By Tabitha Laffernis, March 10, 2014
Researchers have found the increase exposure to nitrogen oxide -
commonly found in traffic air pollution - change the structure of the
human heart, leading to a higher incidence of heart failure in
previously healthy patients.
Traffic air pollution has been linked to poor health in the past -
with wheezing, coughing, and watery eyes just the tip of the iceberg.
Later studies have also established a relationship between pollution and
a host of heart problems, including left ventricular hypertrophy and
heart failure, among others. However, a new study, from the University
of Washington's Medical Center in Seattle, has now found that air
pollution emitted from traffic sources also changes the structure of the
heart's right ventricle - further increasing the risk of heart failure
for residents' of pollution-dense areas.
"Although the link between traffic-related air pollution and left
ventricular hypertrophy, heart failure, and cardiovascular death is
established, the effects of traffic-related air pollution on the right
ventricle have not been well studied," said the
study's lead author Peter Leary, MD, MS, of the UW Medical Center in a
press release. "Using exposure to nitrogen dioxide as a surrogate for
exposure to traffic-related air pollution, we were able to demonstrate
for the first time that higher levels of exposure were associated with
greater right ventricular mass and larger right ventricular
end-diastolic volume. Greater right ventricular mass is also associated
with increased risk for heart failure and cardiovascular death."
The study observed the health patterns of 3,896 individuals who
participated in the Multi-Ethnic Study of Atherosclerosis, each of whom
had no prior history of cardiac disruption or disease. All of the test
subjects had previously undertaken magnetic resonance imaging (MRI)
scans, with authors observing their levels of exposure to pollutant
nitrogen oxide in the year leading up to the scan.
On average, the study found that a higher incidence of exposure to
nitrogen oxide coincided with a five percent increase (around one gram)
in right ventricular mass and a three percent increase (4.1 mL) in
right ventricular end-diastolic volume. The researchers combed through a
range of differentiating factors that could have skewed the data before
confirming their findings, including variations in lung disease,
socioeconomic standing, inflammation, and left ventricular mass and
"The morphologic changes in the right ventricle of the heart that we
found with increased exposure to nitrogen dioxide add to the body of
evidence supporting a connection between traffic-related air pollution
and cardiovascular disease," said Leary. "The many adverse effects of
air pollution on human health support continued efforts to reduce this
It should be noted, however, that while increased exposure to
nitrogen oxide led to a notable change in the heart's structure, the
findings have not definitively been linked to traffic air pollution.
However, the researchers are confident that these recent findings are
aligned with previous studies on the matter, and serve to strengthen
beliefs that traffic air pollution is detrimental to cardiovascular
The study was published in the American Journal of Respiratory and Critical Care Medicine.