More often, light pollution results from lighting structures that direct light poorly, usually to the extent that less than half of the light emitted is used for the intended purpose of illuminating a particular object or patch of ground. Remaining light is wasted, usually radiating into space, illuminating unintended areas, or casting glare that interferes with night vision and surveillance.
Wasted light means wasted energy, which means a U.S. artificial lighting carbon footprint equivalent to 9.5 million cars and energy cost of $7 billion that could be avoided along with other unsustainable consequences if only efficient lighting strategies were in place.
There are profound astronomical and social consequences of light pollution. For example, light pollution causes the astronomical phenomenon known as “sky glow,” where the sky is washed out and stars rendered invisible from light that is radiating into the atmosphere. Less than 1 percent of humans live in areas where true darkness occurs at night.
People who live in inner city areas often have lower socioeconomic status and encounter more crime on average than people living elsewhere in a city, and it is also in these areas that sky glow is at its most severe. Children confined to inner city areas often grow up without ever seeing stars, let alone other components of the natural world, which is a problem known as “nature deficit disorder.” Therefore sky glow can be an indicator of overarching equity issues and can contribute to unsustainable life styles.
Light trespass can also interfere with biological processes in humans and ecosystems. For example, artificial illumination can interfere with food collection and reproduction in nocturnal organisms such as bats, owls, moths, spiders, crickets, fireflies and frogs. Artificial light has also been known to stunt growth and development in the young of these creatures.
Artificial lights can attract and become death traps for creatures that depend on the light of the moon for navigation, including moths and baby sea turtles. In addition, the intensity and type of light can disrupt circadian rhythms in both diurnal and nocturnal creatures. Bird calls and migration patterns are affected by disrupted circadian rhythms, and increased mortality usually results.
Humans’ melatonin production is affected by disrupted circadian rhythms, which can lead to increased risk for cancers and cardiovascular diseases. Even plants’ photosynthetic machinery can be impaired through disrupted circadian rhythms, causing physiological stress and deformities.
Light pollution is clearly detrimental to the economic, environmental and equity pillars of sustainability, though it receives less attention relative to other forms of pollution. Therefore, it is important to increase awareness of light pollution for the purpose of valuing and promoting healthy and sustainable lifestyles and reductions in nature deficit disorder.
Individuals, businesses and communities should be able to reduce light pollution by making educated decisions about how to illuminate areas. Examples include considering optimal fixture designs, locations, and numbers and judging if it is truly necessary to keep certain fixtures, such as porch lights or building signs, burning from dusk until dawn.
Reductions in crime, biological harm and energy costs can follow from utilizing the most efficient structures that accommodate night vision and circadian rhythms and direct light appropriately instead of indiscriminately emitting intense and unshielded light.
Amy Adams is a member of the UNM Wilderness Alliance.
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