LED streetlights are all the rage because they save money, lessen energy use, last long, and can be aimed judiciously. Yet all LED fixtures are not created equal. One characteristic in particular--the color--should cause you to choose with care. The harsh blue-rich light is more harmful than the soft redder hues. Please, select LED lights rated 3000K or less, whether for at home or for community-wide streetlights. Changes are coming your way, and you have both a choice and a voice.
The American Medical Association (AMA) made its position clear in announcing AMA Adopts Guidance to Reduce Harm in High Intensity Street Lights in June 2016, encouraging "communities to minimize and control blue-rich environmental lighting by using the lowest emission of blue light possible to reduce glare." While citing the road hazard of decreased visual acuity and decreased safety from high-intensity LEDs, the AMA also noted the adverse impact on the human body, including suppressing melatonin production at night and impinging upon the circadian system. The science behind the AMA position is in the Council on Science and Public Health CSAPH Report 2-A-16.
Primer on LED Packaging
On the label of an LED package you'll find a rating system for temperature in degrees Kelvin. The Correlated Color Temperature (CCT) indicates the relative color of the light. For example, a light rated 4000K or 5000K is of a bluer hue, sometimes dubbed "cool" or "daylight". A light rated 2700K or 3000K is a redder hue, sometimes dubbed "warm" or "soft" light.
A Department of Energy Lighting Facts label shows how temperature correlates to color. The human eye is exceedingly sensitive to light and color, so I personally think the label exaggerates the extremes when the lighting is actually put into practice. Typical sodium vapor streetlights are around 2200K, which is off the chart to the left.
Challenge the NIPSCO Standard
Communities across the region are being asked to choose what new streetlights will replace their existing high pressure sodium fixtures, with the replacements to be a permanent part of the landscape for decades. NIPSCO is embarking on an LED Street Light Program that intends to swap out all of its old 2200K fixtures with LED fixtures by 2022.
The NIPSCO website lists "a number of advantages over traditional, high pressure sodium street light sources," which are true, but it fails to acknowledge the shortcomings of its standard 4000K replacement compared to the alternative 3000K light fixture. While it claims, "NIPSCO-owned street lights will be changed at no additional cost to participating communities," in defaulting to 4000K LEDs the campaign actually imposes a likely long-term cost.
Please circle the preferred LED Light Correlation Color Temperature:
4000k (Std offering) 3000k (Alt offering)
Please, if you are authorized to select the future lighting of your community, choose the 3000K alternative lighting. The standard 4000K lighting is bluer and more detrimental.
All of the streetlight options provide plenty of illumination. NIPSCO says, "LED lights produce a light that appears whiter, similar to moonlight. The result is a more uniform light pattern." If you've stood outside in the light of just a full moon, you realize how surprisingly bright it is. The light of the full moon yields less than one lumen per square meter, or 1 lux. Now compare that to the number of lumens each streetlight puts out. Don't worry about lumens; there will be plenty, as mandated by engineering standards. Raise your voice, however, regarding the Correlated Color Temperature (CCT).
In addition to changes with utility-owned lighting, individual communities are opting to convert existing lighting to LEDs. For example, New Buffalo, MI, is going with an LED fixture as part of its downtown redevelopment initiative. The New Buffalo Times reports in its 2018 February 7 issue that the Downtown Development Authority (DDA) will select its preferred streetlight at a February 8 meeting, then make their recommendation to the City Council at its February 21 meeting.
Blue-rich light can change the entire character of a once-charming nightscape into a harshly-lit eyesore. It's like the difference between the blue LED headlamps in newer cars compared to the warmer lights of older models, as seen from the perspective of the oncoming traffic. Having lights with the lower temperature does not mean you have low light levels striking the target; it only means the light is more comfortable to the eye than the blue-rich variety.
For more background on lighting issues and dark sky advocacy, I invite you to peruse through past blog posts tagged "dark skies." Thanks for your consideration.