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Light Pollution:

    vs. Astronomy

    vs. Culture

    vs. Human

    vs. Nature

    vs. Economics

    vs. Security


International Year of Astronomy link

Image of Bob Crelin's Once Threre Was a Sky Full of Stars

main col hack
"Knowing is not enough; we must apply. Willing is not enough; we must do."


Prevent Light Pollution

The topics discussed on this page cover how to prevent light pollution, in particular the topics are:

If you would like to learn reasons to prevent light pollution, then consider some of its impacts in the pages listed in the blue column menu on the left.

FLASH:A new study reports that lights on at night can worsen smog conditions for a city!

Public Broadcasting Station's P.O.V. will give an encore showing of Ian Cheney's The City Dark - Monday, August 12th, 2013

The City Dark: Addressing Light Pollution

By thinking critically about lighting design and what it can return to us, it becomes possible to reduce light pollution and also conserve energy.

Blending a humorous, searching narrative with poetic footage of the night sky, The City Dark provides a fascinating introduction to the science of the dark and an exploration of our relationship to the stars.

Winner, Best Score/Music Award, 2011 SXSW Film Festival. Produced in association with American Documentary | POV.

Watch The City Dark: Addressing Light Pollution on PBS. See more from POV.

Reducing Light Pollution

Just in the same way that scientists do not need to research how to reduce a neighbor's noise level, reducing light pollution is not ever going to be a problem that scientists will need to research to correct. The problem is one that any ordinary person will add to by the poor usage of their lights. Thus this is a problem that has been ignorantly or apathically created by our habits. So, until there are code enforcement on laws regarding the usage of light, it is really up to us, everyday folks, to understand and to solve it on our own. So what can you do to reduce light pollution, save energy and bring back the beauty of the night sky? Here are a few ideas:

  • Learn the Facts -- Most importantly, educate yourself on the issues. Explore our pages or visit the International Dark Sky Association for a wealth of outdoor lighting information. Joining the IDA is a great way to show your support for reducing light pollution, which makes better use of natural resources and helps perserve the sky for amateur astronomy, for ourselves and our future generations. The IDA provided information that you can use, such as their Practical Guide for Residences. This guide not only includes information about what to install and how to do it, but also a suggested letter you can use to approach a neighbor who has a light that is glaring at your home. Excerts from that guide are reprinted in the Practical Action Tips and Good Neighbor Letter sections below.

  • Talk About It -- Another way to help is to explain to others about the problem of light pollution. One very child friendly book you can get about the issue is There once was a sky full of stars by Bob Crelin and Amie Ziner, published and sold by Sky and Telescope. It is a wonderful read that easily coveys the issue and brings to the forefront what lost wonders our obsessive lighting steals from our children. I especially like and connect to their descriptions of the lost dreamland yards. To get an idea of how many stars are lost due to light pollution visit the Astronomy, Our Perceptions of Light, and the Impact of Light Pollution section on our LP vs. Astronomy web page.

  • Floodlights make glare and shadows, plus unhappy neighborsFix Your Fixtures -- Ensure that you are not part of the problem by checking outdoor light fixtures around your house and/or business. Ensure that the lights do not shine upwards nor outwards and unnecessarily at night. Install the lights high on your home or building. Have the lights pointed downwards and use full cutoff luminaires to better control and direct the light to where it is needed and not to where it is unwanted. The picture at the right shows the good light being placed higher on the house and pointed downwards, this eliminates the shadow regions near a light that can hide a bad guy. Correct those lights that do. Remember, the basic goal for lighting is this:

    no light should be emitted above
    the source's horizontal plane.

  • Reconsider Security Lighting -- Often touted by the security and lighting industries (especially with dramatic commericials), it is a reoccuring myth that lighting increases security, when in fact FBI statistics show that most home crime occurs during the daytime. Thus if light prevented crime, then there should be no crime at all during the bright daytime. But that is not the case. A friend of mine countered this arguement by stating that criminals need to sleep, too. Obviously, so then if criminals sleep during the night as nice, law abiding folks do, then who are all the lights left on for?

    However, if you are determined to use lights for security, then not only will setting them to be controlled by motion-sensitive electronics is a much better way to eliminate unnecessary lighting and reduce electricity costs, but it may also increase your household security effectiveness, because the active lighting may draw attention to movement in an area, rather than just wastefully leaving them on all night long. This of course, assumes that anyone is on guard watching what the lighting shows.

    Also, you should be aware that the motion sensors and the lights are often mounted together with the sensor on the bottom. This means that the sensor will often point the light higher than it should, and so, emit light above its horizontal plane. Please ensure that the lights are adjusted correctly.

    Remember this: criminals need light, too! Security lights announce and advertise that there is something in your house that needs protecting. Criminals will check out your house to see how easy it is to rob. They will check to see how easy it will be to escape from, if they need to. Leaving lights on may just make it that much easier for them to figure this out.

    Finally, after installation, remember to test out your motion sensor's sensitivity levels. A light that goes off at the slightest movement will quickly become ignored when insects, swaying tree branches or other natural movements, too easily trigger your light's motion detector, which would then defeat its purpose. Don't let your light cry wolf!

  • NO Landscape Lighting! -- Using lights to illuminate your trees, houses and land is strongly discouraged. Not only does this pure act of vanity contribute to glare and light trespass, but it could also harm the very plants or trees that are being lit. Many trees adjust their growth based on light levels. Artificially changing the light levels impairs the plant's ability to respond to the changing seasons. (Learn more at our Light pollution vs. Plants page.) However, if you still insist on installing landscape lighting, you should at least focus the fixtures downward so that its angle does not exceed 45 degrees from the ground to reduce glare and light trespass and use lamps of the lowest wattage lamps possible. Also, landscape lighting should be controlled by a timer, so that the lights turn off by 10 p.m. While I am all for solar energy usage as they do not use household electricity and are often (for now) low to the ground, the use of solar landscape lighting should be avoided when possible, for they can not be turned off, so they stay on all night or until their batteries run down. As such, they are yet another unneccessary light source.

  • Two cobra-head style streetlights.Street Lighting -- If you live on a street with poorly designed cobrahead or NEMA-style light fixtures, call the local power company, (for us here it is Florida Power and Light or FPL) to complain about the glare and request that the fixtures be changed to full cutoff, or better yet fully focused designs that reduce glare and improve visibility. Note that the older cobrahead lights have drop down lenses that scatter light outwards and into people's eyes. Newer cobrahead light have eliminated the drop lens in its design. You may notice that these newer designs are increasingly part of the newer lights on Interstate 95. But local street lighting, where people live and sleep, is sorely behind the changes. The local power company here, FPL's number for Residential Services for Palm Beach County is (561) 994-8227 and for Broward County is (954) 797-5000, or you can use the FPL contact page. Public demand for better, more efficient fixtures is a good way to ensure that the positive trend continues.

  • Neighbor's Lighting -- An ironic situation occurs here in that if you had late night, noisy neighbors or if they had a dog that barked all night long, authorities will respond to handle this matter. However, if you reported that a neighbor's light is equally bothersome and that it interupts your sleep, they'd just shrug their shoulders. So, until this changes, if you have neighbors with unnecessarily bright, poorly designed lights, try talking to them tactfully and politely, and understand the issues they are trying to solve. Offer them alternatives like motion-sensitive lights that beautify their property, draw attention to movement and save money. If you have a telescope, one introductory method you can try is to offer your neighbor a look at some bright deep sky objects or planets, and then point out that even more can be seen if the lights were shut off or replaced with full cutoff designs that keep the glare out of your eyes. Some tips from the International Dark Sky Assoc. are listed below that describe what to do about a neighbor's annoying light. Another introductory method to try is to use the Good Neighbor Letter below. The recommended tactic is to be politefully persistent.

  • Commerical Lighting -- If you are a customer at a restaurant, convenience store, car dealership, shopping mall, home improvement center, grocery store or other establishment that has poor, glare-producing parking lot lights, do not be afraid to politely speak to the manager and let him or her know about energy-saving alternatives that improve visibility and safety.

  • Lights From Outside -- Finally, do what you can to insure that the conditions in which you regularly sleep in are as dark as possible. One measures of night light levels one group of scientists sorted their data by was whether or not the subjects could see their own hands in the darkened state. If they could, then that light level was already enough to shift them away from the ideal sleeping condition. More details on how to do this are listed in the next section.

Protecting Yourself from the Effects of Light Pollution in Your Home

You can make small simple adjustments to your envirnoment, which may go a long way to benefitting you. As described in the Light Pollution and Human Health page, there are a few steps you can take to eliminate some of the problems that light pollution causes us. Here is a quick list of things to do:

  • Most importantly, make sure your bedroom is dark! How dark? Dark enough so that you can not see your hand in front of your face when you go to sleep. Get light blocking curtains for your windows and turn off the lights.

  • Do not leave a nightlight on as you or your family sleeps. Do not leave the television on when you or your family sleeps. Not only will these affect your sleep, but they will certainly affect your electric bill.

  • If you really need to use a nightlight, turn it on only when you are actively using it. When done, turn it off. And choose a bulb or light source that is as RED as possible.

  • If you use an alarm clock, use one with a RED light source on it, such as one that uses red LED digits.

  • Shift workers: If you have a second or third shift job that requires you to sleep during the daytime, it is even more important for you to ensure that your bedroom is dark. Your very own job is considered to be a risk factor for cancer. Ensuring your sleep time is as dark as possible, is the only way you can ameliorate the effect.

  • If you leave lights on outside your house, please turn your outdoor lights off too. For it is quite selfish to protect you and your family from the long term damaging effects of light pollution, and yet not to give your neighbors the same consideration. This is a classic Do unto others as you would have others do unto you type of behavior that so many people profess to follow, and yet few really do. Just because your neighbors may have not heard of the problems of light pollution, does not mean that they are not affected by it, too.

Practical Actions - Tips for how to better deal with Light Pollution from others

Practical Guide for Residences.

International Dark-Sky Association

IDA International Headquarters, Tucson, Arizona

Many of us have experienced this scenario: Your neighbors have installed a new light on their property. It is an unshielded fixture that casts a bright light with no control and lots of glare. The light trespass from this fixture produces light pollution and energy waste. Their new fixture is lighting up your yard or shining into your home, maybe even illuminating your bedroom and disrupting your sleep. Your neighbors cite safety as the reason for installing this light. The illumination gives them a newfound feeling of security.

What your neighbor may not know is that unshielded fixtures that create glare and splatter light everywhere may make a property less safe by not focusing the light where it is needed. Likewise, your neighbor also may not be aware of how you are affected by the light trespass coming off the property.

How do you talk to your neighbor about this situation? The International Dark-Sky Association has provided the following steps to educate your neighbor, and by extension your community, about the value of dark sky friendly lighting.

  1. Make friends, not enemies. Your neighbors probably don't realize the light is bothersome.
    • Always approach people in a friendly, non-threatening way. See the introductory letter below.
    • Don't argue. Be tactful and understanding about their right to light their property.
    • Don't dismiss their need to feel safe.
    • Suggest alternatives to their current fixture. Ask them to move the light, shield it or add a motion sensor.

  2. Be informative. Talking to your neighbor is an exciting chance to be an advocate for good lighting and share knowledge on an important issue.
    • There are many reasons to use dark sky friendly lighting. IDA sound bites can help to convey the benefits:
      • Dark sky friendly lighting does not mean dark ground.
      • Safety is important, but brighter does not mean safer.
      • A starry sky is a natural resource that anyone has a birthright to enjoy.
    • The topics of safety, energy savings, cost, wildlife and human health factors are addressed briefly in their documents and in our associated pages here. Additional articles and brochures from the IDA Web site are downloadable and free for use. Print off free materials from the IDA Education tab and present this information to your neighbor.

  3. Do your homework and be prepared to address the real issues.
    • It is useful to know the local costs of electricity (cents per KWH), and the local lighting control ordinances. This information is available on most city Web sites, from your regional utility company, and on your utility bill.
    • You may also want to compile a list of local businesses with good quality lighting as an example of effective security measures that are dark sky friendly.
    • A list of shielded light fixtures to provide as alternatives to your neighbor's current light is also recommended. A comprehensive list of dark sky friendly fixtures and devices is available on the IDA Web site in the Fixture Seal of Approval section.
    • If there are any further questions, call them at: 1 520 293 3198, or e-mail them at IDA will answer!

  4. Stay positive. Don't let bad lighting create a feud in your residential area.
    • Remember that home is a place where everyone wants to feel relaxed and safe.
    • Accept your neighbors' need to feel secure and politely ask them to accept your need to enjoy the nighttime environment in your own yard.
    • Explain that light trespass is a form of light pollution, but never threaten to sue. The idea of a lawsuit can create bad feelings among the whole neighborhood.
    • Remember that everyone wants the same thing: a chance to relax in their own environment. Work together to create an atmosphere that benefits the community.

IDA's Good Neighbor Introductory Letter

Putting your thoughts in writing is good way to avoid a miscommunication. IDA has offered this sample letter of issues you may want to convey to a neighbor if a lighting nuisance ever arises. Don't forget to edit it as what would be appropriate for your situation.

Dear (insert name),

Allow me to introduce myself, I am your neighbor (insert name) and I would love to talk to you about good outdoor lighting. I have noticed that you have installed outdoor lights on your property, and I applaud your desire to help improve our neighborhood.

At this time your lights are a bit too bright and they are shining in (pick areas as they apply: our bedroom window, the backyard, into our house etc.), and interfering with our (sleep, hobbies, view of the sky, etc). I'm sure you weren't aware of this and I wanted to bring it to your attention as soon as possible to avoid any misunderstanding. Let me be clear, I am not asking you to remove the lights, but perhaps they can be re-directed onto the ground where they will do the most good.

In addition, we could work together to shield the lights so that they are even more effective. Shielding a lamp usually requires a lesser wattage bulb, which is a big money saver within just a year's time. Shielding reduces glare which can be blinding and produces fewer harsh shadows where the "bad guys" can hide. Dark sky friendly lighting provides real security, not just an illusion.

There are other ways to save money and still be safe. When lights have motion sensors, they provide an alert if someone is in your yard after dark and they save you money by keeping the lights off when they aren't needed. Timers are another money saver because they can turn off your lights when you will not be using the yard; for instance, when you retire for the night.

Thank you so much for your time and understanding. I would love to talk with you about the advantages to using dark sky friendly lighting and how it benefits your safety, your budget, and the night sky.

Your Neighbor (your name and contact information)

Some notes about legal actions that have been tried.

What follows are some pieces of information that are provided to help people become aware of what has been tried in a legal court, what the difficulties were and what were the results. What is sad is that many laws recognize the invasiveness of foul oders or incessantly loud noises at disturbing the peace of a recipents that do not wanted such assaults on their senses. Yet many have yet seemed realize a similar insult occurs to peoples' eyes. Note, that I am not advocating that people try these steps as they seem to be very time and fiscally draining. Friendlier and more personaly direct methods, such as the above letter, may meet with more immediate success. However, the recognition of the widespread problem will have to be accepted, and fortunately some precedent have already been achieved and with some advanced strategic work, this information may be very useful for those that need it.

The first case, which is rather old, I have very little information to go on and I am not a legal representative of the court, so down here in south Florida, I do not have original sources to the information. What is here is second or third hand information, so it may not be entirely accurate. Hopefully it is and that someone may find it useful.

Lawsuit: Pennsylvania
Hetzer et al vs. Paparo et al
Paparo et al vs. Hetzer et al

Source: Montgomery County Law Reporter, February 1, 1968, page 142.

Judge Honeyman

The property in question is located on Church Rd., Lafayette Hill. The test for nuisance applied in Hetzer v. Paparo was that if the intensity of the light shining from the adjoining land is strong enough to disturb a person of ordinary sensibilities, it is a nuisance and must be corrected.

The court did not recognize any right to protection for persons who were hypersensitive to outdoor lighting.

The next case occured in Golden, CO and is defined as being "not unpublished". As such, they have some rules about not publishing the case. What follows is what can be learned from other the linked sources. The case is described by the plaintiff on his website: There is also a link to a .pdf file that includes the very brief announcing results to the case. Again, I am not a legal representative, so I can not verify the accuracy to the case as described by the plaintiff, Mr. Cash. It is only here so that someone may find it useful, or at least instructive.

Lawsuit: Colorado
Cash vs. Emich d.b.a. Elway Chrysler Jeep West & Elway Subaru West
Golden, Colorado, 2006.

Source: Colorado Court of Appeals in Denver.

The oral arguments took place in August 2006 and the appealed ruling was announced in September 7, 2006.

Mr Cash states that the court held that the lights were an actionable nuisance. The jury found that the defendants (the car dealerships) were creating, maintaining and/or allowing a nuisance to exist. Paraphrasing, the court held that the laws are sensitive to property owners rights to use and enjoy their private property, without having to close blinds or curtains on their windows to accommodate a business interest (the bright lights). The lawsuit has set a new precedent for nuisance light, which gives relief from bright lights that interfere with the use and enjoyment of one's private property.

Mr. Cash states that the lawsuit is considered to be a persuasive precedent, which means that its decision is not mandatory followed, however, it maybe relavent or useful to others. Attorneys can find it using Westlaw Legal research at: 2006 WL2567678. A regular citizen can use the Colorado Courts website under the Court of Appeals Opinions - Case Announcements page. Click on the year 2006 to obtain the records then, and then the date the case was announced, which was Sept. 7, 2006. If you want to request a copy of the case's opinion, you'll need to follow the instructions to request a copy of the final decision by the Court of Appeals. The case number "04CA2444" may be required, and the case is listed as Cash vs. Emich d.b.a. Elway Chrysler Jeep West & Elway Subaru West.

Following the above instuctions, I found reference to his case on page 16 at There, the file has under Published Opinions:
Court of Appeals No.: 04CA2444
Jefferson County District Court No. 03CV3643
Honorable Leland P. Anderson, Judge
David N. Cash,
Emich Oldsmobile LLC, a Delaware limited liability company, d/b/a John Elway
Chrysler Plymouth Jeep West and Emich Subaru West LLC, a Delaware limited liability
company, d/b/a John Elway Subaru West,


Division V
Dailey and Webb, JJ., concur

Mr. Cash covers quite a bit of information about the case on his website. He also states that his legal expenses were very high and that, while he won, sort of, the city did not force the dealership to alter the lights. Mr. Cash informs me that the district court judge in Jefferson Co. did order the Subaru car dealership to shield their lights with four-sided shields. That order was given on July 20 '04. So they have been shielded properly. Again, legal proceedings may not be the best way to go. As to Mr. Cash, I still wish you the best of luck.

Links to other sites about light pollution

Links to vendors that offer items that would help combat light pollution

Why should folks in rural places be the only ones who get to not only have a healthy nights rest but also be able to enjoy the night's sky. With that in mind, here is a list of vendors that offer lighting solutions to light polluted city skies.

  • First, the International Dark-Sky Association maintains a list of lighting and other vendors that take responsibility for preserving our night skies. There is plenty of products to choose from there!

  • Starry Night Lights offers lighting solutions to promote the night sky! Please, check them out for your outdoor lighting needs.

  • The Original GlareBuster is the environmentally responsible outdoor light!

  • Green Earth Lighting specializes in environmentally friendly outdoor lighting. Their lighting products help you keep glare to a minimum, produce no direct uplight, use the minimum amount of light needed for the task and put light only where it is needed when it is needed, while improving visibility, providing a safe enviroment and reducing energy costs.

  • Or consider's Utility Series products for outdoor street lighting. They offer responsible lighting solutions that meets the IESNA definition for full cutoff or fully focused light distribution that reduced urban sky glow.

  • The FlagPoleWarehouse has a money saving solution to prevent light pollution from illuminating flag poles. Cleverly arranged, down pointing and cost effective lights are placed at the top of the pole and attached to the top rope pulley for the flag. Where the flag blows, its light is sure to follow. Since the light source is close to the flag itself, energy and money is not wasted by illuminating the flag from far below. You really can be patriotic, environmental and cost effective too!

Department of Physics
Florida Atlantic University
Boca Raton, Florida
E-mail: evandern at fau dot edu
Phone: 561 297 STAR (7827)

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