This document discusses light pollution, defining it as the alteration of natural light levels due to artificial light sources. It is most severe in densely populated, industrialized areas of North America, Europe, Japan, and major Middle Eastern and North African cities. Light pollution comes from various exterior and interior lighting sources and has negative effects on the natural environment, humans, and animals. It disrupts ecosystems, increases greenhouse gases, and harms wildlife navigation, behaviors, and food sources. The document recommends reducing light pollution by using dimmer, targeted lighting and motion sensors to turn off unnecessary fixtures.

1. Chapter
Light Pollution
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2. What is Light Pollution?
• Definition:
– Alteration of natural light levels in the outdoor
environment owing to artificial light sources
• It also known as photo-pollution or
luminous pollution
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3. • Light pollution is a side-effect of
urbanization
• It is most severe in highly
industrialized, densely populated areas
of:
– North America
– Europe
– Japan
– Major cities in the
• Middle East
• North Africa
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5. • Its sources include:
– Building exterior and interior lighting
– Advertising
– Commercial properties
– Offices
– Factories
– Streetlights
– Illuminated sporting venues
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6. Types of Light Pollution
• Following are the types of light pollution
– Light trespass
– Over-illumination
– Glare
– Light clutter
– Sky glow
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7. Light Trespass
Light trespass occurs when unwanted light
enters one’s property
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8. Over-illumination
Excessive use of light
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9. Sky glow
The glow effect that you can see over populated areas
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10. Light Clutter
Excessive groupings of lights
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11. Glare
When there is an excess of contrast between
dark and light areas in one’s field of view
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12. Effects of Light Pollution
• Light pollution has effect on
– Natural resources and Environment
– Humans
– Animals
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13. Natural Resources &
Environment
• The Environmental Protection
Agency says that
– Most electricity is used for lighting is
produced with coal and oil
• The emissions of burning coal and
oil include
– Carbon dioxide
– Sulfur dioxide
– Nitrogen dioxide
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14. • These gases then create
– Green house gas  melting polar caps, change in
weather pattern, stress on eco-system, increase in CO 2
– Acid rain  Toxic water, damages trees, stress on
eco-system, increase in SO2 and NO2
– Smog  Breathing problems, crops are damaged
• Moreover, much of the light produced is
wasted into the environment
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15. Humans
• Light pollution has adverse effects
on humans
– Lack of melatonin hormone
production by pineal gland in brain
due to presence of light
• Melatonin hormone is produced at night, when
there is complete darkness
– It has been shown to powerfully suppress tumor
growth in the body.
– It has strong antioxidant effects. This hormone is
also known to enhance healing and regenerative
processes within the body.
– Research suggests that it may help strengthen the
immune system.
– It helps initiate the sleep cycle. it is one of the
greatest natural cancer remedies.
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16. – Effect on circadian clock (24-hour
day/night cycle)
• Leads to sleep disorder
• Lower performance
– Increase eyesight problem in kids
– Increase level of anxiety
• Suicide rates increase
– Highest in Finland during 24-hour daylight in
summers
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17. • Birds
Animals
– At least, 100 million birds are killed
annually due to combination of
• Disorientation due to artificial lighting
• Bright light
• Towers with blinking beacons
– Bi-annual migration of birds is also
effected
• Use reflection of stars and moonlight to
guide their way. However, due to sky
glow birds are facing problems in finding
their way
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18. • Insects
– Any outdoor light is usually surrounded by
an assortment of insects because they are
attracted to light.
• Insects will fly around from light to light
gathering with other insects and are eventually
blinded, exhausted or overheated to death
– Studies show that the average street lamp
kills at least 150 insects each night it is lit.
• Multiply that by 365 and you get 54,750
insects killed by one lamp in a year.
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19. – Lesser insects may sound good, but it has
an adverse effect on the entire food
chain
• The birds, bats, reptiles and frogs depend on
these insects for survival
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20. • Sea Turtles
– Sea turtle eggs are buried in the beach by their
mothers and hidden for a period of time.
– When they hatch, the hatchlings are supposed to
crawl towards the water by looking for the
brightest horizon
– Use the reflection of moonlight and stars on the
water or the reflection of the sun on the water.
– However, due to light pollution, instead of heading
for the water, the hatchlings are disoriented and
heading for the cities and die from either
exhaustion, being hit by a car or other various
deaths
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21. How to Reduce Light Pollution?
• Following are the ways:
– By keeping lights dim
– Turn off unnecessary lights
– Use proper fixtures, which direct light to
specific objects
– Use light detectors or sensors
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