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The new era of air pollution

Zero-emission vehicles on the road, powered by electric, hydrogen and solar - this is the future. We also associate this with the idea of clean air, quiet vehicles and healthy and green cities. But with futuristic mobility comes a new era of air pollution. And it is still completely unregulated.

In recent weeks and months, criticism of electric cars and alternative fuels has been growing louder. The hybrid has long been seen as a sham, as it is often bought with subsidies and then driven as a combustion engine after all. But electric vehicles are also criticised, for example, because of their consumption of resources and their (still) low longevity.

Now, however, more and more voices are being raised that attach a completely unimagined, even downright grotesque problem to the new green mobility. The vehicles marketed as zero-emission vehicles harm people and the environment - because they emit too many emissions into the air and the ground.

These emissions are not exhaust emissions caused by the combustion process, they are tiny particles caused by physical friction of vehicle parts, especially brakes and tyres, but also their counterpart, the road.

It has been known for a long time that particulate matter is not only emitted into the environment through the exhaust. As electric vehicles are becoming heavier and heavier because of their ever-larger batteries, and the exhaust emissions of the engine are actually getting smaller and smaller in the case of the latest Euro 6 vehicles with diesel and petrol engines, the abrasion emissions, also called non-exhaust emissions (NEEs), are already causing a large part of the particulate matter emissions of the transport sector. The electric car as a panacea, is not regulated regarding these emissions. In 2019, NEEs accounted for 60% of airborne PM2.5 and 73% of PM10. This huge share is no wonder when you look at the results of recent research by the UK Air Quality Expert Group (AQEG). According to this, the emissions from a tyre - even under extreme loading and driving conditions - are more than 1000 times higher than the emissions from the exhaust, namely 5.760mg/km caused by NEEs compared to 4.5mg/km caused by the combustion engine.

A tyre is mostly made of rubber, which is first of all of plant origin. About 25 components and 12 different rubber compounds are then incorporated into the tyre to create a plastic that has the required properties of the tyre. The abrasion of the plastic when driving is indeed an important property. Without the tyre's grip on the road, a vehicle would fly off a bend much more easily. Over the lifetime of a tyre, about 4 years, the tyre loses about 6 kilograms of the plastic.

Therefore, the latest findings of a research group at Cornell University in the United States of America are not surprising. They have shown that enormous amounts of microplastics are released into the air and soil through the abrasion of tyres. A full 84% of atmospheric microplastics enter the air through road dust. 11% is released via sea spray. In the sea, there are certainly the usual microplastic sources such as packaging and plastic articles, but the microplastic entering the soil and waters from the road is also ultimately released back into the air via the sea in a large cycle.

The Fraunhofer Institute for Environment, Safety and Energy Technology has published the latest figures on microplastics and confirmed that tyres account for the largest share of microplastics in the Earth's ecosystem. Cars, trucks, motorbikes, bicycles and skateboards produce a total of 1,228.5 grams of microplastic waste per capita every year. Cars account for the largest share of this, with 998.0 grams per capita per year. This figure is enormous: per capita, almost 1 kilogram of microplastic is emitted into the environment through tyres every year.

It is therefore high time for politicians to introduce a limit value for NEEs. This applies to both fine dust and microplastics. This is the only way to create an incentive for industry to develop tyres and filter systems that reduce NEEs. Otherwise, the new vehicles would not solve the old problem of emissions, but only perpetuate it in a different way. The way e-cars are currently developing, they do nothing to improve the air we breathe or reduce microplastics in our soils and oceans.

If environmental zones took NEES into account, even the newest electric and hybrid vehicles would not be allowed to enter European environmental zones. A diesel car with Euro 4 standard, for example, may only emit 0.025 grams of particulate matter per kilometre. The tyre's abrasion of 5.7 grams per kilometre is thus significantly higher. Euro 4 is still permitted in Germany, but in other countries, such as Belgium, England, the Netherlands and France, only Euro 5 or 6 vehicles are allowed in some environmental zones. For these Euro standards, the maximum fine dust pollution is 0.0045 grams per kilometre.

So how can it be that tailpipe emissions are so heavily regulated and still no laws have been passed for limit values for NEEs. The EU has a duty to change this urgently. Without this law, the move away from internal combustion engines does not seem to have been thought through. Of course, NEES also exist in combustion cars. But especially with electric cars, the trend is towards much more weight due to the heavy batteries. Many people also like to buy a hybrid or e-SUV or a luxury limousine, perhaps because they think that these are emission-free anyway. So the small city car as it used to be popular is becoming rarer and rarer in the electric version.

Only when tyres become more durable, or are made of more natural materials, or special filters reduce emissions directly at the source, could the idea of clean vehicles become a reality.