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Light pollution, also known as photopollution or luminous pollution, is excessive, misdirected, or obtrusive artificial light. Pollution is the adding-of/added light itself, in analogy to added sound, carbon dioxide, etc. Adverse consequences are multiple; some of them may not be known yet. Scientific definitions thus include the following: *Degradation of photic habitat by artificial light. *Alteration of natural light levels in the outdoor environment owing to artificial light sources. *Light pollution is the alteration of light levels in the outdoor environment (from those present naturally) due to man-made sources of light. Indoor light pollution is such alteration of light levels in the indoor environment due to sources of light, which compromises human health.〔(Hollan, J: What is light pollution, and how do we quantify it? ). Darksky2008 conference paper, Vienna, August 2008. Updated April 2009.〕 *Light pollution is the introduction by humans, directly or indirectly, of artificial light into the environment.〔Marín, C. and Orlando, G. (eds.): (Starlight Reserves and World Heritage ). Starlight Initiative, IAC and the UNESCO World Heritage Centre. Fuerteventura, Spain, June 2009.〕 The first three of the above four scientific definitions describe the state of the environment. The fourth (and newest) one describes the process of polluting by light. Light pollution competes with starlight in the night sky for urban residents, interferes with astronomical observatories,〔(【引用サイトリンク】title=Light Pollution and Palomar Observatory )〕 and, like any other form of pollution, disrupts ecosystems and has adverse health effects. Light pollution can be divided into two main types: *Unpleasant light that intrudes on an otherwise natural or low-light setting *Excessive light (generally indoors) that leads to discomfort and adverse health effects Light pollution is a side effect of industrial civilization. Its sources include building exterior and interior lighting, advertising, commercial properties, offices, factories, streetlights, and illuminated sporting venues. 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 like Tehran and Cairo, but even relatively small amounts of light can be noticed and create problems. Since the early 1980s, a global dark-sky movement has emerged, with concerned people campaigning to reduce the amount of light pollution. The International Dark-Sky Association (IDA) is one non-profit advocacy group involved in this movement. ==Impact on energy usage== Energy conservation advocates contend that light pollution must be addressed by changing the habits of society, so that lighting is used more efficiently, with less waste and less creation of unwanted or unneeded illumination. Several industry groups also recognize light pollution as an important issue. For example, the Institution of Lighting Engineers in the United Kingdom provides its members with information about light pollution, the problems it causes, and how to reduce its impact.〔(Light Nuisance ). Institution of Light Engineers〕 Since not everyone is irritated by the same lighting sources, it is common for one person's light "pollution" to be light that is desirable for another. One example of this is found in advertising, when an advertiser wishes for particular lights to be bright and visible, even though others find them annoying. Other types of light pollution are more certain. For instance, light that ''accidentally'' crosses a property boundary and annoys a neighbor is generally wasted and pollutive light. Disputes are still common when deciding appropriate action, and differences in opinion over what light is considered reasonable, and who should be responsible, mean that negotiation must sometimes take place between parties. Where objective measurement is desired, light levels can be quantified by field measurement or mathematical modeling, with results typically displayed as an isophote map or light contour map. Authorities have also taken a variety of measures for dealing with light pollution, depending on the interests, beliefs and understandings of the society involved. Measures range from doing nothing at all, to implementing strict laws and regulations about how lights may be installed and used. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「light pollution」の詳細全文を読む スポンサード リンク
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