Berlin Environmental Atlas

03.06 Near Ground Ozone (Edition 1993)

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Map 03.06.3: Infringement of Standard Values 1992

In this map the average spatial distribution of the ozone concentration in Berlin is shown. The days were selected on which individual stations of the Berlin Air Quality Monitoring Network recorded measurements in excess of threshold values. The choice of the threshold values was the "maximum pollution concentration" (MIK) according to VDI 2310 with 120 µg/m³ as half-hourly average and the threshold value of the EC Guideline on the notification of the population with 180 µg/m³ per hour average (cf. Tab. 1).

To make clear the dependence of the ozone burden on the local nitrogen oxide emission, the frequency with which the values were exceeded was collated with the distribution of nitrogen oxide emission from traffic. In the comparison of both statements it becomes clear that high nitrogen oxide emissions lead to clearly fewer infringements of the ozone threshold values in the vicinity of a measuring point. So the MIK is overstepped at the city expressway value four times more rarely than at the stations on the outskirts of town, where in the summer the value of 120 µg/m³ an was overstepped on more than 100 days. The values at the remaining measuring points, not lying directly on main thoroughfares in the inner city lie at 70 to 80 infringements between them. The station Mitte lies clearly under it with 57 days. However, due to the central situation western which run past busy streets has reacted and because of a part of the ozone with the nitrogen oxides. The photochemical formation mechanisms, for the most part, cannot compensate for this decomposition because the ozone forming are processes described above are complex and take time during which the air has already moved to a large extent from the city to the outside areas and the surrounding countryside. The Berlin forests lie however as a rule in these areas and therefore in the influence area. Thus for the year 1992 limits to the protection of the vegetation and several indicators listed in Table 1 were overstepped at the forest measuring point Grunewald. For instance the daily median value from the EC Guideline of 65 µg/m³ was overstepped on 141 days and the WHO value of 60 µg/m³ for the entire vegetation time was clearly exceeded, with 81 µg/m³ actually measured.

A similar picture emerges for the infringement of the EC threshold values, for which behavioral recommendations for sensitive persons are published by the Berlin Department of Urban Development and Environmental Protection. On the outskirts of town this occurred from 19 to 23 days in 1992. In the inner city residential areas this happened from 11 to 17 days, in Mitte only six times and at the city expressway not at all. The respective infringement numbers at the measuring points are in first approximation transferable to other urban areas with more comparable nitrogen oxide emissions.

The infringement frequencies at the tower measuring point in Frohnau are very much higher. It could already be seen from Map 03.06.2 that there ozone decomposing effects hardly play a role and therefore high concentrations are more frequently measured. Also at the measuring point Grunewald the infringement frequencies of the MIK value in the sampling at 10 m elevation above the trees are somewhat higher than in 4 m amount in the forest, where ozone can be decomposed at the plant parts. So that is joined however at the same time a plant damaging effect, which presents additionally an essential part for the impairment of the entire forest ecosystem (see results of Long-Term Ecological Monitoring Program for Forest Ecosystems, cf. SenStadtUm 1993).

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