What is glare?
Glare is related to light sources or surfaces whose luminance and position cause discomfort or reduce the ability to see the task at hand. It can hinder the perception of details, signs, and obstacles, even when the total amount of light seems sufficient. The assessment should consider the person’s field of vision, not just the ceiling installation.
It is useful to distinguish between direct and reflected glare. In the former, the bright source is visible; in the latter, its image or glare appears on another surface. Both situations can coexist and vary depending on posture, time of day, or the material being worked on.
Sources and common situations
A very bright window directly in front of you, a light fixture without adequate protection, or a poorly positioned task lamp can all cause direct glare. Reflections can appear on screens, documents protected by plastic, tables, tools, or polished surfaces. Changing the finish of an object can alleviate the problem without changing the lighting.
The person’s position is crucial. A source that doesn’t bother someone inspecting the workstation while standing may be within the field of vision of someone working while seated or bent over. Therefore, it’s advisable to observe the actual activity, including adjustments, instrument readings, movements, and less frequent tasks.
Quantity of light and visual quality
Illuminance describes the light that reaches a surface and is usually expressed in lux. Luminance helps describe how bright a source or surface appears in a particular direction. These are different quantities: having a sufficient level of illumination does not guarantee comfortable visual distribution or the absence of glare.
Workstation lighting must also consider uniformity, contrast, shadows, and transitions between areas. Increasing power without checking orientation and distribution can worsen the problem. Reducing all light to eliminate a glare can leave other tasks insufficiently illuminated. The solution needs to balance the demands of the entire job.
Evaluation under real-world conditions
The review identifies visible light sources, reflective surfaces, and work positions. People are asked when the difficulty occurs, and variations in natural light are observed. A visit during a single time period may not detect glare that occurs with different sun positions.
Measurements and evaluation methods must be appropriate to the objective. A single lux value does not demonstrate the absence of glare. It is advisable to document the task, gaze direction, lighting configuration, and observed conditions. If technical design indices are used, they must be applied within their scope and with the necessary data.
Screens and workstation adaptation
When working with screens, their placement relative to windows and light fixtures helps avoid glare and high contrast. The orientation and settings of the equipment, the simultaneous reading of documents, and the surrounding environment should also be considered. Adjusting the brightness doesn’t always solve a problem caused by the workstation layout.
When a person constantly bends or twists to avoid a glare, awkward postures can develop. The assessment should integrate both aspects. The solution should allow the person to see and work in a comfortable position, without requiring constant bodily compensation to overcome poorly designed lighting.
Control measures
Measures may include rearranging workstations and light fixtures, directing task lighting, installing appropriate shielding for light sources, and controlling natural light entry with adjustable systems. Matte finishes and surface selection can reduce glare when compatible with the task and its technical requirements.
Royal Decree 486/1997 requires the avoidance of direct and indirect glare within its scope. For equipment with screens, Royal Decree 488/1997 adds specific coordination requirements between workstation and lighting. The solution must maintain sufficient illumination and not interfere with traffic routes, signs, or safety conditions.
Practical example
At an inspection station, a new light fixture improves document readability but creates a harsh glare on a metal part. The person begins to bend down to check the finish. A lux measurement on the table provides a sufficient reading, although the visual task remains difficult.
The review tests different light orientations and distributions, along with compatible changes to the workpiece support. The entire inspection is verified with various finishes and positions. It is also noted whether the compensating tilt disappears. The success criteria combine visibility, posture, and safety, rather than simply achieving a specific illuminance level.
Monitoring and common errors
Common mistakes include addressing every complaint by increasing power, evaluating from a different vantage point than the work area, and assuming everyone sees the same. Another mistake is installing a screen or changing furniture without considering the new relationship with windows and light sources.
Monitoring should include facility maintenance and cleaning, layout changes, and new tasks. User observations provide information on variations that a single measurement might not capture. The evaluation is enhanced when it connects visual quality with the ergonomic design of the workstation and verifies solutions during actual work.
