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“Nitrogen Oxide and Particulate Matter Are the Major Problems We Face Today”

40 years after Germany’s first smog alert: An interview with atmospheric researcher Astrid Kiendler-Scharr

Jülich, 16 January 2019 – Forty years ago, on 17 January 1979, the first-ever smog alert was issued in Germany. Air pollution in the Ruhr region had reached extraordinarily high levels: in Duisburg, 1,400 micrograms (µg) of sulfur dioxide per cubic metre of air had been recorded, whereas the limit value at the time was 800 µg. Since then, air quality has improved considerably. In the following interview, Prof. Astrid Kiendler-Scharr, director at Forschungszentrum Jülich’s Troposphere subinstitute, outlines the measures that contributed to this improvement and the way in which traffic emissions pollute the air today.

Prof. Astrid Kiendler-ScharrProf. Astrid Kiendler-Scharr
Copyright: Sascha Kreklau

What were the reasons behind the first smog alert?

Prof. Kiendler-Scharr: The smog alert issued 40 years ago was of the “London smog” type, named after the serious smog event that took place in London in the winter of 1952. The smog was caused by a combination of emissions – particularly sulfur dioxide from power plants, domestic heating, and industry – and inversion, a weather condition in which low air exchange leads to a high concentration of pollutants.

Which measures proved helpful at the time?

Prof. Kiendler-Scharr: The systematic purification of exhaust gases in particular, as well as the desulfurization of fuels like petrol and diesel, have led to sulfur dioxide no longer being a cause of air quality problems here in Germany.

Are smog alerts a thing of the past? What kind of problems are we facing today?

Prof. Kiendler-Scharr: Although smog alerts – both in winter and summer – have indeed become a thing of the past here, limit values for air quality continue to be exceeded. Nitrogen oxide and particulate matter are the major problems we face today. The World Health Organization (WHO) classifies particulate-matter pollution as one of the largest environmental health risks in existence.

Where in Germany are the biggest problems being faced, and why?

Prof. Kiendler-Scharr: Traffic is a major source of both nitrogen oxide and particulate matter. In areas close to traffic, the limit values are often exceeded. In the past and in other parts of the world, high levels of emissions coinciding with certain meteorological conditions have often triggered particularly heavy pollution. Valley areas such as Stuttgart are frequently affected by this problem.

From a scientific perspective, what needs to happen in order to combat these problems? Are vehicle bans the solution?

Prof. Kiendler-Scharr: To reduce pollution from nitrogen oxide, a holistic view must be taken of the transport and traffic sector. Our road transport measurements suggest that passenger car traffic is not the main cause of nitrogen oxide pollution. If public transport and delivery services were to switch to alternative drive technologies – i.e. e-mobility – this could have a significant impact.

Further information:

Research on urban air quality

Research with the MobiLab mobile lab

Press release on nitrogen oxide in Düsseldorf (in German): “Stickoxide in Düsseldorf: Neue Daten zeigen, wie die Schadstoffe verteilt sind” (2 May 2018)

Interview with Dr. Franz Rohrer on the diesel debate (in German): “Mit Nachrüstungen und Umtauschaktionen für Pkw allein lassen sich die Grenzwerte in Städten kaum einhalten” (27 September 2018)


Prof. Astrid Kiendler-Scharr
Tel.: +49 2461 61-4185

Press Contact:

Erhard Zeiss, Pressereferent
Tel.: +49 2461 61-1841