Tiny Air Pollution Particles Hurt Heart

Jan. 18, 2008 -- The tiniest air pollution particles may be particularly bad for heart health.

A new study links ultrafine particulates from traffic to worse atherosclerosis (hardening of the arteries) in mice.

Ultrafine particulates "may constitute a significant cardiovascular risk factor," write Jesus Araujo, MD, PhD, of the University of California at Los Angeles (UCLA), and colleagues.

Their findings appear online in Cardiovascular Research.

Effects of Air Pollution

Araujo's team studied air pollution and atherosclerosis in a mobile lab near a Los Angeles highway.

The researchers piped outside air into the lab, filtering it to varying degrees for three groups of mice.

One group of mice breathed air laced with ultrafine particulates. A second group breathed air containing ultrafine and larger particulates, with fewer particulates overall in that air. The third group breathed air free of particulates.

Particulate levels for the mice that breathed the dirty air were two to six times higher than inside a typical car on a Los Angeles highway, Araujo's team notes.

The study lasted for 40 days. During that time, mice breathing air that only contained ultrafine particulates developed the worst atherosclerosis.

Tiny Particulates, Big Impact

The mice that also breathed bigger particulates also got atherosclerosis, but it wasn't as severe. The mice that breathed the filtered air containing no particulates had the healthiest arteries.

Diet can also affect atherosclerosis. But all of the mice got the same food, so that wasn't the problem.

Ultrafine particulates also hampered HDL ("good") cholesterol from fighting inflammation, the study shows.

Araujo and colleagues call for further studies to see if the findings apply to people.