2 AVAILABILITY OF DATA

2 AVAILABILITY OF DATA

According to the Directive, exceedances of the population information and warning thresholds are to be transmitted to the Commission within one month following the observation. On basis of the experience gained with the ozone data reporting in 1995, the Commission updated the formats to be used and gave additional guidelines to ensure successful transmission of data [5]. In this report, the definition of data formats as described in the above mentioned guideline document is used as reference. If necessary, files were converted at the European Topic Centre on Air Quality (ETC-AQ) for further processing. In this report all data received by The Commission (DGXI) and forwarded to the ETC-AQ not later then 15 September 1996 have been included in the analysis.

For all 15 EU Member States, information concerning the observation of exceedances during the months April-July 1996 is available. Only for Spain, no information for July has been received in time for this report. Table 2 presents an overview of observed exceedances per country per month.

Table 2: Overview of observed exceedances per month per country. yes: exceedance of the population information threshold reported, no: no exceedance reported, ?: no reporting received.

Member States were requested to check the information made available to the Commission on ozone monitoring sites implemented in the framework of the Directive. For the interpretation of ozone data it is essential to have information on the direct surroundings of the station since the ozone concentration may be scavenged by locally emitted nitrogen oxides or by enhanced dry deposition which might occur for exmaple under a forest canopy. Member States were requested to classify their stations as street, urban background or rural stations as a first description of the environment of the stations. Map 1 presents the location of all ozone monitoring stations (street and urban background taken together as 'urban') which were scheduled to be operational during the 1996 summer season, based on the information supplied by the Member States. 1012 ozone monitoring sites are operational in the framework of the Directive. This amounts to an increase of 154 stations since 1995. From the 1012 ozone monitoring stations, 272 stations are situated in rural areas, 283 stations in urban background environments, 163 are street stations and for 294 stations the monitoring environment was not specified.

Note that due to the fact that since only exceedances of thresholds were reported, it is not clear that stations were operational continuously. It is possible that ozone concentrations exceeded a threshold at a site but was not reported because the monitoring station was temporarily out of operation.

In this report exceedances are counted on a daily basis, that is, a day on which a threshold is exceeded at least once, is calculated as one exceedance day. Note that information presented in this document is not necessarily based on validated monitoring data and hence should be considered preliminary.

Map 1: Ozone monitoring stations implemented in the framework of Directive 92/72/EEC on air pollution by ozone, scheduled to be operational during 1996.