Beijing Olympics Air Pollution Change Impacted On People's Health

A study featured in the May 16 edition of JAMA shows that changes in air pollution during the 2008 Beijing Olympics were related to changes in biomarkers of systemic inflammation and thrombosis, in addition to measure of cardiovascular physiology in healthy young people.

The study's background information states:

"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.

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)."

David Q. Rich, Sc.D., of New York's Rochester University, and his team decided to perform a study to examine whether markers linked to CVD pathophysiological pathways, i.e. biomarkers for systemic inflammation and thrombosis, heart rate and blood pressure are sensitive to changes in air pollution.

The team took daily measurements of air pollutants and measured various biomarkers, including heart rate and blood pressure in 125 healthy young adults before, during and after the 2008 Olympics, i.e. from June 2 until October 30. The various biomarkers included measures linked to systemic inflammation, such as fibrinogen, C-reactive protein [CRP] and white blood cell [WBC] count, as well as thrombosis or endothelial dysfunction, i.e. platelet activation markers P-selectin [sCD62P] and soluble CD40 ligand [sCD40L], and the adhesive endothelial glycoprotein von Willebrand factor.

The team noted that the concentrations of particulate and gaseous pollutants dropped significantly from -13% to -60% from the pre-Olympic to the during-Olympic period. The reductions during this period were noted as an average concentration of sulfur dioxide (-60%), carbon monoxide (-48%), nitrogen dioxide (-43%), elemental carbon (-36%), PM2.5 (-27%), organic carbon (-22%), and sulfate (-13%) from the pre-Olympic to the during-Olympic period.

The researchers state:

"In contrast, ozone concentrations increased (24 percent). Pollutant concentrations generally increased substantially from the during- to post-Olympic period for all the pollutants (21 percent to 197 percent) except ozone (-61 percent) and sulfate (-47 percent)."

Statistically, important improvements were noted in SCD62P levels by -34.0%, and in the von Willebrand factor by -13.1%. After adjusting for multiple variables, the changes in other outcomes did not prove to be statistically important.

The researchers noted that when pollutant concentrations increased in the post-Olympic period, most outcomes averaged pre-Olympic levels, aside from the sCD62P levels and systolic blood pressure levels, which were substantially worse than compared with the during-Olympic period. In a concluding statement the researchers write:

"The fraction of above-detection-limit values for CRP was reduced from 55 percent in the pre-Olympic period to 46 percent in the during-Olympic period and reduced further to 36 percent in the post-Olympic period. Interquartile range increases in pollutant concentrations were consistently associated with statistically significant increases in fibrinogen, von Willebrand factor, heart rate, sCD62P, and SCD40L concentrations. Although these findings are of uncertain clinical significance, this study provides quasi-experimental, mechanistic data to support the argument that air pollution may be a global risk factor for CVD."

Editorial: China's Air Quality Dilemma - Reconciling Economic Growth With Environmental Protection

In an associated editorial, Francesca Dominici, Ph.D., and Murray A. Mittleman, M.D., Dr.P.H., from Boston's Harvard School of Public Health write:

"China's dilemma, like many countries with emerging industries, is how to reconcile rapid economic growth with environmental protection. 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."