Long-term exposure to pollution may speed up hardening of the arteries contributing to heart attacks and strokes, say US researchers.

The researchers, led by Dr Sara Adar from the University of Michigan and Dr Joel Kaufman from the University of Washington , examined how exposure to fine particle pollution affects the carotid arteries — the arteries that supply the head, neck and brain with oxygenated blood.

They found higher concentrations of fine particulate matter (PM2.5) were linked to a faster rate of thickening, while reductions in exposure to fine matter particulates were linked to slower progression of the condition, they report in PLoS Medicine .

“Our findings help us to understand how it is that exposures to air pollution may cause the increases in heart attacks and strokes observed by other studies,” says Adar.

Fine particulate matter (PM2.5) — particles with a diameter of less than 2.5 micrometres or 1/30th the width of a human hair — is mainly produced by motor vehicles, power plants, and other combustion sources.

It has been long been thought that there is a link between exposure to these particles and cardiovascular disease, but previous studies have proved inconclusive.

To examine the link in more detail, the researchers studied 5,362 people aged between 45 to 84 years old from six US metropolitan areas as part of the Multi-Ethnic Study of Atherosclerosis and Air Pollution (MESA Air).

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