The American Heart Association has updated its scientific statement on the link between air pollution and cardiovascular disease. The evidence shows that exposure to fine particulate matter (PM2.5) can trigger heart attacks, strokes and death, especially in susceptible individuals such as the elderly and those with heart disease. Long-term exposure to elevated PM2.5 levels increases cardiovascular risk and reduces life expectancy. While reducing traditional risk factors is important, people should also limit their exposure to air pollution when possible and support policies to decrease particulate matter levels.

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American Heart Association scientific statement:
Evidence growing of air pollution’s link to heart disease, death
DALLAS, May, 10 — The scientific evidence linking air pollution to heart attacks,
strokes and cardiovascular death has “substantially strengthened,” and people,
particularly those at high cardiovascular risk, should limit their exposure, according
to an updated American Heart Association scientific statement.
The evidence is strongest for fine particulate matter (PM2.5) having a causal
relationship to cardiovascular disease, said the expert panel of authors who updated
the association’s 2004 initial statement on air pollution.
“Particulate matter appears to directly increase risk by triggering events in
susceptible individuals within hours to days of an increased level of exposure, even
among those who otherwise may have been healthy for years,” said Robert D. Brook,
M.D., lead author of the statement, which was written after review of
epidemiological, molecular and toxicological studies published during the past six
years.
“Growing evidence also shows that longer-term PM2.5 exposures, such as over a
few years, can lead to an even larger increase in these health risks. In this context, the
American Heart Association stated that PM2.5 should be recognized as a ‘modifiable
factor’ that contributes to cardiovascular morbidity and mortality.”
In the statement, the panel also concluded that there’s a:
-more-
Statement highlights:
• Air pollution is a risk factor for heart disease; however people can take
action to reduce their individual risk.
• Exposure to fine particulate matter over a few hours or weeks can trigger
cardiovascular deaths, heart attacks, strokes, heart failure and irregular
heartbeats, especially in susceptible individuals.
• Long-term exposure to elevated concentrations of fine particulate matter
even further increases cardiovascular risk and reduces life expectancy
probably by several months to a few years for those with higher
exposures.

2. Circ/Brook – 2
• “small yet consistent” association between short-term exposure to air pollution
and pre-mature death;
• strong level of evidence supporting a relationship between air pollution and
ischemic heart disease;
• “moderate, yet growing link” between air pollution and heart failure and
ischemic stroke;
• “modest” level of evidence supporting an association between air pollution and
peripheral vascular diseases, irregular heartbeats and cardiac arrest.
Understanding the relationships between PM2.5 exposure and cardiovascular
diseases and the underlying mechanisms responsible for the link have improved
significantly, Brook said.
The elderly and those with existing heart diseases, such as heart failure or
coronary artery disease, and perhaps those with diabetes appear to be at higher risk
from short-term PM2.5 exposure.
“The foremost message for these high-risk groups remains that they should work
to control their modifiable traditional risk factors – blood pressure, cholesterol,
diabetes, smoking,” said Brook, a cardiovascular medicine specialist and Associate
Professor in the Department of Internal Medicine at the University of Michigan in
Ann Arbor.
There are several mechanisms by which PM2.5 could affect the cardiovascular
system; however, one leading explanation suggests that several components of PM2.5,
once inhaled, can cause inflammation and irritate local nerves within the lungs. These
responses can initiate a cascade of changes beyond the lungs that adversely affect the
rest of the body by a variety of pathways, Brook said.
“It’s possible that certain very small particles, or chemicals that travel with them,
may reach the circulation and cause direct harm,” Brook said. “The lung nerve-fiber
irritation can also disrupt the balance of the nervous system throughout the body.
These responses can cause an increase in blood clotting and thrombosis, impair
vascular function and blood flow, elevate blood pressure, and disrupt proper cardiac
electrical activity which may ultimately provoke heart attacks, strokes, or even death.
“These studies also indicate that there is no ‘safe’ level of PM2.5 exposure. Any
future relaxation of current National Ambient Air Quality Standards is not
scientifically justifiable from a cardiovascular health standpoint,” he said.
Recommendations include:
• Emphasize treatment of traditional cardiovascular risk factors, which may
lessen patients’ susceptibility to air pollution.
• All patients with cardiovascular disease should be educated about the risks of
air pollution.

3. Circ/Brook – 3
• Healthcare professionals should consider educating patients without
cardiovascular disease but who are at high risk, such as the elderly, individuals
with metabolic syndrome or multiple risk factors and those with diabetes.
• Based on air pollution levels, as forecasted by the Air Quality Index available
in many media sources, recommendations for methods to reduce exposure and
limit activity should be followed depending on the patient’s level of risk.
Reducing exposure to air pollution takes effort at the population level by
implementing national policies as well as at the individual level, Brook said. “People
can limit their exposure as much as possible by decreasing their time outside when
particle levels are high and reducing time spent in traffic – a common source of
exposure in today’s world.”
The American Heart Association is partnering with the Environmental Protection
Agency, and plans to monitor opportunities to influence state and federal legislation
to decrease the amount of particulate matter air pollution.
Co-authors are: Sanjay Rajagopalan, M.D.; Arden Pope III, Ph.D.; Jeffrey R.
Brook, Ph.D.; Aruni Bhatnagar, Ph.D.; Ana Diez-Roux, M.D., Ph.D.; Fernando
Holguin, M.D.; Yuling Hong, M.D., Ph.D.; Russel Luepker, M.D.; Annette Peters,
Ph.D.; David Siscovick, M.D.; Sidney C. Smith, M.D.; Laurie Whitsel, Ph.D.; and
Joel D. Kaufman, M.D. Author disclosures are on the manuscript.
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Editor’s Notes:
• The American Heart Association’s Web site has more information on air pollution
and how it relates to cardiovascular disease.
• For national and local air quality index information, including current levels of
PM2.5 in your area, visit www.airnow.gov.
• For more information on air pollution, visit the U.S. Environmental Protection
Agency’s National Ambient Air Quality Standards NAAQS Web site:
http://www.epa.gov/airscience/.
NR10 – xxxx (Circ/Brook)