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With a subject such as light pollution it is probably best to answer a couple of questions first. What is light pollution? By definition, light pollution is excessive light or light that blocks our view. In addition, light pollution is produced by humans. Why does it matter? When there is too much light from streetlights, night lights on individual property and so on, it is more difficult to look up and see the stars in the night sky.
Keep in mind, there is more. This excessive light can be a problem both indoors and outdoors. Too much light can also be a problem in a home or work space, because excessive light can be uncomfortable and even have adverse health effects. Both types of light pollution are expensive because we are paying for light that really does us no good. Some groups suggest that as much as 50 percent of the light we have indoors is never efficiently used. Much of this loss of light comes from lights that “leak” their light upward or away from the place where work is being done. Incandescent bulbs, the kind most people use out of habit, are actually inefficient when compared to low pressure sodium lights. Now, some people define light pollution or bad lighting as the light that shines not only on your property but also on your neighbor’s property. In addition, many night lights and pole lights installed for security reasons “leak” upward, obstructing the view of the sky on a clear night. Many of the standard street light designs we are familiar with leak as much as 50% to 70% of their light upward, where it does no good for security purposes. This problem can be reduced by use of the box-style street or pole light with a receded bulb. According to some studies, this design directs almost 100% of the light downward. Some cities have started to use only “full cut-off” lights for parking areas and streets. Early experience has shown that no light is lost above the horizontal line of the shade or shell. In fact, a group called the International Dark Sky Association makes recommendations for “dark sky friendly” lights that direct 100% of the light downward or in a specific direction. With this, energy costs are reduced and the night sky stays naturally dark. These specially-designed fixtures range in price from about $60 for basic models to about $300 for more elaborate, decorative styles (including a wide range of outdoor lanterns). As you can see, light pollution is actually a very important subject that needs to be better understood. |
Lighting Types and Bulbs