Exposure to traffic fumes increases the
risk of heart attack, or strokes and potentially fatal blood clots in the leg.
Pollution from cars and trucks and industrial plants has been shown to harm
people with coronary artery disease, causing worrying changes on the heart
traces of patients recovering from heart attacks. Previous studies have shown
it alters the blood’s coagulation properties and heightens the risk of deep
vein trombosis.
Particulate pollution is already known to increase
the risk of heart attacks and other serious diseases. The risk of heart attack
increases exponentially after exposure to even slightly higher amounts of metal
and dust.
Harvard researchers monitored 48 patients
from the Boston
area with coronary artery disease using portable electrocardiograph machines.
The elctrocardiograms of the patients studied showed unusual changes in the
electrical conductivity of the heart called ST-segment depression. Increases in
ST-segment depression were higher in patients recovering from a heart attack
compared with other patients, the researchers said.
Guidelines from the American Heart
Association and the American
College of Cardiology
advise patients who have just been discharged from hospital after a heart
attack to avoid heavy traffic because of the stress of driving. Traffic
exposure “involves pollution exposure as well as stress,” researchers said.
Even people without a heart attack should avoid or reduce heavy traffic exposure
after discharge.
“If the air pollution-associated ST-segment
changes represent either myocardial inflammation or risk of ischemia, then it
is possible that reduction in regional traffic and non-traffic associated air
pollution may reduce heart attack or risk for either ischemia, arrhythmia or
heart failure in patients with coronary artery disease in the period after
hospitalization,” said lead researcher Dr. Diane R. Gold, and associate
professor of medicine and environmental health.
The report was published in Circulation:
Journal of the American Heart Association. According to the World Health
Organization, air pollution accounts for three million deaths worldwide every
year. Cars, trucks and industrial plants are the greatest source of air pollution
emissions that increases the rates of heart attacks.
Other studies found that when particulates
are cut even for a short period of time, death rates fall. As an example, when
Hong Kong imposed reductions in sulphur dioxide, or when Dublin imposed a coal ban, they saw immediate
reductions in death rates from cardiovascular diseases.
Another study conducted by the Harvard
School of Public Health which focused on air pollution’s effects on clotting in
the veins found that exposure to air pollution from traffic fumes raises risks
of potentially fatal clots in the leg; it alters the blood’s coagulation
properties and heightens the risk of deep vein thrombosis (DVT). A study
published in 2007 in Stroke: Journal of the American Heart Association found
that breathing fine particle pollution during warm weather months can increase
stroke risk.
However, a person’s relative risk due to
air pollution is small compared with the impact of established cardiovascular
risk factors such as smoking, obesity, or high blood pressure, according to the
American Heart Association.
More research is needed to find out whether
the pollution-related ST-segment depression is related to increased heart
muscle inflammation, reduced oxygen flow, oxidative stress, or increased risk
of arrhythmias, researchers said.