Quality Assurance/ Quality Control Nate Herbst Southern Ute Indian Tribe

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

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?

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

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

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)

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

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%

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

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

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

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

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

monitoring without calibration 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

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

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

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

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

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

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

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

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

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

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

Summary Establish DQOs Develop QAPP Follow your 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