Down and Dirty: Understanding of Dust Pollution Hits Solid Ground With New Research

You can’t escape it, dust is everywhere. It covers Utah communities with a fine layer of grit. It gets whipped in the wind to snow-covered peaks where it absorbs heat and melts the snowpack. It settles onto rivers and reservoirs and peppers farm fields. It is pulled into the atmosphere where it crosses continents and invisibly inserts itself into almost every natural system.

“The public hasn’t been paying much attention to dust, but we should be,” said Janice Brahney from the Quinney College of Natural Resources.

Brahney is hoping to change the conversation around dust with a major synthesis of dust research in the journal Earth-Science Reviews that compiles research on dust pollution and details major gaps.

How much we know about dust depends on its size, she said. By federal mandate dust particles smaller than 10 micrometers are rigorously monitored, because they can be inhaled and have consequences for human respiratory health. Anything larger than that — approximately the width of a piece of spider silk — mostly flies under the radar, untracked and underestimated in its impact on the world, Brahney said.

Present-day dust levels are estimated to be up to 45 times higher than they were in the 1900s, although there is a lot of variability in the estimates. Dust pollution is likely to become more problematic largely because of human action and climate change, according to research. Things like construction, farming, grazing, deforestation and mining directly add particles to the atmosphere.

Climate change exacerbates conditions like drought and wind, leading to worsening dust conditions. Some “new” types of dust material like plastic comes from roads, agriculture and legacy pollution in the ocean where waste churn and spit microplastics into the air, and they blow inland.

Experts on “big” dust are still seeking answers to very fundamental questions, even as these pervasive particles increasingly impact everything from Utah’s water quality to plant growth.

For instance, researchers are still documenting what dust is — it’s more than powdered rock, Brahney’s work has proved. Eroding soils contain up to two-thirds live (or formerly alive) materials: bacteria, fungi, pollen, spores, insect and plant fragments, charcoal and algae. Dust from the Earth’s surface also commonly contains man-made substances; tiny pieces of plastic, wear from car tires and fertilizer.

Depending on its source, dust also sometimes carries heavy metals, salts and chemical nutrients like phosphorus, as Brahney’s previous research has shown. Kim Hageman, professor of environmental and analytical chemistry from the College of Science, and her doctoral student Jeff Perala-Dewey worked with Brahney and doctoral student Molly Blakowski on Great Salt Lake dust to quantify organic contaminants including pesticides, persistent organic pollutants, and hydrocarbons emitted from the playa.

Considering the consequences of a dust-filled world, why hasn’t it gotten more attention from researchers? Partly because many of them assumed that the larger dust particles didn’t travel far and were a local problem. But Brahney’s research and that of researchers from across the globe proves otherwise. Even “giant” particles move thousands of miles under certain conditions, she found. Relatively large pieces of microplastic are found in samples of Arctic snow, Texas dust in Florida, and in dust from Africa and Asia in the American West, other researchers have discovered.

Another reason the science has been slow to gain steam: It’s difficult to collect enough of this type of dust to study it. The occurrence of dust storms are unpredictable and relatively fast to diffuse into the broader atmosphere.

Current measurement equipment is designed to collect samples of small dust pollution, not the bigger particles that Brahney studies. To solve this, Brahney launched a major effort in collaboration with the National Atmospheric Deposition Program.

She developed and tested a new system to collect the bigger dust material, establishing collection points at 30 sites across the West and Midwest. The network is an ongoing collaboration to understand the composition of dust being deposited and its impacts on ecosystems

Brahney’s endgame is more than digging up dirt on this complex problem, she says. Ultimately she wants to change the way researchers fundamentally think about dust. Her work shows that dust has a critical role to connect and shape the Earth's environments: it is one of the few things that link all parts of the “Critical Zone” at the planet’s surface. Dust shapes soil and water systems, fertilizes ecosystems, changes the Earth's temperature and impacts human health and quality of life.

But the current official definition for the Critical Zone doesn't even include dust, which makes it harder for researchers to fully understand how the planet functions and to address problems like dust pollution, she said. Brahney acknowledges it would be a fundamental shift, but including dust in the definition for the Critical Zone would allow scientists to better study its wide-ranging impacts and create more effective policies for the environment and human health.

“Ignoring dust means missing a key piece of the puzzle in understanding our planet's life-supporting zone,” she said.