2. Data Reporting

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 ozone 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 in case exceedances of the information and warning threshold values are observed. In this report only data reported on an annual basis will be considered.

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

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);
2. 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;
• NO_x 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 1997 data no further modifications in data requirements and data exchange formats have been made. Non-EU countries have been requested to submit their data in agreement with these data exchange formats.

2.2 Data handling

According to the Ozone Directive the requested information over 1997 should have been forwarded to the Commission before 1 July 1998. All data forwarded by the Commission and received at the European Topic Centre on Air Quality (ETC-AQ) before 12 August 1998 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.

Non-EU Member States were contacted via the European Environment Agency, via the Phare Topic Link on Air Quality or, in case of Switzerland, directly and asked to voluntary submit data following the standard formats on data exchange. Information has been received from Switzerland, the Czech Republic, Latvia, Norway and Poland. At a very late moment (18 September 1998) data from 8 stations in Slovakia has been received. Although the data was delivered according to the agreed formats, the limited time and resources did not allow to fully include the data in this report. Data from Slovakia are included only in the overview tables 2-5 presented in Chapter 2 and 3.

The summary of received information presented in Table 2 shows that the information for the EU is nearly complete. However, analysing the data revealed a number of errors, ambiguities or missing data. It was attempted to contact national data suppliers to clarify these points but generally this was not successful. Lack of e-mail addresses or fax-numbers hampered a rapid dialogue.

Spain has not submitted statistical information and an incomplete set of exceedances.

The data received from Italy was of a low quality. Typical errors frequently found in the Italian information are:

• incomplete set of station information (co-ordinates, unique coding, station type, etc. is missing);
• incomplete date of exceedance (month but not day or hour is given);
• inconsistent information on exceedances of the 180 µg/m³ and 200 µg/m³ threshold: for a number of stations, exceedances of the 200 µg/m³ threshold are not quoted as exceedance of the 180 µg/m³ threshold;
• there are clear indications that for a number of stations, in case of exceedance of the daily threshold value of 65 µg/m³ the quoted maximum concentration refers to an hourly averaged concentration in stead of the daily mean.

The data from France contain inconsistent information on exceedances of the 180 µg/m³ and 200 µg/m³ threshold: for a number of stations, exceedances of the 200 µg/m³ threshold are not quoted as exceedance of the 180 µg/m³ threshold.

The statistical information of the Netherlands was in an incorrect format; information on data coverage was not given. This precluded the further use of the Dutch statistical information in the analysis.

A Measurement techniques file was not received for a number of countries. Voluntary data on precursor concentrations has been received for nine Member States and two additional countries.

For 1997 information on ozone concentrations (annual statistics and/or exceedance information) has been received for 1076 monitoring stations of which 984 were located in EU-Member States. Figure 1 indicates that the number of reporting stations is still growing. The large increase compared to 1996 is mainly due to the fact that over 1996 only 13 Member States submitted information.

Figure 1. Number of stations reporting ozone data within the framework of the ozone directive. Note that 1996 refers to the actual reporting Member States. For stations in non-EU countries a station classification is known but not resolved in this figure to maintain consistency with earlier years for EU Member States.

Table 2. Summary of received information over 1997.

x: delivered;
-: not delivered;
(1) wrong format;
(2) originally data in wrong format; updated file received 18 August 1998;
(3) only period March-October; only exceedances of 180 µg/m³ (1h-averaged);
(4) no 1997-update received; information submitted for 1996 has been used;
(5) hourly data submitted for period April-December 1997; exceedances and statistics calculated by ETC/AQ;
(6) Information on NO₂ and NO (not NO_x) has been received.