Numerous studies have shown that increased levels of air pollution are positively associated with cardiovascular illness and death. Although most studies have focused on the influence of systemic effects triggered by the impact of pollution on the lungs, a new review published in the 26 August issue of the Journal of the American College of Cardiology (JACC) highlights that ultrafine particles may be translocated into the circulation and directly transported to the vasculature and heart where they can injure the heart and blood vessels, increase rates of hospitalization for cardiac illness, and can even cause death.
Particulate pollution is categorized into three main classes: coarse particles with aerodynamic diameter (AD) 2.5 to 10 µm (PM10); fine particles (AD <2.5 µm; PM2.5), and ultrafine particles (AD <0.1 µm; UFPs). PM10 particles related to human activities come from numerous sources including road and agricultural dust and tire wear emissions. Fine particles are mainly generated by gas to particle conversions and during fuel combustion and industrial activities. The primary contributors to UFPs are tailpipe emissions from mobile sources (motor vehicles, aircraft, and marine vessels).
“We used to think air pollution was a problem that primarily affects the lungs. We now know it is also bad for the heart,” said Robert A. Kloner, M.D., Ph.D., director of research at the Heart Institute of the Good Samaritan Hospital, and a professor of medicine at the Keck School of Medicine, University of Southern California, both in Los Angeles.
When pollutants are inhaled, they trigger an increase in reactive oxygen species that damage cells, cause inflammation in the lungs, and spark the cascade of harmful effects in the heart and cardiovascular system.
However, recent research highlighted in the JACC paper suggests that ultrafine air pollutants, such as those coming from car exhaust, may pass into the blood stream and damage the heart and blood vessels directly. Hearts directly exposed to ultrafine air pollutants show an immediate decrease in both coronary blood flow and the heart’s pumping function, as well as a tendency to develop arrhythmias, according to studies conducted at the Heart Institute of the Good Samaritan Hospital in Los Angeles, California.
There doesn’t have to be an environmental catastrophe for air pollution to cause injury. We’re talking about very modest increases. Air pollution can be dangerous at levels that are within the accepted air quality standards.—Boris Z. Simkhovich, M.D., Ph.D, Heart Institute and Keck School of Medicine
Boris Z. Simkhovich, Michael T. Kleinman, and Robert A. Kloner (2008) Air Pollution and Cardiovascular Injury Epidemiology, Toxicology, and Mechanisms. J Am Coll Cardiol, doi: 10.1016/j.jacc.2008.05.029