Tips on setting up your workstation To promote efficiency and safe& the lighting must be right, desk and chair should be comfortable, and the layout convenient Soectrum staff

In the wave of excitement about purchasing state-of-the-art workstations, it is easy to overlook the ergonomic aspects of the en- gineering environment. But engineers ~ 1 1 1 have to live with workstations day in and day out, so it is important to take the physical layout of both the workspace and the work- station within it intc account if a company wants to maximize the productivity and health of its employees.

IVhile setting up the workstation to avoid eye and muscle fatigue may be the most im- portant aspect of workplace design, what to do about reducing the effect of extremely I O U -frequency (ELF) magnetic fields is the most controversial. The IEEE’s United Stares .ktlvities Board states that, “At the present time [Aug. 13, 19901, there is no coni incing evidence that V h electric and magnetic fields significantly influence the

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health of VDT operators or adversely affect reproductive outcomes among pregnant women. However, further research is need- ed before a more conclusive statement can be made regarding the possible reproductive effects of factors associated with extensive use of VDTs.”

The chief focus of ELF concerns is the workstation monitor, whose under-100-hertz vertical deflection system can generate ELF fields. While magnetic field flux densities of below 1.0 microtesla, as are typical some 30 centimeters from a videodisplay terminal (VDT) screen, are deemed acceptable in Germany and England and by the Interna- tional Radiation Protection Association, no standard for exposure levels has been estab- lished in the United States.

Unverified work done in Scandanavia has led some to suggest that ELF levels be below 0.2 pT. Recent studies of some com- mercial monitors found that field strength, which diminishes with distance, is general- ly below 0.2 pT at 76 cm (about arm’s length) from the monitor’s front and E 2 cm from its sides and back. Responsible monitor manufacturers are beginning to specify ELF levels for their products. In the past, there have been vendors of display “shields” who led buyers to believe their product would re- duce such emissions when it did not.

Since an office partition will not stop ELF

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emissions, workspaces should be set up so that no one in an adjoining area comes within E 2 cm of the sides or back of a monitor in someone else’s work area. (This meets the most stringent guidelines.) For adjoining groups of cubicles, centering a monitor at the back of a typical, 122-by-76-cm desktop and putting desks cattycorner in adjacent corn- ers takes care of this. FENDINSOFF FATIGUE. Engineers will typical- ly want a fairly large display because of the nature of the graphics material-schematic drawings and such-they work with. Some say that a 174x1. diagonal is the minimum ac- ceptable, while others claim they need at least a 19-in. screen. The important thing is that information be easily readable.

The monitor should be situated so that, when the user is looking at it, his or her line of sight is between 10 and 20 degrees below the horizontal. This range seems to be most comfortable for users and helps prevents neck and back strain. Having the ability to tilt the monitor so that the display is perpen- dicular to the line of sight is a plus.

The monitor should also be positioned so that light from overhead fixtures or nearby windows is not reflected by the screen into the user’s eyes. If that’s not possible and the location of overhead lights cannot be changed to prevent reflections, either light baffles or partitions of an appropriate height

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Lighting: angles of more than 60 degrees can cause glare. Use

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should be installed. Similarly, window treat- ments should include adjustable blinds to prevent outside light reflections.

The area around the monitor that the user sees when his or her vision strays from the screen should be at the same luminance as the display to prevent eye strain (caused when the pupil must contract or dilate rapid- ly). Since most users will want to have a reasonably well-lit office, this implies that a predominantly light-colored display (that is, dark characters on a light background) is preferrable; it may also improve both visu- al acuity and depth of field. With a light screen, however, be sure that the scan rate is high enough to prevent flicker. S I T T I M FRETTr. Office chairs should be ad- justable to fit an individual’s physical dimen- sions and provide good back support. A five- footed base is very stable, and casters will make it easier to move around.

At minimum, a desk should allow leg m m 64 cm high, 46 cm deep, and 51 cm wide. For most individuals a surface height be- tween 65 and 75 cm is right for using a key- board or mouse; if a desk is not adjustable in height, then 72 cm is a good compromise. A typical office desk is about 122 cm wide by 76 cm deep. However, if an engineer fre- quently uses large schematics, then the desk should be wider, perhaps as wide as 160 cm. There should also be room for a desk lamp so that reference materials can be lit well. Since there should be a minimum of 46 cm between the edge of the desk and the mon- itor, and since the monitor depth can exceed 30 cm, the desk may have to be deeper than 76 cm or the monitor put on a pedestal or shelf behind the desk.

No matter how comfortable the work- space is, a workstation user should remem- ber to take a rest from screen work occa- sionally; taking five minutes to stretch the limbs and rest the eyes every couple of hours is a good practice. And since workstation use tends to be sedentary, getting in some ex- ercise on the lunchbreak is a good idea. +

Floor plan: corner arrangement inherently prevents extremely Iow- frequency (ELF) emission problems. For facing arrangement, check distance from back of monitor to opposite user.

light baffles or partitlo& to correct lighting problems

Source the Department of Preventive Medicine of the University of Wisconsin the National Research Council, and the National Lighting Bureau

I ’ 37 I Specfrum staff-Tips on setting up your workstation