US EPA

5935146 

Journal Article 

Umweltzonen 

Cyrys, J; Peters, A; Soentgen, J; Gu, J; Wichmann, HE 

2015 

Chk 

Umweltmedizin in Forschung und Praxis
ISSN: 1430-8681 

Ecomed Publishers 

20 

1 

33-57 

English; German 

Low Emission Zones (LEZs) were implemented as a measure for improving air quality of ambient air, especially in cities where the European limit values for PM<inf>10</inf> (particulate matter with an aerodynamic diameter < 10 µm) were exceeded. Up to now 48 LEZs were introduced in Germany (by the end of 2014); however they differ significantly from city to city regarding size, implementation time and strictness of regulation. In general, the vehicles are identified by windscreen badges in a coloured code which is directly linked to the corresponding stages of European emission standards. In other European countries LEZs (or other measures such as Congestion Charge Zones) have been also implemented; however, there are no uniform regulations for LEZs in the different EU member states. The effects of LEZs on the air quality have already been investigated by dispersion modeling or increasingly also by analysis of PM<inf>10</inf> measurement values. While initially inconsistent results were reported due to short time series of PM<inf>10</inf> measurements, recent studies show a clear trend. In sufficiently large and strictly regulated LEZs a reduction of PM<inf>10</inf> concentration between 5 and 10[%] (at traffic site partially above 10[%]) can be expected. The reduction of PM<inf>10</inf> levels is in general more pronounced for the summer season compared to the winter season. In winter, additional particle sources (such as domestic heating, wood combustion, re-suspended dust due to the application of road salt for deicing) contribute significantly to the PM<inf>10</inf> mass concentrations and consequently a measure regulating vehicle exhaust particles only becomes less effective. It has been shown that air pollutants which are emitted mainly by traffic and especially by diesel cars (elemental carbon (EC), diesel soot, ultrafine particles, PM<inf>2.5</inf>) are more affected by the implementation of LEZs. After the implementation of LEZ in Munich the average concentration of EC emitted by traffic decreased by 50[%]. In Berlin the diesel particle emissions were reduced by 63[%] compared to a business-as-usual scenario. The limit values for PM<inf>10</inf> were introduced in 2005 mainly due to the adverse health effects of fine particles on respiratory and cardiovascular morbidity and mortality. The most health-relevant PM<inf>10</inf> particle fraction consists mainly of traffic related particles and here especially of diesel soot particles. Therefore, the German regulations for LEZs promote using of diesel particulate filter (DPF) in diesel cars. Unfortunately, the evaluation of the LEZ effects is mostly restricted to PM<inf>10</inf>, a particle fraction containing on average only 20[%] of exhaust related particles. A 10[%] reduction of PM<inf>10</inf> should lead to a reduction of the toxic and health-relevant diesel soot fraction by 50[%], which was already reported for some "efficient" LEZs. This means at the same time that the benefit of LEZs on human health is far greater than is presently visible from routine measurements of PM<inf>10</inf>. Overall, the results show that LEZs are proving successful as a measure for air pollution control when they are large enough and only few exemptions are granted. They decrease not only PM<inf>10</inf> but, to a much higher degree, the health-relevant components (such as diesel soot) contained in PM<inf>10</inf>. Therefore, the benefit of the LEZs could be much better estimated by additional monitoring of diesel soot and elemental carbon in PM<inf>10</inf>.