Home' Trinidad and Tobago Guardian : April 29th 2013 Contents B28
body & soul
Guardian www.guardian.co.tt Monday, April 29, 2013
These studies point to potentially harmful exposures that could
trigger damaging physiological changes. They are particularly
concerning since many people can't avoid exposure to pollutants,
particularly from cars. PHOTO COURTESY MERCOLA.COM
Smog and car exhaust can take a toll on the
heart, and the latest research explores how.
Previous studies have shown an association between
badly polluted air and a heightened risk of heart
attack or stroke. And researchers have started to
investigate how pollutants could exert such harm.
Some have documented the increased inflammation
that pollution can trigger, as well as changes in blood
pressure and the activity of clotting factors in the
blood that could promote heart disease.
The latest research, published in the journal PLOS
Medicine, found that exposure to air pollution may
increase heart attacks and strokes by accelerating the
process of atherosclerosis.
Researchers from the University of Michigan School
of Public Health and the University of Washington
followed 5,362 people between the ages of 45 and 84
from six regions in the US: Baltimore, Maryland,
Forsyth County, North Carolina, Los Angeles County,
California, Northern Manhattan and Southern Bronx,
New York and St Paul, Minnesota.
The participants were all part of the Multi-Ethnic
Study of Atherosclerosis and Air Pollution and none
of them had heart disease at the start of the trial.
To determine the amount of air pollution to which
the participants were exposed, the researchers created
models to estimate the particulates in the air in and
around the volunteers homes, using information
from the Environmental Protection Agency s air quality
readings, as well as data that took into account density
of car traffic, roadways and other sources of pollution
near the people s homes.
The scientists also used ultrasound to measure
blood vessel characteristics both at the beginning of
the study and again three years later.
After accounting for behaviours like smoking, which
can independently affect heart disease risk, they
found that the thickness of the carotid arteries that
supply blood to the head and neck increased by 14
μm (micrometres) each year. Participants who were
exposed to higher levels of air pollution in their home
had blood vessels that thickened faster compared to
others living in their area with lower exposure lev-
els.Thickening of blood vessels is a sign of hardening
of the arteries, as inflammation lures in clotting factors
and other immune agents to patch up worn areas;
as these compounds build, the vessels stiffen and
thicken, losing their ability to flex and adjust to the
varying levels of pressure created by the blood flow.
High levels of a fine air pollutant called PM2.5 was
specifically linked with faster thickening of the inner
two layers of the carotid artery, a vessel that serves
as a sentinel for the state of other arteries throughout
the body. However, the study also showed that if
levels of PM2.5 were reduced in the participants
homes, the pace of thickening slowed.
"Linking these findings with other results from
the same population suggests that persons living in
a more polluted part of town may have a two-per-
cent higher risk of stroke as compared to people in
a less polluted part of the same metropolitan area,"
said study author Sara Adar, a John Searle assistant
professor of epidemiology at the University of Michigan
School of Public Health in a statement.
The researchers say that understanding the pathway
of PM2.5 and how it influences hardening of the
arteries will help future studies investigating how air
pollution affects heart disease. Previous studies have
linked car pollution to a higher risk of childhood can-
cers and even autism.
And a study published last year even found an
association between an expectant mother s exposure
to pollution during pregnancy and obesity in children.
The researchers found that higher levels of polycyclic
aromatic hydrocarbons (PAHs) which are present in
cigarette smoke and car exhaust, in the mother s
blood during the third trimester can disrupt hormones
that regulate growth and development.
While these studies all highlight associations, and
not causal relationships between pollution and health
risks, they point to potentially harmful exposures
that could trigger damaging physiological changes.
They are particularly concerning since many people
can t avoid exposure to pollutants, particularly from
cars, so public health experts recommend focusing
on heart disease risk factors that are in people s con-
trol---such as not smoking.
Is air pollution contributing
to hardened arteries?
YOUR DAILY HEALTH
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