Researchers have found that airbourne pollution can trigger damage to blood vessels. Ke Wei Gong and colleagues, from the University of California at Los Angeles, culture endothelial cells of the type that line blood vessels with particles from diesel exhaust and oxidised phospholipids of the kind associated with LDL or "bad" cholesterol. The cells were then analysed to study the patterns of genes that had been switched on or off in response to the exposure, compared with unexposed controls. The researchers found the diesel exhaust particles were affecting at least three genetic pathways linked to inflammatory processes in the linings of blood vessels. Next they exposed mice, which had been genetically programmed to develop the rodent equivalent of high cholesterol levels, to the diesel particles. They found the same pattern of altered gene activity in the animals as they had seen in the cell cultures. These results may explain the observed link between heart attacks and strokes and levels of atmospheric pollution, and also highlight a mechanism by which pollution might increase the risk of vascular diseases.