The system involves a new type of concrete that contains steel shavings and carbon particles.

These chemicals coat the outside of tiny carbon particles emitted by diesel cars.

Past work has shown that the carbon particles can be drawn deep into the lungs, but it was not known whether they were themselves problematic.

If this simulation reflects the movement of carbon particles from engine exhausts, we have even more reason to urgently reduce air pollution.

While smaller particles are readily transported by the lubrication system, larger carbon particles may abrade components with close tolerances.