The Commission for Dark Skies

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Blue-rich LED Lighting — Bright New Future?

LED Streetlight


Artificial lighting is undergoing a radical worldwide change toward high intensity LEDs. These appear to have many advantages: cheap, energy-efficient and easily controlled; but novelties in the environment often have hidden costs. Do potential risks to health, wildlife and the enjoyment of the stars caused by the blue-rich white types of LED lighting justify the rewards?

Atmospheric light scattering makes the sky blue in daytime but causes sky glow from artificial light at night. Violet-blue light (390 nm) scatters 16 times more than warmer red light (780 nm). Many LEDs produce harsh, often over-bright blue-white light, scattering high into the atmosphere. This can cause more sky-glow than previous warm orange (low colour-temperature) lights: the benefits of otherwise good downward direction of light may be negated by blue-richness, over-brightness and glare. The result will be the veiling of the night sky, as excessive light from road lamps reflects upwards; or emissions from private lighting, much of which has no directional light control, go directly into the environment and the sky from poorly designed lamps.

Other important negative effects of blue-rich light include:

Badly designed LED light on hospital wall

The precautionary principle

UNESCO's Earth Charter states that the prevention of harm before it happens is the best method of environmental protection. When knowledge is limited, apply a precautionary approach:
a. Take action to avoid the possibility of serious or irreversible environmental harm even when scientific knowledge is incomplete or inconclusive.
b. Place the burden of proof on those who argue that a proposed activity will not cause significant harm, and make the responsible parties liable for environmental harm.

The worldwide introduction of blue-rich LED lighting has involved almost:

Had humanity allowed the introduction of agents, such as new gasses or chemicals, into the environment without applying precautions, then there would be outcry. Who will pay if it turns out that people suffer and many of the new lights need to be replaced?

The Commission for Dark Skies calls for: