Light pollution

Light pollution is one of the lesser-known forms of pollution. Even though it is not well known, it is still a problem and affects us and our environment in many ways. In collaboration with two friends from South Africa we have created a post that provides information on light pollution, including data from a self-conducted survey.

So, what is light pollution?

Light pollution is the pollution of our atmosphere through inappropriate or excessive use of artificial light.

About 80 % of the world’s population currently lives under light polluted skies. Under this link you can see a map showing how bad light pollution is in different parts of the world: light pollution map (

Light pollution can be divided into five categories, but in most cases, it is a mix of multiple categories:

  1. Over-illumination:
    Excessive use of light
  2. Glare:
    Excessive brightness causing visual discomfort
  3. Skyglow:
    Brightening of the night sky over inhabited areas
  4. Light trespass:
    Light falling where it is not needed or intended
  5. Clutter:
    Bright, confusing and excessive groupings of light sources

artificial = künstlich
Over-illumination = Überbelichtung
Glare = Blendung
Clutter = Unordnung/Ansammlung

Sources: [1] [2]

Light pollution around the world
(collaboration with South Africa)

In collaboration with our friends in South Africa we tried to find the differences in light pollution in different parts of the world.

We discovered that the main causes and effects of light pollution are pretty much the same in all areas affected by it. You can read more about the causes and effects of light pollution below.

Here are examples of night-sky-views and our estimation on where they are on the Bortle Scale:

Night sky in Melchsee-Frutt, Switzerland (on a full moon) | 2 on the Bortle Scale [a]
Night sky in Melchsee-Frutt, Switzerland (on a full moon) | 2 on the Bortle Scale [a]
Night sky in Borgo Vaslugana, Italy | 5 on the Bortle Scale [b]
Night sky in Borgo Vaslugana, Italy | 5 on the Bortle Scale [b]
Night sky in Gauteng, Johannesburg, South Africa | 6 on the Bortle Scale [c]
Night sky in Gauteng, Johannesburg, South Africa | 6 on the Bortle Scale [c]
Night sky in Le Lavandou, France | 8 on the Bortle Scale [d]
Night sky in Le Lavandou, France | 8 on the Bortle Scale [d]


We conducted a survey on light pollution to find out what other people think about it, know about it etc. A total of 53 people participated in the survey.

Our survey showed that only a few people have heard of light pollution before (Diagram 1: 75 % answered with a number below 5). Fortunately, a lot of people seem to be interested in learning more about light pollution (Diagram 2: 65 % answered with a number above 5), think it is important to reduce it (Diagram 3: 77 % answered with a number above 5) and are willing to do something about it.

A lot of people don’t really feel affected by light pollution. The most frequent answer to our question “How does light pollution affect you personally”, aside from “I don’t know” and “not at all”, was along the line of “My view of the night sky is impaired”. Other effects are barely noticed, even by people living under stongly polluted skies.

Suvey-results (pdf)


Main causes and effects

There are countless causes of light pollution, here are a few of the most important ones:

  • Poor planning of signage and streetlights
  • Irresponsible and excessive use of light
  • Overpopulation, because more people need more light
  • Smog and clouds, reflecting the light
  • Lights from cars and other motor vehicles

Just like there are many causes of light pollution, there are a lot of effects to it, including:

  • Health effects, e.g. increased stress levels, heightened risk of heart attacks, sleep issues
  • Global warming, because of the electricity used for the lighting
  • Waste of resources, because of the electricity used
  • Vision of night sky is impaired
  • Various negative effects on our ecosystem

environmental [3]


Not a lot of people are doing anything against light pollution yet – probably because a lot of them don’t know about the problem.
There are many possibilities to help reduce light pollution and that require very little effort. Here are some things everyone can do:

  • Reduce the use of decorative lighting
  • Use covered bulbs so that light faces downwards
  • Use LED lights instead of light bulbs
  • Minimize the use of light
  • Use automatic systems to turn off lights at certain times
  • Refrain from light trespassing
  • Use motion sensors on important outdoor light
  • Use warm, orange lights instead of cold, blue lights
  • Participate in a dark sky week or a similar event

Sources: [4][5]

Collaboration Team

Emma Elmiger (Switzerland)
Jasmin Lehmann (Switzerland)
Mono Wikner (South Africa)
Savanah Jackson (South Africa)


Livia Lehmann
Simona Crepaldi


[1] Light pollution (
[2] Light pollution (
[3] Causes and effects of light pollution (environmental
[4] Ways to reduce light pollution (
[5] (

header picture (pixaby)
[a] picture by Emma Elmiger
[b] picture by Leara Krohne
[c] picture by Mono Wikner
[d] picture by Michelle Zenger

On topic posts on dwme

The lighting conditions in the North


☷ See the project teams here »
☵ Some words about the contributions »

2 thoughts on “Light pollution

  1. I like the article and the whole topic of light pollution is new to me, so I have learned a lot of this article. I think also this is a concerning problem, it isn’t as bad as other ones like the actual earth pollution which we need to focus on more at the moment. There’s also electricity efficiency in the solutions for global warming included, so the problem of light pollution will automatically go away with the enforcement of those solutions.

  2. Light pollution is such an interesting and important topic! The light pollution map shows the situation perfectly and so do the pictures shown. I wish more people would know about this and then maybe they could help with the solutions you listed.

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