There are 4 types of light pollution: glare, over-illumination, light trespass, and skyglow. Light pollution wastes energy, affects human and animal health, and changes ecosystems. It can harm sea turtles and insects that use moonlight to navigate. Solutions are simple - use shielded lights that direct light downward and only where needed, and turn lights off when not in use.

1. Light Pollution
Kinds, Consequences, & Solutions
May 2014

2. There are 4 Kinds of Light
Pollution
• Glare
• Over-illumination
• Light Trespass
• Skyglow

3. Glare
A bright light in your field of view can make it impossible for
your eye to adapt to see in your otherwise dark surroundings

4. Over-illumination
The excessive use of light

5. Light Trespass
Unwanted light originating from beyond your property.

6. Skyglow
Light that made it up to the atmosphere to be scattered back
down to earth. A sky affected by skyglow never really gets dark.

7. Light Pollution has
Consequences
• Wastes Energy
• Affects human and animal health
• Changes Ecosystems

8. Wastes Energy
Light that is not directed down toward the ground where it
can be used is completely wasted—no one uses it.

9. Harmful to Life
• Artificial light at night was
introduced to life on Earth
relatively recently. Life had
adapted to bright days and dark
nights.
• After hatching sea turtles use
moonlight to find their way to the
ocean. Additional lights hinder
their ability to get to the ocean.
• Many insects are thought to use
moonlight to navigate. Additional
lights make it impossible for
them to function at night.

10. Changes Ecosystems
Bats are known to avoid foraging in heavily light polluted areas. An ecosystem
can change drastically when bats abruptly stop foraging and dispersing seeds.

11. Solutions to Light Pollution
Problems are Surprisingly Simple
• Shield lights
• Only use light where and when needed

12. Shielded lights
A properly shielded light allows no light to go upwards where
it can’t be used, yet still amply lights the area around it.

13. Use light only where and when needed
Turn off lights when they’re not in use. Don’t use more light
than you need in an area.

14. Enjoy the stars
Help stop the loss of the night sky by doing your part to fight
light pollution.