2.1 Introduction

According to the ozone directive, the EU Member States have to provide the following information for the annual reference period:

  • maximum, median and 98 percentile value of 1h- and 8h- average concentrations;
  • the number, date and duration of periods during which threshold values as presented in Table 1 are exceeded and the maximum concentrations recorded during each occurrence.

In addition to this annual report, Member States must inform the Commission on a monthly basis if exceedances of the information and warning threshold values are observed.

Table 1. Threshold values for ozone concentrations (in µg/m3)

threshold for concentration averaging period
health protection

vegetation protection

" "

population information

population warning






8 h

1 h

24 h

1 h

1 h

A group of experts from the Members States have followed the practical implementation of the Directive. Among other items this group discussed procedures for data reporting. The formats for information and data exchanges have been defined in the document "Council Directive 92/72/EEC on air pollution by ozone. Information and data exchange/formats", Doc.Rev. 11/243/95. In general terms, the requested information consists of two parts:

  1. information on stations and measurements techniques (Ozone Directive, article 4.2, indents 1 and 2);
    1. information on ozone concentration: annual statistics and threshold exceedances (Ozone Directive, article 6.1).

Based on the experiences in processing the data for the 1994 annual report, the European Topic Centre on Air Quality (ETC-AQ) provided remarks concerning data transmission and suggestions for improvement which were discussed in the Expert Group on Photochemical Pollution. Considering the increasing amount of data requiring processing, as well as the improvement of the transfer of data relating to the implementation of the Directive, the Commission has prepared an update (April 1996) of the data exchange format. The major changes concern the transfer of additional information:

  • type of station: definition of the location of stations as recommended in the decision on Exchanges of Information (97/101/EC);
  • altitude of stations as recommended by the Expert Group;
  • NOx and VOC data, according to Annex 2.3 of the ozone directive;
  • file names: it is recommended to define unique names for all files in order to improve the management and transfer of the data files.

For submission of the 1996 data no further modifications in data requirements and data exchange formats have been made.

2.2 Data handling

According to the Ozone Directive, the requested information over 1996 should have been forwarded to the Commission before 1 July 1997. All data forwarded by the Commission and received at the European Topic Centre on Air Quality (ETC-AQ) before 11 August 1997 has been processed is this report. In this report the definition of the data formats as described in the document Doc.Rev. 11/243/95 and its April 1996 amendment is used as a reference. If necessary, files were converted at the ETC-AQ for further processing.

No information has been received from France. Information from Italy was received more than two months after the formal deadline of 1 July. The received data were, however, not fully in agreement with the standard data format which impeded data analyses. As time and resources were limited, the Italian data has not been included fully in this report. However, as far as possible the Italian data are included in the overview Tables 2-6 and a preliminary survey of exceedances in Italy is presented in Chapter 4.6.

For 1996 information on ozone concentrations (annual statistics and/or exceedance information) was received for 836 monitoring stations. For nearly all stations information was submitted on measurement methods, instruments and calibration procedures. In comparison to 1995, information for a slightly smaller number of stations was received (see Figure 1). Comparison of 1995 and 1996 is hampered by the fact that information from two Member States is missing. If one assumes that in those countries the same number of stations is operational in 1995 and 1996, there is an increase in information, see the bar labelled 96-B in Figure 1.

Information on NOx concentrations has been received from 6 Member States (90 stations); 8 Member States reported on NO2 concentrations (122 stations). Information on Volatile Organic Compounds (VOC) was reported by two Member States at five stations.

Figure 1. Number of stations reporting ozone data within the framework of the Ozone Directive. The bar "96" refers to the actual 13 reporting Member States; in "96-B" a correction has been made for missing data.

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