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Linking Air Pollution and Heart Disease

According to The American Heart Association, someone dies from cardiovascular disease every 40 seconds in the United States. Almost half of Americans have at least one of three main risk factors for heart disease: high blood pressure, high cholesterol, and a smoking habit. Doctors tell their patients to exercise more, watch what they eat, and to quit smoking to lower their cardiovascular risk—but there are other factors that we should also recognize as having an impact on our heart health, like air pollution exposure.graphic of a plaque buildup in an arteryFat accumulation in the wall of a coronary artery.

EPA conducts research and funds studies to advance our understanding of the link between air pollution and heart health. These research efforts support the National Ambient Air Quality Standards (NAAQS) and help provide better air quality for everyone. Most recently, researchers funded by EPA’s STAR grant program at the University of Washington completed the Multi-Ethnic Study of Atherosclerosis Air Pollution Study (MESA Air), a decade-long study that reveals a direct link between air pollution and atherosclerosis, which is a buildup of plaque in the coronary artery that can affect heart health.

Nearly 100 peer reviewed articles summarizing the findings of MESA Air have been published since the research began in 2004, but in May 2016, the medical journal The Lancet published a seminal article by lead investigator Dr. Joel Kaufman.  This study found that long-term exposure to particulate matter and nitrogen oxides at levels close to the National Ambient Air Quality Standards (NAAQS) can prematurely age blood vessels and contribute to a more rapid buildup of calcium in the coronary artery.

This buildup of calcium can restrict blood flow to the heart and other major blood vessels —increasing the likelihood of cardiovascular events like heart attack and stroke.

While previous studies have linked air pollution and heart disease, this study provides “a finer degree of evidence that air pollution accelerates the process of atherosclerosis” says Kaufman, thanks to its extensive length, diversity in subject participants, definitive scope, and rigorous data collection.

To reach this conclusion, researchers collected and analyzed substantial amounts of data on 6,800 diverse participants and the air quality in six regions where they lived. Regional air quality data was collected from the national monitoring network—a group of regulatory monitors that EPA uses to assess air quality—to gain an understanding of how individuals are exposed to air pollution from day to day. Some of this regional air quality data can be publicly accessed on AirNow.gov.

In addition, local air quality monitoring was conducted in the communities and directly outside the homes of study participants. Some homes were equipped with indoor air monitors in order to assess particulate matter pollution inside, and researchers even equipped certain participants with personal air monitors to wear.

To collect medical data, researchers used noninvasive exams that tracked heart health in participants over the study period. Participants received ultrasound exams to determine the thickness of the arterial wall in the arteries, CAT scans to track coronary artery calcium accumulation, and blood pressure tests. Participants also received personal health recommendations based upon their test results as part of the study. 

Using the air quality and medical data collected, researchers determined that there was a direct link between air pollution exposure and plaque buildup: healthy individuals exposed to air particle pollution over the long term had accelerated cases of atherosclerosis—to the extent that some participants’ risk for heart attack increased. In fact, the investigators found that the higher the exposure level, the faster atherosclerosis progresses.

MESA Air provides evidence that long-term exposure to air pollution is a cardiovascular disease risk factor that should be taken seriously. In addition to encouraging policy makers to consider the long-term impacts of low levels of air particle pollution and motivating healthcare providers to learn more about the effects of air pollution on the cardiovascular system, the study emphasizes the importance of monitoring air quality to protect heart health.

As EPA and other researchers continue to study the effects of air pollution on heart health, you can take action and pay attention to air pollution in your area by using EPA’s Air Quality Index, which is available on the AirNow.gov web page. You can also access more information from EPA’s Healthy Heart Toolkit to learn more about the science EPA is doing to protect heart health.

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