by Julia Kampelman Stevenson
The District Department of Transportation (DDOT) is in the process of finalizing details of a years’ long effort to modernize more than 75,000 streetlights – a daunting task. The lights will all be converted to LED technology, the most energy efficient artificial light commercially available, having bulbs that last much longer and use less energy. This inherent energy efficiency will lead to greatly reduced operating costs and savings in energy use, diminishing our reliance on fossil-based carbon fuels.
While I wholeheartedly support this LED upgrade, I do have serious concerns, as artificial light has a profound impact on our environment in many significant ways.
LEDS and our health
Perhaps you’ve heard the distress of some neighbors in Chevy Chase DC, who, upon the installation of new LED alley lights, found night turned to day?
“We’ve had people complain because their children couldn’t sleep,” ANC 3/4G Commissioner Rebecca Maydak told WTOP. “…the adults can’t sleep… blackout shades don’t work because it comes around the shade.”
Lately, more attention is being paid to the negative health consequences of artificial light. Light is measured in a number of ways (lumens, watts, kelvin), but most of the worries regarding the ill effects of artificial outdoor street lighting are dramatically heightened as the measure of a light’s kelvins increases. Kelvin (k) is used to describe the color temperature of a light source.
When LED streetlights first appeared on the market they had color temperatures typically at 5000 k, but the excessive amount of strong white light they produced, with a cold harsh blue cast, was a significant deficiency. It is this bluer aspect of artificial lighting which is the more harmful.
According to the American Medical Association (AMA), blue-rich LED street lighting has been shown to be five times more disruptive to our sleep cycle than street lighting more yellowish in tone. Recent and sizable surveys have documented that exposure to cooler blue-rich white light at night disrupts the body’s circadian rhythm and interferes with melatonin production, ultimately making it harder for people to sleep and consequently impairing daytime functioning.
Additionally, the AMA has concluded that blue-rich lights have far more glare than the warmer lights and are more hazardous to drivers and pedestrians, as they diminish our ability to discriminate contrasts. Furthermore, there is a growing body of medical evidence that implicates higher kelvins with increased risks for retinal damage, diabetes, cancer, cardiovascular disease and obesity.
The Chevy Chase alley in the example above has 4000 k lights. The streetlights illuminating Connecticut Avenue at Park Van Ness Apartments (4455 Connecticut) are a whopping 4500 k.
There have been considerable advancements in LED technology, and LEDs are now available with much lower kelvins, producing a much softer hue with amber overtones, but with roughly the same energy efficiency as those with higher kelvin ratings. Notably, these new LEDs, with their lower k option, give us the opportunity to select lights which don’t radiate anywhere near as much potentially harmful blue light.
A report the AMA released in 2016 specifically recommends that outdoor lighting installations use LEDs no higher than 3000 k.
“It is advisable that bulbs be selected that operate at the lower end of the light spectrum, lower kelvins, producing a warmer, more yellowish-white, avoiding the cool blue light that approximates bright sunshine that higher kelvin degrees give out.”
LEDs and nature
There is yet more reason to be worried about the quantity and quality of artificial light that spills out into the night. The International Dark-Sky Association (IDA) is one of the leading organizations fighting light pollution. It also recommends using LED lighting that has a color temperature of no more than 3000 k, with the prognosis that quite soon, the “new normal” will be lower.
Blue light brightens the night sky more than any other color of light. Exposure to blue light at night has not only been proven to harm human health but it also endangers wildlife; other species are just as vulnerable as humans to disruption of their circadian rhythms.
The AMA addresses this concern as well: “Excessive outdoor lighting disrupts many species that need a dark environment. For instance, poorly designed LED lighting disorients some bird, insect, turtle and fish species…”
All animal and plant species depend on the cues and triggers that they receive from both seasonal and circadian prompts. Artificial light can cause these species to respond to stimuli that is mistimed. Behaviors such as migration can be prompted too early or too late, so missing ideal climate conditions for any given species’ nesting and foraging needs. And the synergistic interplay between species can be disrupted, whether actions primarily integral to survival – such as reproductive or predator/prey interactions – or those actions having secondary consequences, as between plant crops and pollinators.
“When we add light to the environment, that has the potential to disrupt habitat, just like running a bulldozer over the landscape can,” said Chad Moore, formerly of the National Park Service (NPS) and a founder of the NPS Night Sky Team.
What about safety?
Outdoor lighting is an effective tool in enhancing safety and security at night. The trick is to direct the appropriate amount of light where it is needed – to strategically target an area – in order to both promote safety and support a desirable balance between safety and starlight.
Both the AMA and IDA note that properly housing the bulbs will simultaneously boost light’s efficacy and further reduce light pollution. They specify that to reinforce these objectives, “full-cutoff” fixtures should be used that are downward-pointing – so as to minimize glare, light spillover (or “trespass”) and skyglow, which is a brightening of the night sky (from both natural and human-made factors). As the IDA points out, a dark sky does not necessarily mean a dark ground.
Lighting the way forward
Across the country, municipalities are making this transition to LEDs. Many did so rather quickly after the technology became available, and at that point the choices were limited. As the technology has advanced and more choices have become available, and more research has ensued, cities have become more discerning. Just as there is now an understanding that it is ill-advised to venture over 3000 k LEDs, there is also a growing awareness that we can reach for better.
In that Chevy Chase alley, DDOT has committed to replacing the 4000 k bulbs with lower-intensity 2700 k LEDs. It’s unclear what the Park Van Ness lights will be dialed down to, but DDOT has said its new standard for city lights places 3000 k as the upper limit.
But what of the city in general? DDoT is considering a combination of 3000 k and 2700 k LEDs in DC’s overall lighting plan.
We can do even better. I would like to see DC adopt a lighting plan throughout its jurisdiction that simply specifies 2700 k LEDs.
Remember, the AMA called for “the lowest emission of blue light possible…”
If 3000 k bulbs remain in DDOT’s plan, the proposal as such would install 2700 k bulbs on local residential streets and 3000 k bulbs would be reserved for arterial streets such as Connecticut, Wisconsin and Nebraska Avenues, as well as DC’s Business Improvement Districts (BIDs). This may seem neatly figured but it’s important to remember that such demarcations aren’t so cleanly laid out. Some of the arterial streets run through neighborhoods or are themselves streets that people live on, while there is ample overlap of BIDs with residential areas.
Other cities, differing in size and character, have committed to installing 2700 k LEDs.
In terms of population, Phoenix, Arizona is the sixth largest city in the U.S. Originally, its city council had a plan to install 4000 k LEDs, but it was withdrawn after wide-ranging community input gave voice to ardent feelings heedful of environmental concerns. Newly specifying 2700 k LEDs throughout the city, Phoenix began its conversion work in the fall of 2017.
At this moment in DC, we have a remarkable opportunity to advantageously affect profound and conscientious change on the environment in which we all live. We can be aspirational in our pursuit of smart lighting for our city.
The District is collecting comments on the streetlight modernization plan. You can submit them by email to: firstname.lastname@example.org.
City Wildlife, a wildlife rescue and rehabilitation center in DC. Its “Lights Out DC” program is an effort “to convince building owners and managers to adopt light abatement procedures for the sake of migrating birds.”
FLAP Canada, the Fatal Light Awareness Program, originally focused on the effects of nighttime lights on migrating birds.