Air Pollution and Your Brain

By Michelle Becker

Graphic depiction of the brainNext week is Air Quality Awareness week, which is a time to reflect on how far we have come in our understanding of the health effects of air pollution. We know air quality can affect the lungs and heart and cause serious health problems, as documented in a large body of scientific literature. However, we don’t know very much about the potential effects on the brain.

That is why EPA supports research through its Science to Achieve Results (STAR) grant program to further examine potential health effects of air pollution. The Clean Air Research Center (CLARC) at Harvard University receives funds from EPA to explore the health effects of air pollution mixtures across organ systems and during various stages of human life.

Recently, the center published a study in the journal Stroke that looked at what may happen to the brain of older adults after long-term exposure to fine particle pollution (PM2.5), which is emitted from tail pipe emissions as well as other sources. The study included 943 individuals over the age of 60 with no history of dementia or stroke. They also lived within 1,000 meters (0.62 miles) of a major roadway where levels of air pollutants are generally higher.

Researchers looked at pictures of the brain using a technique called Magnetic Resonance Imaging (MRI) to identify the differences in certain brain structures. Then they considered the pictures in connection with the distance participants lived from a major road.

After considering all the data and a number of other factors that might affect the brain, the researchers found that exposure to outdoor PM2.5 was associated with a decrease in total cerebral brain volume and an increase in covert brain infarcts (known as “silent” strokes because there are no outward symptoms). The impact of being close to roadways was less clear.

So what are the potential implications? A decrease in cerebral brain volume is an indicator of degeneration of the brain, which can lead to dementia and other cognitive impairments. Also, an increase in covert brain infarcts increases a person’s risk for a major stroke.

To give you a better idea about PM2.5 (particulate matter of 2.5 microns in diameter) the average human hair has a diameter of 100 microns. So these air pollutant mixtures are roughly one quarter the diameter of a single hair on your head. That is to say, very small. Yet these small particles pack a big punch when it comes to our health. The study demonstrates an increase of just 2 micrograms per cubic meter can cause brain deterioration.

This study is one of the first to look at the relationship between air pollution and the brain so the evidence is suggestive. The study contributes to a growing body of scientific research that is exploring the cognitive connections to air pollution. So this week while we think about air quality, let’s remember that small things can make a big impact and that science can help us to learn more about air quality and our health.

About the Author: Michelle Becker, M.S, is currently working with the Air, Climate, and Energy research program in EPA’s Office of Research and Development through a Skills Marketplace opportunity. The project has allowed her to increase her scientific communication skills and to learn more about EPA funded research to protect human health.

Editor's Note: The views expressed here are intended to explain EPA policy. They do not change anyone's rights or obligations. You may share this post. However, please do not change the title or the content, or remove EPA’s identity as the author. If you do make substantive changes, please do not attribute the edited title or content to EPA or the author.

EPA's official web site is www.epa.gov. Some links on this page may redirect users from the EPA website to specific content on a non-EPA, third-party site. In doing so, EPA is directing you only to the specific content referenced at the time of publication, not to any other content that may appear on the same webpage or elsewhere on the third-party site, or be added at a later date.

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Air Pollution May be “Hard” on the Body’s Blood Vessels

Every day EPA researchers are advancing our understanding of how air pollution threatens heart health. We will be sharing some of the important studies under way and research discoveries during February in recognition of American Heart Month.

Healthy Heart graphic identifier

By Ann Brown

Can air pollution affect your heart? The short answer is—yes.  It can trigger heart attacks, stroke and cause other cardiovascular health problems. The long answer is that while we know that air pollution impacts the heart, additional research is needed to learn more about how this happens and what pollutants or mixtures are responsible.

An unprecedented 10-year study funded by EPA and the National Institutes of Health, called the Multi-Ethnic Study of Atherosclerosis and Air Pollution (MESA Air), is providing new information about the impacts of fine particle pollution on the arteries — the blood vessels that supply blood to the heart and other parts of the body. Fine particles are microscopic bits of matter that are emitted mostly from the burning of fossil fuel. They have been found to be bad for the heart, at high levels.

MESA Air is expanding our knowledge of a condition that can set you up for a heart attack—atherosclerosis. You may have heard of the term “hardening of the arteries.” Well, that refers to atherosclerosis when there is a buildup of fats, cholesterol, and calcium in and on the artery walls, most commonly known as plaque. The buildup of plaques can result in a blood clot, which can block the flow of blood and trigger a heart attack. While atherosclerosis is often considered a heart problem, it can affect arteries anywhere in your body; in the brain, it may lead to strokes.

The MESA Air study is finding evidence of associations between long-term fine particle pollution and the progression of atherosclerosis. Another important observation from the MESA Air study shows that long-term exposure to fine particle pollution limited the ability of arteries to widen when the body needs more blood flow to the heart, say, when running up a flight of stairs.

These are among the many discoveries coming out of the MESA Air study that are providing new insights into how air pollution can contribute to atherosclerosis and lead to heart attacks and strokes.

Those with heart disease who may be exposed to high levels of air pollutants can take action to protect their heart. A good first step is to be aware of high air pollution days. Check the daily air pollution forecast in your area by using the Air Quality Index at www.airnow.gov.

Learn more at epa.gov/healthyheart.

About the author: Ann Brown is the communications lead for EPA’s Air, Climate, and Energy Research Program.

 

Editor's Note: The views expressed here are intended to explain EPA policy. They do not change anyone's rights or obligations. You may share this post. However, please do not change the title or the content, or remove EPA’s identity as the author. If you do make substantive changes, please do not attribute the edited title or content to EPA or the author.

EPA's official web site is www.epa.gov. Some links on this page may redirect users from the EPA website to specific content on a non-EPA, third-party site. In doing so, EPA is directing you only to the specific content referenced at the time of publication, not to any other content that may appear on the same webpage or elsewhere on the third-party site, or be added at a later date.

EPA is providing this link for informational purposes only. EPA cannot attest to the accuracy of non-EPA information provided by any third-party sites or any other linked site. EPA does not endorse any non-government websites, companies, internet applications or any policies or information expressed therein.