Nitric oxide calculator reveals reduction needs

Online tool shows correlation of local NO2 levels with traffic emissions

A new online calculator shows local nitrogen oxide levels and the necessary reductions in traffic emissions © Forschungszentrum Jülich
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More insight in the value jungle: With an online tool, you can now look up how high the nitrogen oxide emissions are at your place of residence - for each measuring point. The trick here: The nitrogen oxide calculator also reveals how much the traffic emissions at this location would have to be lowered in order to comply with the limit value. Because vehicles emit various nitrogen oxides, this is less trivial than you think.

The facts seem clear: In many German cities, the nitrogen oxide levels of the air are too high. Although some physicians have recently denied that nitrogen dioxide (NO2) is harmful to health, the majority of studies say otherwise. Thus, inhalation experiments show that NO2 causes inflammatory processes and irritation in the lungs, as well as increases the risk of asthma attacks and cardiovascular diseases.

But how high is the burden in my neighborhood? And how much nitrogen oxide emissions should be avoided here?

Online calculator shows load at each measuring point

Scientists at Forschungszentrum Jülich have now introduced a nitric oxide calculator, with which you can easily find out the nitrogen oxide load at each German measuring point over time. In the online tool you select city and measurement point and then get a graph that shows the concentration of nitrogen dioxide (NO2) of the last annual mean and the exceedances of the limit.

"The tool makes it easy to see how annual mean values ​​have changed over time and whether previous reduction measures have been successful, " explains Martin Schultz from the Jülich Supercomputing Center. Data basis are the official measurements of the Federal Environmental Agency. display

Nitric oxide is not the same as nitrogen dioxide

The special feature, however, is that the computer also determines how much the local nitrogen oxide emissions from traffic have to be reduced to ensure that the legal limit is met. "In the public discussion, practically only the measured NO2 values ​​are mentioned. This gives rise to completely misconceptions about how much one would actually have to reduce emissions in traffic, "says Franz Rohrer from Forschungszentrum J lich.

From NO and NO2 values, the tool calculates the necessary emission reductions during transport. Research Center J lich

The problem: The relationship between nitrogen oxide emissions and measured values ​​is not trivial. How much the nitrogen oxide emissions have to be reduced can not be deduced directly from the exceedance of the NO2 limit value. Exhaust gases contain different types of nitrogen oxides (NOx). Only a small proportion, about 15 percent, is harmful nitric dioxide (NO2), to which the legal limit refers. By contrast, most of the nitrogen oxides (NOx) are emitted in the form of nitrogen monoxide (NO), for which there is no comparable limit value.

The more nitrogen oxides, the slower the NO2 drops

Nevertheless, nitrogen monoxide (NO) also partially contributes to the increase in NO2 levels. After all, parts of the NO are subsequently converted into nitrogen dioxide (NO2) in a reaction with ozone. However, the conversion of NO to NO2 does not take place completely and not always in equal parts. The more nitrogen monoxide (NO) in the air, the lower the percentage that is converted to nitrogen dioxide (NO2).

However, this means that if you want to lower a high concentration of NO2 in the air, you will need to make relatively small cuts in traffic-related emissions. This is because first of all the NO content in the air is lowered, the NO2 values ​​decrease more slowly than at low values. In terms of percentage, emissions must therefore be reduced by a significantly higher proportion than seems due to the limit value exceedance alone.

"Measuring 50 milligrams per cubic meter, as opposed to 40 milligrams, does not mean emissions have to go down by 20 percent. In fact, it's more like 40 percent, "explains Rohrer. Any reduction needed at which location, everyone can now even look in the online calculator.

To the nitrogen oxide calculator of the J licher researchers

Source: Forschungszentrum J lich

- Nadja Podbregar