This European Standard specifies a continuous measurement method for the determination of the concentrations of ozone present in ambient air based on the ultraviolet photometric measuring principle. This standard describes the performance characteristics and sets the relevant minimum criteria required to select an appropriate ultraviolet photometric analyser by means of type approval tests. It also includes the evaluation of the suitability of an analyser for use in a specific fixed site so as to meet the data quality requirements of Annex I of Directive 2008/50/EC and requirements during sampling, calibration and quality assurance. The method is applicable to the determination of the concentration of ozone present in ambient air up to 500 µg/m 3 . This concentration range represents the certification range for ozone for the type approval test. NOTE 1 Other ranges may be used for measurement systems applied at rural locations monitoring ecosystems. NOTE 2 When the standard is used for other purposes than Directive 2008/50/EC, the range and uncertainty requirements may not apply. The method covers the determination of ambient air concentrations of ozone in zones classified as rural areas, urban and urban-background areas. The results are expressed in µg/m 3 (at 20 °C and 101,3 kPa). NOTE 3500 µg/m 3 of O3 corresponds to 250 nmol/mol of O3 at 20 °C and 101,3 kPa. This standard contains information for different groups of users. Clauses 5 to 7 and Annexes B and C contain general information about the principles of ozone measurement by ultraviolet photometric analyser and sampling equipment. Clause 8 and Annex E are specifically directed towards test houses and laboratories that perform type-approval testing of ozone analysers. These sections contain information about: Type-approval test conditions, test procedures and test requirements; Analyser performance requirements; Evaluation of the type-approval test results; Evaluation of the uncertainty of the measurement results of the ozone analyser based on the type-approval test results. Clauses 9 to 11 and Annexes F and G are directed towards monitoring networks performing the practical measurements of ozone in ambient air. These sections contain information about: Initial installation of the analyser in the monitoring network and acceptance testing; Ongoing quality assurance/quality control; Calculation and reporting of measurement results; Evaluation of the uncertainty of measurement results under practical monitoring conditions.