David Siscovick, MD, MPH, the Academy’s Senior Vice President for Research and co-author of one of the largest studies on air pollution and health, explains how foul air may be increasing rates of heart disease.
The air you breathe may harm your heart, according to a new, large-scale study conducted in six, major American cities. The Multi-Ethnic Study of Atherosclerosis and Air Pollution (MESA-AIR), a 10-year look at cities that are home to more than 15 million people, asked the question: Are the levels of air pollution commonly observed in urban areas linked to the progression of coronary atherosclerosis—a primary cause of cardiovascular disease?
The answer is yes. The MESA-AIR Study is the first to provide evidence of a possible biological mechanism for air pollution’s negative impact on heart disease. In the cities studied—New York, Los Angeles, Chicago, Baltimore, St. Paul Minnesota, and Winston Salem, North Carolina—living in an environment with polluted air was associated with increased atherosclerosis (hardening of the arteries) in healthy individuals, a major determinant of heart attacks.
The study was not the first to discover a connection between air pollution and cardiovascular health. Previous research found that exposure to polluted air not only contributed to heart disease, but it also increased cardiovascular disease mortality rates.
The result of a $33 million federal grant, the largest research award ever made by the United States Environmental Protection Agency (EPA), the MESA-AIR study is of great relevance to policy makers, urban planners and experts in population health, as it strengthens the evidence base for the importance of acceptable air quality. The results fill an important gap in knowledge and are expected to inform US Air Quality Standards.
New York City Air
MESA-AIR also revealed that New York City’s nitrogen oxide (NOx) levels (most often generated by burning fossil fuels) were higher than those found in the Los Angeles basin, but NYC’s levels of particulate matter (PM 2.5, commonly produced by combustion activities or industrial activity) were similar to those found in Chicago and Baltimore.
Surprisingly, even low levels of pollution had an impact on the cardiovascular health of the residents of the communities studied. There was little evidence of a threshold below which levels of air pollution were safe.
Link to Heart Health
To tease out the connection between different types of pollution and health, we separated the particles and gases that comprise polluted air, the type often generated by various sources, such as traffic (assessed by distance from roadways), diesel exhaust and emissions from power plants. While levels of air pollution have been declining over time in the US, we found a direct, dose-response relationship between the levels of small PM 2.5 and NOx commonly seen in US communities and the progression of coronary atherosclerosis.
Because our work here at the Academy recognizes that sharing knowledge with our neighbors here in East Harlem and the residents of the nation’s cities is just as important as talking to policy makers, we are making an effort to spread the word.
The results of MESA-AIR should serve as a call to action to policy makers across the country. While levels of air pollution have decreased in recent years, this new research shows that our air quality is still a threat to optimal health.
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