cause gene mutation, so there is a risk of cancer, while non-ionizing radiation energy is low enough to destroy DNA, so there is no risk of cancer in theory.
The energy of non-ionizing radiation is not high, which can not directly affect cells and DNA, and theoretically will not cause cancer. And scientists have actually done a lot of research, and the conclusions are very clear. Exposure to these radiations will not increase the possibility of cancer.
20 1 1 year, the international agency for research on cancer listed electromagnetic radiation (cell phone signal) as "possible carcinogen", which caused many people to panic. There is an article on the internet that long-term use of mobile phones may lead to brain tumors.
What is the truth?
Don't panic.
First of all, "possible carcinogen" does not mean carcinogen. In fact, the exact meaning is "some people say that it may cause cancer, but it can't be proved yet, which deserves continued attention."
The "Possible Carcinogens" of the International Agency for Research on Cancer covers everything, even coffee.
Why did the mobile phone fall into the pit of "possible carcinogen"?
Mainly because of a Swedish study: 10 years or more, the probability of this person getting glioma (a subspecies of brain tumor) is slightly higher than that of people who don't use mobile phones (from 0.005% to 0.0 16%).
In fact, there are many controversies about this research in the scientific community, mainly because its experimental design is not rigorous. For example, its data source is not an objective record, but depends on everyone filling out a form to report. But the question is, in the past 10 years, can you really remember exactly the time you used your mobile phone every day?
Although many scientists don't buy it, the data is there after all. To be on the safe side, the International Agency for Research on Cancer dubbed the mobile phone "a possible carcinogen", which means: "If you believe it, you will believe it; if you don't believe it, you will have nothing. Let's wait until there is more data in the future. "
Later, the World Health Organization and the International Committee on Non-ionizing Radiation Protection made in-depth research. Except for heat, there is no evidence that non-ionizing radiation has substantial harm to human health. Symptoms such as neurasthenia are mostly psychological effects. Long-term animal experiments have also proved that putting animals in an environment where electromagnetic radiation is higher than that around the communication base station has not found any effect on them.
Of course, science is not complete. We just stand on the current level of understanding and come to the conclusion that non-ionizing radiation has no other influence except fever. Other potential hazards may be found in the future, but at least, there is no scientific basis, including theoretical basis and practical basis.
The debate about whether electromagnetic radiation is harmful to people has never stopped. It is credible that strong radiation is harmful to people, so electromagnetic radiation of general intensity should also affect people's health. However, the scientific community has been inconclusive about the strength of the standard that affects health. In order to nip in the bud, the international community has taken this standard as a mandatory standard.
China's electromagnetic radiation safety standard is 8 MW/cm2, and all electrical appliances sold in the market need to meet this standard, so there is no need to worry too much about radiation. So what is the electromagnetic radiation intensity of our common household appliances? It should be noted that the radiation intensity of different specifications and brands of the same electrical appliance is different, and the same level of radiation causes different injuries to different people. Usually, pregnant women and fetuses are fragile and the most vulnerable, so electromagnetic radiation should be avoided.
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