From Birth to Death Our Health and the Environment are Inextricably Linked, Jim Zhang's Research Shows in One Study After Another
During the 2008 Summer Olympics in Beijing, while the rest of the world was watching swimmers, gymnasts and other athletes go for gold, Junfeng “Jim” Zhang and his team had their eyes on a different prize.
Zhang, an expert in the field of exposure science, had temporarily set up shop in the Chinese capital to measure how improvements in the city’s air quality during the Olympics affected its residents’ cardiovascular and respiratory health.
Beijing is one of the world’s most polluted cities, but the Chinese government had promised to reduce pollution by shutting down factories and limiting traffic for a six-week period leading up to and encompassing the games.
“This was something no one had attempted to do on such a large scale before,” Zhang says. “We wanted to take advantage of such a huge intervention and look at what happens in people’s bodies when their exposure to pollution drops.”
To conduct the study, he and his colleagues measured blood clotting, heart rate, lung and systemic inflammation and other biomarkers of cardiovascular health in 125 young, healthy, nonsmoking medical residents who worked at a central Beijing hospital. They examined each volunteer six times: twice before the pollutioncontrol measures began; twice while they were in play; and twice after the games ended and air quality measures were relaxed.
The results were golden.
Zhang’s study, published four years later in the prestigious Journal of the American Medical Association, became the first to identify a biological link between air pollution and cardiovascular health.
“Inflammation, oxidative stress and other risk factors for heart disease were significantly reduced while pollutioncontrol measures were in play but rose again sharply when the measures were relaxed,” he says. “This was evidence that physiological changes occur rapidly in our bodies when we are exposed to changing levels of pollution.”
The take-home message was clear: Even short-term improvements in air quality can yield significant reductions in disease risks, not just among children and other higher-risk groups but in healthy young adults, too.
It was the latest in a series of breakthroughs that have catapulted Zhang, who joined the Nicholas School faculty in 2013, to the forefront of his field.
Since 1994, he’s published more than 150 studies examining the environmental and human health impacts of air pollution. His work has shed light not only on what the effects of exposure to pollutants are, but also how they alter the physical and biochemical processes that affect Earth’s climate and reduce or increase disease risks in our bodies.
He was among the first scientists to investigate hydrocarbon emissions and health risks from cookstoves in developing countries, and has led pioneering studies on a long list of other pollutants, as well, including diesel fumes on the streets of London; lead dust from pottery production in Mexico; volatile organic compounds from paint manufacturing in Kenya; hydrocarbon emissions from mosquito coils in China and Malaysia; perchlorate exposures in lactating women in New Jersey; greenhouse gas emissions and other airborne pollutants from charcoal making in Brazil and Kenya; and, most recently, engineered silver and carbon nanoparticles in consumer products in the United Kingdom and the United States.
“Indoor exposures, outdoor exposures—I’m interested in them all, particularly in cases where people work and live very close to the source of pollution,” says Zhang, 49, of his globespanning interests.
In recognition of his early work to characterize sources of non-methane greenhouse gases, Zhang was officially recognized as a contributor to the 2007 Nobel Peace Prize awarded to the United Nations’ Intergovernmental Panel on Climate Change.
In 2012, he received the Jeremy Wesolowski Award, the highest professional honor bestowed by the International Society of Exposure Science. In 2013, he was named a Fellow of the American Association for the Advancement of Science.
A follow-up study to his 2008 Beijing research may yield additional accolades.
The study, which Zhang and colleagues recently submitted to a leading environmental health journal, examines the impact of pollution reductions on pre-term birth rates and birth weights – another scientific first.
“We find that babies’ birth weights increased significantly if their mothers’ eighth month of pregnancy was during the 2008 Olympics, when air pollution was reduced for six weeks,” he says. “Even a temporary reduction made a statistically significant difference.”
It’s further proof, he says, that from birth to death, our health and the environment are inextricably linked.
A Growing Global Threat
The urgency of Zhang’s work is underscored by a World Health Organization (WHO) report released earlier this year. The report estimates that in 2012 about 7 million deaths, or roughly one in eight premature deaths worldwide, were caused by air pollution—more than from malaria, tuberculosis and AIDS combined.
The new estimate of pollution-related deaths is more than twice that of previous WHO estimates, and establishes airborne pollutants as the world’s single largest environmental threat to human health, particularly in developing countries and large cities.
Emissions from carbon-based fuels account for most of the risk. But new threats may be emerging.
“Manufactured nanoparticles are being used in all kinds of consumer products, from fuel additives to sunscreens to sporting equipment, but we’re only beginning to understand how they interact with the environment or might affect human health,” says Zhang, who is heading two major research initiatives to find answers.
With $4 million in funding from the U.S. Environmental Protection Agency and the United Kingdom’s National Environmental Research Council, he’s directing a four-year laboratory study to assess the risks posed by engineered nanoparticles used in consumer products.
With $5 million in funding from the National Institute of Environmental Health Sciences, he’s leading a fiveyear lab study to understand the link between the physiochemical properties of nanoparticles and their toxicity.
“Our goal is to produce well-defined measurements of nanoparticle properties so we can better determine their risks,” he explains. “It’s not possible to test nanoparticles side by side, one to one, as we can with other pollutants. They’re too tiny and there’s too many of them. But if we know their basic properties— such as their sizes, shapes and structures, and if they’re water soluble or not—we can figure out relationships between those properties and toxicity, and provide guidance on how to design and manufacture safer alternatives.”
One of the initiatives’ most widely cited findings so far has been on the use of nanosized ceria additives in diesel fuel.
Ceria, or cerium oxide, is a metallic powder. Nanosized ceria has been used in recent years as a catalyst to improve combustion and increase fuel efficiency in diesel engines. Zhang’s team’s analysis, published in 2013 in the journal Environmental Science & Technology, suggests the jury is still out on whether the environmental benefits outweigh the possible risks.
“Nanosized ceria additives do reduce fuel use by 10 to 15 percent, meaning engines emit 10 to 15 percent less carbon dioxide emissions,” he says. But there’s a catch. “Even though we see a reduction in particle mass, we also see a shift from larger particles to smaller ones.”
These particles are so small they resemble a gas and not only can be inhaled into lungs but also can shoot directly into a person’s blood.
“We’ve essentially changed the emissions’ profile and the pathways they can take into our bodies,” Zhang says. “It’s too early to tell if this is a good thing or not.”
While lab studies on nanoparticles and other emerging sources of pollution occupy more and more of his time now, Zhang continues to pursue the meticulously constructed field studies on real-life exposures that have long been his hallmark.
A case in point is his ongoing study, first reported in 2007 in the New England Journal of Medicine, on how short-term exposure to big-city traffic exhaust alters lung functioning.
The project, which Zhang began in 2000, measures changes in biomarkers of respiratory health in people with asthma after they spend two hours walking along London’s busy Oxford Street.
“Our tests show that after two hours’ exposure to diesel traffic fumes, physiological changes occur in the volunteers’ respiratory systems. Their lung functioning drops temporarily by an average of 6 to 7 percent,” he says.
By comparison, rescue workers who responded to the 9/11 bombings of New York City’s World Trade Center lost an average of 10 percent of their lung functioning. The rescue workers’ decrease was far more debilitating and long-lasting, Zhang says, but it serves to illustrate “how serious the effects of even short-term exposure to big-city traffic exhaust can be, especially for people with a mild to moderate preexisting respiratory disease. Biology does not lie.”
These days, new research findings by Zhang and other leaders in the field can generate widespread buzz in medical, scientific and policy circles.
But it wasn’t always the case.
“My early presentations on cookstove emissions attracted very small crowds. Sometimes, it was just me, my mentor Kirk Smith and maybe one other person in the room,” Zhang recalls with a laugh. “It was the mid-1990s. Exposure science, especially indoor air science, was just emerging. I was one of only a few researchers worldwide looking at the cookstove exposure issue.”
And even he came to it somewhat circuitously.
After earning a bachelor’s degree in applied chemistry in 1985 from Peking University in Beijing, Zhang stayed on to pursue a master’s degree in atmospheric chemistry. He planned to study ozone pollution, which was a growing problem in many of China’s large cities.
“I was more interested in environmental applications than human health exposures,” he says. “But by the time I graduated with my master’s in 1988, my interests had broadened. I was becoming more aware of the human health impacts of air pollution, so decided I wanted to do something that bridged human health, environmental science and physical science.”
He enrolled at Rutgers University in New Jersey to pursue a second master’s degree in environmental science. He stayed at Rutgers for his doctoral studies, earning his PhD in exposure science in 1994 before heading west for a two-year postdoctoral fellowship with renowned global environmental health researcher Kirk R. Smith at the University of California at Berkeley.
“My training in exposure science up to that point had mostly been in hardcore theoretical science, but Professor Smith transformed my thinking,” Zhang says. “He helped me understand what is really important, and I began working much more on the applied side.”
Zhang’s earliest work focused on characterizing the sources of greenhouse gas emissions, but he increasingly became fascinated with the issue of indoor air quality.
“It was a new field, there were lots of opportunities, and the number of people affected was huge, especially women and children in developing countries,” Zhang says. “I started looking at the issue anywhere there was considerable exposure.”
A rapid-fire succession of peerreviewed papers followed, along with a steady rise up the ranks of some of the world’s leading centers for environmental health, including Rutgers and the University of Southern California’s Keck School of Medicine.
In 2013, he joined the Duke faculty with joint appointments as professor of environmental and global health at the Nicholas School of the Environment, the Duke Global Health Institute (DGHI) and Duke Kunshan University in China.
Today, he divides his time between the Durham and Kunshan campuses, managing research labs and teaching students at both.
In Durham, he teaches a master’s-level course on air pollution and will co-teach a doctoral-level course on exposure measurement and assessment next fall. In China, he teaches an “Introduction to Global Health” course.
When he’s not busy teaching, traveling, giving talks, managing research, writing papers, or writing grant proposals for new projects, Zhang enjoys spending time at home in Durham with his wife, Gloria, and their two sons, Charles, 14, and Barry, 12, photos of whom are among the few personal items on display in his still half-unpacked office in the Levine Science Research Building.
If he had spare time, he’d also like to take up a favorite old pastime again: writing poetry.
“When I was younger, I published numerous poems, mostly in Chinese but also a few in English,” he says. “I enjoy playing with language, the challenge it presents.”
A poem that he wrote in 1990 about his parents, “Memory: a Serenade,” won first place in the National Hongyu (Rainbow and Rain) Cup Contest of Poetry and Words in Beijing. The honor is prominently listed on page two of Zhang’s 44-page curriculum vitae, the same page as his Nobel Prize citation.
“It’s been years since I’ve written anything like that. I miss it, but after writing grants all day, you don’t have room in your brain to write something different,” he says as he politely turns and eyes the stacks of unfinished grant proposals on his desk and the evergrowing number of emails accumulating in his inbox. “You make your choice about what’s truly important.
“Someday, perhaps, I’ll have time to pursue poetry again. But if not, it’s okay,” he says contentedly. “I have more than enough to keep me challenged.”
Tim Lucas is senior writer for Dukenvironment magazine and is the Nicholas School’s director of marketing communications.