A new study reports that air pollution takes a greater
toll on the hearts of black Americans than whites, in part because they often
live in poorer areas with more pollution.
"The greater risk of death from heart disease
among blacks, compared with whites, is partially explained by higher exposure
to air pollution," said lead researcher Dr. Sebhat Erqou, a fellow in
cardiovascular disease at the University of Pittsburgh.
The western Pennsylvania study looked at the
relationship between heart disease and a component of air pollution known as
fine particulate matter. Fine particulate matter (called PM2.5, which is about
40 times smaller than the width of a human hair) stems from factories,
vehicles, power plants, fires and secondhand smoke.
Researchers found that blacks living in areas where
this type of pollution is high have a 45 percent higher risk of heart disease
and death from any cause than whites, even after taking into account other
common risk factors.
But about one-quarter of that elevated risk was
attributed to their greater exposure to dirty air, which correlated with
poverty, Erqou said.
Blacks and other minorities more often live close to
sources of environmental pollution, such as highways, the researchers said in
background notes. As income and education increased, the impact of air
pollution decreased, Erqou said.
Chronic exposure to air pollution has been associated
with numerous ill effects, included elevated blood sugar, poorly functioning
blood vessels, heart disease and death, he noted.
This study reflects, again, racial disparities that
exist in medical outcomes, said Dr. Rachel Bond, associate director for women's
heart health at Lenox Hill Hospital in New York City.
"Air pollution clearly has a detrimental effect on
the black community disproportionate to the white community with respect to
cardiac disease outcomes," said Bond, who was not part of the study.
Another New York specialist who was not involved with
the research pointed to the broad role economic differences can play.
"Exposure to air pollution may be more of a factor
of socioeconomic status than race itself, and there may be confounders such as
smoking history, home environment and occupation, which can affect
health," said Dr. Walter Chua. He's a senior pulmonary attending physician
at Long Island Jewish Forest Hills.
For the study, Erqou and colleagues reviewed data on
PM2.5 and black carbon, which is an ultrafine component of PM2.5, from a
Pittsburgh-area air monitoring campaign.
The researchers combined that with information from an
ongoing heart study involving more than 1,700 residents (average age 59) of
western Pennsylvania.
Each year, participants complete questionnaires that
ask about heart-related hospitalizations, heart attacks, acute coronary
syndrome, stroke, angioplasty or death from heart disease.
Erqou's team found that greater PM2.5 exposure was
associated with increased blood sugar, worse blood vessel function, and higher
odds for problems such as heart attack and stroke, and death from all causes.
The investigators also found that compared with whites,
blacks had significantly higher average exposures to PM2.5 and black carbon.
A weakness of the study is that it's limited to one
city, so the findings might be different in other locales, Erqou said. Also,
the study only found an association rather than a cause-and-effect link.
Chua said it would be interesting to look at other
major cities, including New York and San Francisco, to see if these disparities
still exist, given that those cities are more diverse, he said.
Meanwhile, "the push to maintain good air quality
should still continue," Chua said.
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