By Kim Robson
None of us tolerates environmental pollution anymore. We’ve worked so hard for clean air, clean water, and healthy ecosystems; yet, a terribly destructive polluter is at work in every industrialized part of the world, and hardly anyone notices.
I am talking about light pollution. The International Dark-Sky Association (IDA) defines light pollution as the alteration of light levels in the outdoor environment (from those present naturally) due to man-made sources of light. Any negative effect of artificial light including sky glow, glare, light trespass, light clutter, decreased visibility at night, and energy waste are considered to be light pollution.
Light pollution goes hand-in-hand with industrial civilization. It comes from building exterior and interior lighting, advertising, commercial properties, offices, factories, streetlights, and illuminated sporting venues. Highly industrialized, densely populated areas are the most severely affected. City dwellers never see more than a handful of stars (I was nine years old before I saw the Milky Way). Light pollution interferes with astronomical observations, disrupts ecosystems, and has adverse health effects. There are two main types of light pollution: light that intrudes on an otherwise naturally dark or low-light setting, and excessive light (generally indoors) that leads to discomfort and adverse health effects.
“Skyglow” describes the eerie glow effect visible over populated areas. All the excess light that is escaping into the sky is then being scattered by the atmosphere back toward the ground. For instance, you can see the glow from Las Vegas as far away as Death Valley, a hundred miles away.
Medical research shows that excessive light on the human body causes a variety of adverse health effects. Many lighting design textbooks use human health as an explicit criterion for proper interior lighting. Over-illumination and improper types of light can compromise health, resulting in headaches, fatigue, stress, decrease in sexual function, and increase in anxiety. Lab animals exposed to unavoidable light have had negative effects on mood and anxiety. Exposure to constant bright light is considered a very simple and effective torture technique.
In Blinded by the Light? (2009), author Professor Steven Lockley of Harvard Medical School states that the human health implications of light pollution are great, and that “light intrusion, even if dim, is likely to have measurable effects on sleep disruption and melatonin suppression. Even if these effects are relatively small from night to night, continuous chronic circadian, sleep, and hormonal disruption may have longer-term health risks.”
The effects of light pollution on the environment are well-documented. Artificial light disrupts nocturnal plants, animals, and flying insects. Tall lighted towers and buildings, and offshore oil drilling platforms can throw off critical navigation for migrating birds and turtle hatchlings. Light pollution can even cause physiological harm, leading to developmental problems and mutations, and altering predator/prey interactions. It’s even believed to alter the zooplankton in lakes, causing unnatural algae blooms.
Even here in the mountains, living off the electrical grid, no less, we still see people burning their unshaded outdoor lights all night, every night. Some do it out of misguided notions about security. I suspect the real reason may go deeper than that. As children, we worried about monsters or boogeymen in the dark. As adults, we still cling to those silly fears, burning far more lights than we need.
What can we do to help bring back the dark? First, install “full-cutoff” fixtures on your outdoor lights. They are very effective in reducing light pollution by not allowing light to shine above the horizontal plane. The light is being directed downward, where you want it, not out into space. Municipalities can install low pressure sodium streetlights. They reduce glare and skyglow, and are better for those with night-vision problems. Opponents of sodium lights hysterically claim they increase crime rates, but that has never been proven.
Most light pollution can be reduced by simply turning off unneeded outdoor lights. Timers are especially valuable for this purpose. We should be lighting up stadiums only when there are people inside. Participate in World Lights Out events, which encourage turning off the decorative lights of public buildings and bridges for one hour. Instead of practicing Lights Out only once a year, and for only one hour, why not try it every night?