HKU Bulletin June 2013 (Vol. 14 No. 3)

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. À ± ã ¸ µ ² ¹ ° · ¹ ä à · ¹ á µ à » ¹ å æ ¯ « Ç © æ æ © ç Ú © Ù Õ © è ¤ £ ¾ Ü Ù ¤ Ú ¤ Û ¤ ¨ ¤ ¬ Ã ¤ Ù ¤ ¨ ¬ ¾ ¯ © ¾ ¯ ¯ é ¾ © ¤ £ ª 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