Five years ago, a TV news story sparked a change in Mohammed Baalousha’s research.
A professor of environmental health sciences in the University of South Carolina’s Arnold School of Public Health, Baalousha studies the safety of engineered nanomaterials — ultra-tiny particles designed to do everything from delivering drugs into human cells to improving electrical conductivity in computer chips. He was particularly interested in understanding how such particles seep into water and soil and how they might impact environmental and human health.
Then one evening, while he was explaining his research to his 8-year-old daughter, a news story about California wildfires grabbed his attention. That was in 2020, long before the most recent wildfires in and around Los Angeles overtook headlines and captured our attention, but the problem was already a serious one.
“My daughter was talking about nanomaterials, I was seeing fires, and I realized I wanted to link them together,” Baalousha says. “I wanted to look at how fires impact the formation of nanomaterials, what kind of nanomaterials are generated during fires and how they get released into the environment.”
The devastation on TV was occurring in the western United States, but Baalousha knew that his research would be relevant nationwide, including in the Southeast.
The western United States may be ground zero for wildfires in the U.S., with hundreds of thousands of acres burned each year due to the dry climate, but wildfires are not uncommon in South Carolina. In a typical year, according to the South Carolina Emergency Management Division, firefighters respond to more than 5,000 wildfires across the Palmetto State. While the fires tend to burn much smaller areas compared to those in the western U.S., climate change could lead to larger burn areas in South Carolina.
And even when they don’t happen in the state, fires elsewhere can still impact air quality. The 2023 Canadian wildfires led to air quality alerts across the U.S., including in South Carolina.
Since shifting gears, Baalousha has learned a lot about what happens to nanomaterials and metals when they burn. He and his colleagues have been studying soil, ash and water samples from major California disasters, including the 2020 LNU Lightning Complex and North Complex fires, research that is supported by a National Science Foundation grant. Then, after a devastating wildfire tore through Maui in August 2023, Baalousha received another National Science Foundation grant to study samples from there, too.
“Because it's right at the coast, there were a lot of concerns about these materials flushing into the ocean, impacting coral reefs and so on,” he says.
The list of related research projects has continued to grow. Recently, he and other scientists from the California State University, Chico and the University of California, Davis, received funding from the National Science Foundation to collect and archive ash, soil and water samples from the Park Fire, which consumed 429,000 acres of wildland in Northern California.
In collaboration with colleagues at the Université Laval in Quebec, Baalousha also investigated the release and dispersion of nanoplastics and metallic nanomaterials from open-air waste combustion, a common waste management approach, in Canadian Indigenous Arctic communities.
Closer to home, he and a multidisciplinary team of USC researchers have also partnered with researchers at Clemson to gather data from two burn sites in South Carolina. That project, he hopes, will shed light on how contaminants from lower-intensity prescribed burns differ from those produced by wildfires. Additionally, he is leading another NSF project, in collaboration with Susan Richardson in the chemistry and biochemistry department, to investigate how wildfire intensity impacts metal transformations and mobilizations along with the formation of byproducts.
The biggest thing we started learning, and it scares me sometimes, is when you burn materials, they completely change. Materials in the structures or in the trees that are naturally benign — metals like chromium or arsenic, for example — can be present in one form before the fire, but the fire transforms them into potentially more mobile and more toxic forms.
Some data from these projects has been published in journals including Environmental Science and Technology and Journal of Hazardous Materials. Other analyses are ongoing, but his team has already made surprising discoveries into how wildfires impact the surrounding environment.
“The biggest thing we started learning, and it scares me sometimes, is when you burn materials, they completely change,” he says. “Materials in the structures or in the trees that are naturally benign — metals like chromium or arsenic, for example — can be present in one form before the fire, but the fire transforms them into potentially more mobile and more toxic forms.”
Take arsenic, which most often occurs as arsenic(V) in the environment. Baalousha’s team has found that wildfires convert some of the arsenic(V) into arsenic(III), a form that is more mobile and more bioavailable. When colleagues at the Environmental Protection Agency recently reported seeing higher arsenic concentrations in aquifers near burn areas, he wasn’t surprised.
“That could explain why this is happening,” he says. “Because if the arsenic goes from arsenic(V) to arsenic(III), it becomes more mobile, and when it rains, it gets flushed into the groundwater.”
Not all fires are equal when it comes to environmental contaminants. Vegetation fires result in less metal mobilization because trees absorb metals from the soil in low concentrations. Structure fires, on the other hand, are a mixed bag of materials with elevated metal concentrations — electronics, copper pipes and treated wood, to name a few. That’s a concern in places like Maui, where more than 2,200 structures were destroyed, according to the U.S. Fire Administration.
What does this mean for our health? Research has shown a link between fire exposure and dementia as well as increases in hospitalizations, cardiovascular disease and respiratory disease. Baalousha believes some health issues could be related to metal transformations during fires. For example, his team has found that wildfires can transform iron into magnetite, a particle that has been linked to Alzheimer’s disease. And fellow Arnold School researcher Sean Norman found that metals in wildfire ash can alter bacterial growth and gene expression, potentially increasing antibiotic resistance.
Baalousha is also collaborating with colleagues at the Arnold School and with Mohamad Azhar at USC’s School of Medicine Columbia to further understand the impact of metal and nanomaterial transformations in wildfire on metal uptake in aquatic organisms and cardiovascular disease.
Understanding these potential dangers is necessary as wildfires worsen. Since the mid-1980s, the total area burned by U.S. wildfires has steadily increased, and today fire season peaks a full month earlier than it did 40 years ago, according to the EPA. Case in point: This year’s devastating Southern California fires are unusual for January.
“Now the fire season is becoming longer and longer,” Baalousha says. “I was at a conference recently, and they were saying that we’re moving from a fire season to a fire year. There could be consistent exposure for a longer duration, and the longer you expose people, the more they’re breathing in.”