With regard to air quality, interlaboratory comparisons are carried out in compliance with Article 17 of Legislative Decree No. 155 of 13 August 2010, implementing Directive 2008/50/EC. This regulatory framework was subsequently amended by Legislative Decree No. 250/2012 and by Ministerial Decree of 26 January 2017 transposing Directive (EU) 2015/1480, which requires institutions responsible for the management of monitoring networks to participate in national quality assurance programmes organised by ISPRA, pursuant to Ministerial Decree of 4 February 2022, No. 67, which designates ISPRA as the National Reference Laboratory for air quality.

Participation of a laboratory in performance evaluation exercises through interlaboratory comparisons represents an operational tool within quality assurance and quality control (QA/QC) activities, supporting the demonstration of competence in the application of the measurement methods in use. The quality of laboratories’ analytical performance is assessed in terms of compliance or non-compliance with acceptability criteria established a priori by technical standards or, in some cases, by more stringent, purpose-oriented criteria adopted by the European Commission in comparable studies.

With reference to air quality monitoring measurements, comparison of performance between 2023 and 2025 does not indicate any substantial variations. The proportion of laboratories achieving acceptable evaluations is approximately 90% (91% and 88.4%, respectively). The total number of evaluations increased from 5,141 in 2023 to 11,187 in 2025.