Methane emissions from anaerobic digestion sites can occur through poorly performing breather valves, incorrect pressure and vacuum settings, damaged seats, poor maintenance history or unsuitable valve selection. These losses create environmental, safety and operational risks, while weakening compliance evidence under the Industrial Emissions Directive. This paper explains how operators can support Appropriate Measures Section 8.11 by demonstrating that emissions from pressure relief systems are understood, controlled and regularly assessed. Drawing on Assentech's experience across AD and biogas sites, it focuses on the inspection, removal, servicing and API 2000 testing of breather valves used on digesters and tanks. Using Vent-Less testing, leak detection surveys and traceable reporting, operators can identify leaking valves, verify set points, quantify methane losses and produce defensible evidence for regulators. This supports risk based maintenance, reduced fugitive emissions, improved plant efficiency and stronger environmental compliance.