Is your Light Trespassing?

This article by Michael Figura was first published in the New Life Journal.

When most people think of pollution, many things come to mind- oil spills, garbage, smog, light pollution.  Light pollution?  As if CO2 was not far-fetched enough, what in the world are those tree-hugging hippies calling pollution now?

According the International Dark-Sky Association, a non-profit dedicated to protecting the nighttime environment, artificial light can cause light pollution by having adverse effects such as sky glow, glare (a blinding effect caused by stray light that reduces the visibility of the target), light trespass (unwanted light that shines onto your property), light clutter, decreased visibility at night, and energy waste.

On January 4th, 2008 the President of the International Dark-Sky Association wrote a letter to the Environmental Protection Agency requesting that light pollution be recognized as an EPA pollutant.  A portion of the letter, which is posted on the International Dark-Sky Association website (, is given below:

“Based on our [International Dark-Sky Association] calculations, we estimate that several billion dollars are wasted each year in the USA due to over-lighting the night. We estimate that about 38 million tons of carbon dioxide are generated by this wasteful practice.

Poor quality nighttime lighting is the main cause of this problem. Such obtrusive lighting causes blinding glare and light trespass. It reduces visibility, rather than enhancing our nighttime environment. Glare, for example, is a particular problem for our country’s aging population. In addition, we are denied access to the beauty of our night skies; which for generations has influenced much of the world’s science, literature, art, and music.

In addition to these problems, wildlife can be harmed by excessive lighting. Migrating birds become disoriented, and sea turtles (all species of which are threatened or endangered) are losing nesting areas due to brightly lit beaches. In addition, recent research has shown a link with melatonin suppression and human health. Lights at night stop humans from producing melatonin, which disrupts our circadian rhythm [A 24-hour cycle in the processes of living beings that is linked to the light-dark cycle]. Melatonin suppressed blood has been shown to cause increased cancer growth rates in laboratory animals.

By promoting responsible outdoor lighting, we can reduce energy waste, control glare, stop most of the obtrusive light trespass, improve visibility and safety, protect biodiversity, live healthier, and preserve. the beauty of our night skies.”

Responsible outdoor lighting does not mean zero lighting.  Outdoor nighttime lighting has its place, especially where safety and security are concerned.  Rather, responsible outdoor lighting has to do with the intensity of the light used and the direction that the light shines.

What can we do as individuals and as community to minimize light pollution, improve our nighttime sky and reduce unnecessary energy consumption?  Here are a few suggestions:

  • Use outdoor light at night only when and where it is needed and at appropriate lighting levels.
  • Use fully shielded fixtures- fixtures that do not allow stray light to shine upwards or sideways.  An example of the impact that fully shielded fixtures can have on reducing light pollution can be seen when driving on Interstate 240 and comparing the Asheville Mall’s parking lot lighting to Wal-Mart’s parking lot lighting.  The City of Asheville had Wal-Mart install fully shielded light fixtures as part of Wal-Mart’s zoning approval.   For more information on light fixtures that are approved by the International Dark-Sky Association, visit and click on “Approved Fixtures”
  • Aim outdoor light fixtures downwards and pay careful attention to ensure that the light does not shine across your property boundaries.
  • Use light efficient fixtures.
  • Incorporate timers and sensors to shut off lights when not needed.
  • Ask our local governments to pass and enforce lighting ordinances as part of their land development ordinances.  The benefits of reducing light pollution are the greatest when the community as a whole takes action.

While being in the middle of the city and gazing at the stars sounds far fetched, the Planning Director of Flagstaff, Arizona told me (a city with a strong lighting ordinance), “it is amazing to walk out of my front doorstep and see the constellations.”