light pollution according to health, safety & environment

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Light Pollution

By: Muhammad Anwar Gul

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What is Light Pollution?

• Light pollution, also known as photo-pollution or luminous pollution, isexcessive or obtrusive artificial light.

• The International Dark Sky Association(IDA) defines light pollution as:

 – Any adverse effect of artificial light including

Sky glow, glare, light trespass, light clutter,decreased visibility at night, and energywaste.

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Sky Glow

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Sky Glow• Refers to the "glow" effect that is visible

over populated areas.

• It is the combination of all light reflected

from what it has illuminated escaping upinto the sky and from all of the badlydirected light in that area that alsoescapes into the sky.

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Sky Glow

• Sky glow particularly irritates astronomers,because it reduces contrast in the nightsky to the extent where it may even

become impossible to see any but thebrightest stars.

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Glare

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Glare• Types of Glare: 

 – Blinding glare describes effects such asthat caused by staring into the Sun. It iscompletely blinding and leavestemporary or permanent vision

deficiencies. – Disability glare describes blinded effects

by oncoming car lights, or lightscattering in fog or in the eye, reducingcontrast, as well as reflections from printand other dark areas that render thembright, with significant reduction in sightcapabilities.

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Glare

 – Discomfort glare  doesn’t typically cause

a dangerous situation however it isannoying and irritating. It can cause

fatigue if experienced over extendedperiods.

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Light trespass

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Light trespass

• Light trespass occurs whenunwanted light enters one'sproperty, for instance, byshining over a neighbour's

fence.

• A common light trespassproblem occurs when a strong

light enters the window of one'shome from the outside, causingproblems such as sleep

deprivation.

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Light Clutter

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Light Clutter

• Light clutter is excessivegroupings of lights. Groupingsof lights may generateconfusion, distract fromobstacles and potentially causeaccidents.

• Clutter is particularly noticeable

on roads where the street lightsare badly designed, or wherebrightly lit advertising surroundsthe roadways.

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Light Clutter

• Clutter may present a hazard in theaviation environment if aviation safetylighting must compete for pilot attentionwith non-relevant lighting.

 – For instance, runway lighting may beconfused with an array of suburban

commercial lighting and aircraft collisionavoidance lights may be confused withground lights.

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Effects of Light Pollution

Energy Waste Effects on human health & psychology

Disruption of Ecosystem

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Effects of Light Pollution

• Energy waste

• Effects on animal andhuman health andpsychology

• Disruption of ecosystems

• Effect on astronomy• Increase in atmospheric

pollution

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Energy waste

• Lighting is responsible for one-fourth of allelectricity consumption worldwide,[1]

• Case studies have shown that over-illumination constitute energy wastage,including non-beneficial upward direction

of night-time lighting.

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Energy waste

• In 2007, Terna (company managingelectricity flow in Italy), reported savings of645.2 million kWh in electricity

consumption during the daylight savingperiod from April-October. It attributes thissaving to the delayed need for artificial

lighting during the evenings.

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Effects on animal & human

health & psychology

• Medical research on the effects of excessivelight on the human body suggests that a varietyof adverse health effects may be caused by lightpollution.

• Health effects of over-illumination or improperspectral composition of light may include:increased headache incidence, worker fatigue,stress and increase in anxiety.[2] 

• Animal models have been studieddemonstrating unavoidable light to produceadverse effect on mood and anxiety.[3] 

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Disruption of Ecosystems

• Light pollution poses a serious threat to

wildlife, having negative impacts on plantand animal physiology. Light pollution canconfuse animal navigation, altercompetitive interactions, change predator-prey relations, and cause physiologicalharm.[4] 

• The rhythm of life is orchestrated by the

natural patterns of light and dark,disruption to these patterns impacts theecological dynamics.[5] 

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Effect on Astronomy

• Light trespass can impact observationswhen stray light enters the tube of thetelescope from off-axis, reflecting from

surfaces other than the telescope's mirrors(if any) so that it eventually reaches theeye piece, causing a glow across the field

of view since it has not been focused.

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Effect on Astronomy

• Sky glow reduces the contrast betweenstars and galaxies in the sky and the skyitself, making it more difficult to detect

fainter objects.

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 Increase in atmospheric

pollution• Light pollution destroys nitrate radicals

thus preventing the normal night time

reduction of atmospheric smog producedby fumes emitted from cars and factories.

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Reducing Light Pollution

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Reducing Light Pollution• Utilizing light sources of minimum intensity

necessary to accomplish the light'spurpose.

• Turning lights off using a timer or

occupancy sensor or manually when notneeded.

• Improving lighting fixtures, so that theydirect their light more accurately towardswhere it is needed, and with less sideeffects.

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Improving lighting fixtures

• Adjusting the type of lights used, so thatthe light waves emitted are those that areless likely to cause severe light pollution

problems.

• Evaluating existing lighting plans, and re-designing some or all of the plans

depending on whether existing light isactually needed

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Improving lighting fixtures

• The use of full cut-off lighting fixtures

reduces light pollution.

• Lights should be spaced appropriately formaximum efficiency, and that lamps within

the fixtures shouldn't be overpowered

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Actions for residential owners &builders

• Replace old fixtures with fully shieldedexterior lighting fixtures.

• Install fully lighted fixtures in new buildings

• Cut off exterior lighting fixtures aftermidnight

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Actions for commercial propertyowners & builders

• Install fully shielded exterior lightingfixtures in newly constructed buildings

• Replace old fixtures with fully shieldedexterior lighting

• Reduce light levels on store fronts and in

parking area• After business hours turn off signs and

parking area lights

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Advantages of reducing lightpollution

•  Reduce energy consumption andindirectly the use of fuel, CO2, SO2emission and other particles

• Protect the environment, reduce thedisturbance of natural habitats (animals,plants and ecological system)

• Avoid glare for aircrafts and ships

• Avoid disturbing neighbors• Facilitate astronomy• Preserve a dark sky

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Thank You!