Hardening of the Arteries Linked to Air Pollution

Nino Kunzli MD, PhD; Frank Gilliland, MD, PhD; Duncan Thomas PhD, and John Peters, MD
Keck School of Medicine
University of Southern California
P30ES07048 and P01ES11627

Background: Thickening of the lining of the carotid artery is a marker of early hardening of the arteries or atherosclerosis. Arterial vessel wall changes occur during a presumably long lag phase characterized by a gradual thickening of the arterial lining; however, the clinical symptoms of heart disease often do not arise until the stage of advanced atherosclerosis. Previous research supported by NIEHS and conducted by this and other groups of investigators has shown associations between long-term exposure to air pollutants and heart disease. Oxidative stress leading to inflammatory responses has been proposed as one reason for the resulting disease. However, studies have not been performed investigating possible links between air pollution and the development of atherosclerosis which usually precedes many cardiovascular diseases. To address this issue, this team of scientists at the Keck School of Medicine at the University of Southern California reviewed data from a previous epidemiologic study on 798 people to investigate the association between atherosclerosis and long-term exposure to ambient particulate matter, a component of air pollution.

Advance: The arterial linings of the highest particulate matter exposed group were 12.1% thicker than the lowest exposed group. The associations between exposure and arterial lining thickening were stronger for older subjects, for women, for persons taking lipid-lowering medications, and for people who had never smoked. These differences translate into a 3-6% increase in the long-term risk for heart attack.

Implications: This study presents the first evidence for an association between exposure to ambient air pollution and the development of arterial changes that lead to atherosclerosis. Because atherosclerosis is a complex disease, it would be premature to say that particulate matter and its constituents are the cause of the disease. However, given that heart disease is the leading cause of death in the United States, if these findings are confirmed, they may prove to be of high public health importance.

Citation: Kunzli N, Jerrett M, Mack WJ, Beckerman B, LaBree L, Gilliland F, Thomas D, Peters J, Hodis HN. Ambient Air Pollution and Atherosclerosis in Los Angeles. Environmental Health Perspectives; doi:10.1289/ehp.7523. Online 22 November 2004.