CHICAGO (Reuters) -
Air pollution heavy in small particles
may cause blood clots in the legs, the same condition air
travelers call “economy class syndrome” from immobility during
flight, researchers said on Monday.

Dr. Andrea Baccarelli of the Harvard School of Public
Health in Boston and colleagues said they found the link after
looking at 870 people in Italy who had developed deep vein
thrombosis between 1995 and 2005.

When compared with 1,210 others living in the same region
who did not have the problem, they found that for every
increase in particulate matter of 10 micrograms per square
meter the previous year, the risk of deep vein thrombosis
increased by 70 percent.

On top of that, the blood of those with higher levels of
exposure to particulate matter was quicker to clot when tested
at a clinic, they reported in the Archives of Internal
Medicine.

Air pollution from automobiles and industry can contain
tiny particles of carbon, nitrates, metals and other materials
that have been linked over the years to a variety of health
problems.

While lung diseases were an initial concern, later research
has indicated it may cause heart disease and stroke, possibly
because it increases the rate at which blood can coagulate,
Baccarelli and colleagues said.

Until now particulate pollution had not been linked to
blood clots in the veins. The mechanism that causes problems
for some air travelers is related not to the blood itself but
to impaired circulation when sitting in one place without
exercise for long periods of time.

The findings introduce a new and common risk for deep vein
thrombosis, the researchers said and “give further substance to
the call for tighter standards and continued efforts aimed at
reducing the impact of urban air pollutants on human health.”

In a commentary, Dr. Robert Brook of the of the University
of Michigan in Ann Arbor said if the findings are proven by
additional research it may turn out that “the actual totality
of the health burden posed by air pollution, already known to
be tremendous, may be even greater than ever anticipated.”

(Reporting by Michael Conlon; editing by Maggie Fox and
David Wiessler)