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1995-01-22
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INFORMATION DATE 19930217
DESCRIPTION USDOL Program Highlights, Safety with Video Display
Terminals
TOPIC Video Display Terminals
SUBJECT Safety with Video Display Terminals
ABSTRACT Possible safety and health problems associated with
video display terminals (VDTs). Some concerns include
high voltage electricity, ergonomics, and noise;
whether extreme low frequency fields or higher
frequency radiation fields emitted by VDTs pose any
problem, particularly for pregnant women.
U.S. Department of Labor
Program Highlights
_________________________________________________________________
Fact Sheet No. OSHA 92-24
SAFETY WITH VIDEO DISPLAY TERMINALS
The Occupational Safety and Health Administration (OSHA) is
often asked about possible safety and health problems associated
with video display terminals (VDTs). Some concerns include high
voltage electricity, ergonomics, and noise. But the greatest
interest is in whether extreme low frequency fields or higher
frequency radiation fields emitted by VDTs pose any problem,
particularly for pregnant women.
OSHA has no standards that apply specifically to video
display terminals or to extreme low frequency electric and
magnetic field exposure. However, OSHA does have standards to
protect employees against overexposures to radiation, noise, and
electrical hazards.
RADIATION: The National Institute for Occupational Safety and
Health (NIOSH), the U.S. Army Environmental Hygiene Agency, and
others have measured radiation emitted by VDTs. The tests show
that levels for all types of radiation are below those allowed in
current standards. In fact, some measurements show radiation
levels so low that they cannot be distinguished from general
environmental radiation (background radiation).
Currently, OSHA has no reliable information that any birth
defect has ever resulted from a pregnant woman working at a video
display terminal. However, the possible effects of radiation or
extreme low frequency fields from VDTs on pregnancies continue to
concern employees. Therefore, NIOSH and others are currently
conducting major studies to thoroughly investigate any potential
problems.
NOISE AND ELECTRICAL HAZARDS: It is unlikely that noise
exposures in a typical office setting, even in an office with a
pool of VDTs, would exceed OSHA standards. However, a cluster of
high-speed printers without sound screens could produce some
questionable noise levels.
Noise levels should be kept within comfortable limits.
Sound sources that are unacceptably noisy should be shielded by
sound absorbent screens or hoods or placed in a separate room.
Absorbent materials such as acoustical ceiling tile, carpets,
curtains, and upholstery also can cut noise.
OSHA has a number of electrical requirements applicable to
VDTs. The equipment must be properly installed, used, and
grounded to ensure employee safety.
PHYSICAL DISCOMFORTS: Video display operators sometimes report
eye fatigue and irritation, blurred vision, headaches, dizziness,
and pain or stiffness in the neck, shoulders, back, arms, wrists,
and hands. These problems usually can be corrected by adjusting
the physical and environmental setting where the VDT users work.
The relation of the operator to the keyboard and the screen, the
operator's posture, the lighting, and the background noise should
be carefully examined to prevent discomfort.
LIGHTING: Work stations and lighting should be arranged to avoid
reflections on the screen or surrounding surfaces. Light should
be directed so that it does not shine into the operator's eyes
when the operator is looking at the screen.
Normal office lighting can be supplemented by individual
"task lighting" at a work station if necessary. Task lighting
enables operators to adjust lighting to their individual
preferences.
GLARE: Glare can result from light reflecting on a VDT screen or
shiny keyboard. Anti-reflective screen treatment can be added to
a VDT screen, and later model keyboards usually have an anti-glare
matte finish. To avoid glare, display screens may be
placed near a window so the line of sight between eye and screen
is parallel to the window surface or the windows can be shielded
to reduce excessive sunlight. Walls painted with a nonreflective
medium-to-dark paint can minimize glare.
WORK STATION DESIGN: An individual work station should provide
the operator with a comfortable sitting position sufficiently
flexible to reach, use, and observe the screen, keyboard, and
document. Some general guidelines to minimize fatigue include:
Posture support: The seat and backrest of the chair should
support a comfortable posture permitting occasional
variations in the sitting position. Chair height and
backrest angle should be easily adjustable. A foot rest may
be necessary for short individuals.
Arms: When the operator's hands are resting on the
keyboard, the upper arm and forearm should form a right
angle. The hands should be in a reasonably straight line
with the forearm. Long or unusually high reaches should be
avoided. Armrests should permit periodic support as needed.
Legs and feet: The chair height is correct when the entire
sole of the foot can rest on the floor or footrest and the
back of the knee is slightly higher than the seat of the
chair. This allows the blood to circulate freely in the
legs and feet.
Adjustment of screen position: Screens which swivel
horizontally and tilt or elevate vertically enable the
operator to select the optimum viewing angle.
Work station surface: The table or work station should suit
the kind of task to be done. It should be large enough for
any reference books, files, telephone, or text and also
permit different positions of the screen and keyboard.
Adjustable surface height is an advantage.
Eye and screen: The topmost line of the display should not
be higher than the user's eyes. The screen and document
holder should be the same distance from the eye (to avoid
constant changes of focus) and close together so the
operator can look from one to the other without excessive
movement of the neck or back. The incline of the document
holder should be adjustable. Legibility is a prime
consideration in selecting a display screen. This also
applies to document selection. Legibility factors to be
considered include: symbol size and design, contrast, and
sharpness.
Adjustment of the keyboard: A movable keyboard is a plus.
It can be arranged to suit the type of work and the need to
consult documents or notes.
TASK CONSIDERATIONS: The type of task performed on a VDT
influences the development of fatigue. Therefore, in designing a
work station, the type of tasks a worker does should be
considered when placing the screen and keyboard. Whatever the
task, it is desirable for the operator to have some "job
control" -- the opportunity to pace the work, add mini-breaks, or
change positions.
________________________________________________________________
This is one of a series of fact sheets highlighting U.S. Department
of Labor programs. It is intended as a general description
only and does not carry the force of legal opinion.