Light Pollution

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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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• 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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• Its sources include:– Building exterior and interior lighting– Advertising– Commercial properties– Offices– Factories– Streetlights– Illuminated sporting venues

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Types of Light Pollution

• Following are the types of light pollution– Light trespass– Over-illumination– Glare– Light clutter– Sky glow

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Light Trespass

Light trespass occurs when unwanted light enters one’s property

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Over-illumination

Excessive use of light

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Sky glow

The glow effect that you can see over populated areas

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Light Clutter

Excessive groupings of lights

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Glare

When there is an excess of contrast between dark and light areas in one’s field of view

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Effects of Light Pollution

• Light pollution has effect on– Natural resources and Environment– Humans– Animals

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• 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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• These gases then create– Green house gas melting polar caps, change in

weather pattern, stress on eco-system, increase in CO2

– 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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• Light pollution has adverse effects on humans– Lack of melatonin hormone

production by pineal gland in brain due to presence of light

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• 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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– 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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• Birds– 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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• 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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– 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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• 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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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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