Roadways: Air Pollution & Health

Roadways: Air Pollution & Health

Are Roadways Harming Your Health?

Like many cities, Ann Arbor is surrounded by freeways—a fact that may affect the health of some Ann Arborites, says Sara Adar, a research assistant professor of epidemiology who studies air pollution. Adar and others have found that people who live within 50 to 100 meters of a large roadway have a higher risk of cardiovascular and respiratory disease than those who live 150 or more meters away.

"So if you live in close proximity to a highway, you might choose to keep your windows shut more often and use air conditioning, which can dramatically reduce the levels of certain pollutants," she says. "Or you might put in a filtration system."

Particulate matter from cars and trucks—especially diesel engines—has been linked to cardiovascular disease and atherosclerosis and to the general depreciation of human health over time. Adar has found, for example, that in Los Angeles, California, which is known for its traffic congestion, residents have more highly constricted blood vessels—an indicator of cardiovascular disease.

But it's not just proximity to roadways that counts—traffic jams themselves seem to matter. In a study of freeway commuters in St. Louis, Missouri, Adar found that seniors' heart rhythms changed within five minutes of being exposed to motor-vehicle exhaust. "You could really see it, and you could see it right away," she says. "Being in traffic prompted a stronger, more negative response." Adar has also looked at the effect of diesel emissions on children in Seattle who ride schoolbuses, and she has begun studying possible connections between mortality rates and traffic jams in neighborhoods near major roadways. Intriguingly, she notes, mortality rates seem to rise during periods of heavy traffic congestion. She is also interested in noise, which has been linked to cardiovascular disease through its effect on stress. "Can you tease apart air pollution and noise?" she asks.

Some of Adar's research is closely related to the longitudinal Multi-Ethnic Study of Atherosclerosis (MESA) Neighborhood study directed by SPH epidemiologist Ana Diez Roux.

Beyond its obvious contributions to our understanding of health and the built environment, Adar's research has important policy implications. "If a community is going to build a new daycare center or school or senior home," she says, "proximity to roadways should be a consideration."

To learn more:


  • The World Health Organization estimates that nearly 800,000 lives are lost annually around the world due to exposures to air pollution; in the U.S., the number is likely around 24,000 per year
  • According to WHO, chronic exposures to air pollution from vehicles in Austria, France, and Switzerland are responsible for 21,000 premature deaths per year from respiratory or heart diseases, exceeding the number of annual deaths from motor vehicle accidents in the three countries
  • Motor vehicles account for approximately 25 percent of all particulate emissions to the air in the U.S.; vehicles also contribute approximately one-third of all of our greenhouse gas emissions
  • Concentrations of air pollutants are highest between 50 and 100 meters from major roadways; beyond 150 meters, concentrations of air pollutants plummet rapidly to background levels
  • Research has shown a two-fold increase risk of a heart attack after time spent in traffic