It is usually spoken of Light pollution or photopollution when artificial lighting is so abundant and ubiquitous that it affects the normal and desirable darkness of the night. In this way, once night falls, many artificial light sources take over from the sun in urban centers and even in smaller towns.
Some scientists define the contamination light such as infrared, visible light radiation emitted to the exterior or to the exterior, and that due to its direction, intensity and quality, can have an uncomfortable harmful effect on man, on the landscape, or on ecosystems.
La contamination light It is a form of pollution that is little evoked because a priori it is not very harmful to health, when compared to the classic pollution of waste, urban smog, sewage, and so on.
However, the contamination light it has consequences on living beings and can be easily reduced.
Since 1830, those responsible for the lighting of Paris only lit one streetlight in two on nights with a clear moon. An operation related to the concern of saving and not so much with the contamination light, which was still very insignificant. More recently, the American Dark Sky Association, which since 1988 made this phenomenon known, which has been amplified to something genuinely harmful, and well visible by all. Indeed, the luminous points do not stop multiplying.
En 1992, the UNESCO It enshrined in its declaration on the rights for future generations, a specific section on the right to the conservation of the sky and its purity. In 2002, the Congress of Venice and Lucerne issued calls to world governments to safeguard the night sky. Currently, the ONU it intends to consider the starry sky as a common heritage of humanity.
Identify light pollution
La contamination light it is particularly visible when the sky is covered by low clouds, as these reflect and scatter light for miles. In this way, the sky appears dark orange-pink. This is particularly visible in large crowds. Normally, the sky should be completely black, or only illuminated by the moon. When the weather is clear, and out of town, the sky it is much blacker than in the city, and the presence of a large city can easily be identified by the change in the hue of the sky that turns pale pink and lights up.