Determination of light pollution

Determination of light pollution
Light pollution denotes the brightening of the night sky caused by artificial light sources. © Helmut J. Salzer/

Involved sectors

Tourism and leisure, Nature protection, Transport, Local population/citizens, Other: Districts and other local authorities

Affected habitats

Areas for settlements and transport


The term “light pollution” denotes the brightening of the night sky caused by artificial light sources whose light is dispersed into the atmosphere. This can have various effects: the growth cycle of plants, for example, may be influenced by an artificially brightened environment. The sensory organs of nocturnal animals are specially adapted to night-time conditions, which makes them particularly sensitive to artificial light. Animals therefore attempt to avoid sources of light, so a well-lit street can therefore constitute a major barrier and contribute to habitat fragmentation. A large proportion of light pollution comes from poorly constructed or poorly installed light sources and can be avoided without any negative impacts, e.g. on road safety. An audit of public lighting can help to identify problem areas and offer appropriate solutions.


Impact in particular on Small mammals, Big mammals, Amphibians, Birds, Insects
Ecological impact  
Reduction of fragmentation or creation of new valuable habitats Brightly lit roads and residential areas, but also ski slopes, natural and cultural monuments, and floodlights from nightclubs can have substantial barrier effects at night.
Improvement or preservation of habitats Bright lighting affects all nocturnal animals. Intensive lighting can also disturb the growth of plants. Reducing the intensity of lights can therefore help to improve their habitats.
Time of realisation for measure Immediate: Reducing light intensity creates positive effects immediately.
Impact scope Local (municipality): In sensitive areas, e.g. the migration routes of birds or bats, the measures taken locally to improve the lighting situation can have transregional significance.


Implementation period Months: Carrying out the audit can take a relatively long time, depending on the data. The proposed improvements will be implemented over the long term and will depend on the budget and decisions made.
Frequency Non-recurring: Measures should be followed by an evaluation of their success.

Economic and legal aspects

Costs Low (1'000-10'000 EUR): This type of audit will cost between €2,000 and 10,000, depending on the size of the municipality, the number of light sources, and the availability of data. Subsidies from the public purse may be available up to around 80% of the costs.
Socio-economic impacts High: After such an audit, It is estimated that municipalities can cut their energy costs by 20-40% through targeted investment.
Sources of financing Public: local, Public: regional, Public: national, Public: European

Further information

Evaluation Besides the positive impacts on nocturnal animals, the scheme also has positive effects on human health, not to forget the cost savings through better thought-out lighting.
Information Other: Comprehensive information on the issue of light pollution is available from the International Dark-Sky Association (en)
Contact France: e.g. ADEME (French Environment and Energy Management Agency) in France (fr, en)
Good Practice Light pollution/light smog audits, Isère, France
Diagnostic de la pollution lumineuse
Diagnostica dell’inquinamento luminoso

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