Hong Kong's light pollution is blindingly high, with brightness levels in Tsim Sha Tsui reaching 1,200 times higher than internationally accepted levels.
That's the dark message from the University of Hong Kong's Night Sky Brightness Monitoring Network, which says average brightness in the SAR between 8.30pm and 11pm is 100 to 1,000 times the international standard.
"The brightness is equal to 100 lampposts directing their light to a single point," network principal investigator Jason Pun Chun-shing said.
The findings were released yesterday in time for the World Wildlife Federation's Earth Hour event on Saturday when the public are asked to turn off their lights between 8.30pm and 9.30pm.
The monitor to measure brightness in Tsim Sha Tsui was installed above the Space Museum, close to the Hong Kong Cultural Centre and the Peninsula Hotel.
Due to limited space to set up equipment, the network could not collect the brightness data at Causeway Bay, Central and Wan Chai.
Pun said the skies suddenly get darker at 11pm, 12am and 1am every night.
"It appears that our lights are not limited to safety and security purposes," he said, adding: "Lights should be lit up for people and not for the skies."
The university's physics department measured the night sky brightness at 18 locations from May 2010 to March this year amid the growing awareness of light pollution.
Skies are 660 times brighter above King's Park in Ho Man Tin and 440 times brighter above Wong Tai Sin compared with standards set by the International Astronomical Union.
The measurements refer to the brightness of a night sky not under the influence of artificial light.
The network recorded that even the sky above the Wetland Park in Tin Shui Wai is more than 100 times brighter than the standard.
"It is due to brightness generated by the nearby developed areas including residential buildings in Tin Shui Wai as well as Shenzhen," Pun said.
The Astropark in Sai Kung is at least 20 times brighter than the international dark-sky standard before 11pm, even though it is the darkest station in the study.
"Light pollution is swiftly destroying the few remaining star- gazing locations in Hong Kong," Pun said. He urged the government to regulate outdoor lighting for commercial use at night.
In another development, Environment Secretary Wong Kam-sing said the Environment Bureau has set up committees to study light pollution and will announce results in a few months. "Many people believe regulations on light usages will affect our vibrant and dazzling culture, but times have changed," Wong said. "Some unnecessary lighting could be switched off to reduce nuisance and save electricity."