Can you remember the last time you saw a dark night sky, full of stars and planets, in vivid detail? For many of us living in the world’s cities, the answer may be “no” or “never.” When we think of pollution, we don’t often think of the lights that line our streets and illuminate our buildings. This week is International Dark Sky Week, so let’s dive into some related questions: what is light pollution, what are its effects, and how can we manage it?
Light pollution is “light from cities, vehicles, etc., that makes it difficult to see things in the sky (such as stars) at night.”[i] Too much nighttime light can disrupt bird migrations and sea turtle hatchings, cause glare and accidents for motorists and pedestrians, and disrupt the circadian rhythms that regulate our sleep cycles and produce hormones that protect us from disease. Research suggests that artificial light at night can negatively affect human health, increasing risks for obesity, depression, sleep disorders, diabetes, breast cancer and more.[ii] From a sustainability perspective, excessive or unshielded lights waste both energy and money.
Image credit: I.D.A.[iii]
The good news about light pollution, in contrast to many other forms of pollution, is that it is immediately reversible. With smart lighting design and turning off unnecessary lights, we can darken our skies and return to a vista full of stars. Here are some tips on reducing light pollution from the International Dark Sky Association:
To minimize the harmful effects of light pollution, lighting should
· Only be on when needed
· Only light the area that needs it
· Be no brighter than necessary
· Minimize blue light emissions
· Be fully shielded (pointing downward)[iv]
Metro’s Historic Courthouse Dark for Earth Hour 2018
Here at the Department of General Services, we do our part to reduce light pollution and eliminate wasted energy. The Department manages nearly 100 city buildings. In each, we strive to ensure that building lighting follows an occupancy schedule and that only necessary lights are on at any given time. Our 21 LEED® certified buildings have automated lighting systems that ensure lights turn on and off at set times. Most of the Department’s buildings are not occupied at night, which means their non-essential lights are turned off to reduce light pollution and save energy.
By being aware of light pollution and the simple, commonsense actions we can all take to reduce it, together we can begin to reclaim Nashville’s night sky.