This document 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 document 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 of the relevant EU air quality directive and the requirements during sampling, calibration and quality assurance. The method is applicable to the determination of the concentration of nitrogen dioxide present in ambient air from 0 µg/m3 to 500 µg/m3 and to the determination of the concentration of nitrogen monoxide present in ambient air from 0 µg/m3 to 1 200 µg/m3. These concentration ranges represent the certification ranges for the type approval test. The method covers the determination of ambient air concentrations of nitrogen dioxide and nitrogen monoxide in zones classified as rural areas, urban-background areas and traffic-orientated locations. When the standard is used for other purposes than for measurements required by EU Directives, the range and uncertainty requirements need not apply.