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Light Pollution

by Deepak Subedi | 10-01-2019 13:37 recommendations 0

What is Light Pollution?

Light pollution is excessive, misdirected, or obtrusive artificial (usually outdoor) light. Too much light pollution has consequences: it washes out starlight in the night sky, interferes with astronomical research, disrupts ecosystems, has adverse health effects and wastes energy.



A little more than 100 years ago, you could walk outside at night even in a city and see the Milky Way galaxy arch across the night sky. Being able to see thousands of stars was part of everyday life, inspiring artists like Van Gogh or musical composers like Holst or writers like Shakespeare. By allowing artificial lights to wash out our starry night skies, we are losing touch with our cultural heritage (e.g., what has made us who we are). We are also losing touch with what could inspire future generations.

With more than half of the world’s population now living in cities, 3 out of every 4 people in cities have never experienced the wonderment of pristinely dark skies. How do you explain the importance of what they’ve lost to light pollution? How can you make them aware that light pollution is a concern on many fronts: safety, energy conservation, cost, health and effects on wildlife, as well as our ability to view the stars? Finally, how do you convince them that it’s worthwhile to take even small steps, to help fix this problem.


Fig:World map of artificial sky brightness. Image from the new “World Atlas of Artificial Night Sky Brightness.”

Effects of Light Pollution

In disrupting ecosystems, light pollution poses a serious threat in particular to nocturnal wildlife, having negative impacts on plant and animal physiology. It can confuse the migratory patterns of animals, alter competitive interactions of animals, change predator-prey relations, and cause physiological harm. The rhythm of life is orchestrated by the natural diurnal patterns of light and dark; so disruption to these patterns impacts the ecological dynamics.

With respect to adverse health effects, many species, especially humans, are dependent on natural body cycles called circadian rhythms and the production of melatonin, which are regulated by light and dark (e.g., day and night). If humans are exposed to light while sleeping, melatonin production can be suppressed. This can lead to sleep disorders and other health problems such as increased headaches, worker fatigue, medically defined stress, some forms of obesity due to lack of sleep and increased anxiety. And ties are being found to a couple of types of cancer. There are also effects of glare on aging eyes. (See text below.) Health effects are not only due to over-illumination or excessive exposure of light over time, but also improper spectral composition of light (e.g., certain colors of light).

With respect to energy wastage, lighting is responsible for at least one-fourth of all electricity consumption worldwide. Over illumination can constitute energy wastage, especially upward directed lighting at night. Energy wastage is also a waste in cost and carbon footprint.

The good news is that light pollution can be reduced fairly easily by shielding lights properly, by only using light when and where it is needed, by only using the amount that is needed, by using energy efficient bulbs, and by using bulbs with appropriate spectral power distributions for the task at hand.

Three Main Types of Light Pollution

Three main types of light pollution include glare, light trespass and sky glow (in addition to over-illumination and clutter). Glare from unshielded lighting is a public-health hazard—especially the older you become.

Glare light scattering in the eye causes loss of contrast, sometimes blinds you temporarily and leads to unsafe driving conditions for instance. 

Light trespass occurs when unwanted light enters one’s property, for example, by shining unwanted light into a bedroom window of a person trying to sleep. Sky glow refers to the glow effect that can be seen over populated areas. Sky glow is the combination of all the reflected light and upward-directed (unshielded) light escaping up into the sky (and for the most part, unused). Shielding lights significantly reduces all three of these types of light pollution.




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  • Dormant user Deepak Subedi
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  • Hema Sapkota says :
    Greetings Deepak
    I hope you are doing well!
    Thank you so much for this report!
    Keep writing
    Green cheers
    Posted 22-03-2020 11:02

  • Basanta Adhikari says :
    Greetings deepak
    I hope you are doing well

    Thank you so much for this report.
    I hope to read more from you.
    Keep up with great works
    Green cheers
    Posted 16-03-2020 04:11

  • Deepak Subedi says :
    Joon Ho Mentor, Namaste
    Yes mentor, many countries do not have access to electricity many are using whole night and making light pollution,
    Yes this is problem of city and town, we must know how light can affect us, we must reduce the use of excessive light.
    Thank You for your comment.
    Posted 15-01-2019 19:30

  • Joon Ho Mentor says :
    Hello Deepak, light pollution also arouses equality issue : poor cities or regions do lack light provision and how do rich regions or highly-populated cities can waste electricity to light up for a whole day and night. To add up, it is one of the modern society's problems as light was not that existent or easy to produce just about 100 years ago. But nowadays we are obviously wasting energy, especially produced by fossil fuel and then letting it go like it never existed there.
    Thanks for your light pollution report, and we have to think about this as other countries and regions will soon face this problem when they get developed in recent future, too.
    Posted 14-01-2019 22:31

  • Deepak Subedi says :
    Gyeongrin mentor
    Hope you are healthy and happy there
    Yes Mentor,light is one of the great invention of all time but due to excessive use, we are facing problems,so we must be aware about this topic and its solution
    Thank you for your comment.

    Posted 14-01-2019 20:38

  • Gyeongrin mentor says :
    Hello Deepak
    As light interferes our biorhythm, it is important that we have control over the exposure of light in our daily lives. However, as your report points out, nowadays streets are full of lights even in the night time, causing discomfort to some who live within.
    Light has been one of the greatest inventions that brought much comfort to human, however as everything has its own balance, now it seems that now we need to reduce and control some of the current usages.
    Thanks for the report :)
    Posted 14-01-2019 00:30

  • Deepak Subedi says :
    Hello Kushal Bhai
    I hope you are fine
    Yes,this is new type of pollution, due to excessive light in cities, we can reduce iit by proper use of light,
    You are welcome
    Thank You for your comments :)

    Posted 11-01-2019 19:42

  • Deepak Subedi says :
    Hello Rosa
    Hope you are fine and healthy
    Yes i was also unaware about light pollution, i read a article about light pollution and then read more about light pollution,
    now i am aware of this type of pollution,
    I hope you also learned somethings,
    Thank you for your comments :)

    Posted 11-01-2019 19:38

  • Deepak Subedi says :
    Hello Israel
    I hope you are well and fine
    Yes it is very important that light is part of our life,
    Thank You so much for your comment.

    Posted 11-01-2019 19:29

Kushal Naharki

  • Kushal Naharki says :
    Although there are other pollution which are much harmful to human beings and ecosystem like land pollution, air pollution and water pollution but effect of light pollution cannot be ignored. i feel like this pollution is new as it has increased due to increasing urbanization.

    If we don't take into account the effects caused by light pollution, it may also turned out to be huge problem in near future. Thank you Deepak dai for bringing us new topic into discussion.

    Thank you for the report dai. Keep writing great reports):)
    Green Cheers :) :)
    Posted 11-01-2019 01:57

  • Rosa Domingos says :
    Hey Deepak!

    I was not aware that light pollution was this distructive! Humans have really found a manner to which we have discouraged any form of looking at the sky and see all the stars that out previous generations had the privilege to see.

    Nevertheless, with continued awareness the negetive effects of pollution will diminish over time.

    Thank you for reporting Deepak!
    Posted 10-01-2019 20:14

  • Israel Adeoye says :

    You have actually touched a very sensitive issue. From the report, I can deduct that the cause of these pollution is its misuse by humans. However, that does not dispute the importance of lights and lighting to humans.

    Thanks for the report. It is really educating.
    Posted 10-01-2019 18:29

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