Light Pollution

Environmental Problems

Human beings naturally derive their sleeping and waking schedules based on the rising and setting of the sun. For wildlife, too, natural rhythms and activities are tied to sunlight and darkness. Excessive light at night interferes with many necessary activities for wildlife Nocturnal creatures, in particular, are at risk because they no longer have the cover of darkness to protect them from predators or the natural signal that it is night and time to become active.

At the same time, much of the artificial light is not used for any purpose. Roughly one-third of all light pollution is wasted energy, which uses up 30 million barrels of oil and 8.2 million tons of coal each year at a cost in the United States about $2 billion, according to the International Dark-Sky Association. In addition, the oil used emits nearly 14.1 million tons of carbon dioxide (CO2) into the environment, which contributes to global warming.

Light Trespass

Light trespass is a form of light pollution that occurs when artificial light interferes with a person's normal dark cycle. Bright days and dark nights are essential for proper sleep cycles. For instance, streetlights or car headlights that spill over into one's backyard is considered light trespass. To combat light trespass, it is ideal to have artificial street lighting specifically directed at the roads, not at the surrounding residences.

Glare is a form of light pollution that directly impacts a person's eyes. This is regarded as the most dangerous side effect of light pollution. There are three different types of glare: blinding glare, which is so severe that the eyes cannot adjust to the darkness for some time even after the light source is removed; disability glare, which reduces visual performance; and discomfort glare, which, although it may not interfere with person's performance, creates annoyance and distraction. Discomfort glare is common for drivers on roads where they are not protected from the headlights beaming from cars traveling in the opposite direction at night.

Another form of excessive artificial light is referred to as clutter. When too many lights are placed in one location, the result is not better visual acuity but cluttered light, which is highly distracting, especially for drivers. Human eyes naturally adjust to low lighting and generally adapt well to dark areas. However, overly bright and abundant light prevents eyes from naturally adapting, so that dark areas adjacent to brightly lit areas are nearly impossible to see. Driving along unevenly lit roads at night, therefore, is especially dangerous.

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