Study Finds Link Between Air Quality And Cardiovascular Problems At Beijing Olympics
May 16, 2012

Study Finds Link Between Air Quality And Cardiovascular Problems At Beijing Olympics

Connie K. Ho for

While the corruption of Chinese official Bo Xilai and the escape of blind dissident Chen Guangcheng have captured mainstream news headlines, a medical discovery revolving around the air quality at the 2008 Beijing Olympics has recently been publicized. Breakthrough research by the University of Southern California, in collaboration with other campuses, has found biological evidence that links short-term reductions in air pollution to improvements in cardiovascular health.

Their study was based on the $17 billion environmental cleanup, the shutdown of factories, and limitations set on car traffic from July 20, 2008 to September 17, 2008 to encompass the Olympics and Paralympics.

"Air pollution is a risk factor for cardiovascular diseases (CVD), but the mechanisms by which air pollution leads to CVD is not well understood. Hypothesized mechanisms with associated biomarkers include systemic inflammation and thrombosis or endothelial [thin layer of cells that line the heart and certain vessels and cavities within the body] dysfunction," explained the authors in the background information section of the article. "As a condition for hosting the 2008 Olympic Games, the Chinese government agreed to temporarily and substantially improve air quality in Beijing for the Olympics and subsequent Paralympics. This provided a unique opportunity to use a quasi-experimental design in which exposures and biomarkers were measured at baseline (pre-Olympics), following a change in pollution (during-Olympics), and then repeated after an expected return to baseline (post-Olympics)."

The study has been published in this week´s issue of the Journal of the American Medical Association (JAMA) with the theme of global health.

"We believe this is the first major study to clearly demonstrate that changes in air pollution exposure affect cardiovascular disease mechanisms in healthy, young people," noted Dr. Junfeng (Jim) Zhang, senior author  of the study as well as professor of environmental and global health at the Keck School of Medicine of USC, in a prepared statement.

Researchers from the University of Rochester, University of Medicine and Dentistry of New Jersey, and Peking University in Beijing assisted Zhang in his research. Their group of participants consisted of 125 male and female resident doctors who never smoked, were disease free, and worked at a central Beijing hospital. The participants visited the clinic six times: twice before the air pollution controls were instated, twice while the pollution controls were used, and twice after the games had completed.

"Beijing is one of the most polluted cities in the world, and the Chinese government had proposed to reduce pollution levels to be comparable to other Olympic host cities," Zhang commented in the statement. "We wanted to take advantage of such a huge intervention and look at what happens to people biologically."

In the experiment, researchers examined biomarkers for systematic inflammation, blood clotting, heart rate, and blood pressure. During the Olympics, they saw that there were major reductions in Von Willebrand factor and soluble CD62P levels, which are related to blood coagulation, in the participants. However, Soluble CD62P and systolic blood pressure levels increased after the Olympics and these fluctuations show how higher air pollutions levels can heighten the risk for cardiovascular problems.

"Changes in cardiovascular physiology and inflammation contribute to the instability of atherosclerotic plaques, which can lead to a heart attack or stroke if ruptured," Zhang noted in the statement. "The changes in Von Willebrand factor and soluble CD62P are consistent with their roles in rapid thrombotic response."

Few other studies have observed the relationship between the environment and the biomarkers that Zhang studied. According to Dr. Jonathan Samet, a professor and Flora L. Thornton Chair of the Keck School's Department of Preventive Medicine, only recently have there have been population studies that look at the connections between air pollution exposure and the risks of having cardiovascular disease. The study shows the harms that air pollution exposure can have on the general public´s health.

"This study shows how air pollution exposure may act to increase cardiovascular disease risk, supporting the more general findings on air pollution and this very important group of diseases," explained Samet, who also is director of the USC Institute for Global Health. "We need to remember that large numbers of people in cities around the world are still exposed to high levels of air pollution as they are in Beijing."

National Institute of Environmental Health Sciences (NIEHS), the Health Effects Institute, the Beijing Municipal Bureau of Environment Protection and the Beijing Council of Science and Technology provided funding for the study.

"When air pollution levels are lowered, the health benefits can be immediate," remarked Dr. Caroline Dilworth, program administrator from the NIEHS, in a prepared statement.

An article on China´s air quality dilemma of economic versus environmental forces, written by Dr. Francesca Dominici and Dr. Murray A. Mittleman of the Harvard School of Public Health, accompanied the report in JAMA.

"In recent decades, China has achieved industrialization and urbanization. However, China has been much less successful in maintaining the quality of urban air. Several factors challenge the implementation of air pollution controls in China: heavy reliance on coal as a main heating system, especially in subsidized housing; lack of political incentives for trading slower growth for less pollution; economic factors: most Chinese factories and power plants run on extremely thin margins and fines for polluting are generally lower than the cost of controlling emissions; and economic transformation of the landscape, from ubiquitous construction sites to the rapid expansion of the nation's vehicle fleet. If air pollution in China and other Asian nations cannot be controlled, it could spread to other continents. A recent study by Lin et al provides compelling evidence that Asian emissions may account for as much as 20 percent of ground-level pollution in the United States. Clean air is a shared global resource. It is in the common interest to maintain air quality for the promotion of global health,” Dominici and Mittleman wrote in their article.