PD CEN/TS 18275:2026 PDF

1 Scope This document defines and describes the methodology to calculate Modelling Quality Indicators (MQI) and determine fulfilment of the Modelling Quality Objectives (MQO). MQO are provided to help ensure that modelling-based assessments of air quality in the context of the ambient air quality directive [1] are objective and comparable, and of sufficient quality to obtain reliable information about concentrations of air pollutants in ambient air. The method uses measurement uncertainty and a level of stringency as a benchmark for the acceptable level of difference between modelled and measured values. This document concerns the performance of an entire modelling system therefore the term “modelling quality objectives” is used rather than “model quality objectives”. This document concerns the use of modelling results for assessment as specified in [2]. Such modelling systems aim to capture both the spatial and temporal variability of the environmental indicator under assessment in the modelling domain. This document establishes a method to determine if the results of a modelling system fulfil the MQO and therefore reach an adequate data quality level within the modelling domain defined for assessment. The procedures described in this document are limited in scope as they concern only statistical performance indicators. A full evaluation of a modelling system considers additional elements of quality assurance, but such procedures are outside the scope of this document. This document only addresses modelling applications where measurements of pollutant concentrations are available that meet the d...