Light Pollution

By Ajay pandey

MSc sem I(PSEVS104)

Department of Environmental Science

University of MUMBAI

KJ SOMAIYA COLLAGE OF

SCIENCE AND COMERCE

OCTOBER 2012

LINE OF PRESENTATION

• Introduction• Light pollution and types• Causes of light pollution• Effect of light pollution• Mitigation• Conclusion• References

Introduction

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 educational interest.

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?

• Sky glow• glare• Light Trespass• Over lighting

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 trespassLight 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.

Light Pollution is Trespass

glare

The condition of glare result when more than necessary illumination is applied to an area leading to several ill effects, including eye irritation.

Causes by high contrast between light and dark areas, glare can also make difficult for human eye to adjust to the difference in brightness

Light Pollution is Glare

Light clutter

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 roads ways.

causes

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

causes

• Over-illumination by artificial light stems from a number of factors, such as-

• Not using timers or occupancy sensors to put off light when needed.

• 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

Light Pollution is Overlighting

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 chronic fatigue

.

Effect fauna• 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 pollution intense.

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.

mitigation• 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.

conclusion

• 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.

references• Books• 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. 3rd Ed.

Delhi: Narosa• • Websites• Pollution Issues http://www.pollutionissues.co.uk/noiseandlight [accessed

20/8/2012]• Sources of light pollution http://www.nature.nps.gov/night/sources.cfm

[accessed 19/8/2012]• Pollution control http://www.dorsetforyou.com/384726 [accessed

20/8/2012]• Pollution http://www.curiosity.discovery.com/question/what-effect-

pollution-humans. [accessed 20/8/2012]• 5 ways u can reduce light pollution

http://www.mnn.com/yourhome/remodeling-design/stories/5-ways-you-can-reduce-lightpollution [accessed 19/8/2012]