10 minute read
Unsafe at a Million Candela
By JAMES R. BENYA, PE, FIES, FIALD
In the late 1990s, I spoke at an environmental conference in San Diego. My principal message in those days was energy efficiency and environmental responsibility, and my special interest, preventing outdoor light pollution. I made my message as mainstream as possible, which to me meant gaining the willing participation of lighting manufacturers, government agencies, utility companies, design professionals, electricians and contractors, and everyday people towards a common goal of dramatically reduced environmental impacts and better lighting quality.
Yes, it would take a revolution at all levels, but after all, the alternatives were really bad.
At that conference, I met Ralph Nader. A lawyer and perennial presidential candidate, he became famous for his 1965 book Unsafe at Any Speed that criticized the American auto industry in general for its unsafe products. He attacked General Motors’ (GM’s) Corvair automobile, in particular.1 His book became a best seller and led directly to the passage of the 1966 National Traffic and Motor Vehicle Safety Act, which gave the government the power to enact safety standards for all automobiles sold in the United States.
Now, Ralph is a Don Quixote-type character, perennially tilting towards the left side of the environment and politics with little concern for himself. At the time, I could not imagine a future in the lighting industry that would struggle in the same way with obvious conflict between fabulous technology and a growing amount of conflicting science.
But the early 2000s brought profound changes in lighting theory, technology and applications. On parallel courses were LED technology and the so-called human-centric lighting (HCL) movement. In 2002, when LED technology was in its infancy, Dr. Roland Haitz predicted that within 2 decades, solid state lighting would be twice as efficient as the best available at the time.
The “Haitz curve” proved to be conservative, and with the enormous support of industry and our national laboratories, the energy efficiency of lighting is no longer a significant issue. The superiority of LED lighting is unquestionable in almost every metric of energy efficiency, convenience, cost effectiveness, color rendering, and flexibility. Zero to 100 percent in only 20 years is nothing short of phenomenal.
So, as we work today, the success of LED lighting must be counted among the most important inventions in history.
About the same time, human-centric lighting (“HCL”) theory emerged. It was born of an industry needing something beyond energy efficiency. At first there was a lot of snake oil selling of bluish fluorescent lamps to unwitting customers, but after a while, legitimate research concerning human health related to light exposure and its impact on the circadian rhythm showed up.
It took a decade, but ultimately the quackery disappeared, and today, serious science has prevailed. A good example is the work of the Light & Health Research Center with considerable credit to its lead professor, Dr. Mariana Figueiro, and the LHRC’s role in the Department of Population Health Science & Policy at the Icahn School of Medicine at Mount Sinai. Yes, spectrum, exposure and timing matter. Inclusion in the WELL standard further legitimizes the principles that the architecture and engineering professions will now at least consider on all projects.
That said, I think there is still a lot to study and understand. LED lighting technology has changed everything. And not all of it is good.
In our haste to save energy and achieve all the exciting capabilities of LEDs, we have overlooked the shortcomings. Aside from the circadian and wellness issues, some time ago scientists found that flicker, glare, and other extremes in certain lighting applications were problematic, especially for those persons suffering from lupus and other neurological issues.
For example, we are and have been aware that exposure to extremely bright sources or bright sources that rapidly changed intensity, spectrum and/or direction could impact some humans in very negative ways, which the Cleveland Clinic describes as photophobia.2 Your eyes’ sensitivity to light, especially bright light, can cause discomfort and even pain.
That’s exactly what some LEDs do; they can be extremely bright, rapidly change intensity and spectrum, and move or chase. Digital video billboards are an extreme example, and so are some types of spotlights used in theaters and night clubs.
Two decades ago, I was first introduced to the challenges of re-lighting a home in Palm Springs in which the homeowner’s wife suffered from extreme light sensitivity, and given the limits of available science at the time, I worked with the client on control of luminance, intensity, modulation and spectrum until we found a combination that she found no longer affected her. For that project I prioritized indirect incandescent lighting, and it worked. The experience taught me to consider the flicker and spectrum as well as the intensity of the visible source.
Then along came LEDs. Looking back, maybe I should have seen the warning flags of certain characteristics of LEDs. In fact, last issue, I wrote about the work of Pacific Northwest National Laboratories (PNNL) and work on flicker for which Naomi Miller was, in part, awarded the 2024 IES Medal. The truth here is really simple: standard LED dimming causes flicker.
From an electrical engineering perspective, to achieve dimming of LEDs, it is not practical to reduce the voltage as the LEDs must be turned on and off, with the ratio of “on time” to “off time” determining apparent brightness. Now, with incandescent lamps, this works fine. The persistence of the incandescent filament means that the filament will continue to glow once the voltage is removed, which eliminates flicker, and turning lamps on and off 120 times per second is essentially flicker-free. But LEDs have no persistence. The LED will appear to dim, and flicker is both the cause and effect.
As PNNL documented, human problems with it are minimized when the dimming frequency is very high (35-50 kilohertz or more). But high frequency operation must be confined to a small area or volume and enclosed in metalized shield to mitigate radio frequency interference (RFI), which in many applications can defeat the desirability of LED as a light source.
In other words, almost all LED lighting today will likely cause flicker when dimmed. And while that flicker may be annoying to some, to those with photophobia it could produce pain and the inability to lead a normal life.
Then there is the challenge of LED brightness. It doesn’t take a PhD in physics to realize that the brightness of an LED light source module is exceptionally high. Some of my work has involved the brightness of LED billboards, which are arrays of thousands of LED chips.
Their rapid change of intensity and color is exciting and eye catching – and epitomizes the physiological issues and environmental challenges of LED technology. I have measured outdoor LED signs at over 6000 nits (cd/m2)! And because most LEDs are phosphor coated blue diodes, there is a substantial amount of blue relative to the color temperature of the chip and its phosphor coating.
Mark Baker is the founder and president of the Soft Lights Foundation. It is an advocacy group “…. for the protection of people from the harms of visible light radiation emitted by light emitting diodes and for the protection of the natural night as a resource.” He founded the Soft Lights Foundation in 2021 as a registered 501(c)(3) non-profit in Oregon. The Foundation claims approximately 3,000 members via two Facebook Groups, Soft Lights Foundation and Ban Blinding LEDs
Why does Mark Baker maintain an on-going battle demanding greater regulation for LED lighting? According to Mark, “High luminance LED products were introduced into society without having been vetted for comfort, health, or safety. The many federal laws that exist to ensure protection of the public were skipped in the rush to convert to this new light source. Government officials have not understood that LED radiation has an entirely different set of physics characteristics compared to traditional light sources and that LEDs emit a directed energy light that can be exceedingly intense. Due to the combination of government officials ignoring existing laws and not understanding the physics of LED light sources, there are no regulations to protect the public from harm.”3
Like Ralph Nader and car safety, Mark knew something was amiss with LED lighting technology from the beginning. For a number of years he has been critical of LED flicker and has tried to raise concern. He started a web site, published articles, made phone calls, and finally raised sufficient concern and funding to sue the US government for not adequately addressing the spectral and flicker issues of LEDs.
After all, Haitz and other LED scientists were interested in the efficacy (lumens per watt) of white light, and they were far less interested in in how the LED sources would be powered (termed “driven”) or in related human considerations such as spectrum, glare, flicker and intensity. Not that they were bad scientists; they were in a race to significantly contribute to reduced energy consumption.
Most recently, Mark sued the US Food and Drug Administration for being “…the only federal agency that has the Congressional authority and mandate to regulate electromagnetic radiation from electronic products. Despite this mandate, the FDA has failed to publish performance standards for LED vehicle headlights, LED streetlights, LED light bulbs, LED flashing lights on emergency vehicles, LED lights on children’s shoes, and thousands of other products that use LEDs. The result of this failure is irreparable harm to millions of individuals and the environment.”4
On his website, he further claims that “…over 55,000 people have signed the petition to ban blinding LED headlights. LED streetlights have greatly increased light pollution and risk of disease such as macular degeneration of the eyes, cancer, diabetes, obesity, and mood disorders. LED flashing lights on emergency vehicles are increasing the risk of injury and death for first responders and the public. LED visible radiation is causing seizures, migraines, anxiety and numerous other adverse neurological reactions.”
His lawsuit aims to compel the FDA to comply with federal law and act to protect the public from the hazards of visible radiation emitted by light-emitting diode products.
No doubt, advancements in LED lighting have become a waterfall of lighting goodness, and like GM’s Corvair, the products’ faults are not obvious and may only affect some people. The fact that Pacific Northwest National Laboratories have identified impacts on human physiology by LEDs should be seen as legitimate recognition of Mark Baker’s concerns and should drive additional research and, ultimately, standards that limit brightness, flicker and other impacts, even if only affecting a percentage of the population. Like Ralph Nader, Mark has a point. ■
References
Britannica.com
https://my.clevelandclinic.org/health/symptoms/photophobia
https://www.softlights.org/the-failure-to-regulate-leds/
https://www.softlights.org/the-failure-to-regulate-leds/
