Light Pollution: The Overuse & Misuse of Artificial Light at Night

"Dark sky" does not mean "dark ground"; if you're smart, you can have a dark sky without losing light on the ground.

What is Light Pollution?

Out of all the various pollution humans create, light pollution gets the least attention. But light pollution is one of the most prevalent issues facing the developed and developing worlds today. Light pollution can come in several forms: light trespass is when unwanted light escapes from one property into adjacent properties; over-illumination is using excessive light where it isn't needed; light clutter is the redundant clusters of lighting found in many urban centers; sky glow is the collective light pollution found over big cities. It is an enormous waste of money, of resources, and more importantly, it is harming us.

What Causes Light Pollution?

Light pollution is largely the effects of bad lighting design, which allows artificial light to shine outward and upward into the sky, where it's not wanted, instead of focusing it downward, where it is. Common sources of light pollution include street lamps, parking lot/shopping mall lights, exterior lights found on most homes/businesses, neon signs and illuminated signboards.?

Effects on Human Health

Darkness is essential to our biological welfare. For centuries before the development of artificial light, human beings had become used to a day/night cycle of 12 hours of natural light and 12 hours of darkness. That cycle is a part of our circadian rhythms, an essential biological imperative which is dramatically affected by the presence of light at night.

Disruption of the circadian rhythm has been linked to sleep disorders like insomnia and delayed sleep-phase syndrome, as well as depression, hypertension, attention deficit disorder, obesity, diabetes, and heart disease.

Another important biological function that is disrupted by the presence of light at night is the production of melatonin. Melatonin is a potent antioxidant, anti-carcinogen, and is responsible for regulating metabolism, and immune responses. Lowered levels of melatonin have been shown to have correlation to the rising rates of breast cancer amongst the developed world. According to another study, cited in the journal Environmental Health Perspectives, women who live in areas where it is bright enough to read a book outside at midnight had a 73% higher chance of developing breast cancer than women living in less brightly lit areas.

Does More Light Make You Safe?

Look around at the kinds of lights used at night. Do you have good visibility around you or does the unshielded light produce so much glare that you in fact have poor visibility? It's typically the latter. The safety-related dangers that come with poor visibility at night are caused by glaring lights. But there are easy solutions: shielding lights to reduce glare, dimming lights to provide the right amount of light, and turning off lights when they’re not needed. More light doesn't make us safer, smarter use of light does.

Effects on Wildlife

But humans aren't the only creatures affected by light pollution. Wherever human light spills into the natural world, some aspect of life for animals—migration, reproduction, hunting and feeding—is affected.

The most well studied incidence of this can be seen in the case of sea turtles. Sea turtle hatchlings instinctively know to head toward the brightest source of light, because for hundreds of years before mankind mastered the darkness, starlight reflecting off the ocean was the brightest thing on the beaches. But with coastal cities flooding the night with their bright lights, the hatchlings become confused and disoriented, heading toward the cities and not the sea, falling prey to dehydration and predation and never reaching safety of the ocean.?

Effects on the Economy

While the environmental effects of light pollution are tragic, the economic effects can be just as shocking. The International Dark-Sky Association estimates that 1/3 of all lighting is wasted at an annual cost of $2.2 BILLION dollars. The light projected directly upwards from a cobra-head streetlight is about 30% of the total light it emits! To put that in perspective, the average desk lamp uses 40 watts of electricity. To generate so much electricity, predominantly coal-fueled power plants expel around 15 million tons of carbon dioxide pollution to the atmosphere each year. So much air pollution results from the creation of electricity that fixing light pollution would be the equivalent of removing 9.5 million cars from the roads.

How Can We Fix Light Pollution?

Addressing light pollution effectively involves turning off unnecessary lights and utilizing fully shielded, efficient fixtures to minimize sky glow, which can reduce artificial sky brightness significantly. Incorporating thoughtful lighting design—considering the appropriate intensity, timing, and color temperature of light—further mitigates pollution, enhances safety, and conserves energy. This strategic approach not only preserves the night sky but also offers substantial energy savings and environmental benefits.