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Wednesday 15th March, 2006
New data even short-term exposure to common air pollutants
dangerous for people over 65 years of age.
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.
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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
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."
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.