Estimated read time: 4-5 minutes
SALT LAKE CITY — Utah has some of the worst air pollution in the country at times during the winter inversion season. So, technology that promises to "eat smog" garners interest on those days when you can't see the mountains across the valley.
On one of those days, we investigated how other cities are managing their air quality. We found cities all across the county are testing smog-eating pavement with impressive results.
"It is supposed to help combat greenhouse gas emissions," said Ben Griffin, street maintenance manager for the city of Raleigh, North Carolina.
In 2020, Raleigh treated 12 miles of pavement. Then, it monitored air quality samples and found between 28-40% reduction in greenhouse gas, depending on location.
"We're really, really pleased with that," said Griffin.
The city is treating dozens more miles in 2024.
The chemicals and minerals in smog-eating roads are often added to pavement rejuvenation products. One of them, titanium dioxide, is the same stuff in sunscreen.
When sun hits the titanium dioxide, it sparks a catalytic reaction. Energized electrons oxidize and break down harmful gases in the air, much like trees.
"One mile of the Plus TI technology, mile of road, is like planting 15 to 20 acres of carbon and nitrogen-removing trees," said Michael Durante, with Pavement Technology Inc.
The company has partnered with universities like Texas A&M and Purdue to independently verify similar results in cities like Raleigh; Charleston, South Carolina; Orlando, Florida; Cleveland, Ohio; San Antonio, Texas; and Tucson and Phoenix, Arizona. Company leaders say the amount of emission reduction in those cities ranged from 28% to more than 54%.
We traveled to Phoenix to learn about its experience with smog-eating pavement. The city's problem isn't winter inversions, but summer heat. But officials found the reflective pavement addresses both.
"We've surpassed our 100th mile installed," said Ryan Stevens, engineering manager for Phoenix's street transportation department.
Stevens oversees this project in the nation's fifth largest city. He says streets that reflect the heat of the desert sun are a "big deal."
"We had articles of people slipping and falling and getting burns when they come in contact with the street," he said.
The reflective treatment that makes the roads gray, not black, managed to reduce the street surface temperature by up to 12 degrees.
The city is no longer testing. The city of Phoenix is spending millions to "cool pave" neighborhood streets as fast as it can afford.
Clean air advocates say this dual purpose would address Utah's winter inversions as well as our increasingly hot summers.
"We actually have a big challenge that we're facing with our summertime air quality as well," said Kim Frost, executive director of air quality advocacy group UCAIR Utah.
Utah has another interest in the technology. Much of the titanium dioxide that makes these roads reflect the sun is mined here in our state. So, in a sense, Utah is helping to clean other states' air.
"It would be a real twist of fate if a place with such natural beauty as Utah ends up being a kind of savior," said Chris Evers, of Pavement Technology Inc.
For all the connections and seeming applications in Utah, many might wonder why we are not testing it here. It actually was tested years ago, for a short time, at the University of Utah.
"It was called smog-eating concrete," said concrete expert Amanda Bordelon, now an associate professor of civll engineering at Utah Valley University.
She said the technology worked, but testing showed limitations in Utah.
"We did prove that the product we were using was effective," she said. "The biggest downside is it seemed to only work in a climate that was humid."
Our arid climate had a drying effect on funding and research.
We took our question to the head of Utah's Division of Air Quality. He says the state would rather invest in things that it knows work.
"That's really what we're looking for is these big wins, where we get a big reduction in emissions with very little cost to the consumer," said director Bryce Bird.
Cities quoted us different costs for their smog-eating treatments. The city of Raleigh said the cost of adding titanium to their road conditioner is "nominal," about a dollar per square yard.
In Phoenix, it doubles the cost of their road product. But they say it is an investment they're willing to make.
"That reduction will make the city more sustainable, more livable," said Stevens.
