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Health & SafetyYou have chosen to have a look at the health and safety section, which is a very overlooked aspect of computing. Since you are interested in building, upgrading or repairing your PC yourself (otherwise you would not be here), I can assume that you have the kind of interest in computers that goes beyond simple office work, so I'd better make this section good. There are various aspects of computing that are arguably affecting our health, starting with HCI (Human Computer Interface) right down to Electromagnetism. I have tried to cover most of the important issues about health and safety, you'll have to decide for yourself any it apply to you.
It should be apparent by now that illness associated with computer use can rarely be attributed to a single cause or factor. More commonly, the complaints that computer users report can be traced back to a vast array of elements, from the specifics of a piece of equipment to the vagaries of attitude and environment. It follows, therefore, that the environment in which we compute must be one of the possible elements, which contribute to our health and well being (or lack thereof).
Many of the 'broader' repetitive strain injuries-head, neck and shoulder-are the result of more factors than simply fast, repetitive typing. Poor posture, uncomfortable furniture and a poorly laid out environment all take their toll on the hapless computer user. The workspace (also referred to as working environment or workstation) is a rich combination of these things. The immediate workspace comprises personal working habits, the shape. And height of the desk, design of the chair, position and angle of monitor, accessibility of the mouse and keyboard and presence or absence of other items (such as document holders) on the desk. The wider workspace also embraces the location of windows, the temperature and humidity of the room, noise, and lighting levels. All these elements contribute to an individual's susceptibility to various health problems. The effects may not be apparent immediately, but the cumulative effects of years spent working at the PC can be damaging.
Lighting is a surprisingly rich subject of study, both technically and artistically. It also has a profound bearing on our effectiveness as we use computers. There are many terms associated with lighting issues, but the ones of most relevance to visual health are illumination and luminance. Illumination is the measure of the stream of light falling on a surface, and its unit of measurement is the lux. A small candle gives off approximately one lux of light; a bright, sunny day may reach up to 100,000 lux. Normal office work falls into the 100 to 500 lux range, although delicate, detailed work justifies a workplace as bright as 3,500 to 5,000 lux. Luminance is the measure of brightness of a surface in effect, the amount of light coming from a surface-and is greatly affected by the reflective powers of that surface. Many computer users display a preference for dim lighting to achieve better screen contrast. Fine in itself, this becomes a problem if close paper work is also required. In most cases, the best solution is reduced overall lighting with an adjustable lamp that can be focused on reading materials but not on the monitor screen. The most painful effect of poor lighting is glare. Glare is caused by the specula reflection of excessive light from the glass surface of the monitor screen. When the eye is trying to focus on information displayed on the screen, the pupil dilates to increase acuity. Glaring light causes the pupil to constrict, however, and the conflict between the papillary muscles is thought to be the cause of much eye irritation and headache. Much research has been done on the levels of lighting which are appropriate within offices, although the requirements are quite different where computers are used with any regularity. Computer users experience greater contrasts in light and dark, both on the screen and in the surrounding environment, making it important to achieve the optimum balance between . screen characters and background (contrast). Extreme contrast, as discussed above, only helps legibility when ambient lighting is carefully controlled, since any extreme luminance from the screen will contrast unpleasantly with the surroundings. Optometrists recommend an illumination level on the desk surface of 300-500 lux, which provides the best compromise between lighting sufficient to read paper by, and for comfortable contrast with the monitor. Light much dimmer than this may make the monitor display clearer, but it makes paper much harder to read. It also has a subtle psychological effect and can make users depressed or sleepy. If most of the desk work involves the monitor, it is acceptable to work at the lower end of the recommended illumination level. Lights should be turned up if a high proportion of paperwork is involved. The source of light is an important part of the overall lighting plan, with direct and indirect sources being typical in an office. Direct light sources send up to 90 per cent of their light towards targets in a single cone of concentrated light; whereas indirect light sources throw the vast proportion of their light onto the walls and ceiling first, from where it is reflected back into the room as a diffuse scattering of light. Direct lighting (spotlights, focused lamps) is useful as an illuminator of specific areas which need to be clear faint documents, for example-but it also induces sharply contrasting areas of dark and shade. Indirect lighting achieves a far smoother and more even effect, eliminating glare and shadows. Fluorescent lighting is one of the more harmful sources of direct lighting, since it is composed of flickering light. The flicker is generally a minimum of 100Hz, which is well above that of most monitors and therefore imperceptible. Nonetheless, it is still within the range of flicker which induces activity within the optic nerve and cannot be ruled out as a contributor to eyestrain. If fluorescent lights are already part of an office layout, flicker can be greatly reduced by using two bulbs together, adjusted to flicker out of phase with one another. This phase-shifting, as it is known, has the effect of turning one bulb on as the other goes off, creating an almost constant light. Fluorescent tubes can be used without any further precautions. If there is more choice of lighting, one of the most effective ways of ensuring the visual health of computer users is up-lighting. The light source should be positioned to point upwards-either directly, or via a shade which deflects light upwards. Up-lighters positioned in corners have the added advantage of two opposing walls which further diffuse the light around the room. Where possible, up-lighters need to be located at least seven feet above the ground. This ensures that the deflected light is still powerful enough to be thrown back evenly by the reflecting surfaces, and it also eliminates the possibility of bright reflections, caused by light sources located at head level, appearing on monitor screens. For maximum comfort, the best combination of lighting for the computer user is diffuse ambient light, generated by . indirect sources and not exceeding 500 lux. If paper work is a regular part of the job, lighting levels should tend towards 500 lux, or be supplemented by a small, adjustable spotlight for close reading. The aim is to reduce contrast and glare which force the eyes to work much harder.
The human being is a self-regulating creature, equipped with mechanisms for generating internal stability and responding to external changes. Temperature and humidity are important climatic variables which affect performance at work, particularly in the office environment. Normally, temperature is regulated by internal metabolic processes which conserve or expel heat energy through the dilation or constriction of blood vessels. As body temperature begins to rise, the heart pumps more blood to the cooler surface of the skin where it is dissipated. As this process accelerates, the effect is a reddening of the skin where the local blood vessels dilate to bring more blood to the surface. If blood cooling is not fast enough the skin begins to sweat. As the moisture evaporates, it draws on the heat energy of the skin, cooling it down. In cold climates, the peripheral blood vessels constrict, retaining blood (and hence heat) deep within the body and major organs. Deep body temperature in a healthy person rarely varies by more than a fraction of a degree. Alongside electromagnetic emissions, computers generate heat when they are switched on. Electrostatic charges build up around the screen, aggravated by very dry conditions which allow dust particles to gather in the air. In a large office, the combined effects of heat generation and electrostatic discharge can place a large and expensive load on air conditioning systems. If no such air conditioning exists, employees working in this type of environment quickly become very uncomfortable. Excessive humidity (moisture) in the atmosphere prevents the evaporation of sweat, leaving people feeling stuffy and lethargic. More commonly in a computing environment the problem is excessively dry air, which leaves skin feeling roughened and membranes dry and irritated. The inside of the nose can develop a burning sensation and the eyes often feel red and scratchy. Temperatures much above 22 degrees centigrade have quite marked effects on human performance in the office. The concentration span declines, people performing skilled tasks make more mistakes and may become irritable or lethargic, depending on temperament. The temperature range at which people are comfortable is surprisingly narrow and very precise, rarely varying by more than two or three degrees from the mean of 20 degrees centigrade. Women tend to prefer a slightly higher temperature than men. Cooling and comfort can be aided by good ventilation, although draughts can be a nuisance. The feet and neck are particularly sensitive to draughts, and most people prefer air currents which come from in front than from behind. Humidity is essential in computerised offices, and most studies recommend relative humidity of 40-50 per cent, with'30 per cent as the absolute minimum. Noise is an inevitable part of office life, and most of us are able to filter out and ignore sounds which mean little to us. Noise becomes a nuisance when it exceeds levels which we can ignore, even when the content of the sound is irrelevant to what we are doing. Our ability to hear serves primarily as a means of communication between individuals, but it has a secondary role as an alarm mechanism. Unexpected, unfamiliar or loud noises trigger pathways to the brain which increase alertness and divert mental energy from the task in hand to the interpretation of sound and preparation of an appropriate response. If this happens regularly, it becomes more and more difficult to concentrate. Being in a constant state of mild alarm is also exhausting, making comparatively mild noise levels distracting during office work. A comfortable level of sound for most people is between 45 and 50 decibels, where the decibel measures the pressure caused by sound waves on the human ear. Computers and computing equipment have introduced new sources and levels of noise to the office environment, some of which considerable exceed this level. Printers are the worst offenders, with matrix and daisy wheel printers producing sound levels of up to 75 decibels, although a hood can reduce this to a more bearable 60. Computers themselves make almost no noise, although the cooling fan within the system unit can be clearly heard. At 40 decibels it is rarely remarked upon, but some computer cooling fans reach levels of 50 decibels or more. If the office is quiet, or if there is more than one computer, the noise level can become quite distracting. Some computer manufacturers are now going to considerable lengths to reduce the noise levels of their products. Greater insulation within the unit itself damps noise, and smaller fans are being used. Little can be done to reduce any further the sound of a daisy wheel printer with a hood, although laser printers are almost completely silent. The use of computerised sound in some offices is becoming a real possibility now, as technological developments continue. Computers have been able to make sounds for many years, but this has rarely been applied to the office environment. The development of sound cards could change this. Sound cards can be slotted into a system unit rather like a video card, and with the appropriate software, enable a computer to play any type of recorded sound. Music, voices, animal noises, electronic effects-pretty well anything. This ability has generally been restricted to computer games, but more and more companies are trying to develop serious business applications for computerised sound. It is now possible to control some applications software through the use of sound-instead of selecting 'Open' from a drop-down menu to open a new file, or clicking on the word with a mouse, you can simply say 'open'. Similarly, it is possible to format text by saying 'bold', 'italic', or 'spell'. For more complex commands, it is possible to 'train' a computer to recognise a specific voice intonation, which increases the accuracy of its understanding. By talking directly to a computer in this manner, it is possible to shave precious seconds off many routine computing tasks. Sound is being used to great effect by organisations like the Royal National Institute for the Blind, for whom it has a direct benefit. It is less easy to foresee a large uptake of sound cards in open plan offices, where the cries of 'bold', 'open' and 'quit' would elevate the decibel level way beyond acceptable limits. Not only is this annoying in itself, but would surely be tremendously irritating to those around. The speakers would also suffer: if not from sore throats, then from the wrath of their colleagues. The question of sound interference is also a serious one: no one will be pleased if a colleague's sudden cry of 'Ouit' shuts down all the neighbouring computers as well as their own, and the use of headphones and microphones is unlikely to be welcome as an alternative.
Electromagnetism and
the Computing Environment
What is Electromagnetism? Electromagnetism is a form of one of the fundamental forces of the universe: electromagnetic radiation. In its natural state, electromagnetism comprises both magnetic fields and electrical charge which combine to form electromagnetic waves. The two types of fields - electrical and magnetic - are related and arise from the same phenomena, but they have individual distinguishing characteristics:
Electromagnetic waves are generated every time electricity or magnetism changes direction or strength. Since electricity is just the movement of electrons, and electrons are part of every atom that surrounds us, we are constantly bathed in a low level of EM radiation. Natural varieties include light, infrared and ultraviolet, cosmic rays from distant exploding stars and radio signals from thunderstorms. Most modern technology relies on or produces electromagnetic radiation-radio, TV, microwave and X-ray are all examples. Electromagnetic radiation constantly varies in strength from zero to the maximum level of a particular signal and back again. The speed at which it does this defines the frequency, and thus the effects, of the radiation. A frequency of zero means the field is not moving at all - this is called an electrostatic field, in other words, a field where the electrons are static. Just above zero are the slowest forms of genuine electromagnetic radiation, called extremely low frequency (ELF) and very low frequency (VLF) radiation respectively. These have a repetition rate of between a couple and a few thousand times a second. Electrical appliances, house wiring, TVs and monitors radiate most at ELF and VLF. Above that in the radio spectrum are LF, MF and HF, for low, medium and high frequency. These are used almost exclusively as radio communication bands, and so most computers are shielded at these frequencies to prevent radiation and interference. The same is true of VHF and UHF-very and ultra high frequency-which are used for TV and stereo radio, walkie-talkies, mobile phones and the like. Above UHF is microwave radiation, then comes infrared, visible light, ultraviolet, X-rays and gamma rays. Although computers radiate some power at all of these frequencies, the health effects are well known and the levels of radiation are kept very low, where appropriate.
Since computers are electrically powered they must emit radiation of some sort-but how is it different to the negligible and harmless levels of radiation emitted by other domestic and business electrical appliances? As far as the system unit is concerned, it is not. The only source of emissions within the system unit is the power supply, which conforms to the same specification as any other electrically powered apparatus. The real threat comes from the monitor, which contains the control mechanisms for displaying screen images. An electron gun which receives instructions from the graphics adapter card fires electrons at the phosphor coated screen, causing the phosphor to glow. This process is harmless; it is the mechanism controlling the movement of the electron gun which represents a potential health hazard. The beam of electrons is accelerated and directed towards the screen by a high voltage transformer, but it requires extra navigational power to move across and down the screen during raster scanning. This is achieved by a horizontal and vertical deflection system: two sets of coils are wound around the neck of the cathode ray tube and, when the monitor is switched on, electric currents flow through these coils (or yokes) and generate powerful magnetic fields. The magnetic power of these coils is able to deflect the electrons as they are fired from the gun-a horizontal deflection coil moves the beam from left to right; a vertical deflection coil moves it from top to bottom. Each time the electron beam reaches the right-hand side of the screen, a synchronisation pulse causes it to 'fly-back' to the left-hand side while the vertical deflection coil pulls it down a line. Typically, monitors produce 6262 line pictures a second and the electron beam travels back and forth across the screen more than 15000 times a second. This amounts to a horizontal scan frequency - or line refresh rate - of 15000 hertz (15 kilohertz) ; and a vertical scan frequency - or frame refresh rate (the entire picture) - of 60 hertz. This process of image creation in the cathode ray tube gives rise to three types of monitor emissions:
The powerful field of electromagnetism generated by the deflector yokes is the source of radiation thought to be harmful to living cells. The pulsing action of the fly-back mechanism generates a corresponding electromagnetic pulse of VLF radiation; whilst the slower vertical deflection coil produces a strong pulse of much lower 60 hertz ELF radiation. The monitor is designed to minimise the extent to which such radiation can hurt-a lead lining inside the screen eliminates X-rays almost completely and the glass and casing of the monitor absorb the vast majority of the remaining VLF radiation. Some, however, leaks out-mostly from the back, where the coils are located, some at the side and a little at the front. What this means, in physical terms, is that the cyclical movement of the electromagnetic field continues to act beyond the confines of the monitor. An electromagnetic field is composed of charged particles oscillating (using energy to move back and forth) at a frequency measured in hertz. The frequency at which particles in a particular field oscillate (60 hertz for ELF and 15 kilohertz for VLF radiation) is called the resonant frequency, where resonance describes the frequency at which particles will oscillate most freely. All particles (whether in solid, liquid or gaseous form) have a resonant frequency - what the frequency is depends on the chemical composition of that particle. When a field encounters panicles which share its resonant frequency, they too will begin to oscillate at that frequency. The effect is not unlike the movement of a poorly designed suspension bridge: if air currents have been channeled into a particular frequency (by the location of nearby hills, for example) and hit a suspension bridge, the bridge may begin to move in the same way as the air current. If the two prove to have the same resonant frequency, the bridge will assume the patterns of oscillation of the air and use its energy to move. The 'ripples' of the bridge will continue to increase in size until the whole structure collapses.
Very Low Frequency radiation Quite how low-frequency radiation affects cells is still not entirely understood. VLF signals, which range from 3,000 to 30,000 Hz, are emitted primarily by the deflection yokes of monitors and have so far escaped the glare of bad publicity. This does not make monitors entirely innocent: all the recent studies that have given monitors a clean bill of health examined only VLF radiation.
Extremely Low Frequency radiation Extremely low frequency radiation is at the lowest end of the electromagnetic spectrum (hence the name). Most physicists define ELF as the radiation band from 30 hertz to 300 hertz, although it is often extended to include any frequency below 30,000Hz (and therefore VLF). Strictly speaking, ELF is not true radiation, but captive electric and magnetic fields generated by strong electric currents in power systems, appliances, and other electrical equipment (including monitors). In normal circumstances we are constantly bathed in very and extremely low frequency radiation. It comes primarily from electricity mains, but also arises naturally from sunshine, fire, hot surfaces and the earth's own magnetic field. Naturally occurring radiation has no effect on living cells because its resonant frequency is very different from that of the particles found there-this does not seem to be completely true of the artificially generated electromagnetic fields associated with monitors (or electric blankets, hairdryers and portable telephones, for that matter). Research into the effects of ELF radiation is increasing, and the phenomenon is now being linked with a variety of health issues. Work is done through laboratory studies made on cell cultures and animal tissues, and through epidemiological surveys which have attempted to find a common link between the backgrounds of sufferers.
Electromagnetism and Health issues
Cancer is one of the most serious potential side-effects of exposure to ELF radiation, and most of the studies in this area have concentrated on exposure to power lines rather than computers. Research findings in this area seem to suggest that such exposure accelerates the process of cell division, increasing the likelihood of 'mistakes' occurring as cells replicate themselves. Furthermore, the rate of increase in cells which are already cancerous is far greater than in normal cells-in other words, exposure to ELF radiation increases the likelihood that a cancer may develop and also encourages the growth of cancers which are already present. Normal immune system defense mechanisms are overwhelmed by this acceleration and cannot cope, allowing malignant growths to develop. As a further complication, studies of rats under ELF exposure point to the suppression of the hormone melatonin as a factor in the development of cancer. Melatonin controls the biological clock, enhances the immune system and retards the growth of cancer cells. If it is suppressed, of course, the growth of such cells can continue unchecked. Other theories concentrate on cell membrane activity under the influence of ELF fields. A common resonant frequency and the consequent mimicking of normal cellular processes may be the features of ELF which enable it to contribute to the development of cancer. What appears to happen is that some ELF reactions occur at membrane sites which subsequently exhibit an increased tendency to behave as receptors for cancer-promoting chemicals. In a sort of double negative effect, ELF fields also appear to increase the chemical activity of a compound known as ornithine decarboxylase, a process which has previously been associated with the onset of cancer. The electric field strength of some computer equipment, even at abnormal working distance, appeared near the level at which ornithine decarboxylase activity was found to increase in some studies. In another study, a similar field intensity was found to increase the toxicity of the white blood cells (lymphocytes) which specifically attack cancer cells in mice.
Miscarriage and Pregnancy Problems The possibility that ELF radiation is connected to pregnancy problems is deeply alarming, and has generated more studies than almost any aspect of computer use. Alarms were first triggered at a newspaper, the Toronto Star in Canada, between May 1979 and May 1980. Four women working at the newspaper gave birth to children with different defects a surprisingly large number-which first led to the association of abnormal pregnancies with monitor use. A number of American studies took up the banner, rapidly revealing similar statistics across the country. At the Sears Roebuck Company in Dallas, eight out of 12 pregnancies in a year were abnormal and the Attorney General's office in Toronto reported a miscarriage rate of 52 per cent over two years. In the Solicitor General's office in Ottawa seven abnormalities were reported in seven consecutive pregnancies among monitor users. A rush of research in the mid-1980s failed to find monitors guilty. A Finnish study which drew on the entire country's records of . birth malformations failed to find any link between that and monitor use; in Canada and Sweden, two major studies could find no evidence for an association between computer use and any kind of pregnancy problem. A later study, however, did find a link. In 1988, a carefully controlled study was carried out at the Northern Kaiser Permanent Medical Care Program, a health maintenance organisation in Oakland, California. Researchers, led by Marilyn Goldhaber, followed the fortunes of 1,583 pregnant women who attended obstetrics and gynecology clinics run by the centre, paying particular attention to the environmental hazards these women routinely encountered. Their findings gave cause for concern, expressed by the researchers as a correlation between an increased rate of miscarriages for women who had used VDTS (visual display terminals) for more than 20 hours per week during the first trimester of pregnancy, compared to other working women who reported not using VDTS. The results are not clear-cut, however, with some critics observing that they were not statistically significant. In recognition of this, the researchers themselves drew particular attention to the possibility that women who had adverse pregnancy outcomes may have over-estimated their exposure to visual display terminals, whilst women with normal births may have under-reported theirs. They also acknowledged the role of other factors which the study did not measure, such as poor ergonomic conditions or job related stress. In the same way that stress plays a role in our susceptibility to repetitive strain injury, it is undoubtedly a factor in the incidence of miscarriage amongst computer users. One company altruistically offered its pregnant employees lead aprons to wear during computer use, but the practice was abruptly halted after the women admitted the lead aprons were far more stressful than the monitors. At least nine subsequent studies have been unable to find a positive association between abnormal pregnancies and monitor usage. In the same year, 1988, also in America, the National Institute of Occupational Safety and Health (NIOSH) studied 882 pregnancies and found that pregnant women who spend a significant amount of time in front of monitors do not run a higher risk of miscarriage. The following year, a study carried out at the University of Toronto showed no association between miscarriages in mice and the electromagnetic fields emitted by computer monitors.
An unusual and rarely reported set of health conditions thought to be linked to electromagnetic radiation is rashes, usually on the face but sometimes on other parts of the skin. Facial rash was first reported in 1978, almost ten years before the introduction of standards regulating monitor emissions. A team of computer operators working in a factory in -London had been using new computers for over a month, when one full-time operator complained of red patches on his cheeks. Two other operators later developed the condition, which then included raised bumps, itchiness and redness. Similar cases were reported in 1979 in Norway, where operators reported reddish patches, dryness, and tingling of facial skin, which was likened to sunburn. Symptoms appeared up to two hours after beginning work with a computer, and disappeared around two hours after switching it off. Onset was marked by sensations of the affected areas being patted or stroked with a feather. Subsequent studies, although few in number, report a consistently higher incidence of skin rash in computer users compared to non-users. In many cases, skin rash occurred in users who had also reported eyestrain and repetitive strain injuries. Fears originally centred around radiation as a cause of skin rash, but research suggests a more indirect relationship. In work locations where several people reported skin rash, researchers also noted new synthetic carpets or recent building work. In both situations, there were abnormally high levels of sub-micron dust particles in the air. The electrostatic fields generated by monitors have already been shown to attract dust particles by virtue of their opposing charges and this is exacerbated by dryness-low humidity. Where the proportion of dust is high anyway, there will naturally be a higher than normal concentration of particles around a monitor in use. If the particles contain natural irritants-synthetic fibres, brick dust, some chemicals or even traces of asbestos-the likelihood of an allergic reaction is much higher. In each of these cases, removal of the irritant fibres was associated directly with a decline in reported skin rash. So, although the electrostatic emissions of computers do contribute to skin rash, it is the high concentration of irritant particles, drawn to an electrostatic field, which actually causes dermatitis.
Although monitor emissions have been linked, however tenuously, to damage or irritation of specific parts of the body, it is rare for users to report generalised sensitivity to electricity. In recent years, however, numbers have been increasing and nearly all the sufferers are habitual computer users. First documented in Sweden in 1987, electrical hypersensitivity is now an identifiable condition with potentially serious consequences. The first indication that a person is becoming hypersensitive to electricity is minor irritations associated with regular computer use. Typically these include a warm or burning sensation on the face whilst working with a monitor, and many of the symptoms of skin rash described above. In the hypersensitive, the rash may spread across the body to skin not directly exposed to the monitor. Dryness and irritation of the eyes is common too. In the early stages of hypersensitivity these symptoms fade once the computer is switched off, but they become more persistent and prolonged quite rapidly. The discomfort becomes worse until the facial skin feels as if it is on fire, and other, more alarming, symptoms become apparent. These include dizziness, headache and nausea, tooth and jaw pain, aching muscles and joints and even cardiac palpitations. Other sufferers describe a feeling of impending flu which never quite breaks out. These symptoms are associated exclusively with computer use at first, but as they increase in severity they can be triggered by all sorts of electrical apparatus. Ordinary television sets, fluorescent lights, cookers, vacuum cleaners and electrical cables cause the same reaction, greatly hampering everyday life. In the office, fax machines, pipelines, computer wiring and liquid crystal clock faces trigger unbearable symptoms. In extreme cases, even daylight, white-painted surfaces and paper handling can trigger a range of severe and painful symptoms. Electrical hypersensitivity is more than an inconvenience. Extreme cases can be severely debilitating, restricting the sufferer to a life of darkened quiet in an environment free from electrical fields. Work, shopping and normal life become impossible for the hypersensitive: interaction with household appliances, electrical cables-even radios-can become unbearable. Inevitably, whole families suffer. Some leave their homes and relocate to remote areas far from electrical activity, where they live by candlelight and cook on wood-burning stoves. Unsurprisingly, many sufferers have to go alone, or retreat to caravans near the family home. Sufferers of electrical hypersensitivity react to a far broader range of energy within the electromagnetic spectrum than normal people. Extremely and very low frequency radiation is the first irritant, but symptoms are also triggered by low, . medium and high frequencies (radio waves) and naturally occurring radiation such as infra-red and visible light. Swedish research has shown a link between reported feelings of illness and spots of particularly high electromagnetic activity within the homes of people experiencing electrical hypersensitivity; symptoms worsen considerably when, for example, a neighbour switches on a television set next door. Despite the severity and implications of electrical hypersensitivity, it is not a widely recognised condition. Provocation studies conducted in Sweden in 1993 have been inconclusive: researchers attempted to provoke the symptoms of electrical hypersensitivity by exposing sufferers to electromagnetic fields. Sometimes the field was switched on and sometimes it wasn't-patients were asked to detect when it was on. Out of thirty hypersensitive subjects who took part, none was able to detect a field with any consistency-successful detections were few enough to have been due to chance alone. Similar studies have had mixed results, with a small number of patients achieving a higher detection rate than can be explained by chance. Others put the condition down to purely psychological factors, having failed to find an objective link between electromagnetism and symptoms of hypersensitivity. Instead, they propose a link between the symptoms and the personality of patients normally hard-working, conscientious and frustrated or under-appreciated.
Electromagnetism - Harmful or Not? The evidence implicating computer monitors as a cause of cancer, skin rash, miscarriage or electrical hypersensitivity is weak, and no scientifically significant results for any such health risks have been reported. Nor should it be forgotten that the difficulties of truly controlling large-scale epidemiological studies are monumental-so many other variables affect the individuals participating that it becomes almost impossible to say with certainty that any one factor is the cause of any one event. All the studies to date are co-relational rather than causal, that is, they can show that there is some health effect associated with computer use, but cannot prove a true cause-and-effect relationship. The radiation from the computer terminals could be contributing to health problems, or something else about monitors, or the way a particular study was conducted could have influenced its results. Most importantly, it is certainly not clear what the specific mechanism is by which electromagnetic radiation could affect a biological process such as pregnancy. The simplest theory proposes a mechanism similar to the theory of accelerated cell division thought to be implicated in the development of cancer. Since fetal tissue is in a state of almost constant and total division, the possibility of errors occurring during uncontrollably accelerated growth is increased enormously, compared with the risk to the cells of a fully grown adult. Such errors are thought to be the triggers of spontaneous miscarriages. The other illnesses discussed here certainly do not require exposure to a computer in order to occur, and the 'natural' mechanisms by which they are triggered are no better understood than the computer-related ones. So although the computer cannot be completely cleared of involvement in health problems, neither can it be unequivocally blamed. | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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