Let there be Dark!
Jil Swearingen
The Milky Way is a candy bar. It’s also the galaxy that contains our Solar System. Most people living in or near cities never see the Milky Way or most stars and planets because of light pollution. For billions of years, until the advent and widespread distribution of artificial lighting, the Earth and all its organisms experienced dark at night and light during the daytime. Light pollution is a fairly recent phenomenon resulting from too much light being emitted and scattered into the sky by billions of lights around our homes, offices, shopping centers, ball fields, streets, highways, and the myriad of other developed areas.
Artificial lighting is essential to our modern way of life. However, we can significantly reduce light pollution through the use of lighting approved by the International Dark-Sky Initiative (IDA) including shielded light fixtures, energy-efficient lights (e.g., light-emitting diodes or LEDs) of reduced intensity (brightness), appropriate color wavelength, and motion-detection activated lights. In addition to impeding our view of the night sky, light pollution poses threats to wildlife and ecosystems, human health and safety. The IDA strives to educate the public and policy makers about the harms posed by light pollution and advocate for improved lighting everywhere with the goal of improving lighting in our environs and making our night sky visible again.
Impacts to wildlife and ecosystems. There are some known and many more unknown ecological impacts of artificial lighting. Many species of insects, from giant silk moths to mayflies and many beneficial insect species, are drawn to bright lights at night and once drawn to the light, they become mesmerized and, rather than finding mates and reproducing, they end up dying at the light. Excessive lighting along coastlines has led to the death of baby sea turtles who run towards the artificial lighting rather than the ocean after hatching. Migrating birds evolved to rely on the night sky to direct their annual migrations are distracted and confused by the abundance of artificial lighting along their migration routes which can be fatal. The reproductive activities of frogs are also impaired by artificial lighting around wetlands.
Safety. More light is better for safety, right? Not really. Improper lighting at night can cause “disability glare” which is when light enters the eye and impairs the ability to focus on objects. Studies have shown that the best lighting to protect you and your property is motion-activated lighting that comes on when a visitor or intruder enters an area and then goes off after a period of time. Flooding your property with excess light has actually been shown to help criminals see your property. If it was dark, a criminal’s presence would be visible when he/she turns on a flashlight.
Human health. Health impacts of excessive nighttime lighting include alteration of natural biological rhythms (Circadian Rhythm), reduced sleep time, dissatisfaction with sleep quality, nighttime awakenings, excessive sleepiness, impaired daytime functioning, and obesity. The American Medical Association assessed studies that showed that exposure to blue-rich white light at night was associated with increased risks for cancer, diabetes and cardiovascular disease. Because blue-rich white LED street lighting was found to be five times more disruptive to human sleep cycles than conventional street lighting and brighter residential nighttime lighting is associated with reduced sleep, impaired daytime functioning and a greater incidence of obesity, the AMA encourages attention to optimal design and engineering features when converting from existing lighting technologies to LED. These include requiring properly shielded outdoor lighting, considering adaptive controls that can dim or extinguish light at night, and limiting the correlated color temperature (CCT) of outdoor lighting to 3000 Kelvin (K) or lower.
Energy wasting. Lighting that is excessive for an area, is too bright, emits light into the sky, or shines when and where it’s not needed is wasteful. Wasting energy has huge economic and environmental consequences. 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!
What we can do. Environmental responsibility, 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, with less energy and reduced expense.
· Unnecessary indoor lighting – particularly in empty office buildings at night – should be turned off.
International Dark-Sky Association resources and new lighting technologies can help conserve energy.
· 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.
· 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. Watch a clip of the documentary The City Dark to learn how lighting design can reduce light pollution and also conserve energy.