Quality control is an inherent element of the services provided by ETI. Quality control encompasses all aspects of ensuring that the information documented in the final report is as accurate as possible. Elements of the ETI quality control program include:

• The use of EPA Protocol 1 reference calibration gases and ultra-high purity zero gases for analyzer calibration checks.

• The use of laboratory-grade reagents for wet chemistry methods.

• Strict compliance with calibration procedures specified by the EPA in the reference methods and by the manufacturer in the operation of each analyzer.

• Continuous strip chart and digital recording of all field data with frequent labeling.

• Review of all calculations and hand-checking to verify accurate data.

• Review of all final deliverable reports to ensure proper transcription of data.