American Heart Association Scientific Statement:
DALLAS, May 10, 2010 — 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.
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.
View the full air pollution statement here
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, also published in Circulation: Journal of the American Heart Association.
The major source of PM2.5 is fossil fuel combustion from industry,
traffic, and power generation. Biomass burning, heating, cooking,
indoor activities and forest fires may also be relevant sources,
particularly in certain regions.
“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 said 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:
- “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.
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 ways 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
nerves in the lungs. These responses can start a cascade of changes
that adversely affect the rest of the body, 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
increase 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,” he said.
Recommendations include:
- Physicians should 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.
- 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 and the Environmental Protection Agency
are co-sponsoring a Congressional briefing on Capitol Hill to educate
lawmakers about the link between air pollution and cardiovascular
disease. The association plans to monitor opportunities at the state
and federal level to decrease the amount of particulate matter air
pollution.
Editor’s Notes: (American Heart Association)
Downloadable stock footage and animation, including video of the environment and outdoor physical activity, are available at
www.americanheart.mediaroom.com, click on “Multimedia Resources.”
