Posts Tagged ‘Diesel Pollutants’

Why diesel cars are bad for our health

Broadcast on Today with Sean O’Rourke [24-08-2016]

Diesel Smoke

Tiny particles of soot pollution from diesel cars and vehicles have been linked with cancer and life-threatening lung diseases (source:

Tax incentives for those buying diesel cars over the last decade has fueled a move to diesel on Irish roads, with diesel cars now outnumbering petrol cars.

This has been widely regarded as a welcome move, as diesel cars are considered ‘better for the environment’ because they produce less carbon dioxide gases than petrol cars – the gases that have been linked with causing global warming.

However, scientific evidence is emerging which shows that the level of diesel particulates, which are damaging to human health, has increased in line with the growing popularity of diesel and that Irish people are dying as a result of this. The European Environment Agency has, for example, estimated that 1,200 people in Ireland per year are dying as a result of diseases caused by particulate pollution.


Until relatively recently, there has not been a significant amount of research into the impact of diesel pollution on public health, particularly in Europe, but the Volkswagen diesel emissions scandal certainly gave it an added push.

The evidence that is emerging from the US primarily – where research has been going on for longer – suggests that there is real reason for concern when it comes to health effects, and environmental effects, or air pollution from diesel engines. The US Environmental Protection Agency (EPA), the World Health Organisation and the UK Department of Transport have all produced reports in the last year or two which point to a real problem here.

As well as pointing to increased emissions of particulate matter (PM) and Nitrogen Dioxide gas, which are known to damage human health, the authorities in Europe and the US have started to make a direct link between an increase in numbers of people dying from respiratory diseases and cancers, and this increase in pollution.

The US EPA, who support a lot of work in this area, has led the way with publication of figures of increased numbers of premature deaths, cancers and respiratory diseases due to air pollution from diesel vehicles. There is a tangible link, a ‘smoking gun’ if you link that is linking cause and effect.


There has been little research into subject in Ireland until this year. In January 2016, a research project began at Trinity College Dublin, with funding from the Irish EPA, which is looking to precisely determine the amount of a certain type of damaging particulate, called PM 2.5 which is produced by diesel vehicles here.

It is a multi-disciplinary research effort, involving experts in air pollution, chemistry and transportation and will take place over 24 months. At the end of it, they say they will be able to determine precisely, using computer software modeling, how many deaths and illnesses here are caused by diesel vehicles.

One of the researchers involved, Dr Bidisha Ghosh, is a transportation expert, and said that the plan is to look at diesel particulates first, and to then to a follow up study where the impact of NO2 is measured and assessed.


The Irish EPA has a number of monitoring sites around Ireland that will be used as measuring points. One of the key challenges – and this is the first time anyone in the world has done this – will be to distinguish the percentage of PM 2.5 (particulate matter 2.5, a size of particulate) that is from diesel cars as opposed to other potential sources, such as sand, or the burning of coal.

The measuring sites will be near to roads as that is where diesel fumes are strongest, and another part of the study will determine how quickly dangerous diesel pollution dissipates as you move away from a busy road.

The researchers will be looking closely at what comes out of the diesel particulate filters that are attached to diesel cars. This is in order to get the chemical composition, or signature of PMs to better identify those PMs that are from diesel cars or other diesel vehicles. This is a difficult task and will involve using specialised machines to look at tiny quantities of polluting chemicals.

Dr Ghosh said that by the end of their project, in the latter part of 2017 they will be in a position to give precise numbers on the health effects of the growing use of diesel cars in Ireland. At that stage, she said they will have precise numbers on how many extra deaths, or premature deaths are being caused or what kind of extra number of lung cancers and other respiratory diseases are happening in Ireland due to us driving more diesel cars.

The calculations are based on knowledge of the car fleet, the type and age of cars on Irish roads, and knowledge of what the standard pollution emission from a certain vehicle of a certain age will be. This makes it possible to do comparison such as comparing the 2000 level of emissions versus the 2015 levels and matching the increase in pollution with the increase in deaths and diseases.

The project will also make it possible to predict, based on a number of scenarios – such as increasing use of diesel cars at the current rate – what Ireland can expect in 2020 or 2030 in terms of death rates from air pollution. This, it is hoped, will produce a solid basis for policy makers to address this problem.

Diesel cars 

The new new diesel cars on the market have very good particle filters and if you are sitting inside one of these cars you wouldn’t get a whole lot of this PM pollution, and the newer models may not pollute the atmosphere that much. The old diesels is where the big problem lies, and there are still a lot of old diesel cars being driven on Irish roads today, as they have vastly inferior emissions control technology to more modern cars.

It is also true that the bigger diesel car engines are far more polluting. The researchers at TCD, who have access to pollution figures in Ireland between 2010 and 2015 said there was a very significant increase in diesel PMs in those years, and this finding was what prompted a more detailed air pollution study.

The researchers also strongly suspect that the VW scandal wasn’t just a VW issue, and that many other diesel car makers have been cooking the books, in the sense that the emissions reported in the car manual does not bear much resemblance to the real on road emissions. The real figures, I was told, are likely to be far, far higher than what we see in the new diesel car manuals.


The Irish government started to actively support diesel from 20o8, with various tax incentives, in order to help Ireland meet its carbon dioxide ‘greenhouse gas’ targets. In fairness to the Irish government back then, the extent of the public health risk from diesel cars was not widely known.

It was initially thought that certain types of PMs were not harmful, but that thinking has changed, and now scientists are looking at the damage caused by diesel particulates that can remain wedged in the lungs. For example, the particulate, PM 1, is very hard to remove from the lung once in.

The evidence that is now emerging, however, is that not only is diesel bad for public health, it is also, by producing NO2, bad for the environment.

The science around this is all still quite new, and emerging. It is only in 2015 that a report was published by the UK authorities which stated that NO2 can also be very harmful to children, their respiratory development, their lung development and that it can cause irreversible changes.

The initial findings about the problem with diesel took time to emerge, as they didn’t perhaps fit with the green image of diesel, especially in Europe. However, the more research on this that is being done, the clearly the scientific picture becomes, and eventually, governments will have to act on the results.


Nitrous oxide, and nitrous dioxide gases from diesel cars and vehicles are also linked with health problems, and the data can be collected again by using standard emissions and examining the national car fleet. This is likely to be supported by specific EPA funded research in future, which will, like the TCD project looking at PMs, look into NO2 levels at certain EPA monitoring sites, near busy roads around the country.

Aside from being linked with respiratory disease and death, NO2 is known to have a negative impact on vegetation and acts to break down the ozone layer.


There are emerging fuels out there, such as hydrogen gas, which is being made available at existing petrol stations in the UK this summer.

However, experts believe that because the infrastructure and global distribution network is built for diesel and petrol cars, and that huge investment has been made in this system, that it will be impossible to envisage a change to any other fuel or transport type in the near, or even distant future.

Electric cars are still rare in Ireland despite significant government support, as people don’t like some of the unanswered questions that remain on it, such as how long does an electric car last, and what to do should a battery die out?

There is also the fact that a very high amount of energy can be liberated from diesel or petrol, and there is nothing that can rival petroleum on that score.

The solution, some suggest, is to truly move towards a sustainable transport system, where people walk if they can, and only use a car when they have to. Those countries that do this, and that promote public transport have far less emissions from petroleum car engines. It is also very important to think about where we locate our busy roads, as studies have shown that irreversible damage can be done to schoolchildren from air pollution in schools near such roads.

For those that need a car, the advice is to look at getting rid of the old diesel and replacing it with a new one, with better a particulate filter. Also, to avoid buying one of the high performance diesel cars and go for a more modest option.

There is also the issue in Ireland of people removing diesel particulate filters when they start to affect car performance. They can be expensive to replace, and some garages in Ireland are openly offering services on the internet to remove and not replace the filters.


A diesel car can run without a filter, and not replacing a malfunctioning filter can save hundreds if not a few thousand euros. However, from a public health and environmental perspective removing a filter is “disastrous, really, really bad” according to Dr Ghosh.

Actively preventing the removal of diesel particulate filters from diesel cars, and insisting on a high standard of operation of diesel filters as part of the NCT test, might be how the Irish government might start trying to tackle this important public health issue.


The diesel engine – a nineteenth century invention – remains the world’s most widely used engine, but does it have a future?

Click above to listen to discussion on the diesel engine, past, present and future, above on Today with Sean O’Rourke

Click above to listen to discussion with Ann-Marie Donelan, presenter of The Grapevine show, on CRC 102.9 FM

The diesel engine was designed more than a century ago, yet it remains the engine that, more than other, powers our 21st century world.

The diesel is used everywhere from mines, cars, trains, ships and lorries, yet it has changed little since it was invented by Rudolf Diesel in 1892.

There are many remarkable aspects to the  history and development of the diesel, still the world’s favourite engine.

VW Passat Diesel

A Volkswagen Passat CC car is tested for its exhaust emissions at a testing station in London (Credit: John Stillwell/PA)


Diesel engines are in the news because it is a diesel engine that is at the heart of the Volkswagen pollution emissions scandal, which is still playing out.

The background to the scandal is the tightening restrictions by the US, the European Union and others on emissions of certain gases in cars.

There is a dual demand on car manufacturers to produce cars that perform well, run smoothly, are fuel efficient, and ‘clean and green’.

Car manufactures must deliver both, because if they don’t, they their cars will be taxed heavily, and people don’t want to buy ‘dirty’ cars.

The problem is, according to some engineers, that our law-makers were essentially asking VW and the other car makers to do the impossible.

We can’t have our cake and eat it, the engineers say. We can either have clean, green, fuel efficient cars, or we can have high performing cars, we can’t have both.

People buy diesel cars in particular, because they want to buy a car that is cheaper to run, reliable, fuel efficient, and performs well.

The noose has been tightening around the necks of VW and others because the regulations on emissions have been steadily tightening.

At some point, a decision was obviously made that the only option – faced with the impossible – was to cheat the regulator’s tests.

It was relatively easy to cheat the tests, as EPA car tests in the US are standard, and done on machines. Who else is doing this we must ask?

Diesel Engine 1906

A 1906 diesel engine built by MAN AG (Source: Wikipedia)

How does a Diesel engine work?

Diesels work by converting chemical energy in diesel fuel into mechanical energy which is put to use by the engine.

The energy in diesel is released following an uncontrolled explosion when it comes into contact with very hot, pressurised air.

This ignition, or explosion occurs when diesel, which has first been atomised is sprayed by fuel injection into the compressed air.

This creates energy which initially drives a linear motion, up and down, of a piston, which is transferred to a rotary motion of the crankshaft.

Because the diesel ignition is uncontrolled, it is not smooth like a petrol engine, and the cylinders must be contained inside a heavy engine block.

The energy from the ignition pushes the piston down, inlet valves open, and fresh air is allowed into the engine from the outside.

The diesel engine effectively takes an ‘in breath’.

When the energy is expended, the piston moves up again, the ‘second stroke’ of the engine, and the fresh air is compressed.

The inlet and exhaust valves are closed so that the air cannot escape and is compressed. The temperature and pressure of the air rise to a value that is higher than the self-ignition value of the diesel.

This means the diesel ignites immediately on contact with the pressurised air. The air is circulated by a bowl (during the compression stroke) at the top of the piston which ensures an even spread of fuel.

Each engine cycle requires two strokes, breath in, and breath out if you like. However, many diesel engines are four stroke so that the energy produced is more evenly spread, and there is less shaking.

There are different amounts of energy produced by the uncontrolled explosion of diesel via each stroke. The more strokes, the more even the energy spread.

In a four-cylinder engine, with 4 driving pistons, there can be 4 power strokes happening at the same time, so the power stroke is always present in the engine.

The more cylinders a diesel engine has, the smoother it will operate. A heavy flywheel (timing belt) also helps to smooth out non uniformity of power, as do various weights applied to the crank shaft.

The operation of a diesel engine is all about producing high temperature and high pressure air continuously.

GERMANY - JUNE 06: In 1892 Rudolf Diesel (1858-1913) patented a design for a new type of internal combustion engine. In 1897 he produced a 25 horsepower, four-stroke, single vertical cylinder compression engine, the high efficiency of which, together with its comparative simplicity of design, made it an immediate commercial success. Subsequent royalty fees brought great wealth to its inventor. He was lost overboard from the mail steamer 'Dresden' during a trip to London in 1913 and was assumed to have drowned. (Photo by SSPL/Getty Images)

Rudolf Diesel, the inventor of the diesel engine (Source: Wikipedia)


It was invented by German engineer Rudolf Diesel, who took out patents on a diesel engine in 1892 and 1993.

Diesel became famous and successful very quickly, as his engines went into production all around the world.

In 1897 the American brewery magnate Adolphus Busch acquired a license to make the machine for about one million marks, or about $50,000.

Soon the Busch Diesel engines were being built in the USA and Canada for locomotives, factories and ships.

Diesel now became primarily a salesman for his engine, and he moved with family moved into a palatial mansion in Munich.

From there, he spent much of his time taking legal action to prevent patent applications, by other engineers seeking to improve on his engine.

This cost him a lot of time and nervous energy. It was mostly a waste of his effort, as he wasn’t usually successful. in court.

Overworked, stressed by patent trials, and pressurised by his family’s expensive lifestyle, Diesel got sick, and his fortune was gobbled up, without his knowledge.

When he became aware that his fortune was gone, it took it very badly. In 1913, Rudolf Diesel vanished from the ferry, the S.S. Dresden, as she sailed to England.

The date of his death is marked in his diary by a cross. Suggests Diesel chose to take his own life by suicide.

Diesel versus petrol 

Diesel fuel is far less refined than petrol. It is a mixture of hydrocarbon molecules produced by the distillation of crude oil.

Petrol is far more explosive, and will light instantly when a match is put to it. Petrol is volatile even at room temperature and lets off fumes, and the vapour is flammable, so it is a dangerous fuel to have in an engine.

Diesel engines are based on a design where fuel is atomised and sprayed onto a compressed chamber of air, which results in small explosions.

This provides a lot of power potentially, but it is also means that the engine can be subject to shaking, and needs a hard body to contain it.

The petrol in petrol engines are ignited by spark plugs which light a fuel that has been highly refined and premixed before entering the engine.

The petrol engine, because it uses a more refined fuel, and because its ignition is less explosive, tend to be smoother running than diesel.

Both engines convert chemical energy present in the fuel into mechanical energy, which does useful work in driving the pistons up and down.

Diesel engines are better at converting more chemical energy into useful work, so they are said to be more efficient engines with less energy loss.

So, in most petrol engines, petrol and fuel are pre-mixed before being compressed. This was done in the ‘old days’ by a carburetor, but in cars today there is electronically controlled fuel injection.

In a diesel engine, the fuel is injected into very hot air, which has been compressed, at the end of a compression ‘stroke’ and self ignites.

Diesel is a thicker, heavier fuel than petrol, which works best in an engine going at a constant speed, and can solidify at low temperatures.

Big Diesel Engines

The world’s biggest and most powerful engines, like this one built for a supertanker, are invariably diesel engines (Source:

Why is the diesel so important ?

Diesel is crucial because it is the workhorse of industry. Diesel engines are reliable, powerful and safe, as they don’t use flammable fuel.

They are used everywhere, particularly where a lot of power is required such as trains, boats, lorries, submarines and tractors.

They are also used in cars, where they are touted to provide power, performance, as well as low emissions of pollutants.

No other engine still today is so versatile and is used in so many applications. The vast majority of the world’s commercial, industrial , agricultural, mining and military vehicles are diesel powered.

It is remarkable that a 19th century invention is still the most important engine in the world in the 21st century. Diesel engines power the world.

What kind of pollutants do diesel engines emit? 

Diesel exhaust emissions contain toxic air contaminants some of which listed as cancer-causing.

Diesel cars, emit around 20 times more so called NOx (nitrogen oxide and nitrogen dioxide) as a result of their combustion design, than petrol engines, as well as small amounts carbon monoxides.

NOx is formed when nitrogen and oxygen from the air are combined – under heat and pressure. More heat and pressure gives you more NOx.

Diesel also contains sulphur, which can be hazardous to human health. Exposure to diesel particulate matter (or dpm, such as soot particles)

The US Environmental Protection Agency (EPA) says that even short term exposures to NO2, of 30 minutes, can result in airway inflammation in healthy people, and worse effects for those with asthma.

Exposure to NO2 linked with increased visits to A&E for respiratory issues. NO and NO2 are together often referred to as NOx and both are potentially harmful.

People living near roadways have been shown exposed to 30 to 100% higher concentrations of NO2 than those living away from roads, the US EPA says.

When nitric oxides are subject to heat and sunlight they react with volatile organic compounds to produce Ozone, which is also linked with all kinds of respiratory problems.

What did the ‘real world’ tests on VW diesels show up?

The hidden damage from these 11 million VW vehicles affected could equate to all of the UK’s NOx emissions from all power stations, vehicles, industry and agriculture.

The EPA tests have known practices and profiles. In many cases, the test vehicles are put on rollers and run at a certain speed for a certain time, then at another known speed for another known period.

The car’s central computer can detect whether inputs match those expected in test conditions.

A non governmental agency, the International Council on Clean Transportation (ICCT), performed independent – and crucially on-road – emissions tests, on the VW Passat, the VW Jetta, and a BMW X5.

The Jetta was found to be emitting up to 35 times the allowable limit of nitrogen oxide and the Passat up to 20 times.

These tests followed five routes on similar lines to the EPA simulations: highway, urban, suburban and rural up/downhill driving.

The emissions performance of the Volkswagen, but not the BMW, cars was so much worse than expectations that the ICCT ran further tests on a dynamometer.

In these circumstances, the cars passed with flying colours. It was at this point that the ICCT contacted the EPA.

Merdes Bens Diesel

The first diesel powered car was the 1936 Mercedes Benz 260D (Credit: Zoltan Glas)

How has the engine improved over the years?

Before World War 1, submarines were built with diesel engines, which were not as flammable and dangerous to the submariners.

After World War 1, where the diesel was widely used, the engine was adapted for an increasing number of peacetime usages.

The first big improvement was the move away from the cumbersome air blast injection system for diesels.The fact that a large compressor had to be attached to the engine prevented it being used in many situations.

Then in the 1920s, engineers developed. something called the Jerk type pump. This pump measured out a  precise amount of fuel to be delivered as a spray to the engine at the precise moment it was required.

This fuel injection technology got rid of the need for an air compressor, and allowed for smaller, lighter diesels to be built and widely used.

Only on the roads, was the diesel engine slow to come in, and it was not until 1924, that MAN and Daimler Benz built the first diesel lorry.

It took even longer, until 1935, until the first diesel powered car appeared, the Mercedes Benz 260D.

The traditional design for the diesel engine was too noisy and heavy for road vehicles. However, in the late 20 century that engineers gave diesel cars better ‘road manners’.

Achieving this, however, was, it the expense of the environment. The more efficient combustion of diesel engines meant that the soot particles in diesel car exhausts became smaller and smaller, and more harmful to health since they could be inhaled more easily.

Engineers came up with a particle filter under the car, which collects and burns the soot particles. This type of filter is used in race cars and light aircraft.

The diesel became the engine of choice for military equipment on the ground and at sea during World War 11.

After the war, it was adapted for use in construction machinery, large tractors, most large trucks and buses.

Ultra-reliable diesel engines came into use in hospitals, telephone exchanges, and airports to provide power during power outages.

What happens if I put gasoline into a diesel engine?

Diesel in a gasoline engine will not even cause ‘firing’ because diesel is less volatile and will not mix with the air properly-sparking will not initiate combustion.

But, if you put gasoline in a diesel engine, you are putting a highly volatile fuel into a chamber of highly compressed and hot air.

This will lead to detonations, rather than smooth combustion, and eventually the engine components can get damaged!

Why is it so hard to develop clean diesel engines?

Diesel fuel is full of long hydrocarbon chains, and a gallon of diesel fuel contains more energy than a gallon of petrol.

The problem is that when diesel is burned in an uncontrollable way it is hard to control the waste products, which often include sulphur.

The old diesel cars, such as the 1979 Oldsmobile in the US spewed lots of tiny sulphur-containing particles into the air.

These days diesel car makers are good at trapping this kind of emission and the use of ultra-low sulphur diesel fuel helps.

However, it has proved more difficult for car makers to deal with the NOx gases, NO, NO2, and NO3.

These form at naturally at high temperatures, which are essential for a diesel engine to work. The react with sunlight and form ozone, which is O3.

Ozone is an irritant and bad for human health. It makes our yes water, our throat hurt, worsens asthma and causes heart problems too.

Diesel cars produce far more NOx than petrol cars.

The problem for engineers is that the temperatures and pressures under which a diesel engine runs best (in terms of pep and fuel efficiency) are also the conditions which will convert the maximum amount of oxygen and nitrogen into NOx.

With spontaneous ignition of diesel it’s not easy to keep track of what compounds have formed, and then to clean them up.

Also, it should be noted that in Europe, where about half of all cars run on diesel, there is less regulatory focus on NOx than greenhouse gases.

Does the Diesel engine have a future?

Many engineers believe the diesel has a bright future. It’s an engine that can run on peanut oil, and other biodiesels as Diesel himself showed.

There is no cheaper or more environmentally form of power today than combining a diesel engine with plant oil. If eco fuels catch on, it will be the final fulfillment of Rudolf Diesel’s dream.

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