Running Head: MANAGEMENT OPTIONS FOR REDUCING LIGHT POLLUTION
Management Options for Reducing Light Pollution
Sophia Tsang
SHSID
MANAGEMENT OPTIONS FOR REDUCING LIGHT POLLUTION
Introduction
Statement of the Problem
Light pollution is an international concern throughout the world, with nearly 80% of the world’s
population living under light-polluted skies. Light pollution is caused by the excessive use of
light – especially outdoor light, disrupting the natural day-night pattern by pollution the night sky
with light. The level of light pollution caused by outdoor light increases around 20% per year
globally, and not only is it disrupting astronomical programs, but also having negative effects on
the environment, ecological systems and the health of almost all living organisms as a whole.
Purpose of the Study
Light pollution is a very present problem that many people believe to have insubstantial
consequences on society. By understanding the true nature of the negative effects of light
pollution, and researching ways to reduce it, the student will gain more awareness to the problem
at hand. Though light pollution may seem to only effect the night sky and not the humans and
living organisms around it, light pollution actually effects many unknown aspects of living
organisms’ lives. For humans, the production of artificial light and light pollution increases the
risk of dangers during driving whilst also effecting other aspects of human health, interfering
with astronomical research – delaying the progress of discoveries, along with disrupting
ecosystems and wasting energy through producing excessive amounts of artificial, electrical
light. Yet, these are only some of the many unknown effects of light pollution, and through this
research, the reader will gain more awareness of the full extent of light pollution’s influence
through a larger perspective of consequences on humans, living organisms and ecosystems.
Significance of the Problem
In many ways, light pollution has a negative effect on daily life around humans. An example of
MANAGEMENT OPTIONS FOR REDUCING LIGHT POLLUTION
these negative consequences of the production of artificial light can be seen through the
condition produced called ‘disability glare’, which reduces the awareness of drivers during
driving. Through the reduction of light pollution, the hazard of distracted driving will also be
reduced, therefore creating a safer driving environment. Internally, light pollution also disrupts
our circadian rhythms, melatonin levels and contributes to sleeping disorders due to disrupting
normal sleep patterns and hormone regulation. Also, light pollution consumes a huge portion of
the world’s energy, therefore wasting valuable energy whilst releasing millions of tons of carbon
dioxide into the air. Overall, by reducing light pollution, humans will be able to: conserve a huge
portion of energy consumption throughout the world, reduce the rate of physiological disorders
and related long-term health issues, protect nocturnal wildlife, reduce the amounts of
photochemical smog, etc.
Theoretical Framework
Light pollution stems from the excessive use of artificial light – a side effect of modern
industrialization. Components of light pollution includes glare - excessive brightness that leads
to visual discomfort, skyglow – brightening of the night sky over inhabited areas, light trespass –
light falling (reflecting) where it is not intended, and clutter – bright and excessive groupings of
light sources. The main source of light pollution stems from outdoor lighting used at night, as the
light is poorly targeted, reflecting and spilling into the night sky, resulting in light trespass. Due
to a huge portion of outdoor lights producing excessive artificial lights that causes light trespass,
it also contributes in wasting large amounts of energy consumed during the process of providing
light sources. Also, the consequences of light trespass and skyglow stem form the amount of
excessive light being reflected into the night sky, destroying nitrate radicals which contributes in
increasing photochemical smog – a type of smog produced when ultraviolet light from the sun
reacts with nitrogen oxides in the atmosphere (Afework, Donev, Hanania & Stenhouse 2018) –
MANAGEMENT OPTIONS FOR REDUCING LIGHT POLLUTION
increasing atmospheric pollution.
Research Questions
Though light pollution is very present in the current modernized and industrialized societies, it is
still an environmental danger many people believe to be insubstantial, therefore the question;
“What is the full extent of the negative consequences of light pollution on living organisms and
ecosystems?” is very common in daily society. By giving more insight into this question, the
awareness for the severity of light pollution will increase. One of the first questions to ask when
learning about the consequences of artificial light production is how the process of light pollution
occurs; “What is the science behind light pollution?”. As finding out how light pollution is
produced will lead to finding out how to reduce the amount of artificial light present in the
atmosphere. Finally, the general public also needs the question – “Is it possible to reduce light
pollution?” – to be answered in order to fully concede into taking action in reducing this danger.
Hypothesis
As light pollution mainly exists due to the excessive use of wasted artificial lighting and the
mistargeting of nighttime electric lights, by solving the problem of how to prevent light trespass,
we will also be able to find management options for reducing light pollution. By using fully
shielded lighting to prevent the direct upward emission of light, the amount of excess light
reflected into the night sky will also be significantly reduced. Also, by reducing the amount of
lights emitted in the bluer spectrum, the amount of photochemical released and the overall glare
and skyglow produced will decrease. Emitted ‘blue light’ from artificial lights are a problem
with consequences including disrupting sleep patterns and causing sleep disorder. Due to the
production of photochemicals attributing to the increase of light pollution, it can be concluded
that by reducing the amount produced, humans can also reduce the amount of light pollution.
MANAGEMENT OPTIONS FOR REDUCING LIGHT POLLUTION
Research
“Many environmentalists, naturalists, and medical researchers consider light pollution to
be one of the fastest growing and most pervasive forms of environmental pollution” (Chepesiuk
2009). One of the main contributors in producing skyglow is direct upward emission of light – in
which light is reflected directly into the night sky – therefore by reducing the amount of direct
emission, the amount of skyglow would reduce by an average of 50%. This factor links with the
incorrect targeting of light, in which light trespass occurs due to light being reflected into
unwanted areas. The amount of electric light being reflected upward is scattered by the water,
dust and gas molecules in the atmosphere, producing skyglow. In lit urban areas, the production
of skyglow is extended to effect unlit areas, emitting significant amounts of light. The most
common source of direct upward light emission is public street lighting, as it provides the most
intense source of lighting in urban areas. According to the International Energy Agency in 2006,
street lighting also uses up around 114 TWh (114,000 GWh) of energy globally (Bennie, Davies,
Gaston & Hopkins 2012). In the US alone, around 22 TWh (22,000 GWh) of energy is wasted on
artificial light production, costing around $2.2 billion annually (Filmer 2013).
Currently, changes in street lighting include altering the spectrum at which light was
produced, replacing the primarily blue emitted light with more yellow, warmer sources, allowing
for better rendering for human vision, therefore resulting in less human visual discomforts and
distractions. Reducing the time and intensity of light exposure to reduce light trespass has also
been considered in order to decrease the amounts of carbon emissions and light pollution. LED
(light emitting diode) lamps have also become more cost-effective, along with the value of
emitting warmer colored light, has allowed for its popularity to rise. Other factors to consider
when using artificial light are the influences of the light’s properties to organisms’ behaviors and
health. Almost all living organisms heavily rely on their sensitivity to the properties of light,
therefore, the usage of light should also consider the basis for an ecological compatibility
MANAGEMENT OPTIONS FOR REDUCING LIGHT POLLUTION
(Bennie, Davies, Gaston & Hopkins 2012).
As the sensitivity towards light is a heavy reliance effecting organisms’ behavior, the
influences and consequences of artificial light on the subconscious, internal human is no
different. “A growing body of scientific research suggests that light pollution can have lasting
adverse effects on both human and wildlife health” (Chepesiuk 2009). The intensity and
spectrum at which artificial light is produced can cause visual discomfort to the exposed retina,
internally disrupting the circadian rhythm and melatonin production, disrupting sleep patterns.
Too much retinal exposure to the photons emitted from artificial light may disrupt the circadian
rhythm – which are physical, mental and behavioral changes of a living organism that follows a
daily cycle, responding primarily to the light and darkness of the environment. Therefore, too
much light exposure will disrupt the circadian rhythm by producing the wrong amount of
regulation to an organism’s circadian cycle. Many behavioral changes regulated by an
organism’s circadian cycle includes; triggering “seasonal phenological events such as bud burst,
flowering and senescence… to infer the position of leaves within a canopy; and as a directional
cue for navigation” (Bennie, Davies, Gaston & Hopkins 2012). Therefore, it is seen that the
excess light exposure produced from skyglow and light trespass heavily interferes with the
organisms’ daily life patterns and cycles, even disrupting their survival patterns completely.
The ecological effects of light pollution from excessive use of artificial light have been
shown in both flora and fauna, affecting all living organisms to an extent. “Research on insects,
turtles, birds, fish, reptiles, and other wildlife species shows that light pollution can alter
behaviors, foraging areas, and breeding cycles, and not just in urban centers but in rural areas as
well” (Chepesuik 2009). These negative effects of light trespass and skyglow on living
organisms can be seen through the example of sea turtles. Even at birth, sea turtle hatchlings rely
on the amount of light to determine the sea’s location – relying on light for their survival. Most
female sea turtles lay their eggs on beaches, but due to the excess amount of lights illuminating
MANAGEMENT OPTIONS FOR REDUCING LIGHT POLLUTION
from the beaches and nearby urban centers, these turtles are discouraged from nesting in these
areas, resulting in lesser amounts of plausible habitable areas for laying eggs. To add on, sea
turtle hatchlings navigate towards the sea by orienting towards the light source of the ocean,
determining land through its elevated, dark silhouette. Yet, due to the excess amounts of artificial
lights trespassing onto the beach and illuminating from urban centers nearby, the hatchlings
become disorientated, therefore navigating away from the sea, resulting in the decrease of their
survival rates as they will never find the sea. Turtles are not the only wildlife heavily affected by
artificial light usage during night. Artificial electric lights disrupt the behavior of birds, as the
lights produced from buildings and structures disrupt their migration patterns at night. “Each
year in New York City alone, about 10,000 migratory birds are injured or killed crashing into
skyscrapers and high-rise buildings” (Chepesuik 2009). The production of artificial light has also
inhibited mating cycles, disrupted feeding habits, and destroyed habitats of many animals, etc.
Physiological health effects and consequences of light pollution do not exclude humans,
though its effects have not been as well defined. In further detail to the light pollution’s effect on
human’s circadian cycle, not only does it regulate behavioral, mental and physical changes of all
living organisms including humans, “studies [also] show that the circadian cycle controls from
ten to fifteen percent of our genes” says Paolo Sassone-Corsi, chairman of the Pharmacology
Department at the University of California, Irvine. The circadian clock, a 24-hout day to night
cycle, effects physiologic processes in almost all living organisms, including the regulation of
brain wave patterns, hormone patterns, cell regulation, etc. Mentally, disrupting a human’s
circadian cycle will link to medical disorders including depression, insomnia, cardiovascular
disease and cancer – proven as scientists have seen that over-exposure to artificial light may
disrupt neuroendocrine physiology, accelerating tumor growth by disrupting hormone production
and regulation of cell growth. Due to artificial light production and light pollution extending the
period of daytime in many countries, the body’s normal cycle of producing melatonin and other
MANAGEMENT OPTIONS FOR REDUCING LIGHT POLLUTION
hormones for sleep is prolonged, fitting the extended period of day, decreasing the amount of
time for a human’s sleep cycle. The disruption of the sleep cycle can be linked to the disability to
establish a regular activity cycle, which therefore – according to lead researcher Douglas
McMahon of the Vanderbilt University researchers - may contribute in the increased risk of
depression and other mood disorders (Chepesuik 2009).
Many management and reduction options for night-time light pollution have been
proposed and explored – preventing areas from being artificially lit, limiting the light duration,
reducing light trespass, changing the intensity and spectrum of the lighting, etc. (Bennie, Davies,
Gaston & Hopkins 2012). Each having their own ecological impacts, whether positive or
negative. By maintaining naturally unlit areas (unaffected by light trespass), the amount of light
pollution produced would become more localized – in urban centers. Though this may have a
significant effect on the localized organisms’ behavior, the spread of skyglow will still have a
wide range to spread beyond the localized artificial lighting zone, reaching unlit areas and
spreading light pollution. Different light intensities and spectrums may have different effects on
an organism’s health, for instance, the more blue (cooler color temperature) the spectrum of the
light emitted is, the less the ability for the retina to render the light is. The more intense the light
emitted is, the more disruptive it will be for an organism’s circadian rhythm and sleep patterns. It
is scientifically proven that emitted blue light is very effective in inhibiting melatonin produce,
reducing the quality and quantity of a living organism’s sleep. Therefore, by reducing the amount
of blue artificial light emitted during the night, the better performance one’s body will have due
to having better behavioral, mental and physical changes based on reaction. Another aspect to be
considered when producing the ideal outdoor lightings, is its consumption rate of global energy.
Heavy portions of energy consumed closely relates to the heavy production and release of carbon
dioxide into the atmosphere, contributing in the increase of light and atmospheric pollution.
As light trespass and skyglow are produced due to the mistargeting of artificial light
MANAGEMENT OPTIONS FOR REDUCING LIGHT POLLUTION
during nighttime, the reduction of light trespass through using fully shielded lighting (downward
facing light that do not emit above a 45-degree angle) will contribute massively in reducing the
amount of skyglow produced – therefore reducing light pollution production as a whole. Though
the ideal use of fully shielded lighting is to prevent a large portion of upward emitted light to be
reflected into the night sky, an aspect regarding the range of ground distance within the target
area covered by the downwards emitted light should be considered. The ideal fully shielded
lighting will be able to both prevent direct upwards emission of light, while still allowing a large
range of the target area to be illuminated by the downwards emitted light. There are many
benefits of using fully shielded lighting; reducing the amount of wasted light, decreasing the
amount of skyglow and light trespass and emitted more illuminated light in one targeted area.
‘Wasted light’ is defined as light that is reflected in nontargeted areas (unlit areas), a byproduct
of light trespass, estimating at 30% of artificial street lighting during night (which is estimated in
the US alone to have cost 22,000 gigawatt-hours per year of energy). “This translates into an
unnecessary annual release of over 15.5 million metric tons of greenhouse gases – that’s the
equivalent to the amount released by seven years of electric usage from all the homes in the U.S”
(Filmer 2013). The usage of fully shielded lighting can both lessen the amount of light trespass
produced during the night and also reduce the usage of energy on ‘wasted light’.
Experiment
Experimental Procedure
The results gathered from the experiment will mainly be based off of qualitative observation, as
there are not enough materials to gather accurate quantitative data. The experiment by its own
will show the relationship between the reflection of light and the use of fully shielded lighting.
The best outdoor light source for nighttime use should maximize the comfortability of the
retina’s rendering of the light, should provide good amounts of emitted light in a specific
MANAGEMENT OPTIONS FOR REDUCING LIGHT POLLUTION
targeted area and should conserve as much energy as possible. Testing all three aspects of an
ideal outdoor light source would require three different experiments, therefore the most
important aspect of reducing light trespass – the amount of light shielded – will be tested in the
experiment. Data will be observed in a dark room and collected through the amount and intensity
of light reflected onto the targeted area and amount of light reflected out of the targeted area. The
amount of targeted area will be measured and compared to each type of shielding and the amount
of upward emitted light will be observed.
1. A poorly shielded lamp was set up on a flat surface in a dark room with no other light
sources present. (The lamp had 0.2 cm shielding below the bottom of the light bulb and
emitted 40W).
2. The circular target area was set directly underneath the light. A ruler was placed in the
target area, (in which the zero offset was on the target area’s center and extended
outwards).
3. The control group – a poorly shielded lamp with 0.2 cm shielding below the light bulb
and a diameter of 12.5 cm – was measured first, measuring both the distance that the light
emitted spread and observing the amount of light was emitted upwards.
4. The first experimental group – a shielded lamp with 5 cm shielding below the light bulb
and a diameter of 12.5 cm – was tested and observed.
5. The second experimental group – a shielded lamp with 10 cm shielding below the light
bulb and a diameter of 12.5 cm – was tested and observed.
6. The third experimental group – a shielded lamp with 0.2 cm shielding below the light
bulb and a diameter of 30 cm – was tested and observed
7. The measured and observed data; distance of light emission in the targeted area and the
amount of seen reflected upwards light in non-target areas, was compared to find trends
and to come up with a conclusion.
MANAGEMENT OPTIONS FOR REDUCING LIGHT POLLUTION
Variables
The set independent variable for the experiment on the effectiveness of fully shielded lighting is
the type of shielding used for the lamp. As the use of fully shielded lighting may better direct the
emission of light, it is a very important variable in the experiment. Therefore, any trends found in
the final results will be able to easily link back to the effects of using fully shielded lighting. The
dependent variable in the experiment is the measure of the amount of light emitted and reflected
into the target and non-target areas. As the dependent variable directly links to the independent
variable, any change with the amount of light emitted and reflected onto the target and beyond
that may directly relate to the effectiveness of fully shielded lighting. The dependent variable
heavily connects with the final results of the experiment, determining whether the hypothesis is
true or needs to be revisited. The constant variables of the experiment are; the type of light
source used and provided, the bulb wattage (40W) in which the light from the light source is
emitted, the same environment and conditions produced for each group (dark room, no external
light sources), same type of shielding material used, etc. Through the use of constant variables,
the final result will be more reliable, as there may be no outer influence on the experimental
procedure. Finally, the control group of the experiment will be the original, poorly shielded light
with 0.2 cm shielding and is 12.5 cm in diameter. The use of the control group is to compare the
final results with, but also to provide a realistic experience as these types of unshielded lights are
very commonly seen and used during nighttime. There will be three experimental groups (three
different types of shielding) – 5 cm shielding and 12.5 cm in diameter, 10 cm shielding and 12.5
cm in diameter and 0.2 cm shielding and 30 cm in diameter. Overall, the development of these
variables and groups will allow for the reliable and trustworthy final results produced.
Data Collection
The numbers provided in the following collected qualitative data are simple estimates at most,
MANAGEMENT OPTIONS FOR REDUCING LIGHT POLLUTION
therefore may not be exactly as accurate or precise as other factors. A ruler with a zero offset in
the target area and extending into the non-target area will measure the amount of light that
spreads. The amount of light reflected or directly emitted upwards is measured through
quantitative observation, categorizing the conditions of light trespass with four aspects – not lit,
dimly lit, moderately lit and fully lit. These three aspects will determine the amount of light
trespass is present when using that specific control or experimental group. These measured
qualitative observations and results of the experiment are represented in Figure 1 below.
Control Group
Experimental
Experimental
Experimental
(0.2 cm / 12.5
Group 1 (5 cm /
Group 2 (10 cm
Group 3 (0.2 cm
cm)
12.5 cm)
/ 12.5 cm)
/ 30 cm)
40 W
40 W
40 W
40 W
> 100 cm
30 cm
20 cm
50 cm
Fully Lit
Moderately Lit
Moderately Lit
Dimly Lit
Light Bulb
Wattage (W)
Emission of Light
in Target Area by
radius (cm)
Amount of Light
in Unlit Area
Figure 1. “Relationship between light shielding and the spread of emitted light beyond the target area”.
Data Analysis
Given the quantitative and qualitative data provided through the experiment, it is easy to connect
the relationship between the use of fully shielded light and the area that the emitted light spreads
MANAGEMENT OPTIONS FOR REDUCING LIGHT POLLUTION
and reflects to. Due to the control group not effectively controlling the direction of light that is
emitted, the emission of light extended far more outwards than expected in the target area,
upwardly distributing some of the light emitted into unlit areas. The control group represents
many commonly used shielding for nighttime outdoor use, representing the poorly controlled and
distributed light having its effect on the night sky. In both experiment groups 1 and 2, the vertical
length (height) is increased with the theory that the light emitted will be more targeted and
intense in one target area. The results (30 cm and 20 cm) showed that the light emitted was
accurately directed towards the target area, but the amount of upwards emitted light was still
present in both experiment groups, reflecting moderately lit light directly upwards. The limited
area produced through the longer length shielding was effective, but not efficient for covering
extended ground distances outdoors. Therefore, the final experiment group – experiment group 3
– was created with less length shielding and longer width shielding (being 17.5 cm wider in
diameter than the previous groups). The results from experiment group 3 were seen to be the
most ideal and effective for controlling light emissions. The downward light emitted covered a
more extended distance than the previous experiment groups covering around 25 cm more
distance when measuring the radius of the emitted light. The upward emission of light was also
more effectively controlled than the previous experimental and control groups, as the overall
lighting directed upwards was quantitatively observed to be comparably dimmer than the
previous tested groups. As experiment 3’s shielding allows light to be emitted into a wider range
of ground area, whilst still limiting the amount of light emitted directly upwards, it can be
concluded that a wider shielding is more effective in preventing upwards emission of light while
still allowing for a wide range of target areas to be covered by light.
Potential Implications
Under the basis of the varieties of shielding tested to prevent light trespass and overall, light
MANAGEMENT OPTIONS FOR REDUCING LIGHT POLLUTION
pollution, future developers of light shielding could undergo the same experiments to accurately
determine the best type of shielding in both preventing upwards emission of light and enabling a
wider range of downwards emission of light in targeted areas. By spreading the awareness that a
shielding with a greater width would be the most ideal for ideal light emission, the general public
may be able to be more careful when looking for outdoor lights, understanding what each type of
shielding for these lights could provide in effectiveness of emission. Design companies of light
shielding could also follow this basis to develop better ways of effectively preventing light
trespass.
Future studies include testing the other two variables for reducing the amount of light
pollution; the effect of color temperatures and spectrums in emitted light on human health, and
different types of light sources on energy conservation. By testing color temperatures and
spectrums for light with the wider shielding, we can determine which color temperature (warmer
or cooler) is most comfortable for the retina to render, and which color temperature would be the
most ineffective and visually impairing. The results from this experiment will allow for an ideal
amount of outdoor lights with visually comfortable lighting, allowing for the improvement of
physiological health during exposure to these lights. Testing the effect and consumption of
different types of light sources (for example LEDs) on the amount of energy used will also
provide results that lead to a more globally inclusion topic – how to conserve energy. The
consumption of global-use energy leads to a global consumption of money, equally effecting
both the economy and the people. Also, the miscalculated and poorly controlled emission of
wasted light is a big contributor to the consumption of energy, which also leads to a greater
portion of carbon dioxide being released into the air, leading to both light and atmospheric
pollution. Therefore, through these experiments, the most ideal type of lighting may be deduced
and concluded, in the aspects of; controlled targeting of light, the effects of these lights on health
and the effect of these lights on the global consumption of energy.
MANAGEMENT OPTIONS FOR REDUCING LIGHT POLLUTION
As there was a limited amount of resources for the production of the experiment on
controlled targeting of light, many aspects and variables of the experiment were not accurately
modeled to fit real outdoor lights. The placement of the light would be more centralized in a flat
area surrounding buildings to represent a street model, the ways of collecting qualitative and
quantitative data would be more precise and detailed than just the limited use of estimated
measurements and qualitative observations. Therefore, the results produced from these precise
measurements would be more reliable and concise overall. Finally, the model and technique used
for the different designs of light shielding would have been better developed to model and
represent commonly used outdoor streetlight shielding, to produce results more closely linked to
modern outdoor lighting. The material used to produce these shielding would also be modeled to
better suit and fit the lights. All these considered aspects and variables that should be improved
in a future study and experiment will allow for a more reliable and connected result, which will
be more definitely suitable for outdoor light production. The current aspects and variables used
in the current experiment were produced to model a commonly used outdoor lighting technique
as closely as possible, but with limited supplies and materials, the results may differ from more
accurate evaluations and experiments.
MANAGEMENT OPTIONS FOR REDUCING LIGHT POLLUTION
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