QU: Hundreds of thousands, if not millions, of car tyres are worn down on roads every year. What effect do the tons of rubber dust have on the Earth and on us?
Everyone knows that cars are bad for the environment – of course they are – we love to bemoan the rate at which they consume our rapidly declining stocks of fossil fuels. It’s rare, however, that you find people blaming the tyres, normally we only notice them when one is looking a little flat. Perhaps this needs to change; research indicates that pollution from tyre dust is linked to an expanding range of health problems including allergies, asthma and even heart disease!
The problem is that what goes into a tyre eventually comes out as the tread wears down. And what goes in? The list of ingredients is not as simple as rubber from a rubber tree! To form the rubber into hard-wearing vehicle tyres, an extensive range of chemicals including xylene, benzene, petroleum naphtha, chlorinated solvents, polycyclic aromatic hydrocarbons, anthracene, phenanthrene, phenols, amines, oil, acids and alkalis, polychlorinated biphenyls, halogenated cyanoalkanes, processing aids, and plasticisers. Tyre processing also involves several heavy metals including zinc, cadmium, lead, chromium and copper.
Argh! It gets worse; as you drive, tiny fragments of this cocktail of ingredients break off creating a particularly insidious form of air pollution known as tyre dust or particulate matter.
Until recently scientists working for the Environmental Protection Agency (EPA) thought that tyre dust didn’t present a threat to humans because the particles are too small to enter our lungs. But in the last decade studies have shown that about 60 per cent of the fragments can enter the very deepest parts of the human lung and cause damage. In areas of high traffic tyre dust can cause asthmatic attacks and pose a serious threat to the elderly, babies and young children. More worryingly tyre dust has now been linked to heart disease and diabetes.
The impact of tyre dust on human health is undeniable. So it is particularly frustrating that there appears to be no immediate answer to, or recognition of the problem. In fact relatively little data exists to quantify the emission rates, size, distribution and composition of particulates from tyre wear. When government think-tanks talk about tyres, they generally focus on waste disposal, this is undoubtedly important, but clearly its scope is woefully inadequate.
It’s time that the bigger picture of tyre lifecycles is examined so we can begin to reduce their impact on health and environment. In the meantime you can reduce your car’s contribution to the dust by ensuring it’s tyres are inflated to the proper level and correctly balanced, keeping your speed down and making sure you don’t overload it. Even better you can leave the car in the garage and hop on your bike – wearing your safety dusk mask of course!