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Abstract

The US National Park Service (NPS) Night Skies Program measured changes in sky brightness resulting from a countywide lighting retrofit project. The retrofit took place in Chelan County, a gateway community to North Cascades National Park and Lake Chelan National Recreation Area in Washington State. The county retrofitted all 3693 county-owned high pressure sodium (HPS) street lamps to full cutoff LEDs. This number is about 60% of the County’s total outdoor street and area lights. About 80% of the newly installed lights were 3000 K in color temperature and 20% were 4000 K. The 4000 K LEDs were used to meet Washington State Department of Transportation guidelines. To measure sky brightness, we used the NPS night sky camera system before the retrofit started in 2018 and after its completion in 2019. These images were photometrically calibrated and mosaicked together to provide hemispherical images in V band. For comparison with our ground-based measurement, we obtained the satellite imagery taken by Visible Infrared Imaging Radiometer Suite (VIIRS) onboard the Suomi National Polar-orbiting Partnership satellite. Our measurements show that the post-retrofit skyglow became brighter and extended higher in the sky, but upward radiance, as measured by the day-night band radiometer, decreased. These divergent results are likely explained by a substantial increase in light emitted at wavelengths shorter than 500 nm, and a relative decrease in upward light emission due to better shielded luminaires. These results also demonstrate that earlier models relating VIIRS day-night band data to skyglow will – at a minimum – require substantial revision to account for the different characteristics of solid state luminaires.

Extract

The authors:

How do we convert to LED technology in a way that reduces energy consumption, reduces skyglow, preserves historical ambiance, and still meets the safety and security needs of our communities?

We believe with proper design and usage, energy savings and light pollution reductions can stand on the same side, both benefiting from LED retrofits. This study implies reductions in skyglow will require lowering overall light level (>50%), using warmer lights (< 3000 K), or both. Perceived conflicts between streetlighting objectives and light pollution can be further mitigated through controls that dim lights during periods of low traffic. More case studies are needed to pinpoint the exact criteria for a lighting retrofit to reduce skyglow. Nonetheless, a strong proactive lighting design is the key to converting to LED lights without increasing light pollution.

https://www.sciencedirect.com/science/article/pii/S0301479721008380

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Campaigners want government agencies and companies to turn off the lights so citizens can rediscover the beauty of darkness.

SOPHIE KNIGHT NOVEMBER 18, 2019

AMSTERDAM—As winter creeps across the Northern Hemisphere and daylight hours dwindle, it can be hard to appreciate the long, dark nights. But in the Netherlands, there’s a national campaign to embrace the darkness.

Nacht van de Nacht (Night of the Night) culminates in an annual event—this year, it was on October 26—during which local governments and companies turn off their lights and people gather in towns and woods to savor the absence of artificial light.

Earth Hour, a worldwide event to turn off the lights for one hour in March, is aimed at raising environmental awareness, but the goal of Nacht van de Nacht is to change lighting habits permanently, so that we can see the stars again.

This year, around 45,000 people took part in some 550 activities, including night walks in forests, star viewings, and candlelit dinners. The organization also holds workshops year-round and advises the government, municipalities, and companies to dim or turn off lights, and to adopt a policy of “Dark where possible, light where necessary.”

Excerpts:

Read the full article at:

https://www.citylab.com/life/2019/11/dark-sky-night-stars-netherlands-light-pollution-map-nacht/601846/?fbclid=IwAR0iykJlcWMe24n1bRZexY9j61Qvcs8LntAOsfOYPQkKu070D77kzbebcE0

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While the use of LEDs is becoming more widespread for lighting and LED objects are on the increase, ANSES published the update of its 2010 expertise on the health effects of LEDs in light of the new scientific knowledge available.

The Agency confirms the toxicity of blue light on the retina and highlights effects of disturbance of biological rhythms and sleep related to an exposure at night or at night to blue light, especially via screens and in particular for children.

The Agency therefore recommends limiting the use of LED devices that are the richest in blue light, especially for children, and reducing light pollution as much as possible to preserve the environment.

ANSES discusses: see https://www.anses.fr/fr/content/led-les-recommandations-de-l%E2%80%99anses-pour-limiter-l%E2%80%99exposition-%C3%A0-la-lumi%C3%A8re-bleue

New highlighted effects related to the blue light of LEDs

Change regulations and better inform the public about the risks associated with exposure to blue light

An impact on biodiversity and the environment

EMFSA’s translation of the above:

For more information:

-Press Kit PRES2019DPA01

-ANSES OPINION and REPORT on the effects on human health and the environment (fauna and flora) of systems using electroluning-light-emitting diodes (LEDs):

https://www.anses.fr/fr/system/files/AP2014SA0253Ra.pdf

-Effects on human health and the environment (fauna and flora) light-emitting diodes (LEDs)

https://www.anses.fr/fr/system/files/AP2014SA0253Ra-Anx.pdf

Toxic effect on the retina and disturbed sleep rhythm … these are the harmful effects. Some types of LED lights (light-emitting diodes), rich in “blue light”, have a toxic effect on the retina and disrupt our rhythm. sleep, warned this Tuesday the health security agency ANSES, which recommends to “limit the use”, “especially for children.”
Inexpensive, energy-efficient, long-lasting, LED lights “are expanding considerably” but are not safe, says the National Agency for Food Safety,  Environment Safety. and Labour (ANSES) See more at the link:

https://www.ledauphine.com/france-monde/2019/05/14/les-led-riches-en-lumiere-bleue-nefastes-pour-notre-sante

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