Particulate matter – does it matter?

There has been a lot of talk about particulate matter and threshold limits. And as the debate surrounding diesel bans, particulates, and nitrogen oxides has become so heated, it’s time for an objective look at the facts. We spoke to DEKRA emissions expert Jürgen Bachmann.

The topics particulate matter, nitrogen oxides and thresholds​​are are much discussed. Photo: Fotolia – bluedesign

DEKRA solutions: Mr. Bachmann, did the debate at the start of the year take us any further forward?

Jürgen Bachmann: Absolutely not. In fact, it verged on the absurd. The campaign mounted by a group of retired pulmonologists, led by Dieter Köhler, simply created more uncertainty. The scientific basis was dubious from the start – and the fact that the group themselves identified serious calculation errors in their work was the icing on the cake.

But just to be clear: are the thresholds right?

It’s not a question of right or wrong. Thresholds are a matter of fact. Consider the process on which they are based. It starts with environmental scientists at renowned research institutions who meticulously prepare epidemiological studies on the links between disease patterns and air pollution. These studies are used as a basis for the recommendations issued by the World Health Organization. These are the guideline values. What follows next is an act of political policy formulation. As with every political action, this is a compromise between what is ­necessary and what can be reasonably accepted. The EU Commission has decided on the now famous threshold of 40 micrograms per cubic meter, which is binding for all EU countries. As such, it is irrefutably valid. Furthermore, it is set at a level that also protects people with preexisting medical conditions, as well as older/weaker individuals and children under constant exposure to air pollution.

Another accusation is that air quality is being measured in the wrong places. Is this true?

Annex 3 to the 39th German Federal Solvent Ordinance sets out where measuring points are to be placed. And the operators of state measurement networks adhere to these guidelines. To be on the safe side, however, the German Federal Environment Agency is currently conducting a third-party review of measuring points where values have been recorded in excess of the thresholds.

So the debate, as conducted in the past few weeks, is not very useful?

It is useful in the sense that it has raised public awareness of the issue. The manner in which it was conducted was unnecessary and only led to more confusion. Studies such as the latest ICCT study on the death rate due to transport-related air pollution (published in late February) cannot simply be invalidated by saying that you have never seen any people who died from nitrogen oxide. Facts are what count.

Jürgen Bachmann is an emissions expert at DEKRA. Photo: DEKRA

Jürgen Bachmann is an emissions expert at DEKRA. Photo: DEKRA

But is the data used by the International Council on Clean Transportation (ICCT), an environmentally focused research institute, reliable?

Researchers from the George Washington University and the University of Colorado Boulder were involved in the study. So why should I doubt its findings? The ICCT study is certainly very clear. It finds that 3.4 million people worldwide die prematurely from the effects of air pollution, i.e. particulate matter, nitrogen dioxide, and ozone. With approx. 13,000 fatalities, Germany has the fourth highest death rate. Only three countries – China, India, and the United States – witness more premature deaths caused by low air quality.

What conclusions should we draw from this?

Particularly as we are a high-tech country, we cannot relax our efforts to further minimize the level of harmful substances across the board, whether in terms of transport, the phasing out of brown coal, or the future of renewable energies. And this applies globally. It’s up to us to respect the rights of future generations.

Particulate matter

Microscopic particles suspended in the air. They are divided into different size categories: PM10 (particles that are smaller than 10 micrometers), PM2.5 (particles that are smaller than 2.5 micrometers), and ultrafine particles (smaller than 0.1 micrometers). The smaller the particles, the more dangerous they are. According to the German Federal Environment Agency, road traffic is the main source of particulate matter in built-up areas. It is caused not only by the combustion process in engines, but also the abrasion of brakes and tires as well as the swirling up of particles already on the roads.

Nitrogen oxides

Gaseous compounds of nitrogen (N) and oxygen (O). As there are so many different varieties, they are referred to collectively as “NOx.” In relation to vehicle emissions, NOx usually refers to the total of emitted nitrogen monoxide (NO) and nitrogen dioxide (NO2). Nitrogen oxides account for the third-largest share of vehicle emissions, after carbon dioxide and carbon monoxide. Diesel cars are the biggest emitters of nitrogen oxides in the transport sector. According to the German Federal Environment Agency, they are responsible for more than 73 percent of emissions in urban areas.

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