What about light?  Bet that didn't cross your mind, eh?.  And I don't mean the warm, feel-good light from the sun that makes our trees, plants, and flowers grow.  I'm talking about the unnatural, man-made, artificial extension of daylight.  Block after block of super-bright streetlights.  Glowing billboards.  Big box retail outlets with parking lots lit up like the Vegas strip.  Car dealerships with towering mega-watt lamps lighting their sales lots all night long.  Store fronts and businesses with their fancy decor lights blazing long after the end of normal business hours.  Pole lights, yard lights, porch lights, garage lights, and deck lights banishing the darkness from the night.  All of these and more combine to create that ubiquitous orange glow over our cities and suburbs.  It's called light pollution.  This sky glow that vanquishes all but the few brightest stars and planets in the night sky!

Wait!  What?  You didn't realize there was more up there in our night sky that just those few stars?  Oh my, it's worse that I thought!!!  Currently, two-thirds of the US population can no longer see the Milky Way galaxy with the naked eye at night (that also extends to 50% of the European population and one-fifth of the world's population as a whole).  Studies and reports warn than within another quarter of a century, a mere 10% of the world's population will ever see a starry night sky.  So rapid and prolific is the spread of light pollution that we will soon be faced with the reality of a truly 24-hour day.  And it's not just the stark ugliness of this glowing night that is a problem.  Recent studies are showing that the loss of night is taking an actual physical toll on our species and other wildlife.  There is a growing link between constant light at night and increased incidents of diseases like cancer.  It's disrupting our natural circadian rhythm and causing untold physiological problems.  New studies also confirm that nighttime lighting is preventing special atmospheric molecules from doing their job of scrubbing the air clean during the dark of night.  So, light pollution is actually worsening other forms of pollution.  Yet, of all forms of pollution and environmental blight, it turns out light pollution is the easiet to correct.

What can we do about light pollution?  Well, it can start with little steps at home.  Things as simple as turning off lights when they're not needed.  Only turning them on when they are needed.  Only using as much light as necessary when needed.  Ensuring outdoor lights are properly positioned and pointed downward so they only light the intended area rather than spilling up into the night sky, onto neighboring properties or into the windows next door.  Changing out light bulbs for lower wattage, more efficient bulbs.  Replacing glaring outdoor light fixtures with shielded, full-coutoff fixtures.  Installing motion-activated outdoor light fixtures in those areas where it isn't necessary to leave lights on all night.  These are a few of the ways we can help control light pollution at home.

Specifically, I'd like to focus on outdoor light fixtures in this article and the differences between poor lighting choices and responsible lighting choices.  To the right is a product photo of a typical exterior light fixture found on most homes in my neighborhood and throughout the Chicago suburbs.  There are many different designs and variations, but most share the common traits of a bare bulb enclosed within a fixture with clear or transluscent side panels.  Often, these fixtures are illuminated with an incandescent bulb somewhere in the 60-100 watt range.  The problem with this style of fixture is its lack of any kind of directional control of its illumination.  The light spills up into the night sky and outwards into neighbors' windows.  A very small percentage of the total light output actually illuminates the ground in the immediate area of the fixture where it would be most useful.  This type of fixture is wasteful and irresponsible for several reasons: 1) It doesn't focus its light on the intended path of illumination, 2) Due to the wasted light spilling up into the sky and sideways into the neighbors' windows instead of down where it belongs, owners have a tendency to use brighter bulbs to pump more light onto the ground where they want it; 3) It causes "light trespass" where the light shines outside of the owner's property and onto neighboring properties; 4) The bright outward illumination shines directly into neighboring homes possibly angering or frustrating neighbors and putting undue strain on relations; 5) The unshielded bulbs create annoying and possibly unsafe glare for people driving or walking by.

To the left is an example of this type of lighting fixture in use in my neighborhood.  Click on the photo to view a larger image.  Notice the V-shaped shadow the lights cast up the side of the garage indicative of light spilling up into the sky.  Since these fixtures are not shieled in any way and have no cutoff feature, the light spilling out horizontally is very bright and produces a lot of glare.  The lights are very harsh on the eyes when you are looking directly at the garage.  Note how well the flag is illuminated even though the lights are not focused on it.  A clear sign that much of the light is being wasted horizontally.  Unfortunately, notice how little of the total illumination actually reaches the ground of the driveway where it is intended and where it would be most beneficial.  Each of these fixtures is burning a 75-watt incandescent bulb and doing a very poor job of illuminating the necessary area.

When I purchased my home, it had similar style light fixtures installed on the garage and at the front door as those above.  In the summer of 2010, I decided to do my part to reduce unnecessary and wasteful outdoor lighting.  I replaced my fixtures with fully-shielded, full cutoff light fixtures that are approved by the International Dark Sky Association.  To the left is a product photo of the fixtures I purchased.  I picked them up at my local home improvement store for a pretty decent price.  You will note that the fixture has a conical, opaque shield instead of glass/translucent sides.  This both reflects the light downward where it belongs and prevents light from spilling out to the sides.  The light bulb is fully recessed into the housing so that it cannot be seen from above a 75° horizontal line of sight, thus preventing any glare when looking directly at the fixtures.  Because the cone of light is focused downward, these fixtures are much more efficient at illuminating the intended area around them.  Therefore, they can actually use a much lower-wattage bulb to provide the same amount of illumination as the conventional fixtures shown above.  An added benefit of the fixtures that I purchased is that they are both light sensitive and motion activated.  They automatically turn on when it gets dark out and automatically turn off when the sun comes up in the morning.  No more forgetting to turn off the outside lights during the day!  Also, they can be set to only turn on when someone approaches the house rather than remaining on all night long.  A real plus for those who are really enery and budget concious.  Not to mention, I think they are very simplistic and very stylish at the same time!

To the left is a photo of my garage at night with the new fixtures installed.  Click the image to enlarge.  Right off the bat, you'll notice a big difference between these fixtures and the ones pictured above on a neighbor's garage: the light shines down!  The conical shape of the lamp reflects the light downward where it belongs and where it does the job for which it is intended.  The shadows cast by these light fixtures are exactly the opposite of the neighbor's.  There is no light spilling up into the sky or even sideways into the windows of the house next door.  Not only that, but you can't even see the actual bulbs in the fixtures, which means no harsh glare for anyone driving or walking past.  Since all the light is reflected downward, these fixtures properly illuminate the driveway and walkway leading up to the front door without light trespassing onto neighboring property.  Compare the photo of my lighted garage and driveway to that of a neighbor's above.  My shielded fixtures actually do a better job of illuminating the intended areas than the bare-bulb-in-glass fixtures.  In fact, mine would do an even better job lighting the driveway if it weren't for those mondo Canna plants blocking some of the light.  Also, keep in mind, the neighbor's fixtures are using two 75-watt incandescent bulbs.  The fixtures on my garage are using two 9-watt CFL bulbs.  So, that's a total of 18 CFL watts versus 150 incandescent watts burning through the night.  Because these fixtures are so efficient at pointing the light downward, you can do a better job of lighting the area using less energy, which means less $$$ on your electric bill.

So, let's recap.  The next time you're in the market for outdoor lighting fixtures, consider choosing fixtures that are good for the night sky, good for the environment, good for maintaining friendly relations with your neighbors, and good for your utility bill.  Look for full-cutoff, fully-shielded fixtures that cast all their light down instead of up into the sky or out across the street.  Install them correctly and make sure they are properly pointed to avoid any light trespass.  Fixtures that indicate they are night sky or dark sky friendly are best and can be found at your local home improvement stores or ordered online from many different retailers.

Remember, your home can be beautifully, responsibly illuminated and protect our dark night skies at the same time.

Keep a weathered eye for the next article in our "Light Pollution" series where I document and discuss light trespass.

Thank you!  Clear skies!!!