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Preserving Our Dark Skies

500px Photo ID: 28041007 - Salt Lake City from Ensign Peak

By Colin Green, SLCgreen Fall Intern

Can you remember a time when you lay on the ground under a cloudless night gazing up towards the heavens, making wishes on shooting stars? Have you ever done this within the city? Probably not, because of light pollution.

Humans have lived with dark starry skies for most of our history. This connection to the celestial bodies has helped guide the natural rhythms of our bodies, but recently, in tandem with rapid urbanization, dark skies are disappearing from our lives. Light pollution is taking overnight skies across the country, but it doesn’t have to.

Light pollution comes in a few different varieties that affect us and our environment differently. The first form is called SKYGLOW and it is what usually comes to mind when thinking about light pollution. This is the light that is projected towards the sky creating an illuminated dome in urban areas around the world (80% of World Population Lives under Skyglow).


The next is GLARE. This is caused by unshielded lights shining directly in your eyes. A good way to think of this one is a car driving at you with their high-beam lights on.

The third type of light pollution is called LIGHT TRESPASS. This happens when an unshielded light shines into an area where it is not intended. A neighbors light shining through your window is a great example of this.

Fortunately, with more thoughtful lighting these forms of light pollution can be avoided. This has positive effects on human health, safety, the environment, and energy efficiency.

Human Health

  • Proper lighting positively affects human health by not disrupting our natural circadian rhythms.
  • Artificial light can reduce the body’s natural production of Melatonin, causing a number of health risks.


Energy Efficiency

  • 30 percent of all outdoor lighting in the U.S. alone is wasted.
  • Installing quality outdoor lighting could cut energy use by 60–70 percent, save billions of dollars and cut carbon emissions.
  • LEDs, compact fluorescents (CFLs), dimmers, motion sensors, and timers can help to reduce average illumination levels and help reduce energy use.

While Salt Lake City does not yet have a citywide dark skies lighting ordinance, we’ve begun implementing best practices in retrofitting public street lighting. Our internal Sustainability Policy also calls for using the International Dark-Sky Association and the Illuminating Engineering Society of North America’s Model Lighting Ordinance as a guide whenever practicable when upgrading exterior lighting in order to provide effective and safe outdoor lighting while conserving energy.

Here’s how you can help (recommendations pulled from University of Utah Department of City and Urban Planning):

  • Only use lighting when and where it’s needed
  • If safety is concern, install motion detector lights, dimmers, and timers
  • Properly shield all outdoor lights
  • Keep your blinds drawn to keep light inside

Fortunately, here in Utah, we can all make a difference.  And we’re lucky to still have access to many dark skies, with nine certified dark sky parks spread out across the state. While the dark sky resource remains, it is something that could be lost if they aren’t valued as our city and state grow. To value darkness, is to understand its benefits and how to protect it.


2 Comments Post a comment
  1. Jim Webster #

    All of your points are noted. However, what strikes me as unfortunate is the city’s failure to adequately support the Yalecrest Neighborhood Council in our effort to preclude, or at least define a plan to mitigate light pollution from the university’s Rice-Eccles stadium, Rowland Hall St Mark’s soccer field, the 5 softball diamonds in Sunnyside Park managed by Salt Lake County, and East High School’s football field. In all cases, lights are incessantly impacting neighbors when NO athletic or spectator activity is occurring.
    Additionally, the uuniversity remains adamant in its plan to convert a baseball practice facility on Guardsman Way into a stadium with lighting in close proximity to residents. To date, the city has done nothing other than refuse a land sale, even though the mayor and council have approved and endorsed the new East Bench Master Plan that prohibits light pollution from such facility. It appears SLC Green and the city administration are at significant odds with each other, if not demonstrating a classic example of hypocracy that continues and may intensify light pollution, a public health impact.

    December 28, 2017
  2. Diana Torres #

    I really agree with you. Light pollution is terrible around Salt Lake in general. I live on the west side, and here sometimes it is too dark, if you consider the people walking in the dark places where drivers still drive like it’s daytime bright.
    D. Torres

    January 5, 2018

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