The switch to outdoor LEDs has resulted in even more light pollution

Sunday, 26 Nov, 2017

This light pollution can have serious consequences for living things, which have evolved in accordance with a natural day-night cycle, where the only major sources of light at night would have been the moon or more intermittent sources such as volcanoes, lightning, wildfires or auroras.

Suburban sprawl in the United States and other developed countries is gobbling up once dark, quiet expanses of land, while explosive growth in China has been producing entirely new cities in what was once empty countryside. This whole study was based on the radiometer designed especially for nightlights, called the VIIRS (Visible/Infrared Imager Radiometer Suite).

The research team used the US's Suomi NPP satellite, which is jointly operated by NASA and the National Oceanic and Atmospheric Administration, to track and map night-time illumination on Earth for four years, recording which square miles remained in darkness and which were lit up.

Asia, Africa and South America, for the most part, saw a surge in artificial night lighting.

A team of global researchers has found that, despite an increase in energy-efficient LED bulbs, surface light pollution has increased around the world.

Declines in lighting were rare, but were noticeable in war-torn places like Syria and Yemen.

Light pollution is even worse than that, according to the German-led team, because the sensor used can not detect some of the LED lightings that are becoming more widespread, specifically blue light.

"This is concerning, of course", said Frank Holker of the Leibniz Institute of Freshwater Ecology and Inland Fisheries in Berlin, a co-author of the study. There is an overall increase in the total amount of light even if many cities are switching to LEDs and are going dark.

The American Medical Association past year said that white LED lights are increasingly suspected of impacting humans, estimating they have "five times greater impact on circadian sleep rhythms than conventional street lamps".

Scientists fear that this "rebound effect" might partially or totally cancel out the savings of individual lighting retrofit projects, and make skies over cities considerably brighter.

These observations probably understate the true increase because the satellites used in the study are not sensitive to blue light wavelengths emitted by LED lights.

The scientists concluded that light pollution was "on the rise" in some of the world's brightest nations, like the US, UK, Germany, Netherlands, Spain and Italy.

The latest findings are "not a big surprise to people who have been following this issue", said Travis Longcore, an assistant professor of architecture, spatial sciences, and biological sciences at the University of Southern California School of Architecture.

"It's not just a problem of the West. we're really seeing it all over the world", Barentine, who was not involved with the study, told CBC News.

"We are convinced that artificial light is an environmental pollutant with ecological and evolutionary implications for many organisms from bacteria to mammals, including us humans and may reshape entire social ecological systems".

But the researchers found that "as light gets cheaper, we use more of it, almost proportionately to the rate at which it's getting cheaper", Kyba says.

It also makes it harder for people to sleep by upsetting their body clocks.

"There is no conclusive evidence that additional light reduces crime", Longcore said. The persistent amount of light was emitted and new lights were being appended in other places.