Light pollution is the presence of unwanted, inappropriate, or excessive artificial lighting. In a descriptive sense, the term light pollution refers to the effects of any poorly implemented lighting, during the day or night. Light pollution can be understood not only as a phenomenon resulting from a specific source or kind of pollution, but also as a contributor to the wider, collective impact of various sources of pollution.
Although this type of pollution can exist throughout the day, its effects are magnified during the night with the contrast of darkness. It has been estimated that 83 percent of the world's people live under light-polluted skies and that 23 percent of the world's land area is affected by skyglow.
The area affected by artificial illumination continues to increase.
A major side-effect of urbanization, light pollution is blamed for compromising health, disrupting ecosystems, and spoiling aesthetic environments. Globally, it has increased by at least 49% from 1992 to 2017.
Solutions to light pollution are often easy steps like adjusting light fixtures or using more appropriate lightbulbs. However, because it is a manmade phenomenon, addressing its impacts on humans and the wider ecological systems of Earth involves vast societal complexities that overlay light pollution with political, social, and economic considerations.
Light pollution is the presence of anthropogenic artificial light in otherwise dark conditions.
The term is most commonly used in relation to in the outdoor environment and surrounding, but is also used to refer to artificial light indoors. Adverse consequences are multiple; some of them may not be known yet. Light pollution competes with starlight in the night sky for urban residents, interferes with astronomical observatories, and, like any other form of pollution, disrupts ecosystems and has adverse health effects.
Light pollution is a side-effect of industrial civilization. Its sources include building exterior and interior lighting, advertising, outdoor area lighting (such as car parks), offices, factories, streetlights, and illuminated sporting venues.