Editing Light pollution (section)

==Reduction==

<!-- [[Light pollution reduction]] redirects here. -->Reducing light pollution implies many things, such as reducing sky glow, reducing glare, reducing light trespass, and reducing clutter. The method for best reducing light pollution, therefore, depends on exactly what the problem is in any given instance. Possible solutions include:
* Utilizing light sources of minimum intensity necessary to accomplish the light's purpose.
* Turning lights off using a timer or occupancy sensor or manually when not needed. For example, wind turbines have blinking lights that warn aircraft, to prevent collisions.<ref name="Lewis-2023"/> Residents living near windfarms, especially those in rural areas, have complained that the blinking lights are a bothersome form of light pollution.<ref name="Lewis-2023"/> A light mitigation approach involves Aircraft Detection Lighting Systems (ADLSs) by which the lights are turned on, only when the ADLS's [[radar]] detects aircraft within thresholds of altitude and distance.<ref name="Lewis-2023">{{cite news |last1=Lewis |first1=Michelle |title=A new wind farm in Kansas trailblazes with light-mitigating technology |url=https://electrek.co/2023/09/29/a-new-wind-farm-in-kansas-trailblazes-with-light-mitigating-technology/ |publisher=Electrek |date=29 September 2023 |archive-url=https://web.archive.org/web/20230929161033/https://electrek.co/2023/09/29/a-new-wind-farm-in-kansas-trailblazes-with-light-mitigating-technology/ |archive-date=29 September 2023 |url-status=live }}</ref>
* Improving lighting fixtures, so they direct their light more accurately towards where it is needed, and with fewer side effects.
* Adjusting the ''type'' of lights used, so the light waves emitted are those that are less likely to cause severe light pollution problems. Mercury, metal halide and above all first generation of blue-light LED road luminaires are much more polluting than sodium lamps: Earth's atmosphere scatters and transmits blue light better than yellow or red light. It is a common experience observing "glare" and "fog" around and below LED road luminaires as soon as air humidity increases, while orange sodium lamp luminaires are less prone to showing this phenomenon.
* Evaluating existing lighting plans, and re-designing some or all the plans depending on whether existing light is actually needed.

===Improving lighting fixtures===

The use of ''full cutoff'' lighting fixtures, as much as possible, is advocated by most campaigners for the reduction of light pollution. It is also commonly recommended that lights be spaced appropriately for maximum efficiency, and that number of luminaires being used as well as the wattage of each luminaire match the needs of the particular application (based on local lighting design standards).

Full cutoff fixtures first became available in 1959 with the introduction of [[General Electric]]'s M100 fixture.<ref name="AM-Feb2009-57">{{cite journal|last=Bakich|first=M.E.|date=February 2009|title=Can we win the war against light pollution|journal=[[Astronomy Magazine]]|page=57|issn=0091-6358}}</ref>

A full cutoff fixture, when correctly installed, reduces the chance for light to escape above the plane of the horizontal. Light released above the horizontal may sometimes be lighting an intended target, but often serves no purpose. When it enters into the atmosphere, light contributes to sky glow. Some governments and organizations are now considering, or have already implemented, full cutoff fixtures in street lamps and stadium lighting.

The use of full cutoff fixtures helps to reduce sky glow by preventing light from escaping above the horizontal. Full cutoff typically reduces the visibility of the lamp and reflector within a luminaire, so the effects of glare are also reduced. Campaigners also commonly argue that full cutoff fixtures are more efficient than other fixtures, since light that would otherwise have escaped into the atmosphere may instead be directed towards the ground. However, full cutoff fixtures may also trap more light in the fixture than other types of luminaires, corresponding to lower luminaire efficiency, suggesting a re-design of some luminaires may be necessary.

The use of full cutoff fixtures can allow for lower wattage lamps to be used in the fixtures, producing the same or sometimes a better effect, due to being more carefully controlled. In every lighting system, some sky glow also results from light reflected from the ground. This reflection can be reduced, however, by being careful to use only the lowest wattage necessary for the lamp, and setting spacing between lights appropriately.<ref>[http://www.rpi.edu/dept/lrc/nystreet/ NYSERDA How-to Guide to Effective Energy-Efficient Street Lighting for Planners and Engineers.] {{Webarchive|url=https://web.archive.org/web/20110102010555/http://www.rpi.edu/dept/lrc/nystreet/ |date=2011-01-02 }} NYSERDA-Planners (October 2002). New York State Energy Research and Development Authority.</ref> Assuring luminaire setback is greater than 90° from highly reflective surfaces also diminishes reflectance.

A common criticism of full cutoff lighting fixtures is that they are sometimes not as aesthetically pleasing to look at. This is most likely because historically there has not been a large market specifically for full cutoff fixtures, and because people typically like to see the source of illumination. Due to the specificity with their direction of light, full cutoff fixtures sometimes also require expertise to install for maximum effect.

The effectiveness of using full cutoff roadway lights to combat light pollution has also been called into question. According to design investigations, luminaires with full cutoff distributions (as opposed to ''cutoff'' or ''semi cutoff'', compared here)<ref>{{cite web |url=http://www.eskimo.com/~jrterry/optics.html |title=Optics for Streetlights |publisher=Eskimo.com |access-date=2010-09-04 |archive-url=https://web.archive.org/web/20100915083231/http://www.eskimo.com/~jrterry/optics.html |archive-date=2010-09-15 }}</ref> have to be closer together to meet the same light level, uniformity and glare requirements specified by the [[Illuminating Engineering Society of North America|IESNA]]. These simulations optimized the height and spacing of the lights while constraining the overall design to meet the IESNA requirements, and then compared total uplight and energy consumption of different luminaire designs and powers. Cutoff designs performed better than full cutoff designs, and semi-cutoff performed better than either cutoff or full cutoff. This indicates that, in roadway installations, over-illumination or poor uniformity produced by full cutoff fixtures may be more detrimental than direct uplight created by fewer cutoff or semi-cutoff fixtures. Therefore, the overall performance of existing systems could be improved more by reducing the number of luminaires than by switching to full cutoff designs.

However, using the definition of "light pollution" from some Italian regional bills (i.e., "every irradiance of artificial light outside competence areas and particularly upward the sky") only full cutoff design prevents light pollution. The Italian [[Lombardy]] region, where only full cutoff design is allowed (Lombardy act no. 17/2000, promoted by [[CieloBuio|Cielobuio-coordination for the protection of the night sky]]), in 2007 had the lowest per capita energy consumption for public lighting in Italy. The same legislation also imposes a minimum distance between street lamps of about four times their height, so full cut-off street lamps are the best solution to reduce both light pollution and electrical power usage.<gallery mode="packed">
File:LED Droplight.JPG|alt=This kind of LED droplight could reduce unnecessary light pollution in building interiors.|This kind of LED droplight could reduce unnecessary light pollution in building interiors.
File:Flat-lens cobra luminaire.jpg|alt=A flat-lens cobra luminaire, which is a full-cutoff fixture, is very effective in reducing light pollution. It ensures that light is directed only below the horizontal, which means less light is wasted by directing it outwards and upwards.|A ''flat-lens cobra luminaire'', which is a full-cutoff fixture, is very effective in reducing light pollution. It ensures that light is directed only below the horizontal, which means less light is wasted by directing it outwards and upwards.
File:Drop-lens cobra luminaire.jpg|alt=This drop-lens cobra luminaire allows light to escape sideways and upwards, where it may cause problems.|This ''drop-lens cobra luminaire'' allows light to escape sideways and upwards, where it may cause problems.

File:110101 LightPollution Italian Regional bills specs.jpg|alt=The majority of Italian regions require "zero upward light", which usually implies the use of overall full cut-off lamps for new luminaires, but violations are common.|The majority of Italian regions require "zero upward light", which usually implies the use of overall full cut-off lamps for new luminaires, but violations are common.
</gallery>

===Adjusting types of light sources===

Several different types of light sources exist, each having a variety of properties that determine their appropriateness for different tasks. Particularly notable characteristics are efficiency and spectral power distribution. It is often the case that inappropriate light sources have been selected for a task, either due to ignorance or because more appropriate lighting technology was unavailable at the time of installation. Therefore, poorly chosen light sources often contribute unnecessarily to light pollution and energy waste. By updating light sources appropriately, it is often possible to reduce energy use and pollutive effects while simultaneously improving efficiency and visibility.

Some types of light sources are listed in order of energy efficiency in the table below (figures are approximate maintained values), and include their visual skyglow impact, relative to LPS lighting.<ref>{{cite journal|last1=Luginbuhl|first1=C.|title=The impact of light source spectral power distribution on sky glow|journal=Journal of Quantitative Spectroscopy and Radiative Transfer|date=2014|volume=139|pages=21–26|doi=10.1016/j.jqsrt.2013.12.004|bibcode = 2014JQSRT.139...21L |doi-access=free}}</ref><ref>{{cite journal|last1=Aubé|first1=M.|last2=Roby|first2=J.|last3=Kocifaj|first3=M.|title=Evaluating Potential Spectral Impacts of Various Artificial Lights on Melatonin Suppression, Photosynthesis, and Star Visibility|journal=PLOS ONE|date=2013|doi=10.1371/journal.pone.0067798|pmid=23861808|pmc=3702543|volume=8|issue=7|pages=e67798|bibcode = 2013PLoSO...867798A |author1-link=:fr:Martin Aubé|doi-access=free}}</ref>

{| class="wikitable" style="width:60%;"
|-
!Type of light source
!Color
!Luminous efficiency<br />(in [[lumen (unit)|lumens]] per [[watt]])
!Sky glow impact<br />(relative to LPS)
|-
|[[LED street light]] (white)
| style="background:#fcfcff;"| warm-white to cool-white
|120
|4–8
|-
|[[Sodium vapor lamp#Low-pressure sodium|Low Pressure Sodium]] (LPS/SOX)
| style="background:#fff04f;"|yellow/amber
|110
|1.0
|-
|[[Sodium vapor lamp#High-pressure sodium|High Pressure Sodium]] (HPS/SON)
| style="background:#ffdc9f;"|pink/amber-white
|90
|2.4
|-
|[[Metal halide lamp|Metal Halide]]
| style="background:#fcfcff;"| warm-white to cool-white
|70
|4–8
|-
|[[Incandescent light bulb|Incandescent]]
| style="background:#ffffdf;"| yellow/white
|8–25
|1.1
|-
|PCA-LED
| style="background:#ffdc9f;"|amber
|
|2.4
|}

Many astronomers request that nearby communities use low-pressure sodium lights or amber [[Aluminium gallium indium phosphide]] LED as much as possible because the principal wavelength emitted is comparably easy to work around or in rare cases filter out.<ref>
{{cite conference
| title = Why Astronomy Needs Low-Pressure Sodium Lighting
| conference = IAU Symposium No. 196—Preserving the Astronomical Sky
| author = Luginbuhl, C.B.
| editor = Cohen, R. J.
| editor2 =Sullivan, W. T.
| issue = 196
| pages = 81–86
| publisher = PASP, San Francisco, USA
| date = 2001}}</ref> The low cost of operating sodium lights is another feature. In 1980, for example, [[San Jose, California]], replaced all street lamps with [[low pressure sodium lamp]]s, whose light is easier for nearby [[Lick Observatory]] to filter out. Similar programs are now in place in [[Arizona]] and [[Hawaii]]. Such yellow light sources also have significantly less visual [[skyglow]] impact,<ref name=fdsc-lslp>{{cite web|last1=Flagstaff Dark Skies Coalition|title=Lamp Spectrum and Light Pollution|url=http://www.flagstaffdarkskies.org/for-wonks/lamp-spectrum-light-pollution/|website=Lamp Spectrum and Light Pollution|access-date=10 April 2016|archive-date=23 September 2018|archive-url=https://web.archive.org/web/20180923164443/http://www.flagstaffdarkskies.org/for-wonks/lamp-spectrum-light-pollution/|url-status=live}}</ref> so reduce visual sky brightness and improve star visibility for everyone.

Disadvantages of low-pressure sodium lighting are that fixtures must usually be larger than competing fixtures, and that color cannot be distinguished, due to its emitting principally a single wavelength of light (see [[security lighting]]). Due to the substantial size of the lamp, particularly in higher wattages such as 135 W and 180 W, control of light emissions from low-pressure sodium luminaires is more difficult. For applications requiring more precise direction of light (such as narrow roadways) the native lamp efficacy advantage of this lamp type is decreased and may be entirely lost compared to [[sodium vapor lamp|high pressure sodium lamps]]. Allegations that this also leads to higher amounts of light pollution from luminaires running these lamps arise principally because of older luminaires with poor shielding, still widely in use in the UK and in some other locations. Modern low-pressure sodium fixtures with better optics and full shielding, and the decreased [[skyglow]] impacts of yellow light preserve the luminous efficacy advantage of low-pressure sodium and result in most cases is less energy consumption and less visible light pollution. Unfortunately, due to continued lack of accurate information,<ref>Section ''4.10 What Types of Lamps Are Used in Outdoor Lighting?'' in [http://www.nofs.navy.mil/about_NOFS/darksky/OLCHB1.14/lc-hb-v1-14.html ''Outdoor Lighting Code Handbook''] {{Webarchive|url=https://web.archive.org/web/20161212231714/http://www.nofs.navy.mil/about_NOFS/darksky/OLCHB1.14/lc-hb-v1-14.html |date=2016-12-12 }}. International Dark-Sky Association (2000)</ref> many lighting professionals continue to disparage low-pressure sodium, contributing to its decreased acceptance and specification in lighting standards and therefore its use. According to Narisada and Schrueder (2004), another disadvantage of low-pressure sodium lamps is that some research has found that many people find the characteristic yellow light to be less pleasing aesthetically, although they caution that this research isn't thorough enough to draw conclusions from.<ref>{{cite book |last1=Narisada |first1=Kohei |last2=Schreuder |first2=Duco |title=Light Pollution Handbook |date=2004 |publisher=Springer Science & Business Media |isbn=978-1-4020-2665-2 |page=605 |url=https://books.google.com/books?id=61B_RV3EdIcC&pg=PA605 |language=en |access-date=2023-03-19 |archive-date=2023-09-18 |archive-url=https://web.archive.org/web/20230918112521/https://books.google.com/books?id=61B_RV3EdIcC&pg=PA605 |url-status=live }} "When, however, people were asked whether they liked the lighting, the general opinion was that the low pressure sodium lighting was "ugly” or “eerie”. The size of the study does not, however, permit robust conclusions."</ref>

Because of the increased sensitivity of the human eye to blue and green wavelengths when viewing low-luminances (the [[Purkinje effect]]) in the night sky, different sources produce dramatically different amounts of visible [[skyglow]] from the same amount of light sent into the atmosphere. To reduce light pollution caused by blue light, it is necessary to adopt lamps that, while maintaining the same photopic luminous flux, produce minimal scotopic light, and at the same time establish specific restrictions on the emitted wavelengths, particularly by shifting the spectral flux towards the blue side of the scotopic band (below 440 nm), to protect star visibility and significantly reduce the impact of artificial night sky glow.<ref name=CIE2001>{{cite book |author=CIE |date=2001 |title=The CIE System of Physical Photometry Draft Standard 010.2/E}}
</ref>

The protected wavelength range, the "P-band", should focus between 440 and 540 nm to preserve star visibility and reduce light pollution in wavelengths harmful to scotopic vision, while using lamps that emit less light in this range can help minimize pollution without compromising star visibility and protect health and the environment.<ref name=Falchi2011articolo2>{{cite journal |last1=Falchi |first1=F. |date=2011 |title=Campaign of sky brightness and extinction measurements using a portable CCD camera |journal=Mon. Not. R. Astron. Soc. |volume=412 |issue=1 |pages=33–48|doi=10.1111/j.1365-2966.2010.17845.x |doi-access=free |bibcode=2011MNRAS.412...33F }}
</ref>

===Re-designing lighting plans===

In some cases, evaluation of existing plans has determined that more efficient lighting plans are possible. For instance, light pollution can be reduced by turning off unneeded outdoor lights, and lighting stadiums only when there are people inside. Timers are especially valuable for this purpose. One of the world's first coordinated ''legislative'' efforts to reduce the adverse effect of this pollution on the environment began in [[Flagstaff, Arizona]], in the U.S. There, more than three decades of ordinance development has taken place, with the full support of the population,<ref>[http://www.flagstaffdarkskies.org Flagstaff Dark Skies Coalition] {{Webarchive|url=https://web.archive.org/web/20110118055950/http://www.flagstaffdarkskies.org/ |date=2011-01-18 }}. Flagstaffdarkskies.org (2011-10-24). Retrieved 2011-12-03.</ref> often with government support,<ref>[http://www.coconino.az.gov/comdev.aspx?id=144&terms=lighting Coconino County Lighting and General Codes] {{webarchive|url=https://web.archive.org/web/20110721032922/http://www.coconino.az.gov/comdev.aspx?id=144&terms=lighting |date=2011-07-21 }}. Coconino.az.gov (2008-01-07). Retrieved 2011-12-03.</ref> with community advocates,<ref>[http://docs.darksky.org/AGM/2009/Luginbuhl.ppt Arizona IDA presentation on Lighting issues (PowerPoint)] {{webarchive|url=https://web.archive.org/web/20100706041538/http://docs.darksky.org/AGM/2009/Luginbuhl.ppt |date=2010-07-06 }}. darksky.org.</ref> and with the help of major local observatories,<ref>[http://www.lowell.edu/ Lowell Observatory] {{Webarchive|url=https://web.archive.org/web/20110302233420/http://www.lowell.edu/ |date=2011-03-02 }}. Lowell.edu. Retrieved 2011-12-03.</ref> including the [[United States Naval Observatory Flagstaff Station]]. Each component helps to educate, protect and enforce the imperatives to intelligently reduce detrimental light pollution.

One example of a lighting plan assessment can be seen in a report originally commissioned by the Office of the Deputy Prime Minister in the United Kingdom, and now available through the [[Department for Communities and Local Government]].<ref>{{cite web|title=Towards good practice|work=Lighting in the countryside|url=http://www.communities.gov.uk/publications/planningandbuilding/lighting|access-date = 2008-01-16| archive-url = https://web.archive.org/web/20080108232309/http://www.communities.gov.uk/publications/planningandbuilding/lighting| archive-date = January 8, 2008}} [[Department for Communities and Local Government]], United Kingdom.</ref> The report details a plan to be implemented throughout the UK, for designing lighting schemes in the countryside, with a particular focus on preserving the environment.

In another example, the city of [[Calgary]] has recently replaced most residential street lights with models that are comparably energy efficient.<ref>[http://www.calgary.ca/Transportation/Roads/Pages/Traffic/Traffic-signals-and-streetlights/Envirosmart-streetlight-retrofit/EnviroSmart-streetlight-retrofit.aspx The City of Calgary: Envirosmart Streetlight Retrofit Program] {{webarchive|url=https://web.archive.org/web/20120502014929/http://www.calgary.ca/Transportation/Roads/Pages/Traffic/Traffic-signals-and-streetlights/Envirosmart-streetlight-retrofit/EnviroSmart-streetlight-retrofit.aspx |date=2012-05-02 }}. calgary.ca</ref> The motivation is primarily operation cost and environmental conservation. The costs of installation are expected to be regained through energy savings within six to seven years.

The Swiss Agency for Energy Efficiency (SAFE) uses a concept that promises to be of great use in the diagnosis and design of road lighting, "''consommation électrique spécifique'' (''CES'')", which can be translated into English as "specific electric power consumption (SEC)".<ref>{{cite web |url=http://www.efficace.ch/f/IndexAktuell.html |title=S.A.F.E > Actualité |publisher=Efficace.ch |access-date=2010-09-04 |archive-date=2011-05-12 |archive-url=https://web.archive.org/web/20110512162225/http://www.efficace.ch/f/IndexAktuell.html |url-status=live }}</ref> Thus, based on observed lighting levels in a wide range of Swiss towns, SAFE has defined target values for electric power consumption per metre for roads of various categories. Thus, SAFE currently recommends an SEC of two to three watts per meter for roads less than ten metres wide (four to six for wider roads). Such a measure provides an easily applicable environmental protection constraint on conventional "norms", which usually are based on the recommendations of lighting manufacturing interests, who may not take into account environmental criteria. In view of ongoing progress in lighting technology, target SEC values will need to be periodically revised downwards.
[[File:110213 LED vs Sodium vs Mercury.jpg|thumb|Crossroad in Alessandria, Italy: [[luminaire]]s with [[Mercury Lamp|mercury lamps]] are in the background, [[LED street light]]s in the middle, [[luminaire]]s with [[high pressure sodium lamp]]s are in the foreground.]]

A newer method for predicting and measuring various aspects of light pollution was described in the journal [[Lighting Research & Technology]] (September 2008). Scientists at [[Rensselaer Polytechnic Institute]]'s Lighting Research Center have developed a comprehensive method called Outdoor Site-Lighting Performance (OSP), which allows users to quantify, and thus optimize, the performance of existing and planned lighting designs and applications to minimize excessive or obtrusive light leaving the boundaries of a property. OSP can be used by lighting engineers immediately, particularly for the investigation of glow and trespass (glare analyses are more complex to perform and current commercial software does not readily allow them), and can help users compare several lighting design alternatives for the same site.<ref>[http://newswise.com/articles/view/544092/ Lighting Research Center Develops Framework for Assessing Light Pollution] {{Webarchive|url=https://web.archive.org/web/20110512173038/http://newswise.com/articles/view/544092/ |date=2011-05-12 }} Newswise. Retrieved 2008-09-08.</ref>

In the effort to reduce light pollution, researchers have developed a "Unified System of Photometry", which is a way to measure how much or what kind of [[street light]]ing is needed. The Unified System of Photometry allows light fixtures to be designed to reduce energy use while maintaining or improving perceptions of visibility, safety, and security.<ref>{{cite journal |doi=10.1191/1365782804li114oa |author=Rea, M. |author2=J.D. Bullough |author3=J.P. Freyssinier |author4=A. Bierman |name-list-style=amp |date=2004 |title=A proposed Unified System of Photometry |journal=Lighting Research and Technology |volume=36 |issue=2 |pages=85–111 |s2cid=14721508 }}{{Dead link|date=July 2018 |bot=InternetArchiveBot |fix-attempted=yes }}</ref> There was a need to create a new system of light measurement at night because the biological way in which the eye's rods and cones process light is different in nighttime conditions versus daytime conditions. Using this new system of photometry, results from recent studies have indicated that replacing traditional, yellowish, [[High pressure sodium|high-pressure sodium]] (HPS) lights with "cool" white light sources, such as induction, [[Fluorescent lamp|fluorescent]], [[Ceramic discharge metal halide lamp|ceramic metal halide]], or [[LED]]s can actually reduce the amount of electric power used for lighting while maintaining or improving visibility in nighttime conditions.<ref>{{cite journal|last1=Rea|first1=M.|last2=Yuan|first2=Z.|last3=Bierman|first3=A.|title=The unified system of photometry applied to remote airfield lighting|journal=Lighting Research and Technology|volume=41|pages=51–70|date=2009|doi=10.1177/1477153508095735|s2cid=111174811}}</ref>

The [[International Commission on Illumination]], also known as the CIE from its French title, la Commission Internationale de l'Eclairage, will soon be releasing its own form of unified photometry for outdoor lighting.

===Dark sky reserves===
{{main|Dark-sky preserve}}
In 2001 International Dark Sky Places Program was founded in order to encourage communities, parks and protected areas around the world to preserve and protect dark sites through responsible lighting policies and public education. As of January 2022, there are 195 certified International Dark Sky Places in the world.<ref>{{Cite web|url=https://www.darksky.org/our-work/conservation/idsp/|title=International Dark Sky Places|access-date=2022-04-18|archive-date=2022-04-20|archive-url=https://web.archive.org/web/20220420170943/https://www.darksky.org/our-work/conservation/idsp/|url-status=live}}</ref> For example, in 2016 [[China]] launched its first dark sky reserve in the [[Tibet Autonomous Region]]'s [[Ngari Prefecture]] which covers an area of 2,500 square kilometers. Such areas are important for astronomical observation.<ref>{{Cite web|url=https://www.chinadaily.com.cn/china/2016-06/21/content_25791823.htm|title=China's first dark sky reserve launched in Tibet[1]- Chinadaily.com.cn|website=www.chinadaily.com.cn|access-date=2022-04-18|archive-date=2022-04-18|archive-url=https://web.archive.org/web/20220418173418/https://www.chinadaily.com.cn/china/2016-06/21/content_25791823.htm|url-status=live}}</ref>

=== Community Involvement ===
Community awareness is also necessary in order to progress towards reducing light pollution. As if more people are aware on the effects of artificial lighting, there could be effective legislative influence on mitigating it. Unfortunately, there are groups that may still not be completely knowledgeable on its various impacts. For example, cultural beliefs may be the reason some are holding back; around the world, darkness may be associated with evil whereas light would contrastingly be associated with progress in some cultures.<ref>{{Cite journal |last=Pothukuchi |first=Kameshwari |date=2021 |title=City Light or Star Bright: A Review of Urban Light Pollution, Impacts, and Planning Implications |url=http://journals.sagepub.com/doi/10.1177/0885412220986421 |journal=Journal of Planning Literature |language=en |volume=36 |issue=2 |pages=155–169 |doi=10.1177/0885412220986421 |issn=0885-4122 |access-date=2024-04-09 |archive-date=2024-04-09 |archive-url=https://web.archive.org/web/20240409150918/https://journals.sagepub.com/doi/10.1177/0885412220986421 |url-status=live |url-access=subscription }}</ref> Furthermore, societal standards have made humans more active during the day time,<ref>{{Cite book |title=Ecological consequences of artificial night lighting |publisher=Island Press |year=2006 |editor-last=Rich |editor-first=Catherine |editor-last2=Longcore |editor-first2=Travis}}</ref> which may be another significant reason for the delay of increased knowledge and awareness. However, more recent studies show the public not only becoming more aware of the issue, but are also experiencing consequences of excessive artificial lighting.<ref>{{Cite journal |last1=Lyytimäki |first1=Jari |last2=Rinne |first2=Janne |date=2013 |title=Voices for the darkness: online survey on public perceptions on light pollution as an environmental problem |url=http://www.tandfonline.com/doi/abs/10.1080/1943815X.2013.824487 |journal=Journal of Integrative Environmental Sciences |language=en |volume=10 |issue=2 |pages=127–139 |doi=10.1080/1943815X.2013.824487 |issn=1943-815X |access-date=2024-04-09 |archive-date=2024-04-09 |archive-url=https://web.archive.org/web/20240409150918/https://www.tandfonline.com/doi/abs/10.1080/1943815X.2013.824487 |url-status=live }}</ref> An assessment from 2020 shows an increase in citizen awareness in the late 20th century due to availability to internet search engines as well as the ability to engage globally. The assessment discussion further suggests that better information accessibility and voting may motivate more citizens to understand and thus care about the issue.<ref>{{Cite journal |last1=Zielińska-Dabkowska |first1=Karolina M. |last2=Xavia |first2=Kyra |last3=Bobkowska |first3=Katarzyna |date=2020 |title=Assessment of Citizens' Actions against Light Pollution with Guidelines for Future Initiatives |journal=Sustainability |language=en |volume=12 |issue=12 |pages=4997 |doi=10.3390/su12124997 |doi-access=free |bibcode=2020Sust...12.4997Z |issn=2071-1050 }}</ref>

=== Dark infrastructure ===
{{Main|Dark infrastructure}}

Dark infrastructure is the creation and preservation of networks of natural levels of darkness, in an attempt to mitigate and reduce the adverse effects of artificial light on biodiversity. Implementation includes identifying and preserving existing dark networks as well as reducing artificial light at night.<ref>{{Cite journal |last1=Sordello |first1=Romain |last2=Busson |first2=Samuel |last3=Cornuau |first3=Jérémie H. |last4=Deverchère |first4=Philippe |last5=Faure |first5=Baptiste |last6=Guetté |first6=Adrien |last7=Hölker |first7=Franz |last8=Kerbiriou |first8=Christian |last9=Lengagne |first9=Thierry |last10=Le Viol |first10=Isabelle |last11=Longcore |first11=Travis |last12=Moeschler |first12=Pascal |last13=Ranzoni |first13=Jessica |last14=Ray |first14=Nicolas |last15=Reyjol |first15=Yorick |date=2022-03-01 |title=A plea for a worldwide development of dark infrastructure for biodiversity – Practical examples and ways to go forward |url=https://linkinghub.elsevier.com/retrieve/pii/S0169204621002954 |journal=Landscape and Urban Planning |volume=219 |pages=104332 |doi=10.1016/j.landurbplan.2021.104332 |bibcode=2022LUrbP.21904332S |issn=0169-2046}}</ref>