Light pollution affects far more than our ability to see the Big Dipper and its glimmering companions, and while it’s standard practice to turn off interior lights upon exiting a room, the same cannot be said for outdoor lighting that keeps a city bright long into the night. Since the late ’80s, the International Dark-Sky Association (IDSA) has been the recognized global authority on light pollution, and in recent years, the organization has set forth a set of standards to guide the lighting industry towards more environmentally-responsible lighting design—Dark Sky compliance.
Artificial Light vs. The Sky’s Natural Rhythm
Artificial light’s effects on the outdoors are far reaching, but can be classified into four main categories:
- Glare: Bright lighting that creates visual discomfort
- Skyglow: Lighting that brightens the night sky in inhabited areas
- Light Trespass: Light falling where it is not intended or needed
- Clutter: Excessively bright and often confusing groupings of light sources
Each of these four categories has their own set of stark effects, from economics and the endangerment and disruption of natural ecosystems to an overall decline in human health.
But first, some statistics.
Eighty percent of the world’s population lives under skyglow. What does the night sky truly look like? For 99% of residents in the U.S. and Europe, the answer is unknown, because the public cannot experience natural light due to excessive and poorly planned outdoor illumination.
Beyond light pollution’s poetic injustice of hiding the night sky’s natural beauty, the effects of glare, skyglow, light trespass and clutter created by artificial outdoor lighting are also economic. During dark hours, 30% of outdoor lighting is wasted, mostly due to lights that are not shielded, contributing to skyglow and light trespass. To counteract the carbon dioxide produced by this wasted light, the planting of new trees—to the tune of 875 million per year—would be required. While 13% of residential electricity is used to power outdoor lighting, a cultural shift to using Dark Sky-compliant outdoor lighting fixtures has the potential to cut energy consumption by 60-70%, according to the IDSA.
Artificial Light, Animals and Humans
For ecosystems, artificial light is a growing and detrimental concern. When the natural rhythm of light and dark is disrupted, simply said, plants and animals become confused. The evolution and sustainability of ecosystems around the world depend on the rhythm of natural light for reproduction, sleep, nourishment and predator protection. When light pollution turns night into day, animal and plant life experiences the consequence.
Rather, consequences. Each year, millions of sea turtle hatchlings die because they can’t find their way to the ocean. The migratory patterns of birds become skewed, and they arrive too early or too late to their destinations, missing the ideal conditions for nesting and foraging—if they don’t first fly off course and collide with a distracting, lit-up skyscraper. The glare from artificial light directly affects wetland habitats, preventing frogs from their nighttime croaking ritual for mating, and reducing their population year by year. While pesky, insects are the backbone of ecosystems around the world. Species rely on these winged travelers for food and pollination, but collisions with artificial lights quickly and permanently end their lives. The chain effect is dramatic and threatening, but stoppable.
Artificial light at night affects human health, too. A contributor to increased obesity, depression, sleep disorders, diabetes, breast cancer and more, artificial nighttime light drastically impacts circadian rhythms, leading to weaker immune systems, higher cholesterol and lower levels of melatonin. Blue light, the most popular color of light for outdoor LED lighting, brightens the night sky more than any other color of light, and its glare reduces visibility, causing accidents that range from a bumped elbow to a hospital stay, and contributes to macular degeneration which can lead to a complete lack of sight.
Let There Be Eco-Conscious Light: Dark Sky Compliant Lighting Solutions
Unlike many other forms of pollution plaguing the planet, light pollution is reversible. According to the IDSA, outdoor lighting should only be used when needed, be no brighter than necessary, minimize blue light emissions and adopt fully shielded light sources as a best practice of outdoor lighting design.
Best practices call for appropriate, place-sensitive light, like incorporating waist-high outdoor lighting fixtures, rather than fixtures that shine down from an unnecessary height and, subsequently, cause light pollution. Though it might be difficult to let night be night when there is still plenty of life that happens after dark, solutions exist that can mitigate the negative effects of outdoor lighting.
Downward Facing Illumination: Shielded Lights
A shielded light directs light downward where it’s needed while preventing light pollution by minimizing glare, light trespass and skyglow. Abiding by Dark Sky standards, incorporating shielded light into outdoor lighting designs lowers energy consumption while increasing the efficacy of outdoor illumination.
Warming Up: LEDs and the Color of Light
Insects aren’t attracted to just any light—they fly toward UV light, so opting for LEDs outdoors can prevent frustrating buzzing when entertaining while also preventing the untimely demise of those insects that do so much to support global ecosystems. LEDs provide bright enough light to ensure outdoor safety, but are also incredibly efficient, reducing energy waste. Dimmable LEDs are doubly successful in maintaining responsible energy consumption.
The downside? LEDs often do produce larger amounts of blue light, which is harmful to nature, wildlife and humans. Opting for low-spectrum LEDs, bulbs with an amber color or lighting that has a color temperature no higher than 3000 Kelvin are forward-thinking ways to contribute to responsible outdoor lighting design.
Waste No More: Dimmers, Timers and Motion Sensors
Remember that 30% of outdoor lighting is wasted during dark hours. Light trespassing onto a nearby property or glaring unnecessarily from a too-bright bulb are avoidable side effects of nighttime illumination. In addition to selecting a bulb no brighter than necessary and turning off outdoor lights when they’re no longer needed, employing dimmers, timers and motion sensors are three ways that can reduce light waste with little more effort than installation and selecting your settings.
As designers become more eco-conscious in their design practices, low-polluting design will become an inherent element of high-quality outdoor lighting. While light pollution is not permanent, its impacts have already been and continue to be felt by ecosystems around the world. By choosing to pursue sustainable lighting systems that support the natural rhythm of light and dark, outdoor lighting designers can encourage and support the repair of healthy ecosystems while contributing to good design that illuminates responsibly.