The AMA’s Misguided Report on Human and Environmental Effects of LED Lighting

Kevin Houser The Pennsylvania State University, Department of Architectural Engineering, University Park, Pennsylvania, USA The American Medical Association (AMA) recently issued a report and recommendations regarding the use of light emitting diode (LED) lighting in outdoor installations [AMA 2016]. The high-level goals of the report are sound and well intended. The report promotes the conversion of outdoor lighting to LED in order to reduce energy consumption and decrease the use of fossil fuels. It also provides recommendations that are intended to reduce glare and minimize the detrimental effects of light on humans and animals. Few would disagree that these considerations are central to high-quality outdoor lighting. Regrettably, AMA’s recommendations are vague and misguided and reflect fundamental misunderstandings of illuminating engineering. The most harmful error is their recommendation to use only sources that have a correlated color temperature (CCT) of 3000 K or lower for outdoor lighting installations. Their recommendation is based on several misunderstandings and false or unsubstantiated assertions. First, there is a frustrating lack of specificity within the AMA report that can only leave the reader to guess what might have been intended. For example, blue light is implicated throughout the document (for example, “excessive blue wavelength” [p. 1], “excessive blue spectrum” [p. 1], “intense blue” [p. 1, 2], “very blue” [p. 2], “blue-rich” [p. 3, 4, 5], “too blue” [p. 5]), yet an operational definition for blue light is not offered. Based on the AMA report, one might reasonably conclude that violet and ultraviolet radiation are of no concern, yet the use of optical radiation shorter than those typically considered “blue” would not be compatible with their goals [see, for example, Barghini and de Medeiros 2012]. What wavelength range is of greatest concern to the AMA? Second, the AMA implies that when a city street is retrofitted with LEDs, a CCT of 4000 K or higher will lead to dissatisfaction, whereas a CCT of 3000 K or lower will be better received. Yet, oddly, even the examples cited by AMA fail to support their claim [CBS Sacramento 2014; Chaban 2015; Sciagliano 2013]. CCT is just one component of lighting quality. An appropriate before-and-after comparison requires measurement of the photometric conditions, including illuminance or luminance of relevant surfaces, spatial uniformity, luminaire luminance, and some characterization of shielding and glare control. Using a source with a CCT of 3000 K will not mitigate complaints associated with poor optics, illuminance levels that are too high or too low, or problems with uniformity. The AMA report argues that discomfort glare is exacerbated by short-wavelength optical radiation that is likely to be more prevalent in high-CCT sources and indeed there is some evidence for that argument. However, that one factor is unlikely to dominate other aspects of LEUKOS, 13:1–2, 2017 Copyright © Illuminating Engineering Society ISSN: 1550-2724 print / 1550-2716 online DOI: 10.1080/15502724.2016.1247566