When you think of traffic pollution, what comes to mind? Exhaust fumes? What about miniscule pieces of tyre rubber floating around in the atmosphere?

Tyre wear particles make up a significant portion of air pollution in UK cities and is only projected to increase over the next decade. In fact, it is estimated that about 1.3 million tonnes of these fine particles are released into the environment across Europe each year – that’s the same as 620 London Eyes! These particles can be around a tenth of the width of a human hair so are easily inhaled and pose a potential risk to our health.

Despite making up a large portion of air pollution across the country, and indeed the world, this ‘tyre dust’ is difficult to detect and distinguish from other pollutants in the air, which makes monitoring levels and assessing any potential health risks challenging. The ideal situation would be identifying a way to trace tyre pollution levels using detectors that are already used to monitor air quality.

Researchers at the MRC Toxicology Unit, along with collaborators at the Department of Engineering at the University of Cambridge and the National Physical Laboratory, set out to find a way to identify polluting tyre particles in air samples that contain a mixture of particles.

Tyre rubber is a complex mixture of chemical elements, and their composition can vary due to the make and model, or even whether the tyre is destined for a car, bike, or lorry. Thus, the most suitable and reliable chemical elements to trace and monitor specifically for tyre pollution is debated.

Using samples from new, undriven tyres from several manufacturers, so that the rubber was uncontaminated, the researchers analysed 25 different elements to generate a profile of which chemicals are the most abundant. They revealed that zinc was the most common element, followed by aluminium, iron and magnesium.

This important fingerprint of tyre rubber is a vital new piece of evidence that will be submitted to an EU database and provide researchers and air pollution scientists with crucial information about the composition of tyres currently being used on our roads, how much they are polluting our air and the amount that humans may be exposed to.

‘Multi-element analysis of tyre rubber for metal tracers’ was published on 20th June in the journal Environment International. Read the full publication here.