Few Americans have ever heard of Joel Schwartz, or have any idea what he's done for them lately. It was back in 1991 that Schwartz, then with the U.S. Environmental Protection Agency (EPA), gained recognition as the first federal employee to receive the MacArthur Award, a no-strings-attached, $275,000 "genius grant." The award honored Schwartz for a rare achievement in public health: identifying an environmental exposure that threatened millions--lead in gasoline--and supplying enough evidence to ban it. Hearing of Schwartz's award, EPA Administrator William Reilly said: "Every time you fill up your car with gasoline, you can think of Joel Schwartz."

This story is worth recounting because it illustrates a key facet of Schwartz's prolific career: He is both a scientist and a policy catalyst whose work has spawned sweeping regulatory changes concerning not just lead, but also minute particles in air pollution that kill at least 100,000 people every year in the United States alone. Schwartz was among the first to link elevated death rates to particulates of sulfur from coal-burning power plants and black carbon from motor-vehicle exhaust. Today, as a professor of environmental epidemiology at the Harvard School of Public Health (he won tenure last spring), he continues to drive the science that has tightened federal clean-air standards and improved compliance. Having shown a link between particulates and heart attacks, he's now working to explain the connection.

"We're looking at changes in electrocardiogram patterns, inflammatory markers in blood, and changes in arterial function," Schwartz says, adding that particulates may injure and kill by inciting inflammation. In June, Schwartz published a study showing that on days when air pollution is high, people with diabetes are at especially elevated risk for cardiovascular problems--atherosclerosis, stroke, heart attack, heart failure, even death. That vulnerability, he showed, stems from their arteries' inability to expand fully in response to the body's demands for more oxygenated blood.


This graph from a 1984 EPA cost/benefit analysis by Joel Schwartz and others shows a striking correlation between sales of leaded gasoline and blood levels of lead in children.


Schwartz is known for his inventive use of time-series analyses to plumb associations between environmental pollutants and ill health. This method, borrowed from economics, looks at changes in one variable relative to another.

Industry has spent enormous sums trying to discredit his conclusions, but he consistently counters skeptics with solid data. "The brilliant thing about Joel is that he looks around and asks, 'Is there data already out there that I can acquire inexpensively, manipulate, and use?'" says Joseph Brain, Cecil K. and Philip Drinker Professor and chair of the Department of Environmental Health at HSPH. Schwartz's genius, Brain says, lies in mining freely available data collected by municipalities, hospitals, and local businesses. Because his datasets are large, his conclusions are statistically powerful.

Schwartz likes to emphasize what he calls "the public health part" of his research. His work has engaged collaborators in Australia, Brazil, Greece, Korea, Switzerland, and the Netherlands, and is shaping regulations in Egypt, India, Israel, and Europe, as well as the U.S.

"This isn't just pure science, it's science for public policy," Schwartz says. "If you're not willing to rub people's noses in the fact that you've identified a problem, and that something needs to be done about it, then have you improved public health? You need to be willing to take the next step--and take a lot of criticism of your findings from people who have a monetary interest in their not being true."

Getting the Lead Out
An epidemiologist, Schwartz is self-taught; he has no formal training in his field. While finishing up a PhD in theoretical physics at Brandeis University, he began working for Colorado Representative Timothy Wirth as a legislative assistant for energy and the environment. That experience helped him land a job in 1979 with the EPA's policy office. At the time, the EPA was under fire from Department of Energy (DOE) officials seeking to relax environmental standards in order to ease the impact of rising oil prices and relieve oil shortages. Schwartz handily fended off an assault on the EPA's clean-air standards by showing that the department could accomplish its goals more economically by easing its own regulations governing the use of costly technologies for extracting oil and gas. During a pivotal meeting at the White House, DOE leaders decided to take Schwartz's advice.

Following Ronald Reagan's election in 1981, the new administration asked the EPA to eliminate restrictions on the amount of lead that could be added to gasoline. That move would have enabled oil refiners to put the right amount of octane in gas at significantly lower cost. Schwartz calculated the potential savings to the oil industry--$100 million by his estimation--but extended his analysis to consider the consequences for health.

What he found was startling: In parts of the country where leaded-gas sales had fallen, children's blood lead levels had also fallen; in fact, the relationship was almost perfectly correlated (see graph on page 15). Working with his wife, EPA scientist Ronnie Levin, he then estimated what the national impact on children's IQ would be should the content of lead in gas be allowed to increase. And in a stroke of innovation, he used earnings data that linked IQ to productivity to calculate long-term economic losses from lead-induced IQ declines. By this analysis, a scale-back of the leaded-gas standard would cost several billion dollars annually.

In view of these findings, the EPA did an about-face and tightened the lead standard. "We proposed to dramatically cut back on leaded gas in February of 1984, and exactly one year later, the EPA issued the final rule," Schwartz recalls, adding that energy companies quit the leaded-gas market as demand crashed. "Compared to normal EPA rule-making, this was the speed of light!"

Battle Over Particulates
Schwartz jokes that his EPA colleagues said to him, "'You know, you've been too successful--you've gotten rid of lead in gas. Now go do something else.' So, I started looking at air pollution," he says.

A 1960s health study of California nurses piqued his curiosity. The data showed that respiratory symptoms from environmental tobacco smoke lacked a threshold--in other words, even the smallest exposure had a negative effect on health. The data shaped his views on air pollution and confirmed his suspicion that particles--not ozone, sulfur dioxide, or other gases--were the root cause of its most insidious effects. That notion was bolstered by his reassessment of a 14-year study of air pollution and health in London.

"On any given day when there were more particulates in the air, more people died," Schwartz says of his analysis. His assumptions, roundly criticized by industry, were upheld by the EPA, which in 1987 issued a standard restricting daily and annual averages for particles to a diameter of 10 microns or less, designated as PM10--or about one-tenth the width of a human hair.

Schwartz, however, thought the standard was weak; in his view, the lack of a threshold justified even tougher limits. So he spent the next five years cranking out studies in different parts of the U.S. that all showed the same thing: as the levels of airborne particles climbed, more people died.

But this time, the EPA was less receptive. Officials rejected his calls for more stringent standards, and Schwartz began to feel isolated and harassed within the agency. Fortunately, the $275,000 MacArthur Award gave him some financial flexibility. In 1994, he accepted the post of associate professor at HSPH.

At the School, Schwartz has continued his relentless push to drive air-particulate levels down. He played a silent but pivotal role in a lawsuit brought by the American Lung Association in 1992 against the EPA demanding that the PM10 standard be reviewed in light of emerging health-effects data, as the law requires every five years. Meanwhile, industries most affected by the standard, mainly energy companies and automakers, spent $100 million in a counter-offensive.

"There were all these TV ads in the Midwest saying, 'You're going to lose your job if the EPA does this wacky thing,' " he says. "And industry hired lots of consultants to orchestrate this huge campaign to criticize our studies on a scientific front, and lobby against the standard on a political front."

It wasn't until 1997 that the EPA set stricter clean-air standards, this time targeting particles of PM2.5, 2.5 microns or less. Opponents challenged the standard all the way to the U.S. Supreme Court, where in 2001 it was upheld.

Staying the Course
For Schwartz, reinforcing the science behind PM2.5 has practically been a full-time job. "We had to continue proving the case on particles in order to get anything done about it," he says, with a grin that belies the focused intensity of his efforts.

The story continues to evolve, zeroing in on particles' more subtle effects. Schwartz has shown, for example, that particles increase childhood hospital admissions for pneumonia, acute bronchitis, and asthma.

Schwartz's anti-lead crusade isn't over, either. Today, with Professor of Occupational and Environmental Medicine Howard Hu and colleagues, he studies how lifetime accumulations of lead influence cognitive function in elderly men. Lead sequesters in bone, which thins gradually as people age, releasing the neuro-toxic metal to the bloodstream. Recent studies by the HSPH team show that scores on tests for short-term memory, pattern recognition, and other basic mental abilities decline as bone-lead concentrations rise. Also in the publishing pipeline are studies to which the researchers have lent expertise suggesting that common variations in certain genes heighten some people's susceptibility to lead, possibly because they enhance the body's absorption of the metal.

As if lead and air pollution weren't enough to keep him busy, Schwartz has added drinking water to his list. "We're seeing more serious effects from water disinfectant by-products such as trihalomethanes, which derive from chlorine," he says. "These chemicals cause DNA mutations that may be linked to more cancers than we previously anticipated, and also to lower birth weight in children--at doses below current EPA standards. But we're also seeing imperfect disinfection, which gives you giardia and other diseases caused by waterborne microbes.

"The water industry likes to say everything is perfect," he says. "Nothing is ever perfect."

Meanwhile, Schwartz continues to seek out ways to sway air-quality policy. Opportunities lie in gauging the relative toxicities of particles from different sources, such as diesel engines and wood-burning stoves. More information will help regulators set priorities, he says.

"Having generated a fair amount of policy change, I think it's important that I look around for under-appreciated problems," Schwartz says. "If we can identify new problems that affect people's health and do something about them, that's a very good thing."

Charlie Schmidt writes about science, health, and the environment for Technology Review, Environmental Health Perspectives, and the Journal of the National Cancer Institute.


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