United Kingdom – Metal particles released by worn-out brake pads – brake dust – may have the same harmful effects on the immune system as diesel exhaust fumes, according to new research.
Lab tests have shown dust from the component can cause inflammation of the lungs and reduce the ability of immune cells to kill bacteria, increasing the risk of respiratory infections.
The effects of air pollution particles from diesel emissions have been well documented, with studies linking the exhaust fumes to lung cancer, various respiratory illnesses and decreased lung function.
A team from King’s College London now believes brake dust could be contributing not only to endless coughs and colds among city dwellers, but also to more serious illnesses like pneumonia or bronchitis.
Dr Ian Mudway, who led the research at the MRC Centre for Environment and Health at King’s College London, said: “At this time the focus on diesel exhaust emissions is completely justified by the scientific literature, but we should not forget, or discount, the importance of other components, such as metals from mechanical abrasion, especially from brakes.
“There is no such thing as a zero-emission vehicle and as regulations to reduce exhaust emissions kick in, the contribution from these sources are likely to become more significant.”
It is estimated that metal particles from brake wear is responsible for up to a fifth of fine air pollution particles, known as PM2.5, at roadsides.
To test the effects of brake pad particles on human lungs, the team collected dust from a brake pad testing factory and exposed it to a group of immune cells, known as macrophages, in the lab.
Macrophages are the lungs’ front-line defence system which kill bacteria by engulfing and digesting them.
When exposed to particulates from diesel exhaust and brake dust, the researchers found the ability of the macrophages to take up and destroy bacteria was reduced.