1. Introduction

1. INTRODUCTION

In view of the harmful effects of photochemical pollution in the lower levels of the atmosphere, the Council adopted in 1992 the Directive 92/72/EEC on air pollution by ozone. The Directive came into force on 21st March 1994. It established procedures for harmonized monitoring of ozone concentrations, exchanging of information, communicating and alerting the population regarding ozone and to optimize the action needed to reduce ozone formation.

Article 6 of the Directive specifies how the information on monitoring results must be provided by the Member States to the Commission. Regarding the time frame, two main types of reporting can be distinguished. Information on exceedances of the so-called information threshold (article 6 sub 2) and warning threshold (article 6 sub 3) for the ozone concentration is to be provided shortly after occurrence. Information on the results for a complete calendar year must be provided within six months following the annual reference period (article 6 sub 1). Article 7 of the Directive stipulates that the Commission shall at least once a year evaluate the data collected under the Directive. The present report is the second report of the EEA on annual data that have been received by the Commission; it gives an overview of ozone monitoring results of 1995. An overview of the 1994 annual data has been prepared by the European Topic Centre on Air Quality (de Leeuw et al., 1995; van Zantvoort and Sluyter, 1996).

Following article 7 of the Directive, the Expert Group on Photochemical Pollution was established by the Commission. This group convenes several times per year to coordinate the work within the Member States and the Commission in the framework of the Directive.

The data reported here does not cover all ozone monitoring stations in the European Union. For inclusion in this report, the data must satisfy certain criteria stipulated in the Directive, concerning inter alia measuring methods, sampling methods, station siting, quality assurance and documentation. Formats on the transfer of data have been defined by the Expert Group.

Prior to the current report an overview on ozone threshold exceedances during Summer 1995 (May-July) has been presented at the Council meeting of October 1995 (EC, 1995). Background information on the current experience and knowledge concerning the problem of photochemical air pollution, dealing in particular with the phenomenology of ozone, the scientific understanding, as based on experiments and theory, and the insights from modeling studies on the relation between ozone levels and precursor emissions may be found in Borrell and Van den Hout (1995) and Derwent and Van den Hout (1995) and Barrett and Berge (1996).