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2-stroke scooter more damaging to the environment than a lorry

Scooters said to produce hundreds of times more “organic aerosols” than larger vehicles, according to new study.

Bad news if you thought a scooter was better for the planet. Scientists from the University of Cambridge have discovered your average two-wheeled, 2-stroke runabout gives off more damaging “organic aerosols” than just about anything else on the road.

Death by scooter
Death by scooter

The study revealed a 2-stroke scooter spews out 2.5g of organic aerosols per kg of fuel when idling and 2g when driving ─ 277 times less than an idling diesel lorry made before 2009 and 625 times more than one made after. Also emitted is 3g of benzene when idling and 0.6g when driving.

A diesel car made before 2009 was found to emit 0.02g of organic aerosols per kg of fuel when idling and 0.06g of benzene. A 2-stroke rickshaw was the most polluting in the study, at 5g per kg of fuel.

Such is the level of pollution, the report warned being behind a scooter “may be highly deleterious to health”. It helps little that reactive oxygen is another by-product, which has been linked to lung damage.

There are two reasons a scooter is such a smog-creator. Firstly, a 2-stroke engine is much less effective at burning fuel, which means the exhaust fumes contain higher traces of organic aerosols and volatile organic compounds. Secondly, the exhaust system is less effective at removing harmful pollutants compared with a catalytic converter you get in a four-wheeled vehicle.

“We showed that, in contrast to the general belief, scooters can be a dominant source of air pollution, including soot and organic particles, in urban areas. We showed that the particles transformed the atmosphere from these scooter emissions are especially toxic,” University of Cambridge scientist Markus Kalberer told the Telegraph.

Even though less than one per cent of EU fuel is used in scooters, the report said reducing the number of 2-stroke scooters on roads would have a big impact on air pollution levels. Seven Chinese cities have, in fact, already brought a ban into place, with a noticeable drop in pollution observed each time.

Scooters have come under scutiny before. A report published in the Nature Communications journal said 2-stroke scooters accounted for 60 per cent of roadside pollution – even though they account for just 10 per cent of total fuel consumption.

“Our data suggest that 2-stroke scooters are a significant, and in many cities, the largest source of vehicular particular matter and toxic secondary organic aerosols and aromatic hydrocarbons, despite being a relatively small fraction of the total fleet,” the report said.

“Therefore, given the alternative technologies available, restrictions on two stroke scooters, already implemented in China, could improve air quality in many cities around the globe,” it concluded.

Certain countries already restrict the use of older 2-stroke outboard motors on boats because of their inefficiency and amount of fuel they dump into the water. It’s worth pointing out that newer 2-stroke engines are more efficient than their aging counterparts.

So there you have it. The UK government should forget imposing 60mph speed limits to improve air quality and ban scooters instead. Much less inconvenient, if you ask us.

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