We: • Carried out interviews with key personnel to understand the systems and controls in place during the reporting period • Assessed the systems, processes, and controls to collate, aggregate, validate and report the data • Checked the relevant conversion factors and GHG emission calculations • Reviewed any matters showing significant variations from prior years • Reviewed the appropriateness of the GHG emissions and other environmental data provided by Illumina and their third-party data management system service provider • Tested a sample of records against underlying records The relative effectiveness and significance of specific control procedures at Illumina and their effect on assessment of control risk at a facility level are dependent on their interaction with the controls and other factors present at individual facilities.