Exposure to diesel exhaust is part of our everyday lives. We encounter diesel-powered vehicles, and the air pollution they create, each day. This occurs in our neighborhoods where diesel-powered vehicles make deliveries or pick up trash, or when we drive behind them during our daily rounds to the store or travel on a highway. Most often, Americans are exposed to diesel pollution on their way to and from work or school, whether commuting via a car, riding on diesel buses and trains, or on foot or bike near a busy thoroughfare.

In thousands of medical studies, scientists have documented serious adverse health impacts from the air pollutants resulting from diesel exhaust. Our own studies at New York University have linked diesel pollution exposures to higher incidences of asthma in New York City communities. One of the most dangerous of these diesel emissions is carbonaceous particulate matter, or fine particle soot. Diesel particles are very tiny in comparison to many other atmospheric particles. They are so small, in fact, that they can even penetrate from the lungs into the bloodstream, carrying with them other toxic substances. Some health researchers have estimated that such fine particles are responsible for shortening the lives of at least 70,000 Americans each year, and studies have also associated this pollution with a host of other serious adverse health impacts, such as asthma attacks. Scientists now even have evidence that these very tiny particles may disrupt normal heart rhythms and cause inflammation leading to cardiovascular problems, such as heart attacks and stroke.

Given the potentially severe health dangers posed by diesel exhaust, it is important to ask: When are we most exposed to these deadly particles? Findings in published, peer-reviewed health research estimate that, although we spend only about six percent of our day commuting to and from work, over half of our exposure to these particles may occur during that travel time.

The Clean Air Task Force (CATF), using the same type of monitoring instruments and scientific methodologies presently used by health researchers at major universities, has investigated the levels of diesel particles during commutes in several cities. These investigators measured pollutant levels during commutes by car, transit bus, commuter train, ferry, and while walking. They found that regardless of how you get to work, there is no escape from exposure to diesel exhaust, and that pollution levels measured inside cars, buses, and trains during commutes were many times greater than levels in the outdoor air in these cities at that same time. The combined weight of scientific evidence from this new CATF diesel exposure study along with the existing medical studies supports the conclusion that exposure to diesel exhaust during commutes poses a serious public health risk that needs to be addressed.

Solving the problem will require political will. But as the CATF investigation also helps illustrate, the good news is that cleaner fuels and emissions control technologies that can reduce the emissions of this pollution by up to 90 percent are here today. We need to make retrofitting the diesel engines on the road today with these highly effective emissions controls a public health priority, so that we can all breathe easier.

George D. Thurston, Sc.D.
New York University School of Medicine