What are the sources of light pollution?
The scattering of artificial light by aerosols in the air causes light pollution, or sky glow, eg water droplets and fine particles. This type of pollution increased dramatically during the second half of the 20th century, and England is more brightly lit than any other European country, with the exception of the Netherlands. It also includes the intrusion of direct light eg a bright street light outside a bedroom window. The major sources of artificial light include: • Street lighting (in an urban environment about 40%) • Domestic and industrial security lamps (due to rising crime levels and fears over security, more and more homeowners are installing security lighting to domestic properties) • Advertising and display lighting • Floodlights for sporting events and building illumination. Sky glow is caused by poorly designed or installed light fittings, which allow a significant proportion of the light to be emitted above the horizontal. Some artificial light is also reflected upwards
