The decline in highway traffic that was brought on by the spike in gas prices may be a boon to heart health.
That's because automobile emissions are among a long list of risk factors for heart disease and stroke.
"There's a very coherent and consistent body of data that links particulate air pollution with cardiovascular disease and premature death," said Dr Ted Schettler, science director of the Science and Environmental Health Network, an environmental and public health advocacy group.
Among the latest evidence: a German study published recently in Circulation: Journal of the American Heart Association, which found that people who live near heavy traffic are more likely to develop atherosclerosis, or hardening of the arteries, which can boost the risk of heart disease.
Atherosclerosis is a progressive disease that begins with damage to the lining of the arteries. Over time, the arteries accumulate plaque, a combination of fat, cholesterol, calcium and other substances. This causes the arteries to become rigid and narrow, impeding the flow of oxygen-rich blood to the heart and other parts of the body. This can lead to a heart attack, stroke or even death, according to the US National Heart, Lung, and Blood Institute.
More exposure, greater risk
In 2004, the American Heart Association issued its first official statement on air pollution and cardiovascular disease. In reviewing the scientific evidence, an expert panel concluded that short-term exposure to elevated particulate matter, which includes motor vehicle emissions, "significantly contributes to increased acute cardiovascular mortality, particularly in certain at-risk subsets of the population."
The panel further noted that prolonged exposure to elevated levels of air pollution reduced overall life expectancy "on the order of a few years."
To assess the impact of long-term residential traffic exposure on the heart, Dr Barbara Hoffmann, head of the unit of environmental epidemiology at the University of Duisburg-Essen, and colleagues used "electron-beam computed tomography" to measure calcium build-up in the arteries.
Compared with people who lived more than 200m from major traffic, the risk of coronary artery calcification was 63% higher for people living within 50m of heavy traffic, and 34% higher for those who were between 51m and 100m away. The risk was 8% higher for those living 100m to 200m away.
Same effect as ageing
Hoffmann compares the damage wrought by traffic fumes to the effects of ageing. "Living within 100m of a major road compared to people living further away amounts to a similar difference in coronary calcification as six months of ageing," she said.
Her team is currently examining all study participants again to determine whether those living close to heavy traffic have suffered a greater increase in coronary calcification during the past five years.
So what can individuals do, short of moving away from heavily travelled roads, to stave off cardiovascular disease?
The best thing is focus on modifiable factors, such as keeping blood pressure and diabetes in check, lowering cholesterol, increasing physical activity and quitting smoking, Hoffmann said.
Reducing air pollution is a larger challenge.
In big US cities, state and local agencies are required to report the Air Quality Index - a measure of how pristine or polluted the air is - each day, says AirNow, a federal government Web site on air quality. Depending on the level of concern, people with heart or lung disease, older adults and children may be advised to remain indoors.
"That's just a Band-Aid on a public health problem," Schettler said. "Do we want people who have early cardiovascular disease to have to avoid breathing air outside, or do we want to clean up the air?" - (Karen Pallarito/HealthDay News)
Air pollution bad for asthma
Car exhaust chokes sperm