This European Standard specifies a continuous measurement method for the determination of the concentrations of nitrogen dioxide and nitrogen monoxide present in ambient air based on the chemiluminescence measuring principle. This standard describes the performance characteristics and sets the relevant minimum criteria required to select an appropriate chemiluminescence 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 as specified in Annex I of Directive 2008/50/EC  and requirements during sampling, calibration and quality assurance for use. The method is applicable to the determination of the concentration of nitrogen dioxide present in ambient air up to 500 μg/m3. This concentration range represents the certification range for NO2 for the type approval test. The method is applicable to the determination of the concentration of nitrogen monoxide present in ambient air up to 1 200 μg/m3. This concentration range represents the certification range for NO for the type approval test.