What is light pollution?
We’ve all heard about different kinds of pollution. Examples include air pollution from carbon monoxide, water pollution from industrial waste, and soil pollution from pesticides. But one overlooked type of pollution relates to artificial light. It’s called light pollution. Light pollution is unnecessary, misdirected, or improper artificial outdoor lighting.
It generates light spillover into unwanted areas like nearby properties.
It produces unnecessary glare that makes it difficult to see at night.
It creates the inability to see the night sky properly and creates skyglow in populated areas.
It wastes energy.
What can we do to reduce light pollution?
Fortunately, there are many ways that we can reduce light pollution. Here are nine strategies to use:
1. Use LED lights
LED light technology has advanced quickly in the last several years. They are the best type of light to help reduce light pollution because they have a more focused light beam than other types of lights such as fluorescent or metal halide. This prevents spillover into unwanted areas. Other benefits of LEDs over other types of lights include:
They have a longer lifespan.
They use less energy.
They possess better light quality.
They have better dimming capabilities.
2. Use shades or covers that force the light downward
Shades or covers help the light to better focus on the intended lighting area. Their usage produces less spillover. They can be part of the original light fixture or can be purchased separately.
Fortunately, LED Lighting, for the most part, is very directional. So aiming the light where its needed is easier to do that traditional light sources, like metal halide or high pressure sodium lighting
3. Minimize your light use in general
One easy way to reduce light pollution is to simply use less of it. Here’s how:
Use fewer lights. Only use what is necessary.
Create a smaller targeted illumination area. Only focus on the lighted area and nothing more.
Reduce the duration of their use. Outdoor lights do not need to be turned on all night long outside of security concerns.
4. Reduce decorative lighting usage
Decorative lighting adds a festive touch to outdoor spaces, especially during holidays or celebrations. But it’s easy to go overboard. It’s best to show a little restraint here. Even when kept to a minimum, try not to have them turned on all day and night.
5. Use lighting controls
These days, there are many ways to automatically limit light usage with lighting controls. Here are a few examples:
Use dimmers to reduce the intensity of the light.
Use motion sensors so that lights only turn on when someone is in the area.
Use timers to control when lights turn on and off.
6. Direct the light away from neighbors and neighboring properties by using shields
Light shields are accessories that you can attach to the top and/or the side of light fixtures. They are also known as light shrouds or glare shields. They focus light downward or inward, so it doesn’t spread in an unwanted direction. Light shields provide many benefits, including glare reduction and improved night vision.
What kind of applications can you use light shields with?
Standard Wall Pack Light Shields
Semi-cutoff or full-cutoff wall packs already have a design that focuses light downward. There is no reason to use a shield.
There is generally not much use for a shield on a wall pack but if you already have a standard wall pack, you can further reduce light pollution by using one. A wall pack light shield is attached to the top of the fixture to focus light downwards.
Shoebox / Parking Lot Light Shields
In the case of shoebox or parking lot light shields, back shields can be installed on the fixture to stop the light from backward distribution. This is important so that the light cannot trespass on another property near where the lights are installed. It keeps the light focused on the parking lot or other area that is to be illuminated.
Stadium / Sport Field Light Shields
In the case of stadium / sport light shields, they can stop both light pollution upward and limit sideways glare for ball players and spectators. This is important so that the lights do not affect the players ability to make a play especially when they have to try and catch a ball that’s hit or kicked in the air. And since most sports field lighting has tight optics, the glare shield should not affect the lights ability to light the targeted area on the playing field
Flood Light Shields
Flood or spot light shields can be installed on the top and/or sides of the fixture. This prevents the light from going upwards or to the side(s). Only the general target area of the light is illuminated.
The top shield also helps with limiting upward light tress pass and helps to ensure the light is only directed where its needed
Should you use light shields with LED lights?
LED lights are more directional than other types of lights such as fluorescent or metal halide. In the case of street lights, parking lot lights, and floods or spots, each type of fixture has a defined beam angle. However, they could still utilize a shield in some instances such as in densely populated areas.
Illustrated Guide to Properly Shielded Light Fixtures
The graphic to the right provides many examples of shielded and unshielded light fixtures. As you can see, when a light source is not shielded, two things are possible:
The light is allowed to spread in all (or most) directions causing spillover into unwanted areas.
The light is not completely focused downward or inward and causes glare issues.
7. Avoid using lights in the blue spectrum
The color of light is measured in Kelvins (K). Their associated values are expressed as correlated color temperature (CCT).
One end of the light spectrum has what’s called a “warm” color appearance. These colors appear as red or yellow and are represented by lower CCT values.
The other end has what’s called a “cool” color appearance. These colors appear as white or blue and are represented by higher CCT values. These usually start around 6000K.
The chart to the right displays CCT values across the spectrum and their equivalents
The best colors in the spectrum to use outdoors are yellow, red, and amber. They don’t affect nighttime vision and produce less glare.
For outdoor lighting, use warmer color temperatures (CCT). The CCT of your outdoor lights should be less than or equal to 5000K. Avoid the blue light spectrum which is associated with LED lights that have a higher CCT above 5000K. Blue light has a larger geographic reach and creates more glare.
8. Use blinds or curtains to conceal indoor light as much as possible
Indoor lighting can also affect the level of light pollution in an area. Its light will still spread outside of a house or building if your windows are not covered. This can be further accomplished by using blackout curtains or blinds.
9. For coastal areas, use wildlife-friendly lighting
Some communities in coastal areas require the use of amber lights in outdoor areas. For example, in some parts of Florida, they are used to protect sea turtles. Sea turtles lay their eggs in areas near the ocean. When they hatch, the baby turtles will instinctively move towards the water and begin their new life at sea. Artificial light from coastal structures causes them to be confused and they head in the wrong direction. This puts them in danger from predators or human activity such as automobiles.
The International Dark-Sky Association (IDA)
The IDA is a non-profit organization that promotes Dark Sky Compliance initiatives. It provides resources to help reduce light pollution which include:
A Dark Sky Lighting Friendly list of products approved by the IDA. Their website can be found here: https://www.darksky.org/
Please see our blog post for more information about Dark Sky Compliance: https://www.ledlightingsupply.com/blog/dark-sky-compliance
About the Author
Neil Peterson is Chief Operating Officer at LED Lighting Supply. He has been active in the LED industry for over 10 years and is responsible for product planning and management as well as revenue and operations at LED Lighting Supply. Much of Neil’s time is focused on customer engagement for large commercial and industrial lighting requirements. When not working, he enjoys family time, camping, fishing, and sports..