Light Pollution

What difference do light pollution and dark skies make?

Hot Topic: Dark Skies

Idaho is blessed with spectacular night-sky views in our rural areas. Nowhere is the view better than in Central Idaho. ICL actively worked to get America’s first dark sky reserve designated in Central Idaho to make sure that generations to come will be able to see the same views and to preserve the benefits of dark skies to humans and wildlife. Learn more about the recently designated Central Idaho Dark Sky Reserve and the work behind it.

Light Pollution

New research shows that 80% of the planet’s land areas and 99% of the population of the United States and Europe are under skies blotted by artificial light — in fact, nearly 80% of North Americans can no longer even see the Milky Way.

We’re familiar with the idea of land, water and air pollution but did you know that inappropriate or excessive use of manmade light is considered light pollution?

In addition to obscuring the spectacular night views that inform our sense of place in the universe, the consequences light pollution imposes on us concern ICL.

Forms of Light Pollution

Light pollution can take the form of glare, skyglow, light trespass or clutter. All these sources of light pollution are manmade.

  • Glare: Excessive brightness that causes visual discomfort
  • Skyglow: Brightening of the night sky over inhabited areas
  • Light trespass: Light falling where it is not intended or needed
  • Clutter: Bright, confusing and excessive groupings of light sources

Consequences of Light Pollution

The inappropriate or excessive use of artificial light can have serious environmental consequences for human health, wildlife and our energy grid.

Human health—Exposure to artificial light at night can can negatively affect human health by increasing risks for obesity, depression, sleep disorders, diabetes, breast cancer and more.

Wildlife—Many creatures including amphibians, birds, mammals, insects and plants are affected by light pollution. Artificial light disturbs sleep patterns and interferes with reproduction and reducing populations.

Energy—According to the U.S Department of Energy, about 35% of light is wasted by unshielded and poorly aimed lighting—that amounts to $3.3 billion and 21 million tons of carbon dioxide per year.

How You Can Combat Light Pollution

There are several things you can do personally to help fight light pollution. Here are a few ideas for what you can do around your home, business and community.

1. Inspect the lighting around your home

Poor lighting not only creates glare and light pollution but also wastes enormous amounts of energy and money. Take a few moments to check your property for inefficient, poorly installed and unnecessary outdoor lighting. Learn how by visiting the International Dark-Sky Association’s (IDA) residential and business lighting webpage.

You’ll be surprised how much eliminating or adjusting a few bulbs around your home improves the view. After you have made a couple of changes, take the opportunity to get reacquainted with the nighttime sky. If you’re really interested in preserving our night sky, take a moment and learn about the Central Idaho Dark Sky Reserve.

2. Use dark-sky friendly lighting at your home and business

Look for the International Dark-Sky Association’s fixture seal of approval on any outdoor lighting you purchase. IDA maintains a searchable database of lighting products certified to minimize glare, light trespass and skyglow. Use these products when replacing outdated or inappropriate lighting fixtures.

3. Talk to your friends, family, and neighbors

You can be a powerful dark-sky advocate in your neighborhood, your city, and even your state and country. Solving the light pollution problem involves raising awareness of the issue so that people are empowered to make better decisions as consumers, voters and community members. Use resources like IDA’s general brochure, “Losing the Dark” video, or mobile apps to help spread the word.

4. Advocate for a lighting ordinance in your town

At the heart of reducing light pollution is smart community planning. Numerous cities and counties in Central Idaho already have dark sky ordinances that require shielding of outdoor lighting. But given changes in lighting technology and the recent surge in LED popularity, revisions to many older dark sky ordinances are becoming necessary. ICL has been working with local governments to assess the need for adopting or improving existing ordinances. If you have any questions about this process please email Betsy.

5. Steward the night sky through the IDA Dark Sky Places Program

The International Dark Sky Association’s Dark Sky Places Program started in 2001 to inspire communities around the world to preserve and protect dark sites through responsible lighting polices and public education. There are several different designation opportunities through the program that include

  • International Dark Sky Communities
  • International Dark Sky Parks
  • International Dark Sky Reserves
  • International Dark Sky Sanctuaries
  • Dark Sky Developments of Distinction


ICL has worked closely over the past couple years with the city of Ketchum to help the city qualify as a Dark Sky Community.

ICL worked closely with Central Idaho communities, counties and the Forest Service to secure designation of America’s first dark sky reserve, the Central Idaho Dark Sky Reserve.

Read more about ICL’s accomplishments.