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More than 80% of the world’s population lives
under light-polluted skies, a study suggests.
Scientists explain in Science Advances how
ground measurements and satellite data were
used to create an atlas of a world brightened by
artificial lights.
It reveals that the population of Singapore,
Kuwait and Qatar experience the brightest night
skies.
Conversely, people living in Chad, Central African
Republic and Madagascar are least affected by
light pollution.
Dr Christopher Kyba, from the German Research
Centre for Geosciences in Potsdam, said: “The
artificial light in our environment is coming from a
lot of different things.
“Street lights are a really important component,
but we also have lights from our windows in our
homes and businesses, from the headlights of our
cars and illuminated billboards.”
The brightness map reveals that 83% of the
world’s population, and 99% of Europeans and
people in the US, live under skies nearly 10%
brighter than their natural starry state.
For some though the artificial glow was even
greater, said Dr Kyba.
“About 14% of the world’s population don’t even
use their night-time vision,” he explained.
“The night is so bright that they use their colour
daytime vision to look up at the sky.”
In Singapore, the entire population lives under this
extreme level of artificial night-time brightness,
and it is a problem affecting many other parts of
the world.
“Twenty percent of the people in Europe and 37%
of the people in the US don’t use their night
vision,” said Dr Kyba. “It’s really an enormous
number.”
He added: “In the UK, 26% of people are using
colour vision and not night vision.”
The researchers warn that nights that never get
darker than twilight are affecting nocturnal
animals, while in humans, the trend has been
linked to sleep disorders and disease.
Dr Kyba said that while lighting was important for
development and safety, technology needed to
improve.
“There are a lot of street lights that are not
particularly well designed,” he explained.
“They shine light into areas that are not useful –
so up into the sky, for example, isn’t really useful
for anybody.
“There’s a big difference between having a well-lit
street, which means everybody can get around
really easily and safely, and a brightly lit street,
which could mean there’s too much light and it’s
not helping anyone.”
The paper suggests that lights that are shielded,
or can dim or turn off while not being used, could
help to reduce light pollution as well as save
energy.
The researchers add that light pollution is
hindering astronomy: a third of the world now
cannot see the Milky Way.

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