Personal computers are used in daily activities by millions of people all around the world. Computerization in the country assumes breadth, and many thousands of people spend most of their working hours and free time in front of the screens. Along with the recognition of the undoubted benefits of computer technology usage, one can find out that it causes anxiousness in PC users influencing their health. Cell phones, microwave ovens, computers and TVs have the most significant effect on the human body. In particular, microwaves have impact mainly for a short period of time (on average from 1 to 7 minutes). Television is significantly harmful only in case of a short distance between it and the audience. The influence of mobile phones on the human body is a separate topic and can be discussed in hours.
However, the sources of electromagnetic radiation, with which a person interacts for a long time, often are the most dangerous. In this context, the problem of electromagnetic radiation of PC, in other words, the impact of computers on the human body throw into sharp relief due to several reasons:
• The computer has two sources of electromagnetic radiation (the monitor and the system unit);
• PC user often is deprived of the opportunity to work at a safe distance;
• Long-time effect of the computer (for advanced users it may be more than 12 hours, with official regulations prohibiting work on the computer for more than 6 hours per day).
In addition, there are several secondary factors that aggravate the situation; they include work in close unventilated room and the concentration of multiple PCs in one place.
Computer Screens and Their Influence. PC monitors made of the electron tubes are potential sources of soft X-ray, ultraviolet, infrared, visible, radio-frequency and ultra-low-frequency electromagnetic radiation (Barett). It was found that the levels of electromagnetic fields in the user’s zone frequently exceed the biologically dangerous level. One should not forget that the radiation of a laptop or PC affects not only the user, but also people who are close to him/her. In addition, not only a person who is sitting at a computer but the one sitting/standing right in front of the user (at an angle). Consequently, the distance plays a role. The latest researches showed that the distance up to 1.5 m should be considered as dangerous for the human health. It should be noted that the electromagnetic radiation of each computer item increases the overall electromagnetic background of the room.
1. Electromagnetic waves over the permissible values;
2. Negative informational component (Torsion fields);
It was established experimentally that the electromagnetic radiation has a torsion component (Reed). It was trashed out that exactly torsion fields rather than electromagnetic are a major factor in the negative impact on human health, in view of the fact that it is the torsion field that transmit all that negative information that could cause headaches, irritability, insomnia, etc. to people.
3. Psychotropic effects (in particular, with regard to use of the Internet).
Monitor, especially its side and back parts, are a very powerful source of radiation (Barett). Despite annual appearance of severe regulations that are to limit the power of the radiation monitor are enacted, it leads only to the application of coating on the front of the screen, which is said to protect the user better, while the side and back panels, as additional powerful sources of radiation, stay unprotected. The main sources of electromagnetic radiation of the monitor (video display terminal) are the electron tube, spinners, pulse power supply and vision amplifier.
It is considered that the screens used in laptops, being based on liquid crystals, do not generate a whole “bouquet” of harmful electromagnetic radiation of the conventional monitors with electron tube (Barett). It is known that electromagnetic radiation of the laptop computers far exceeds the environmental standards. The laptop is usually located closer to the user, and, therefore, the radiation sources are more likely to affect the field of vital human organs, especially because some laptop users tend to place their computers on their knees or belly. Electron tube is not the only source of emission of electromagnetic fields. The field can be generated by a voltage converter power supply, control and generating information circuits on digital LCD screens and other items of equipment.
The increased electromagnetic field ensures the computer impact on people’s health (Sandström 137). As a result of the continuous work at a computer, the person feels tired, he/she becomes extremely irritable and anxious, often answering the questions with unambiguous answers, becomes unattending and careless. In modern society, such phenomenon has been called chronic fatigue syndrome and according to the official medicine it has no cure yet.
• 60 % of users – the eye diseases;
• 60 % of users – diseases of the cardiovascular system;
• 40 % of users – diseases of the gastrointestinal tract;
• 10% of users – skin diseases;
• various tumors.
Electromagnetic radiation of the computer is especially dangerous for children and pregnant women (Hartmann). Children’s bodies in comparison to the adult have some unique features, for example, a larger ratio of the length of the head to the body, higher conductivity of the brain substance and so on. Due to the smaller size of the child’s head its specific absorption rate is more than the one of adults, and the radiation penetrates deeper into those regions of the brain, which in adults, as a rule, are not irradiated. The water and ion content decreases with the head and skull thickening; thus, conductivity decreases as well. It is proved that growing and developing tissues are most susceptible to the adverse effects of electromagnetic fields, and strong human growth takes place from the moment of impregnation until about 16 years.
As for pregnant women, the EMF is biologically active regarding embryos. The embryo sensitivity to damaging factors is much higher than the sensitivity of the parent organism. It was found that intrauterine fetal damage by EMF can occur at any stage of its development: during fertilization, cleavage, implantation, and organogenesis. However, the periods of maximum sensitivity to EMF are the early stages of embryo development that are implantation and early organogenesis.
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Among the hazards faced by the people working at the monitor, there are X-rays and electromagnetic radiation, electrostatic field (Barett). Due to the strict standards that exist nowadays, doses of X-rays from modern video monitors are not dangerous for most users. The exception is people with hypersensitivity to it (X-ray radiation from the monitor is dangerous to pregnant women because it can have adverse effects on the fetus in the early stages of development as it was mentioned earlier). Experts did not come to a definite and the only accurate conclusion about the impact of electromagnetic radiation on the human body, but it is clear that radiation levels recorded near the monitor are not dangerous.
When the monitor is on there exists an electrostatic field. Its tension levels are low and insignificantly affect the human body as opposed to the higher levels of the electrostatic field, being typical of the industrial applications. More consequential to users is the ability of the charged microparticles to adsorb the dust particles that prevents their settling. Aspiration of this dust cocktail means exposing oneself to additional risk of allergic diseases of the skin, eyes and upper respiratory tract.
The electron tube of the computer screen emits a soft X-ray radiation, which is called inhibitory. It is caused by inhibition of the electron beam. It is obviously not removable; however, it is possible to lower it by various absorbent layers transparent to visible rays. By the way, the speed-up voltage in monochrome monitors is three times fewer than in color ones since they have only one electron gun, so they are much safer from this point of view. Some time ago, manufacturers struggled with radiation by installing removable protective filters for X-rays and at the same time increasing the contrast of the image. Then the glass of the monitor display became layered, and the term low radiation emerged. The similar meaning has less common term ‘low emission’. It should be noted that, at present, all electron tubes are produced with relatively safe level of X-ray radiation (Sandström 139).
Numerous coils inside the monitor, i.e. coils of line and frame scanning, power transformers and correction coils, generate an alternating electromagnetic radiation of low frequency field, which can adversely affect the health of the user (Sandström 140). It extends substantially to the sides and back as screen weakens the radiation. Therefore, there are certain rules for the organization of position: the monitor of the neighbor should be sufficiently distant. Reduction of low-frequency radiation is a complex engineering task; it can be solved through careful screening and special additional coils inside the monitor. Expression of low radiation can be applied to the manufacturer’s attempts to reduce this component of the monitor radiation.
High voltage used in electron tubes leads to the electrostatic field outside the monitor creation, which by its nature is similar to the produced by the TV kinescopes. In case the monitor does not have special technical solutions for protection (such as filters), providing the weakening of the external field, the potential of the accumulated charge reaches 10-30 kV (Sandström 140). One can feel it, raising a hand to his/her pocket. The presence of static electricity leads to the same cracking as while stroking a cat. The human body can be charged up to a voltage of a few kilovolts. The level of the charge depends on the clothes material, coating material of the chair, the fibers the carpet is made of, relative humidity in the room and a number of other factors. Under the influence of an electrostatic field the charged particles, depending on their sign (positive or negative) are attracted or repelled by the screen, wherein the particles with a positive charge may get to the user. The special anti-static coating is applied to the screen in order to remove the electrostatic charge. Formerly, the protective shields were used.
Computer monitors are X-ray, beta – and gamma- radiation sources. The X-ray radiation is present and emitted only when the monitor is on. It occurs when the electron beam is decelerated and as the characteristic radiation of atoms tube materials. X-ray spectrum is continuous with the set of monoenergetic lines. As opposed to X-ray emission, beta- and gamma-rays are present when the monitor is on or off. The source of this radiation is a radioactive decay of nuclei of the uranium, thorium, and potassium -40 nuclei. The spectral composition of gamma radiation preferably comprises a set of monoenergetic lines. Beta – radiation monitor is mainly determined by radioactive decay of potassium -40 nuclei the spectral content of beta radiation is continuous. Under certain conditions, this ionizing radiation is able to cause harm to human health, in particular, clouding of the eye lens. To reduce the harmful effects of ionizing radiation the anode voltage was reduced, and the lead was added in the glass of monitors. Whether the ionizing radiation emitted by computer monitors is dangerous or not depends on the levels of ionizing radiation entering the eyes of computer users.
Monitor Interferes Eyes. Whether the person’s eyes will get tired of the computer depends not only on its technical parameters, but also on how the display of the monitor is close to natural colors. This can be applied to everything; for example to the color of the objects, backgrounds, fonts, sharpness, contrast nature, and even the color of the computer casing.
Doctors say that computer vision syndrome (CVS) occurs in 40-92% of those working at the computer every day, and in 10-40% of those who use them from time to time (Sweeney). Ophthalmologists often hear complaints about the sense of heaviness, burning, “sand” in the eyes, pain during eye movement, redness, tearing and photophobia.
Continuous operation even at modern flat screen hurts people’s eyes (Hartmann). After all, any screen has discrete image; it is presented by luminous points. The display flickers; it has low contrast and uneven brightness. It does not respond to the type of image to which the body of a person has adapted through evolution. As a result, reading of the text on the computer screen is a big stress for the eyes, and it is stronger than usual stress that results from reading a common book or newspaper.
Great significance according to the doctors has the resolution of the monitor; the distinguishability of the picture, as well as brightness and contrast depends on it. The excessive light energy causes a displasia of the photochemical processes in the amphiblestrodes and inhibition of its functions. A lack of light energy complicates the accommodation. In other words, the eye adaptation to the clear vision of objects placed at different distances from it. Contrast of the monitor display also depends on the ambient light, and in case it changes it causes an additional strain of the eyes.
Low frequency monitor (less than 75 Hz) evokes a feeling of flashing images; at that the eye muscles overstress. The frequency of image more than 100 Hz do hurts to eyes as well. This results in a rapid exhaustion of eyes and a strong headache.
Physicians introduce three ways to prevent eye strain from the computer: maintenance of the work hygiene, the approach of the monitor display to the natural and the overall improvement of the visual system (Heiting and Wan). In particular, one should avoid the excessive light of the display by the outside light. One should not forget to wash the dust from the screen. For general lighting one should use the fluorescent lights; the incandescent lights should illuminate only the documents, books and keyboard.
According to the research of U.S. ophthalmologists, as a matter of fact, the color of the monitor affects the visual efficiency. The most optimum color of the casing is beige. In order to make the screen display gentle for an eye, experts advise to use a font sizes 0.46 – 1.75cm at a distance of 50 cm from the screen. Artistic fonts and graphics quickly tire the eyes. It was already determined by researchers that the best fonts for observation are Arial and Verdana.
One should pay attention to the most successful combinations of colors of the subject and the background (Heiting and Wan). During the simultaneous operation with the image on the screen and documents on white paper it would be viable to use a white screen with black lettering. If a person is working with colored objects on paper, color of the screen should be in the blue-green part of the spectrum. In case he/she is working only with the screen, it is viable to use a light blue background and black typescript. Physicians advise to work at a distance of 40 – 60 cm from the screen while the top edge should be positioned at eye level or slightly below in order to provide a view from the top to down; in such case eye strain is less. In addition, it is more preferable to use flat monitors that do not distort the image; thus, do not create additional difficulties for human eyes work.
One should remember that the period of visual load and the rest should be in the ratio of 3:1. Every 45 minutes of work one should make the 15-minute breaks and exercises for the eyes with special massage (Heiting and Wan). In case there is still a need to use eye drops, then it is better to choose them from the class of moisturizers that do not desiccate the mucous membrane of the eye and are not addictive.
New computer programs that help to remove the visual fatigue were developed. They consist of complex motional exercises and visual training. Programs run on a computer at regular intervals penetrate the work of currently run applications and programs.
In general, the modern person is surrounded by so many hazards even of a low intensity that his body is quite resistant to the effects of each of them independently, but cannot withstand the onslaught of all the hazards. That is why doctors are tightening the requirements for the maximum allowable levels of these factors and highlight the importance of studying the problem of complex influence factors of low intensity.
Today, there is a discussion among scientists around the world concerning the damage to the eyes caused by viewing modern TVs and sitting at the modern computers. Many owners of large format plasma screens and LCD monitors are convinced that the latest generation of modern computers does not have a negative effect on the organs of vision. Dealing with what is true or false, leading ophthalmologist in the United States of America stated the next. According to the experts, in the course of numerous studies it was authenticated that monitors and television sets, designed by the latest technology, do not harm the eyes independently on the distance a person watches them (Barett). A key factor is the time of viewing and using of the computer.
Physicians advise that in case of dryness and pains in the eyes, lacrimation while sitting the front of the screen, one should break away from the computer or TV for a while, do exercises for eyes and give a short rest his/her eyes. There is a strictly regulated time of watching TV and sitting at the computer for children, which is no more than 3-4 hours a day.