There was a time when street lighting means someone had to go light the lamps. Electricity changed that, but street and outdoor lighting has been quietly going through a new revolution: LEDs. The problem, though, is that LEDs provide what scientists call “broad white” light and there are concerns about the impact the unnatural lighting will have on ecosystems, including people and animals.

The data shows that LED adoption is happening at different rates in different countries and the paper discusses the potential biological impacts ranging from melatonin production to impacting the lives of insects and bats. Besides that, the sensors used to measure the intensity of artificial life from space now respond to the wrong wavelengths, and are thought to underreport readings as more and more LED lighting appears. The real gem, though, is the Materials and Methods section discussing how they processed and calibrated the data.

Environmental risks from artificial nighttime lighting widespread and increasing across Europe
https://www.science.org/doi/10.1126/sciadv.abl6891

The nighttime environment of much of Earth is being changed rapidly by the introduction of artificial lighting. While data on spatial and temporal variation in the intensity of artificial lighting have been available at a regional and global scale, data on variation in its spectral composition have only been collected for a few locations, preventing variation in associated environmental and human health risks from being mapped. Here, we use imagery obtained using digital cameras by astronauts on the International Space Station to map variation in the spectral composition of lighting across Europe for 2012–2013 and 2014–2020. These show a regionally widespread spectral shift, from that associated principally with high-pressure sodium lighting to that associated with broad white light-emitting diodes and with greater blue emissions. Reexpressing the color maps in terms of spectral indicators of environmental pressures, we find that this trend is widely increasing the risk of harmful effects to ecosystems.

COVID-19 has forced humans to stay indoors these past few months, which has been beneficial for the air, water, and wildlife.

One thing that hasn’t changed despite our absence is the outdoor lighting installed to facilitate human activities at night

The inherent differences between the human visual response and the behavioral response and visual sensitivity of animals opens the door to the identification of spectra for outdoor lighting that minimizes detrimental impacts to wildlife while still providing adequate illumination for humans. A research article entitled “Rapid assessment of lamp spectrum to quantify ecological effects of light at night” provides some insight into the implications of the widespread adoption of LED lighting in terms of predicting the effects of the spectral power densities (SPDs) of various lighting products on wildlife.

The study looked at the impact of 24 artificial light sources (of various lighting technologies, including LED), on the behavior, visual sensitivity, and physiological response of insects, sea turtles, the Newell’s shearwater bird, and juvenile salmon against four parameters: correlated color temperature (CCT), color rendering index (CRI), sky glow, and melatonin suppression (blue light content). Of these parameters, CCT appeared to have the strongest correlation to wildlife impacts, with warmer CCTs, in general, resulting in fewer adverse effects to the studied species. This conclusion has significant implications for LED lighting installations because, unlike legacy lighting technology (e.g., low-pressure sodium), the SPD of an LED product can be custom-tailored to a particular application.

There is a shortcoming to the use of CCT as the lone metric for evaluation of potential impacts in that light sources with significantly-different SPDs can still have the same CCT.

While research into the impacts of artificial lighting on specific species is ongoing, the bottom line for minimizing harm cannot be disputed: low CCT lighting, although straight-forward and simple, is not a one-size-fits-all solution. In addition to an appropriate CCT, projects must emphasize timing, intensity, and distribution, that is, provide light only when needed, at only the needed intensity, and directed only where needed.

A number of LED-based outdoor lighting projects designed with these principles in mind have been implemented recently. One the most publicized adverse wildlife impacts involves sea turtle hatchlings. Upon emerging from their nests in the sand, they are drawn to the sea by the light of the moon shining upon it, but artificial lights easily disorient the hatchlings, often leading to their deaths.

Pole lighting along the shoreline features a circular shield at the top (for dark sky considerations) and an additional half-shield that directs the light away from the sea. Further, the LED lighting is a low CCT amber to differentiate it from the cool-white of the moon. Other installations have focused on the well-being of birds, bats, and even polar bears, each using LED products with output spectra selected specifically to minimize harmful effects.

small pilot study that suggests a few minutes of looking into a deep red light could have a dramatic effect on preventing eyesight decline as we age. CNN reports:
Researchers recruited 12 men and 12 women, whose ages ranged from 28 to 72. Each participant was given a small handheld flashlight that emitted a red light with a wavelength of 670 nanometers. That wavelength is toward the long end of the visible spectrum, and just short of an infrared wavelength, which tends to be invisible to the human eye. They spent three minutes each day looking into the light over a period of two weeks. The lights work on both cones and rods in the eye. Cones are photo receptor cells that detect color and work best in well-lit situations. Rods, which are much more plentiful, are retina cells that specialize in helping us see in dim light, according to the American Academy of Ophthalmology.

https://edition.cnn.com/2020/06/30/health/declining-eyesight-red-light-scn-wellness/index.html

Does blue light from your phone or computer negatively affect your ability to sleep?

The European Union Scientific Committee on Health, Environment and Emerging Risks published research stating that there is no health risk for healthy humans to be exposed to LEDs in the normal use of lighting and display products.

The European Union (EU) Scientific Committee on Health, Environment and Emerging Risks (SCHEER) has published a lengthy draft report entitled “Potential risks to human health of LEDs.” The overall conclusion in the report states. “The Committee concludes that there is no evidence of direct adverse health effects from LEDs in normal use (lighting and displays) by the general healthy population.”

Of course, there has been a long debate in the lighting sector as to whether the short-wavelength blue energy peak associated with most phosphor-converted white LEDs can pose a risk to the human eye as solid-state lighting (SSL) usurps the lighting market. The US Department of Energy (DOE) has addressed the issue several times.

The EU had tasked SCHEER with studying the issue exhaustively with the specific direction to evaluate the impact of blue energy on human eyes and skin. The committee determined that typical human exposure to such blue energy from lighting and displays is far lower than exposure safety limits that have been previously established. And the report said the lack of ultraviolet (UV) light in LED sources may reduce the risk humans face from UV in other light sources including the Sun.

The report does warn of potential issues with LEDs including discomfort and disability glare associated with SSL implementations in auto headlamps and other applications. Those issues are solely present in LEDs. The report also mentions glare related to street lighting but points out that glare has been a problem primarily where lighting design and luminaire selection has favored energy efficiency over quality. In any case, the glare issue is said to have a temporary and not permanent impact on healthy humans.

The report further concludes that some LED products can have a greater impact on circadian rhythm relative to legacy sources, yet it goes on to say that there is no current evidence that circadian disturbance leads to adverse health effects.