E-M:/ Particle air pollution increases ischemic strokes -- Detroit included in study

["Alex J. Sagady & Associates" <ajs@sagady.com>]

DETROIT WAS INCLUDED IN THIS STUDY....


American Heart Assn News Release
FOR RELEASE: 
4 p.m. EDT, Thursday
Oct. 27, 2005
 
American Heart Association rapid access journal report:
Air pollution linked to ischemic strokes 

DALLAS, Oct. 28 ? Already a factor in heart attacks, air pollution
also increases the risk for ischemic strokes ? those caused by a blood
clot ? according to a study in Stroke: Journal of the American Heart
Association. 

Hemorrhagic strokes, which occur when a blood vessel ruptures, were
not affected by the level of pollution.

Compared to days with relatively low air pollution levels, the risk of
ischemic stroke ? the most common type of stroke ? was 1 percent higher
on days with relatively higher air pollution, said Gregory Wellenius,
Sc.D., postdoctoral fellow in cardiology at Beth Israel Deaconess Medical
Center in Boston.

 ?It appears that air pollution has only a small effect on acute
ischemic events of either the heart or brain, but everybody in those
cities is exposed.  So, while the relative risk may be small, the
absolute risk in terms of excess number of strokes can be quite high,
especially when you realize that someone in the United States has a
stroke every 45 seconds,? Wellenius said.

According to American Stroke Association statistics, 700,000 Americans
suffer strokes every year. 

Previous studies have shown that exposure to air pollution increases the
risk of heart attack, hospitalization for heart failure, and the
triggering of implantable cardioverter-defibrillators (electronic devices
that shock the heart to end dangerous heartbeat disturbances). 
Studies also have suggested that air pollution might increase the risk
for stroke, but most have not distinguished between ischemic and
hemorrhagic strokes.

      Wellenius and his co-authors evaluated the
association between daily levels of particulate matter smaller than 10
micrometer in diameter (PM10) and hospital admission for
ischemic and hemorrhagic stroke among Medicare recipients in nine U.S.
cities: Birmingham, Ala., Chicago, Cleveland, New Haven, Conn.,
Detroit, Minneapolis, Pittsburgh, Salt Lake City and Seattle.

The researchers used standard measurements of PM10
concentration, which includes particles from car and truck exhaust, power
plants, refineries and other substances that make up air pollution. 
Particulate matter measurements provided by the U.S. Environmental
Protection Agency covered more than 37,000 days in the nine cities. 
Daily and hourly measurements were also obtained for the pollutants
carbon monoxide, nitrogen dioxide and sulfur dioxide.

Medicare data for the nine cities revealed 155,503 hospital admissions
for ischemic stroke.  Those patients were an average age of 79, 75
percent were white and 61 percent were female.  The data found
19,314 admissions for hemorrhagic stroke.  Hemorrhagic stroke
patients were on average 78 years old, 78 percent white and 59 percent
female.

After separating the patients into quartiles according to particulate
matter readings, Wellenius found that an increase in pollution
concentration from the lowest to the highest quartile was associated with
a 1.03 percent rise in risk for hospital admissions due to ischemic
stroke on that day.  Similar associations were seen for carbon
monoxide, nitrogen dioxide and sulfur dioxide.

In contrast, the rate of hemorrhagic stroke did not rise with increases
in quartiles of air pollution levels.  The null findings for
hemorrhagic stroke may be due to the small number of hospital admissions
for hemorrhagic stroke and lack of statistical power.

This study supports earlier findings that link air pollution to diseases
of the heart and lungs, and suggests that ambient particles may also
trigger other cardiovascular events such as stroke.

?Taken together with previous work, these results support the idea that
reducing exposure to particulate matter may reduce the risk of strokes
and heart attacks.? 

The researchers theorize that air pollution may increase ischemic stroke
risk by promoting atherosclerotic plaque disruption and blood clot
formation.  However, they said more studies are needed to better
understand the mechanisms related to the increased stroke risk.

 ?We need to replicate this study in other populations and do more
studies to see which components of air pollution are most toxic and
whether there are individuals within the population that are more
susceptible than others to the effects of air pollution,? Wellenius
said.
Co-authors are Joel Schwartz, Ph.D. and Murray Mittleman, M.D.,
Dr.PH.

The study was funded by the National Institutes of Health and the U.S.
Environmental Protection Agency.

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