Ultrafine Particles and PM Health Effects — A Review
Heart disease is the leading cause of death and hospitalization among older adults. Numerous community health studies have reported positive and consistent associations between cardiovascular hospital admissions and mortality with outdoor air pollution, particularly measures of PM2.5 and PM10.
Panel studies have also reported positive associations between PM and risk of cardiac ischemia and arrhythmias, increased blood pressure, decreased heart rate variability, and increased markers of inflammation and clotting in the blood.
This review study focuses on ultrafine particles, those less than 0.1 microns, which dominate particle number concentrations and surface area, and are therefore capable of carrying large concentrations of adsorbed toxic air pollutants to cardiovascular target sites.
The article reviews epidemiologic, panel, and experimental studies of cardiovascular effects. Though most of these studies used measures of PM2.5 or PM10, reviewers hypothesize that it is the ultrafine fraction that may be the causal agent leading to a cascade of acute cardiovascular responses.
“High UFP [ultrafine particle] exposures may lead to systemic inflammation through oxidative stress responses to reactive oxygen species, and thereby promote the progression of atherosclerosis and precipitate acute cardiovascular responses ranging from increased blood pressure to myocardial infarction,” state the authors.
They propose that components in ultrafine particles from fossil fuel combustion reach target sites in the lungs, veins, and heart to induce inflammation and oxidative stress, and suggest that future research focus on PM causal components and size fractions.
Delfine RJ, Sioutas C, Malik S. Potential Role of Ultrafine Particles in Associations between Airborne Particle Mass and Cardiovascular Health. Environ Health Perspect 2005; 113:934-946.
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