Something in the air
Lungs probably aren’t the only parts of your body that suffer from poor air quality. Your heart, too, may be damaged.
For several years doctors have noticed that cardiovascular disease deaths and hospital admissions increase when air quality is poor. They and other experts suspect that certain pollution components -- called ultra-fine particles -- may be the culprit.
A new federally funded study will attempt to prove their theory.
Researchers will monitor ultra-fine particles in air pollution on various days. Ultra-fine particles are produced primarily by engine combustion and are most concentrated in areas with heavy traffic and fresh tailpipe exhaust. (As they disperse, ultra-fine particles sometimes clump together to become large particles.) The researchers also will conduct medical tests on elderly people with existing heart disease on the same days.
Laboratory research has shown that ultra-fine particles are small enough to get into the bloodstream and, once there, can cause inflammation in cells.
“These particles gain access into the tissue of the lungs; then they are able to penetrate into the cells themselves,” says Dr. Ralph Delfino, an epidemiologist at UC Irvine, who is helping to conduct the study. “In addition, they can go in through the blood vessel walls and get into the bloodstream.”
After they reach the heart, the particles are thought to cause a stress reaction in cells, producing inflammation that contributes to heart disease, Delfino says. The particles also may cause blood clots.
The study, sponsored by the National Institutes of Health, will include 72 participants, age 65 and older, who have heart disease and who live near freeways and other heavy traffic areas in Orange, Los Angeles and Riverside counties. Because they already have the disease, changes in their condition caused by air pollution should be easier to detect.
They’ll be monitored for blood pressure, abnormal heartbeat patterns and changes in blood flow to the heart. To get the most accurate readings, the participants will wear monitoring devices that take measurements around-the-clock. Researchers also will take blood tests, looking for indications of the inflammation associated with heart disease.
Although the study can’t prove conclusively that ultra-fine particles contribute to heart disease, it should be able to determine whether there’s a correlation between high levels of the pollutants and cardiovascular health.
This type of study, known as epidemiology, should be considered when government officials enact air quality rules, Delfino says. Presently, air quality regulations focus more on measurements of gases in the air, such as ozone, and the concentration of larger particles.
“When the regulators get together to decide what to do, they have to take into consideration all kinds of research, including epidemiology,” he says. “It tells you the impact of these pollutants on public health. You can study rats until you’re blue in the face, but it doesn’t tell you the effects on people.”
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Unregulated emissions are hard to monitor
About ultra-fine particles
Ultra-fine particles are produced primarily by engine combustion and, at a size of less than 100 nanometers, are easily absorbed into the bloodstream and cells.
Local and federal government agencies do not regulate emissions of these particles. That could be because scientists know less about their effect on human health than they do about the effects of other components of air pollution, such as larger particles and gases such as carbon monoxide and ozone, says Dr. Ralph Delfino.
Ultra-fine particles also would be harder to monitor and regulate because their concentration varies widely within an urban area. Larger particles tend to be more uniformly distributed.
