Unfortunately, there is scant research into the health effects of tire particulates. One of the few comprehensive studies was completed more than a decade ago, in 2012. “At that time, it was not decided that it was the priority subject,” says Gary Guthrie, SVP, Michelin. “The priority subject was more understanding the fate of particles in water and how they degrade.”
“Studies sponsored by the Tire Industry Project (TIP) of the World Business Council for Sustainable Development (WBSCD) have indicated that tire and road wear particles (TRWP) do not pose risk to human health,” says Wanka. “Inhalation studies suggest that TRWP is unlikely to pose risk to humans through airborne exposure.”
“Tire pollution and NOx emissions are different,” says Erlendson. “NOx is a gas byproduct of fuel combustion, while tire particulate matter is a solid pollutant, akin to dust from wood burners. Unlike NOx or CO2 from tailpipes, however, there are no global regulations currently in effect that specifically limit tire pollution.”
Are Biodegradable Tires the Answer?
Biodegradable tires look like a potential solution to tire pollution. However, there are some paradoxes with this idea. “Tires are safety relevant,” says Wanka. “They are the only contact between a vehicle and the road. Hence it is crucial that no degradation of a tire occurs until the end of the use phase.” For many tires, the lifespan could be five years or more.
“While the tire industry is increasingly exploring bio-based materials, such as natural rubber, tires themselves, and the pollution they generate, are not yet biodegradable,” says Erlendson. “A tire that biodegrades on the vehicle would not be good for durability. However, it would be beneficial if the tire particles that shed during driving could biodegrade in the environment, preventing them from accumulating in our air, land and oceans.”
“Our focus is on the front end rather than the back end right now,” says Guthrie. This means using more recycled materials in manufacturing, aiming for a degree of circularity. “What we would prefer to do is to be able to take the tire at the end of its life and make a new one from it, because that is even better for the planet than being able to just put it on flowerbeds. That way, we don’t have to take raw materials out of the Earth to make the tires in the first place.”