When zero emissions are not truly zero emissions
While governments are keen to facilitate the mass adoption of battery electric vehicles (BEVs), recent research from King’s College and Imperial College London reveals that more needs to be done to improve air quality. Yet, combustion engines are not the focus.
The UK’s Air Quality Expert Group states that non-exhaust vehicle emissions (from tyres, road surfaces and brake linings) contribute half of all particulate pollution from road transport. However both colleges state that dust from brake pads is responsible for 20% and these are particles small enough to find their way deep into lungs.
While brake pads have not contained asbestos since the 1990s, heavy metals feature in friction linings, including iron and copper. These are reputed to damage cells, when they build within a living organism. The colleges highlight that the risk of lung infection was increased, in their experiments.
Interestingly, it was found that these particulates are at their highest concentration around road speed bumps, reflecting the tension between organisations that believe speed humps are crucial to road safety and the National Institute of Clinical Excellence (NICE), which has suggested that they should be removed/redesigned to cut pollution.
Even so, brake dust pollution is not being ignored by the car parts industry, with a number of quality manufacturers removing certain heavy metals from their friction compounds, although they admit that more work needs to be done. Interestingly, MANN+HUMMEL released details of a brake dust filter last year, which attaches directly to the caliper and traps brake dust as it is generated. To date, we are unaware of a new car that has them fitted as standard-equipment.