First assignment of group n°045
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I. What is light pollution?
Light pollution is the night environment degradation by the emission of an artificial light which causes important impacts on the ecosystem and human health. There are 3 main perceptions of light pollution: -the halo of light - the bright light -the intrusive light
This idea of light pollution was introduced by North American astronauts then Europeans who were the first confronted to the fast nocturnal environment degradation. Now, light pollution is a hot button issue.
Why this problem is becoming more and more actual? The fear of the dark, the increase of lighting supply and the increasing demand of security are reasons which explain the hyper lighting. The actual lifestyle is the cause of the need of a permanent lighting. The energy is cheap and most people are not aware of the consequences of this lighting particularly on the environment.
The lighting systems are not enough effective. Indeed, often they do not focus the light on the area to be illuminated. There is therefore a significant loss of energy and the lighting quality is poor. Lighting becomes a problem since lighting devices are often not adapted.
Overkill of lighting systems involved in light pollution: either there are too many devices in a small perimeter or these devices are too powerful. Moreover, the lighting units in France far exceeds the recommendations.
Light pollution also comes from the use of the lighting systems. Often, the use of lighting is higher than the real needs. A large amount of energy is wasted and pollution is even more important.
Source : « La pollution lumineuse » from ANPCN
II. Where does this pollution comes from?
a) Electronic Advertising Boards and Commercial Centers:
Many of the large electronic sign boards in the cities and on highways are lit up by powerful lights that focus on the boards from below. Lights end up reflected upwards off the boards. Restaurants, discos, pubs, games and shops in the cities also use a lot of light to attract customers. Many of the lights they use are not directed to any particular place, making its dispersion more than intended.
b) Streetlights and car lights:
In some cities, hundreds of miles of powerful streetlights stay on all night. This, together with the vehicles that use the roads all contribute a lot to the light being directed above and to other unintended places. It has been estimated that about 35% to 50% of all light pollution is produced by roadway lighting
Reference: http://www.shaflik.com/documents/LIGHT%20POLLUTION%20TECHNICAL%20PAPER.pdf
c).Indoor light and light reflection
Light pollution is divided into three categories: white light pollution, pollution of artificial daylight and phototherapy. Strong sunlight, the city's glass walls, glazed walls, polished marble and a variety of coatings, such as decorative light reflected glittering white light, blinding eye-catching, this is called white light pollution; after nightfall, shopping malls, hotels on the advertising lights, neon lights sparkling, dazzling, even some strong beam into the sky, making the night as during the day, so-called "city that never sleeps," also called artificial daylight; discos, nightclubs installed black lights, rotating lights, fluorescent and flashing colored light source in this category is called light pollution.
The main causes of indoor light pollution can be summarized in three aspects:
(1) Interior decoration with mirror, glazed walls, polished marble and a variety of other decorative coatings reflect light, glittering white light, blinding eye-catching.
(2) Interior lighting configuration design unreasonable, resulting in indoor light is too bright or too dark. Nowadays, people understand there is a lighting design all kinds of errors that lighting design is a simple selection and arrangement of lamps.
(3) Outdoor lighting at night, disturbing light especially floodlighting buildings, and some are direct to people's eyes caused by glare, some irradiated through the window into the room, and the room is very bright shine, affect people's normal life.
Light reflection
Sunlight can be approximated as parallel light, when the parallel light beam is incident on the smooth surface, the specular reflection occurs, the reflected light is parallel light propagation parallel light in only one direction, in the direction of the light intensity is strong, looks very bright form a reflective glare glass curtain wall consists of a large piece of glass block, smooth surface glare of sunlight reflecting mirror formed by the human eye will be injected into people see things, hitting the indoor or outdoor environments it will make the ambient temperature rises.
III. What’s the impact to environment and ecosystem?
a) Waste of resources:
It costs a lot of money to light up homes, public places, sports and commercial places. Apart from the fact that tax payers pay needlessly for this, the nation uses millions of tons of oil and coal to produce the power needed to light the sky. Meanwhile, the environmental cost of producing this energy is another worrying issue that can be discussed at another time. In the USA, 8% of its total energy is used for outdoor lighting, and out of that, 80% is used for commercial and public exterior lighting.
b) Health implications:
Disability glare, eye strain, loss of vision and stress that people get from glare and spillovers are worth mentioning. Our eyes naturally adjust during day and night so we can see things properly. Too much light can harm our eyes and also the harm the hormones (such as melatonin) that does this job.
c) Wildlife:
Turtles many insects, birds, mammals and reptiles are photoperiodic in nature. Examples include sea turtles. Many aspects of their physiology and behaviour are influenced by day–night or circadian rhythms. This means their eating, mating, growth and development, movement and other activities are in relation to the balance of day and night. Artificial lights, even in small amounts can distort their natural operations and cycle. Thousands of deer and animals are killed on the roads by vehicles in the evenings, because the glare of these cars blind them and are unable to run off the streets before they are knocked down.
IV. What is collective light?
Collective light is the light produced by society, that is to say lights produced when people are home and they turn on the light at night to see in their houses, light produced by lamps in the streets to lighten them for people who are out at night, light on monuments or buildings, for example when people work late at night, the entire building is lighten, so collective light is artificial light created in order for people to be able to see at night. But some of that light is irrelevant, or miss-used. Indeed, people tend to want to light more than they need, because they are used to see clearly thanks to the light of day, and so there is an over lighting at night. For example, streets are lighten up all night long even when there is no one outside. Same, some monuments like churches, or work buildings are lighten up even say at 4am when no one is looking, or in it. Why do people always need so much light at night? Because life at night becomes more and more important, a lot of people are active by night and because electricity is easy to get, society over-uses light even when not needed. The accessibility to electricity and so light is what drove people to think that they could leave
lights on all the time, that it was not a big deal, because in general, people don't know about this problem that is light pollution.
V. What results do we want to achieve?
All of light which is bad for us or for the nature we call it light pollution . for the car , now more and more can use LED , but that cause the oncoming car barely see the road , why the car need light , that provides traffic accident . the light on the car is designed for leading the road in the night , not for bothering the oncoming car . As well as the street light , most of our outdoor lighting remains unshielded, sending light straight into the sky, into our eyes, into our neighbors’ bedrooms. They are designed for leading the road , not for disrupt sleeping and changing the environment for some species animals . So , we want light to light where they are supposed to light . we need the light concentrate . The relatively simple act of shielding our lights — installing or retrofitting lamp fixtures that direct light downward to its intended target — represents our best chance to control light pollution.
VI. Possible solutions
Some solutions are already existing, what are they and why are they operative?
Decrease intensity: make the eye able to adapt to the lighting and to keep the place safe.
Adjust the light beam: We don’t want to see the sky; we just want to see the road and the street.
Time control: Install movement detector or MINUTEUR, will reduce electricity bill and light on the lamp will reduce lighting pollution.
Reducing « blue light »: blue lights are more or less dangerous to our eyes. Furthermore it also hide stars in the sky.
Changing lamp bulb: Changing halogen by sodium lamp will light better and decrease exponentially the blue light.
After a phone call to the association ANPCEN (Association Nationale pour la Protection du Ciel et de l'Environnement Nocturnes) the major cause of the lighting pollution is collective lighting!
Source : « La pollution lumineuse » from ANPCN and « les solutions » from ricemm.org
Suggestion for implement
We can do lots of thing for feducing light pollution, such as reducing sky glow, reducing glare, reducing light trespass, and reducing clutter. The method for best reducing light
pollution, therefore, depends on exactly what the problem is in any given instance. Possible solutions include:
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, so that they direct their light more accurately towards where it is needed, and with fewer side effects.
Adjusting the type of lights used, so that the light waves emitted are those that are less likely to cause severe light pollution problems. Mercury, metal halide and above all first generation of blue-light LED road luminaires are much more pollutant than sodium lamps: Earth atmosphere scatters and transmits blue light better than yellow or red light. It is a common experience observing "glare" and "fog" around and below LED road luminaires as soon as air humidity increases, while orange sodium lamp luminaires are less prone to show this phenomenon.
Evaluating existing lighting plans, and re-designing some or all of the plans depending on whether existing light is actually needed.
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