January 22, 2025
Renewed Debate: Streetlight Color and Health Implications
Lighting industry resistance, Dr. Motta's updated advice and the IES' strong response
Mario Motta, M.D., co-author of the American Medical Association's (AMA) pivotal 2016 report on the risks of streetlight color temperature, recently reignited discussions over blue-rich outdoor lighting during a recent appearance on the Restoring Darkness podcast. Dr. Motta recounted what he perceived as strong lighting industry opposition after the report was published, including “quite nasty” letters he claimed to have received from the Illuminating Engineering Society (IES) and allegations that commercial motives were driving resistance within the lighting industry.
This renewed focus comes as municipalities, departments of transportation and lighting professionals continue to wrestle with the implications of the AMA’s nine-year-old recommendation to adopt outdoor lighting with a correlated color temperature (CCT) of 3000K or lower to reduce health and environmental risks. In a notable update, Dr. Motta revealed that if the report were written today, he would advocate for even warmer lighting to better address melatonin suppression and its broader effects on public health.
Revisiting the 2016 AMA Report
The AMA’s 2016 report, titled "Human and Environmental Effects of Light Emitting Diode (LED) Community Lighting," highlighted the adverse effects of blue-rich lighting and recommended using streetlights with a correlated color temperature (CCT) of 3000K or lower. Co-authored by Dr. Motta, George Brainard, PhD, and Richard Stevens, PhD, the report emphasized blue light's ability to suppress melatonin, a hormone essential for regulating the sleep-wake cycle and supporting the immune system.
Melatonin suppression, as noted in the report, can disrupt circadian rhythms and weaken the body’s defenses against conditions such as cancer. The report also warned of potential environmental harms, including disruptions to ecosystems and wildlife.
Above: Excerpt from 2016 AMA report
In his recent podcast comments, Dr. Motta suggested that the AMA’s 2016 recommendation wasn’t strong enough: “If I were to rewrite the report today, I’d recommend 2700K or lower.” He emphasized the significance of the 479-nanometer wavelength, calling it “particularly problematic for melatonin suppression” due to its strong impact on the pineal gland. “We should figure out a way to eliminate the blue 479-nanometer wavelength from all street lights, and a lot of our problems will go away,” Dr. Motta stated.
Industry Pushback
Above: Dr. Mario Motta during a recent Restoring Darkness podccast
In 2016, the lighting industry’s response to the AMA report was swift and characterized by strong disagreement. Dr. Motta stated that much of the opposition he received was spearheaded by the IES, which issued demand letters to the AMA challenging the report’s findings and demanding retractions.
Dr. Motta revealed during the podcast that these letters, which he described as “quite nasty,” dismissed the expertise of the AMA’s medical contributors. According to Dr. Motta, the tone of these communications included assertions that he casually recapped as, “You're a bunch of doctors – you're not engineers. You don't know what you're talking about.”
In 2017, the IES formalized its opposition, issuing a statement that read in part: “The upper CCT limit of 3000K contained in AMA Policy H-135.927 lacks scientific foundation and does not assure the public of any certainty of health benefit or risk avoidance.” This statement exemplified the broader industry resistance to the AMA’s recommendations.
Balancing Commercial Interests and Health Interests
Dr. Motta criticized what he saw as commercialization driving industry pushback. He recounted how a major $1 billion project in Chicago became a battleground for the adoption of lower-CCT lighting. Initially, manufacturers and industry groups pushed for the use of 4000K and 5000K LEDs, products they had already heavily commercialized, prioritizing profits over emerging health concerns. Despite this pressure, Dr, Motta stated that the city ultimately rejected the higher-CCT options in favor of 3000K or lower lighting, aligning with recommendations to reduce blue-light exposure.
Dr. Motta emphasized the financial stakes tied to existing product designs and stockpiles of 4000K and 5000K fixtures as a driving force behind industry resistance to health-based lighting guidelines, illustrating how manufacturers prioritized business motives over adopting safer, lower CCT solutions.
The Alleged “180” by the IES
On the Restoring Darkness podcast, Dr. Motta described a shift in the IES’s stance on streetlight color temperatures, referring to documents published in 2022. He characterized a new IES stance as a “180,” aligning more closely with the AMA’s 2016 recommendations to limit blue-rich lighting — an assertion the IES disputes. More on that later.
In written comments shared with Inside Lighting in recent days, Dr. Motta clarified that while he believes the IES still supports the use of 4000K lighting in specific scenarios, such as intersections, their overall guidance has, in his view, moved strongly in the “right direction.” However, he acknowledged not owning a copy of the IES's latest publications and based his observations on information gathered from discussions with lighting engineers.
To examine this claim, we purchased and reviewed IES RP-8-22, Recommended Practice: Lighting Roadway and Parking Facilities, a cornerstone of the IES Lighting Library. While this document provides comprehensive guidance on roadway lighting, we couldn’t find explicit CCT recommendations among the 579 pages. It’s possible that Dr. Motta, or the lighting engineers he spoke with, were referring to another IES document within the Lighting Library.
IES’s Response to Dr. Motta’s Claims
Colleen Harper, Executive Director of the IES, denied Dr. Motta’s recent allegations, stating, “The statement that we revised our recommendations to align with the 2016 AMA report is ill-informed.” Harper, who has been leading the organization since 2022, emphasized the IES’s commitment to a balanced, research-driven approach.
Statement from the Illuminating Engineering Society:
The IES seeks to improve the lighted environment by bringing together those with lighting knowledge and by translating that knowledge into actions that benefit the public. The AMA report was responded to appropriately – both internally between the organizations and externally to the public – by an organization of our structure, goals, and composition. Anything else implied or reported is one person's perception of communication about an issue that took place almost a decade ago.
We have a professional staff, Board of Directors, and other respected advisors to address public statements and position statements when the need arises. A one-sided and narrow view on an incredibly important subject is not conducive to people being educated about IES, CCT, spectrum, etc. The statement that we revised our recommendations to align with the 2016 AMA report is ill-informed.
The IES is thorough, relies on our balanced perspective of members, and is communicative with other organizations when information is released that is detrimental to the public, premature, not in alignment with lighting research, and/or not derived from a balanced perspective. In addition to our detailed position statement on the AMA report, other organizations responded with similar concerns including the Lighting Research Center, NEMA, and the Department of Energy.
Harper emphasized other organizations joined the IES in opposing the AMA stance, including the Lighting Research Center, NEMA, and the U.S. Department of Energy. “A one-sided and narrow view on an incredibly important subject is not conducive to people being educated about IES, CCT, spectrum, etc.,” Harper added.
Department of Energy Pushback
The DOE addressed the concerns raised by the AMA’s 2016 guidance on street lighting and blue light exposure, noting that while well-meaning, the guidance overlooked several critical factors influencing individual exposure to short wavelengths.
According to the DOE, the issues attributed to LED lighting are not unique to LEDs and could apply equally to other light sources like incandescent, fluorescent, or metal halide at the same wavelength and intensity. The DOE emphasized the complexity of factors affecting potential health impacts, such as light intensity, exposure duration, timing within an individual’s circadian cycle, and overall health. Additionally, they highlighted the importance of considering modern societal behaviors, such as insufficient daylight exposure and pre-sleep activities like screen use, which may also contribute to circadian disruptions.
How Do We Resolve This?
The debate over streetlight color temperatures highlights the intersection of medical science, public health, and industry practices. While there seems to be consensus that blue light exposure suppresses melatonin production, the link to long-term health risks, such as cancer, remains inconclusive to some and requires further investigation.
A more nuanced discussion on blue light exposure can explore importance of duration and dosage. For instance, a 2022 study funded by the Department of Energy (DOE) found that at recommended roadway lighting levels, there was no significant suppression of salivary melatonin.
Addressing these issues demands transparent, evidence-based discussions that bring together scientists, policymakers, and industry leaders to prioritize public health without dismissing commercial realities. By fostering collaboration and a commitment to research, the lighting community can balance innovation with the well-being of the communities it serves.
Unless new scientific breakthroughs on this topic emerge, this debate seems poised to continue, dividing opinion between those who align with the AMA's recommendations and those who question the strength of the link to long-term health risks.
