Joe rode his bicycle to work and back every day. As a health care professional, he knew he was benefiting his health as well as the environment. For part of his route, though, the bicycle path passed right next to the freeway, and he knew he was also putting himself at more than his share of health risks.
Most Americans understand the damage that polluted air can cause to the lungs and respiratory system. They are less knowledgeable about the similarly high risk to the heart and cardiovascular system.
The World Health Organization estimates that two million people die each year because of heart problems made worse by high levels of ozone. And data from the large Women’s Health Initiative found that subjects living in areas of relatively high pollution were more likely than other women to die of heart attacks and other cardiovascular problems.
Older persons with established health problems are at greatest danger, of course, but young, fit athletes are not exempt and, in some ways, may be even more vulnerable. During vigorous exercise, we breathe in 10 to 20 times more air than when we’re sedentary. We breathe more deeply and mostly through the mouth–bypassing the protective filters of the nose.
According to a 2004 Australian review of pollution studies, even low concentrations of pollutants caused health damage to persons during exercise similar to those caused by higher concentrations in sedentary persons.
The Olympic games are typically held in major metropolitan areas where pollution is high–Beijing, Athens, Los Angeles and, now, London. The traffic and crowded conditions surrounding the games tend to make the air quality worse.
Changes Bring Relief
As a condition for hosting the 2008 games, China put tight restrictions on automobile use and industrial production in the vicinity of Beijing for the period just before and during the games. These resulted in dramatic, although temporary, decreases in all of the major components of air pollution. And a study of 125 healthy medical residents during this period found significant improvements in cardiovascular health, including lower heart rate, systolic and diastolic blood pressure and markers of inflammation. Animal studies have found that inflammation is a major cause of the adverse effects related to poor air quality.
The American Heart Association’s Scientific Statement on “Air Pollution and Cardiovascular Disease” [2004] singled out particulate matter as a major contributor to heart disease morbidity and mortality. These are the fine particles produced by automobile exhaust that form deposits in the lungs, causing inflammation. Some of these particles then enter the blood stream, creating an inflammatory response throughout the body that contributes to high blood pressure, atherosclerosis (hardening of the arteries) and impaired blood vessel function. According to one study, the risk of dying from a heart attack or stroke increased 76 percent for each 10-microgram increase in particulate matter pollution.
The 2010 update of the AHA Scientific Statement points out that even short-term exposure to particulate matter pollution–a few hours to a few weeks–can trigger heart-related deaths and events, including heart attack, stroke, heart failure and arrhythmias. Long-term exposure creates even greater risks and can reduce life expectancy by several months to a few years.
Ozone, another major component of air pollution, has a different kind of effect. In the upper atmosphere, ozone helps shield the planet from radiation; at ground level, it is commonly referred to as smog, and it includes pollutants from power plants and industry as well as motor vehicles. Ground ozone often reaches peak levels on hot, sunny days.
One study published in Circulation [June, 2012] found that healthy young adults (aged 19 to 33) showed significant changes in heart function when exposed to ozone polluted air for two hours at a time twice over a two-week period.
These changes included:
• increases in interleukin-1-beta, an indicator of inflammation and a major player in heart disease;
• decreases in natural clot-dissolving substances in the arterial walls; and
• changes in heart rhythm, indicating a malfunction in the way the nervous system controls heart rate.
These are basically the elements of a heart attack, although in the young, healthy subjects they were temporary and caused no problems. In older persons or those with medical conditions such as heart disease or diabetes, the stress to the cardiovascular system caused by ozone pollution could be deadly.
Most of us have little control over the quality of air in our environment. Generally, jobs are located in areas where factories spew out pollutants and freeways are filled with exhaust from commuters’ vehicles.
The Harvard Six Cities study, started in 1974 and collecting data on 8,000 subjects over a period of 14 to 16 years found that those living in more polluted cities had a higher risk of hospitalization and early death from lung and heart disorders. The risk of harm was much greater for fine particle pollution than ozone.
For people living in these areas, the solution is not to quit exercising nor to stay inside, where air is also likely to be polluted, at least to some degree. Inactivity will lead to other kinds of health problems that will make the heart even more vulnerable to the effects of polluted air.
As he is cycling to work, Joe is well aware of the dangers in the air he’s breathing. He has adjusted his route several times so that he spends less time near busy traffic throughways. He pays attention to the Air Quality Index (AQI) and AIRNow, and whenever possible, tries to avoid the heaviest exposure to polluted air.
Ultimately, though, when it comes to polluted air, you can run from it, but you can’t hide. Even the Sequoia National Forest warns hikers about unhealthy levels of ozone and particulate matter. A solution is possible only when Americans understand and accept the substantial health risks that go with a lifestyle that counts on the internal combustion engine to get them from one place to another.
REFERENCES:
“Air pollution & cardiovascular disease,” NIEHS, NIH, last reviewed July 6, 2011.
“Air pollution holds risks for athletes who exercise outdoors,” New York Times, July 12, 2007.
Robert D. Brook, M.D., et al, ”Particulate matter, air pollution and cardiovascular disease: AHA Scientific Statement, an update to the Scientific Statement from the American Heart Association,” Circulation, 2010;121:2331-2378.
Josephine Forster and Michael McCarthy, “Polluted air ‘puts Olympic athletes at risk’,” The Independent, January 16, 2012.
Gary Fuller, “Pollution watch: Olympic athletes vulnerable to bad air quality,” The Guardian, June 10, 2012.
Diane R. Gold, et al, “Ambient pollution and heart rate variability,” Circulation, March 21, 2000.
Maggie L. Grabow, et al, “Air quality and exercise-related health benefits from reduced car travel in the Midwestern United States,” Environmental Health Perspectives, 2012;120(1):68-76.
“Health effects of air pollution,” Harvard Health News, August, 2005.
Barbara Hoffman, et al, “Opposing effects of particle pollution, ozone, and ambient temperature on arterial blood pressure,” Environmental Health Perspectives, 2012;120(2):241-246.
Nino Kunzli, M.D., Ph.D., et al, “Hardening of the arteries linked to air pollution, NIEHS, NIH, last reviewed September 18, 2007.
G. Lippi et al, “Air pollution and sports performance in Beijing,” International Journal of Sports Medicine, August, 2008.
Kathleen Masterson, “Air pollution linked to heart attacks, heart association says,”NPR, May 11, 2010.
Kristin Miller, et al, “Air pollution & cardiovascular disease in women,” NIEHS, NIH, last reviewed September 17, 2007.
Alex Mroszcyzk-McDonald, “Athletes and air pollution,” BodyHealth.com.
“Ozone pollution bad news for heart patients,” Medical News Today, June 27, 2012.
Michael O’Riordan, “Air pollutants mediate effects on heart health through inflammation and thrombosis,” Heartwire, May 16, 2012.
Michael O’Riordan, “Growing evidence linking air pollution with cardiovascular disease: AHA,” Heartwire, May 11, 2010.
Juha Pekkanen, M.D., et al, “Particulate air pollution and risk of ST-segment depression during repeated submaximal exercise tests among subjects with coronary heart disease,” Circulation, August 20, 2002.
W.E. Pierson, et al, “Implications of air pollution effects on athletic performance,” Medicine and Science in Sports and Exercise, June, 1986.
08/08/2012
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