So, you thought that smoke spewing from vehicle exhaust pipes are the worst polluters making air thick with smog and smoke dust dirtying the environment? Guess again, tyres are the leading highest polluter of water resources and leaching of chemical compounds from tyre wear and tear are found in air, water, and soil samples posing a huge threat to marine life.
Microplastics is a term commonly used to describe extremely small pieces of plastic debris in the environment resulting from the disposal and breakdown of products and waste materials. The EU-Commissioned research paper ‘Plastics in the Marine Environment’ found that tyres were the main single cause of marine microplastics, amounting to 270 million tonnes per annum and as an analogy if we melt enough Arctic snow to get about 3 liters of water, “it might contain as many as 53,000 pieces of microplastic.”
Tyres on vehicles are made from a complex blend of different materials and chemicals including several types of plastic in addition to their rubber base. Every time we brake, accelerate our vehicle, or turn a corner, tyres spew microplastics with the average car tyre losing a total of 4kg of plastic throughout its lifetime due to wear. These particles become airborne affecting our lungs and ending up in our waterways and oceans eventually entering our food chain. It’s estimated that we eat about a credit card’s worth of plastic every week .
Wear and tear of tyres by country:
Calculating wear and tear can be approached in a few ways, by using emission factors per vehicle-km multiplied by the total mileage or by gauging the number of tyres multiplied by the weight loss of these tyres during use.
Looking at data from countries such as China, India, Australia, the USA and Brazil on the amount of wear and tear emitted into the environment, data on mileage and number of vehicles, below are some findings:
India has the lowest wear and tear estimate, i.e., 0.23 kg/capita/year, while the USA has the highest, i.e., 4.7 kg/capita/year. The 20-fold difference can partly be explained by the fact that USA has 0.82 cars per capita, while in India there are 0.13 cars per capita. Car density in India is only 16% of that in the USA. The amount of wear and tear per vehicle in the USA is 6.8 kg/year compared to 1.8 kg/year for India, a 3.8-fold difference. Americans are leading in wear and tear emissions because they have more vehicles while they also travel longer distances per vehicle, especially with their trucks(lorries). China at 0.55 kg/capita/year, Australia at 0.87 kg/capita/year and Brazil at 1.4 kg/capita/year are comparable estimates. Other countries data can be found here in this paper.
In India and China, the number of vehicles per capita are lower which explains the lower emission per capita per year.
Do new Electric Vehicles (EV) make this better?
Electric vehicles are 24% heavier than their conventional counterparts and so tyre wear and tear would be higher. But new technologies in braking such as regenerative braking in electric vehicles reduces usage of brakes and pads and the big tyre brands and companies are specifically working towards reducing pollution from tyres.
We can use nature’s tools to clean up urban rivers and other waterways and estuaries that bear the brunt of the micro plastic pollution and improve water quality by restoring fragile ecosystems.
Scientists are focusing on organisms like bivalves (such as oysters and mussels) and aquatic plants (such as celery grass, eel grass beds) to cleanse the water. Bivalves and aquatic vegetation improve water clarity by arresting suspended particles, allowing more light to penetrate deeper. They also have an exceptional capacity to cycle nutrients — both by absorbing them as food and by making them more available to other organisms. Thriving underwater plant meadows act as carbon sinks absorbing heat and provide food and habitat for small fish, crabs, and other bottom-dwellers.
Riparian buffers are strips of vegetation (trees, shrubs, or grass) planted next to streams or other waterbodies. These spaces are planted with native species of water tolerant trees and large shrubs and filter pollutants such as microplastics before entering the water.
In Conclusion: As individuals, we can reduce tyre footprint by choosing to walk, cycle or share vehicles, buy smaller cars, driving carefully, avoiding high-speed braking, and using public transport systems, but with a growing population and expanding infrastructure there needs to be a broader approach to microplastic pollution problems.
Tyre materials contain natural rubber tree latex as well as synthetic rubber polymers and switching to natural latex would lead to expansion of rubber trees and further deforestation. Rubber plantations need huge volumes of water to grow, with Thailand, Indonesia, Malaysia, and India the top rubber producing countries in the world grappling with natural plantation degradation. It is a consumption-based problem that needs responsible consumers and sellers who consciously switch to ‘sustainable’ rubber. And our community has to come together and implement nature-based solutions to proactively protect our water bodies across ecosystems and build climate resilience.