As more of us live in cities, the question of light pollution is becoming increasingly topical and important to address. There seem to be three main causes, and also two key solutions which we could take to lessen the problem.
The main cause is almost certainly the use of lighting for advertising in public spaces. For example, if we look at cities such as Tokyo or Moscow, almost all available surfaces are fitted with some form of light, often for announcements or commercial use. This huge expansion in illuminated advertising is partly a result of competitive pressures, and also due to the power of such advertising, with flashing lights, video and pictures. A secondary cause is the large number or street lamps and security lights used in cities, which are intended to reduce accidents and crime by removing shadow areas at night. Finally, high levels of night-time traffic also produce light pollution, as drivers use headlamps which shine into windows and gardens after dark.
Turning to possible remedies, it might be tempting for governments to ban or regulate electric advertising billboards, but in many cases (for example in New York or London) these signs are now a local symbol. It would also be difficult to reduce security and traffic lights, because these are needed to keep residents and travellers safe. I would rather see a government-backed programme of light protection for private homes, involving better insulation against outside light after dark. This would allow residents to rest in their homes without being disturbed by the lights in the streets outside. Additionally, a voluntary ‘dark day’ once per week, supported by business advertisers, in which all commercial lighting is reduced, would allow residents to experience a more natural level of darkness without jeopardizing their safety.
In summary, advertising and public lighting are the main factors behind this problem. Better light insulation, and occasional voluntary reductions in commercial lighting, would greatly help the residents to live more in peace with a brightly illuminated environment.