While LEDs (light emitting diodes) have quickly become the way to light the 21st century, extensive research has shown that there’s a “dark side” to this new type of nighttime lighting.

Due to their current design, the 3000K to 6500K (Kelvin) LEDs that are being installed across the country are causing many problems because this white light — actually blue-rich white light — is loaded with short wavelength blue and green light which has much higher environmental impacts. These short wavelengths are detrimental to us nocturnal mammals, insects, amphibians, reptiles, and the nighttime environment as a whole.

Our eyes are extremely sensitive to short wavelength blue and perceive this blue component as being 4 to 5 times more intense and lazy than the yellow-orange High Pressure Sodium (HPS) light that we’re used to seeing at night. It scatters more in our eyes, creating a “veiling” effect, making it more difficult to see. For older drivers and those with impaired vision, this can be a dangerous situation. Our visual system responds well to white light in the daytime — BUT NOT AT NIGHT!

Our dark adapted (night vision) eyes are much more sensitive to the shorter (bluer) wavelengths than light adapted (daytime) eyes. Light sources producing more blue light will appear many times brighter, and extremely glary, to our dark adapted eyes.

Even without changing the amount of light or shielding, switching a lighting installation from a High Pressure Sodium to 4100K LED increases skyglow as if the amount of HPS lighting had been increased by 170%, or nearly tripled. And research in Australia has shown that compared to other types of lights at night such as High Pressure Sodium and Low Pressure Sodium, LEDs attract 48% more insects — LEDs are an insect death trap — they suck the insects completely out of the environment. Even our old familiar incandescent bulbs weren’t this bad! For humans and all nocturnal creatures, the one thing we shouldn’t do when it comes to light at night, is to turn it into a “White Light” night.

The best type of light for outdoor lighting at night is High Pressure Sodium, as it causes the least environmental impact. Compared to blue-rich LEDs, the glare in our eyes will have lots less impact, too! But with HPS being phased out, the Phosphor-converted Amber LED (PCA LED), closely matching the same wavelength of HPS, is the best choice to replace HPS for street and area lighting.

Correlated Color Temperature (CCT) is a number used by lighting companies to identify the “perceived color” given off by light sources measured in degrees Kelvin (K). But it is not an accurate way to determine the actual amount of blue and green from any light bulb (lamp) or LED. CCT is a very crude way to describe how “warm” or “cool” a light appears to the human visual system. Lower temperature CCT appears “warmer” and more eye friendly, while higher temperature CCT looks “cooler” and “harsher” to our eyes.

There’s a quote: “The world runs on perception, not on reality.” Across the country, city / county leaders are rushing to install LEDs without any knowledge of outdoor lighting — LED lighting especially — and the complaints from citizens have been very vocal. With all of the extensive research done in the U.S. and Europe in the last few years, find out about this new type of lighting before making decisions that will last for 30 years or more. Go with the research and not with the “sales pitch” from your local utility; go with the facts and what your eyes tell you — not your perception. Because turning our cities and towns into perpetual daylight, 24 / 7 / 365, would be the worst decision leaders could make.

The complaints from citizens in cities that have installed LEDs have been heard. Some lighting companies have begun to address the blue-rich problem. But the best thing for leaders to do is not rush into making a switch to LED lighting; let the lighting companies get the blue-rich problem corrected.

In December of 2014, General Electric published a White Paper on the problems associated with blue-rich white LED lighting. And at the American Medical Association (AMA) meeting in June 2016, all 540 delegates voted unanimously to support “getting the blue” out of LEDs.

Best for light pollution (LP) reduction:

(1) Narrow-Band Amber LED (NBA LED). Narrow-spectrum yellow-orange, almost equal to Low Pressure Sodium in LP reduction. Best choice for cities near observatories.

(2) Phosphor-converted Amber (PCA LED). Similar to HPS and, if your city isn’t near an observatory, the best choice for lighting streets and area lighting.

(3) LED 2400K. A warm white LED that has not seen wide use.

(4) Filtered LED (FLED). Removes wavelength of light less than 500nm (nanometers).

For the latest research on the problems with LEDs, go to Flagstaff Dark Skies Coalition at flagstaffdarkskies.org and Illinois Coalition for Responsible Outdoor Lighting at illinois lighting.org.

This post was written by Francis Parnell.

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