Technical System Audits

This page last reviewed January 07, 2011

A system audit is an on-site inspection and review of a monitoring organization's entire program.  The total measurement system is reviewed (sample collection, sample analysis, data processing, etc.).  The audit includes a review of staff, procedures, facilities, and documentation to assure compliance with federal air quality monitoring, quality assurance, siting, and data reporting regulations.



System audits of a monitoring organization operating national ambient air monitoring stations (NAMS) are the responsibility of the United States Environmental Protection Agency (U.S. EPA).  The U.S. EPA may negotiate with private contractors or the Air Resources Board (ARB) to conduct a portion or all of these NAMS system audits.  In addition to system audits of organizations operating NAMS, the QAS of the ARB's Monitoring and Laboratory Division conducts routine system audits of those organizations operating SLAMS without a subset of NAMS, and selected private contractors.


System audit procedures used by QAS auditors are in accordance with those stipulated in the U.S. EPA's Quality Assurance Handbook (EPA-600/4-77-022a, Section2.0.11).  QAS modifies the questionnaires and check sheets in reference to the type of system audit being conducted.  Audit questionnaires and check sheets are mailed to the audited organization in advance of the actual on-site visit by the auditors. The monitoring organization is to complete the questionnaires and check sheets and return them to the auditors at least one week prior to the on-site visit.  Each system audit will be documented in a System Audit Report which shall be sent to the audited organization.  That report shall include the findings of the auditors and, whenever necessary, suggested corrective actions. It is the responsibility of the audited organization to correct all deficiencies and report such corrections to the ARB's Planning and Technical Support Division's Air Quality Data Review Section and U.S. EPA's Air Quality Systems quality assurance coordinators.

System Audit Components

  • Assessment of Staff: 
    1. Background and education, 
    2. Chain of command regarding description of assignments and specific duties, 
    3. Continued training, and 
    4. Level of staffing. 
  • Assessment of Facilities:
    1. Laboratory and support facilities, 
    2. Monitoring sites with respect to stated siting criteria and representativeness requirements, 
    3. Calibration and audit frequency, and 
    4. Documentation. 
  • Assessment of Data and Document Control:
    1. Chain of custody, 
    2. Validation and processing procedures, 
    3. Reporting formats, 
    4. Storage, and 
    5. Documentation. 
  • Assessment of the Quality Control Programs: 
    1. Adequacy of procedures, and 
    2. Adherence to procedures.

Program Contact - Patrick Rainey