Tyre wear a significant source of airborne microplastics
A lot of focus on microplastic waste is to prevent plastic going into our environment. Tyres consist of a mix of elastomers such as rubber (natural and synthetic), carbon black, steel cord, fibres, and other organic and inorganic components used to improve their stability. Tyre wear particles are produced by shear forces between the tread and the road pavement, generating coarse particles, or by volatilization generating submicronic particles. The wearing process depends on the type of tyre, road surface and vehicle characteristics, as well as on the vehicle’s state of operation. This Nature paper by a Evangeliou et al (2020) has calculated how much Tyre Wear particles are being released annually into our atmosphere and where it is transported to.The authors estimate an annual continental emission of TWP in the size of PM2.5 to be around 5.8 kilotonnes in Europe, and worldwide around 29 ktonnes. This opens up an interesting question: are microplastics implictly regulated in the PM10-PM2.5 standards that are set by WHO and countries around the world?