The result of their study, published today in the Journal of the American Medical Association, shows a direct correlation between pollution levels and specific physiological changes that increase risk for cardiovascular disease.
“This study clearly shows that a large scale intervention to reduce air pollution can have an immediate positive effect on health,” said David Q. Rich, Sc.D., M.P.H., first author of the study and an epidemiologist with the University of Rochester Medical Center Department of Community and Preventive Medicine. “As air quality improved during the games in Beijing, markers of key biological pathways associated with cardiovascular disease also improved, demonstrating that – even in healthy young Beijing residents – there are specific mechanistic links between air pollution and cardiovascular health.”
In the months leading up to and during the 2008 Beijing Olympics (August 8-24) and Paralympics (September 6-17), the Chinese government went to extraordinary lengths to improve the city’s chronic and notoriously poor air quality. This included an aggressive program to curtail traffic and reduce emissions by implementing strict restrictions on automobile and truck use, closing factories, halting construction projects, spraying roads with water to reduce dust, and seeding clouds to induce rain fall. These controls – which were relaxed upon completion of the games – resulted in a significant decrease in the particles and gases associated with air pollution for a period immediately before and during the Olympic games, including a 60 percent reduction in sulfur dioxide, a 48 percent reduction in carbon monoxide, and a 43 percent reduction in nitrogen dioxide.
“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 previous Olympic host cities,” said Junfeng (Jim) Zhang, Ph.D., co-author of the study and a professor at the Keck School of Medicine at the University of Southern California. “We wanted to take advantage of such a huge intervention and look at what happens to people biologically.”
The study specifically examined the relationship between pollution levels and markers of a range of biological mechanisms related to cardiovascular health. The authors measured blood pressure, heart rate, and markers of inflammation and blood coagulation – or clotting – before, during, and after the games in 125 healthy male and female medical residents of Peking University First Hospital in central Beijing. Previous studies have linked some of these measures with the risk of heart attacks, strokes, and other cardiovascular problems.
The authors found that the markers used in the study essentially mirrored pollution changes – improving as anti-pollution controls were implemented and rebounding once the air pollution controls were relaxed. For example, two key indicators of blood coagulation – von Willebrand factor and soluble P-selectin concentrations – were reduced by 13 and 34 percent respectively during the games. After the games, these two indicators returned to near pre-Olympic levels. The study also saw similar, but not statistically significant, patterns of change in blood pressure and white blood cell count during the period of pollution controls.
The authors also point out that while the study was conducted with young and healthy participants the benefits in terms of the risk reduction associated with lower pollution levels may be even greater for older and more vulnerable individuals.
Additional co-authors of the study include: Howard Kipen, M.D., M.P.H., Pamela Ohman-Strickland, Ph.D., Ping Zhu, M.D., Claire Philipp, M.D., Shou-En Lu, Ph.D., Jian Tong, M.S., and Scott R. Diehl, Ph.D. with the University of Medicine and Dentistry of New Jersey; Wei Huang, Sc.D., Guangfa Wang, M.D., Yuedan Wang, M.D., Min Hu, Ph.D., and Tong Zhu, Ph.D. with Peking University in Beijing, and Jincheng Gong, Ph.D. and Duncan Thomas, Ph.D. with the University of Southern California. The study was funded by the National Institute of Environmental Health Sciences, the Health Effects Institute, the Beijing Environmental Protection Bureau, and the Beijing Council of Science and Technology.
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