When we hear the word “pollution,” we tend to think about factories spouting gasses and chemicals into the air, car exhaust, and run-off entering our water. While we tend to focus on this type of pollution, light pollution is also a hazard not only to our environment but also to our health. If we take the time to consider and implement ways to minimize light pollution in our daily lives, we can better the environment and our health at the same time. We can each minimize our daily contribution to light pollution starting with our own homes and places of business.
Types of Light Pollution
There are many types of light pollution that radiate from various sources. The heavier an area is populated, the worse the light pollution becomes. Light pollution is the use of excessive artificial light to illuminate areas that do not necessarily need lighting. According to the Lighting Research Center, there are three types of light pollution: glare, skyglow, and light trespass. Each of these types can contribute to one another.
- Glare is excessive brightness that can distort vision and cause eye discomfort. This type of light pollution commonly comes from our use of televisions, personal computers, laptops, smartphones, and tablets. There are also sub-categories of glare, such as disability glare and discomfort glare. Both types cause various loss of night vision from bright and poorly designed lights.
- Skyglow occurs over urban and suburban areas where artificial light is needed in the evening. This can come from building and antenna illumination and spotlights. The evening skyline of Los Angeles has skyglow light pollution, which gives the air around the city an orange glow.
- Light trespass is light falling where it is not For example, street lights and lights illuminating an entryway. The light tends to spread beyond its intended spot, causing night blindness and decreasing visibility of the night sky.
For more information, visit:
- CIRES: Light pollution map
- Dark Skies Awareness: What is light pollution?
- Prairie Astronomy Club: Light pollution fact sheet
Safety Concerns Related to Light Pollution
Excessive light pollution can cause numerous health and environment issues. The main safety issue is the health and ability of our sense of sight. As reported by the Florida Atlantic University, the use of excessive light at night causes the night vision we do have to decrease incredibly. The rod cells in our eyes give us the ability to see in the dark. However, light pollution cancels the cells ability to do so. The glaring light decreases our ability to see in the dark beyond the light, thus causing one to temporarily become night-blinded. This is a huge safety concern when walking around at night, whether it is seeing a possibly dangerous person in the shadows or an obstacle in our path that can cause us harm. To learn more, visit:
- Dark Society: Lighting for safety and security
- National Institute of Justice: Crime solutions – Improved street lighting
- Illinois Coalition for Responsible Outdoor Lighting: Why does outdoor lighting matter?
Driving and Transportation
Light pollution not only affects us around the home but can also be a hazard while driving. Highways use bright street lights to illuminate the road with the intention of increasing visibility. However, those street lights can just as easily reduce our night vision. Poorly designed streetlights can cause light trespass, where the light illuminates an area not intended to be illuminated. With decreases in our night vision while driving, we are at a higher risk of being unable to see pedestrians and other obstacles in the road.
Some states have worked to decrease light pollution caused by streetlights. A light pollution handbook from the Maryland Government website states how the eye's inability to quickly adapt to the sudden changes of bright light to no light is dangerous for drivers. Poorly designed streetlights with high powered bulbs cause glare and light trespass, which decreases visibility on the road in front of drivers.
Brightly lit and poorly designed advertisements and highway signs can also distract us while driving, which increases our risk of having an accident. Numerous billboards litter the side of highways. Signs with upward facing lights contribute to skyglow, light trespass, and distracting light. For more information, go to:
- SPIE: LED light pollution
- Volt.org: Davis, California streetlight retrofit
- Flagstaff Arizona Dark Skies: Lamp spectrum and light pollution
Ultra-bright lights that cause light trespass and glare can actually be more detrimental to the safety of your home and business than helpful. Brightly lit areas give us a sense of safety but can actually decrease our eyes' natural ability to see in the dark. Bright lights without shields can cause deep, dark shadows that we could otherwise see objects or people in if they were properly designed.
Constant, bright light from outdoor fixtures actually allow home intruders to assess homes easier. Studies have shown that brighter light does not always correlate to safer conditions at night. A report conducted in Chicago and posted by the Center for Problem-Oriented Policing suggests that crime increased with more light. While more lights decrease our fear of crime, whether it actually decreases crime remains to be seen. For more information, visit:
- Globe at Night: The light pollution safety brochure
- PBS.org: The city dark – Light and crime
- NPR.org: Should you leave your lights on at night?
Health and Well-being
Light pollution not only disrupts our view of the nighttime sky but also disturbs our health. All types of light pollution can be found in our own homes. The biggest culprits are generally our entertainment electronics such as televisions, computers, and smartphones. The blue light radiated from most of these strain our eyesight and cause us to lose the ability to see in the dark. Using devices such as smartphones before bed can cause issues like insomnia, which is a growing problem in the United States.
The type of bulbs we use in our lighting fixtures increases our health issues as well. According to an article by Environmental Health Prospectives, studies concluded that exposure to artificial nighttime lights can disrupt our circadian clock which controls a number of functions like brain wave patterns, hormone production, and cell regeneration. Continual exposure is said to be associated with a few medical disorders such as depression and cardiovascular disease.
In a report conducted by the AMA, it states that the popular LED lights, touted for their energy saving properties, are said to be more harmful to your health than saving a few dollars in energy. The blue light it emits can cause nighttime glare, decreases visual safety, and suppresses the production of melatonin. To learn more, visit:
- Inside Science: Astronomers encourage cities to shield outdoor lighting
- US Library of Medicine: Effect of light on human circadian physiology
- AAAS : Artificial light impacts astronomy as well as human health
Tips and Solutions to Help Reduce Light Pollution
Making a huge impact on reducing light pollution is easy. The suggestions below are things you can easily start right away.
- Use reflectors along your driveway instead of lights.
- Change the type of light bulbs you use. Use warm white or orange-hued bulbs.
- Select lighting products certified by the IDA.
- Turn lights off in rooms you are not
Home Safety Lighting Tips
- Replace bright globe lights with motion sensor lights. Control the sensitivity of the motion sensors, so the lights do not go off with every movement nearby (ex. trees swaying in the wind).
- Use lower wattage bulbs or shields on fixtures. Ultra-bright bulbs can create deep shadows and hinder your eyes' ability to see at night. Lower wattage bulbs or using shields provide light but allow you to see your surrounding area easily.
- Turn off lights outside and inside the home or use low light bulbs.
For more ideas, go to:
- Everything Connects: How to reduce light pollution
- National Conference of State Legislators: States shut out light pollution
- Ventura County Astronomical Society: Light pollution reduction information
- Stow, Massachusetts: Good neighbor lighting pamphlet
Professional Groups and Organizations
For more information or to learn more about light pollution and its effects, please visit the websites below.
International Dark Sky Association has a great amount of information. Start on their main page.
Astronomers without Borders discusses light pollution in relation to star gazing. Visit their main page to get started.
The Astro Society has an informative section dedicated to light pollution.
NASA’s Night Sky Network has a great section on light pollution and you.