"The invisible damage also affects the flowers and leaves of plants," said Yang Gongxia, a consultant with the Illuminating Engineering Society of China. He has long been engaged in city lighting projects and lighting landscape planning. "The strong light can also harm the cities' old buildings."

Call for darkness

There is a scenic spot 900 meters above sea level in Anji County, Zhejiang Province, whose sky sees purely dark nights even during Spring Festival. Even electric torches here are covered with cloth to reduce light exposure.

It is not dark by accident, though. The place is the first national night-sky preservation area that was created by the Chinese Academy of Sciences' Shanghai Observatory and Zhejiang Province departments.

Natural nightlight is composed of the visible energy reaching Earth from distant stars and the glow produced by atmospheric photochemical processes.

In the ever-bright city of Shanghai, the city's background light is too bright to conduct astronomical observations. Shanghai Observatory staff completed surveys of almost all the mountainous areas in Zhejiang and Jiangsu provinces before finally choosing Anji County.

There is a set of international norms when establishing night-sky preservation areas. All the residents living near the area, especially those living within a radius of 3 km, are expected to protect the dark sky by avoiding light pollution. Street lamps are fitted with specially designed shades to focus the light on the ground and block it from going up. The preservation areas then offer an ideal place for astronomical observation. Since instituting the changes in Anji County, two professional astronomical observation rooms and one scientific observation station have been built.

A call for rules

Except for the artificial light at night, light pollution also includes the mass reflection of sunlight caused by the high buildings with glass walls at daytime.

One day in 2008, taxi driver Meng Linghui was driving in downtown Urumqi, Xinjiang Uygur Autonomous Region. Suddenly a strong beam of light blinded him. He put on the brakes quickly but could not avoid an accident. A tall glass-walled building reflected the light.

"Because there wasn't sufficient evidence to prove that the light beam caused the accident, I had to shoulder full responsibility for this," said Meng.

According to Rui Lihong, Chief Engineer of the Urumqi Environmental Protection Bureau, other departments have been taking note over the last several years of the problems caused by light pollution. But the Central Government still has not adopted any regulation on the matter. This puts the related departments in an awkward situation, Rui said.

Many provinces and municipalities in the meantime have introduced local laws and regulations, setting restrictions on the glass curtain walls of buildings. In some big cities such as Beijing and Shanghai, designers and architects are required to consider light pollution during the earliest phases of building planning.

Beijing received its first light pollution complaint in 1999. Thirty households in a Xicheng District apartment building couldn't stand the strong sunlight reflected by the glass walls of the buildings nearby. Due to the absence of relevant laws and regulations, the related bureaus could only meditate between them. In 2004, Shanghai opened the first trial in public on light pollution of residents against enterprises. Finally, the plaintiff Lu Yaodong won, but he still felt it was a pity that the court didn't support his call for public apology by the enterprise and the compensation of 1 yuan. "Light pollution has interrupted my life for more than two years. Can't I even get a sorry from them?" he said.

In recent years, the Ministry of Environmental Protection and other departments have received many complaints about light pollution all over the country. Experts are calling for legislation, regulation on light management. They regard the establishment of the implementation system as a mission of urgent importance.