Outdoor Lighting

Above are Pacific swordferns (Polystichum munitum) dusted by snow in a stand of epiphyte-covered bigleaf maples (Acer macrophyllum) in Oregon's West Cascades.

ARTIFICIAL LIGHT AT NIGHT:  A PERVASIVE PROBLEM

 

 

A LITTLE HISTORY

 

Every organism that ever evolved on this planet, from the most minute zoöplankton in the sea to the mighty elephant, evolved in the absence of light at night.  Except for moonlight and campfires—after humans domesticated fire a few hundred thousand years ago—every night there ever was, for nearly four billion years, had been a dark night.

 

That all changed quite recently with the development of the first commercially practical incandescent electric light bulb by Thomas Edison in 1849.  Since then, the proliferation of light at night has been nothing short of explosive, with devastating ecological and physiological consequences for the living organisms exposed to it, including humans.

 

 

PROBLEMS CAUSED BY OUTDOOR LIGHTING

 

Only in the past few decades have researchers begun to examine the nefarious effects of artificial light at night (or ALAN).  From deciduous trees “confused” by streetlights and reluctant to lose their leaves in fall, to moths which are completely disoriented by ALAN and unable to either feed or breed because of it, to significantly higher breast cancer rates in women who work nights, the message is clear:  we humans have created yet another disturbance of the natural world, the ramifications of which we never envisioned and only now are beginning to understand.

 

A satellite photograph of Earth at night reveals the scale and the severity of the problem.  In the U.S., truly dark areas are few and far between, and most of them are very small.  Perhaps the largest dark area at night in the 48 contiguous states extends from southeastern Oregon into northern Nevada.  Even the smallest urban area is identifiable by its nighttime light glow, as are the highways strung with lights that connect urban areas.  And large metropolitan areas, from the Los Angeles basin to the Northeast corridor between Washington, D.C. and Boston, are vast pools of light.


These absolutely awful lights were installed by the University of Oregon in November 2021 along a riverside multi-use path that winds through a natural (!) area.  The unshielded and harsh white lights are visible more than a quarter of a mile away--and even across the river in a formerly dark riparian woodland--and actually threaten rather than enhance the safety of path users due to the disabling glare they create.  Moreover, the glare of the lights is exacerbated in wet weather when it assaults path users both from above (the light itself) as well as from below (reflecting from the wet pavement).

BRINGING BACK THE DARK

 

Given the extent of the problem, it might seem like a hopeless dream that night skies will ever again be dark.  But just as this proliferation occurred one light at a time and over a matter of decades, so can we restore the darkness that we all need—one light at a time.

 

Communities across the U.S. and elsewhere are recognizing the problems created by ALAN and beginning to address them.  Here in Eugene, our land use code—which applies to all private property—contains a section called Outdoor Lighting Standards.  The standards do not outright forbid ALAN, but simply require all light fixtures to be shielded so they don’t cast light off the property on which they’re installed, nor up into the night sky.  Regrettably, there is much misunderstanding and almost no enforcement of our community’s well-intentioned outdoor lighting standards, and code violations are the rule, rather than the exception.

 

For the good of all of us, it would be wonderful if nighttime lighting were extinguished altogether.  Rather than communities and businesses providing street, park, and parking lot lights that are on all night long—and homeowners lighting the outside of their residences from dusk to dawn—individuals who want light at night would need to provide it themselves, from headlights on their cars (which fortunately do not project light up into the sky, although they do create an enormous amount of light “trespass” and pollution) to personal flashlights for navigating sidewalks and other outdoor areas at night.


What was once an obnoxious bare-bulb porch light on the front of this house has been inexpensively transformed into an environmentally friendly light by shielding it with a piece of aluminum flashing which was painted matte-black inside and out.  It shines light only where it is needed: down onto the porch, and a gentle glow up to the small porch roof (but not into the sky).  The light source is a tiny 15-watt incandescent bulb.  Of course, it's also turned off after 9 p.m. most nights, which simply adds to its environmental-friendliness!

WHAT YOU CAN DO

 

Although dramatic changes in how we collectively view ALAN and address its proliferation are unlikely anytime soon, there are many simple things that individuals can do in the meantime to help reduce ALAN.  Here are a few of them:

 

·       Turn off all outdoor lights after, say, 10 p.m. every night.  (Research shows that lighting your property does not increase security; instead, it just makes your belongings easier to see, and allows prowlers to more easily move around your property unnoticed, because they're not waving flashlights around.)

 

·       Replace 100-watt (or brighter) bulbs in outdoor light fixtures with lower-wattage bulbs; a 15-watt bulb can very satisfactorily illuminate an outdoor area at night, and even 4-watt “night lights” can provide adequate light along, for example, a walkway up to a house.

 

·       Install motion sensors on all outdoor lights so they come on only when someone passes nearby, then shut off one or two minutes later.

 

·       Shield your existing, non-compliant outdoor lights with exterior housings—of wood, metal, plastic, or even aluminum foil—to eliminate “light scatter” from the fixture, and make the light shine only downward where it’s presumably needed.

 

·       And look at the lights inside your house; are they shining out your windows and into the street or into a neighbor's bedroom?  If so, replace them with better designed fixtures that keep the light where it belongs.

 

In addition, you might post a little sign on your property that explains what you’ve done and why, and encourage your neighbors to follow your example.  Again, one light at a time, we can reduce the effects of ALAN and begin to restore a healthy night-time environment—one that is not polluted by light—for our own good as well as for the good of the rest of the natural world.


(This page updated 28 May 2023.)