In-Car Air Pollution May Raise Health Risks
Dirty Air Inside Cars May Be Especially Hazardous to People With Health Problems
April 12, 2004 -- Spending a lot of time in your car may put
your heart's health at risk. A new study shows that prolonged exposure to dirty
air inside vehicles could trigger potentially dangerous changes in heart
Prior studies have shown that exposure to fine airborne
particulate matter is associated with cardiovascular events and mortality in
older and cardiac patients. But now researchers say air pollution levels inside
cars which are generally lower than outside, may also increase the risk of
heart attack or stroke in people with existing health problems by changing the
way the heart functions.
The study showed that exposure to in-car air pollution caused
changes, such as increased markers of inflammation and increased blood clotting
proteins, variations in heart rate, and other changes in the functioning of the
cardiovascular system, in nine healthy state highway patrol troopers who worked
in their cars.
In-Car Air Pollution Hazards
In the study, which appears in the April issue of the
American Journal of Respiratory and Critical Care Medicine, researchers
equipped each of the North Carolina State Highway Patrol cars with air quality
monitors. Each of the troopers also wore a monitor that measured heart rates
during four consecutive 3 p.m. to midnight shifts and until the next morning,
and had their blood drawn 14 hours after each shift.
"Pollutant levels in the patrol cars of the analyzed
troopers were highly variable but were always well below occupational threshold
values," says researcher Michael Riediker, in a news release.
"In-vehicle [particulate matter] was 24% lower than ambient and roadside
concentrations, whereas in-vehicle carbon monoxide, nitrogen dioxide,
aldehydes, hydrocarbons, and some metals were elevated."
Researchers say that, on average, troopers spent 35% of their
shift away from their cars, mostly inside buildings, such as offices, jail,
hospitals, or at dinner.
Overall, researchers say that the troopers were in excellent
health and appeared to be at low risk for heart or other health problems. But
they found prolonged exposure to air pollution inside the troopers' vehicles
prompted changes in the heart rate that could be hazardous in less healthy
Heart rate variability measures the nervous system function of
the heart, which controls blood vessel widening or stiffening, blood pressure,
the heart's electrical activity and its ability to contract and pump blood.
Previous studies have shown that heart rate variability is decreased in heart
conditions such as coronary heart disease and heart rhythm abnormalities like
"This study shows a strong and consistent increase of heart
rate variability in association with [particulate matter]," says Riediker.
He says that the pattern of change seen in the officers suggested changes in
the cardiovascular system.
Researchers say those changes do not seem desirable and show
that exposure to in-car air pollutants "should be minimized."