UW Center for Clean Air Research

Studying Roadway Pollution

Sverre Vedal

Sverre Vedal, director of the new UW Center for Clean Air Research
Photo: Sarah Fish

Drivers, bikers, and pedestrians on major roadways are exposed to a variable and complex mix of pollutants from vehicle emissions and road-surface wear. The new University of Washington Center for Clear Air Research (UW CCAR) will study the impacts of these pollutants on human health. "There has been a concern that we've been ignoring exposures people face while they're commuting," said Professor Sverre Vedal, center director.

The center is part of the US Environmental Protection Agency's (EPA) large-scale effort to study complex mixtures of air pollutants, especially their effects on vulnerable populations, including children, the elderly, and people with chronic cardiac or respiratory disease. Three other CCARs were funded at Harvard University, Michigan State University, and one held jointly by Emory University and Georgia Institute of Technology. Each center will receive about $8 million over five years.

Previous emissions research focused on single pollutants, such as ozone, sulfur dioxide, or particulate matter, microscopic particles of soot and smoke generated by internal combustion engines. However, vehicles also emit numerous other pollutants, including volatile organic compounds that evaporate from fuel, and very little is known about how these compounds interact to affect health. "It's the mix that's important, not necessarily a single compound in that mix," said Vedal.

A mix of disciplines is also crucial to conducting this multifaceted research. The UW CCAR team includes epidemiologists, atmospheric scientists, chemical engineers, toxicologists, physicians, and biostatisticians. Partnering institutions include Washington State University; the Lovelace Respiratory Research Institute in Albuquerque, New Mexico; and University of New Mexico.

For more than 60 years, department researchers have investigated the impact of air pollution on the environment and human and animal health. They have shown that exposure to air pollution contributes to heart disease and respiratory disease, such as asthma in children. Research indicates that people living in close proximity to major roadways are at increased risk for changes in the heart that lead to cardiac disease, and that inhaling emissions can increase blood pressure, perhaps by causing inflammation in the heart and blood vessels.

Past research has also shown that impacts of exposure depend on distance from a major roadway. "Fresh vehicle emissions are rich in ultra-fine particles," said Vedal. Particles this small lodge deep in the lungs, and can cross into the blood stream, causing systemic damage as they circulate through the body. There are fewer ultra-fine particles as the distance from a roadway increases because as particles age, they collect more organic compounds and increase in size. "Our 'straw man' hypothesis is that aging decreases toxicity of these pollutants," explained Vedal.

Center researchers will collect detailed data on roadway pollutants and ways the mix evolves over time. They will also study health impacts of exposure at the clinical and molecular levels.

Two other centers in the department are providing crucial resources for this work, the Multi-Ethnic Study of Atherosclerosis and Air Pollution (MESA Air) and Disease Investigation through Specialized Clinically Oriented Ventures in Environmental Research (DISCOVER), both directed by Professor Joel Kaufman, also a UW CCAR researcher. These resources include an exposure chamber to study the physiological responses of people and animals to vehicle emissions and the ability to access participants from the MESA study, which includes more than 6,000 men and women in six states. "MESA is a unique cohort that has collected a vast amount of data on cardiovascular disease, including imaging of subclinical measures, such as thickness of arterial walls and calcium deposits in arteries," said Vedal.

Other lead UW CCAR researchers include Professors Timothy Larson, Michael Rosenfeld, Lianne Sheppard, and Michael Yost, and Associate Professor Christopher Simpson.

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