Changes in air pollution levels during Beijing Olympics linked to alterations in biomarkers

Issue: August 2012

During the 2008 Beijing Olympics, healthy young adults experienced acute changes in biomarkers of systemic inflammation and thrombosis and measures of CV physiology that were due to alterations in air pollution levels.

A study by David Q. Rich, ScD, of the University of Rochester, New York, and colleagues was conducted to determine whether markers related to CVD pathophysiological pathways are sensitive to changes in air pollution.

“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,” researchers wrote in the Journal of the American Medical Association study.

Daily measurements were conducted in 125 healthy young adults from June 2 to Oct. 30, 2008. Biomarkers measured included those associated with systemic inflammation (fibrinogen, C-reactive protein, white blood cell count) and thrombosis or endothelial dysfunction (platelet activation markers P-selectin, soluble CD40 ligand and adhesive endothelial glycoprotein von Willebrand factor), according to a press release.

Changes over time

From the pre-Olympics to post-Olympics period, concentrations of particulate and gaseous pollutants decreased substantially from –13% to –60%. During this period, there were reductions in average concentrations of sulfur dioxide, carbon monoxide, nitrogen dioxide, elemental carbon, PM2.5, organic carbon and sulfate. Ozone concentrations increased by about 24% and pollutant concentrations increased substantially for all pollutants except ozone and sulfate from the during- to post-Olympic period, researchers said.

Among the healthy young people studied, researchers found significant improvements in soluble P-selectin (sCD62P) levels (–34%) and von Willebrand factor (–13.1%; P<.001 for both). Changes in other outcomes were not significant after adjustment for multiple comparisons. After the Olympics, pollutant concentrations increased and most outcomes were back to pre-Olympics levels. Only sCD62P and systolic BP were “significantly worsened” from during the Olympics. In addition, the fraction of above-detection-limit values for CRP (percentage ≥0.3 mg/L) were reduced during the study period (55% pre-Olympics, 46% during-Olympics; 36% post-Olympics). Interquartile range increases in pollutant concentrations were associated with significant increases in fibrinogen, von Willebrand factor, heart rate, sCD62P and sCD40L concentrations, the researchers wrote.

Worldwide implications

Rich and colleagues said these data “are of uncertain clinical importance” regarding the link between air pollution and CVD risk.

In an accompanying editorial, Francesca Dominici, PhD, of the department of biostatistics, and Murray A. Mittleman, MD, DrPH, of the department of epidemiology, both at the Harvard School of Public Health, said, “This study brings new data and evidence regarding air pollution and its health effects in one of the most rapidly developing and polluted cities in the world with a complex political and economic landscape. Nearly two-thirds of the estimated 800,000 deaths and 4.6 million lost years of healthy life worldwide caused by exposure to urban air pollution in 2000 occurred in the developing countries of Asia, including China.

“Clean air is a shared global resource. It is the common interest to maintain air quality for the promotion of global health,” Dominici and Mittleman wrote.

The 2012 Olympic Games will take place in London from July 27 to Aug. 12.

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Disclosure: The researchers, Dr. Dominici and Dr. Mittleman report no relevant financial disclosures.