Virtual and Field Audit Resources

EPA conducts electronic data audits, virtual (desk) audits, and field (on-site) audits of power plants’ emissions monitoring systems and practices. EPA also observes performance tests of the monitoring systems. These audits and observations are intended to assess how power plants implement the part 75 emission monitoring and quality requirements, and to ensure systems are properly documented. EPA provides the following resources to help power plants prepare for audits and conduct self audits and for state, local, and tribal air personnel to use as resources in their own audits of emission monitoring systems and practices. Questions can be directed to the appropriate contact on the EPA Regional/State CEM contacts list (pdf) (341.91 KB, June 17th, 2024) .

Virtual (Desk) Audits

The Part 75 Continuous Emissions Monitoring (CEMS) Virtual (Desk) Audit Guide details the procedures for conducting virtual audits of Part 75 monitoring systems. The guide includes procedures for virtual audits, checklists for document and photo requests, and standard audit questions.

• The Part 75 Continuous Emissions Monitoring (CEMS) Virtual (Desk) Audit Guide (pdf) (415.61 KB, May 5, 2023)

Field Audits

The Part 75 Continuous Emissions Monitoring System (CEMS) Field Audit Manual details recommended procedures for conducting field audits of Part 75 monitoring systems. The manual includes techniques for the on-site inspection and records review, methods for performance test observation, and guidelines for report preparation. EPA has designed the audit procedures in this document so that personnel with varying levels of experience can use them. Appendix A of the manual also provides checklists that can be used as a guideline to ensure that all necessary data are obtained during facility inspection. EPA also provides an “abbreviated” audit guide for situations when there is insufficient time for a comprehensive part 75 field audit.

• Part 75 CEMS Field Audit Manual (pdf) (1.4 MB, July 16, 2003)
• Part 75 CEMS Field Audit Manual: Appendix A Example Audit Forms and Guide Sheets (docx) (216.78 KB, July 16, 2003)
• Abbreviated part 75 CEMS audit (pdf) (164.18 KB, July 15, 2019)
• Part 75 Audit Spreadsheet (xlsm)

Stack Test Observations

The Observer's Checklists includes technical guidance and checklists for observing stack gas flow tests.

• Observer's Checklists for Test Methods 2F, 2G, and 2H (pdf) (192.64 KB)