Light-pollution: an often forgotten side-effect of our industrialized civilization

Even pristine landscapes around urbanized areas are affected

Even pristine landscapes around urbanized areas are affected

A new and very extensive study on light pollution titled “The new world atlas of artificial night sky brightness” was published recently by a group of scientists from Italy, Germany, USA and Israel. The results were presented via detailed maps of artificial sky luminance, with the help of high-resolution satellite data, light pollution propagation software and new precision sky brightness measurements.

World map of artificial sky brightness. The map shows, in twofold increasing steps, the artificial sky brightness as a ratio to the natural sky brightness (assumed to be 174 μcd/m2). Fabio Falchi et al., 2016

Even though light pollution has received relatively little attention from environmental scientists in the past, it is considered to be one of the most pervasive forms of environmental alteration. It is also impressive that it can be observed hundreds of kilometers from its source (for example the light domes of Las Vegas and Los Angeles can be seen from the Death Valley National Park). However, apart from global ecological consequences, light pollution poses health issues, may even have an impact on human culture and of course wastes energy and money.

The charts below depict the 40 countries whose population is the most and least affected by the artificial sky brightness. The most light-polluted country is Singapore, where the entire population lives under skies so bright that the eye cannot fully dark-adapt to night vision. Other populations experiencing this level of light pollution are Kuwait (98%), Qatar (97%), United Arab Emirates (93%), Saudi Arabia (83%), South Korea (66%), Israel (61%), Argentina (58%), Libya (53%), and Trinidad and Tobago (50%); all of these countries have more than half of their inhabitants living under extremely bright skies.

Countries whose populations are exposed to the least light pollution. Color ranges are shown on the right and indicate the pollution level (μcd/m2). Fabio Falchi et al., 2016

Countries whose populations are most exposed to light pollution. Color ranges are shown on the right and indicate the pollution level (μcd/m2). Fabio Falchi et al., 2016

The overall statistics

More than 80% of the world and more than 99% of the U.S. and European populations live under light-polluted skies. The Milky Way is hidden from more than one-third of humanity, including 60% of Europeans and nearly 80% of North Americans

Action to be taken

Some of the measures to be taken in order to lower light pollution: the full shielding of lights (not allowing luminaires to directly send any light at and above the horizon or outside the area to be lit), the use of the minimum light for the task, turning off lights when they are not needed, reducing the total installed flux and the limitation of the “blue” light that interferes with circadian rhythms and scotopic vision.