When the Chinese government agreed to temporarily and substantially improve air quality in highly polluted Beijing for the 2008 Summer Olympics, researchers saw a unique opportunity to study air pollution effects on biomarkers linked to cardiovascular disease. What they found was that reductions in certain air pollutants during the Olympics were associated with decreased levels of various biomarkers linked to inflammation and blood clotting. After the games ended, both air pollution and these biomarkers rose to pre-Olympic levels.
The findings, which appear today in a global health theme issue of JAMA, are based on a study of 125 healthy young medical residents at a central Beijing hospital who were each tested between June 2 and October 30 in 2008, before, during, and after the games. Junfeng (Jim) Zhang, PhD, the corresponding author and a professor of environmental and global health at the University of Southern California in Los Angeles, discusses his team’s findings:
“There have been a lot of epidemiology studies showing a connection between cardiovascular mortality and morbidity with increased air pollution levels, but we do not know how air pollution affects the heart. So this study tries to understand how air pollution affects young and healthy hearts. Inflammation biomarkers and blood-clotting biomarkers, which are activation markers, rose with pollution levels [following completion of the games]. That explains how air pollution affects cardiovascular health very quickly, because these were acute effects.
“In this study, we focused on mechanistic air pollution effects on the heart in young healthy people, but we did not quantify the risk. So if there is a next study, it would be useful to use more clinically relevant measures and maybe do so in people more sensitive to heart risks than young healthy people.
“Many people in the general public would not think air pollution is a big concern for young and healthy people. Even in the scientific world, we look at mortality and say it is driven by older people who already have cardiovascular disease: pollution only makes their condition worse. But our study shows that high air pollution levels in Beijing, which is not uncommon, affects young and healthy hearts and does so within a few weeks.”