Light Pollution Clouds the Night Sky
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Credit: Photograph by Brad Goldpaint

Our indiscriminate overuse of outdoor lighting is the main cause of light pollution. We light our driveways, our porches, our parking lots, our billboards and storefronts, our streets and highways, our parks and public spaces – at times for the purpose of commerce, but often because, on a gut level, it just feels safer to have bright lights around at night. But much of our outdoor lighting is poorly designed, blasting light into the sky rather than onto the sidewalk or city street we're actually meaning to illuminate. Outsize spotlights used for architectural lighting – say, to highlight a flagpole or church steeple – could be replaced with seven-watt LED spots that would work just fine. Likewise, many safety concerns could be addressed with better targeted, lower-wattage lighting, in some cases activated solely by motion detectors; improperly aimed floodlights, perversely, wind up creating blinding glares that can make it easier for would-be criminals to lurk in the shadows.

In certain obvious, unfortunate ways, light pollution has simply evolved alongside our lighting technology. As Paul Bogard points out in the new book 'The End of Night,' a single 75-watt incandescent bulb burns 100 times brighter than a candle. Satellite images of North America at night, with various intensities of light represented by glowing yellows and oranges, are startling, with just about everything east of the Mississippi looking like a graphic representation of a toxic spill. Sky glow has transformed the color of night, for many of us, into perpetually dizzying gradations of pink and blue. A 2001 study co-authored by scientists from Italy and the U.S. found that for 80 percent of the U.S. population and two-thirds of the European Union population, night-sky brightness equaled full-moon conditions all month long. "They therefore effectively live in perennial moonlight," the study concluded. "Night never really comes for them." (The authors also took note of the unusual amount of night visibility in Venice, the only Italian city with a population greater than 250,000 in which residents can typically see the Milky Way from the city center; they attributed this fact "mainly to the unique low-intensity romantic lighting of this city, which deserves to be preserved.")

Meanwhile, Richard Stevens, an epidemiologist at the University of Connecticut, has conducted research suggesting that lengthy exposure to bright, artificial lights at night (computer screen, television, streetlamps) causes circadian disruption in humans, resulting in the body producing lower amounts of melatonin, a hormone that fights cancer and suppresses tumor growth. Night-shift workers, according to Stevens' study, are nearly twice as likely to develop breast cancer as day-shift workers. A 2012 report by the American Medical Association noted, "Biological adaptation to the sun has evolved over billions of years. The power to artificially override the natural cycle of light and dark is a recent event and represents a man-made self-experiment," adding that "even low-intensity nighttime light has the capability of suppressing melatonin release." Aside from "potential carcinogenic effects," the AMA report states that circadian disruption could also exacerbate other health problems, including obesity, diabetes, mood disorders, depression, and reproductive issues, and calls for minimizing light pollution and further study of its potential effects.

University of Southern California professor Travis Longcore has written about the effects of light pollution on animals. Migrating birds become disoriented by lights and crash into tall, lighted buildings and broadcasting towers; newly hatched sea turtles crawl toward artificial lights (rather than the moonlight over the sea) and wind up crushed by cars or eaten by predators; nocturnal insects flock around city lights, dying in large numbers and disrupting the feeding of bats and other animals higher on the food chain (a study in Germany found that approximately 150 insects are killed by each German streetlight every night). "A pollutant is only a pollutant because we call it such," Longcore told 'Cabinet' magazine. "Carbon dioxide, of course, has been produced on Earth for billions of years, but we now consider it a pollutant because it's more abundant than it would be naturally. In the same way, we can think of light as polluting when it's more prevalent than it would be naturally."

One of Parks' first light-pollution campaigns, to help a local county adopt a strict lighting ordinance, became a teachable moment for him after one of the board members showed up at a public meeting dressed as Santa Claus, claiming the new laws would ban Christmas lights. "He was just a buffoon, playing on everybody's fears," Parks recalls. "He didn't care about the lights. He was just against regulation. He was a Tea Party guy before there was a Tea Party." The ordinance was never enacted, and Parks learned a crucial lesson about the importance of education: Bad lighting is something the average citizen rarely notices unless it's pointed out. "That's the number one problem," Parks says, sighing. "You never miss what you don't know is there. I'd say 90 percent of the population now doesn't miss dark skies. They've never seen them! And that's really, really sad."

Outside the restaurant's plate-glass window, dusk has fallen, and the headlights of the cars gliding along K Street have turned themselves on. Stepping onto the sidewalk, Parks immediately scowls up at an ornamental streetlamp. "This city has probably the worst lighting in the country, and this is the worst streetlight ever invented," he says. I have to admit (though I don't, not aloud and in Parks' presence), I rather like the design of the light: a slightly filigreed metal post rising up to an old-fashioned, mostly exposed acorn-shaped bulb known as a Washington globe. Unfortunately, because of the utter lack of shielding, more than 50 percent of the light shines up into the sky, serving no useful purpose, and about 20 percent radiates directly at eye level, creating glare. "You're working against visibility by using a light like this one," Parks says. "But people love the way they look during the day. I'd have no problem if they didn't turn them on at night. Or if they just put candles in them, the way they were designed."

Parks turns onto 16th Street, wandering in the direction of the Capitol Hilton. A series of small lights buried in the center of some shrubbery, designed to light up the landscaping from within, stops him in his tracks. "People like lights in bushes," he notes disapprovingly, adding, "Unshielded, but they're hidden, so that's OK." The exterior of the hotel is highlighted by lights coming out of unshielded wall packs, but Parks says the pale paint job of the walls and the brightness of the surrounding streetlamps makes this choice unobjectionable.

At the sight of a restaurant's brightly backlit sign, Parks pulls out his smartphone and opens a folder of apps labeled "Lighting Tools." Photographing the sign, he uses one of the apps to map the amount of light being generated. The photo turns different neon colors, mostly green and yellow, with a tap of his finger displaying the number of lumens that section of the light source is emitting. "Fifty-five," Parks says. "Though in reality, it's probably 100. And it's white light, which is the worst."

Parks' mood seems to be darkening with the night sky – which is not all that dark, Parks would surely point out – but still, the growing dimness allows the sheer amount of horrible lighting surrounding us to assume a much sharper focus. "That is just hellishly bright," he says as we come across another Washington globe.

At the same time, Parks is not unsympathetic to the hardwired human yearning to vanquish the night. "We light because we are innately afraid of the dark," he says. "Psychology ends up driving public policy: No politician will ever get fired for putting up outdoor lighting. The public feels safe during the day, and there's a feeling that ultimately, the best thing would be for night to be like day."

After Parks and I part ways, I head toward the National Mall. Others had warned me that once you start hanging around with light-pollution people, it's impossible to unsee the matrix – in this case, an inescapable grid of harsh and aesthetically offensive lighting. And it's true! A garish LED sign outside a bank, informing customers they can "Deposit in a Flash" with their smartphones, bathes a long stretch of sidewalk in a sickly irradiated glow. Staring into a park lit entirely by Washington globes actually makes my eyes hurt. It's much darker on the Mall, where lighting is minimal along the major paths and nonexistent by the Reflecting Pool. Still, I can see only about a dozen stars, thanks to the sky glow from the rest of the city.

The Lincoln Memorial looks beautiful in the distance, spotlighted in a way that seems to give the whiteness of the marble a living pulse, and with such a high-definition gleam on Abe himself, he could pass for a hologram. The flashes of dozens of tourist cameras sparkle like lightning bugs. A guy rides past on a bike with a kaleidoscopic array of glow sticks weaved into his spokes. I start back in the direction of my hotel and suddenly my newly light-sensitive eyes become slits: Near the Washington Monument, some kind of giant globe light has doused a cluster of trees and the surrounding sky.

I'm about to snap a photograph and fire off an angry email to Parks when I realize it's the full moon.

On the plus side, light pollution is fundamentally a much simpler problem to tackle than most other kinds of pollution. It doesn't require the sort of life-pattern-altering tectonic shifts necessary for, say, weaning ourselves from oil or coal or factory-farmed meat. Our relationship to outdoor illumination remains a fairly passive one. If our towns decided to change the streetlamps, few of us, with the exception of the Santa-suit guy, would care, or even notice, until the night sky made its dramatic reappearance.

And as Bob Parks points out, solid-state LED lighting is coming online that could radically change the way we light cities. "You get this opportunity only about once a century," Parks says. "We're moving from a very mechanical way of lighting things – putting glowing elements inside glass, which is technology that was around a hundred years ago – to the sort of technology we've used to build computers. And we'll see that same rapid curve we got with computers, where efficiency will go up and up and up and at the exact same time cost will go down."

Jeffrey Cassis, the CEO of Philips' Color Kinetics division, who has spent years working on LED development, agrees: "The technology is there – now we're trying to get the cost down. And it's moving down very rapidly. Probably less than 1 percent of lighting in cities is now smart LED lighting. Think about how much of how we light our cities is being left to humans deciding to turn things on and off!" The alternative, Cassis and other experts say, will be smart grids allowing for automatic dimming of lights, either pegged to time of day – a particular neighborhood could, say, decide its streetlamps should be lowered significantly after midnight – or even more specific triggers. In San Jose, California, the comprehensive LED retrofit being installed will let streetlights become brighter when sporting events or concerts let out or when bars close. Nancy Clanton, an architectural engineer based in Boulder, Colorado, who has become one of the premier dark-sky lighting designers in the country, predicts future streetlights will have the ability to detect approaching cars (or pedestrians carrying mobile phones) and brighten automatically. "Unfortunately, everyone knows where we are at all times with GPS, so we might as well put it to good use," she notes cheerily.

Clanton has upgraded municipal lighting systems across the country, and says she initially approached the issue as a design challenge. She points out that streetlamps, for example, are typically set upon 30- or 40-foot poles – but what if a second, much lower tier of luminaires were built into the poles to light the sidewalks? Or how about curb-level lighting that would blast lights into crosswalks, so anyone in the street could be immediately seen by cars? "Now," Clanton says, "we can light the curbs themselves, or the stripes of crosswalks, or vertical strips on Jersey barriers" – the low concrete walls on the sides of highways – "all of which is much more important than shining light down on everything. Do you ski? Go skiing one day when the light is flat. You can't see bumps! That's why we need layering in our lighting – which, by the way, we've been doing in interiors for years."

Seattle has been using federal stimulus money to retrofit all 40,000 of its residential streetlights. Clanton points to a study conducted in that city in which nearly 450 participants responded to different outdoor lighting in various weather conditions. Stunningly, even when lighting was reduced to a mere 25 percent of its normal level, respondents continued to feel safe and secure – as long as the fixtures were targeted white lights with low glare. "Lighting level made no difference to people," Clanton says. "In fact, they didn't even know it was lower lighting!"

Research conducted by Virginia Tech's Transportation Institute had passengers ride in vehicles on a mile and a half of test roadways. The vehicles traveled at 35 miles per hour, and passengers were instructed to press a button whenever they spotted an object in the road. Again, the tests took place in all sorts of conditions – wet, dry, various lighting levels – and the researchers found that lighting level made no difference on task detection if lights were properly designed. "So now we have both objective and subjective data," Clanton says. All the data points to the fact that we've been designing lighting all wrong for years. "They were designing for one parameter: lighting level," says Clanton. "Which we've found out is the worst predictor for visibility. What's much more important is glare and contrast. It's the quality of light – having really good optical design. And now with computers we can model everything, including contrast. Our tools are completely different. Back then, they could not analyze glare."

Of course, had those same citizens been subjects of a telephone poll, many would have voted for more lighting, which intuitively feels safer, so education remains a key component of any future political fights. Clanton says she likes to ask people if they've ever taken a moonlit walk. "They'll typically say, 'Oh, yeah; it's so great.' And I'll tell them, 'You know, you can read 12-point print under full moonlight!'" Foot candles are units used to measure light intensity. A typical streetlamp, Clanton says, is one foot candle. The brightness of a full moon is one-100th of a foot candle.

At the same time, groups like the IDA have been pushing municipalities to adopt stricter lighting ordinances. Plymouth, Minnesota, a suburb of Minneapolis with a population of 70,000, became the first city in the U.S. to adopt the IDA's comprehensive model lighting ordinance, which mandates specific amounts of shielding and caps brightness. The city council of Malibu, California, voted unanimously to adopt its own version of the ordinance in April as a direct response to the wild overlighting of a shopping center and football field. Arizona cities like Flagstaff and Tucson have long had strict lighting laws on the books that ban, for instance, searchlights and unshielded parking-lot lights. Both cities are surrounded by observatories, and some believe Flagstaff, a dry, high-elevation locale that has attracted stargazers since the 1890s, when it earned the nickname Skylight City, passed the first lighting restrictions in the country in 1958 in order to protect its skies.