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AQS Data Handling (Under the Hood) AQS Data Handling (Under the Hood)

AQS Data Handling (Under the Hood) - PowerPoint Presentation

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AQS Data Handling (Under the Hood) - PPT Presentation

AQS Conference August 23 2012 Robert Coats Topics Sample measurement acceptancerejection rules ½ MDL Substitution Rounding and truncating Allowed and disallowed qualifiers Summary statistics pollutant standards and exceptional data types ID: 702343

standard aqs conference data aqs standard data conference hour providence rhode island annual collection mdl frequency monitor summary completeness substitution parameter pollutant

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Slide1

AQS Data Handling(Under the Hood)

AQS Conference

August 23, 2012

Robert CoatsSlide2

Topics

Sample measurement acceptance/rejection rules

½ MDL Substitution

Rounding and truncatingAllowed and disallowed qualifiersSummary statistics – pollutant standards and exceptional data typesCollection frequencyData completeness

AQS Conference

2

Providence, Rhode IslandSlide3

Standard Value Calculation Process

AQS Conference

Providence, Rhode Island

3Slide4

Acceptance / Rejection Rules for Raw Data

Site-Monitor configuration:

Monitor exists and is active, monitor ownership, and etc.

Valid protocol: Combination of (parameter, method, unit, duration, collection frequency)No duplicatesValue between absolute min and absolute max for method

AQS Conference

Providence, Rhode Island

4Slide5

One-Half MDL Substitution

The default behavior for AQS is to perform ½ MDL substitution

As of this writing, there are 85 parameters where ½ MDL substitution does

not occur. They are listed at http://www.epa.gov/ttn/airs/airsaqs/manuals/codedescs.htm under the name parameters_nomdlsub.xls.If an alternate MDL is provided on the RD transaction, it is used instead of the Federal MDL for the MethodologyThe AQS Team has been directed to reverse the present configuration, so that no ½ MDL substitution is the default.

AQS Conference

Providence, Rhode Island

5Slide6

Rounding and Truncating

AQS allows values to be reported with up to 5 digits after the decimal as Raw Data.

AQS calculates a value in Standard Units for the parameter

The number of digits after the decimal is specified by the summary scale for the methodRounding or truncating is specified for the parameter.Depending on the parameter, AQS may compute a multi-hour rolling or block average (rounded or truncated).

AQS computes daily, quarterly, and annual statistics from the “Standard Value” or above average (not rounded or truncated).

The statistic (e.g., annual mean) used for comparison to the NAAQS standard is rounded or truncated as per 40 CFR Part 50.

AQS Conference

Providence, Rhode Island

6Slide7

Allowed and Disallowed Qualifiers

AQS maintains a table of qualifiers that are allowed for each parameter (posted at

http://www.epa.gov/ttn/airs/airsaqs/manuals/codedescs.htm

)For Regulatory parameters, the OAQPS monitoring staff have explicitly specified qualifiers that should be disallowed by parameterFor non-regulatory parameters, qualifiers allowed on request subject to approval by the OAQPS monitoring staff. (i.e., many are presently configured to be allowed, but not all. New ones can be requested (email AQSTeam@epa.gov)

AQS Conference

Providence, Rhode Island

7Slide8

Summaries and Pollutant Standards (1)

Each criteria pollutant has a set of NAAQS standards:

Lead: 3-Month Rolling Average, Quarterly Standard (old)

CO: 8-Hour Standard, and 1-Hour StandardSO2: 1-Hour Standard, Annual Standard, 24-Hour Standard, Secondary 3-Hour Standard, PM 10: 24-Hour Standard

PM 2.5: 24-hour Standard, Annual StandardNO2: 1-Hour Standard, Annual Standard

Ozone: 8-Hour 2008, 8-Hour 1997, 1-Hour StandardFor each standard, separate summary records are computed at each time period (daily, annual, etc.)Caveat: Only summaries that “make sense” are computed. See:

http://www.epa.gov/ttn/airs/airsaqs/manuals/pollutant_summaries.xls

AQS Conference

Providence, Rhode Island

8Slide9

Summary Statistics – Exceptional Data Types

For each summary, a record is created for each Exceptional Data type:

0: No Flagged Data

1: All Flagged values excluded from statistics2: Nothing excluded from statistics (i.e. ignore flags)5: Exclude regionally concurred exceptional event flagsThe net effect of the combination of Pollutant Standards and Exceptional Data types, is that there may be many records for a given summary period (e.g., Annual Summary)

AQS Conference

Providence, Rhode Island

9Slide10

Collection Frequency

Collection frequency shows up in two places in AQS – At the Monitor level as “Required Collection Frequency”, and for Raw Data as the “Collection Frequency Code” on the RD transaction.

The “Collection Frequency Code” from the RD transaction is deprecated; it is not used for any processing in AQS.

All completeness calculations, for other than hourly data, are controlled by the Monitor Required Collection Frequency.AQS Conference

Providence, Rhode Island

10Slide11

Data Completeness

Annual data completeness for criteria pollutants is determined as specified by 40 CFR Part 50.

For non-criteria pollutants with daily duration (or a longer time period), it is determined using the Monitor Required Collection Frequency (RCF).

In the past, there have been issues with the AQS Data Completeness Report, AMP430, for non-criteria pollutants. A change is in progress to this report, so that its results will exactly agree with the annual summaries for those pollutants. AQS Conference

Providence, Rhode Island

11Slide12

AQS Conference

Providence, Rhode Island

12

Questions?