AMA Report Stirs LED Lighting Controversy
11/5/2016 9:13 AM
In recent years, municipalities around the world have begun swapping out existing street lamps for more energy efficient varieties. The new, primarily LED-based lighting looks different – it tends to be whiter and “glarier” than its mellower, sodium-based predecessor. Coincidentally, this initiative is taking place at the same time that on a research level, much is being discovered about the effects of light on human – and animal – health. Exposure to blue light in particular at night has been linked to a number of maladies, from poor sleep to greater chances of developing certain cancers. Since light is light, whether it comes from a street lamp or a glowing screen, displays are also a crucial part of this light/health balance.
A lighting “conversation” among various organizations began last summer, when the American Medical Association issued a report titled “Human and Environmental Effects of Light Emitting Diode (LED) Community Lighting,” in which the authors recommended the conversion of conventional street lighting to LED-based lighting. Additional recommendations included “the use of 3000K [as measured in correlated color temperature or CCT] or lower lighting for outdoor installations such as roadways,” proper shielding, and the reduction of blue-light emissions to the greatest extent possible.
Numerous publications picked up the report, streamlining and adjusting the main message as primarily anti-LED. A representative piece from CNN carried the headline, “Doctors issue warning about LED street lights.” In turn, agencies such as the Office of Energy Efficiency and Renewable Energy (OEERC) and the Lighting Research Center (LRC) at Rensselaer Polytechnic Institute issued statements of their own.
From the OEERC: “Some media coverage of concerns about blue light, light at night, and dark-sky issues can give the impression that LEDs are the enemy, when in fact they're a critical part of the solution, which the AMA acknowledges. It's important to remember that these issues have been around for decades, long before the emergence of LED technology.”
The LRC issued an eight-page response to the AMA report as well as a press release with the following bullet points:
-Predictions of health consequences from light exposure depend upon an accurate characterization of the physical stimulus as well as the biological response to that stimulus. Without fully defining both the stimulus and the response, nothing meaningful can be stated about the health effects of any light source.
-Notwithstanding certain sub-populations that deserve special attention, blue light hazard from In-Ga-N LEDs is probably not a concern to the majority of the population in most lighting applications due to human’s natural photophobic response.
-Both disability glare and discomfort glare are mostly determined by the amount and distribution of light entering the eye, not its spectral content.
-In-Ga-N LED sources dominated by short wavelengths have greater potential for suppressing the hormone melatonin at night than sodium-based sources commonly used outdoors. However, the amount and the duration of exposure need to be specified before it can be stated that In-Ga-N LED sources affect melatonin suppression at night.
-Until more is known about the effects of long-wavelength light exposure (amount, spectrum, duration) on circadian disruption, it is inappropriate to single out short-wavelength radiation from In-Ga-N LED sources as a causative factor in modern maladies.
-Correlated color temperature (CCT) is not appropriate for characterizing the potential impacts of a light source on human health because the CCT metric is independent of nearly all of the important factors associated with light exposure, namely, its amount, duration, and timing.
For additional feedback and analysis, Information Display checked in with Jennifer A. Veitch, Principal Research Officer at the National Research Council of Canada and Director of Division 3 (Interior Environment and Lighting Design) of the International Commission on Illumination (CIE). Veitch authored the article “Light for Life: Emerging Opportunities and Challenges for Using Light to Influence Well-Being” for the November/December 2015 issue of ID.
Veitch said she agrees with the LRC’s response: “LEDs are not intrinsically more harmful to humans than other types of lighting, though they do have the potential of being harmful,” she says. She also noted that CCT is a poor indicator of a spectrum’s exact wavelength. “It’s a useful metric,” she added, “but simply to say that all lighting more than 4000K is harmful is wrong.”
ID asked Veitch if LEDs might be particularly suspect because people don’t find them aesthetically pleasing. She replied: “As with most lighting installations, it’s not the fault of the light source. It’s in the way that you apply it.” And, she noted that people tend not to be comfortable with new types of light sources. (Interestingly, the “warm” yellow glow of the sodium lights most of us consider normal dates back only as far as the 1970s and 1980s, when the older, and much whiter, mercury vapor lamps introduced in the late 1940s began to be phased out. The sodium lights were unpopular at first too.
One reason why LED lighting strikes so many people as harsh is that it’s not being used to its best advantage. For financial and logistical reasons, towns and cities want to keep the existing physical infrastructure for lighting – the same number of poles spaced the same way, at the same height, etc. -- and this arrangement often doesn’t employ the new lighting technology to its best effect. “There are a number of products out there that are quite glary, but that has nothing to do with the spectrum,” said Veitch. “Any misapplied light source will give a bad outcome.” Veitch also made the point that LEDs are more controllable that previous light sources – they can be dimmed.
The important thing to keep in mind, she said, and this affects display makers and users as much as city planners, is that what counts is the lighting we’re exposed to before we go to bed, not its source. “Your body doesn’t care what the source is,” said Veitch, adding, “Of course, with street lighting, is it’s not only people who are affected but animals.” With the research – and the controversy – continuing, it’s a pretty sure bet that in years to come, we’ll find ourselves looking more carefully at the light we expose ourselves to, especially that from laptops, televisions, and smartphones – particularly before we go to bed. ---Jenny Donelan