We normally associate car brakes with saving lives – but now it seems they could also be causing us some harm.

Researchers writing in BioMed Central’s open access journal Particle and Fibre Toxicology have found that heavy braking, such as in an emergency stop, can release particles that have been shown to harm lung cells in vitro. Even normal braking, and close proximity to a disengaged brake, can result in potentially dangerous cellular stress, according to the findings.

Michael Riediker from the Institute for Work and Health in Lausanne, Switzerland, along with Barbara Rothen-Ruthishauser and Peter Gehr from the University of Bern, Switzerland, worked with researchers to study the effects of brake particles on cultured lung cells placed in a chamber close to the axle of the car. 

They stated that brake wear contributes up to 20 per cent of total traffic emissions but the health effects remain largely studied. Now they have found that the metals in brake wear particles can damage junctions between cells by a mechanism involving oxidative stress.

The analysis suggests that brake wear particles contain large amounts of iron, copper and organic carbon. Exposure to these pollutants can cause oxidative stress and inflammation. The researchers hope that further studies will determine which components are involved in each cell-stress pathway and stated that efforts to diminish these emissions will improve ambient air quality and help protect human health.