Monthly Archives: March 2019

Knoxville LED Project Harms Insects, Foundation of Life as We Know It

Today’s issue of “From the Desk of Mayor Rogero” notes the City’s work to replace all 30,000 street lights with LED fixtures is halfway done.

City of Knoxville contractor installs LED street light. Photo: City of Knoxville.

Unfortunately, the LED project has serious negative impacts that might have been identified and addressed had community input been earnestly sought (zero public meetings, dismal public outreach).

The City’s response to concerns raised as the lights began going up is “too late.”  It’s an easy answer if you minimize the importance of public participation in decisions carrying lasting consequences.

Council already voted for the street lights; half of them are already installed. So I am asking you to take two steps that could make a difference now:

  1. Please ask the Mayor for 20 “wildlife sensitive” LED street lights for Sharp’s Ridge Memorial Drive. The color output of these lights is akin to Knoxville’s existing sodium vapor lights, and since Sharp’s Ridge Memorial Park is closed from dusk to dawn, criticism of luminous output from “wildlife sensitive” lights is not a legitimate concern.
  2. Please be aware of the detailed information below illustrating why ask #1 is so important. While Knoxville may be locked in to Mayor Rogero’s selection of LED fixtures for the next ten years, the public should be aware there are alternatives minimizing the negative impacts of LED street lighting on native wildlife populations, particularly insects and birds.

Here’s why I’m bothering to write– a recent headline in the national news that “Massive insect decline could have ‘catastrophic’ environmental impact”

While journalists often favor sensational headlines, scientists are raising alarm too, calling the problem of insect declines “hyperalarming” and “gravely sobering.”At the going rate (2.5 percent biomass loss per year), scientists say 40 percent of insect species may go extinct over the next few decades.

In the words of an entomologist, “No insects equals no food,” and no food means “no people.”

Insects feed a lot of animals– including people.  Per the U.S. Department of Agriculture, insects pollinate crops that produce more than one third of the world’s food supply. Insect pollinate three quarters of all the world’s flowering plants.

Scientists suspect light pollution in cities plays a role in declines“Scientists have now discovered that regions that have experienced a sharp decline in flying insects also have high levels of light pollution.”

Science says artificial light at night “has strong potential to negatively impact rates of insect survival by interfering with reproduction, communication, and fragmenting insect populations.”

“Artificial light may be devastating populations of insects, including species that provide crucial support for human agricultural systems,” according to a study published in the Annals of Applied Biology in June 2018.

If you’ve ever seen insects swarming around a porch light– you know the big effect artificial light can have on insects. 

Many insects are drawn to light, the proverbial “moth to a flame,” and become “trapped” in the light where they are eaten by predators or simply die of exhaustion.

Crucially, about half of the world’s insects are nocturnal. “As such, they depend on darkness and natural light from the moon and stars for orientation and movement or to escape from predators, and to go about their nightly tasks of seeking food and reproducing,” Maja Grubisic, who led the latest study, said in a statement ( . “An artificially lit night disturbs this natural behavior — and has a negative impact on their chances of survival”.

What does Knoxville’s LED streetlight project have to do with insects?

High Pressure Sodium (left) and new “cool white” LED on Broadway in Knoxville.

Both humans and insects are negatively affected by the “color temperature” of lights (recall the difference between the “warm orange” glow of a bonfire and the “cool white” of a florescent light).

Knoxville’s existing lights are largely sodium vapor lights– the “color temperature” of which is more akin to light emitted by the warm glow of a fire than the cool white light of a florescent bulb.


Knoxville’s new LED street lights have a significantly higher “color temperature”– casting much more “white” light than the old sodium vapor lights.

Current science says animals and people are more sensitive to higher color temperature lights (again, “high” color temperature means more “blue” and “white” light.)  “Cool” blue light is known to have greater negative affects on insects, while “warm,” more orange light is known to have less negative affects.

The best available science says Knoxville should use the lowest color temperature lights possible (“warmest” perceived color) while still achieving the light’s intended function.

Lower color temperature lights are in fact *available* to the City; the City simply took the manufacturer’s word the lights were “for coastal areas.”

I have been in communication with a leading U.S. scientist on light pollution and its impact on wildlife.  He assured me– and even wrote a blog post about Knoxville’s situation– that warm color temperature light is better for insects, even in non-coastal areas.

I have forwarded this information to the Office of Sustainability and reached out to Council members in districts with the most ecologically sensitive areas already.

Despite the insect decline crisis, despite the impacts of “cooler” color temperature lights to wildlife and people, the City’s position is it’s too late to change anything.

20 street lights on Sharp’s Ridge Memorial Drive

I submit to you it’s not “too late” to do something about the problem with Knoxville’s 30,000 new LED street lights: just twenty low color temperature “wildlife sensitive” lights (already available from the manufacturer Knoxville contracted with for the project could be installed at the most environmentally sensitive location in the City (Sharp’s Ridge Memorial Drive).


I have also proposed lower color temperature lights be used on residential streets, as has been done in Washington, D.C.

Washington  D.C. LED Street Lighting Plan

Knoxville’s Office of Sustainability argues the new lights fit the American Medical Association’s and International Dark Sky Association’s recommendations.

That’s true– the new lights fit the *minimum* recommendation from both groups.Yet, the International Dark Sky Association also posted in July 2018 concerning the “Ecological Armageddon” of insect declines: is Knoxville doing the “bare minimum,” when the foundation of our food security– healthy insect populations— are at risk?

We can do better in Knoxville.

I get that Knoxville isn’t the “leading edge” in the nation, but we are home to Tennessee’s land-grant institution. Maybe we can’t do all 30,000 at the lower color temperature, but we can surely do enough to make a difference.

Please, lend your voice in asking the Mayor to change course on the street lights.