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Healthy Heart Toolkit: Resources for Health Professionals

What is the link between Air Pollution and Cardiovascular Effects?

Extensive scientific evidence shows that breathing in fine particulate matter (PM2.5) over the course of many years can lead to an increased risk of developing cardiovascular disease and dying from the disease.  Short-term exposures to PM2.5 can trigger heart attack, ischemic stroke, abnormal heart rhythms and worsen heart failure in individuals with cardiovascular disease or older adults with medical conditions that put them at risk. The current National Ambient Air Quality Standards for PM2.5 that protect public health from the detrimental effects of the air pollutant are based on this evidence.

While the United States has experienced improved air quality and reductions in PM2.5, there are still many people who are exposed to high levels of the pollutant because of where they live and/or their vulnerability due to their health conditions. Individuals who live or work near roadways, railyards, ports or industrial areas may be exposed to high levels of PM2.5. Forest fires can also generate high levels of PM2.5, which can be transported great distances.

What is particulate matter (PM) and fine particulate matter (PM2.5)?

Particulate matter (PM) is a complex mixture of extremely small particles and liquid droplets that can be found in smoke and haze. Small airborne particles, also known as fine particulate matter (PM2.5), can be emitted from a number of different natural and man-made sources including forest fires or formed when gases emitted from power plants, industries and automobiles react in the air. Fine particles are a public health concern because after they are breathed in they generally pass through the throat and nose and enter the lungs from which point they can cause serious health effects on the rest of the body among people who are vulnerable.

How does PM2.5 cause death?

Among those who are vulnerable to the adverse effects of air particle pollution—either by frailty in old age or clinically significant heart and blood vessel disease—there are a number of possible ways that breathing in fine particles could lead to death by further harming the heart and blood vessels. These include changes in the way the heart and blood vessels function and blood clots, which can lead to heart attacks, stroke, life-threatening heart rhythm disturbances, and/or heart failure.

How does PM2.5 increase the risk for heart attacks?

Breathing in fine particles can alter blood vessels, which could include clogging arteries (atherosclerosis) after long-term exposures or forming blood clots after short-term exposures. These changes can result in a decrease in the supply of oxygen and nutrients to the heart and subsequently a heart attack.

How does PM2.5 cause a stroke?

There are a number of ways that breathing in fine particles can cause a stroke. Once inhaled the particles can trigger inflammation, changes in blood vessel function and the formation of blood clots, which can interrupt the flow of blood to the brain resulting in stroke.

How does PM2.5 cause cardiac arrest?

Among people with advanced heart disease who have internal cardiac defibrillators it has been shown that breathing in fine particles can disrupt the electrical function of the heart leading to potentially fatal abnormal heart rhythms (arrhythmias).

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