Light pollution now blocks the Milky Way galaxy in the night sky for nearly 80% of Americans and more than one-third of the world, according to a study and global atlas released Friday.
Overall, more than 99% of Americans live under light-polluted skies, and some spots in the USA may never again experience a true night thanks to the perpetual, artificial light.
The phenomenon isn't new: Lighting of homes, streets, highways and bustling cities across the nation grew dramatically after World War II, said Chris Elvidge, a scientist at the National Oceanic and Atmospheric Administration’s (NOAA) National Center for Environmental Information.
"In our urban centers, you’ve got multiple generations of people that could not go out and see the Milky Way, and it’s a shame that they can’t,” said Elvidge, co-author of the study published in the peer-reviewed journal Science Advances.
The night-time glow can persist for hundreds of miles, blocking or partially obscuring stars, constellations and galaxies for residents far from large urban areas.
“If you live near Death Valley National Park, you only have a few sources of light pollution luckily, but you are close enough to Las Vegas to have the brightness of your sky increased,” said Fabio Falchi, lead author of the study.
Scientists, in the most comprehensive global assessment of light pollution’s impact yet, used low-light imaging from a NASA/NOAA satellite and combined it with data collected from over 30,000 sky brightness monitors to map out levels of light pollution in a radius of about 120 miles from any given location.
Researchers found Singapore, Kuwait, South Korea, Canada and Spain experience some of the world’s worst light pollution. In the USA, the East Coast struggles with the nation's most obscured night sky.
Falchi, who works for the Light Pollution Science and Technology Institute in Italy, said he hopes the research and the atlas, a book independent of the study that further examines the issue, can raise awareness of the adverse impacts of light pollution that most people don't consider, such as the harm on the environment.
Ecological impacts range from the disruption of nocturnal animals’ natural behaviors to the alteration of birds’ migratory patterns, said Travis Longcore, a professor of architecture and spatial science at the University of Southern California who was not involved in the study.
Excess light pollution also affects humans' circadian rhythms by disrupting the repair and recovery that occurs during sleep and leading to issues such as depression, obesity and an increased risk of cancer, Longcore said.
Excess light pollution could be reduced by shielding or limiting the amount of artificial illumination. Installing new infrastructure that does not allow light to escape into the atmosphere would help alleviate the problem, Elvidge said.
Using LED lights with warmer color spectrums instead of blue ones could also decrease circadian disruption.
“The fact of the matter is we could dramatically reduce the intensity, and our eyes will adapt to it,” said Longcore. “The eye is an amazing thing.”
