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A (Dimming) City of Light

The views expressed are those of the author and are not necessarily those of Scientific American.

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The French are taking a stand against light pollution. Starting this summer, most non-residential buildings in the country will have to shut off their lights at night in order to “reduce the print of artificial lighting on the nocturnal environment.”

According to France’s environment minister, Delphine Batho, this shift will reduce total annual energy consumption by the equivalent of 750,000 households. But, the main motivation behind the new decree is public health. According to Ms. Batho’s statement, artificial light can cause “significant disruptions on ecosystems” by disturbing sleep and migration patterns.

National Geographic’s Verlyn Klinkenborg says that light pollution  is largely the result of bad lighting design that “washes out the darkness of night and radically alters the light levels—and light rhythms—to which many forms of life, including ourselves, have adapted. Wherever human light spills into the natural world, some aspect of life—migration, reproduction, feeding—is affected.” Today, the world’s bright lights can be seen from space, as shown in NASA’s famous night lights photos.

The new French law will combat light pollution by forcing lights in non-residential buildings to blink out within a hour of the last employee’s departure. Even shop window displays will go dark at 1 am.

Exceptions include lights for Christmas and other special occasions, as well as significant tourist attractions. For example, the Eiffel Tower will continue to dazzle tourists with its hourly sparkles. And, Paris’s largest Christmas market, on the Champs-Elysees, will still be a lighted beacon to welcome in the holiday season.

Photo Credit:

1. Photo of night lights by NASA

2. All other photos by Melissa C. Lott. No reproductions or use permitted without Melissa C. Lott’s expressed permission.

Melissa C. Lott About the Author: An engineer and researcher who works at the intersection of energy, environment, technology, and policy. Follow on Twitter @mclott.

The views expressed are those of the author and are not necessarily those of Scientific American.

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  1. 1. abbihuggins 7:50 pm 02/12/2013

    I completely agree with the views of the author of this blog. More cities worldwide should take the initiative to reduce light pollution by turning out the lights at night. As humans we should be aware of the impact that we have on our environment.

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  2. 2. darklight_413 6:53 pm 02/14/2013

    I am a lighting designer with my own lighting design firm and I agree with Paris’s decision. However, there are ways to meliorate light pollution rather than mandating that everyone turn off their lights at night. Proximity and occupancy sensors, timers, and full cut-off fixtures are just a few ways to help. Legislation on light trespass rather than mandating turning lights off completely would be a better solution as well. This just sets it up for a backlash in my opinion.

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