Goodbye, darkness: Light pollution has increased 49% over past 25 years, study finds – USA TODAY

There are only a few places left in America with a pristine night sky

The bright city lights in the United States are impeding stargazers views of the night sky. Researchers broke down the light pollution by county and found there are not many places left to see a pristine night sky.

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Earth'snight sky really isn't as dark as it used to be.

In fact, according to a new study, global light pollution has increased by at least 49% over the past 25 years.

"The global spread of artificial light is eroding the natural night-time environment," said study lead author Alejandro Snchez de Miguel of the University of Exeter in the U.K.

"This study provides clear evidence not only of how bad light pollution has become as a global problem, but also that it is continuing to get worse, and probably at a faster and faster rate," he added, in a statement.

The study found increases in light pollution were most pronounced in Asia, South America, Oceania and Africa.

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It also details what it callsthe "hidden impact" of the transition to solid-state,light emitting diode (LED) technology.

LEDs emit more blue light than previous lamp technologies, the study said, but satellite sensors are "blind" to this blue light and so underestimate the level of light pollution. Correcting for this, the study authors say the actual increase in the power emitted by outdoor lighting, and thus of light pollution, may be as high as a whopping270%.

This is likely the case in Europe and North America, where satellites appear to be detecting a leveling off or even a decrease in light pollution.

"To take the U.K. as an example, if you ignore the effect of the switch to LEDs which has been extensive you get the false impression that light pollution has recently declined," said Snchez de Miguel. "However, correcting for this effect shows it has really increased, and potentially very markedly.

"Contrary to popular belief, the installation of 'broad white' LED streetlights, whilst potentially providing some energy savings, has increased light pollution and also the impacts on organisms such as moths," he said.

A study earlier this year, also from the University of Exeter, found that animals such as moths can be confused by artificial nighttime lights, which can affect their place in the food chain.

Many otherstudies have indicated that light pollution, from streetlights and other sources, can have major impacts on the natural environment. Such pollution is likely to have played a role in the massive declines of insect populations in some areas.

TheInternational Dark-Sky Association suggests the increased and widespread use of artificial light adversely affects the environment,ourhealth and safety, andenergy consumption.

"There is no clear scientific evidence that increased outdoor lighting deters crimes," according to the IDSA. In addition, research suggests that "artificial light at night can negatively affect human health, increasing risks for obesity, depression, sleep disorders, diabetes, breast cancer and more."

The purpose of the association, which was not affiliated with the study, is "to protect the night from light pollution," according to its website.

Ruskin Hartley, executive director of the association, said in a statement that the transition to LED lighting has contributed to the increase in light pollution.

"Without concerted action to reverse this trend, the impact on the natural environment will accelerate," Hartley said,"further exacerbating the biodiversity crisis, wasting energyand meaning a whole generation will grow up in perpetual twilight."

The study was published in the journal Remote Sensing.

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Goodbye, darkness: Light pollution has increased 49% over past 25 years, study finds - USA TODAY