Medical News Today  [Printer-friendly version]
March 11, 2006


New data from a four-year study of 11.5 million Medicare enrollees
show that short-term exposure to fine particle air pollution from such
sources as motor vehicle exhaust and power plant emissions
significantly increases the risk for cardiovascular and respiratory
disease among people over 65 years of age. The study, funded by the
National Institute of Environmental Health Sciences, a component of
the National Institutes of Health, is the largest ever conducted on
the link between fine particle air pollution and hospital admissions
for heart- and lung-related illnesses.

The study results show that small increases in fine particle air
pollution resulted in increased hospital admissions for heart and
vascular disease, heart failure, chronic obstructive pulmonary
disease, and respiratory infection. "The data show that study
participants over 75 years of age experienced even greater increases
in admissions for heart problems and chronic obstructive pulmonary
disease than those between 65 and 74 years of age," said National
Institutes of Health Director Elias A. Zerhouni, M.D.

The National Institute of Environmental Health Sciences and the U.S.
Environmental Protection Agency provided funding to researchers at the
Johns Hopkins Bloomberg School of Public Health for the study. The
study results are published in the March 8, 2006 issue of the Journal
of the American Medical Association.

According to the study, these findings document an ongoing threat from
airborne particles to the health of the elderly, and provide a strong
rationale for setting a national air quality standard that is as
protective of their health as possible.

"These findings provide compelling evidence that fine particle
concentrations well below the national standard are harmful to the
cardiovascular and respiratory health of our elderly citizens," said
NIEHS Director David A. Schwartz, M.D. "Now that the link between
inhaled particles and adverse health effects has been established, we
must focus our efforts on understanding why these particles are
harmful, and how these effects can be prevented."

Fine particle air pollution consists of microscopic particles of dust
and soot less than 2.5 microns in diameter - about thirty times
smaller than the width of a human hair. These tiny particles primarily
come from motor vehicle exhaust, power plant emissions, and other
operations that involve the burning of fossil fuels. Fine particles
can travel deep into the respiratory tract, reducing lung function and
worsening conditions such as asthma and bronchitis.

The researchers based their fine particle analysis on 11.5 million
Medicare enrollees who lived in 204 U.S. counties with populations
larger than 200,000. Using billing records for 1999 to 2002, they
tracked daily counts of hospital admissions for eight major outcomes -
heart failure, heart rhythm disturbances, cerebrovascular events such
as stroke or brain hemorrhage, coronary heart disease, peripheral
vascular disease or narrowing of the blood vessels, chronic
obstructive pulmonary disease, respiratory infection, and injury.

The investigators obtained daily measurements of fine particle
concentrations from a network of air monitoring stations provided by
the Environmental Protection Agency's Aerometric Information Retrieval
Service. The average fine particle concentration for the 204 counties
over the three-year period was 13.4 micrograms per cubic meter of air,
slightly below the national air quality standard of 15 micrograms per
cubic meter for an annual average.

"When we analyzed the data for heart failure, we observed a 1.28
percent increase in admissions for each 10 microgram per cubic meter
increase in fine particle pollution," said Francesca Dominici, Ph.D.,
an associate professor of biostatistics with the Johns Hopkins
Bloomberg School of Public Health and lead author on the study. "Most
of these admissions increases occurred the same day as the rise in
fine particle concentration, which suggests a short lag time between
the change in pollution and the subjects' response."

The data also showed that the risk for air pollution-related
cardiovascular disease was highest in counties located in the Eastern
United States. "Identifying the various factors that might contribute
to these differences between eastern and western regions is a very
complex question that we must address," said Dominici.

According to Dominici, fine particles pose a significant health
problem because they penetrate deep into the lungs, and some may even
get into the bloodstream. "Now that we know that inhaled particles can
affect cardiovascular and respiratory health, we must identify the
specific characteristics of fine particles that produce these adverse
health effects," she said. "In the meantime, these findings underscore
the need for a national air quality standard that adequately protects
the respiratory health of our citizens."


NIEHS, a component of the National Institutes of Health, supports
research to understand the effects of the environment on human health.
For more information on fine particle air pollution and other
environmental health topics, please visit the NIEHS website at

Reference: F. Dominici, D. Peng, M. Bell, L. Pham, A. McDermott, S.L.
Zeger, J.M. Samet. Fine Particulate Air Pollution and Hospital
Admissions for Cardiovascular and Respiratory Diseases. Journal of
American Medical Association 295, March 2006.

Contact: John Peterson
NIH/National Institute of Environmental Health Sciences
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