Wirksamkeit von Umweltzonen in der ersten Stufe: Analyse der Feinstaubkonzentrationsänderungen (PM10) in 19 deutschen Städten

Abstract

It is not known/is disputed whether introduction of low emission zones (LEZs) leads to a reduction of fine dust pollutants. Data on PM10 concentrations obtained from measurement stations within and outside of LEZs from 19 German cities (Augsburg, Berlin, Dortmund, Duisburg, Düsseldorf, Essen, Frankfurt a. M., Hannover, Herrenberg, Ilsfeld, Karlsruhe, Köln, Ludwigsburg, Mannheim, München, Reutlingen, Stuttgart, Tübingen, Wuppertal) were analyzed in order to investigate the effect of banning vehicles ("tier 1") of the pollutant group 1 (without stickers) on the pollutant concentration, i.e, this study focused on LEZs that restricted cars of EURO 1 standard without appropriate retrofitting systems from entering these zones. For the period from about 2005 until the end of 2009, data from continuous half-hour measurements as well as gravimetrically determined daily measurements of PM10 were collected. The analysis consisted of four pairwise corresponding measurement values as matched quadruples of two index and two reference values (index stations are inside, and reference stations are outside the LEZs). One index value and the simultaneous reference value were measured during the active LEZ period, and the other pair of values was measured before the LEZ was introduced. The pairs of values had a difference in time of 364 days or a multiple of 364 days keeping the season, weekday and time of day constant within the quadruple. Differences in index values were regressed on differences in reference values while meteorological parameters (height of the inversion base, amount of precipitation, wind velocity), school holidays, period of environmental bonus paid, periods when trucks were banned as well as baseline data at index and reference stations were taken into account as covariates in so-called "fixed effects" regression analyses of the quadruples (difference score method in the two-period case). The statistical approach was successfully validated prior to this study in an analysis of simulated data from FU Berlin. 2,110,803 quadruples of continuous PM10 and 15,735 gravimetric quadruples were identified leading to 61,169 quadruples based on daily PM10 averages. The analyses showed that best LEZ effect estimates for fine dust reduction were (at all index stations) ≤ 0.2 μg/m3, i. e., a relative PM10 reduction ≤ 1 %. Best estimates at all index stations near traffic (excluding urban background and industry index stations) were below 1 μg/m3 (less than 5 %, respectively). Effects were smaller than predicted prior to the introduction of LEZs. This study is the first that investigated comprehensively the effectiveness of "tier 1" LEZs in Germany on PM10 reduction with a homogeneous approach in data collection and analysis and taking into account the most relevant confounding factors.