Quality Assurance/ Quality Control

1. Quality Assurance/ Quality Control Nate Herbst Southern Ute Indian Tribe

2. Intro to QA/QC • Getting good data requires many different steps • Data quality objectives (DQOs) developed • DQOs for ozone being developed • Measurement quality objectives (MQOs) for ozone exist • Analysis begun (after correct calibration) • QC checks performed • QA conducted

3. Data Quality Objectives (7 steps) • State problem • Define why monitoring is needed • Create team and purpose • Identify decision • What decision will be made with data? • Identify decision inputs • What data necessary to make decision? • Define boundaries • What are study area boundaries?

4. Data Quality Objectives (cont.) • Develop decision rule • What conditions will require action (action level)? • Specify decision error limits • What margin of error is allowable • Optimize monitoring design • Develop most cost-effective method of reaching DQOs • EPA hasn’t yet defined DQOs for ozone analysis

5. DQOs (cont.) Diagram of DQO steps (Diagram courtesy of U.S. Department of Energy – DQO homepage)

6. Measurement Quality Objectives (MQOs) Thanks to Melinda Ronca-Batista (ITEP) • EPA has ozone analysis MQOs • Use these in element 7 of your QAPP • MQOs in a nutshell • Shelter temperature kept between 20-30oC ± 2oC • Analyzer must be reference or equivalent method • Lower detectable limit 0.01ppm, noise 0.005ppm • Data completeness 75% of hourly values between 9:01am and 9:00pm (for the ozone season) • Transfer standard certification ±4% or 4ppb (whichever is greater)

7. MQOs (cont.) • Transfer standard re-certification to primary std.dev 1.5% • Local primary standard certification ±5% of reference • EPA reference photometer regression slope 1.00 ± 0.01 • Zero air free of O3 and anything that might react with O3

8. MQOs (cont.) • Ozone analyzer calibration • Z/S check zero ±10ppb, span ± 15% • 5pt calibration linearity error ±5% • Performance (NPAP) mean absolute difference ± 15% • Precision (quarterly) 95% CI < ±15% • Audits (annually) 95% CI < ±20%

9. Quality Assurance Project Plans (QAPPs) • Contain 24 “elements” • Element 7 is where MQOs go • Cut and paste from red book • Ensure data quality • Required by EPA • Developed by program approved by EPA • They must be followed! • No good if not followed

10. Documentation • Document everything!!! • Documentation in • Logbooks • Site folders • QA/QC field forms • Anywhere else you think is appropriate • QA/QC – document standard values and response

11. Documentation (cont.) • Document repairs, checks, fine tunes • Document site conditions • Document everything that could ever be important • Write only in pen (black if possible) • Cross out errors with a single line

12. Slope = rise over run m = slope b = intercept (where the trend-line crosses the Y axis) r2 close to 1 shows correlation Linearity

13. Instrument Calibration • Measurements require point of reference • Measurement without standard is impossible • Calibration involves setting instrument to known level • Calibrations performed fairly regularly • When monitoring is begun • When repairs or maintenance are performed • When precision checks or audits show need • Calibrations must be done correctly

14. Calibrations (cont.) • Calibration = setting analyzer to standard • Data only good within linear range (~0-0.400ppm) • Calibration followed by a 5-pt check • Analyzer must agree with standard at all 5 pts • Linearity error < 5% • See next slide on linearity • Monitoring begins after calibration Note: Never initiate monitoring without calibration

15. Not always necessary Can do 5-pt check Analyzer must be calibrated The r2 value and % differences for each point are unacceptable Pre-Calibration Check

16. Instrument Calibration • Calibrate instrument to the standard • Use calibration point near URL • Setting low produces large error at URL • Set standard to ~0.400 ppm • Let analyzer stabilize • Calibrate analyzer • Do new 5-pt check

17. Is analyzer response within 7% at each point? Would you put this analyzer online? Post-Calibration 5-pt Check

18. Quality Control (QC) • QC involves “in-house” verifications • Also referred to as precision checks • Verifications are comparisons between transfer standard and analyzer • Relative % difference within allowable margin? • Verifications determine monitoring repeatability • Standard deviation • Different types of verifications

19. QC (cont.) • Level 1: 40 CFR, Pt. 58, App. A, Table A-1 defines ozone verification requirements (for SLAMS) • Biweekly response check between 0.08 and 0.1 ppm • Comparison between analyzer and standard • Determines repeatability • Level 2: “extra” precision checks • Weekly “span level” (~80% URL) checks • Quarterly 5-pt checks • Determines analyzer performance trends

20. Quality Assurance (QA) • QA involves “external” checks • Referred to as “audits” • Audits involve comparison between transfer standard and analyzer • Accuracy levels must be within ±10% • Audits determine how close monitoring gets to actual values • Different types of audits

21. QA (cont.) • 40 CFR, Pt. 58, App. A, Table A-1 defines ozone audit requirements (for SLAMS) • Annual (and other) response checks at multiple points • 0.03-0.08 ppm • 0.15-0.2 ppm • 0.35-0.45 ppm • Comparison between analyzer and external standard • Audits should include zero check

22. QA (cont.) • Different types of audits • By reporting organization (RO) certified by RO • By RO certified by other than RO • By other than RO certified by other than RO

23. Precision & Accuracy (P&A) Data • Precision data come from biweekly precision checks • Accuracy data come from annual and other audits • P&A data validate ambient data • P&A data must be included in AQS data submittals

24. Siting Criteria • Data quality depends on correct siting of all instrumentation • Specific instrument siting guidelines • Following guidelines is vital part of quality assurance and control • We’ll learn more about these guidelines in the next presentation

25. Summary • Establish DQOs • Develop QAPP • Get it approved by EPA • Follow your QAPP • Conduct bi-weekly precision checks • Conduct level 2 checks to follow monitor trends • Participate in annual audits and others if possible • Data quality will be guaranteed