Academic researchers have found that breathing motor vehicle
emissions triggers a change in high-density lipoprotein (HDL) cholesterol,
altering its cardiovascular protective qualities so that it actually
contributes to clogged arteries.
In addition to changing HDL from "good" to
"bad," the inhalation of emissions activates other components of
oxidation, the early cell and tissue damage that causes inflammation, leading
to hardening of the arteries, according to the research team, which included
scientists from UCLA and other institutions.