A short presentation on what light pollution is and how it can be resolved.

1. Light Pollution
Environmental
Science
Group No. 5
• Rabeesh Kr. Gola
• Ankit Maity
• Vaibhav Maggo
• Ayush Mishra

2. Contents
 Introduction
 Types of Light Pollution
 Types (contd.)
 Causes
 Effects
 Ways to Mitigate
 Conclusion
 References

3. Introduction
 What is Light Pollution?
 Light pollution is excessive, misdirected, or obtrusive
artificial (usually outdoor) light. Too much light pollution
has consequences: it washes out starlight in the night sky,
interferes with astronomical research, disrupts
ecosystems, has adverse health effects and wastes energy.
A little more than 100 years ago, you could walk outside at
night even in a city and see the Milky Way galaxy arch
across the night sky. Being able to see thousands of stars
was part of everyday life, inspiring artists like Van Gogh or
musical composers like Holst or writers like Shakespeare.
By allowing artificial lights to wash out our starry night
skies, we are losing touch with our cultural heritage (e.g.,
what has made us who we are). We are also losing touch
with what could inspire future generations.

4. TypesofLightPollution
Three main types of light pollution include:
1. Glare
2. Light Trespass
3. Skyglow

5. Types(contd.)
 Glare from unshielded lighting is a public-health
hazard—especially the older you become. Glare light
scattering in the eye causes loss of contrast, sometimes
blinds you temporarily and leads to unsafe driving
conditions, for instance.
 Light trespass occurs when unwanted light enters one’s
property, for example, by shining unwanted light into a
bedroom window of a person trying to sleep.
 Skyglow refers to the glow effect that can be seen over
populated areas. Skyglow is the combination of all the
reflected light and upward-directed (unshielded) light
escaping up into the sky (and for the most part,
unused). …Shielding lights significantly reduces all
three of these types of light pollution.

6. Causes
 Poor Planning – The placement of signage and street
lights is planned by engineers, if they do not take into
account the effect placement has on the surrounding
environment they can create glare, light trespass and
light clutter.
 Irresponsible use – You may love Christmas lights but
leaving them on all night is a form of pollution, as is
leaving a room with the lights still on or setting the
timers on streetlamps and not adjusting the timer for
the season. Not actively choosing to minimize energy
waste is a huge source of light pollution.
 Overpopulation – That is really a zoning issue. Too
many businesses, or too many residences, grouped in
one area can cause light pollution of many kinds.

7. Effects
 In disrupting ecosystems, light pollution poses a serious threat in
particular to nocturnal wildlife, having negative impacts on plant and
animal physiology. It can confuse the migratory patterns of animals,
alter competitive interactions of animals, change predator-prey
relations, and cause physiological harm. The rhythm of life is
orchestrated by the natural diurnal patterns of light and dark; so
disruption to these patterns impacts the ecological dynamics.
 With respect to adverse health effects, many species, especially humans,
are dependent on natural body cycles called circadian rhythms and the
production of melatonin, which are regulated by light and dark (e.g., day
and night). If humans are exposed to light while sleeping, melatonin
production can be suppressed. This can lead to sleep disorders and other
health problems such as increased headaches, worker fatigue, medically
defined stress, some forms of obesity due to lack of sleep and increased
anxiety. And ties are being found to a couple of types of cancer. There
are also effects of glare on aging eyes. (See text below.) Health effects
are not only due to over-illumination or excessive exposure of light over
time, but also improper spectral composition of light (e.g., certain colors
of light).
 With respect to energy wastage, lighting is responsible for at least one-
fourth of all electricity consumption worldwide. Over illumination can
constitute energy wastage, especially upward directed lighting at night.
Energy wastage is also a waste in cost and carbon footprint.

8. WaystoMitigate
 1. Reduce the use decorative lighting. Festivities and celebration periods often leads to the
excessive use of decorative lighting kept on all day and night. The use of decorative
lighting during festive seasons should thus be lessened to reduce the brightening of the
skies. As an alternative, environmentally friendly candles should be used for the
celebration periods. Furthermore, it will also help in conserving energy.
 2. Use of covered bulbs that light facing downwards. For street lights – streets and
highways lighting must be properly designed such that too much light is not reflected into
the sky. The solution for this is designing covered bulbs that light facing downwards and
for this reason, it would help reduce the brightening of the skies as it eliminates the light
that reflects into the sky.
 3. Minimizing the use of lights. Switching off unnecessary lights can hugely help in
reducing light pollution. This is the cheapest, easiest and most effective method of dealing
with the problem. It can be achieved by turning off lights when about to sleep or whenever
there is no activity going on outside is the house. If the concern is security, then lights
should only be put on if there is a security alarm.
 4. The use of automatic systems to turn off street light at certain times. In the daytime,
there is no need for street lighting. Also, when the moon shines bright, there is no need for
street lighting. Automated timers and systems can be used to turn off street and highway
lights when they are not needed to encourage natural lighting. They can be pre-set to turn
off automatically whenever the environment is naturally bright.
 5. Refrain from light trespassing. The use of bright outdoor lights directed towards
neighboring houses is completely unethical because it creates discomfort. Therefore, it
must be ensured that outdoor lights do not trespass into residential houses. It is as simple
as ensuring the lighting in your house or street lighting projects do not allow light to enter
the neighboring houses. It is annoying and is even associated with creating sleep
disorders. In short, refrain from using outdoor lights that glare at neighbor’s window.
 6. Preventive measures are always important. Preventive measures are essential and
have to be taken whenever possible to reduce light pollution. Examples include the use of
glare-free bulbs, installing low hanging bulbs, having the lights facing downwards, and
covering the bulbs to reduce bright skies at night.

9. Conclusion
 Light pollution affects every citizen. It is a serious environmental
concern that wastes money and resources while jeopardizing wildlife,
our environment, health, and human heritage. Each of us can
implement practical solutions to combat light pollution locally,
nationally, and internationally.
 The negative effects of the loss of this inspirational natural resource
might seem intangible. But a growing body of evidence links the
brightening night sky directly to measurable negative impacts on
human health and immune function, on adverse behavioural changes
in insect and animal populations, and on a decrease of both ambient
quality and safety in our night-time environment. Astronomers were
among the first to record the negative impacts of wasted lighting on
scientific research, but for all of us, the adverse economic and
environmental impacts of wasted energy are apparent in everything
from the monthly electric bill to global warming.
 In refreshing contrast to some of today’s complex and lingering
environmental problems, many existing solutions to light pollution
are simple, cost-effective, and instantaneous. Recognizing when
outdoor lighting no longer serves its function and becomes a pollutant
is the first step toward choosing appropriate solutions.

10. References
Books
 At Days Close; Night in Time Past – Roger A Kirch
(2005)
 Ecological Consequences of Artificial Night Lighting –
Catherine Rich (2006)
Websites
 https://en.wikipedia.org/wiki/Light_pollution
 https://www.conserve-energy-future.com/impressive-
ways-reduce-light-pollution.php
 https://edition.cnn.com/2017/11/23/health/light-
pollution-increase-study/index.html
 https://www.conserve-energy-future.com/types-
causes-and-effects-of-light-pollution.php
 https://www.globeatnight.org/light-pollution.php

11. THANK YOU