Jul 11, 2017

Research shows that we urgently need improved lighting in industrial environments
By Willard Warren

The enthusiastic adoption of LEDs and ever-stricter energy codes are moving us closer to achieving lower lighting power densities in buildings, but there are issues of health and safety that must be dealt with. One is the disruption of circadian rhythms which was covered in several sessions at the recent LIGHTFAIR International conference in May. Another is that the cause of death given in many obituaries is “after a fall.” The concern is that many falls are self-inflicted. Many are the result of aging, where the reduction in our field of view and the opening of our irises limits our peripheral vision. Consequently, our autonomic nervous system cannot protect us as well from hazards off the line of sight.

The effects of poor surround lighting and the lack of corrective lenses being worn by workers who need them are also putting us in danger. This subject was covered in an article in the May issue of the IEEE Industry Applications Magazine entitled “Lighting Matters in Industrial Environments: A Framework Linking Workplace Safety to Lighting Quality Metrics.” The authors reviewed the literature on the subject of occupational hazards and found that the U.S. Department of Health and Human Services is on record saying that “Human error is identified as the primary or contributory cause of approximately 85 percent of industrial accidents.”

According to the article, the U.S. Bureau of Labor Statistics reported that “People 45 years of age are above average in incurring accidents, and those over 65 have the highest incidence of them.” They also reported that “The quality of lighting can have a positive impact on reducing the risk of the primary causes of occupational injuries.”

The article authors, who are knowledgeable lighting people with Chevron and Crouse-Hinds, did a survey of factory workers and learned that 45 percent of workers under 50 years of age wear glasses, but only 50 percent of those over 50 wear them. (Editor’s Note: That’s way too small an increase for safety’s sake.) They also found that few workers over 50 believe that lighting plays an important role in safety and performance, but worse, 17 percent of senior workers who drive vehicles in the factory admit that at the speed they normally go it’s very difficult to stop in time to avoid collisions.

According to the survey, only 30 to 40 percent of workers feel that their plant lighting is satisfactory. It would seem then that there is a self-inflicted component involved in worker injuries and that we must provide better surround lighting in factories. We also must require that workers who need corrective lenses wear them.

In offices, self-illuminated screens on computer monitors have become brighter and more comfortable, but the issues of visual errors and glare remain, especially from sunlight. We know from experience that the headlights of oncoming cars and streetlights that are left on during the day are no problem because in daytime we adapt to high volumetric brightness, but at night, those same light sources can be blinding. As we introduce more daylight into office interiors, drawing the shades just eliminates the daylight harvesting we need for load reduction, so we must shield ourselves from sunlight and brighten up the walls and other surfaces to increase our adaptation level. It wouldn’t surprise me if some office workers don’t wear the corrective lenses that they need to see well, just like our factory workers.


Willard Warren

Willard Warren

Willard L. Warren, PE, LC, Fellow IES, DSA, is principal of Willard L. Warren... More info »