Many products, including some that are indispensable to modern society, experience widespread adoption before consequential health and safety risks emerge. Sometimes these adverse effects are minimal, affect a small percentage of the population, or occur only in certain unlikely circumstances. The exposure to asbestos and lead concentrations in consumer paints, for example, can result in more dire consequences. In other cases, the perception of health and safety risks may not completely align with reality. Consider the attention that was paid to fears of a link between powerlines and cancer in the 1980s and ’90s. Courtesy of iStock.com/baona. The application of LEDs is already widespread, and use of the devices continues to expand. As such, it is important to recognize that these light sources present some health concerns to consumers. Much of the concern around LEDs pertains to brightness levels and the effect of high luminance on some individuals. While the lifetime, cost, brightness, and energy efficiency of these devices are well established, the risks are often overlooked, misunderstood, or left unaddressed. More than 13,000 incidents of pilot illuminations, or “laser strike” incidents, were reported last year. Although few pilots received retinal injuries from these events, the distraction factor during critical flight activities poses a major concern. Rather than the LED itself, however, it is the applications — and, most notably, a lack of application standards, guidelines, and awareness by designers — that pose the greatest risk. To be sure, LEDs are far from the only photonics technology area in which applications travel in a much faster lane than standards and regulations. Light response The focus on the harmful effects caused by LED illumination and strobing effects is largely derived from anecdotal discussions, although published reports raise the matter. In 2018, the European Commission published the Scientific Committee on Health, Environmental and Emerging Risks (SCHEER) report, Opinion on Potential risks to human health of Light Emitting Diodes. In its abstract, the report states that certain knowledge gaps exist in understanding potential risks to human health from LEDs. In terms of choosing sides, the report is by no means definitive in its assertion, but the report does identify a dilemma: the void that exists without bona fide conclusions that inform how a technology may affect those who are apt to use it. Another issue that pertains to the consumers who use LEDs involves the prevalence of LEDs. It ensures that pilots of nearly any vessel type as well as pedestrians and even those engaged in recreational activities will frequently encounter high-brightness sources during daily life. Yet, unlike the emergence of the laser, for which high-power capabilities were widely acknowledged from the start, LEDs began with low outputs and variations. Today, this hardly remains so. In fact, some modern deployments opt for LEDs specifically because of their extreme brightness capabilities. At Arnhem Terrace Tunnel in Derby, England, for example, authorities recently upgraded the legacy lighting system to high-brightness white light LEDs. The aim is to produce such a high level of illumination that people will opt to vacate the tunnel rather than use it for prolonged stays and/or recreational or illicit activity. There is no doubt that using readily available commercial technology is a boon for cost savings and maintenance. On the other hand, such an installation ought to give light source experts pause, especially amid the growing use of LEDs in automotive technology. A roadway with frequent automobile and, evidently, foot traffic is a challenging setting for an intentionally distracting bright light source. The distraction caused by LED headlights, and complaints about billboards and other LEDs on or above roadways, are already commonplace. Speaking of LEDs above roadways, airplane and helicopter pilots are also susceptible to LED light, as well as undesired light from other sources, such as laser pointers. More than 13,000 incidents of these so-called pilot illuminations, or “laser strike” incidents, were reported last year. Although few pilots received retinal injuries from these events, the distraction factor during critical flight activities poses a major concern. Exposure limits Though currently implemented beyond the scope of LEDs, exposure limits, as established by consensus standards and then regulations, play a critical role in safeguarding the public and the workers against a wide range of hazards. These limits exist for a range of chemical, physical, and energy measurables. Since these limits must be inclusive and consider adverse effects on physical as well as psychological well-being, there may be opportunities to consider “photo-psychological” exposure limits of incoherent artificial optical radiation. In applications that relate to transportation safety, high exposure levels can cause distractions, glare, flash blinding, and retinal damage. Each can lead to serious incidents in addition to extended negative health outcomes. In terms of standardization, it is important once again to separate concern about LEDs from LED-enabled applications. While there is a lamp standard, for example, it governs very few LED applications that pose serious risks to health and safety. At a time when LEDs have not yet plateaued in their capabilities and advantages — namely, cost effectiveness and illumination — it is important to remember that leaving technical applications unchecked, such as through an absence of standards and regulations, has frequently been shown to be a mistake. Designers and regulatory bodies must now consider appropriate limits. Further, they must extend their consideration beyond the traditional photochemical or photo- thermal effects and consider neurological manifestation, including migraines and seizures. Acknowledgments The author wishes to thank Mark Baker, Janine Manuel, and Randy Paura for their discussions and feedback on this topic.