5. Conclusions

5. CONCLUSIONS AND RECOMMENDATIONS

1. Data for 1996 were received by the European Commission from 14 Member States.

13 Member States provided information on ozone concentrations for a total of 836 monitoring stations. Italy provided information too late to be included fully in this report. From France no information was received.

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

Depending on the local situation, the ozone monitoring stations are characterized as rural, urban, street or other (e.g. industrial). Further work on a harmonized classification system is needed.

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 about 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 65 million people. 12% of this population (7.8 million people) is not exposed to ozone levels exceeding the threshold whereas 6% (3.9 million people) is exposed to exceedances during more than 50 days. The number of days with at least one exceedance observed at the reporting stations within a Member State ranges from 12 (Ireland) to 277 (Spain).

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

The threshold value of 65 µg/m³ (24h-average) is reported to have been 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). Exceedances during more than 150 days are estimated for more than 31% of the area for which the subset of background stations report representative values. The threshold value of 200 µg/m³ (hourly average) is exceeded largely and widely (reported by 10 (out of 13) Member States) on a limited number of days.

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

Exceedance of the information threshold value of 180 µg/m³ (1 h average) was reported for stations in 12 (out of 13) Member States. For two stations an exceedance of the warning level of 360 µg/m³ (1h average) was reported.

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

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

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