Protect Against Heart Attack, Avoid Air Pollution

Air pollution associated with heart attack

Do something good for your heart and avoid air pollution. That may be easier said than done, but according to the findings of a new review and meta-analysis, it’s wise advice since exposure to major air pollutants for up to one week is significantly associated with an increased risk of heart attack.

Heart health and air pollutants are not a good mix

Results of the new report, which appears in the February 15 issue of the Journal of the American Medical Association, included data from 34 studies. The investigative team, headed by Hazrije Mustafic, MD, MPH, of the University Paris Descartes, evaluated the association between short-term exposure to ozone, carbon monoxide, nitrogen dioxide, sulfur dioxide, and particulate matter and the risk of heart attack (myocardial infarction, or MI).

The number of patients per study ranged between 399 and 302,153, and the number of air pollutants ranged from 1 to 6 (particulate matter was broken down into two different groups, based on size of the particulates). The study populations were mostly the general population, although five studies focused on elderly individuals.

About the air pollutants
All of the air pollutants evaluated, except ozone, were found to have a statistically significant association with heart attack risk.

Environmental sources of the remaining air pollutants are as follows:

  • Sulfur dioxide pollution comes mainly from electric utilities, especially those that burn coal. Other sources include petroleum refineries, paper pulp manufacturing, cement manufacturing, and machinery (e.g., trains, ships, diesel equipment).
  • Carbon monoxide comes primarily from the burning of fossil fuels, especially coal burning plants, and from cars and trucks,
  • Nitrogen dioxide is released by internal combustion engines (cars, boats, planes), butane gas heaters, and tobacco smoke
  • Particulate matter is extremely small particles and liquid droplets that can be composed of acids, soil and dust particles, organic chemicals, metals, and other substances. Sources can include roadways, construction projects, vehicles, industry, power plants, and forest fires


Why air pollutants may raise heart attack risk
Possible reasons why air pollutants are associated with heart attack were offered by the authors and included inflammation. They noted that “studies have shown that levels of inflammatory markers such as C-reactive protein are higher as a results of exposure to air pollution.”

They also pointed out that previous research has shown high levels of air pollution to be associated with an elevated heart rate. Yet another link may involve an increase in blood viscosity. “This association can promote thrombus [blood clot] formation, accelerate the progression of atherosclerosis, and weaken the stability of atherosclerotic plaques,” which could then trigger a heart attack.

Heart disease is the number of one killer in the United States and the cause of death in about 25% of cases. Every year, nearly 800,000 Americans experience their first heart attack, and an additional 470,000 have a recurrent attack.

In addition to exposure to air pollutants, other risk factors for heart disease include lack of exercise, obesity, high cholesterol, high blood pressure, smoking, and diabetes.

The authors said their meta-analysis was the first, to their knowledge, to evaluate the magnitude and quality of an association between major air pollutants and the risk of heart attack. While the authors recommended further research into the relationship between heart attack and air pollutants, it seems wise for individuals to take their heart health into their own hands and to avoid air pollution whenever possible, as well as the other risk factors associated with heart disease.

Environmental Protection Agency
Mustafic H, Jabre P, Caussin C, Murad MH, Escolano S, Tafflet M, Pe’rier M-C, Marijon E, Vernerey D, Empana J-P, Jouven X. Main air pollutants and myocardial infarction: A systematic review and meta-analysis. JAMA 2012; 307(7): 713-21

Image: Courtesy of Wikimedia Commons