Thomas Edison’s brilliant 1879 invention — the incandescent lamp — has transformed the way we live and work in the industrialized world. As with any major innovation, however, there have been risks as well as benefits to artificial lighting. From a health and safety standpoint, workplace lighting presents two major areas of concern. The most obvious is visibility, including all those factors that affect our ability to see clearly and comfortably in any work situation. The second pertains to artificial lighting’s invisible hazards: the possible link to skin cancer from exposure to fluorescent lights emitting ultra-violet (UV) rays; and increased incidence of breast cancer from exposure to light at night experienced by women working night shifts.
The first section focuses on visibility issues, while the latter part is devoted to related cancer concerns.
What are the health effects of poor lighting?
Inferior lighting can cause numerous health problems. Below are some lighting problems commonly encountered in workplaces and their associated outcomes.
Insufficient light can result from too little illumination from fixtures and low reflective levels from ceilings and walls. But the question of how much light is enough depends on the task at hand. The Illuminating Engineering Society Lighting Handbook provides extensive tables listing recommended lighting levels for a variety of activities. For instance, they recommend 3000 lux for precise assembly work, 7500 lux for very precise machine tool work, and 750 lux for general office work. Regardless, insufficient light prevents workers from seeing details, which can cause accidents, eyestrain, headaches, and musculoskeletal problems from adopting a poor posture to compensate for inadequate light.
Excessive light can also be hazardous. More is certainly not always better, especially for office or computer workers. The results of one study of open-plan offices showed that very high levels of lighting increased the risk of troublesome reflections, deep shadows, and excessive contrast causing eyestrain, eye irritation, and associated headaches and fatigue. Too much direct or reflected light within the field of vision can also result in direct or indirect glare. A review of the physical layout of a workplace should ensure that lights are not placed directly in any worker’s line of vision. Indirect glare is a common glare problem experienced by indoor workers. Over time it can cause deterioration of vision. Poor posture and resulting musculoskeletal injuries are also a problem when it comes to glare, as workers will adjust their posture to avoid glare.
Incandescent lamps are the modern version of Thomas Edison’s original light bulb. They require a lot of electricity and, at the same time, produce a great deal of heat. Halogen lamps are a type of incandescent light offering intense and consistent light levels to work areas.
Fluorescent lighting: The chief appeal of this lighting is its low cost. Fluorescent tubes that are old or defective often develop a slow, visible flicker, which causes visual discomfort. They must be replaced according to manufacturer specifications. Since most fluorescent lights also contain toxic materials, like mercury, disposal is also an issue.
Full spectrum light is one type of fluorescent lighting. Nonetheless it seems to address many workplace illumination problems. It reportedly increases visual perception, reduces eyestrain, and relieves headaches and fatigue. Full spectrum, as the name implies, is also said to imitate the benefits of natural light, reportedly causing the body to produce neurochemicals for stress regulation. One U.S. company also reported that after installing full spectrum lighting in its computer operation, the error rate of the department fell significantly. Worker productivity and satisfaction also increased.
What about the links between cancer and lighting?
There is strong scientific evidence that supports a relationship between malignant melanoma and other skin cancers and exposure to ultraviolet (UV) radiation. Although most of these studies focus on UV rays from the sun, there are many non-solar sources — including fluorescent lighting — which emit radiation in the various UV ranges, particularly the UVB class (characterized by wavelengths from 280 to 320 nanometers in the electromagnetic spectrum).
UVB light is known to alter DNA sequences and gene expression, and has been found in animal experiments to be the most effective in inducing skin cancers of both the melanoma and non-melanoma types. Some annual workplace exposures in the UVB range from fluorescent lighting have been reported to exceed annual solar exposures of outdoor workers.
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