Thinking about light pollution

Let’s quickly review the consequences of light pollution.

Direct glare caused by excess or inappropriate lighting makes it harder to see. Think of how difficult it is to see when an on-coming car fails to dim its brights. Bright light shining directly into the eye causes the pupil to contract, and it can take up to an hour for the eye to recover. While recovering, nighttime vision is greatly impaired. It is helpful to keep in mind that the eye always adapts to the brightest object in the field of view. When the brightest object is the light fixture itself this causes everything else to appear darker than it truly is.

Migrating birds are disoriented by bright lights. Hundreds of species of birds migrate at night. But brightly lit structures, or spot lights aimed to the sky, can confuse the birds, drawing them towards the light, often resulting in collision with buildings, towers or other tall, illuminated objects.

Energy is wasted. By having bright lights spreading light pollution all night long, billions of dollars are wasted each year by homeowners and businesses.

Neighbors are annoyed. A bright light shining into the bedroom at night is the classic example of neighborhood light pollution.

And, light pollution makes it hard to see the stars in the night sky.

There are several simple, inexpensive steps that everyone can take to reduce light pollution.

First, a homeowner can stand at the edge of her property and check to see if she can see any lightbulbs. If so, then she is contributing to light pollution in her neighborhood, but a few simple changes will fix the problem.

Shield the bulb/point floodlights towards the ground. By directing light towards the objects it’s intended to illuminate, people will avoid something called “light trespass,” or light leaving the property and trespassing onto someone else’s. Sensible lighting also means that lights are directed towards the ground, not up into the sky or out into space.

Reduce the wattage. A 40 watt incandescent (or 11 watt compact fluorescent) bulb is bright enough for a front porch light.

Attach a motion sensor. This is by far the best application of security lighting because when a light turns on suddenly it immediately attracts the attention of everyone within its field of view. Police and security personnel are drawn to investigate an area usually dark where sensors have triggered the lighting.

Lights off after 10pm. Most people are at home and in bed (or getting ready for bed) by 10pm, making “decorative” lighting an unnecessary waste of energy. This is also the time when excessive lighting is most likely to affect migrating birds.

Talk to the neighbors. After a homeowner gets his or her lighting in order, it is time to approach any neighbors who are causing light pollution. Explaining the steps taken at ones own property, and emphasizing the energy savings is probably the best way to start the conversation.

Maybe the neighborhood can hold a star gazing party once the light pollution is gone!