Most people will now be aware of the terms ‘Climate Change’ and ‘Global Warming’, and of the link to Carbon Dioxide (CO2) emissions from the burning of fuel. Many people will also have heard of the Volkswagen (VW) diesel “emissions scandal”, where VW cars are fitted with engine management software that ensures that when emissions testing is carried out the engines produce far lower emissions than when the vehicle is in normal daily use on the road. Only this week (July 19th 2017), Mercedes have also owned up to similar practice, issuing notices to owners of their diesel cars to bring them in for engine software modification. Other car manufacturers have issued similar statements since the VW story emerged. There are now multi-million dollar lawsuits in progress on both sides of the Atlantic as a result of this. All over the world, air quality is increasingly seen as very important, so how did we get into the present impasse?
Beginning in around 1990, people were actively encouraged to purchase cars with diesel-engines because diesel fuel burns more efficiently than normal petrol, thereby emitting less carbon dioxide via the exhaust. In an international effort to reduce CO2 emissions many governments around the world sought to reduce these emissions by lowering the taxes on diesel fuel to encourage people to buy diesel cars. They have succeeded to the extent that just over half of all cars in the UK are now diesel-powered. However, the current problem arises from the fact that CO2 is not the only emission from diesel engines, they also emit a lot of tiny aerosol sized (1 micron down to I nanometre diameter) particles, which are too tiny to be visible and which are easily inhaled. These particles are of oxides of nitrogen and of carbon black (soot). Because they are so tiny, they do not quickly settle out, and can remain airborne for hours and days. It is these tiny particles that are the cause of current concern. Note that while cars with petrol engines emit more CO2 they do not produce the harmful oxides of nitrogen and carbon black that diesels do. In the meantime, manufacturers of petrol engines have made them considerably more efficient, further eroding the perceived advantage of diesels. So it is specifically diesel engine emissions that cause this problem.
These fine particles are known to exacerbate problems with asthma and can cause respiration difficulties, and also be a causal factor in heart attacks, strokes and lung cancer. There is special concern about the effects on young children who may be exposed to them, as diesel fumes are particularly harmful to babies and young children whose lungs and respiratory systems are still developing. Therefore a lot of diesel-powered vehicles outside school gates with engines running can very quickly cause a local pollution ‘hot spot’ where levels of particulates can reach way beyond what is deemed to be safe for humans, and especially children, to breathe. The air quality in many large cities falls well below ideal levels, and a good deal of this is attributed to diesel fumes.
What can we do?
- If possible, walk your children to school
- If you have a diesel car, and run children to school, do not leave the engine running while you drop them off.
- If you have a diesel car, do not leave the engine running outside supermarkets, bus stations, rail stations or anywhere where you have to wait for any length of time.
- When you change your car, get one with a petrol-engine, or better still, a hybrid. These are becoming more available and affordable
John Sturges j.sturges@leedsbeckett.ac.uk;
Julia Hyliger julia.hyliger@hotmail.com;