Monitoring of oxygen concentration in the Contracting Parties of HELCOM is described on a general level in the HELCOM Monitoring Manual in the sub-programme: Water column chemical characteristics.
Specific monitoring guidelines have been agreed in the HELCOM COMBINE guideline. The analytical requirements are specified, including definition of the type and nature of the sample and its environment, concentration range of interest and permissible tolerances in analytical error (Part B Annex B3 in the HELCOM COMBINE manual).
The monitoring activities relevant to the indicator that are currently carried out by HELCOM Contracting Parties are described in the HELCOM Monitoring Manual Sub-programme: monitoring concepts table.
Regional monitoring is considered to be sufficient for the purposes of the indicator evaluation.