Working With Computers

Conventional computer systems have used cathode ray tube (CRT) technology for the display. Thin film transistor (TFT) liquid crystal displays (LCDs) have become an increasingly popular technology. LCDs offer many advantages over CRTs, including:

• faster search times for text and reduced errors;
• greater postural variety during computer work;
• freedom from flicker and geometric image distortions at the screen edges;
• uniform screen brightness and substantially less glare;
• thinner and lighter displays which require a narrower work surface at the same screen to eye distance and are easier to reposition; considerably less energy use and heat emission;
• better screen privacy because they cannot be clearly viewed from acute side angles; and
• no VLF/ELF electromagnetic radiation emissions associated with the scanning electron beam required for a CRT.

Reading without adequate light or reading small print over long periods of time can sometimes cause eye strain. It is generally believed that visual fatigue does not contribute to long-term deterioration of the ability to see, although eye strain can cause eye irritation, watering and reddening of the eye lids or blurred vision. Some computer operators may suffer headaches associated with eye strain, particularly if the head and neck muscles are held in a static position. However, these complaints are also described by people performing other close visual tasks. Looking away from the computer to a far spot, walking away from the screen and giving the eyes some exercise, such as blinking, can decrease the effects of long periods of concentrating on a screen. A dry air conditioned environment can contribute to eye discomfort.

People with pre-existing visual defects may be more likely to suffer eye strain from using screens than those with properly corrected vision. Current research does not indicate evidence of screen use causing cataracts or other permanent eye problems.

The purpose of eye tests for computer users is to identify and correct pre-existing visual defects that may cause discomfort as a result of the visual concentration needed for many screen-based tasks. Some organisations have an agreement for vision testing for all computer users and others may provide a subsidy for prescription glasses.

See Comcare Australia’s Fact Sheet No 8 – September 1995 Visually Demanding Tasks and Guidelines for Eyesight Testing and Optical Correction for Visually Demanding Tasks.

Many middle-aged workers suffer difficulty with close work, known as presbyopia, and require spectacles for correction. Bifocals are designed to correct vision when looking down through the lower portion of the lens for close work. This may be suitable for reading a document, however, when reading information on a screen, computer users are generally looking horizontally over the section of the lens designed to correct their vision. Many users lean forward and tilt their chins up to look through the lower part of the lens. This unnatural posture is unsatisfactory and can result in neck discomfort.

In these circumstances, spectacles with full corrective or multi focal lenses should be used and working documents located between the screen and keyboard or alongside the screen to ensure the same focal distances for both. This reduces the likelihood of the operator adopting unnatural neck postures. Computer users concerned about their vision or spectacles should seek advice from their medical specialist.

Approximately 0.5% of the population has epilepsy. Up to 3% of them (that is, 0.015% of the total population) may be sensitive to flickering lights or certain patterns. Children are more likely to be affected than adults in this way. The screen refresh frequency of CRT screens and of fluorescent lights is generally higher than the flicker frequency associated with this condition, so instances of this issue in offices are generally rare. LCDs should not affect epilepsy sufferers as they do not flicker.

If a person with epilepsy is starting a job involving office work, consideration should be given to the many factors that may aggravate this condition. If there is concern regarding flickering of a screen or lighting, a medical specialist should be consulted.

Computer screens based on CRT technology are designed to emit visible radiation (light) with a brightness that is adjustable by the operator. In creating the display, small amounts of other types of electromagnetic radiation (EMR) are also generated at extremely low frequencies, including radio waves, infrared (heat), ultraviolet and X-rays. Other sources of EMR in general life include electric blankets, hair driers and other electrical appliances used daily. LCD screens only emit visual radiation.

Possible health effects of radiation include:

• Eye problems – short-term visual discomfort may occur, but research so far does not indicate evidence of any permanent eye problems.
• Skin disorders – ultraviolet radiation emissions from CRTs are extremely low and are not considered likely to cause skin disorders.
• Cancer – although concerns have been raised that radiation from computers can cause cancer, research has failed to establish any causal link.

There have been allegations of reproductive problems associated with working with computers. Reliable epidemiological studies conclude that the incidence of adverse pregnancy outcomes among computer operators is not significantly different from women who do not work with computers, so there is no firm evidence to support these allegations. Generally, exposure levels of computer operators to any radiation emissions are no different to those of other people in the community, since CRTs emit such low levels and LCDs do not emit radiation. There is currently no evidence of risk to either male or female reproductive systems. However, some organisations have a policy of allowing pregnant women to minimise exposure to monitors during their pregnancy.

There are no Australian Standards or limits set for radiation exposure. The so called ‘Swedish limits’ for computers, designed for measurement and testing of physical emissions, are sometimes used as voluntary recommendations to encourage manufacturers to produce monitors with extremely low emissions. Studies have so far shown only very low to insignificant levels of various radiation emissions.

So-called radiation filters for screens are unnecessary and may degrade the screen image. The best protection operators have from electric field emissions is the screen. It is therefore best that operators are located in front of the screen. The emission of electromagnetic radiation is mainly from the back of the unit and the cabling rather than from the screen. Although this level is low, it is prudent to further minimise any potential risk by ensuring that cables are housed and shielded where possible and personnel are not located closer to the sides or rear of any computer monitor than to the screen of their own unit. Organisations should continue to review information as it becomes available.

Users who remain concerned about the small emission of radiation from conventional screens may prefer to use LCDs.

Laptop users should be advised against the long-term use of the computer on their lap because of possible thermal effects.

In summary, there are claims that the low radiation emissions from CRT screens cause adverse health effects in operators. These claims are not supported by scientific research findings or reliable epidemiological studies at this time. On current evidence, the emissions are considered to pose minimal risk to the health and safety of computer operators.

Guidelines and policies exist aimed at reducing musculoskeletal disorders, and improving the content of work and the work environment. Some of these are incorporated in legislation regarding manual handling, others are developed by employer and employee associations for specific types of work, e.g. call centres. Several Australian Standards refer to the design of furniture, equipment and environments for office work.