London, Nov 21 (IANS) Tiny particles released by car brake pads can harm lung cells, according to new research.

Researchers found that heavy braking, as in an emergency stop, caused the most damage, but normal breaking and even nearness to a disengaged brake resulted in potentially dangerous cellular stress.

Mechanics Barbara Rothen-Rutishauser and Peter Gehr from the University of Bern and Michael Riediker from the Institute for Work and Health, Lausanne, worked with a team of researchers to study such effects.

'Brake wear contributes up to 20 percent of total traffic emissions, but the health effects of brake particles remain largely unstudied. We've found that the metals in brake wear particles can damage junctions between cells by a mechanism involving oxidative stress (OS),' the authors said.

OS denotes the steady-state level of oxidative damage in a cell, tissue, or organ, caused by the reactive oxygen.

The teams' analysis revealed that brake wear particles contain considerable amounts of iron, copper and organic carbon.

Exposure to these pollutants caused increased signs of oxidative stress and inflammation in the cells, and hard braking caused most exposure, said a Bern release.

Interestingly, some exposure still occurred even when the brakes were not being applied, presumably due to residual brake particles coming off the turning axle and the braking system.

These findings were published in the journal Particle and Fibre Toxicology.