2. What is Light Pollution?
• Light pollution, also known as
photopollution or luminous
pollution, is excessive or obtrusive
artificial light.
• Light pollution first made news in
1964, when an observatory was
specially placed just to avoid light
pollution
3. • Light pollution can be divided into two
main types: (1) annoying light that
intrudes on an otherwise natural or low-
light setting and (2) excessive light
(generally indoors) that leads to
discomfort and adverse health effects.
• It is most severe in highly industrialized,
densely populated areas of North
America, Europe, and Japan and in major
cities in the Middle East and North
Africa.
4.
5.
6. Types of Light Pollution
Light Trespass : occurs when
unwanted light enters one's property,
for instance, by shining over a
neighbor's fence.
Causes problems such as sleep
deprivation or the blocking of an
evening view.
7. Over-illumination : is the excessive use of
light.
Over-illumination is responsible for
approximately two million barrels of oil
per day in energy wasted.
8. Glare : is difficulty seeing in the presence of
bright light such as direct or reflected sunlight
or artificial light such as car headlamps at night.
Glare from
bad lighting is
a public-health
hazard—
especially the
older you
become.
9. Light Clutter : refers to excessive
groupings of lights. Groupings of lights
may generate confusion, distract from
obstacles and potentially cause accidents
10. Sky glow : refers to the "glow" effect that can be
seen over populated areas.
It is the combination of all light reflected from
what it has illuminated escaping up into the sky
and from all of the badly directed light in that
area that also escapes into the sky, being
scattered (redirected) by the atmosphere back
toward the ground.
11. Consequences
Effect on Human Health &
Psychology:
1. Increased headache incidence, worker
fatigue, medically defined stress,
2. Effect on mood and anxiety
3. Elevate blood pressure by about eight
points
4. Risk of breast cancer
12. Disruption of Eco Systems :
1. Poses a serious threat in particular to
nocturnal wildlife
2. Having negative impacts on plant and
animal physiology
3. It can confuse animal navigation
4. Change predator-prey relations
5. Light pollution around lakes prevents
zooplankton, from eating surface algae
6. Lights on tall structures can disorient
migrating birds
7. Sea turtles do not come to shore and
nest as often
8. Migrating fish species (salmon, herring,
etc.) cluster under artificial lights
causing unnatural concentration of fish
13. Effects on Astronomy :
1. Is very sensitive to light pollution
2. Reduces the contrast between stars and
galaxies
3. In densely populated areas sky
brightness as much as 100 times
brighter than is natural.
Energy Waste :
1. Lighting is responsible for one-fourth
of all electricity consumption
worldwide
2. Public lighting is the single largest
source of Greenhouse Gas Emissions
14. REDUCTION
☺Utilizing light sources of minimum
intensity necessary to accomplish the
light's purpose.
☺Turning lights off using a timer or
occupancy sensor or manually when not
needed.
☺Improving lighting fixtures by use of full
cutoff fixtures help to reduce sky glow by
preventing light from escaping above the
horizontal .
☺Adjusting the type of lights used, so that
the light waves emitted are those that are
less likely to cause severe light pollution
problems.
15. A flat-lens cobra luminaries,
which is a full-cutoff fixture,
is very effective in reducing
light pollution. It ensures that
light is only directed below the
horizontal, which means less
light is wasted through
directing it outwards and
This kind of LED
droplight could reduce
unnecessary light
pollution in building
interiors
