Step-by-Step Ergonomics Design R

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Work Station Visual Environment Guidelines

Workstation Visual Environment Guidelines

The visual environment includes those factors that affect vision: specifically, illumination, glare, and color. Each factor can have an impact on human performance and comfort.

Illumination
Glare

Illumination

Type of Activity or Area	Range of Illuminance
Type of Activity or Area	Lux	Foot-candles
Public areas with dark surroundings.	20-50	2-5
Simple orientation for short temporary visits.	> 50-100	> 5-9
Working spaces where visual tasks are only occasionally performed.	> 100-200	> 9-19
Visual tasks of high contrast or large size: reading printed material, typed originals, handwriting in ink, good xerography; rough bench and machine work; ordinary inspection; rough assembly.	> 200-500	> 19-46
Visual tasks of medium contrast or small size: reading pencil, poorly printed or reproduced material; medium bench and machine work; difficult inspection; medium assembly.	>500-1,000	> 46-93
Visual tasks of low contrast or very small size: reading handwriting in hard pencil on poor quality paper, very poorly reproduced material; very difficult inspection.	> 1,000-2,000	> 93-186
Visual tasks of low contrast and very small size over a prolonged period: fine assembly, high difficult inspection, fine bench and machine work.	> 2000-5000	> 186-464
Very long and exacting visual tasks: the most difficult inspection, extra fine bench and machine work, extra fine assembly.	> 5000-10000	> 464-929
Very special visual tasks of extremely low contrast and small size.	> 10000-20000	> 929-1858

Glare

Figure below illustrates the direct and indirect glare zones for an operator; the direct glare zone is the region described by a 45° arc above the line of vision, while the indirect glare zone is the working surface.

Illustration of direct and indirect glare zones

Recommendations for Controlling Glare

Position lighting units as far away from the operator's line of sight that is practical.

Use several low-intensity lighting sources rather than one bright one.

Use lighting sources that produce a batwing light distribution, and position workers so that the highest light levels come from the sides, not the front and back.

Use lighting with louvers and prismatic lenses.

Use indirect lighting.

Use light shields, hoods, and visors at the workplace if other methods are impractical.

Avoid placing lighting units in the indirect glare offending zone.

Use lighting with diffusing or polarizing lenses.

Change the orientation of the workplace task, viewing angle, or viewing direction until the maximum visibility is achieved.

Use surfaces that diffuse light, such as flat paint, non-gloss paper, and textured finishes.

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