Light Pollution- Everything You Must Know (Download PDF)


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Light pollution is excessive, misdirected, or obtrusive artificial (usually outdoor) light. The rate of growth of this light is approximately two percent each year in both the amount of areas lit and the radiance of the light.

Image of Light Pollution

Image of Light Pollution

Image of Light Pollution

Above picture shows rates of change of the lit area of the world (left) and the measured brightness of each country during 2012 - 2016.

Use of LED Might Not Lead to Energy Savings, Why?

  • Both light pollution and energy consumption by lighting is steadily increasing over much of the planet challenging the assumption that increasing energy efficiency of outdoor lighting technologies lead to an overall decrease in global energy consumption.

  • Financial savings from the improved energy efficiency of outdoor lighting were invested into the deployment of more lights- this negating the large reductions in global energy consumption for outdoor lighting.

Effects of Light Pollution

Light pollution washes out starlight in the night sky interfering with astronomical research, other important effects include.

Disrupting Ecosystems

  • The rhythm of life is orchestrated by the natural diurnal patterns of light and dark; so disruption to these patterns affects the ecological dynamics.

    • Negative impact on plants and animals particularly nocturnal wildlife

    • Confuses migratory patterns of animals

    • Alters competitive interactions of animals

    • Change predator-prey relations

    • Causes physiological harm.

    Adverse Health Effects

  • Many species, especially humans, dependent on natural body cycles called circadian rhythms- production of melatonin regulated by light and dark.

  • Exposure to light while sleeping suppresses melatonin production leading to sleep disorders and other health problems such as increased headaches, worker fatigue, medically defined stress, obesity due to lack of sleep and increased anxiety.

  • Glare also causes aging of eyes.

  • Health effects are not only due to over-illumination or excessive exposure of light over time, but also improper spectral composition of light.

Energy Wastage

  • Lighting is responsible for one-fourth of all electricity consumption.

  • Over illumination constitutes energy wastage, especially upward directed lighting.

  • Energy wastage translates cost and carbon footprint.

Mitigation of Light Pollution

  • Shielding lights properly

  • Using light when and where it is needed

  • Using the amount of light that is needed

  • Using energy efficient bulbs

  • Using bulbs with appropriate spectral power distributions for the task at hand.

Which Images Were Analyzed?

Team, led by Dr. Christopher Kyba of the GFZ German Research Center for Geosciences in Potsdam, Germany, analyzed five years of images from the Suomi National Polar-orbiting Partnership satellite, operated jointly by the U. S. National Aeronautics and Space Administration and the National Oceanic and Atmospheric Administration.

Image of National Changes In Night Light Emissions

Image of National Changes In Night Light Emissions

Image of National Changes In Night Light Emissions

- Published/Last Modified on: December 10, 2017


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