New Insights Into Traffic, Air-Pollution Risks, and Atherosclerosis

Shelley Wood

April 23, 2013

ROME — Investigators for the Heinz Nixdorf RECALL study have dug deeper into their analysis looking at the link between atherosclerosis on computed tomography and proximity to heavy traffic and its associated pollution[1].

The new results, presented last week at EuroPrevent 2013 , build on those published in Circulation in 2007, as reported by heartwire . In that earlier analysis, researchers found that living close to heavy traffic was associated with higher degrees of coronary calcification on computed tomography. They also documented an association between fine particulate matter 2.5 µm in diameter (PM2.5) and coronary artery calcium.

The Heinz Nixdorf Recall study was launched in the early 2000s, conducting electron-beam computed-tomography scans in almost 5000 subjects from three German towns, all of whom were at least 45 years old and free of cardiovascular disease.

In their new analysis, Dr Hagen Kälsch (West-German Heart Center Essen, Germany) looked at thoracic aortic calcification (TAC) instead of CAD, "so looking at extracardiac atherosclerosis as opposed to coronary atherosclerosis," he explained. They also looked at TAC in relation to three parameters:

  • Whether particulate air pollution of different sizes is associated with different aortic atherosclerosis patterns.

  • Whether traffic noise had any influence on TAC.

  • Whether proximity to traffic noise was associated with atherosclerosis as seen on TAC.

A total of 4238 patients for whom the traffic-proximity data were available were included in the analysis; all had undergone coronary calcium CT scans of the thoracic aorta at study entry.

According to new data presented here, proximity to major roads and presence of PM2.5 were both associated with increasing degrees of aortic calcification. With every 2.4-µg/m3 increase in particulate volume, TAC increased by 20.7%. Likewise, for every 100-m proximity to heavy traffic, calcification increased by 10%. Finally, a 5-dB increase in nighttime noise was associated with a 3.9% increase in TAC.

Importantly, all three traffic-related effects appeared to act independently.

"In the past there have been many studies that already pointed out that there might be an association [between air pollution and heart disease] and also traffic noise and atherosclerosis burden," he said. "But until now, one wasn't sure what parameters had the main influence of the already-observed observation. Therefore, we analyzed these parameters simultaneously, and we found that all three parameters had involvement, but also independent of each other. So even when your residence is very far from a road with high traffic, where noise levels are low, but you still have high air pollution, your cardiac risk is elevated."

Investigators have since performed follow-up cardiac CT and have data on atherosclerosis progression that will be the topic of a subsequent paper. "The next step will be first of all to take an assessment of these associations from air pollution without outcome data--MI, all-cause mortality, and stroke--and the second thing is the progression data of calcification in the thoracic and coronary vessels."

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