Surface ozone is one of the major air pollutants, with mitigation strategies to reduce human exposure requiring continuous monitoring and reliable measurement data. The accuracy of ground-level ozone measurement results is about to improve, based on more accurate measurements of the cross section of ozone from the international metrology community. A campaign to adopt the new more accurate ozone cross section value throughout the world at the same time was initiated following the BIPM workshop on Accurate Monitoring of Surface Ozone (2020). This is being coordinated by the CCQM Task Group for Ozone Cross-Section, with input from key stakeholders including environmental agencies, regulators, standards writing bodies, instrument manufacturers, air quality laboratories and networks, atmospheric scientists and others.

A dedicated webpage has been established to inform the stakeholder community of the change and provide guidance on implementation. Interested parties are encouraged to Sign up now to be alerted when additional documentation becomes available.

The implementation of the new ozone absorption cross-section value is planned to start on 1 January 2025 with a transitionary period until 1 January 2026, at which time all stakeholders should adopt the new cross section value.

Ozone webpage