s a child growing up in Mexico City, Alexandra Ponette-González often saw the thick yellow haze that sits in the basin. And she could sense it, too.
"I suffered from headaches, burning eyes and a dry nose," she says. "You see it, you feel it and you smell it. I have vivid memories of ozone action days, days it was recommended we not go outside. There were many of them."
It was in high school that she became interested in environmental issues and how to solve them. Now as an associate professor of geography and the environment, she is examining innovative ways to combat air pollution.
She is one of several UNT faculty members and alumni researching a problem that affects nearly the entire world. Air pollution can lead to a range of dangerous effects, from asthma to cancer to chronic obstructive pulmonary disease to weight gain. One in eight people will die due to the effects of air pollution, according to the World Health Organization. And air pollution can have negative effects on crop yields and forests.
"We should all care about air pollution because it affects our health and the ecosystems upon which we depend," Ponette-González says. "It can affect everyone in very real ways. It affects the economy. It affects our children."
And UNT researchers are determined to beat it.
"There are millions of solutions," Ponette-González says. "Our solution is to remove it from the air."
Anyone can be part of the solution. One of Ponette-González's projects involved different parts of the Denton community -- the UNT campus, city parks, homes and even Boca 31, a popular Latin food restaurant.
Those sites were used to help Ponette-González learn more about how trees can help fight air pollution.
"I like to think about what goes up in the atmosphere, what comes down, where it lands, when it lands and why it matters," Ponette-González says.
Anything can go into the atmosphere, good or bad -- soot, dust from the soils of West Texas, salt from the ocean, sulfur dioxide and microplastic -- and then fall out of the atmosphere naturally or in rain.
She wondered about the black carbon emitted from vehicles, wildfires and other sources. Where does the soot go? Industry uses scrubbers, such as spray towers, to clean out pollutants. Could trees and forests play a similar role and serve as urban air filters? Now in the fourth year of a five-year $534,263 CAREER Award grant -- the most prestigious recognition presented by the National Science Foundation for young researchers -- she is finding answers.
Her team gathered 400 samples of soot on leaves picked from live oak and post oak trees around Denton. After they collected the data, they conducted research in the Ecosystem Geography Lab.
The results? Annually, the trees could potentially remove more than 30 percent of the black carbon emissions from Denton's car fleet. And when the leaves drop from the trees to the ground, the soot they've collected becomes part of the soil. While black carbon adds harmful pollutants to the air, it can actually help soil by sticking to nutrients and keeping them from being washed out.
Her team included Jenna Rindy ('18 M.S.), Cassidy Winter ('17) and Brett Luce ('18). Another member, Tate Barrett, worked on the project while he was a postdoctoral fellow in UNT's Department of Geography and the Environment from 2016 to 2019. Now he heads the McKinney-based consulting firm Barrett Environmental, which offers indoor and outdoor air quality monitoring and assessments. It also recommends resources for those who live with asthma or COPD.
Prior to the study, he never thought about using trees as a solution in reducing emissions.
"As a homeowner, I discovered if I could plant some trees, I can plant some barriers," Barrett says. "It's a natural line of defense."
It's just one of several projects in which Ponette-González has been involved. One combined UNT's culture of innovation and collaboration across disciplines. Claire Pitre ('19), a geography major who studied under Ponette-González, examined how much soot externally accumulates on bird feathers.
Pitre collected feathers that had been shed from chickens, then cleaned and sewed them onto wire frames and placed them near Interstate 35 and a heavily trafficked bus stop -- where they served as both research and an art exhibit. After five days, Pitre picked up the frames and found that they contained measurable amounts of black carbon.
Then artists in the College of Visual Arts and Design used their talents to convey the meaning of the project. Dornith Doherty, University Distinguished Research Professor, created a time-lapse video from the cameras placed near the screens. Anna Lee, an undergraduate research fellow in studio arts, made raku pottery, a special method in which patterns are burned into the ceramics. Both Doherty and Lee captured the soot's deposits by photographing the feathers with a scanning electron microscope.
"Collaborating with an artist makes science more accessible to the public," Pitre says. "It's a challenge to try to explain global warming and atmospheric pollution. Having a visual makes the science real for people."
A day with high air pollution can increase an individual's blood pressure and risk of stroke, according to the Centers for Disease Control and Prevention. But it also poses another threat -- weight gain.
Diet and genetics are, of course, factors known to contribute to obesity. But Amie Lund, associate professor of biological sciences, is currently investigating if increased inflammation in the cells or tissues caused by exposure to air pollution also contributes to weight gain. She is in the middle of research from a three-year, $437,964 Academic Research Enhancement Award from the National Institutes of Health and its National Institute of Environmental Health Sciences.
Using an inbred strain of mice, she studied two groups -- one group on a high-fat diet and the other on a low-fat diet -- that were exposed by inhalation to a mixture of gas and diesel emissions. When she looked at the weight and fat cells of the animals, Lund noticed the difference.
"Exposure to air pollution appears to promote fat cells and store more fat, increase inflammation and alter signaling pathways within the cells," says Lund, who works in labs at the Environmental Education Science and Technology Building and the Science Research Building.
Lund also saw changes in these pathways in the low-fat animals -- considered the equivalent of a young, healthy adult -- albeit to a lesser degree than those animals consuming a high-fat diet. One of these is the renin-angiotensin system signaling pathway, which helps regulate blood pressure and could lead to hypertension when the pathway is overactive.
How can this be prevented? Environmental regulation and filtration systems can help minimize exposure to the pollutants. Also, drugs currently available can target the reduction of renin-angiotensin signaling in the body, but it is unclear if they also can provide beneficial outcomes in altering the signaling of fat cells in obese patients.
"It's important to understand how environmental factors are driving the response in the fat cells," Lund says. "Until we understand which factors may contribute to obesity, we can't address them."
She says the overall goal is to establish toxicity guidelines for environmental pollutants. That can assist with setting regulatory limits for environmental exposure in order to reduce adverse human health.
The possibilities for investigating the effects -- and solutions -- of air pollution are endless. But that doesn't deter the researchers.
"It's exciting," Lund says. "We're just scratching the surface. There will always be the next question to answer."
Student Researchers Work to Find Solutions
Five biological sciences doctoral students at UNT are leading the way to study the health effects of air pollution in different parts of the body.
The lungs, for instance, are the first to encounter foreign agents in the air. Sarah Daniel is exploring the involvement of the microbes within the lungs that play crucial roles in stimulating immune responses -- and often lead to chronic lung diseases.
Additionally, pollutants can alter the good bacteria that live in the gut. Danielle Phillippi ('15) is investigating the use of probiotics to treat the effects.
"Science has shown that healthy digestion is important in overall health, including mental health," she says.
Leah Schneider's ('16) research area is the liver, the "clearinghouse" where everything that enters the body is metabolized. She is working to understand how vehicle emissions can alter metabolism.
Usa Suwannasual is focusing on the brain, working to determine if air pollution promotes blood-brain barrier disruption and neuroinflammation, both of which are associated with strokes.
Also concentrating on the brain is Anna Adivi, who is researching the effects of air pollution on pathways associated with multiple sclerosis. The autoimmune disease has a higher frequency in females, and Adivi's research is the first to focus on the interaction between hormones and air pollutants in a female mouse model.
"The findings from each of these studies will contribute to our overall knowledge of how exposure to environmental air pollution can cause toxic effects in the body leading to disease," says Amie Lund, associate professor of biological sciences. "They also will provide insight into the disease pathways and may help identify key targets for pharmaceutical therapy or prevention."