CASTNET Independent Audit Program

An independent auditor visits each CASTNET site at least once every other year to perform a Field Systems Audit (FSA). Regulatory ozone monitoring sites are audited annually by an independent auditor or a local monitoring agency. Performance evaluation results are loaded into EPA's Air Quality System (AQS) database routinely.

The Quality Assurance Project Plan (QAPP) and Standard Operating Procedures for the independent audits are available below. The quarterly and annual audit reports are also provided below.
 

• First Quarter Audit Report - 2025 (pdf) (1.05 MB, April 2025)
• Fourth Quarter Audit Report - 2024 (pdf) (1.72 MB, January 2025)
• Third Quarter Audit Report - 2024 (pdf) (1.73 MB, December 2024)
• Second Quarter Audit Report - 2024 (pdf) (1.77 MB, November 2024)
• First Quarter Audit Report - 2024 (pdf) (607.56 KB, April 2024)
• Fourth Quarter Audit Report - 2023 (pdf) (4.99 MB, January 2024)
• Second Quarter Audit Report - 2023 (pdf) (1.28 MB, July 2023)
• Fourth Quarter Audit Report - 2022 (pdf) (2.53 MB, February 2023)
• Third Quarter Audit Report - 2022 (pdf) (908.55 KB, February 2023)
• Second Quarter Audit Report - 2022 (pdf) (1.28 MB, July 2023)
• First Quarter Audit Report - 2022 (pdf) (457.84 KB, April 2022)
• Fourth Quarter Audit Report - 2021 (pdf) (3.31 MB, March 2022)
• Third Quarter Audit Report - 2021 (pdf) (2.59 MB)
• Second Quarter Audit Report - 2021 (pdf) (3.43 MB)
• First Quarter Audit Report - 2021 (pdf) (1.4 MB)
• CASTNET Annual Report - 2020 (pdf) (4.28 MB)
• Fourth Quarter Audit Report - 2020 (pdf) (1.73 MB)
• Third Quarter Audit Report - 2020 (pdf) (2.63 MB)
• Second Quarter Audit Report - 2020 (pdf) (1.28 MB)
• First Quarter Audit Report - 2020 (pdf) (370.62 KB)
• CASTNET Annual Report - 2019 (pdf) (7.34 MB)
• Fourth Quarter Audit Report - 2019 (pdf) (2.49 MB)
• Third Quarter Audit Report - 2019 (pdf) (2.94 MB)
• Second Quarter Audit Report - 2019 (pdf) (1.82 MB)
• First Quarter Audit Report - 2019 (pdf) (946.6 KB)
• CASTNET Annual Report - 2018 (pdf) (6.56 MB)
• Fourth Quarter Audit Report - 2018 (pdf) (1.9 MB)
• Third Quarter Audit Report - 2018 (pdf) (1.28 MB)
• Second Quarter Audit Report - 2018 (pdf) (1.33 MB)
• First Quarter Audit Report - 2018 (pdf) (304.82 KB)
• CASTNET Annual Report - 2017 (pdf) (10.58 MB)
• Fourth Quarter Audit Report - 2017 (pdf) (1.71 MB)
• Third Quarter Audit Report - 2017 (pdf) (2.03 MB)
• Second Quarter Audit Report - 2017 (pdf) (2.24 MB)
• First Quarter Audit Report - 2017 (pdf) (983.42 KB)
• CASTNET Annual Report - 2016 (pdf) (6.84 MB)
• Fourth Quarter Audit Report - 2016 (pdf) (1.09 MB)
• Third Quarter Audit Report - 2016 (pdf) (1.27 MB)
• Second Quarter Audit Report - 2016 (pdf) (1.05 MB)
• Audit Program Annual Report - 2015 (pdf) (6.92 MB)
• Fourth Quarter Audit Report - 2015 (pdf) (8.82 MB)
• Third Quarter Audit Report - 2015 (pdf) (3.38 MB)
• First Quarter Audit Report - 2015 (pdf) (1.3 MB)
• Audit Program Annual Report - 2014 (pdf) (3.81 MB)
• Fourth Quarter Audit Report - 2014 (pdf) (1.6 MB)
• Third Quarter Audit Report - 2014 (pdf) (1.82 MB)
• Second Quarter Audit Report - 2014 (pdf) (2.39 MB)
• First Quarter Audit Report - 2014 (pdf) (1.23 MB)
• Audit Program Annual Report - 2013 (pdf) (6.54 MB)
• Third Quarter Audit Report - 2013 (pdf) (1.98 MB)
• Second Quarter Audit Report - 2013 (pdf) (2.25 MB)
• First Quarter Audit Report - 2013 (pdf) (1.77 MB)
• Audit Program Annual Report - 2012 (pdf) (11.36 MB)
• Audit Program Annual Report - 2011 (pdf) (207.05 KB)
• Audit Program Annual Report - 2007 (pdf) (211.01 KB)
• Audit Program Annual Report - 2006 (pdf) (226.25 KB)
• Audit Program Annual Report - 2005 (pdf) (184.09 KB)
• Audit Program Quality Assurance Project Plan (QAPP) (pdf) (363.37 KB)
• Audit Program Standard Operating Procedures (SOPs) (pdf) (389.02 KB)