When Jun Wu was a little girl, growing up in a rural area along China's Yangtze River in the 1980s, the air was very clean. "Every day after dinner," she says, "our parents took us out for a walk along the country road. We children enjoyed chasing dragon flies. It was very beautiful."

In contrast, Southern California in the 1980s had three decades of experience with air pollution, and children enjoying the "fresh air" during an after-dinner walk were also exposed to harmful pollutants. Among the researchers who were looking at links between exposure to air pollution and disease was Arthur M. Winer, who developed the Regional Human Exposure Model in the late 1980s with Fred Lurmann.

Today, Jun is a "bright, highly energetic, and imaginative young scholar" in the School of Public Health's Department of Environmental Health Sciences, according to Professor Winer, and he is her adviser and mentor.

In one project, Jun developed modifications for Professor Winer's regional model. Instead of using pollution exposures for a large area, "we can apply the model on a neighborhood scale," says Jun. The spatial resolution in her model, permitting assessments of areas as small as 100 to 200 meters, is unprecedented and critically important in quantifying the impacts of vehicle exhaust.

Jun's dissertation research drew on data from the USC Children's Health Study, which has followed more than 6,000 children in 12 Southern California communities since 1993. Whereas the initial work compared regional air pollution readings with aggregate results of lung function tests, Jun developed a model that could estimate the exposure of each child, based on pollution in the neighborhood around the child's home and school. Her work was a pioneering effort at creating a retrospective air pollutant exposure model.

Jun's models will provide helpful information to epidemiologists and other health officials who are studying the associations between air pollution and diseases like asthma or even brain tumors.

Careful attention to detail is a hallmark of her work. Instead of considering only outdoor pollution, for example, Jun accounted for the fact that "people spend most of their time indoors" and estimated that exposure. Instead of relying on children's estimates of the time it took to get to school—more or less than 15 minutes were the only available answers in the Children's Health Study— Jun calculated the actual mileage and corresponding commute time based on home and school addresses/locations, roadway networks, and driving speeds on different roadway types. "Children may not have a good idea of how much time passes," she says.

The study also asked children to estimate how much time they spent outdoors in the afternoon, using a multiple-choice scale from none to all. Jun found another database that had recorded 24-hour daily diaries of activities. Matching children in the two studies by age, gender, day type (for example, weekday), and the relative ranking of children's time spent outdoors and in vehicles, she devised more precise estimates of time spent outdoors.

Articles about her findings are awaiting updated information on the background pollution in various Southern California communities, so it can be added to the estimated pollution from vehicle exhaust. "We want to publish the best paper we can," she says.

Jun's path to UCLA began at home. "My Mom was the first one to plant this idea of becoming an environmental scientist," Jun says. "She told me that everyone has to breathe the air and drink the water, so helping to keep the air and water clean would be a great career—it benefits the whole world."

At Tsinghua University in Beijing, one of the best science and engineering schools in China, Jun studied environmental engineering. Her work with a group that developed a model simulating smog in urban areas piqued her interest in air pollution. Then, she went to Penn State University for a master's degree, also in environmental engineering.

Over the years, "I found out that I'm more interested in the basic science than in the engineering applications," Jun says. Before the engineering of solutions can begin, "you need to find out how much pollution is bad for health and set public policy." That's where her interest lies.

A Chancellor's Fellowship and the presence of her then-boyfriend now-husband in Los Angeles helped convince her to pursue a PhD at UCLA, but "most important, I found the most intriguing research projects here," she says. At an event for prospective graduate students, she met Professor Winer and found that "his project was the best fit for my interests," she says. In addition, "he's a very nice person to work with. He has very deep insight into his field and enormous enthusiasm for his students."

Jun hopes to find work in a government agency or research university, but she leans toward the latter because it will give her an opportunity to teach. She takes excellent credentials into her job search. During her three years at UCLA, she has "developed and applied a powerful new model of individual human exposure to key air pollutants," Professor Winer says. Her work is "one important response to the major public health challenge of protecting a highly vulnerable population, children, from the effects of air pollution."

Published in Fall 2003, Graduate Quarterly