Responsible outdoor lighting Getting a handle on light pollution

Responsible outdoor lighting

Getting a handle on light pollution

provided by International Dark-Sky Association

Too often, outdoor electric lighting installations at night are over lit, left on when not needed,

and are harmful to the environment. As a result, light pollution is a growing global issue that can negatively affect our environment and impact our quality of life. The International Dark-Sky Association (IDA) and the Illuminating Engineering Society have published the joint Five Principles for Responsible Outdoor Lighting. By joining forces, our shared goal is to prevent and reduce light pollution through the proper application of quality outdoor electric lighting. By applying these principles, properly designed electric lighting at night can be beautiful, healthy, and functional. Projects that incorporate these principles will save energy and money, reduce light pollution, and minimize wildlife disruption.

Outdoor lighting basics

Types of light Most people are familiar with incandescent or compact 4 fluorescent bulbs for indoor lighting, but outdoor lighting usually makes use of different, more industrial sources of light. Common light sources include low-pressure sodium (“LPS”), high-pressure sodium (“HPS”), metal halide, and, most recently, light emitting diodes (“LEDs”). > LPS is an old technology that is no longer being manufactured. It was favored for use around observatories and some environmentally sensitive areas. Narrow-band amber LEDs emulate the color. > HPS is commonly used for street lighting in many cities. Although it still emits an orange-colored light, its coloring is more “true to life” than that of LPS. > In areas where it’s necessary to use white light, two common choices are metal halide and LEDs. One of the advantages of LED lighting is that it can be dimmed. Thus, instead of always lighting an empty street or parking lot at full brightness, LEDs can be turned down or off when they aren’t needed and then brought back to full brightness as necessary. This feature both saves on energy and reduces light pollution during the night. Because of their reported long life and energy efficiency, LEDs are rapidly coming into widespread use, replacing the existing lighting in many cities. Photo by Greg Jeanneau on Unsplash However, there are important issues to consider when making such a conversion. See our LED Practical Guide for more information:

darksky.org/our-work/lighting/lighting-forcitizens/led-guide

Color matters It is crucial to control upward-directed light, but we now 4 know that the color of light is also very important. Both LED, and metal halide fixtures contain large amounts of blue light in their spectrum. Because blue light brightens the night sky more than any other color of light, it’s important to minimize the amount emitted. Exposure to blue light at night has also been shown to harm human health and endanger wildlife. IDA recommends using lighting that has a color temperature of no more than 3000 Kelvins.

Lighting with lower color temperatures has less blue in its spectrum and is referred to as being “warm.” Higher color temperature sources of light are rich in blue light. IDA recommends that only warm light sources be used for outdoor lighting. This includes HPS and low-colortemperature LEDs. In some areas, the white light of even a low-color-temperature LED can be a threat to the local nighttime environment. In those cases, narrow-spectrum amber LEDs are the preferred choice.

Finding what you need

IDA doesn’t sell dark sky-friendly lighting, but our Fixture Seal of Approval (FSA) program makes it easy for you to find the right products. The FSA program certifies dark sky-friendly outdoor lighting – these are fixtures that restrict upward-directed light and have low color temperature, meaning that they minimize glare while reducing light trespass and skyglow. Learn more:

darksky.org/our-work/lighting/lighting-for-industry/ fsa/fsa-products/

The effects of light pollution

Wildlife and ecosystems For billions of years, all life has relied on Earth’s 4 predictable rhythm of day and night. It’s encoded in the DNA of all plants and animals. Humans have radically disrupted this cycle by lighting up the night. Plants and animals depend on Earth’s daily cycle of light and dark rhythm to govern life-sustaining behaviors such as reproduction, nourishment, sleep and protection from 4 predators. Scientific evidence suggests that artificial light at night has negative and deadly effects on many creatures including amphibians, birds, mammals, insects and plants.

Artificial lights disrupt the world’s ecosystems.

Nocturnal animals sleep during the day and are active at night. Light pollution radically alters their nighttime environment by turning night into day. According to research scientist Christopher Kyba, for nocturnal animals, “the introduction of artificial light

probably represents the most drastic change human beings have made to their environment.” “Predators use light to hunt, and prey species use darkness as cover,” Kyba explains “Near cities, cloudy skies are now hundreds, or even thousands of times brighter than they were 200 years ago. We are only beginning to learn what a drastic effect this has had on nocturnal ecology.” Glare from artificial lights can also impact wetland habitats that are home to amphibians such as frogs and toads, whose nighttime croaking is part of the breeding ritual. Artificial lights disrupt this nocturnal activity, interfering with reproduction and reducing populations.

New lighting technologies can help conserve energy.

Artificial lights have devastating effects on many bird

species. Birds that migrate or hunt at night navigate by moonlight and starlight. Artificial light can cause them to wander off course and toward the dangerous nighttime landscapes of cities. Every year millions of birds die colliding with needlessly illuminated buildings and towers. Migratory birds depend on cues from properly timed seasonal schedules. Artificial lights can cause them to migrate too early or too late and miss ideal climate conditions for nesting, foraging and other behaviors. Many insects are drawn to light, but artificial lights can create a fatal attraction. Declining insect populations negatively impact all species that rely on insects for food or pollination. Some predators exploit this attraction to their advantage, affecting food webs in unanticipated ways.

Energy and money

Lighting that emits too much light or shines when and where it’s not needed is wasteful. Wasting energy has huge economic and environmental consequences. In an average year in the U.S. alone, outdoor lighting uses about 120 terawatt-hours of energy, mostly to illuminate streets and parking lots. That’s enough energy to meet New York City’s total electricity needs for two years! IDA estimates that least 30 percent of all outdoor lighting in the U.S. alone is wasted, mostly by lights that aren’t shielded. That adds up to $3.3 billion and the release of 21 million tons of carbon dioxide per year! To offset all that carbon dioxide, we’d have to plant 875 million trees annually. Environmental responsibility requires energy efficiency and conservation. > Installing quality outdoor lighting could cut energy use by 60–70 percent, save billions of dollars and cut carbon emissions.

> Outdoor lighting should be fully shielded and direct light down where it is needed, not into the sky. > Fully shielded fixtures can provide the same level of illumination on the ground as unshielded ones, but with less energy and cost. > Unnecessary indoor lighting – particularly in empty office buildings at night – should be turned off. > LEDs and compact fluorescents (CFLs) can help reduce energy use and protect the environment, but only warm-white bulbs should be used. Learn more about LEDs and color temperature from our LED Practical Guide (see link earlier in this article). > Dimmers, motion sensors and timers can help to reduce average illumination levels and save even more energy. Quality lighting design reduces energy use and therefore energy dependence. It also reduces carbon emissions, saves money and allows us to enjoy the night sky.

Lighting, crime and safety

There is no clear scientific evidence that increased outdoor lighting deters crimes. It may make us feel safer, but has not been shown to make us safer. A 2015 study published in the Journal of Epidemiology and Community Health found that streetlights don’t prevent accidents or crime, but do cost a lot of money. The researchers looked at data on road traffic collisions 4 and crime in 62 local authorities in England and Wales and found that lighting had no effect, whether authorities had turned them off completely, dimmed them, turned them off at certain hours, or substituted low-power LED lamps. According to the study, “[W]hen risks are carefully considered, local authorities can safely reduce street lighting saving both costs and energy … without necessarily impacting negatively upon road traffic collisions and crime.” According to a 2011 study of London street lighting and crime, there is no good evidence that increased lighting reduces total crime.” A 1997 National Institute of Justice study concluded, “We can have very little confidence that improved lighting prevents crime.” The truth is bad outdoor lighting can decrease safety by making victims and property easier to see. A Chicago Alley Lighting Project showed a correlation between brightly lit alleyways and increased crime.

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In fact, most property crime occurs in the light of the day. And some crimes like vandalism and graffiti actually thrive on night lighting. A dark sky does not necessarily mean a dark ground. Smart lighting that directs light where it is needed creates a balance between safety and starlight.

Brighter does not mean safer. According to a 2012 report of the American Medical Association, “Glare from nighttime lighting can create hazards ranging from discomfort to frank visual disability.” Outdoor lighting is intended to enhance safety and security at night, but too much lighting can actually have the opposite effect. Visibility should always be the goal. Glare from bright, unshielded lights actually decreases safety because it shines into our eyes and constricts our pupils. This can not only be blinding, it also makes it more difficult for our eyes to adjust to low-light conditions.

Human health

Humans evolved to the rhythms of the natural light-dark cycle of day and night. The spread of artificial lighting means most of us no longer experience truly dark nights. Research suggests that artificial light at night can negatively affect human health, increasing risks for obesity, depression, sleep disorders, diabetes, breast cancer and more.

Circadian rhythm and melatonin. Like most life on Earth, humans adhere to a circadian rhythm — our biological clock — a sleep-wake pattern governed by the day-night cycle. Artificial light at night can disrupt that cycle. Our bodies produce the hormone melatonin in response to circadian rhythm. Melatonin helps keep us healthy. It has antioxidant properties, induces sleep, boosts the immune system, lowers cholesterol, and helps the functioning of the thyroid, pancreas, ovaries, testes and adrenal glands. Nighttime exposure to artificial light suppresses melatonin production. Not all artificial light Is created equally. Exposure to blue light at night is particularly harmful. Unfortunately,most LEDs used for outdoor lighting — as well as computer screens, TVs, and other electronic displays — create abundant blue light. According to experts at Harvard Medical School, “If blue light does have adverse health effects, then environmental concerns, and the quest for energy-efficient lighting, could be at odds with personal health. Those curlicue compact fluorescent lightbulbs and LED lights are much more energy-efficient than the old-fashioned incandescent lightbulbs we grew up with. But they also tend to produce more blue light.” A 2016 American Medical Association report expressed concern about exposure to blue light from outdoor lighting and recommends shielding all light fixtures and only using lighting with 3000K color temp and below. To minimize harm from blue light in your home, choose the right light bulb and download a color temperature app that adapts your electronic screen to the time of day – cool light during the day and warm light at night: > F.lux is available for Mac OS/X, Windows, Linx and (jailbroken) iPhones and iPads. > For those with Apple devices using the iOS 9.3 operating system and above, the Night Shift app is pre-installed. > Lux is available for Android devices free or for pay. > Twilight is available for smartphones or tablets.

Choosing the right bulb. Be sure to look at the packaging. All packaging for new CFL and LED light bulbs provide color temperature information. Use low color temperature light sources for interior and exterior light. Their light is less harsh and less harmful to human health and the environment. Look for warm white sources with a color temperature of 3000K or lower. The Kelvin temperature chart below shows you what the numbers mean.

Kelvin Temperature Scale.Higher color temperatures mean bluer light, the kind that should be avoided after dusk.

Glare from bad lighting is a safety hazard. Glare from poorly shielded outdoor lighting is also harmful to your health, because it decreases vision by reducing contrast. This limits our ability to see potential dangers at night. Aging eyes are especially affected. “Glare from nighttime lighting can create hazards ranging from discomfort to frank disability.” — American Medical Association Council on Science and Public Health (2012)

Content and graphics courtesy of the International Dark Sky Association. Learn more at darksky.org.