Bulletin June 2013 (Vol. 14 No. 3) - page 22-23

Research
light coming from the nearby housing estates,
streetlamps and public lighting.
Dr Jason Pun Chun-shing of the Department
of Physics conducted the research, which was
widely reported in the local press. His findings
have prompted him to ask why, at a time when
the global trend is to take steps to conserve
energy and reduce pollution, is Hong Kong still
lit up so excessively.
“A decade ago when I started the study many
people were saying we’re the Pearl of the
Orient and we should be bright,” says Dr Pun.
“But, is this the only way to show that we are
a prosperous city?”
Asked to comment on the Symphony of Lights,
which nightly shines across the harbour as
a tourist attraction, Dr Pun says: “From our
data there is no strong evidence that it causes
prolonged light pollution – but it certainly
sends a particular kind of message to the
public and to tourists.”
But it is not the inner city that is Dr Pun’s main
concern: “Why are our outer urban areas so
brightly lit? As far as we can tell, our city’s
suburbs are as bright as or even brighter than
other city centres.” He then clarifies that
research elsewhere is not as comprehensive as
his in Hong Kong. “It’s a relatively new field,
we’re first to do this kind of systematic study
Paris may delight in being known as the ‘City
of Lights’, but a less romantic yet more apt
name for Hong Kong might be the ‘City of
Too Many Lights’. According to the results of
data collected by HKU’s Night Sky Brightness
Monitoring Network, at night our inner city
appears to have the worst light pollution on
the planet – more than a thousand times
brighter than the natural dark sky.
The highest figures, at more than 1,200
times brighter than a night sky without light
pollution, were recorded on the Tsim Sha Tsui
waterfront, and even in rural areas such as
the Wetland Park in Tin Shui Wai levels are
130 times the standard, most likely due to
on this scale. But I have seen initial findings of
other studies and as far as I recall I did not see
anywhere as bad as Hong Kong.”
Star-gazers worried
Dr Pun first became interested in light pollution
because of his background in astronomy.
“Star-gazers are the first to notice when
visibility lessens!” he says. “Myself and other
local astronomers saw the situation here
was worsening and were very worried about
proposals for more land developments –
particularly in eastern Sai Kung and southern
Lantau – two of the last remaining pristine
places for star-gazing.”
“We should protect our night sky,” he continues.
“Every civilisation on Earth has studied it, every
culture has stories based on the night sky. It
is fundamental to our thought – the eternal
question, what is our place in the universe?”
In addition to the star-gazing factor, light
pollution – which is the reflection in the sky of
city lights – is a problem for several reasons:
numerous studies of nocturnal animals show
ecological damage, and some recent research
has shown that increased exposure to night
light has a direct negative impact on human
health.
“There is indirect damage too,” says Dr Pun,
“simply from the waste of energy. If you’re
shining lights into the sky you’re wasting
energy because the light should reach your
eyes, not the sky.”
Dr Pun and his team have been studying light
pollution for 10 years, initially using traditional
astronomical instruments such as telescopes,
then using Sky Quality Meters (SQMs), a device
about the size of a pack of playing cards
capable of taking very accurate measurement.
They were highly portable, enabling the team
to take their research off-campus for the
first time in 2007 and embark on city-wide
research, then funded by the Environment
Conservation Fund (ECF). “We had 40 SQMs
and used teams of volunteers. In 2009 we
completed 2,000 readings,” says Dr Pun.
The big change in technology came in 2010
when SQMs became computer-controlled,
and Dr Pun and his team developed their own
interfaces to make the devices work through
wireless internet. “It enabled us to set up
18 measuring stations across Hong Kong, in
both rural and urban locations – we were the
first team in the world to do such a big-scale
project.”
From dusk ‘til dawn
“The meters take measurements once every
minute, basically from dusk ‘til dawn – in the
past three years they have taken more than five
million readings.”
The Physics Department team are now applying
for funding to expand the study to look
more closely at the exact source of pollution
and to determine long-term trends. “So far
we have built up a huge database and are
now completing publication, the next step is
collaboration with overseas institutions on an
international archive.”
Knowledge Exchange funding in 2012 has also
enabled Dr Pun to raise public awareness about
light pollution. “For Earth Hour this year, we
did a Science Roadshow on the harbourfront
in Tsim Sha Tsui during which we measured the
night sky changes,” says Dr Pun. “Brightness
levels reduced by two-thirds when the lights
went off, and suddenly you could see stars. It
was a dramatic demonstration of what we’re
missing.”
M
Brightness levels reduced by two-thirds when the lights went off, and
suddenly you could see stars. It was a dramatic demonstration of what
we’re missing.
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The Dark Side of Light
Tsim Sha Tsui’s night sky is more than a thousand times brighter than
a normal dark sky – making our light pollution probably the worst on
the planet. Dr Jason Pun thinks it’s time Hong Kong saw the light.
23
The University of Hong Kong Bulletin
June 2013
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