The clock says 7pm but it's hard to tell if it's night or day in many parts of the city. A combination of neon signs, dazzling store windows and floodlit billboards, each brighter than the next, mask the twilight hours. The night's so bright these days you almost have to wear shades.
But while they make for pretty travel posters, the overpowering batteries of lights also put a blight on the lives of many people such as Mary Wong Sai-yung. The Fa Yuen Street resident lives opposite the
Hoi King shopping arcade, where billboards are lit by five spotlights so powerful that even heavy curtains can't keep out the glare.
'I find it hard to sleep. My bedroom gets really stuffy since I can't open the windows,' says the 42-year-old nurse. 'The lights are on till 5am although there are few pedestrians on the street after midnight.'
In Causeway Bay, stockbroker Julie Fong Man-lai shares a similar problem. Floodlights at an optical store across from her building on Lee Garden Street bathe her bedroom in a constant glow at night. 'It really bothered me when I worked an early morning shift because I had to be in bed early and couldn't sleep,' she says. That's no longer a problem now that she's on a later shift, but Fong still thinks it's a waste of electricity.
Are such complaints the gripes of an overly demanding populace? An inspection of fixtures in Causeway Bay and Mong Kok with electronic engineer Henry Chung Shu-hung one evening reveals what people have to put up with.
Perhaps the most extreme example is found at Windsor House, where some 60 floodlights illuminate four billboards on the side of the building. Using a meter to determine the lux, a measure of light intensity, Chung found that this translates to street level illumination of 9,000 lux.
That's almost as bright as being outdoors on a clear day - about 10,000 lux, says Chung, an associate dean of science and engineering at City University. And it's 18 times the light intensity recorded at the Victoria Park tennis courts - 500 lux - where floodlights are positioned to ensure visibility of a whizzing ball.
A spokesman for Chinese Estates Holdings, which manages Windsor House, says existing floodlights are needed for building renovations and the level will be reviewed when planning for permanent lighting.
Hysan Development, which has a brightly lit construction site billboard on Lee Garden Road, says the lights were installed for safety.
Emerging from Yau Ma Tei MTR station, Bank Centre on bustling Sai Yeung Choi Street catches the eye as another example of lighting overkill. The glare from its lights raises the intensity to about 4,000 lux - almost three times as bright as the recommended level when doing detailed drawings and other work requiring fine attention. A nearby newsstand has followed suit, installing metal halide lamps that cast radiance of more than 2,000 lux on the surroundings.
According to the Environmental Protection Department (EPD), the government acts to ensure that facilities such as advertising light boxes are 'structurally safe; will not become a serious risk of fire; will not interfere with road, marine and aviation traffic; will not disfigure the natural beauty of any scenery or affect injuriously the amenities of any locality'.
But people whose lives are disrupted by over-illumination have no course for redress because brightness levels are not regulated. Wong and her neighbours have complained to government departments and the management of Hoi King, to little avail.
Last year an internet campaign run by environmental group Green Sense drew 77 complaints about wasteful and annoying lighting, including floodlights that are kept switched on during the day, empty offices that are lit all night and construction sites that remain ablaze when work has stopped.
The group sent complaint letters to building and shop owners after checking lux levels at the sites, but few took action. The minority that responded were residential managers concerned that occupants were affected.
Environment affairs manager for Friends of the Earth, Hahn Chu Hon-keung, says Hong Kong has become much more ostentatious in its lighting since 1998 when restrictions were lifted following the closure of Kai Tak airport. That eased during the post-Sars downturn when people were trying to cut costs, but he says the respite was brief.
While much of the world strives to save energy and reduce use of fossil fuels to curb the effects of global warming, Hong Kong is blithely powering on. Electricity consumption for lighting rose 15.6 per cent between 1997 and 2005 - yet the population grew by just 4.9 per cent.
Our profligacy with lighting feeds into a harmful spiral from the so-called heat-island effect, says Edward Ng Yan-yung, a professor of architecture at the Chinese University. Heat from millions of bulbs raises the air temperature, prompting people to turn up their air conditioners, which in turn pump more heat into the environment even as they cool the interiors of buildings. Meanwhile, more fuel is burned to supply power for lighting and cooling, increasing carbon emissions and air pollution.
But because the eye is drawn to the brightest objects, advertisers and shops will compete to be the brightest on their street unless rules are introduced to curb wastage, says Chu. 'Some cities have introduced rules on lighting. But even if [regulation] is not common, we have a unique situation in Hong Kong where residential and commercial areas may not be separate.'
Light pollution takes a toll on health: studies in the US have found that it can increase stress and hypertension, aggravating cardiovascular disease. Over-illumination at night disrupts the production of melatonin and can aggravate heart problems. Several published studies also suggest a link between extended exposure to light at night and increased risk of oestrogen-related problems such as breast cancer in women.
Lighting complaints to the EPD have risen steadily from 33 in 2005 to 40 last year. Friends of the Earth will soon release a book of cases studies detailing the plight of residents adversely affected by living in brightness. Chu says he's dealt with more than 10 cases in the past year, including an elderly woman in Mong Kok who has not been able to sleep in her bedroom for months because of the glare from a sign outside. 'Instead, she's forced to sleep on a sofa in her living room.' In another example, three flat owners got tired of battling the shopping centre opposite their building and moved out.
People must come forward to complain about light pollution in order to push for regulation to control over-illumination, Chu says. 'When we talk of sustainable development, we must think about the social [impact] as well.'
Intrusive lighting is testing the public's tolerance. In a survey in Mong Kok of pedestrians' views on lighting conditions last year, Green Sense found that 87 per cent of 485 people polled believed there were excessive spotlights on billboards, 84 per cent thought it was a waste of electricity and 71 per cent said the light and heat made them uncomfortable. Most people (77 per cent) felt the government had failed to control outdoor lighting.
Detractors tend to dismiss green groups' proposals as calling for a virtual blackout, but activists insist what they're fighting is unnecessary and intrusive installations, such as flashing signs and spotlights whose glare is reflected into homes, and wasteful practices such as leaving lights on all night in empty offices.
'We need to show that it will not jeopardise business or living standards if some lighting is turned off,' Chu says. 'Hong Kong is a high-consumption, high-wastage and high-pollution city. Lighting is a good platform for people to rethink our lifestyle.'