Picture: Magnified particles of microscopic pollution 
A particle of microscopic pollu-
tion, magnified 2,000; 10,000
times; © Vinayak P. Dravid

Microscopic pollution particles spew from the exhaust of diesel trucks, buses and coal-burning factories. Up to now scientists only knew that the particles -- too small to be filtered by the nose or mouth -- caused inflammation of the lungs. But what was the link between particles trapped in the lungs to the strokes and heart attacks.

Researchers from the Northwestern University’s Feinberg School of Medicine have discovered that this microscopic air pollution – smaller than ten microns or less than one-tenth of the diameter of a human hair -- spurs hyperclotting of the blood. The study found that lungs inflamed by the pollution secrete a substance, interleukin-6, which causes an increased tendency for blood to coagulate or clot. This raises the risk of a fatal heart attack or stroke in people with cardiovascular disease such as coronary artery disease, congestive heart failure or a history of stroke.

People at risk can probably help protect themselves by taking low-dose aspirin to keep their blood thin, Gokhan Mutlu, M.D., lead author of the study and assistant professor of pulmonary and critical care medicine at the Feinberg School, and a physician at Northwestern Memorial Hospital said.

In the study, the researchers used particles of pollution mixed them into a saline solution and injected the pollution cocktail into the lungs of mice. The blood of the mice exposed to the pollution clotted faster than mice not exposed. Researchers observed a 15-fold increase in interleukin-6, 24 hours after the mice were exposed to the pollution. In people, interleukin-6 also raises the levels of a substance called CRP, which is correlated with death from cardiovascular disease.

Particulate matter pollution is highest near expressways or truck routes. The only safe location with lower levels is indoors. Exercising hikes the risk because it floods the lungs with more polluted air.

MEDICA.de; Source: Northwestern University