Thursday, July 12, 2007
Soot - an Invisible Hazard
Given what can be in the air, “people who exercise outdoors should probably be more worried” than many are, said Morton Lippmann, a professor of environmental medicine at the New York University School of Medicine.
And there are long-term consequences. A study that used the mass of data included in the Women’s Health Initiative found that women who lived in communities with relatively high levels of air pollution in the forms of tiny particles — a k a soot — were far more likely to die because of heart attacks than women who lived in cleaner air. Results were published in February in The New England Journal of Medicine.
“Fine particulates are definitely something to worry about,” said Dr. Rundell, especially for athletes, who, in the process of exerting themselves, “can take in very elevated doses.”
That may go against conventional wisdom. Most people, when they think of air pollution, think first of ozone, a ground-level gas created when sunlight reacts with pollutants emitted by cars and factories. Ground-level ozone, popularly known (and loathed) as smog, has long been recognized as a threat to cardiovascular health.
“Ozone over the long term causes what is similar to a premature aging of the lungs,” said Michelle Bell, an assistant professor of environmental health at the Yale School of Forestry and Environmental Studies.
But today most experts agree that, as Dr. Lippmann said, the “greatest overall public health impact” of air pollution comes from fine particulates, which can be seen only with an electron microscope.
They are ubiquitous. Cars, trucks, and diesel buses — the main culprits in the creation of particle pollution — spew untold millions of the microscopic pollutants into the air daily. Exercisers should take precautions against particles, experts said, by not exerting themselves near traffic, or, if they must use a path next to a highway, staying a few hundred yards away from vehicles.
Particles can sail past nasal hairs, the body’s first line of defense, and settle deep in athletes’ lungs. Some remain there, causing irritation and inflammation. Others, so tiny they can bypass various bodily defenses, migrate into the bloodstream. “Blood vessels do not like those particulates,” said David Newby, a cardiology professor at the University of Edinburgh.
There seems little doubt that the particles do promote cardiac disease — in athletes and others. Dr. Lippmann has found that mice exposed to large doses of the particulates develop atherosclerosis, or narrowed, plaque-riddled arteries. Other studies have suggested similar effects probably occur in the arteries of people, although the evidence is not definitive. Based on experiments to date, though, a 2004 American Heart Association scientific statement concluded that “air pollution may accelerate the development of coronary atherosclerosis.”
Dr. Lippmann is quick to point out that any health damage from air pollution depends on the size of the dose. “The risks from one run would be negligible,” he said. But the cumulative risk — over months or years of panting through workouts on hazy days — “would not be.”
In the calculus of health concerns, “Breathing air pollution is not nearly as bad as smoking,” Dr. Lippmann said.
“The bottom line is that running and cycling are healthy and, over all, good for the heart,” Dr. Newby said. With proper care, he said, outdoor exercise does not have to be harmful — and, done en masse, could even ease pollution.
“I ride my bike back and forth to work every day,” he said. “If everyone else did that, too, we wouldn’t be having this problem at all, would we?”
SOURCE
And there are long-term consequences. A study that used the mass of data included in the Women’s Health Initiative found that women who lived in communities with relatively high levels of air pollution in the forms of tiny particles — a k a soot — were far more likely to die because of heart attacks than women who lived in cleaner air. Results were published in February in The New England Journal of Medicine.
“Fine particulates are definitely something to worry about,” said Dr. Rundell, especially for athletes, who, in the process of exerting themselves, “can take in very elevated doses.”
That may go against conventional wisdom. Most people, when they think of air pollution, think first of ozone, a ground-level gas created when sunlight reacts with pollutants emitted by cars and factories. Ground-level ozone, popularly known (and loathed) as smog, has long been recognized as a threat to cardiovascular health.
“Ozone over the long term causes what is similar to a premature aging of the lungs,” said Michelle Bell, an assistant professor of environmental health at the Yale School of Forestry and Environmental Studies.
But today most experts agree that, as Dr. Lippmann said, the “greatest overall public health impact” of air pollution comes from fine particulates, which can be seen only with an electron microscope.
They are ubiquitous. Cars, trucks, and diesel buses — the main culprits in the creation of particle pollution — spew untold millions of the microscopic pollutants into the air daily. Exercisers should take precautions against particles, experts said, by not exerting themselves near traffic, or, if they must use a path next to a highway, staying a few hundred yards away from vehicles.
Particles can sail past nasal hairs, the body’s first line of defense, and settle deep in athletes’ lungs. Some remain there, causing irritation and inflammation. Others, so tiny they can bypass various bodily defenses, migrate into the bloodstream. “Blood vessels do not like those particulates,” said David Newby, a cardiology professor at the University of Edinburgh.
There seems little doubt that the particles do promote cardiac disease — in athletes and others. Dr. Lippmann has found that mice exposed to large doses of the particulates develop atherosclerosis, or narrowed, plaque-riddled arteries. Other studies have suggested similar effects probably occur in the arteries of people, although the evidence is not definitive. Based on experiments to date, though, a 2004 American Heart Association scientific statement concluded that “air pollution may accelerate the development of coronary atherosclerosis.”
Dr. Lippmann is quick to point out that any health damage from air pollution depends on the size of the dose. “The risks from one run would be negligible,” he said. But the cumulative risk — over months or years of panting through workouts on hazy days — “would not be.”
In the calculus of health concerns, “Breathing air pollution is not nearly as bad as smoking,” Dr. Lippmann said.
“The bottom line is that running and cycling are healthy and, over all, good for the heart,” Dr. Newby said. With proper care, he said, outdoor exercise does not have to be harmful — and, done en masse, could even ease pollution.
“I ride my bike back and forth to work every day,” he said. “If everyone else did that, too, we wouldn’t be having this problem at all, would we?”
SOURCE
Labels: exercise, lungs, pollution
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