5. Conclusions and recommendations

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5. Conclusions and Recommendations

1. Data for 1995 have been received by the European Commission from 15 Member States for 858 monitoring stations.

The quality and quantity of the information supplied by the Member States for 1995 is strongly improved compared to 1994. The improved formats for reporting have resulted in a good harmonization of the data reports although in some cases deviations from the formats occurred. Suggestions for further improvement of data transmission are presented in Annex III.

2. The spatial coverage and quality documentation of the data need improvement.

Depending on the local situation, the ozone monitoring stations are characterized as rural, urban, street or other (e.g. industrial).

The present subset of rural stations is not representative for the land area of the EU: the subset is estimated to cover only 40-50%. The subset of urban stations is insufficient to estimate the exposure of the population living in all cities with more than 25 000 inhabitants: the urban subset covers at most 30% of the urban population.

Spatial coverage and documentation of the monitoring data quality need improvement if the level of protection of human health and ecosystems in Europe to elevated ozone levels is to be fully assessed. Member States are encouraged to reconsider their ozone measuring networks in the light of the spatial coverage of ozone monitoring stations. It is recommended to improve the documentation on the representativity and on the surrounding of the existing stations.

3. The threshold value set for the protection of human health was exceeded substantially in all Member States.

The threshold value of 110 µg/m3 (8h-average) was exceeded substantially (in c. 25% of the reported exceedances the 8h-average concentrations exceeded 165 µg/m3). The subset of urban stations is assumed to give representative values for the exposure of an urban population of approximately 58 million people. 18% of this population is not exposed to ozone levels exceeding the threshold whereas 9% is exposed to exceedances during more than 50 days. The number of exceedances averaged over all stations in each Member State varies from 5 to 54 with an average of 28 for the EU-15.

4. The threshold values set for the protection of vegetation were exceeded substantially and in almost all the EU Member States.

The threshold value of 65 µg/m3 (24h-average) is reported to be exceeded substantially (by up to a factor 3), widely (in all reporting Member States) and frequently (several Member States report exceedances during more than 150 days at some of their stations). In less than 1% of the area for which the subset of background stations report representative values, this threshold value is not exceeded; exceedances during more than 150 days are estimated for more than 27% of the area. The threshold value of 200 µg/m3 (hourly average) is exceeded largely and widely (reported by 14 Member States) on a limited number of days.

5. The threshold value for information of the population was exceeded in almost all the EU Member States during a limited number of days.

Exceedance of the information threshold value of 180 µg/m3 (1 h average) has been reported for stations in 14 Member States. For one station an exceedance of the warning level of 360 µg/m3 (1h average) has been reported.

6. It is recommended to improve the reporting of ozone precursors (NOx, NO2 and VOC).

NOx measurements should be co-located with the ozone monitoring stations as NOx can be used as an indicator of the station representativity. Moreover, precursor concentrations will be needed for testing of compliance with VOC and NOx emission reduction programs.


European Environment Agency (EEA)
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