4.5. Comparison with 1994

4.5 Comparison with 1994

In comparison with 1994 the quality and quantity of the information submitted by the Member States in the framework of the Ozone Directive has been substantially improved. The data is nearly complete (see Table 2). Suggestions to further improve the data transmission are made in Annex III.

With respect to the ozone exceedances no clear differences between the years can be seen. Partly this is caused by the fact that the information for 1994 was incomplete, partly by the changes in or extension of the national ozone monitoring networks. Most Member States reported a small increase in the occurrence of exceedances for the vegetation related threshold value of 65 µg/m3, however, in Finland, Ireland and Portugal a very strong increase is found. To a large extent this will be caused by the increase in the number of stations reported.

The occurrence of exceedances of the 110 µg/m3 level for 8-hourly averaged concentrations increased slightly in most countries. Notable exceptions are found for Austria, Germany, Denmark, and Finland. The change in occurrence of exceedances of the hourly threshold values of 180 and 200 µg/m3 varies from country to country: in six MS an increase, in five MS a decrease in the number of exceedances of 200 µg/m3 is found whereas in two MS this number remains constant. For the 180 µg/m3 level a similar result is obtained: increases in occurrence of exceedances in five MS, decreases in seven MS and constant in one MS.

Examination of the results per Member State showed that only in Austria the number of exceedances of all threshold values decreases. In Germany a decrease is observed for 1h and 8h values but for the 24h value an increase is observed. An increase in the number of exceedances for all threshold values is found in Belgium and Luxembourg, the United Kingdom and Ireland. For Ireland the increase might result from the extension of the monitoring network. For the other Member States both upward and downward fluctuations are found.