One way to define light pollution is: light that hinders any of those five goals, plus wasted light and light that does harm. Glare = veiling or discomfort Uplight = light that shines upward Light trespass = light that shines where it isn’t needed or wanted Overlighting = too much light Inefficiency = using outdated technology
Cobra head streetlights Upward light from flag light -- much of the light misses its target
Glare from a pole light with poor shielding Can you see anyone in the playground beyond?
More glare Uplight --> You can see the top of the smokestack (5 storey or so tall)
By Ajay pandey
MSc sem I(PSEVS104)
Department of Environmental Science
University of MUMBAI
KJ SOMAIYA COLLAGE OF
SCIENCE AND COMERCE
LINE OF PRESENTATION
Light pollution and types
Causes of light pollution
Effect of light pollution
Light pollution also called photo pollution or
luminescence pollution refers to a brightening of night
sky due to scattering of artificial light by gaseous
molecule and dust particle in the air.
The scattering result in an orange foggy glow that
spread out over the horizon. it blights the night sky a
precious natural resource and an area of scientific and
light pollution is a consequences of poor engineering
practices that are both unnecessary and to a large
extent, avoidable its fallout is waste of money and
energy as well as degradation of the environment.
Light Pollution—What is it?
Types of light pollution
• Sky glow
Most of the times the lightning are not endowed
with adequate shielding provisions as a result the
light is reflected by the object it illuminates and spills
away into the sky.
In the atmosphere it is refracted causing orange
color sky glow sky glow refers to the glow effect that
can be seen over populated areas.
Light may go across property lines and
illuminates some one else premises. This
condition is called light trespass.
This is not only a nuisance but also a security
risk. A common light trespass problem occur
when a beam of light from one house enters a
window of another house.
This may lead to sleep deprivation or blocking
of a evening view.
The condition of glare result when more than
necessary illumination is applied to an area
leading to several ill effects, including eye
Causes by high contrast between light and
dark areas, glare can also make difficult for
human eye to adjust to the difference in
Refers to excessive groups of lights. Grouping
of light may generate confusion, distract from
obstacles and potentially cause accident
clutter is particularly noticeable as roads
where the street light are badly designed or
where brightly light advertising surrounds the
Light pollution is a side effect of industrialized
civilization it is cause due to excessive use of
arificial lights by humans.
the powerful artificial light, which are used to
illuminates offices, factories, sports stadium,
street, parks and sometime even housing
complexes obscure the night sky
Unlike the sunlight, the artificial light which are
thrust into the sky have many hues and colors
• Over-illumination by artificial light stems from a
number of factors, such as• Not using timers or occupancy sensors to put off light
• Not specifying the optimum level of light that is
desirable in particular premises.
• Improper architecture, especially of offices.
• Improper choice of fixture and bulbs which do not
direct light into the area that needed its most.
• Inadequate maintenance of lighting devices
Effect of light pollution
• Human health
Exposure to light at night suppresses the production of
hormone, melatonin. The latter is synthesized in the brain’s
pineal gland only when the eye signal it is dark.
Production begins around nightfall, peaks between 1-2 AM,
and shuts off during day. Hence melatonin is often referred to
as the hormonal expression of darkness.
Melatonin has several beneficial effect. It boosts the immune
system, lowers cholesterol. Protects the body’s cardiovascular
system, stabilize the biological rhythm and restore the night
cycle of rest and repair in its absence, a person suffer from
• Lightning from high-rise office buildings confuses migratory birds.
The avian crash into the buildings and die. In urban areas, wear
night lighting is very intense, sky scrappers injure or kill an
estimated 24000 birds each year.
• Artificial light along the sea beaches confuses baby turtle. It has
been observed that the turtles crawls instinctively to the brightest
visible objects- normally reflection of stars and moon
• The nocturnal frog are blinded by even dim light. Their ability to
hunt is drastically reduced.
• Outdoor lighting causes a significant decline in the population of
moth by exposing them to predators. It also disturb the flight,
vision, migration and feeding habits of moths.
• Pumas travelling at night avoid brightly lit areas. They lose their
track and miss crucial landscape linkage at places wear light
Effect on flora
• Light pollution around lakes prevent zoo plankton
like daphnia from consuming surface algae. This
causes the algae colonies to bloom. The lake
becomes stratified due to eutrophication.
• Night blooming flower depend on nocturnal
insect for pollination. However, light pollution
interferes with ability of these insect to navigate.
Therefore in intense light they lose their ability to
be potential pollinators. As a result species of
night flowering plant are register decline.
• 1. improved fixtures
The major contribution to sky glow comes from
street light. Therefore to curb light pollution, it is
essential to improve upon the design of fixtures. The
most commonly used fixtures for street lighting are
the drop lens cobra luminaire.
A flat lens cobra luminaire, on the other hand thrusts
the light exclusively downward such fixture are also
called full cut off fixtures. These not only curtail light
pollution, but prevent energy wastage too.
• Improved light sources
Different types of light sources are used under
different circumstances. Over the years, sodium
lamps have come to be regarded as best bargain for
street lights. These give good visibility to the
motorist even during foggy weather. Further, these
have low operational costs and remarkable efficiency
in terms of lumens per watt. Moreover, sodium
lamps give out light of narrow wavelength.
• Over the past 120 years- since the invention of
Edison’s bulb-human beings have deviated
from natures age old protections that are
afforded by rest and repair during sleep and
darkness. Just as we need daily exposure to
natural sunlight to reset our biological clocks,
we need ton sleep in total darkness to reset
our diurnal rhythm. Light during darkness is a
potentially serious threat, not only to human
being, but to other organism as well.
Roger A kirch(2005) At Days close: night in time past;
Catherine Rich(2006) Ecological consequences of Artificial Night Lightning
GS sodhi(2009) Fundamental concept of Environmental chemistry. 3 rd Ed.
Pollution Issues http://www.pollutionissues.co.uk/noiseandlight [accessed
Sources of light pollution http://www.nature.nps.gov/night/sources.cfm
Pollution control http://www.dorsetforyou.com/384726 [accessed
Pollution http://www.curiosity.discovery.com/question/what-effectpollution-humans. [accessed 20/8/2012]
5 ways u can reduce light pollution
http://www.mnn.com/yourhome/remodeling-design/stories/5-ways-youcan-reduce-lightpollution [accessed 19/8/2012]