Curious Iowa: What light pollution regulations are in place for Cedar Rapids?

With the holiday season well-underway and the urban sprawl continuing to grow, experts are predicting an uptick in light pollution.

But what is light pollution and how is it controlled?

That’s what one curious Iowan asked The Gazette’s Curious Iowa series, that works to answer readers’ questions.

What is light pollution?

Light pollution is when the night sky is brightened by human-made lights, which disrupt night sky visibility, nocturnal animals’ biorhythms and the study of astronomy. It also can have adverse impacts on human sleep and health.

Jenny Ziegler Baker, a professor in civil construction and environmental engineering at Iowa State University, said not only is light pollution an issue, but “light trespass” is as well.

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Ziegler Baker described light trespass as “throwing light around where you don’t need it,” whereas light pollution is when light is thrown upward into the sky.

“I often say that light trespass happens when light goes beyond your property line. You want to keep it on your property when it's your light,” Ziegler Baker said.

Essentially, light trespass is a type of light pollution.

Ziegler Baker said one of the most common ways Iowans contribute to light pollution or light trespass is by using light fixtures that don’t have a “cut off,” or design to prevent light from being emitted upward.

She said ideal lighting for home or property owners are lights that cast light downward. Ziegler Baker recommends that when Iowans are purchasing new outdoor lighting, they buy an option with a “hood” over the top.

Overall, though, Ziegler Baker said bigger cities and urban areas tend to have more light pollution, whereas more rural, agricultural areas have less light pollution, due to few buildings and big industries.

What restrictions are in place for Cedar Rapids?

Seth Gunnerson, zoning administrator for the city of Cedar Rapids, said the city adopted a new zoning ordinance in 2019 that includes a more “robust” section dealing with lighting requirements.

That section requires light fixtures in parking lots and exterior lights on buildings to have a full cutoff, so light is projected only downward.

The ordinance also requires lights to be “shrouded,” so, for example, a streetlight does not have a naked light bulb at the top of the pole, he said.

Gunnerson said Cedar Rapids looked at other city’s guidelines when drafting new regulations.

Gunnerson said new commercial and industrial developments in the city must map out the exterior lighting to demonstrate the lighting will not contribute to light trespass. Some of the light regulations depend on what you are next to, Gunnerson said.

Some of the restrictions include 0.5-foot-candles for residential use and 1 foot-candle if next to agricultural or industrial use.

Lighting like this is measured in “foot-candles,” Ziegler Baker said.

A foot-candle is the measure of light intensity from 1 square foot of a light source. For example, a typical 100-watt light bulb is about 25 foot-candles at a distance of 8 feet.

Gunnerson, who has been working with the city for 13 years, said conversations around responsible light use and light pollution have become more prominent in the last few years.

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“It was in part because there were a decent number of situations where a new building opened up and it was very bright, and residents started complaining,” he said. “And our code at the time was either unclear about what to do with that or didn't really give us much teeth in terms of what enforcement mechanisms we might have.

“Ultimately, the goal was to give a standard for what our staff should look for.”

Gunnerson said the new code went into effect in 2019, but the ordinance itself was developed between 2016 and 2018.

He added that light pollution or trespass violations are compliance-based.

“If there's a complaint, someone (from city code enforcement) will investigate it to see if there's a violation,” Gunnerson said. “Generally, most enforcement that goes through the city is that someone gets a notification letter, and the city will work with them to correct it before it moves on to a fine or anything like that.”

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He said that “any type of municipal infraction could lead to a code violation,” like withholding permits or having a municipal infraction filed against someone, but the city works with citizens to resolve issues before it moves to that.

Greg Buelow, code enforcement manager for the city said, there were five light-related complaints in 2023 and 11 so far this year, as of Nov. 25, for light trespass-related violations.

“We recommend neighbors communicate with each other, which usually resolves the issue,” Buelow said in an email to The Gazette. “Many times, the lights look brighter than they actually are with regards to the amount of illumination measured at the property line, especially light-emitting diodes.”

How do lights affect sleep, health?

Jun Wang, chair of the University of Iowa’s Department of Chemical and Biochemical Engineering and a James E. Ashton professor in the College of Engineering, said light pollution holds implications beyond a brighter night sky.

One of the biggest implications of light pollution, he said, is how it affects the human body.

“As humans, when we sleep, we tend to sleep in a very dark environments and because of a more modern civilization, we have more and more artificial lights around us all the time,” Wang said.

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Wang said too much light pollution also can affect circadian rhythms, which can lead to insomnia, depression, anxiety, obesity and heart disease.

But on the flip side, some artificial light in cities is needed, Ziegler Baker said.

“We need to light roadways and sidewalks and places where there are pedestrians and vehicles,” she said. ”Those are places where it’s most important to have some extra illumination for safety and security reasons.“

Olivia Cohen covers energy and environment for The Gazette and is a corps member with Report for America, a national service program that places journalists in local newsrooms to report on under-covered issues.

Comments: (319) 398-8370; olivia.cohen@thegazette.com