Shining a Light on Light Pollution

Posted by Lisa Carey

The who, what, when, where, why and how of light pollution and what we can do about it to save energy, the environment and maybe even a little sleep.

You’re probably familiar with air pollution, water pollution and even noise pollution. But are you familiar with light pollution? Let’s take a look into the dark side of light pollution to see why you should care about light pollution and to find out what you can do to reduce it.
When does light become light pollution?
When light goes where it is unneeded or unwanted, it becomes light pollution. Light pollution is sometimes referred to as “light trespass” or “”sky glow.” Satellite images of Earth at night show a tremendous amount of wasted artificial light from cities and roads leaking up into the sky.
What are the major causes of light pollution?
Any outside light sources that allow light to go upwards beyond where it is needed is a contributor to light pollution. There are four categories of light pollution contributors.
1. Unnecessary lights
These lights have no purpose or a turned on when not needed.
2. Excessive lights
This refers to areas with more lights than are needed or lights that are too bright.
3. Badly designed lights
These lights are designed without proper shielding.
4. Badly installed lighting
Sometimes reasonable lights are simply misplaced or misaimed.
Older street lights, illuminated signs and buildings, dusk to dawn lights can all be sources of light pollution that can contribute to the sky glow.
One of the common excuses for excessive lighting is that it is security lighting. So far there has been no proof that this wasteful lighting has reduced crime. Independent studies show that the “fear” of crime is reduced, but actual crime is not reduced by security lights. Lighthouses, which need to be seen from miles away, use less wattage than those used for security lights. This phenomenon of over kill isn’t limited to cities to and urban areas. In some rural areas, 500-watt “Rottweiler” lights wink in the night sky, emitting light far beyond the area that needs to be lit.
Why should we care about light pollution?
Light pollution from artificial sources blocks out the natural lights in the sky. Light pollution doesn’t just affect astronomers and stargazers. The night sky has both national and educational offerings, as well as being a scientific resource.
Light pollution affects everyone. Not just because it is a nuisance but also because it strains our energy systems and wastes natural resources. It also results in wasted money out of our pockets. In fact, a recent study in the United States indicated that over $2 million worth of electricity is wasted each year as it goes upwards and becomes light pollution.
Humans are naturally nocturnal creatures. Excessive light pollution can affect human’s sleep and health. Here’s one example: A gentleman who lives several acres away from a business found himself unable to sleep after the business installed a large light to shine on their American flag at night. It may seem a patriotic or lovely thing to be able to see the flag at night, but it is simply unnecessary for it to shine all night long. A timer that allows that light to shine from dusk until a reasonable time at night would be a simple and energy efficient compromise. It has been said that fences make good neighbors. Light shields and eco-friendly lighting can make good neighbors as well.
Does light pollution affect plants and animals?
Yes. Deciduous trees that are subjected to artificial light will often keep their leaves through winter, disrupting their natural, healthy cycle. Studies have shown that birds can suffer from premature migratory habits because of light pollution. Insects and nocturnal creatures are also confused and affected by excessive, wasteful lighting. Whenever humans disrupt the natural cycles of nature, we can be sure that the impact on our environment will be negative.
Can you make a difference?
Yes. In the same way that individuals and businesses can make positive green impacts through recycling, reducing, and reusing other resources, you can also reduce light pollution. Simple eco-friendly steps can be taken. These include using low-energy bulbs, fitting lower wattage lamps, using light shields, and of course switching lights off when they are not needed. If your home or business uses exterior lighting, consider these questions that can help you reduce light pollution, go green and sometimes save money too.

• Can the light be aimed so that it shines down where it is needed?
• Can it be aimed so that light does not encroach onto a neighboring property?
• Can it be aimed so that it does not “blind” people, especially drivers?
• Can the light be shielded with a better fixture to prevent light escaping to where it is not wanted?
• If the light is correctly aimed and shielded and is of sensible power, does it need to be lit continuously?
• Can you use a timer to reduce the time exterior lights are lit?
• Can you use a motion detector and a timer if the point of the light is “security”?
• Could a 50 watt bulb replace a 100 watt bulb (less wattage for larger wattage bulbs?
• Could a light shield be added to filter light?

The best way to reduce light pollution is to educate yourself and others about the causes, impact and prevention of light pollution. Artificial light is an amazing invention that has many benefits. However, when it is unneeded or excessive, it becomes a nuisance, a waste of energy and money, and has a negative impact on plants, animals and humans.

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