After the games came to an end, however, many of the temporary pollution-reducing measures were relaxed, and pollution levels climbed once more.
Although the period of blue skies in Beijing may have been fleeting, researchers from the University of Southern California (USC) and colleagues have found that even such a small window of cleaner air may have proved useful for residents' cardiovascular health. That's according to a new study published yesterday in the Journal of the American Medical Association.
"Heart disease in on the rise everywhere in the world - especially in the developing world," says Dr. Junfeng Zhang, Professor of Environmental and Global Health at USC, and senior author on the study. "So, we thought that this drastic a change in air quality in a relatively short period of time could provide a unique experimental condition to really detect biological changes relevant to cardiovascular health."
For the study, Zhang and colleagues recruited 125 healthy, young people, all of whom worked at a local Beijing hospital. They measured several markers of heart health in study participants before, during, and after the Olympic period - most notably the von Willebrand factor and soluble P-selectin (sCD62P), indicators of blood clotting and noted precursors to cardiovascular events such as stroke and heart attack. Zhnag's team also measured daily concentration of air pollutants.
"We hypothesized that biomarkers of cardiovascular health would change as air pollution levels change," says Zhang. "And that is, in fact, what we found." As pollution levels dropped, so did indicators of cardiovascular risk in study participants. As pollution levels rose back to pre-Olympic levels, indicators rose right alongside.
While the link between cardiovascular disease and air pollution has long been acknowledged by the American Medical Association, this study is the first to directly look at the underlying mechanisms by which air pollution affects the heart.
"[Other] epidemiological studies have linked air pollution, especially fine particulate matter - 'soot' -- with adverse cardiovascular outcomes, but these studies seldom shed any light on biological mechanisms underlying this association," said Dr. John M. Balmes, Professor of Pulmonary Medicine, University of California San Francisco, responding to the study in an email to the Atlantic. "This study took advantage of the decreased air pollution of the Olympics period in Beijing to investigate potential mechanisms of the adverse cardiovascular effects."
But beyond understanding the mechanisms by which air pollution may impact cardiovasular health, Zhang says there's another important take-away point in his study: air pollution doesn't discriminate by age.
"'I'm young, I'm super healthy, I shouldn't worry about those things, is how young people think," Zhang says. "But this study shows that even if you're young and healthy, your physiology can actually detect the impact of air pollution."