Nano, or ultrafine, particles are the size of a virus or molecule, about one-thousandth the size of a human hair. The Environmental Protection Agency does not regulate particles in the nano or ultrafine range.
The nanoparticles from vehicle emissions may be the most damaging because they cause plaque buildup in the arteries that increases the risk of a heart attack and stroke, according to the study posted in the online edition of Circulation Research journal.
Researchers from the University of California Los Angeles (UCLA), the University of Southern California, the University of California, Irvine and Michigan State University contributed to the study headed.
"It appears that the smallest air pollutant particles, which are the most abundant in an urban environment, are the most toxic," said lead author Dr. Jesus Araujo, assistant professor of medicine and director of environmental cardiology at the David Geffen School of Medicine at UCLA. "This is the first study that demonstrates the ability of nano-sized air pollutants to promote atherosclerosis in an animal model," he said on the UCLA website.
