|Elderly Have Higher Risk for Cardiovascular, Respiratory Disease
From Fine Particle Pollution
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
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 http://www.niehs.nih.gov/home.htm.
The National Institutes of Health (NIH) — The Nation's Medical Research
Agency — includes 27 Institutes and Centers and is a component of
the U.S. Department of Health and Human Services. It is the primary federal
agency for conducting and supporting basic, clinical and translational medical
research, and it investigates the causes, treatments, and cures for both common
and rare diseases. For more information about NIH and its programs, visit http://www.nih.gov.