Low emission zones reduce PM₁₀ mass concentrations and diesel soot in German cities

Abstract

In many European cities mass concentrations of PM₁₀ (particles less than 10 μm in size) are still exceeding air quality standards as set by the European Commission in 1999. As a consequence, many cities introduced low emission zones (LEZs) to improve air quality and to meet the limit values. In Germany currently 48 LEZs are in operation. By means of dispersion modeling, PM₁₀ concentrations were estimated to decrease up to 10%. Analysis of PM₁₀ levels conducted for Cologne, Berlin, and Munich some time after the LEZs were introduced showed reduction of PM₁₀ mass concentration in the estimated range. The PM₁₀ particle fraction is, however, composed of particles with varying toxicity, of which diesel soot is highly health relevant. An evaluation of air quality data conducted in Berlin showed that in 2010 traffic-related soot concentrations measured along major roads decreased by 52% compared to 2007. Diesel particle emissions in Berlin were reduced in 2012 by 63% compared to a business-as-usual scenario (reference year 2007). A strong reduction of the traffic-related particle fraction of PM_2.5 was also reported for Munich. Therefore, it is likely that the effects of LEZs are considerably more significant to human health than was anticipated when only considering the reduction of PM₁₀ mass concentrations.

Implications: 

The implementation of low emission zones in German cities might result in a reduction of PM₁₀ levels concentrations by up to 10%. However, it is difficult to show a reduction of PM₁₀ annual averages in this order of magnitude as meteorology has a large impact on the year-to-year variation of PM mass concentrations. Monitoring of other PM metrics such as black smoke (BS) or elemental carbon (EC) might be a better strategy for evaluating LEZs effects. The benefit of low emission zones on human health is far greater than is presently visible from routine measurements of PM₁₀.

Acknowledgments

The authors thank Hanna Kirchmair for the translation of the German text draft.

Additional information

Notes on contributors

Josef Cyrys

Josef Cyrys is senior scientist working on exposure assessment related topics at the Helmholtz Zentrum München in Neuherberg, Germany and the Environmental Science Center at Augsburg University, Germany.

Annette Peters

Annette Peters is director of the Institute of Epidemiology II at Helmholtz Zentrum München in Neuherberg, Germany and adjunct professor at the Harvard School of Public Health in Boston, USA.

Jens Soentgen

Jens Soentgen is scientific director at the Environmental Science Center at Augsburg University, Germany

H.-Erich Wichmann

H.-Erich Wichmann is former Director of the Institute of Epidemiology at Helmholtz Zentrum München and Professor emeritus for Epidemiology at the Ludwig Maximilians University München.