Ergonomics usually brings to mind desks, keyboards and chairs. But proper lighting is also a critical part of ergonomics and is a factor in virtually every workplace. Its effects on workers and workplaces can be far-reaching and poor lighting can have an adverse effect on productivity, job performance, job satisfaction and the physical health of workers. Given that people receive 90% of their information visually, this is hardly surprising. Eye strain, eye irritation, blurred vision and headaches are some of the common ailments associated with poor lighting. It can also cause people to lean forward or back in order to see better, creating awkward body postures that can contribute to musculoskeletal and other physical ailments. (Learn more in 10 Important Ergonomic Aids for Office Workers).
But good lighting can also go a long way to improving accuracy and reducing injuries due to accidents. It is even a positive influence on mood which in turn has positive effects on productivity, performance, satisfaction and even physical wellness.
There are several issues related to lighting that can impact its effects on workers including lighting types and sources, colours and distribution (fixtures). (Learn more in Lighting Ergonomics 101).
Types of Lighting
There are three basic types of lighting and each are used for very specific tasks. Natural lighting can be considered a fourth, but it has some limitations. Daylight, like that provided through windows, can provide excellent illumination but weather, time of day and even the location of a window mean that its quality and consistency vary widely. Instead, most commercial operations rely on general, localized-general and local lighting for illuminating workspaces.
General lighting provides uniform illumination across an area. Ceiling fixtures that light up a large area like a warehouse or office are an example of this type of lighting.
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Localized-General lighting combines general lighting with overhead fixtures that deliver additional localized lighting to specific areas, a packing table or work area for example.
Local lighting, also known as task lighting, is designed to illuminate a relatively small area and a specific task. An example of this might be a flexible desk lamp. Local lighting also affords some flexibility and the power to adjust the lighting to the user. This control allows the individual user to adjust for maximum vision and reduction of eye strain.
There are two general sources of light — daylight and electric light. Again, daylight is an excellent source of light as it is not overly bright and does not normally cause glare on surfaces. However, daylight is affected by the number, position, and size of windows in a building and also by the presence of window coverings. Because of these factors, along with daylight’s general lack of consistency, most commercial operations also rely on electric lights.
The strength, colour and usability of electric lighting is dependent on the type of bulb that is used. Different types of bulbs are more suitable to specific types of workplaces due to both their efficiency and colour rendering – the effect the light has on the colour of objects. Incandescent bulbs although generally a good source of light, are seldom used in workspaces due to their low efficiency. Most offices will use fluorescent and mercury bulbs. Factories and commercial enterprises will commonly use high-pressure sodium, mercury, and metal halide bulbs.
Lighting distribution refers to the way in which light fixtures distribute light. Light fixtures, also known as luminaires, are used to control light distribution and there are four main types, all of which distribute light in different ways.
- Direct Light Fixtures project most of their light downward, creating a well-lit workspace but they also tend to create shadows.
- Direct-Indirect Light Fixtures project light both downward and upward. They will also reflect light off the ceiling and walls and can reduce glare because they emit no horizontal light.
- Indirect Light Fixtures project the majority of their light upward, so ceilings must be reflective. Generally, they provide the least amount of exposure to glare and the most even type of lighting.
- Shielded Fixtures use shields in the form of diffusers, lenses, or louvers to distribute light in specific ways.
- Diffusers are translucent glass or plastic covers used on the bottom and sides of lights.
- Glass or plastic lenses use prisms and flutes to distribute light.
- Louvers are essentially baffles that shield the bulb and direct light to distribute it evenly and decrease brightness.
Colour and Strength
All light has some colour and specific colours make it easier to see and can also reduce eye strain. Lighting that is yellow rather than white or blue in tone tends to be easier on the eyes and unlike the blue tones of computer screens and related devices, it doesn’t cause problems with Circadian rhythms and sleep. Lighting can also be adjusted, either automatically or manually, to brighten or dim according to the time of day and coverings for lights now exist that can, for example, change the colour of fluorescent lights.
Keys For Ideal Ergonomic Lighting
The best choices for ergonomic lighting depends on the nature of the work being done and the characteristics of the work pace itself, but there are some best practices for ergonomic lighting that are common to all workplaces. Ergonomic lighting should always:
- Ensure sufficient lighting
Strike a balance. Lighting should be adequate for the work being done. Both too much light and too little light can cause eye strain, irritation and headaches and make it much more difficult to see.
- Reduce shadows
Dark spaces in a workplace can contribute to eye strain as workers adapt their eyes to see; they can also cause accidents. Suppress the flickering light that often accompanies fluorescent lighting with filters and covers. Strategic positioning and the height of lights can help reduce shadows.
- Eliminate glare
Glare occurs when a bright light or reflection causes part of an object to be much lighter than other parts. Eyes generally adjust to the brightest light making it much more difficult to see the darker areas. Glare can be reduced by using matte rather than glossy paint, increasing the brightness of the area around the glare, diffusing light sources with louvers or lenses and by proper positioning of light fixtures.
- Ensure adequate contrast
Issues related to inadequate contrast occur when there are different lighting levels between areas in a workplace or there is a lack of contrast between the colours of objects as, for example when a written text and the paper it is printed on are too similar in colour. Both can be distracting to workers and cause productivity, health and safety issues. Reducing glare, increasing lighting in work areas rather than in the surrounding area, using contrasting colours for machinery parts can all increase contrast and increase visibility.
Good ergonomic lighting is relatively easy to achieve and can have a positive impact on worker health and productivity.