Strong arguments exist for overhauling the lighting systems on U.S. roadways with light emitting diodes (LED), but conversions to improper LED technology can have adverse consequences. In response, physicians at the Annual Meeting of the American Medical Association (AMA) adopted guidance for communities on selecting among LED lighting options to minimize potential harmful human and environmental effects.
Converting conventional street light to energy efficient LED lighting leads to cost and energy savings, and a lower reliance on fossil-based fuels. Approximately 10 percent of existing U.S. street lighting has been converted to solid state LED technology, with efforts underway to accelerate this conversion.
"Despite the energy efficiency benefits, some LED lights are harmful when used as street lighting," AMA Board Member Maya A. Babu, M.D., M.B.A. "The new AMA guidance encourages proper attention to optimal design and engineering features when converting to LED lighting that minimize detrimental health and environmental effects."
The National Electrical Manufacturers Association (NEMA) issued the following comments regarding the AMA guidance: “NEMA is a long-time proponent of good quality lighting design and application with technical standards and guidance for manufacturers and their end-use customers. The American Medical Association's community guidance on LED outdoor lighting is aligned with lighting manufacturers' long-standing recommendations on how to design safe and efficient light for night, including: Using lighting control options such as motion or dusk-to-dawn sensors; Shielding the light source to curtail excessive uplight, sidelight, and glare; Designing for the minimum light levels and energy necessary for the task .
“NEMA and its lighting manufacturer Members support the proper application of light at the right placement, right time and in the right amount. NEMA Members actively assist installers and customers with the best application and maintenance of their products. Consequently, there are few technical reasons or limitations to stand in the way of preventing misdirected light and glare. NEMA Member products are readily available for a wide array of solutions.
“The AMA makes further recommendations regarding the spectral content of outdoor lighting installations that raise serious concerns for electrical manufacturers. NEMA agrees that spectral content should be one factor in effective lighting for outdoor installations. However, a single solution is simply not appropriate for all situations. NEMA also questions the wisdom of assigning significant weight to this recommendation since outdoor lighting design requires a complex analysis of many criteria. Outdoor lighting systems will vary depending on the application and local conditions. Tradeoffs in the considerations of visibility, environmental impacts, energy efficiency, cost, personal safety and security need to be optimized, which cannot be achieved with a single solution.
“The AMA recommendation encouraging the use of 3000K correlated color temperature (CCT) or lower may compromise the ability of the lighting system to meet all critical design criteria for each unique application. As indicated by the U.S. Department of Energy (DOE) in its June 21, 2016, statement, CCT does not explicitly characterize the potential for nonvisual effects, which also depend on quantity and duration of exposure to light. The DOE further clarifies than an LED light source with the same CCT as a non-LED source has about the same amount of blue spectral content. The AMA recommendation for 3000K or lower is not an appropriate solution for all applications, nor is it is supported by the current body of research. NEMA will issue additional technical guidance specific to the issues and tradeoffs related to the spectral content of lighting solutions.â€
The AMA guidance continued: High-intensity LED lighting designs emit a large amount of blue light that appears white to the naked eye and create worse nighttime glare than conventional lighting. Discomfort and disability from intense, blue-rich LED lighting can decrease visual acuity and safety, resulting in concerns and creating a road hazard.
In addition to its impact on drivers, blue-rich LED streetlights operate at a wavelength that most adversely suppresses melatonin during night. It is estimated that white LED lamps have five times greater impact on circadian sleep rhythms than conventional street lamps. Recent large surveys found that brighter residential nighttime lighting is associated with reduced sleep times, dissatisfaction with sleep quality, excessive sleepiness, impaired daytime functioning and obesity.
The detrimental effects of high-intensity LED lighting are not limited to humans. Excessive outdoor lighting disrupts many species that need a dark environment. For instance, poorly designed LED lighting disorients some bird, insect, turtle and fish species, and U.S. national parks have adopted optimal lighting designs and practices that minimize the effects of light pollution on the environment.
Recognizing the detrimental effects of poorly-designed, high-intensity LED lighting, the AMA encourages communities to minimize and control blue-rich environmental lighting by using the lowest emission of blue light possible to reduce glare. The AMA recommends an intensity threshold for optimal LED lighting that minimizes blue-rich light. The AMA also recommends all LED lighting should be properly shielded to minimize glare and detrimental human health and environmental effects, and consideration should be given to utilize the ability of LED lighting to be dimmed for off-peak time periods.
