Dossier: Emissions of NOx in 7 questions and answers, why is this so dangerous pollutant? Why is so severe the Volkswagen case?

In motor long ago we set out to direct our editorial line towards a very specific focus: to uncover the myths of diesel, explain how the industry faced new environmental concerns, and how it would be determined by the technology of our cars, especially diesel. And we try to do it from the point objective as possible, without unreasonable phobias with a series of articles that have reached hundreds of thousands of readers. The case of Volkswagen has put into question the environmental diesel and reopens the debate and the model approval cycles. Those responsible for this whole thing are the NOx. And at this point we ask, why are so dangerous these contaminants? What is the relationship with the diesel? Finally, why is so serious Volkswagen scandal? talk about all this guide NOx 7 questions and answers about the case.

1. What is NOx?

Though the rulers and public opinion focused all their attention on the CO 2 and the gases responsible for the greenhouse effect, the NOx is one of those most responsible for the high pollution in our cities and create serious health problems.

NOx is the nomenclature used to encompass all gaseous compounds formed by the chemical combination of oxygen and nitrogen. When we speak of them in this context, we do talk mainly of nitric oxide (NO) and nitrogen dioxide (NO 2 ). Although the scientific community, and our rulers, have put the focus mainly on greenhouse gases (especially CO 2 ) for their global implications, NOx are so damaging, or more, if possible. They have very serious health consequences.

The reason for simplifying encompassing all low NOx compounds makes sense. We speak of highly polluting compounds generated by the hand of man, and not produced (such as CO 2 ) by natural processes, usually by combustion processes, such as occurring in combustion engines our cars or boilers of heating our homes.

These combustion emissions primarily generated NO, that from other processes is oxidized and becomes NO 2 and NO 3 . These compounds, after passing through other processes, are also precursors to other pollutants such as ozone, of which I will discuss later.


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2. What are the implications for health?

are especially harmful to children, the elderly and chronically ill, creating and aggravating respiratory, eye and cerebrobasculares diseases.

In its Air Quality Guidelines, warning World Health Organization (WHO) of the serious consequences that a very high concentration of nitrogen dioxide for our health. Own WHO acknowledged that there is a solid basis for finding direct effects of prolonged exposure to these pollutants, although there is evidence to cause concern. Some epidemiological studies have shown that symptoms of bronchitis in asthmatic children increase in association with the annual concentration of NO 2 and the smallest increase in lung function of children is linked to high concentrations of NO 2 .

It is also shown that short-term exposure to high concentrations of NOx can now generate very harmful health effects such as irritation of the respiratory and ocular systems, and worsening, or onset of chronic respiratory diseases and cerebrobasculares.

Children, the elderly, and people with health problems (such as asthma, heart disease and lung) would be most affected by high concentrations of NOx. A high concentration of NOx in the measurement centers of a city, at least, is to trigger a public warning and recommendations as outdoor sports.

The NOx also contribute to water acidification, the phenomenon known as acid rain.


3. What is considered a high concentration of NOx?

In cities like Madrid in 2014 were far exceeded some of the NOx pollution limits imposed by the European Union.

In our cities there are systems capable of measuring concentrations of certain greenhouse gases, following the recommendations of WHO and European standards. The current limits in the European Union, from which it is considered that there is a significant problem of contamination is established based on the limits set by the WHO . Speak of mean concentrations in a given period of time, 40 g / m3 average annual and 200 g / m3 of half an hour. Exceeding those limits requires communicate the problem to the population; if the case is severe, establish traffic restrictions or take action – often strong – to tackle the problem; and even heavy fines for cities that exceed these limits with repetition.

Although the concentrations of NOx in Madrid have declined in recent years, did you know that 6 of the 24 measuring stations in Madrid exceeded the annual average of 40 ug / m3 in 2014? Beyond the ideological overtones of the parties that governs and has governed in the Spanish capital – in which we will not go in. – Pollution is a problem that governments have to tackle, maybe even exceptional measures and drastic

The NOx are partially responsible for the toxic cloud, colloquially known as beret, covering the city of Madrid many days. A cloud that usually do not see when we are inside a city, but it contributes to a picture, sometimes grim, sometimes bucolic, the skyline of the city when we approach it from the outside .


4. Why NOx are usually associated with diesel?

The combustion of diesel generates the perfect breeding ground for NOx. NOx emissions from diesel are much higher than those of gasoline engines, hence the Euro VI came into play to limit NOx emissions.

There are numerous studies on the subject, with figures also vary, but as a rule come to very similar conclusions. Over the last two decades, European regulations led to a considerable reduction in particulate emissions, which is related to combustion, but has to do strictly with the NOx. Instead, it was found that between Euro 3 and Euro V vehicles standards in Europe had reduced NOx emissions ever so slightly (see report in The ICCT ), the fleet had continued to grow, and the problem of pollution in cities had worsened. That was the reason that led to the introduction of a very strict Euro VI NOx standards.

The combustion of diesel engines is the perfect place to maximize the generation of NOx place. The conditions of temperature and pressure under which works a diesel engine makes the NOx emission right is much greater than that emitted by gasoline engines. A study by the Madrid City Council in 2009 concluded that diesel passenger cars emit, on average, three times more NOx and specifically 29 times more NO2 per kilometer than a car of gasoline.


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5. How can we get rid of the NOx?

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With the fledgling Euro VI regulations, and a focus on NOx the industry had to be prepared to tackle the problem as soon as possible. To beat the NOx, or at least drastically reduce their concentration, enough to overcome future emission regulations, manufacturers used different solutions based on pretreatment, post-treatment, combustion modification and process. In general, each manufacturer has sought the most cost effective solution to meet their interests, without going into too much detail will tell you the most common.

brands like Mazda have been some of the most successful improving combustion quality of its modern diesel engines (I recommend reading about technology SKYACTIV ). Some small displacement engines have overcome the Euro VI regulation by catalysts which literally trap molecules of NO and NO 2 and absorb as if it were a sponge. A sponge when full must purge or regenerate. Hence, these systems are known as NOx trap , or NOx trap.


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Another solution, which we have already spoken at length, is the type AdBlue systems. Require installation of an additional device, and use of an aqueous urea solution (known commercially as AdBlue), with which it gets drastically reduce the emission of NOx. Obviously, this technique increases the complexity of the engine requires maintenance and requires periodic recharging of the additive. I recommend reading our guide AdBlue to clarify any doubts.

The introduction of these systems was the main motivation for items like “8 Reasons for not buying a diesel, especially for city.” Without going into too much detail on the environmental problem, we try to find economic and technical justifications to remember why diesel is not always (dare I say it almost never is) the most interesting for most drivers alternative.


6. What does the ozone in this?

You’re probably more used to hear conversations about how dangerous is the lack of ozone in the stratosphere. Terrible on the other hand – – “good ozone” and “bad ozone” Hence sole terms used colloquially. But ozone is a pollutant that must worry about much when present in the air you breathe. Tropospheric ozone, the O 3 , is formed in the atmosphere by photochemical reactions in the presence of sunlight and precursor pollutants such as NO x .

The most favorable ozone generation is precisely the environment in cities with high concentrations of NO x , high temperatures and high solar radiation. That is, August in a Spanish capital is perfect for ozone concentrations skyrocket. In fact, ozone is a pollutant that creates more headaches, and environmental and health problems in the summer.


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7. Why is so bad the Volkswagen case?

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it is serious in economic terms. The sanctions that can lead Volkswagen outweigh the benefits obtained before taxes for a year by selling more than 10 million vehicles. It is even more severe in the United States, where deception leads to fatal consequences for any manufacturer and which are experts in claims for damages and class actions.

But above all it is serious for having used a tortuous technique, the defeat device to market vehicles with emissions of NOx far outweigh the actual misleading the consumer and authorities lay siege to the emissions of these gases.

And as we have seen in this article, the NOx are really serious to look away and forget about a compound that problem but not see, we are breathing every day.

Update on the case of diesel Volkswagen
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Volkswagen stopped sales of cars equipped with engine 2.0 TDI US
How they can deceive the approved manufacturers consumption? The Volkswagen case in the United States and Defeat Device
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10 ways to manipulate the homologated consumption (to be so different from actual)
11 million engines 2.0 TDI of the Volkswagen Group have a defeat device that distorts its emissions

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