Important precaution related to monitor.

          

Because your monitor interacts with you like no other part of your
computer, it is important to observe some basic rules:

·                     Do not open the monitor! There are no user serviceable components inside. There are Dangerous High Voltages inside, even when the power is OFF. Contact your dealer if the monitor is not operating properly. Keep children from drooping or pushing object into the monitor’s cabinet openings. Some internal parts carry hazardous voltages.

·                     During a lightning storm or when the monitor is to be left unattended for an extended period of time, unplug it from the wall outlet.

·                     Don not allow anything to rest upon or roll over the power cord, and do not place the monitor where the power cord is subject to damage.

·                     Don not use this monitor near water such as near a bathtub, washbowl, kitchen sink, laundry tub, in a wet basement, or near a swimming pool.

·                     Never back the bottom ventilation slots by placing the monitor on a bed, sofa, etc.

·                     Never place the monitor in a built-in enclosure unless proper ventilation is provided.

·                     Never cover the openings of the monitor with cloth or other material.

·                     Never place the monitor near or over a radiator or heat source.

·                     Always use a slightly damp (not wet) cloth when you clean your monitor. Do not use an aerosol directly on the picture tube because ‘over spray’ may cause electrical shock.

·                     Always unplug the monitor before cleaning the face of the picture tube.

·                     Last but not least and probably most importantly: place your monitor ergonomically.

Some more Tips

·                     If you have an energy star rated monitor, make sure it is plugged directly into the power socket (and leave the power socked switched on, unless you go on holiday). Energy star rated monitors don’t like being switched off any more but switch them off when the computer sends the signal. So do your monitor a favor and leave it plugged in, it can take care of itself.

·                     Take the time to calibrate your monitor properly. Uncalibrated monitors can distort colures and shades. If you want to produce professional quality work you need to have accurate screen representation.

·                     If you leave your computer running unattended for long periods, use a screen saver. Screen savers not only protect your work from envy eyes but also most importantly protect the screen from burning out.

·                     Download a monitor checker to test and calibrate your monitor frequently. Monitor checkers are usually free of charge. Most up market graphics cards even provide their own test utilities.

+

How computer emits Radiation?

          

  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 arrow 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 synchronization pulse causes it to ‘fly-back’ to the left-hand side while the vertical deflection coil pulls it down a line. Typically, monitors produce  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 rat (the entire pictures)-of 60 hertz.

            This process of image creation in the cathode ray tube gives rise to three types of monitor emissions:

·                     X-rays, caused by the impact of the electron beam on the inside of the glass

·                     Harmless electrostatic potential caused by positive voltage on the glass.

·                     Alternating electromagnetic fields caused by the power supply and deflection yokes.

The powerful filed of electromagnetism generated by the deflection 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 minimize 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 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 bride, 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.

+

Computers and possible Health Problems.

            

The evidence implicating computer monitors as a cause of caner, 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.

+

Computer and the Computing Environment

            Working with computers is not a hazardous business if you pay attention to your posture and take regular breaks from the keyboard. However, computers generate electromagnetic fields, which are know to affect the normal function of living cells. We don’t know-weather these emissions have any effect on human tissues, or what the consequences of exposure are, if there are any at all, but many scientist argue about this. And where there is an argument, there might be a reason.

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:

·                     Electric fields generate a potential (a voltage), are measured in mill volts or volts per meter, and are relatively easy to shield against by using conductive materials.

·                     Magnetic fields generate a current (amperage). These fields are measured in milliamps per meter or sometimes in related units of gauss, and are difficult to shield against.

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 distend exploding stars and radio and radio signals from thunderstorm. 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 know and the levels of radiation are kept very low, where appropriate.

+

The work space while working in computer.

            Health and Safety is a much overlooked aspect of computing. There are various aspects of computer that are perhaps affecting our health, starting with HCI (Human Control Interface) right down to Electromagnetism.

            Since your are interested in building, upgrading or repairing your PC yourself (otherwise you would not be here), we can assume that you have the kind of interest in computers that goes beyond simple office work. With this kind of interest in computers and computer hardware, you will spend a considerable amount of time in front of your beloved (or ‘behated’) piece of equipment, during which your computer has a considerable impact on your health.

The Work Space

           

It should be apparent by now that illness associated with use of computer scan rarely be attributed to a single cause or factor. More commonly, the complaints that computer user 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 of).

            Many of the ‘broader’ repetitive strain injuries-head, neck and shoulder-are the result of many 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 so make sure you have selected your working environment as carefully as the components for your PC.

Lighting and Glare:

          

  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.

Temperature and Humidity:

           

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 pain. 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 computerized offices, and most studies recommend relative humidity of 40-50 per cent, with’30 per cent as the absolute minimum.

Noise at Workplace:

           

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.

+