Light Pollution Harms Life on Earth but the Solutions are Simple

Aug 31 2020

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light pollution, stars, dark skies

When was the last time that you looked up at the sky to count the stars? If you live in the Chicago area, you’d be done pretty quick: only about 35 stars are visible on a clear night. The culprit? Light pollution. Besides being a far cry from the awe-inspiring 4,500 stars visible in a truly dark sky, there are a lot of other impacts from light pollution beyond the celestial. It is a growing global issue that affects our health, the health of wildlife, plants and our planet. Fortunately, the solutions are simple. Read on to learn more and find out how you can help save the night.

See what we are missing when light pollution affects our view of the night sky in this inspiring short film.

What is Light Pollution?

Less than a century ago, people across the globe could look up and see a sky full of stars. Now, only 2 out of 10 people can see the Milky Way where they live thanks to the widespread use of artificial light outdoors. Most light is only needed at ground level but much of it extends beyond where it is useful, invading our homes, skies, and wild places where it has many negative effects.

light pollution, space, US, dark skies
Light pollution in the U.S. as seen from space in 2012. Image from NASA Blue Marble Navigator.

Light pollution is so intense it can even be seen from space! Not only that, all that extra light going upward and outwards is a big waste – lighting spaces too brightly, when and where it is not needed.

The Impact of Light Pollution

The natural light-dark cycle of our planet gives cues to all living things in relation to the life-sustaining behaviors of sleep, nourishment, reproduction and protection from predators. Plants even have daily cycles influenced by light. By lighting up the night, we’ve disrupted this cycle. 

Human Impact

For people, darkness  indicates that it is time to rest and recover. Artificial light can trick our bodies, which evolved over centuries on reliable light-dark cycles, and mess with our natural sleep patterns. Not only can it keep you awake, exposure to artificial light late in the day impacts our immune and endocrine systems, and heart health. It has even been linked to an increased risk of cancer, diabetes, and cardiovascular disease. It is such a concern that the American Medical Association released a recommendation on outdoor lighting.

light pollution, sleep
Exposure to artificial light can disrupt natural sleep patterns but the effects extend beyond a bad night’s sleep.
Wildlife Impact

For wildlife, the impacts may be worse, especially for nocturnal creatures. Light glare across wetlands disrupts amphibians nighttime breeding, reducing populations. Bright lights near beaches draw baby sea turtles away from the ocean – killing millions each year. Migrating birds go off-course into cities, confusing artificial light for that of the moon and stars which they use for navigation, where building collisions cause an untimely death for about 1 billion each year. Insects hovering around lights are an easy target for prey, which can lead to a decline in population levels affecting the base of the entire food web. These are just a few examples of the many species affected by light pollution.

wildlife, birds, migration
Migrating birds are lured off-course by artificial light.
Climate Impact

Light pollution also has big consequences for our climate. Light pollution is a huge waste of energy. To offset the greenhouse gas emissions resulting from powering light pollution, we would have to plant 875 million trees each year. It’s a drain on our financial resources too. According to the International Dark Skies Association, we’re spending over $3 billion each year to power ineffective outdoor lighting – and that’s just residential lighting!

energy, greenhouse gas emissions, power plant

How to Protect Night Skies: Use Light Wisely

The good news is that light pollution is simple to remedy and the effects are immediate, unlike most other forms of pollution. It all comes down to better lighting design. It can be summed up here: 

Light where you need it, when you need it, in the amount needed, and no more. 

The International Dark-Skies Association outlines five principles for responsible outdoor lighting

Useful Light Only

All lights should have a clear purpose. Before installing or replacing a light, ask yourself if light is actually needed. Consider how light will impact the area and if reflective paint or self-luminous markers for signs, curbs, and steps will meet your need.

Aim Down

Only light the area that actually needs light. Fixtures should be carefully aimed and shielded so as not to shine upwards or beyond the area that needs lighting. Avoid upward lighting (such as that used for landscape or architectural lighting).

light pollution, dark skies, streelights
This image shows the effects of shielding on light pollution. On the far left, an unshielded light spreads light all over. On the far right, a fully shielded light directs the glow to where it is needed, no further. You can see the effects on the sky above the lights.
Brighter isn’t always better

Use the lowest light level required for your purposes. This both saves money with a lower power fixture and actually makes for better visibility.


Most outdoor lighting doesn’t need to be on all night long. Consider using controls such as timers or motion sensors. Dim light when possible and turn it off when not needed.

Color Matters: Choose LEDs Wisely

LED lights are fantastic when it comes to conserving energy. They operate at up to 90% energy savings compared with incandescent lights and last much longer. However, they can give off a cold, harsh blue-white light. This color of light is much more damaging to our health and the environment and actually makes it harder to see at night due to glare. Fortunately, LED technology has come a long way. Bulbs are available with a much softer, warmer shade of light. Warm shades of light mitigate many of the problems of light pollution, make for a more pleasant experience and actually make it easier to see. Bulbs should be 3000 Kelvin or less (the unit that measures light color). “Soft white” bulbs typically fall in this range but check the Kelvin rating displayed on bulb packaging.

light pollution, LED, streetlights, dark skies
A comparison of blue-white LEDs with Amber LEDs.

You can find a list of dark-sky friendly light fixtures here.

SCARCE worked with Doyle Signs to make our new building signage Dark-sky friendly: the top of the letters are opaque to prevent up-lighting and the light is on a switch so it can be turned off.

Making a Difference in Your Community

Not only can you make the outdoor lighting around your home dark-sky friendly, parks, preserves and even whole communities can address their outdoor lighting to ensure safety, save energy, and preserve the night. 

This is especially important as many cities upgrade their lighting to LED technology. There are a growing number of cities that are making dark-sky friendly lighting a priority while still realizing energy and safety benefits.The City of Tucson, Arizona has a progressive lighting ordinances to help ensure intelligent use of outdoor lighting and a clear night sky for residents and the many observatories in the area. Residents in this metro of just over 1 million people can see the milky way from their own driveways. See how two small towns in Colorado benefited from installing dark-sky friendly lights in this story from The Today Show.

The International Dark-Sky Association has resources to guide individuals, organizations, and municipalities to make responsible lighting retrofits and sample lighting ordinances. Municipalities, parks, and preserves can even be recognized for their efforts through the IDA’s  International Dark Sky Places program. In Illinois, the villages of Homer Glen and Hawthorn Woods and the Middle Fork River Forest Preserve in Champaign County have all received recognition.

Dark-sky friendly lighting practices are simple changes to make that are a win all-around. We can protect our night skies, save natural resources, protect our health and wildlife, save money, and preserve – even enhance – our view of our wondrous night sky. Now that’s a bright idea.

Learn more and find ways to get involved at

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