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A 1990 Macworld article by noted industry critic, Paul Brodeur, proposed that users maintain the following distances to minimize VLF and ELF exposure:
28 inches or more from the video screen
48 inches or more from the sides and backs of any VDTs.
Although these guidelines seem overly cautious, a fundamental principle is that magnetic field strength diminishes rapidly with distance. Users could, for example, select fonts with larger point sizes to permit working farther from the screen. Remember that magnetic fields penetrate walls.
Over-reaction to ELF and VLF radiation can also compromise ergonomics. In a campus computer lab, for example, all displays and keyboards were angled thirty degrees from the front of desktops to reduce the radiation exposure of students behind the machines. The risks of poor working posture in this case appear to be greater than the radiation risks.
A final form of radiation, static electric, can cause discomfort by bombarding the user with ions that attract dust particles, leading to eye and skin irritations. Anti-static pads, increasing humidity, and grounded glare screens are effective remedies for these symptoms.
A continuing process
Massive computerization of offices, laboratories, dormitories, and homes represents a fundamental change in the way many of us work and communicate. It would be surprising if there were no adverse effects from such profound changes. It would also be surprising if all policy debates were based on sound scientific evidence, rather than parochial politics and media exposes. But, as University of Pennsylvania bioengineering professor Kenneth Foster has written, "One difficulty is that 'safety,' if considered to be the absence of increased risk, can never be demonstrated. A hazard can be shown to exist; absence of hazard cannot."
To monitor research and develop institutional guidelines, the University of Pennsylvania has created a Task Force on Computing in the Workplace, with representatives from the Offices of Environmental Health and Safety, Fire and Occupational Safety, Information Systems and Computing, Radiation Safety, Purchasing, University Life as well as staff and faculty from the Wharton School and Schools of Engineering, Medicine and Nursing. Interested readers are welcome to contact the authors for information on the Task Force and its work.
Until more conclusive research becomes available, individuals, departments, and institutions will have to weigh the evidence and make their own decisions about protective measures to minimize the risks of computing. And, in our opinion, the information technology managers and their vendor partners who provided the leadership to computerize our campuses, now owe it to their colleagues to work with epidemiology and ergonomics experts to create computer-intensive environments that are both productive and healthful.
Avoiding carpal tunnel syndrome: A guide for computer keyboard users
Carpal tunnel syndrome (CTS) is a painful, debilitating condition. It involves the median nerve and the flexor tendons that extend from the forearm into the hand through a "tunnel" made up of the wrist bones, or carpals, and the transverse carpal ligament. As you move your hand and fingers, the flexor tendons rub against the sides of the tunnel. This rubbing can cause irritation of the tendons, causing them to swell. When the tendons swell they apply pressure to the median nerve. The result can be tingling, numbness, and eventually debilitating pain.
CTS affects workers in many fields. It is common among draftsmen, meatcutters, secretaries, musicians, assembly-line workers, computer users, automotive repair workers, and many others. CTS can be treated with steroids, anti-inflammatories, or physical therapy, or with surgery to loosen the transverse carpal ligament. Recovery of wrist and hand function is often, but not always, complete.
Causes
Like many skeletomuscular disorders, CTS has a variety of causes. It is most often the result of a combination of factors. Among these are:
Genetic predisposition. Certain people are more likely than others to get CTS. The amount of natural lubrication of the flexor tendons varies from person to person. The less lubrication, the more likely is CTS. One study has related the cross-sectional shape of the wrist, and the associated geometry of the carpal tunnel, to CTS. Certain tunnel geometries are more susceptible to tendon irritation.
Реферат опубликован: 27/01/2008