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Public Radio's Environmental News Magazine (follow us on Google News)

On the Road That’s Travelled

Air Date: Week of

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Living, or working, near a freeway may be convenient, but a new study shows that it can also lead to health problems. Rose Hoban reports from Los Angeles.


CURWOOD: When you choose a home or a school, easy freeway access could be a big plus. But despite the convenience, new research indicates that spending a lot of time near a freeway may be worse for your health than previously thought. Rose Hoban reports.

HOBAN: Dominic DeFazio is a real estate agent in Pasadena, California. He specializes in high priced properties. Today, he is showing off one of the hottest developments in town, a tight cluster of gangster-era bungalows under old palm and pine trees.


DEFAZIO: At one time it was a campus as part of the Arroyo Hotel, which is just to the south of us.

HOBAN: Once these historic, old buildings are restored, DeFazio predicts they will sell for between $700,000 and a million dollars. There is a waiting list for buyers, and that’s even though…

DEFAZIO: Well, you can see the cars passing by, so I would imagine that we are less than 150 feet from the freeway.

HOBAN: A six-lane freeway. Realtors say the biggest concerns for homebuyers near freeways tend to be noise and dust. But researchers are learning more about freeway pollution beyond the dust that deposits on the windowsill. There are several components to pollution, starting with gases like carbon monoxide.

SAWYER: It’s toxic, but the one really great success story has been that the levels of carbon monoxide emissions are down by at least a factor of ten from the motor vehicle fleet.

HOBAN: Robert Sawyer is a UC Berkeley engineer who has spent the better part of 30 years studying air pollution. He says the last ten years have brought some success in reducing the polluting gases coming from cars. But there is a catch. As emissions from individual cars have decreased, the number of cars and the number of miles driven has increased.

And there is another part of the pollution equation – soot. There is more to soot than just the gritty, black, carbon-based smoke spewing from older trucks and cars. Soots come from many sources.

SAWYER: They come from such things as tire wear and brake wear, metal wear in the engine that sometimes will end up in the soot, and the road itself will wear. These wear-type particles tend to be larger, and, therefore, they fall out of the atmosphere quite rapidly.

HOBAN: These soots are about one-tenth the width of a human hair. Our respiratory systems are efficient at trapping these relatively big particles in the nose and throat, before they can get deep into the lungs and cause trouble. Still, these large particles are related to more emergency room visits and time lost from work and school.

The good news is that big particle levels have dropped off since they were regulated in 1997. But now, new technology is allowing scientists to discover another kind of particle, which they are calling “ultrafines.” These are so small that as many as 500 can fit into the width of a human hair.

HINDS: They are the smallest particles that you can make and still have them be particles. They are much smaller than bacteria.

HOBAN: William Hinds is a professor from the School of Public Health at UCLA, who has been studying ultrafines. He says they are made in engines that fire at high temperatures, so they are produced in both diesel and gasoline engines.

HINDS: Our findings indicate that the ultrafine pollution that comes from freeways is quite local, and it is confined to a relatively narrow region on and near the freeway.

HOBAN: How far away from the freeway do you begin to see things dropping off?

HINDS: You see them dropping off immediately at the edge of the freeway. It’s maybe 20 to 30 times higher on the freeway or right next to the freeway than it is more than a thousand feet away from the freeway.

HOBAN: Or about the length of three football fields. That’s much farther than big particles, which tend to drop out of the air right next to the freeway.

Hinds and other scientists in Southern California found that spending a lot of time living or playing close to freeways increases health risks, particularly asthma and other breathing problems. Other data show that student athletes playing on fields close to freeways had higher rates of asthma the more sports they played.

HINDS: We think that these very small particles are the most toxic of the particles, partly because of their chemical composition.

HOBAN: Scientists can’t tell exactly what is in them, but they think ultrafines include heavy metals from motor oils, which add to their toxicity. But what really makes ultrafines so dangerous is their size. They are small enough to get past the defenses of the respiratory system.

Another researcher, UC Irvine’s William Kleinman, said ultrafines can get through thin spaces in between cells, deep in the lung where oxygen exchange takes place.

KLEINMAN: And you can actually see these particles sneaking by the edges of the cells, which are normally very tight. And once you are down underneath that surface, there aren’t good mechanisms for cleaning them out. And they can stay there for a long time. If they are toxic, they can start doing their damage.

HOBAN: An article published in last month’s issue of the journal Environmental Health Perspectives suggests ultrafines could be triggering inflammation in lung cells, inflammation that can cause asthma. Over time, repeated exposure could be damaging to lung cells and even to cell processes in other parts of the body. All this new data is making regulators, legislators and scientists reconsider freeways as more than just noisy and dust-producing. And this may have far-reaching implications.

KLEINMAN: It would be better if you have to place a school near the freeway, at least put the athletic field on the far side. Allow some distance between the source of pollution and where the children are going to be playing and exercising.

HOBAN: A bill that recently passed the California Senate would restrict new school development within 500 feet of major roadways. And California’s Air Resources Board is discussing guidelines for land use adjacent to freeways. In the next few years, they will address the contentious issue of regulating new development next to freeways.

And as the public learns more about freeway air, it might change the equation for homebuyers who will have to weigh the health risks against a few minutes shaved off the commute.

For Living on Earth, I am Rose Hoban in Los Angeles.

[MUSIC: Goldenboy “Wild was the Night” Blue Swan Orchestra b-girl records (2002)]

CURWOOD: Coming up: the Senate votes to revitalize the nuclear power industry.

You’re listening to NPR’s Living on Earth.

[MUSIC: Snares & Kites “Chloroform Memory” Tricks of Trapping Inbetweens Records (1999)]



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