21 November 2014

Light pollution - easy solutions, difficult implementation

Moritz M writes:*

Can’t sleep? Feel depressed? Chances are that the reason might be in front of your window: more and more studies suggest that light pollution is causing many health problems, including sleep deprivation, depression and various forms of cancer. This light pollution map illustrates how bright your city/district looks from space. Although the topic remained relatively disregarded in the past, governments and municipalities more and more realize the impact of excessive use of light on the environment, health and public spending. Many examples show how light pollution can be limited with additional technology: Fully shielded streetlights stop light to shine anywhere else than where it is needed – the street. But if we look closer at the “success cases”, we see that no of them were realized on a broad national basis. Since these technological solutions are relatively expensive to implement everywhere in a country and usually only find support, if the impact is felt directly by the population, e.g. if the area is famous for its clear night sky and there are no tourists anymore, because the sky has become too bright to watch the stars.

Therefore we must come up with other, more “globalizable” solutions. We have to work with what we already have (which is a lot of lights) and simply reduce the usage. As one of the first, France has stepped forward with a national regulation of the usage of light in public areas. Since June 2013 these regulations have been in place and the government claims to save energy equivalent to 250.000 tons of carbon dioxide annually (this is about as much energy as 750.000 household use in France). While the effect seems quite big, the actual regulations are not as excessive as one might think:
  • Interior lights have to be turned off one hour after the last staff leaves the building
  • Exterior lighting that illuminates facades and window lightning have to be turned off by 1am and can be turned on one hour before sunset (more details)
So far the regulations have been very successful in the country and should encourage policy makers to move on to other sources of light overuse. We still see the bright illuminated advertisements everywhere, even in the middle of the night. Why not also shut them off during the late night and ask for a progressive tax on every consecutive hour of the night? Companies will think twice about the reach of their advertisement and whether that is justified by higher costs.

Bottom Line: The solutions are right there. Just make them look attractive.

* Please comment on these posts from my environmental economics students, to help them with unclear analysis, other perspectives, data sources, etc.


  1. Do fewer lights which illuminate sidewalks and bike trails increase the probability that a person will choose to drive a car over walking or bicycling?

  2. Interesting topic ! Two notes:

    1. You may want to be more specific about what your paper focuses on. Just as you mentioned, different countries has different policies, which determine the costs of the light pollution in respective countries. Also, does your paper focus on the illuminated ADs, or the street light or both?

    2. Add to the previous post, another side effect of having fewer light would be the increase in crime rate during the night. Actually, one of the purposes to have street light on in night time is to prevent crimes prom taking place in the dark environment. Whats the trade-off here?

  3. Light pollution is an interesting topic and I fully agree that awareness on the problem is lacking. However, I can't help but wonder if a good set of curtains will not just mitigate the health risks you have mentioned. Awareness of the problem in this sense could then lead to home-based solutions, rather than country wide policy implementations.

    Perhaps your main focus should be on the significant waste of energy, rather than health risks that are (seemingly) easily mitigated.

    (furthermore: how does the excessive use of indoor lighting - i.e. staying up long after sunset - and its effects relate to the negative effects associated with light pollution? Are we not exposing ourselves to these risks regardless of the prevalence of light pollution?)

  4. I like your topic!

    I really think you check out this link: https://www.studioroosegaarde.net/project/glowing-lines/

    I don't know if you heard about it, but it is a smart way of using light on highways. Maybe you can use it in your essay. Check it out!


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