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16-05-2012 | Cardiology | Article

Tackling air pollution for Beijing Olympics affected CV risk markers


Free abstract

MedWire News: Reductions in air pollution levels during the Beijing Olympics in 2008 were associated with improvements in cardiovascular physiology in healthy young people living in the city, researchers report.

"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 cardiovascular disease (CVD)," report Junfeng Zhang (University of Southern California, Los Angeles, USA) and team.

Aggressive pollution-control measures were implemented during the Olympics, they say, providing the opportunity to study whether markers related to CVD pathophysiologic pathways are sensitive to air pollution.

The authors measured daily pollutant levels as well as C-reactive protein (CRP), fibrinogen, von Willebrand factor, soluble CD40 ligand (sCD40L), and soluble P-selectin (sCD62P) concentrations, white blood cell count, heart rate, and blood pressure (BP) in 125 healthy adults (mean age 24 years) living in Beijing before, during, and after the 2008 Olympics.

The concentration of particulate and gaseous pollutants, including sulfur dioxide, carbon monoxide, nitrogen dioxide, elemental carbon, organic carbon, and sulfate, decreased substantially by between 13% and 60% from before the Olympic period (June 2‑July 20) to during the Olympic period (July 21‑September 24).

There were statistically significant reductions in sCD62P levels by 34.0% from a pre-Olympic mean of 6.29 ng/mL to a during-Olympic mean of 4.16 ng/mL. Levels of von Willebrand factor also improved significantly, falling by 13.8% from 106.4% to 92.6%.

After adjusting for multiple comparisons, changes in the other biomarker outcomes were not statistically significant.

In the post-Olympic period (September 25‑October 31), when pollutant levels increased, most levels returned to approximately pre-Olympic levels, but sCD62P and systolic blood pressure significantly worsened from the during-Olympic to the post-Olympic period, the authors say.

The fraction of above-detection-limit values for CRP (percentage ≥0.3 mg/L) was reduced from 55% in the pre-Olympic period to 46% in the during-Olympic period and reduced further to 36% in the post-Olympic period.

Zhang et al note that interquartile range increases in pollutant concentrations were consistently associated with statistically significant increases in fibrinogen, von Willebrand factor, heart rate, sCD62P, and sCD40L concentrations.

"Overall, the pollutant-biomarker associations provide further mechanistic support that the biomarker changes across the Olympic periods were acute inflammatory and prothrombotic responses to changes in air pollution," they say.

In a related commentary, Francesca Dominici and Murray Mittleman, both from Harvard University, Boston, Massachusetts, USA say that Zhang and team's 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."

"Clean air is a shared global resource," they add, saying that in view of the study's findings, "it is in the common interest to maintain air quality for the promotion of public health."

By Piriya Mahendra

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