The results of the study, which the authors believe is the first major study to clearly demonstrate that changes in air pollution exposure affect cardiovascular disease mechanisms in healthy, young people, appear in the Journal of the American Medical Association.
“We already know that when air pollution is higher people suffer more acute heart and lung conditions such as heart attacks and strokes,” said Dr. Howard Kipen, one of the study’s co-authors and the interim chairperson of the Department of Environmental and Occupational Medicine at UMDNJ-Robert Wood Johnson Medical School. “This study demonstrated mechanisms in blood that are thought to underlie how air pollution could actually trigger such clinical events. While we did not observe actual heart attacks in our subjects, the fact that they were healthy and young, and showed reversibility of the changes when pollution improved, strengthens the evidence for taking primary public health actions to reduce air pollution.”
Beijing, plagued by chronic air pollution, was awarded the 2008 Summer Olympics after promising to improve air quality for the duration of the event. The Chinese government spent $17 billion on environmental cleanup, shut down factories and limited automobile traffic from July 20 to Sept. 17 to encompass the entire Olympic (Aug. 8-24) and Paralympic (Sept. 6-17) games. Pollution control measures relaxed after the Paralympics.
The research team, which also included scientists from the UMDNJ-School of Public Health, UMDNJ-New Jersey Dental School, University of Southern California, University of Rochester and Peking University in Beijing, recruited 125 male and female resident doctors who worked at a central Beijing hospital, all of whom were never-smokers and disease-free. The participants, whose average age was 24, visited the clinic six times: twice prior to the air pollution controls, twice while the pollution controls were in play and twice after the games had ended.
The researchers examined biomarkers for systemic inflammation and blood clotting, as well as heart rate and blood pressure. During the Olympics, they observed statistically significant reductions in Von Willebrand factor and soluble CD62P levels, both of which are associated with blood coagulation, among the study participants. Soluble CD62P and systolic blood pressure levels also increased significantly after the Olympics.
“Changes in cardiovascular physiology and inflammation contribute to the instability of atherosclerotic plaques, which can lead to a heart attack or stroke if ruptured,” said Junfeng (Jim) Zhang, PhD, the study’s senior author and a professor at the Keck School of Medicine of the University of Southern California. “The changes in Von Willebrand factor and soluble CD62P are consistent with their roles in rapid thrombotic response.”
These changes indicate that exposure to higher air pollution levels are associated with an increased risk for cardiovascular problems. Each biomarker observed in the study has been related to cardiovascular morbidity or mortality in clinical studies, but few studies have considered how the environment affects the markers. Changes among other measured indicators that support this association were also observed, although not statistically significant.
The study underscores the fact that people’s health and the environment are indelibly linked, says Caroline Dilworth, Ph.D., program administrator from the National Institute of Environmental Health Sciences (NIEHS), which provided funding for the study.
“When air pollution levels are lowered, the health benefits can be immediate,” Dilworth said.
The study was jointly funded by the NIEHS, Health Effects Institute, Beijing Municipal Bureau of Environment Protection and Beijing Council of Science and Technology.
The University of Medicine and Dentistry of New Jersey (UMDNJ) is New Jersey’s only health sciences university with more than 6,000 students on five campuses attending the state’s three medical schools, its only dental school, a graduate school of biomedical sciences, a school of health related professions, a school of nursing and New Jersey’s only school of public health. UMDNJ operates University Hospital, a Level I Trauma Center in Newark, and University Behavioral HealthCare, which provides a continuum of healthcare services with multiple locations throughout the state.