Luchtvervuiling nog gevaarlijker voor hart dan voor longen.

Long-term exposure to fine particles -- so-called particulate matter -- in polluted air is more likely to cause death from cardiovascular disease than from respiratory conditions, researchers reported Monday.

In a study looking at pollution effects in U.S. metropolitan areas, 45.1 percent of deaths were attributable to cardiovascular disease, whereas only 8.2 percent were related to respiratory diseases.

"While we know that air pollution is not the dominant cause of atherosclerotic diseases (hardening of the arteries), these results are consistent with findings that air pollution provokes inflammation, accelerates atherosclerosis, and alters cardiac function," lead author Dr. C. Arden Pope III, from Brigham Young University in Provo, Utah, said in a statement.

The new findings, published in the American Heart Association's journal Circulation, are based on an analysis of data on deaths classified according to specific cause, combined with air pollution data from 116 US cities. Data on 500,000 subjects were included in the analysis.

During the 16- year study period, 22.5 percent of the subjects died, the researchers note. Further analysis confirmed a direct link between long-term particulate matter exposure and cause- specific mortality.

For each unit rise in particulate matter, the risk of death from cardiovascular disease plus diabetes rose by 12 percent.

Respiratory disease deaths were not consistently associated with particulate matter exposure, the authors note. Among people who had never smoked, such exposure was positively linked to mortality from pneumonia and influenza. Interestingly, however, chronic obstructive lung disease (COPD) and related deaths seemed to decrease as levels of particulate matter rose.

Smoking was found to be a stronger risk factor than air pollution for deaths from cardiovascular and respiratory diseases, the researchers found. However, as expected, the two factors often work together to produce a larger increase in risk.

"There is no question that active cigarette smoking is a much, much larger risk factor than air pollution," Pope said. "We don't know precisely how the two relate, but there is some evidence in our study that the mechanisms are similar or complementary."

Although "non-smokers exposed to high levels of air pollution will probably not die of COPD," an editorial points out, "they may develop a higher than normal risk of death from pneumonia or influenza."

SOURCE: Circulation, December 2003.  

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