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Quality Assurance Project Plan for the Federal
National Performance Audit Program (NPAP)
for Criteria Pollutant Gases
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EPA-454/B-19-012
June 2021
Quality Assurance Project Plan for the Federal National Performance Audit Program (NPAP)
for Criteria Pollutant Gases
U.S. Environmental Protection Agency
Office of Air Quality Planning and Standards
Air Quality Assessment Division
Research Triangle Park, NC
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NPAP QAPP
Revision No.: 6
June 2021
EPA-454/B-19-012
Foreword
U.S. Environmental Protection Agency (EPA) policy per EPA Order CIO 2105 requires that all
projects involving the generation, acquisition, and use of environmental data be planned and
documented and have an Agency-approved Quality Assurance Project Plan (QAPP) before the
start of data collection. The primary purpose of the QAPP is to provide a project overview,
describe the need for the measurements, plan, and define quality assurance/quality control
(QA/QC) activities to be applied to the project, all within a single document.
This document represents the QAPP for the environmental data operations involved in EPA's
National Performance Evaluation Program (NPEP) for the National Ambient Air Quality
Standards (NAAQS) gas monitoring network: the National Performance Audit Program (NPAP)
for through the probe (TTP) audit methods. This QAPP was developed by incorporating the
following EPA monitoring and QA regulations and guidance:
• 40 Code of Federal Regulations (CFR) Part 50, Appendices A, C, D, and F
• 40 CFR Part 58, Appendices A, C, and E.9
• EPA QA/R-5, EPA Requirements for Quality Assurance Project Plans
• EPA QA/G-5, Guidance for Quality Assurance Project Plans
• EPA QA/G-9, QA00 update, Guidance for Data Quality Assessment: Practical Methods for
Data Analysis.
Pertinent elements of the EPA's QAPP guidance (EPA QA/G-5) are incorporated into this
QAPP.
This QAPP and related NPAP standard operating procedures (SOPs) are accessible via the
EPA's Ambient Monitoring Technology Information Center (AMTIC) website (available at
https://www.epa.gov/amtic/national-performance-audit-program-npap-gaseous-monitoring). The
documents may be read and printed using Adobe Acrobat™ Reader software, freeware that is
available on many Internet sites, including the EPA's web site.
This QAPP may be revised as program objectives and implementation procedures evolve.
Comments may be sent to:
Trisha Curran
Office of Air Quality Planning and Standards
AQAD/AAMG (C304-06)
Research Triangle Park, NC 27711
Phone: (919) 541-5619
E-mail: curran.trisha@epa.gov
The document mentions trade names and/or brand names. Any mention of corporation
names, trade names, or commercial products does not constitute endorsement or
recommendation for use.
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NPAP QAPP
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A. PROJECT MANAGEMENT
A1 QA Project Plan Approval
Title: Quality Assurance Project Plan for the Federal National Performance Audit Program
(NPAP) for Criteria Pollutant Gases
The attached Quality Assurance Project Plan (QAPP) for the Federal National Performance
Audit Program for Criteria Pollutant Gases is hereby recommended for approval and commits
the participants of the program to follow the elements described within.
OAQPS
Region 1
Region 2
Region 3
Region 4
Region 5
Region 6
Region 7
Region 8
Region 9
Region
10
Noah, Greg
Signature:
Name:
CHRISTOPHER ST.
Signature: GERMAIN
Name:
Mustafa, Mustafa
Digitally signed by Noah, Greg
Date: 2021.09.1408:59:22 -04'00' Date'
Digitally signed by CHRISTOPHER ST.
GERMAIN
Date: 2021.07.22 07:34:38 -04'00' Date:
Digitally signed by Mustafa, Mustafa
Date: 2021.08.13 10:35:18-04'00'
Date:
LORETTA HYDEN
Digitally signed by LORETTA HYDEN
Date: 2021.08.13 11:57:11 -04'00'
Date:
Signature:
Name:
Signature:
Name:
Signature:
Name: Digitally signed by Hamilton,
Hamilton, Scottscott
Signature: Date:202i.08.i8 07:26:2i-os'oo1 Date:
Name:
Harris, Keith
Digitally signed by Harris, Keith
Date: 2021.08.17 17:03:16 -04'00' Date'
Signature:
Name:
Signature:
Name:
CLARENCE JACKSON
Digitally signed by CLARENCE JACKSON
DN:c=US, o=U.S. Government, ou=Environmental Protection Agency,
cn=CLARENCE JACKSON, 0.9.2342.19200300.100.1.1 =68001003655920
Date: 2021.08.18 15:28:49 -05'00'
THIEN BUI
Digitally signed by THIEN BUI
Date: 2021.08.19 11:25:08 -0500'
Date:
Date:
Digitally signed by JOSHUA
JOSHUA RICKARD RICKARD
Signature: Date:202i.os.i9 12:23:04-06'oo' Date:
Name. Digitally signed by Audrey L
Audrey L Johnson Johnson
Signature: Date:2021.08.31 11:4i:38-Q7loolDate:
Name:
Signature:
Name:
Wallace, Henry
Digitally signed by Wallace, Henry
Date: 2021.09.10 08:18:16 -0700'
Date:
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NPAP QAPP
Revision No.: 6
June 2021
EPA-454/B-19-012
Acknowledgments
This QAPP is the product of the combined efforts of EPA's Office of Air Quality Planning and
Standards (OAQPS); EPA Regional offices; and State, Local, and Tribal (SLT) organizations.
Greg Noah of OAQPS led the effort to revise this QAPP. The following individuals are
acknowledged for their contributions:
EPA Regions
Region:
1
Chris St. Germain
2
Avraham Teitz
3
Loretta Hyden
4
Mike Crowe
5
Scott Hamilton
6
Clarence Jackson
7
Thien Bui
8
Joshua Rickard
9
Larry Biland
Mathew Plate
10
Christopher Hall
Office of Air Quality Planning and Standards
Greg Noah
Trisha Curran
Douglas Jager
Battelle under EPA Contract EP-D-13-005
Douglas Turner
Mitchell Lawrence
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NPAP QAPP
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June 2021
EPA-454/B-19-012
Al.l Document Control List
Revision Changes
1. Converted to R-5 format
(A) See Table of Contents
2. Change from National Environmental Research Laboratory (NERL) to OAQPS in
1998
(A) Coordinator to Manager
(1) Shifted some coordinator's duties to contractor
(a) Moved procedures from the QA Plan and SOP 001 to the
contractor
(2) NERL laboratory to EPA Region 7 laboratory
3. Modified to include National Air Toxics Trends Stations (NATTS) Proficiency
Testing Program in 2005
4. Modified in 2006 to include through the probe (TTP) and eliminating the mailed
NPAP Audit Delivery for Gaseous Criteria Pollutants program
5. Document revised to include details of audit conduct and recording of data through
the Performance Evaluation AQS Tool (PEAT) process.
6. Additional changes following review/comment by the NPAP community. Inclusion of
details for the following: flow-based audit quality procedures, palladium scrubber
zero air assessments, and audit system verification acceptance criteria. Additionally,
removed EPA Region 2 as an interlaboratory comparison laboratory and added EPA
Region 4 as a verification laboratory.
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NPAP QAPP
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ACRONYMS
AAMG
Ambient Air Monitoring Group
AA-PGVP
Ambient Air Protocol Gas Verification Program
AMTIC
Ambient Monitoring Technology Information Center, Website on the EPA TTN
(Technology Transfer Network)
API
Advanced Pollution Instruments
AQAD
Air Quality Analysis Division
AQS
Air Quality System
BLM
Bureau of Land Management
BOA
back of the analyzer
CAMD
Clean Air Markets Division
CAP
corrective action plan
CASTNET
Clean Air Status and Trends Network
CAT
corrective action tracking
CFR
Code of Federal Regulations
CO
carbon monoxide
COA
certificate of analysis
COR
Contracting Officer Representative
DAS
data acquisition system
EPA
Environmental Protection Agency
FBA
flow-based audit
FEM
Federal Equivalent Method
FEP
fluorinated ethylene propylene
FS
field scientist
GPT
gas phase titration
ID
identification
IT
information technology
MFC
mass flow controller
MVA
measured verification audit
NAAQS
National Ambient Air Quality Standards
NERL
National Environmental Research Laboratory (Part of EPA Office of Research
and Development)
NIST
National Institute of Standards and Technology
NO
nitric oxide
no2
nitrogen dioxide
NOx
oxides of nitrogen (sum of nitic oxide and nitrogen dioxide)
NPAP
National Performance Audit Program
NPEP
National Performance Evaluation Program
NPS
National Park Service
03
ozone
OAQPS
Office of Air Quality Planning and Standards
PAMS
Photochemical Assessment Monitoring Stations
Pb
lead
Pd
palladium
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NPAP QAPP
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PE
performance evaluation
PEAT
Performance Evaluation AQS Tool
PEP
Performance Evaluation Program
ppb
part(s) per billion
ppm
part(s) per million
PQAO
primary quality assurance organization
PTFE
polytetrafluoroethylene
QA
quality assurance
QAPP
quality assurance project plan
QC
quality control
RTP
Research Triangle Park, North Carolina
SIP
State Implementation Plan
SLAMS
State and Local Air Monitoring Station
SLT
State, Local, and Tribal
S02
sulfur dioxide
SOP
standard operating procedure
SPM
Special Purpose Monitor
SRP
standard reference photometer
STAG
state and tribal assistance grants
THC
total hydrocarbons
TOPO
Task Order Project Officer
TSA
technical systems audit
TTP
through the probe
ZAG
zero air generator
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NPAP QAPP
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A1.2 Table of Contents
Section Page
Foreword 2
A. PROJECT MANAGEMENT 3
A1 QA Project Plan Approval 3
A1.1 Document Control List 5
A1.2 Table of Contents 8
A2 Distribution List 11
A3 Project/Task Organization 11
A3.1 NPAP Roles and Responsibilities 11
A3.1.1 OAQPS NPAP Lead 11
A3.1.2 Regional NPAP Lead 12
A3.1.3 PQAO NPAP Lead 12
A3.1.4 Field Scientist 13
A3.1.5 QA Support Contractor 13
A3.1.6 State, Local, and Tribal Monitoring Organizations 13
A3.1.7 EPA Region 4 and Region 7 Verification Laboratories 14
A3.1.8 Clean Air Status and Trends Network (CASTNET) Lead 14
A4 Problem Definition/Background 14
A5 Project Description and Schedule 17
A5.1 NPAP TTP Description 17
A5.2 NPAP Site Selection and Schedule 19
A5.2.1 Site Selection 19
A5.2.2 NPAP Equipment Preparation Schedule 20
A5.2.3 TTP Audit Scheduling 21
A5.2.4 Pre-Audit C ommuni cati on S chedul e 21
A5.2.5 Schedule for Audit Reporting to AQS 22
A5.3 Field Scientist Responsibilities 22
A6 Quality Objectives and Criteria for Measurement 22
A6.1 Audit Devices and Materials 23
A6.2 Bias of Audit Stock Standard Gases 25
A6.3 Confirming Challenge Gas Concentrations 25
A6.4 Completeness 26
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A6.5 Characterizing Monitoring Station Bias 26
A7 Training Requirements and Certification 27
A7.1 Self-Implementing PQAOs 28
A8 Documentation and Records 29
A8.1 Equipment and Standards Certification Records 29
A8.2 Challenge Gas Generation and Verification Records 29
A8.3 PEAT Records 30
A8.4 Audit Results Report 30
B. MEASUREMENT/DATA ACQUISITION 32
B1 Sampling Process Design - Concentration Selection, Generation, Verification, and
Delivery of Challenge Gases 32
B1.1 Selecting Challenge Gas Concentrations 32
B1.2 Generating Challenge Gases 34
B1.2.1 Ozone Audit 34
B1.2.2 Blended Gas Audit 34
B1.3 Verifying Challenge Gas Concentrations for Measured Verification Audits 35
B1.4 Delivery of Challenge Gas 36
B2 Sampling Methods Requirements 37
B2.1 Stability of Challenge Gas Concentrations 37
B2.1.1 Measurement Verification Audit Gas Concentration Stability 37
B2.1.2 Flow-Based Audit Gas Concentration Stability 38
B2.2 Environmental Conditions Measurements 38
B3 Sample Handling and Custody 38
B4 Analytical Methods 39
B5 Quality Control Requirements 39
B6 Instrument/Equipment Testing, Inspection, And Maintenance Requirements 39
B7 Instrument Calibration and Frequency 40
B8 Inspection/Acceptance Requirements for Supplies and Consumables 40
B9 Data Acquisition Requirements (Non-Direct Measurements) 40
B10 Data Management 40
B10.1 Overview of Data Management 40
B10.2 Data Processing and Reporting 41
B10.3 Unacceptable Results 41
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B10.4 Data Reports 42
C. ASSESSMENT/OVERSIGHT 43
C1 Assessments and Response Actions 43
C1.1 Performance Audits 43
C1.1.1 Performance Audit of NPAP Audit Systems 43
C1.1.2 Verification of Audit Systems 43
CI. 1.3 Technical Systems Audits of NPAP Regional Field Scientist Contractors 44
CI. 1.4 Independent Assessment of EPA Gas Certification Laboratories 44
CI. 1.5 Independent Assessment of EPA Field Scientists 44
C1.2 C orrective Acti on 45
C1.2.1 Monitoring Agency Corrective Actions 45
CI.2.2 NPAP Field Scientist and Support Laboratory Corrective Actions 45
C1.3 Assessment (TS A) Reports 45
C2 Reports to Management 45
D. DATA VALIDATION AM) USABILITY 48
D1 Data Review, Verification, and Validation Requirements 48
D2 Validation and Verification Methods 49
D3 Reconciliation with User Requirements 50
APPENDIX A 52
Tables
Table A6-1. Certification and Verification Specifications for Audit Devices and Materials 23
Table A6-2. Acceptance Criteria for NPAP TTP Audits 26
Table B1-1. Expanded NPAP Audit Levels and Associated Concentrations 34
Table C2-1. List of Reports Required for NPAP 46
Table Dl-1. NPAP TTP Audit Validation Criteria 48
Table Dl-1. NPAP TTP Audit Validation Criteria (continued) 49
Figures
Figure A3-1. NPAP Communication and Responsibility Structure 14
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A2 Distribution List
Role
Organization
Audit Support Contractor(s)
Support Contractor's Program Manager
Contract Project Officer
OAQPS NPAP Lead
Regional NPAP Leads
AAMG QA Team Leader
QA Manager
Self-Implementing PQAO NPAP Leads
Contractor
Contractor
EPA, OAQPS-OD, COR Contracts
EPA, OAQPS
EPA, Regional Offices
EPA, OAQPS
EPA
State, Local, and Tribal Monitoring
Organizations
EPA Region 4 and 7 Verification Laboratories
EPA
A3 Project/Task Organization
The NPAP is conducted in the 10 EPA Regions by EPA Regional staff, government contractors,
or independent employees (for self-implementing primary quality assurance organizations
[PQAOs]) who are trained and certified by EPA for NPAP through the probe (TTP) audits.
Third-party support for verification of gaseous audit standard materials is provided as needed
from EPA Region 7. Audit support is provided by EPA OAQPS in concert with a quality
assurance (QA) support contractor responsible for audit testing, training, and, as available,
certification.
The EPA NPAP Research Triangle Park (RTP) Task Order Project Officer (TOPO), who serves
as the "OAQPS NPAP Lead," reports to the OAQPS/Air Quality Analysis Division
(AQAD)/Ambient Air Monitoring Group (AAMG) Group Leader. The OAQPS NPAP Lead is
responsible for overseeing all program activities. The OAQPS NPAP Lead works with the 10
EPA NPAP Regional Leads to ensure the participation of the state, local, private, and tribal
agency participants within their respective Regions. An organization chart detailing the current
roles within the NPAP is maintained by the OAQPS NPAP Lead.
The EPA Region 4 and Region 7 verification laboratories conduct performance evaluations of
the Regional NPAP audit equipment systems and verifications of concentrations of standard gas
cylinders on behalf of OAQPS.
A3.1 NPAP Roles and Responsibilities
A3.1.1 OAQPS NPAP Lead
The OAQPS NPAP Lead's role is to implement and manage the NPAP at the national level. This
individual has the responsibility of creating, implementing, and maintaining the quality systems
documents for the program including the NPAP QAPP, supporting standard operating
procedure(s) (SOPs), and providing technical direction that the program requires. An ancillary
responsibility of the OAQPS NPAP Lead is to manage the QA support contractor who serves the
NPAP. To promote and maintain consistency across the NPAP, the OAQPS NPAP Lead serves
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as a point of contact for the Regional NPAP Leads and NPAP Field Scientists (FSs). The
OAQPS NPAP Lead also plays a role by interacting with the Regions to obtain funding for the
NPAP audits and organizes training activities for the NPAP to ensure experienced and new
NPAP FSs as well as Regional NPAP Leads acquire and maintain appropriate skills. The
OAQPS NPAP Lead is also responsible for assessing the NPAP data and communicating the
results to the NPAP community and the EPA Regions. The OAQPS NPAP Lead is responsible
for maintaining a small complement of backup instruments and equipment employed in the
NPAP which are available for loan to Regions on a short-term basis to cover equipment failures.
A3.1.2 Regional NPAP Lead
Regional NPAP Leads implement the NPAP at the Regional level. There is a Regional NPAP
Lead for each of the 10 EPA Regions. The specific details of the Regional NPAP Lead depend
on the configuration of the NPAP in each Region. Minimally, the Regional NPAP Lead is
responsible for ensuring that the required NPAP TTP audits for monitoring sites within the
Region are performed and reported to the Air Quality System (AQS) according to the schedule
prescribed in this QAPP and 40 CFR Part 58, Appendix A and that developments to the NPAP
within the Region are communicated to the OAQPS NPAP Lead. Such developments may
include details for staffing or training needs, financial needs, equipment and supplies needs,
and/or other technical or administrative developments that impact implementation of the NPAP.
Regional NPAP Leads are to maintain expertise with the conduct of the NPAP and are to stay
current on the status of monitoring site audit performance and resulting necessary corrective
actions. Once a TTP audit is completed and is staged for entry into AQS, the NPAP Regional
Lead is to review the data collected for the NPAP TTP audit(s) conducted in their Region and
approve or reject the audits within AQS.
Regional NPAP Leads in some Regions also serve as FSs and conduct TTP audits (e.g., Regions
1, 2, and 7), and as such also maintain the responsibilities for FSs listed in Section A3.3. Regions
for which the Regional NPAP Lead does not also serve as a FS typically utilize a contractor to
conduct the NPAP TTP audits. In such cases where a contractor FS conducts the TTP audits, the
Regional NPAP Lead is responsible for managing the contractor performance unless there is an
alternate arrangement. In all cases, the Regional NPAP Lead serves as a technical resource for
conducting NPAP TTP audits and maintains technical expertise in the equipment and procedures
for TTP audits.
The Regional NPAP Lead is also responsible for overseeing the conduct of audits for self-
implementing PQAOs within their Region. In this role, they are responsible for ensuring that the
required number of audits is scheduled and performed annually, as well as ensuring technical
support and training are available for PQAO staff as needed for maintaining a properly
functioning NPAP-equivalent program.
A3.1.3 PQAO NPAP Lead
The PQAO NPAP Lead is the individual with overall responsibility for managing the NPAP for
a PQAO self-implementing the NPAP. The PQAO NPAP Lead is analogous to the Regional
NPAP Lead described in Section A3.1.2; however, the PQAO NPAP Lead reports developments
with the PQAO NPAP to the Regional NPAP Lead. Developments in the PQAO TTP audit
program may include equipment or supplies failures or problems, staffing issues, or other similar
issues that may involve risk to completion of the required NPAP audits for the calendar year for
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the PQAO. The PQAO NPAP Lead is independent of the routine monitoring processes within
the PQAO, including the annual performance evaluation (PE) TTP audits the monitoring
organization is required to perform per Section 3.1.2 of 40 CFR Part 58, Appendix A. The
PQAO NPAP Lead is responsible for ensuring the PQAO self-implementing program meets the
requirements in this QAPP such that the PQAO program demonstrates equivalent performance to
the Federal NPAP in accordance with the NPAP Adequacy/Independence Criteria Memo dated
July 2008 (available at: https://www.epa.gov/sites/production/files/2020-
10/documents/npapadequacv072408.pdf) and the National Performance Audit Program, PM2.5.
PM10-2.5, and Lead Performance Evaluation Program Implementation Decision Memorandum for
each calendar year. The PQAO NPAP Lead is responsible for managing the PQAO independent
FSs and ensuring that the TTP audits are conducted according to the annual established schedule
and are reported to AQS within the specified timeframe.
A3.1.4 Field Scientist
The FS is the individual conducting the NPAP TTP audit in the field - in this QAPP, the term
"auditor" and "FS" are used interchangeably. The FS may be a Regional EPA staff member
(such as a Regional NPAP Lead), contractor auditor, or a monitoring agency staff member (for
self-implementing PQAOs) and they report to the Regional NPAP Lead or the PQAO NPAP
Lead, as appropriate. The FS responsibilities are to conduct the NPAP TTP audits and report the
results to AQS according to the specifications and schedule prescribed in this QAPP. Contractor
FSs may also be required to abide by contractual specifications as defined by contracts with the
EPA Region(s) which they support. FSs are responsible for ensuring: sufficient supplies
(including standard gases) are available, equipment and instruments are calibrated and
maintained, and that problems or issues that may impact successful completion of the scheduled
audits are communicated promptly to the Regional NPAP Lead or PQAO NPAP Lead, as
appropriate.
A3.1.5 QA Support Contractor
The QA Support Contractor provides technical support to the OAQPS NPAP Lead. Such
technical support may include development and revision of quality systems documents,
development and presentation of training materials and/or conducting training seminars,
conducting various audits of NPAP processes and collected data, and compilation of QA data
and preparation of reports to organize and summarize information important to the conduct and
administration of the NPAP as defined in the appropriate contract. The QA Support Contractor
should maintain expertise in policies, procedures, and equipment needed to accomplish the
NPAP goals.
A3.1.6 State, Local, and Tribal Monitoring Organizations
The SLT monitoring organizations are responsible for ensuring their monitor status and
monitoring site data within AQS are current for sites reporting criteria pollutant gas data for
determining design values for regulatory purposes. Monitoring organizations are also responsible
for coordinating with Regional NPAP Leads, PQAO NPAP Leads, and/or FSs to schedule TTP
audits, to ensure monitoring organization staff are available to provide measurements during
conduct of TTP audits, and to ensure that FSs can safely access monitoring sites.
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A3.1.7 EPA Region 4 and Region 7 Verification Laboratories
The EPA Region 4 and Region 7 Verification Laboratories are responsible for certifying
calibration gases and calibrating a portion of the ozone analyzers (Level 2 ozone standards)
employed in the NPAP. Their role is to serve as calibration verification laboratories for the third-
party verification of vendor-prepared standard gases that are diluted as challenge gases during
TTP audits and gases employed to calibrate NPAP instruments when conducting TTP audits.
These verification laboratories also serve to verify NPAP audit equipment systems. This
independent verification step assures the performance of the entire TTP instrument system and
connection configuration. In this role, these verification laboratories certify equipment and serve
as comparison laboratories for verification of NPAP audit equipment systems that are in use in
each Region or self-implementing PQAO.
A3.1.8 Clean Air Status and Trends Network (CASTNET) Lead
The Clean Air Status and Trends Network (CASTNET) Lead is responsible for managing the
monitoring sites organized in the National Park Service (NPS), Clean Air Markets Division
(CAMD), and Bureau of Land Management (BLM) networks. The CASTNET Lead
communicates with the EPA NPAP Regional Leads to assign the monitoring sites within their
respective Region to be audited within the calendar year. The respective NPAP Regional Lead is
then responsible for ensuring the NPAP audits are scheduled and are conducted. The CASTNET
Lead is also responsible for overseeing corrective actions resulting from failed NPAP audits.
\
Contractual
EPA OAQPS
Technical
*¦
*
NPAP Lead
~
v
t4"--
r \
(
\
OAQPS QA
Support
Contractors
EPA Region 4 and
Region 7
Verification
Laboratories
t
EPA Regional
NPAP Leads
CASTNET
Lead
EPA NPAP
Regional
Field Scientists
Self-Implementing
PQAO NPAP Leads
State, Local, and
Tribal
Monitoring
Organizations
y v_
Contractor Field
Scientists
V_
Self-Implementing
PQAO Field Scientists
Figure A3-1. NPAP Communication and Responsibility Structure
A4 Problem Definition/Background
The NPAP is the means by which EPA independently assesses the proficiency of monitoring
agencies to operate National Ambient Air Quality Standards (NAAQS) criteria pollutant gas
monitors that are employed in determining design values for assessing attainment of NAAQS.
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These monitoring agencies comprise several monitoring networks, including: State and Local Air
Monitoring System (SLAMS), Tribal networks, the CASTNET program, Special Purpose
Monitor (SPM) sites, and NPS sites. The NPAP QA audit program is required under Sections 2.4
and 3.1.3 of 40 CFR Part 58, Appendix A. The monitoring data from these networks are of
critical importance in gathering information for making decisions to protect public health. The
monitoring data are necessary to determine if an area is in attainment or non-attainment of the
NAAQS for O3, carbon monoxide (CO), oxides of nitrogen (NO/NOx/NCh), and sulfur dioxide
(SO2), and to assess trends and to model projections of these pollutants. If, in reviewing the data,
an area is found to be in non-attainment status, the responsible state or local monitoring
organization must develop a control strategy in a State Implementation Plan (SIP) to come into
attainment with the NAAQS. Significant funds may be required to come into attainment,
therefore the integrity of the data employed to determine attainment/non-attainment is essential.
The primary purpose of the NPAP is to ensure imprecision and bias of the monitoring data are
acceptably low so that concentrations of criteria pollutant gases reported by monitoring programs
across cities, states, airsheds, regions, and the nation are representative of the actual ambient
concentrations. Secondary goals of the NPAP are to assist monitoring organizations in
identifying and correcting problems and to drive data consistency and comparability across
monitoring sites in the networks.
The NPAP evaluates the bias and variability of criteria pollutant gas monitors via delivery of
PE/audit gas samples to the ambient air monitors. To best evaluate the entire sampling and
analysis system, audit gas samples are delivered to the analyzer TTP, which introduces the
challenge gas directly to the inlet probe, mimicking the sampling and analysis of ambient air.
Providing the test gas to the sample inlet enables evaluation of the entire sampling flow path,
from the sampling station inlet, through the manifold (if so equipped), and to the back of the
analyzer (BOA).
Each EPA Region operates an NPAP TTP program. The TTP audit program in each Region is
either conducted by EPA Region staff or contractors. PQAOs may elect to self-implement the
NPAP program for sites in their PQAO; in such cases independent FS auditors within their
PQAO will conduct the TTP audit program.
For annual PEs, which are conducted by the monitoring agencies, in general, the auditor
generates challenge gas concentrations of the criteria pollutant gases within the ranges agencies
are required to monitor for attainment and related decision-making as required in 40 CFR Part
58, Appendix A, Section 3.1.2.1. The CFR excerpt is below:
3.1.2.1 The evaluation is made by challenging the monitor with audit gas standards of known concentration from at
least three audit levels. One point must be within two to three times the method detection limit of the instruments
within the PQAOs network, the second point will be less than or equal to the 99th percentile of the data at the site or
the network of sites in the PQAO or the next highest audit concentration level. The third point can be around the
primary NAAQS or the highest 3-year concentration at the site or the network of sites in the PQAO. An additional 4th
level is encouraged for those agencies that would like to confirm the monitors' linearity at the higher end of the
operational range. In rare circumstances, there may be sites measuring concentrations above audit level 10. Notify the
appropriate EPA region and the AQS program in order to make accommodations for auditing at levels above level 10.
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Concentration range, ppm
Audit Level
o3
S02
no2
CO
1
0.0040 - 0.0059
0.0003 - 0.0029
0.0003 - 0.0029
0.020 - 0.059
2
0.0060-0.019
0.0030 - 0.0049
0.0030 - 0.0049
0.060-0.199
3
0.020-0.039
0.0050 - 0.0079
0.0050 - 0.0079
0.200 - 0.899
4
0.040 - 0.069
0.0080-0.0199
0.0080 -0.0199
0.900 - 2.999
5
0.070-0.089
0.0200 - 0.0499
0.0200 - 0.0499
3.000 -7.999
6
0.090-0.119
0.0500-0.0999
0.0500 - 0.0999
8.000 - 15.999
7
0.120-0.139
0.1000-0.1499
0.1000 -0.2999
16.000 - 30.999
8
0.140-0.169
0.1500 -0.2599
0.3000 -0.4999
31.000 -39.999
9
0.170-0.189
0.2600 - 0.7999
0.5000 - 0.7999
40.000 - 49.999
10
0.190-0.259
0.8000 - 1.000
0.8000 - 1.000
50.000 - 60.000
To determine NPAP audit levels, EPA compiled national ambient concentrations and averages to
determine appropriate audit levels. Note that with the reduction in measured ambient
concentrations of criteria pollutant gases, monitoring sites are replacing legacy "regular range"
analyzers with instruments capable of "trace level" measurements, which have been widely
adopted across the nation. Specific details for selecting audit levels are further described in
Section B1.1. These updated audit levels have been incorporated into the Performance
Evaluation AQS Tool (PEAT) with which FSs select and conduct NPAP TTP audits.
The mobile NPAP audit laboratories are designed to verify and deliver audit gases TTP to the
inlet of ambient air monitoring stations. Specific and detailed instructions can be found in the
associated NPAP SOPs. A brief summary of the field activities follows:
• The NPAP Regional Lead will select the sites to be audited during the upcoming calendar
year using the AQS audit feature. All sites within a given PQAO are to be audited
minimally every six years.
• One fully trained FS will use NPAP PEAT to help manage and prepare for the audit.
• The FS will verify the operation of the audit gas generation and delivery system.
• The FS will transport/drive the audit laboratory to a pre-selected monitoring station.
• The FS will coordinate the delivery of the audit gas through the station inlet probe, verify
the concentration delivered, and obtain the station reading from the station operator for
each parameter for each challenged audit level.
• The FS will use the PEAT application to record pertinent information during the audit for
measured verification audits (MVAs). If performing a flow-based audit (FBA), the FS will
record the audit information in a hard copy record or electronic log/spreadsheet.
• A draft audit report (typically a hard-copy) will be provided to the station operator, or the
monitoring organization's representative, prior to the FS departure from the monitoring
station. The report recipient will sign the draft audit report or will otherwise document
attesting to the veracity of the site reported concentrations.
• Upon completion of the audit, the FS will use PEAT to upload the audit results to a pre-
production area within AQS (for MVA) or will manually enter the results into AQS (for
FBA).
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• The NPAP Regional Lead (or appropriate designee) is responsible for reviewing the
validity of the NPAP audit using the AQS audit review feature and approving/rejecting the
audit, for which approval will move the audit data into AQS. If no approval/rejection
action is taken, the audit will automatically move into AQS after a pre-determined time
period (7 days for a passing audit and 30 days for a failing audit). If the review and
approval/rejection is not completed prior to the automatic movement of the audit into
AQS, the NPAP Regional Lead (or appropriate designee) is still responsible for reviewing
the validity of the NPAP audit.
• The FS will properly maintain and operate the audit laboratory following manufacturer
recommended procedures for gas analyzers, gas dilution systems, zero-air generators
(ZAGs), on-board electric generators, vehicles, and other equipment as described in the
NPAP TTP SOP.
A5 Project Description and Schedule
The NPAP prescribes audits for the gaseous pollutants for which there are NAAQS, i.e., the
criteria pollutant gases: SO2, NO/NOx/NCh, CO, and O3. The SLAMS are operated by
approximately 170 SLT agencies, all of which are required to be periodically audited in the
NPAP. NPAP audits at each non-excluded regulatory site must be conducted no less frequently
than every six years. These NPAP audits are independent from the PE audit for which each
PQAO is annually required to perform on their monitoring sites as per 40 CFR Part 58,
Appendix A, Section 3.1.2. FSs should attempt to schedule the NPAP audits at least a week
apart, and preferably several months, from the PE audits, if possible, to avoid overlap thereby
increasing the coverage of audits over time.
A5.1 NPAP TTP Description
FSs conduct TTP audits via mobile laboratories, providing gaseous criteria pollutants (O3, CO,
SO2, and NO2) utilizing accurate and reliable resources and instrumentation.
EPA Regional staff, contractors, or self-implementing PQAO auditors (refer to Section A7.1) are
independent of the monitoring organizations that are undergoing the audit and utilize standard
materials and instruments that are likewise independent. Concentrations of the pollutants in the
challenge gas are blind to the monitoring station operators undergoing the audit.
To conduct NPAP TTP audits, auditors utilize mobile laboratories containing a carefully
assembled system of high quality and high capacity (volume/flow) audit gas metering,
generation, and analysis equipment. The mobile laboratories, gas generation systems, and
analyzers have been selected and approved by EPA and are designed to be durable, rugged, and
capable of frequent transport. The concentrations of the delivered challenge gases are metered
and blended from National Institute of Standards and Technology (NIST)-traceable certified
stock gases employing calibrated NIST-traceable equipment. Challenge gas concentrations are
determined by either verification with the independent on-board CO analyzer or ozone analyzer
when performing a MVA or are calculated based on the calibrated generation or dilution of the
standard gas with the gas calibrator when performing a FBA. The MVA is performed unless the
full complement of analyzers cannot be transported to the site, such as for remote sites (e.g.,
those in Alaska and Puerto Rico), in which case the FBA may be substituted.
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For the MVAs, the concentrations of other gases in the blended gas challenge (i.e., SO2 and
NO/NOx/NCh) are calculated based on their known concentration ratios relative to CO. The
generated challenge gas is supplied to the station via a polytetrafluorethylene (PTFE) Teflon®
hose, which directly feeds the inlet probe of the monitoring station. The introduction of the audit
challenge gases into the inlet probe of the monitoring station's sampling system, TTP, is a
critical step in the process such that it takes into account the entire flow path from the inlet to the
station analyzers. Previous versions of this QAPP included discussion of devices that were
shipped to sites and were employed to perform NPAP audits. This "mailed" program involved
shipping audit devices with settings blind to the monitoring station operators such that the station
operator would perform the audit. As each Region now operates or contracts operation of an
NPAP audit system, the EPA no longer performs audits via the "mailed" program; therefore, this
QAPP focuses solely on TTP audit systems.
EPA has recently developed PEAT, a software application that runs on either a laptop computer
or a tablet computer accompanying the FS and audit system to the monitoring site. Briefly, the
PEAT application allows auditors to document the preparation and verification of the audit
equipment and certified standard gases, select sites for audit, schedule audits, identify monitoring
site metadata inconsistencies in AQS, record data generated when conducting audits, perform
calculations, and record the values reported by the monitoring site for the audit. At the
conclusion of an audit, auditors generate a preliminary report for the station operator. Once the
auditor's laptop personal computer or tablet is connected to the internet, the audit results are
automatically pushed to the pre-production area within AQS from which the results are then
entered into the AQS production database.
EPA developed PEAT through the Lean process, which identified several aspects of the NPAP
that were inefficient and/or not performing as required. Starting in March 2016, the previous
spreadsheet workbooks employed for documenting and reporting NPAP TTP audits were retired
and EPA began using PEAT to prepare for, conduct, and report NPAP TTP audits. PEAT has
streamlined the entire NPAP audit process: selection of sites for audit, ensuring monitoring site
details are correct in AQS, evaluating audit performance (calculations), and facilitating input of
NPAP audits to AQS. PEAT has reduced the time required to conduct and report NPAP audits to
AQS and has eliminated many opportunities for errors. This provides monitoring site PQAOs
and EPA Regions with both more reliable audit data and more timely information to better
evaluate and monitor performance of monitoring stations. The previous system utilizing the
spreadsheet workbook required many manual steps and a large investment of staff time to upload
the audit information into AQS. Additionally, audit results for monitoring sites for which there
were discrepancies in the site information (particularly method codes) were rejected for input
into AQS. Auditors, Regional NPAP Leads, and the OAQPS NPAP Lead were required to
maintain audit data in databases and perform quality control (QC) checks to ensure the audit data
were of acceptable quality to upload to AQS. The PEAT process has been designed to combine
many of these steps to minimize data handling and to minimize or eliminate those discrepancies
and barriers to promote regular and timely entry of audit data into AQS.
EPA OAQPS in RTP, NC is responsible for updating the PEAT and ensuring that it is current for
auditors to utilize. EPA encourages auditors to report problems, comments, or suggestions to
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OAQPS in order to improve the functionality of PEAT. Enhancements and updates to PEAT are
pushed periodically to users' computers to ensure the most recent version of PEAT is available.
Unless FSs are EPA employees, FSs do not have direct access to AQS, rather the interactions
with AQS occur through PEAT. As such, it is critical that auditors are using the most current
version of PEAT. PEAT utilizes prompts when the user logs into the application to ensure that
only the most current version of the application is available. When the auditor has completed
entry of information into PEAT and has completed an audit, the audit result data transfer to AQS
is handled within PEAT. The auditor must archive the data acquisition system (DAS) data to
ensure that both the mobile laboratory temperature and DAS instrument traces from the CO and
ozone analyzers are maintained. The data from the DAS are not handled within PEAT and must
be archived separately.
A5.2 NPAP Site Selection and Schedule
Each non-excluded regulatory (eligible) monitoring site within each PQAO of each EPA Region
is to be audited minimally every six years. These eligible sites include all monitoring sites that
are not marked in AQS with a NAAQS exclusion code, i.e., their monitors are non-regulatory.
Each calendar year, at least 20% of the eligible monitoring sites within each PQAO are selected
for audit such that 100% of the monitoring sites within the PQAO (and therefore within the
Region) are audited within the six-year period. Following the 20% requirement, all sites could be
covered in a five-year period, but the six-year period allows for sites with special interest to be
audited as needed during the six-year period.
A5.2.1 Site Selection
Audit selection is performed at the Regional level. EPA Regional NPAP Leads may select the
sites to be audited in the coming calendar year, may delegate selection of the year's audits to the
auditor(s) or PQAO NPAP Lead, or may work closely with the auditor(s) to select the sites for
the year's audits. Regardless of the convention chosen for selecting sites, the EPA Regional
NPAP Lead must approve the list of selected sites for audit.
During the autumn of each year, the Regional NPAP Leads and/or FSs generate the list of
candidate sites to be audited in the next calendar year in their Region within AQS via the AQS
audit feature. Site lists generated in AQS include the most recent date of audit such that auditors
can sort the list of eligible monitoring sites by most recent audit date. Any site that does not have
a NAAQS exclusion code in AQS and is designated as "regulatory" will be included in the list
generated, and can be selected for an audit. For each Region, 20% of the sites in each PQAO are
to be audited annually, with the stipulation that all sites within the PQAO are to be audited
within a six-year period. The AQS audit feature permits sorting and filtering by PQAO and
includes a feature to calculate the number of sites required to be audited (> 20% of the total in
the PQAO). If a monitoring organization has not been audited for a pollutant for four years, an
audit for that monitoring organization should be prioritized. Priority should also be given to sites
that report measured concentrations near the NAAQS, sites in non-attainment areas, and sites for
which PE audits conducted by PQAOs are found to exceed the PQAO's own acceptance limits.
Repeat audits for sites failing TTP audits can be scheduled as resources permit. Note that audits
of CASTNET sites are in addition to, and not included in, the annually required 20% of sites
within a PQAO.
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Once the list of candidate sites is finalized and approved by the Regional NPAP Lead, the list is
distributed to the OAQPS NPAP Lead and to the FSs. OAQPS annually withholds appropriate
amounts of state and tribal assistance grants (STAG) 105 funds based on this list; therefore, the
audit selection list must be completed and submitted to the OAQPS NPAP Lead by October 1 of
the preceding year to ensure funding deadlines are met.
The Regional NPAP Lead or FS then generates a site validation report within AQS for each
parameter to be audited for each site selected for audit. These site validation reports include the
site metadata specific to each parameter subject to audit, including:
• AQS identification (ID)
• site name
• address
• latitude and longitude
• date site established
• site owner
• monitor ID including parameter measured and dates of last data collection and data
upload to AQS
• agency contact information
• PQAO
• probe height
• parameter method and associated instrument manufacturer, model, and associated
comments.
These site validation reports are provided to FSs and to the PQAO monitoring organization
managers to verify the information. Monitoring organization managers are responsible for
updating outdated or incorrect information within AQS before the audit. Regional NPAP Leads
should contact the monitoring organization managers within two weeks of distributing the site
validation reports to ensure needed changes have been made in AQS. Before each audit, PEAT
polls the current site information from AQS, therefore, it is imperative that the information be
correct and current. If the information is not correct, the auditor may experience difficulty
uploading the audit results to AQS.
A5.2.2 NPAP Equipment Preparation Schedule
Auditors must assemble the necessary materials and equipment and ensure that standard
materials (gases and ozone generators) are verified and devices (gas blending calibrator, gas
analyzers, ZAGs, and data loggers) are calibrated and operating properly. These verifications
must be performed sufficiently in advance (recommended to be minimally one month) of
beginning of a year's audits to ensure corrective actions (replacing parts, components,
recalibration, etc.) can be taken before scheduled audit dates. Note: Several of these calibrations
or calibration verifications must be performed quarterly (consult Table A6-1).
Specifically, the following verification steps must be completed prior to conducting NPAP TTP
audits:
• O3 line loss test
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• O3 standard generator calibrated against a Level 1 (standard reference photometer [SRP])
or Level 2 ozone standard
• O3 analyzer (Level 2 ozone standard) calibration verification
• CO cylinders concentration verification: Low CO and High CO (for MVAs)
• Multiblend cylinder concentration verification for NO, SO2, and CO
The specific QC guidelines are located in Section A6.
A5.2.3 TTP Audit Scheduling
FSs, separately or in concert with the EPA Regional NPAP Lead (and PQAO NPAP Lead, as
appropriate), shall develop an audit schedule based on the list of sites selected to be audited in
the coming calendar year. Development of the schedule should include consideration of
conducting technical systems audits (TSAs) and/or Performance Evaluation Program (PEP)
audits concurrently with the NPAP audits. These considerations are discussed below:
TSAs: Conducting TSAs of the monitoring sites concurrently with an NPAP audit may
be time and resource efficient, particularly for the EPA Regions that conduct their own
NPAP TTP audits (in lieu of having a contractor audit team). For EPA Regions that rely
on contractors to conduct NPAP TTP audits, a concurrent TSA may still be time and
resource efficient. Per 40 CFR Part 58, Appendix A, Section 2.5, TSAs are required to be
conducted every three years for each PQAO unless the PQAO consists of more than one
monitoring agency, in which case, each monitoring agency must be subject to a TSA
every six years such that all monitoring agencies within the PQAO are audited within six
years. TSAs are outside the scope of the NPAP and will not be further discussed within
this QAPP.
PEP for PM2.5 and Lead (Pb): In addition to NPAP TTP audits, EPA Regional and
contractor FSs typically conduct audits for the EPA PEP for particulate matter with a
diameter less than or equal to 2.5 micrometers (PM2.5) and Pb at monitoring sites that are
required to monitor for the NAAQS. EPA Regional Leads and FSs may consider the need
to conduct these PEP audits concurrently, at the same or nearby site, when planning
NPAP audits.
The final audit schedule is to be approved by the EPA Regional NPAP Lead. Once the audit
schedule has been approved by the Regional NPAP Lead, auditors should contact the sites
chosen for the audits to fine tune adjustments to the schedule, as practical. Changes in the
schedule are to be communicated to the Regional NPAP Lead.
A5.2.4 Pre-Audit Communication Schedule
The FS and/or Regional NPAP Lead shall contact the monitoring site operator minimally one
month prior to the audit and again approximately one week prior to the scheduled audit date to
confirm the audit. These communications should include discussion of connections to the site
instruments, electrical power needs (if any), logistical concerns, procedures and roles for the
audit, equipment or site changes, and personnel expected to be present during the audit. It is
helpful to exchange cellular phone numbers and email addresses to ensure problems or issues
with arrival at the monitoring site are properly communicated. If problems arise, monitoring site
operators should be contacted as soon as possible.
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A5.2.5 Schedule for Audit Reporting to AQS
Audit results are to be submitted to AQS within 3 months of the audit. In practice, audit data are
routinely submitted to AQS within less than three months as PEAT incorporates automatic
submission of audit data to the pre-production area within AQS. Depending on whether the audit
evaluation was acceptable or unacceptable, data are subsequently automatically submitted to the
production database within AQS within 7 days or 30 days, respectively, after the data are
uploaded to the pre-production database. Regional NPAP Leads are to review and validate the
audit data while the audits are in the AQS pre-production environment. Regional NPAP Lead
approval of an audit during these timeframes will move the audit to the production database
within AQS. If the Regional NPAP Leads do not review, validate, and approve the audit within
the required timeframe, the audit will automatically move to AQS.
A5.3 Field Scientist Responsibilities
The EPA Regional, contractor, or PQAO FS shall prepare and calibrate the audit systems as
described below and in the NPAP TTP SOP.
The auditor(s) will acquire the necessary equipment and materials for conducting the audit as
described in the NPAP TTP SOP. Standard gases must be NIST-traceable and within the
certification expiration. Equipment for generating and blending challenge gases must be
demonstrated to be in proper operable condition and calibrated per the NPAP TTP SOP.
The auditor shall prepare/calibrate the audit systems/materials according to the NPAP TTP SOP.
The auditor shall check each audit system, component device, and standard for cleanliness,
operational fitness and calibration, as appropriate, prior to use in the NPAP, and shall
document/record in PEAT the date these checks/verifications were performed.
The auditor shall ensure that standard gases that have been previously purchased and certified,
and of which sufficient quantity remains to appropriately conduct audits, are verified minimally
every 12 months. Verification may be performed by the verification laboratories in EPA Regions
4 and 7, by the gas vendor, or by a certified gas analysis laboratory compliant with EPA's
Ambient Air Protocol Gas Verification Program (AA-PGVP).
A6 Quality Objectives and Criteria for Measurement
The primary objective of the NPAP is to assess the bias and imprecision of the measured ambient
concentrations of criteria pollutant gases reported by monitoring sites. To meet this objective, the
quality objectives and criteria for the NPAP relate to:
• characterizing the bias of the audit materials and devices utilized in generating audit
gases, and
• the completeness of the audits scheduled for a given calendar year.
These objectives and criteria must be met in order to properly assess the bias of concentrations of
criteria gases reported by the audited monitoring sites.
The PEAT application is designed to guide the auditor through the NPAP process and to provide
status reports and warnings. PEAT is constructed of modules that guide the auditor in completing
specific tasks and in recording associated information within PEAT prior to conducting an NPAP
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audit with PEAT. For example, auditors must have completed calibration and certification of
standard materials or equipment and recorded these via the "Prepare and Certify Equipment"
module in PEAT before the "Audit Tasks" module within PEAT is enabled, which permits the
auditor to schedule and conduct audits within PEAT.
A6.1 Audit Devices and Materials
Devices and materials utilized in generating, metering, or measuring standard gases are to be
certified or its bias determined against a NIST-traceable standard or device prior to use unless
such is not available or applicable. For such components for which there is no traceable standard
(e.g., the TTP gas delivery line), the performance (bias) of the component must be characterized
by measurement with an instrument calibrated against a NIST-traceable standard. Each device
and material has a prescribed certification timeframe during which the device or material may be
utilized, after which the device or material will require verification, redetermination of the bias,
or replacement with a comparable device or material such that only devices or materials that are
within their certification period are employed for conducting NPAP audits. These timeframes are
specified in Table A6-1.
Audit devices include gas dilution blending calibrators with an ozone generator, zero (acceptably
pollutant-free) air generators, and gas analyzers (CO analyzer and ozone photometer). The NPAP
TTP SOP describes the calibration (standardization and verification of calibration) of
instruments, devices, and the analysis of performance audit/proficiency test samples as well as
performance specifications for each device or material.
Section 9 of 40 CFR Part 58, Appendix E stipulates that all materials in contact with reactive
gases (SO2, NO2, and O3) must be non-reactive. Such materials include fluorinated ethylene
propylene (FEP) or PTFE Teflon® and borosilicate glass. Contact of these gases with stainless
steel should be minimized as even chromatographic grade (e.g., 316 stainless or silicon-ceramic
lined stainless steel) can have surface defects or active sites that serve as destructive catalysts for
these gases.
Table A6-1. Certification and Verification Specifications for Audit Devices and Materia s
l)i-\ iiv or
M.iU-rhil
(Vrlilkiiliiin or
ViTilUuliiin l-'iV(|iK'iu\
( i'iiilli;ilion or YiTirk;ilion
Sl;i iul;i rd
Spi'i ilKill ion
Multiblend
certified gas
cylinder (CO, NO,
and SO2)
Veriiication not to exceed
12 months
Against first generation NIST
standard gases by gas manufacturer
or verification labs in Regions 4 or
7, or other certified gas analysis
laboratory compliant with EPA
AA-PGVP
Within ±3% of the original
certified concentration
from manufacturer and
within ±2% of the
previous verification value
High CO gas
cylinder
(3.5 - 6.5 parts per
million [ppm])
Verification not to exceed
12 months
Against first generation NIST
standard gases by gas manufacturer
or verification labs in Regions 4 or
7, or other certified gas analysis
laboratory compliant with EPA
AA-PGVP
Within ±3% of the original
certified concentration
from manufacturer and
within ±2% of the
previous verification value
Low CO gas
cylinder
(0.3 - 1.2 ppm)
Verification not to exceed
12 months
Against first generation NIST
standard gases by gas manufacturer
or verification labs in Regions 4 or
7, in RTP, or other certified gas
analysis laboratory compliant with
EPA AA-PGVP
Within ±3% of the original
certified concentration
from manufacturer and
within ±2% of the
previous verification value
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Table A6-1. Certification and Verification Specifications for Audit Devices and
Materials (continued)
l)e\ iiv or
Mali-rial
Cerl ilka lion or
Yerilkalion l-'iV(|iK'iu\
(Vrlilkalion or Yerilkalion
Standard
Speiiliialion
Ultra-pure zero air
(high pressure
cylinder)
Expiration or retest date
not specified
Examination of certificate of
analysis (COA)
COA must show: total
hydrocarbons (THC) <
0.01 ppm, CO <0.01 ppm,
oxides of nitrogen <0.001
ppm, and SO2 < 0.001
ppm
ZAG output
Performance verified with
each audit performed
Compared to the zero air source
scrubbed by an external palladium
scrubber or to ultra-pure zero air
from a high-pressure cylinder
CO response in the zero
air from the ZAG must not
be > 0.02 ppm greater than
the ultra-pure zero air or
zero air scrubbed through
an external palladium
scrubber
Ozone primary
standard (Level 2
ozone standard)
Calibration established or
verified within the
previous three months
Against a Level 1 ozone standard
(SRP)
Within ±3%) of slope and
within ±3 parts per billion
(ppb) of the intercept of
the SRP
CO analyzer
Calibration established
each day of use for TTP
audits
Calibration verified prior
to and immediately
following each audit
Calibration established with High
CO gas cylinder and zero air
Calibration verified against the
Low CO gas cylinder
Calibration verification
against Low CO must be
within ±3%) of Low CO
certified concentration
Calibrator: gas
dilution system,
gas phase titrator,
and ozone
generator
Ozone generator
calibration established or
verified quarterly
Against a Level 1 (SRP) or Level 2
ozone standard
Within ±5%) of the
selected standard at each
concentration representing
Levels 2 through 6
Mass flow controller
(MFC) calibration
established (adjusted)
within the previous three
months and verified
immediately after
calibration and the day of
each audit (strongly
recommended).
Note: this is required for
performing flow-based
audits.
Against a certified reference flow
transfer standard
Calibration is performed at 10 flow
rates spanning 10 to 90% of the
flow rate range
Verification is performed at 3 flow
rates spanning 10 to 90% of the
flow rate range
Calibration verification
must show indicated flow
rate is within ±2% of the
flow transfer standard
reading for each tested
flow rate
Flow transfer
standard
Annually by a qualified
NIST-traceable metrology
laboratory
Calibration verified or established
against a NIST-traceably certified
flow standard
Within ±1% of the NIST-
traceably certified
standard across the flow
range
Ozone line loss
test
Quarterly challenge the
following concentration
points: 0.200,0.125,
0.050, and 0.010 ppm
Ozone evaluated upstream of and
from effluent of PTFE delivery line
Ozone loss at each
concentration level must
be <2.5 ppb
Environmental
conditions
temperature probe
Temperature probe
calibration verified within
the previous 12 months
Readings verified against a NIST-
traceably certified thermometer at
minimally one temperature
between 20 to 30°C
Within ±2°C of the
certified thermometer
reading(s). If outside this
criterion, adjust probe
response to match certified
thermometer
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A6.2 Bias of Audit Stock Standard Gases
Stock standard gases employed by auditors for generating challenge gases and for
verifying instrument calibration for measuring/confirming challenge gas concentrations
in conducting NPAP audits must have been certified or the concentration verified within
the previous 12 months. Such verification demonstrates that the concentration of standard
gases from which challenge gases are diluted are demonstrated to be within ±3% of the
originally certified value and within ±2% of the most recent verified concentration by
comparison to a first generation NIST-certified standard.
Since O3 cannot be maintained in a cylinder, it must be generated when needed by an
ozone generator. Ozone generators integrated into the gas phase titration (GPT)
calibrators are to be calibrated (calibration established or verified) quarterly against an
SRP (Level 1 standard) or recently certified Level 2 standard, such as an NPAP ozone
analyzer. The ozone generator calibration must be within ±5% of the standard at
representative concentrations in audit Levels 2 through 6. Level 2 ozone analyzer
standards are typically calibrated against the SRP owned by the EPA Region. If the
Region does not operate an SRP, the Level 2 ozone standard calibration for such Regions
can be performed by a Region operating an SRP.
A6.3 Confirming Challenge Gas Concentrations
It is strongly recommended that, for MVAs, the MFCs within the GPT gas dilution
calibrators employed for diluting gases for conducting NPAP audits be calibrated (the
calibration established) in the previous three months and the calibration verified on the
day of each conducted audit.
NOTE: When performing FBAs, the MFCs in the gas dilution calibrator must
have been calibrated in the previous three months and verified each day of audit
conduct.
The MFC calibration verification lessens the likelihood of a gross error in preparing
dilutions of the stock standard gases; however, it does not account for deviations in
challenge gas concentration from the expected theoretical nominal concentration due to
leaks, reactions, or contamination within the gas generation and dilution system. As a
result, for MVAs, challenge gas concentrations are verified through analysis by gas
analyzers calibrated against NIST-traceable certified standards. The calibration of the CO
analyzer is established with each multiblend MVA and the Low CO standard is analyzed
immediately following the calibration to verify the calibration. The ozone analyzer
calibration must have been established or verified within the past three months and
verifications must show the response to be within ±3% of the certified Level 1 standard
(SRP) and the intercept of the linear regression within ±3 ppb. Additionally, losses of
ozone through the delivery line are characterized quarterly as described in Table A6-1
and in the NPAP TTP SOP and this bias incorporated in the determination of the ozone
challenge concentrations measured with the ozone analyzer.
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A6.4 Completeness
The data completeness measurement quality objectives for the NPAP are to conduct an
NPAP audit at all NAAQS monitoring sites over a six-year period, conduct audits at 20%
of the sites in each PQAO annually, have > 95% of all NPAP audits scheduled for the
calendar year completed, and report all audit results to AQS within three months from
completion of the audit.
A6.5 Characterizing Monitoring Station Bias
Monitoring sites must meet the acceptance criteria specified in Table A6-2 for the criteria
pollutant gases for each provided audit challenge concentration (level). The comparison
is completed by using the measurement reported by the site and the certified challenge
gas concentrations measured by the FS and determining either a percent difference or
concentration difference. The percent difference is calculated per the following formula:
% difference = (station reported concentration - challenge concentration) x 100
challenge concentration
The concentration difference is calculated by subtracting the challenge concentration
from the station reported concentration.
If the specified criteria listed in Table A6-2 are not met for any audit level of 3 through
10, the audit is deemed unacceptable (failed) and the PQAO/monitoring site must take
corrective action to rectify the problem. The Regional NPAP Lead will coordinate with
the audited agency's QA group to address the problem and demonstrate that it has been
resolved. At the discretion of the Regional NPAP Lead, a re-audit may be scheduled if
time and funding allow; however, there is no requirement for a re-audit.
Table A6-2. Acceptance Criteria for NPAP TTP Audits
Audit
Parameter
Audit
Levels
Acceptance Criteria
S02
1 and 2
±1.5 ppb or ± 15%, whichever is greater, of the challenge gas
concentration at each level
3 through 10
± 15% of the challenge gas concentration at each level
no2
1 and 2
±1.5 ppb or ± 15%, whichever is greater, of the challenge gas
concentration at each level
3 through 10
± 15% of the challenge gas concentration at each level
o3
1 and 2
±1.5 ppb or ± 10%, whichever is greater, of the challenge gas
concentration at each level
3 through 10
± 10% of the challenge gas concentration at each level
CO
1 through 10
± 15% of the challenge gas concentration at each level
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Note that, although auditors may observe obvious problems with configuration,
housekeeping, or other aspects that may impact the ability to report acceptable results,
under no circumstances should an auditor suggest or allow alteration to the monitoring
site prior to or during performance of the audit. The audit must be performed on the site
in an "as-is" condition and the auditor may not allow the station operator to make
changes to the audited system until the audit is complete. Auditors who are contractors
may not perform troubleshooting or aid in corrective action at the audited site during the
process of or following an audit unless specifically authorized to do so by the Regional
NPAP Lead. Independent PQAO auditors may offer corrective technical assistance in
keeping with their governing QAPP and/or policies.
If corrective action is authorized, typical post-audit troubleshooting may involve
inspection of the intake manifold or disconnecting the station analyzer from the inlet and
performing an audit through the BOA. If the problem is resolved before the EPA auditor
has left the site, the auditor may be granted the authorization by the Regional NPAP Lead
or PQAO NPAP Lead to conduct a repeat audit on the same day or may schedule a repeat
audit at a later date per direction of the Regional NPAP Lead or PQAO NPAP Lead.
A7 Training Requirements and Certification
FSs, whether EPA employees, contractors, or PQAO staff, must be properly trained and
certified to conduct TTP audits. Formal training is required for new personnel and is
typically conducted at the EPA Headquarters office in RTP, North Carolina, the EPA
Regional offices, or at another appropriate site. The trainer must hold a current training
certification to conduct NPAP audits and have been involved in conducting at least 10
NPAP audits in the last three years.
This initial FS training will include a hands-on practical and a written examination.
Following the initial certification, new auditors must work with an experienced auditor to
conduct at least four separate audits at four separate monitoring sites to learn the
processes and procedures for operating the equipment. Of these four audits, two must be
ozone and two must be blended gas audits. In some cases, four audits may not be
sufficient, and the trainee may need more time conducting audits. The Regional NPAP
Lead or OAQPS NPAP Lead must approve the initial training and readiness before new
auditors can conduct NPAP audits independently. Once an auditor is approved to conduct
audits independently, recertification is required annually thereafter.
Each calendar year, as time and resources allow, an annual recertification course will be
offered by the EPA Headquarters office in RTP, North Carolina. All FSs are required and
Regional NPAP Leads are encouraged to attend these training sessions, which include a
combination of classroom lecture and hands-on instruction, followed by a written
examination. Trainees will attend lectures/demonstrations of experienced auditors and
will work directly with auditing equipment under the supervision of experienced trained
auditors, as practical. New and experienced auditors must demonstrate proficiency with
operating audit equipment and achieve a passing score (> 90%) on a written exam to
receive initial or ongoing certification. These formal training sessions provide an
opportunity for auditing staff from the various Regions/PQAOs to share their knowledge
and present real-world experiences. Individuals new to conducting audits are introduced
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to experienced auditors and have opportunities to ask questions and network with
experienced staff. When resources do not permit auditor travel to RTP, efforts will be
made to re-certify and train staff at other Regions or through webinars.
Other training opportunities are provided as resources allow and may include training
sessions held at Regional offices for smaller groups or conducted as webinars for
classroom instruction. Auditors are encouraged to take advantage of and participate in as
many of the training sessions as possible.
A7.1 Self-Implementing PQAOs
PQAOs wishing to implement their own TTP audit programs may do so and must comply
with the requirements listed in Section 3.1.3.4 of 40 CFR Part 58, Appendix A, the NPAP
Program Adequacy/Independence Criteria Memo (July 2008 - available at
https://www.epa.gov/sites/production/files/2020-
1O/documents/npapadeq uacv072408.pdf). and the National Performance Audit Program,
PM2.5, PM10-2.5, and Lead PEP Implementation Decision Memorandum prepared each
calendar year. Few agencies have elected to operate their own NPAP TTP program since
the personnel and equipment resources required to operate an independent NPAP TTP are
significant. Such agencies have been provided with guidance and independent
certification support.
The following criteria listed in 40 CFR Part 58, Appendix A, Section 3.1.3.4 must be met
for self-implementing PQAOs:
1. PQAO audit systems and personnel must be separate from the audit system
employed to conduct the annual PQAO internal TTP PE audit and must be
equivalent to a federal EPA NPAP audit system.
2. The PQAO audit system must be checked (verified) annually against an
independent EPA-certified laboratory, or equivalent.
3. The PQAO audit system must conduct a collocated audit with an EPA-certified
NPAP audit system annually:
a. One collocated audit is required for agency networks with < 5 sites
b. Two collocated audits are required for agency networks with > 5 sites
4. The NPAP must be incorporated into the PQAO criteria monitoring QAPP.
5. The audit system and data generated must be subject to review by qualified
independent EPA personnel.
6. PQAO FSs must participate in initial and ongoing training and certifications.
A memo describing the requirements and associated costs for self-implementation,
National Performance Audit Program, PM2.5, PM 10-2.5, and Lead Performance
Evaluation Program Implementation Decision Memorandum, has been developed for
agencies seeking self-implementation to better define the requirements in CFR. This
memo is to be updated annually and covers the subsequent calendar year. The annual
memo can be acquired by contacting the OAQPS NPAP Lead. The 2017 annual memo is
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available at the following URL:
https://www3.epa.gov/ttn/amtic/files/ambient/pm25/qa/Final%202017 07-27-074109.pdf
For agencies that elect to operate their own program, the program must be approved by
EPA. As cited in 40 CFR Part 58, Appendix A, Section 3.1.3.5, "OAQPS, in consultation
with the relevant EPA Regional Office, may approve the PQAO's plan to self-implement
NPAP if the OAQPS determines that the PQAO's self-implementation plan is equivalent
to the federal programs and adequate to meet the objectives of national consistency and
data quality." Approval of the program is necessary to ensure that the PQAO TTP audit
data are equivalent to the data obtained by a Regional or contractor TTP auditor. The
approval process includes a side-by-side performance audit at one or more sites by both
the PQAO and Regional or contractor TTP auditors and TTP systems. Critical elements
of the comparison audit are then reviewed to ensure the results are essentially equivalent
such that the difference between the two sets of results are within ±5% for each
concentration point for ozone and within ±7% for each concentration point for SO2, CO,
and NO2, as specified in the most recent annual adequacy memo. EPA may also conduct
TSAs of the PQAO FSs, audit systems, and audit documentation records to ensure the
NPAP TTP audits conducted by the PQAO meet the necessary requirements and are
conducted equivalently to the EPA's NPAP program.
A8 Documentation and Records
A8.1 Equipment and Standards Certification Records
Records are to be kept on acceptance testing of audit materials and calibration of audit
devices. These records allow the tracking of an audit material/device from its initial
acceptance through to the storage of the audit results in AQS. Certification and
calibration records for devices and materials utilized in NPAP are maintained by the
auditor or cognizant Regional office for minimally one year after which they are
transferred to EPA OAQPS where they are maintained until archived by EPA. These
records can be hard copy printouts or electronic files such as pdfs. Each Regional office
must have a designated area where these records are appropriately stored.
Self-implementing PQAOs will maintain and archive records required to reconstruct
acceptance testing, calibration, and verification of audit materials and devices according
to their governing QAPP, which will comply with the cognizant EPA Region
requirements.
EPA AA-PGVP certification laboratories perform verification, certification, and
calibration of devices and materials and must maintain documentation and records for
these activities. The AA-PGVP certification laboratories are to archive calibration
documentation and records per the 2010 QAPP for the AA-PGVP.
A8.2 Challenge Gas Generation and Verification Records
Records of instrument outputs (e.g., output from dataloggers) for verifying challenge gas
concentrations and demonstrating stability as well as logged instrument environmental
temperature data must be maintained. Outputs from dataloggers or DAS within which
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auditors annotate the demonstration of challenge gas stability or assignment of challenge
gas concentration must be likewise maintained in order to reconstruct audit activities.
These records, whether electronic and/or hard copy, are to be maintained by the auditor
for minimally three years after which they are transferred to the Region where they are
maintained until archived by EPA OAQPS.
A8.3 PEAT Records
The PEAT application requires auditors to have username and password credentials for
accessing the system. The username and password are unique to the individual and are
not shared with other individuals. All data recorded within PEAT are attributable to an
individual user, and date and time are recorded for all entries, maintaining the
identification of each individual associated with each record. PEAT is an application
which polls and writes data to the AQS database. PEAT also stores analyzer calibration
data and dates, certified audit gas concentrations and expiration dates, and other quality
control records for the audits; however, this information is not transmitted to AQS. PEAT
maintains this calibration and certification information within the tablet or laptop PC
memory for the convenience of the auditor such that PEAT pre-populates the audit form
and the auditor does not need to enter the information for each audit. Since this
supplemental information only resides in the PEAT application, the auditor must use the
backup function in PEAT to make a copy of the database and store it in a secure location
following each audit trip.
The current version of the PEAT application and all previous versions are maintained on
a server at EPA's RTP location. Maintenance, redundancy, and access control to the
PEAT application files comply with EPA information technology (IT) policies and
procedures and will not be addressed within this QAPP.
A8.4 Audit Results Report
Once the audit is completed and prior to the auditor departing the audited monitoring site,
the auditor provides the draft audit report to the station operator or monitoring agency
representative who documents receipt and attests to the veracity of the site reported
measurements in the report. This will typically be accomplished by the FS printing two
copies of the audit report, which are then signed by both the auditor and the station
operator or monitoring agency representative. The FS maintains one copy and the other
remains with the audited monitoring site staff. However, the FS may also electronically
transfer the audit report (e.g., via e-mail) and the site operator or monitoring agency
representative can respond indicating concurrence.
The audit report is generated within PEAT (for MVAs) and details the results of the
audit, indicating the challenge concentrations for each parameter, the concentrations
reported by the site, the percent differences or concentration differences for each criteria
gas at each challenge concentration, and whether the results were acceptable (passing) or
indicated failure. Once the report is generated within PEAT the FS cannot edit the audit
data. If there were problems or issues that impact the validity of the audit conducted, the
FS will contact the Regional NPAP Lead so the audit can be marked invalid within AQS.
Audit reports for FB As cannot be prepared within PEAT and will be prepared within the
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spreadsheet workbook for distribution to the monitoring site staff (which may be hard
copy or electronic).
Once the audit report has been generated for MVAs, the data are stored electronically
within the tablet or laptop computer and staged for posting to the pre-production area
within AQS. When the laptop or tablet computer is connected to the internet, PEAT will
automatically upload the audit data to the pre-production area within AQS. FSs must
manually upload FBA audit results to AQS; typically this is accomplished by functions
within the spreadsheet workbook that generate an-AQS ready transaction file for
uploading.
For evaluations that were acceptable (passing) for the challenged criteria pollutant gas
concentrations, the auditor need take no further action and the audit results will be
uploaded from the pre-production area in AQS to the production database in AQS
automatically within seven days, provided the NPAP Regional Lead has not validated
and approved the audit (in which case it would be uploaded immediately following
approval). Audits for which there were failures for any of the concentration levels of the
challenged gases are staged in the pre-production area within AQS for 30 days after
which they are loaded to production database within AQS, provided that the NPAP
Regional Lead has not invalidated (rejected) or validated and approved the audit. This 30-
day period permits review of the audit data by the FS, EPA Regional Lead, and
monitoring organization manager and permits changes to be made to the audit record, if
such are deemed appropriate, prior to the audit record upload to the AQS production
database. Once uploaded to the AQS production database, the audit is locked and cannot
be altered.
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B. MEASUREMENT/DATA ACQUISITION
B1 Sampling Process Design - Concentration Selection, Generation,
Verification, and Delivery of Challenge Gases
The objective of the design of the NPAP TTP process is to ensure that generated
challenge gas concentrations are stable, accurate, and representative of sampled air
analyzed by criteria pollutant gaseous monitoring stations. This objective drives the
equipment chosen and procedures developed for the TTP audit program. Gases and
devices employed in the generation and delivery of the challenge gas are of a known high
quality as demonstrated by comparison to NIST standards. The auditor has the
responsibility of ensuring that the materials and devices are appropriately certified,
calibrated, and/or characterized and within the certification date as specified in Table
A6-1.
The equipment for generating, verifying, and delivering the audit challenge gases are
transported to the audit sites in one of three mobile configurations:
• a case-based system with the audit equipment mounted within racks, is
transported to the site in an enclosed truck or van, and may be moved by attached
wheels or a hand truck;
• a large self-contained van/enclosed truck in which the instruments are
permanently installed,
• or a vehicle with a tow-behind trailer in which the equipment is permanently
installed.
Audit equipment includes gas blending instruments, ZAGs, ozone generation
instruments, and analysis instruments to verify challenge gas concentrations. Audit
materials include NIST-traceable certified stock standard gases for generating blended
challenge gases and NIST-traceable certified calibration gases to calibrate gas analyzers
with which challenge gas concentrations may be verified.
There are four or five main steps to conducting the NPAP TTP audit: selecting challenge
gas concentrations, generating the challenge gas, verifying the concentration of the
challenge gas through independent measurement (note the concentrations are not
confirmed by independent analysis when performing FBAs), delivering the verified
concentration challenge gas to the monitoring station undergoing audit, and recording the
reported concentrations measured by the monitoring station.
Bl.l Selecting Challenge Gas Concentrations
For MVAs, the auditor measures concentrations of the generated challenge gas with
instruments, independent from the gas generation system, calibrated against NIST-
traceable certified standards to ensure that the challenge gas concentrations delivered to
the monitoring station inlet for analysis are accurate with respect to the intended
concentrations. For FBAs, the concentrations of the challenge gas are not independently
verified by analysis and are determined by the calibrated dilution of the standard
multiblend gas or calibrated generation of ozone. Generated concentrations of ozone are
corrected for demonstrated loss through the delivery line for both MVAs and FBAs. The
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delivery of the challenge gas to the monitoring station is complicated by the fact that
several of the gases employed in the generation or delivered to the monitoring station are
reactive and prone to losses before they can be measured by the station analyzer. For this
reason, procedures have been established for warm up and conditioning of the
instruments and gas transfer and delivery lines before the challenge gas can be measured
by the monitoring station. Specific procedures for instrument warm up and conditioning
are detailed within the NPAP TTP SOP.
When conducting an NPAP audit, the auditor provides minimally four different
concentration levels of each required criteria pollutant gas to the station. The
concentration range of the selected levels must cover the 99th percentile concentration of
ambient concentrations reported by the site for each of the required criteria pollutant
gases; thus, the selected concentrations will vary by audited site. EPA OAQPS has
reviewed the ambient measured concentrations of the criteria pollutant gases and has
determined that this 99th percentile concentration criterion is met by auditing
concentrations in Levels 2, 3, 4, and 5 for each pollutant gas. EPA has effectively
eliminated the need to have different audit levels needed for monitoring sites operating
different equipment; e.g., "full scale "or "trace level" instruments.
FSs (whether EPA Regional staff, contractors, or self-implementing PQAO auditors) are
to minimally select concentrations within Levels 2, 3, 4, and 5 for each of the pollutant
gases to be audited at each monitoring site undergoing audit. If time and monitoring site
instrument sensitivity allow, the FS should audit at a concentration in Level 1 as well.
The monitoring stations are formally evaluated for pass/fail on their measured
concentrations for gas concentrations provided in Levels 3, 4, and 5 (highlighted yellow
in Table Bl-1) and additionally for any audit including concentrations in Levels 6
through 10. Audit concentrations in Levels 1 and 2 (highlighted pink in Table Bl-1) are
being collected to evaluate bias at these "trace" levels. Monitoring site pass/fail is not
evaluated on the results of the Levels 1 and 2 measurements in PEAT or AQS; however,
NPAP Regional Leads may prescribe that monitoring sites need to meet the Levels 1 and
2 acceptance criteria to successfully pass the audit.
The audited concentrations in Levels 3, 4, and 5 represent typical national ambient air
concentrations for the criteria pollutant gases. NPAP TTP audits will not typically
involve challenging monitoring stations at concentrations above Level 5; however, FSs
may provide additional audit points in Levels 6 through 10 if the monitoring site
measures ambient concentrations of pollutant gases commensurate with these Levels (as
may be the case for SPM or industrial monitoring sites).
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Table Bl-1. Expanded NPAP Audit Levels and Associated Concentrations
ppm
Audit Level
03
S02
N02
CO
1
0.0040 - 0.0059
0.0003 - 0.0029
0.0003 - 0.0029
0.020-0.059
2
0.0060-0.019
0.0030 - 0.0049
0.0030 - 0.0049
0.060-0.199
3
0.020 - 0.039
0.0050 - 0.0079
0.0050 - 0.0079
0.200-0.899
4
0.040 - 0.069
0.0080 -0.0199
0.0080 -0.0199
0.900 - 2.999
5
0.070 - 0.089
0.0200 - 0.0499
0.0200 - 0.0499
3.000 -7.999
6
0.090-0.119
0.0500 - 0.0999
0.0500 - 0.0999
8.000 - 15.999
7
0.120-0.139
0.1000-0.1499
0.1000-0.2999
16.000 - 30.999
8
0.140-0.169
0.1500 -0.2599
0.3000 -0.4999
31.000 -39.999
9
0.170-0.189
0.2600 - 0.7999
0.5000 -0.7999
40.000 - 49.999
10
0.190-0.259
0.8000 - 1.000
0.8000 - 1.000
50.000 - 60.000
B1.2 Generating Challenge Gases
Two types of NPAP TTP audits are conducted, the ozone audit for which only ozone is
delivered to the monitoring station, and the blended gas audit, which includes one or
more of CO, SO2, and NO2.
Bl.2.1 Ozone Audit
When conducting an ozone audit, auditors generate the desired ozone concentrations with
the ozone generator in the GPT calibrator. For MVAs, the ozone-generated gases are
subsequently measured with a Level 2 ozone standard analyzer to verify the delivered
concentration. For FBAs, the calibrated ozone generator output is delivered to the
monitoring station without measured verification. Ozone concentrations for both MVAs
and FBAs are adjusted for the line-loss of ozone as described in Section B 1.4.
Bl.2.2 Blended Gas Audit
For the blended gas audit, auditors generate known concentrations of SO2, CO, and/or
NO2 to challenge the monitoring station gas analyzers. To do this, the auditor uses a gas
calibrator to dilute a standard gas from a high pressure cylinder containing known
concentrations of pollutant gases to generate the audit concentrations. For MVAs,
auditors employ a calibrated CO analyzer to directly measure and verify the CO
concentrations and determine the concentrations of the other gases using the known
relative concentrations of gases to CO. For FBAs, the challenge gas concentrations are
read directly from the display of the gas calibrator (whose MFCs have been properly
calibrated within the past three months and verified the day of audit conduct). To
generate NO2, a known amount of NO is provided by the gas calibrator in excess of the
desired NO2 concentration. The NO is then titrated to NO2 with a known amount of
ozone provided by the ozone generator in the GPT gas dilution calibrator. For MVAs, the
generated ozone concentration may be measured with the Level 2 ozone standard
analyzer for confirmation prior to performing GPT.
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B 1.2.2.1 Direct Read Nitrogen Dioxide Monitors
Direct-read NO2 monitors, or "true NO2" instruments are increasingly deployed at
monitoring stations, particularly at Photochemical Assessment Monitoring Stations
(PAMS) sites, where they are required. The current MVA process for auditing NOx
analyzers requires the monitoring station analyzer to have a calibrated NO-channel,
which is not incorporated in most of the currently available true NO2 instruments. EPA is
in the process of determining a robust method for conducting NPAP audits on these
instruments.
The NPAP does not currently prescribe TTP audit procedures for the following Federal
Equivalent Methods (FEMs) for true NO2 (current as of publication of this QAPP):
¦ FEM EQNA-0514-212 - Teledyne Advanced Pollution Instruments (API) Model
T500U CAPS N02 Analyzer
¦ FEM EQNA-1013-210 - Environnement S.A. AS32M CAPS N02 Analyzer
¦ FEM EQNA-0217-242 - Ecotech Serinus 60 CAPS N02 Analyzer
¦ FEM designation available from supplier - Aerodyne Research, Inc. CAPS NO2
Monitor
¦ FEM EQNA-0512-200 - Teledyne API Model T200UP Photolytic Conversion
NO2 Analyzer
¦ FEM EQNA-0320-256 - Teledyne API Model N500 CAPS NOx Analyzer
B1.3 Verifying Challenge Gas Concentrations for Measured Verification Audits
When performing MVAs, once challenge gases of the desired concentration have been
generated, the gas concentrations are verified for accuracy and stability by onboard gas
analyzers calibrated against NIST-traceable certified standards. Stability of gas
concentrations is evaluated as described in the NPAP TTP SOP by examination of
consecutive one-minute concentration averages.
The O3 analyzer (Level 2 ozone standard) calibration is verified and/or adjusted quarterly
against an SRP (Level 1 ozone standard). During the audit, a line loss factor is applied to
the ozone concentration to adjust for ozone loss through the PTFE delivery hose as
determined previously with the ozone line loss test. The ozone line loss test must have
been performed in the previous three months (quarterly).
For the blended gas audits, both CO and SO2 concentrations are verified by analysis of
CO concentration in the challenge stream. As both CO and SO2 are contained in the
NIST-traceable certified multiblend cylinder, the concentration of SO2 can be determined
from measuring the CO concentration in the challenge gas and calculating the SO2
concentration from the known relative certified concentrations of CO and SO2 in the
cylinder. Concentrations of CO are verified by analysis with the CO analyzer which is
calibrated each day of use with a NIST-traceable certified standard prior to the audit. The
calibration is established with a CO concentration in the range of 3.5 to 6.5 ppm (High
CO) and a known zero air matrix with CO < 0.01 ppm. The calibration is then verified
immediately after establishment, prior to beginning the audit by analysis of an
independent undiluted CO standard (Low CO) with a concentration in the range of 0.3 to
1.2 ppm.
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The concentration of NO2 in the blended gas challenge is determined by calculation of
the theoretical nominal concentration from the relative NO/CO concentration measured
by the CO verification analyzer and taking the ratio of the NO/CO in the blended gas
before GPT of NO with O3 in the gas calibrator and subtracting the NO remaining after
GPT as measured by the monitoring site NO/NOx monitor.
B1.4 Delivery of Challenge Gas
Once the challenge gas concentrations have been selected and generated (and verified for
MVAs), they are delivered to the station inlet probe. Challenge gases are delivered to the
station inlet probe via a single length (typically 150 feet) of (3/8-inch inner diameter)
FEP or PTFE Teflon® hose. As the hose is subjected to numerous cycles of winding and
unwinding as well as rough handling through transport and use, it is covered in a
protective stainless steel braid.
The delivery line and sample delivery flow path may only be constructed with materials
consisting of FEP Teflon®, borosilicate glass, and/or equivalent (per QA Handbook
Volume II, January 2017, PTFE Teflon® is an acceptable equivalent material) as required
in 40 CFR Part 58, Appendix E, Section 9(a). This allows for a consistent and
concentration stable gas delivery by minimizing scavenging of test pollutants during the
audit.
Several of the gases delivered for TTP audits are reactive and subject to losses within the
delivery hose: O3, SO2, and NO2. Particularly reactive is O3, which is subject to
unrecoverable losses within the delivery hose. The amount of loss can be measured via an
ozone line loss test (as described in the TTP SOP). Results from the ozone line loss test
are incorporated in the calculation of the ozone challenge gas concentration. SO2 and
NO2 typically are temporarily lost due to adsorption onto the interior surface of the
delivery hose, and require extensive time with each use with the gas flowing through the
hose to condition the hose for accurate concentration delivery. To ensure minimal
scrubbing of ozone when conducting audits, the delivery hose will need to be conditioned
with a low level of ozone if the audit system has been out of routine use or service for
several days or weeks. This may include generation of a low level concentration (e.g., 15
ppb) for several days if the system has been idle for up to one week, or a higher
concentration (e.g., 150 ppb) for several days if the system has been idle for over a
approximately one week. Regardless of frequency of use, the delivery hose must also be
conditioned for at least an hour prior to each audit with minimally 75 ppb ozone, and
higher concentrations (e.g., up to 500 ppb) are recommended prior to performing ozone
audits. The purpose of this conditioning is to deactivate any active sites within the
delivery hose, which can react with O3, NO/NO2, and/or SO2.
The connection of the delivery hose to the monitoring site inlet probe must be secure and
airtight to avoid unwanted dilution of the challenge gas with ambient air. Flow of the
challenge gas through the delivery hose must be sufficiently high to minimize residence
time (and the resulting desorption, adsorption, or reaction resulting in change of
concentration) within the hose, but a high flow rate can overpressurize the inlet of station
gas analyzers undergoing audit. For this reason, a vent tee is typically connected at the
extreme downstream end of the delivery hose to allow excess flow and pressure to vent to
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the atmosphere instead of pressurizing the monitoring station's gas analyzers.
Alternatively, a Teflon® bag may be tightly secured to the station inlet and will allow
sufficient venting to avoid overpressurizing the station analyzers. For sites operating
blower fans to pull in a constant supply of ambient air to a manifold, the blower fan will
be turned off and the fan exit may serve as the vent to ensure overpressurization does not
occur.
B2 Sampling Methods Requirements
For each NPAP TTP audit conducted, the auditor will document the concentrations and
associated concentration stability of the challenge gas. For MVAs, the measured
concentrations and their stability will be established and documented prior to notifying
the station operator to report a measurement. For FBAs, the auditor will document the
challenge gas concentration from the gas calibrator display and will document stability
when indicated by the monitoring station operator. The provided audit concentration
values and associated stability are required to complete the traceability of the test gas
provided to the monitoring site. For MVAs, these aspects are accomplished by annotating
the DAS output. For FBAs, the FS documents the concentration and concentration
stability within a hard copy form or electronic spreadsheet. The provided gas
concentrations are critical measurements and require measurement with calibrated
instruments traceable to certified standards. For MVAs, the measured concentration
values of the challenge gas are read from the CO analyzer (multiblend audit) or ozone
analyzer (ozone audit) response recorded by the DAS and documented within PEAT and
the stability of the challenge gas concentration is recorded as the CO analyzer or ozone
analyzer response in the DAS; however, these stability records are not documented
within PEAT. For FBAs, PEAT is not currently configured to record the pertinent values,
therefore auditors must document these critical measurements on hard copy forms or
within electronic spreadsheets.
The test gas generation and analysis sampling requirements for flow path materials, flow
rates, residence times, temperature, pressure, etc., are addressed in 40 CFR Part 50 in the
method appendices and in 40 CFR Part 58 in Appendices A and E and in appropriate
parts of the TTP SOP.
B2.1 Stability of Challenge Gas Concentrations
Determining stability is accomplished differently for MVAs and FBAs.
B2.1.1 Measurement Verification Audit Gas Concentration Stability
For MVAs, stability is determined by observing the one-minute average concentration
data from the analyzer as recorded on the DAS. For ozone, when at least the most recent
5 one-minute averages are within 1 ppb of the most recent five-minute average
concentration the concentration point is considered stable. For CO, when at least the most
recent 5 one-minute averages are within 10 ppb of the most recent five-minute average
concentration the point is considered stable. Also, the one-minute averages assessed
should not show a consistent positive or negative trend. If there are excursions outside of
the ranges described above or a consistent positive or negative trend is observed, the
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audit concentration is not stable. The auditor may need to allow a longer duration for the
system to demonstrate acceptable stability. If stability cannot be achieved, the FS will
troubleshoot, clean or repair the system as necessary, and repeat the process to ensure that
a stable audit concentration point can be achieved. Note that if the NPAP audit gas
generation system is altered during troubleshooting (i.e., cleaning, fixing a leak, etc.), the
CO analyzer or ozone analyzer must be re-calibrated and the audit repeated in entirety.
B2.1.2 Flow-Based Audit Gas Concentration Stability
For FBAs, stability is determined by observing the one-minute average concentration
data from the monitoring station undergoing audit. The auditor will begin generating the
desired concentration of the pollutant gas and will wait approximately 10 to 20 minutes to
notify the station operator to assess the concentration stability. The FS will advise the
station operator to evaluate the stability based on the comparison of the five most recent
one-minute average concentrations to be within 1 ppb (ozone, SO2, and NO/NOx/NCh) or
10 ppb (CO) of the most recent five-minute average concentration. Extended periods
(e.g., 30 minutes or more) may be required for the station operator to achieve a stable
concentration measurement. If stability cannot be achieved, the FS will troubleshoot,
clean or repair the system as necessary, and repeat the process to ensure that a stable
audit concentration point can be achieved.
B2.2 Environmental Conditions Measurements
The environmental temperature of the gas generation and delivery equipment must be
maintained within specifications (20 to 30°C) to ensure proper operation. Fluctuations
within the temperature range can also have an effect on the concentration stability of
audit concentrations, especially at lower concentration levels. Therefore, the temperature
must be held as constant as possible with minimal variation. FSs will log the
environmental temperatures (recommended to be 1-minute averages; however, the
averaging period should not exceed 5 minutes) for the gas generation and measurement
equipment (as applicable) to demonstrate the instruments were maintained within the
proper environmental conditions.
B2.3 Challenge Gas Flows
It is not critical that the flow of the challenge gas to the monitoring station or audit
system verification analyzers is measured accurately. However, it is important that there
is excess flow to the monitoring site probe, of which any excess will be released through
a vent, to ensure the challenge gas is not diluted with ambient air. This is ensured by
setting the output flow to approximately 16 L/minute. Similarly, for MVAs, there should
be excess flow to the verification gas analyzers as indicated by the manifold exit vent
flow rotameter; however, the magnitude of the flow is not critical and does not require
the manifold exit vent flow rotameter to be calibrated.
B3 Sample Handling and Custody
Since NPAP audits are conducted by generating and delivering gases onsite dynamically,
the process does not involve collecting and storing samples, therefore custody and
handling aspects do not apply to these audits as they would for processes for which
samples are collected. Auditors must ensure that equipment and standard materials are
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maintained in a secure environment under their control while away from the home base.
Policies and procedures for maintaining custody/control of equipment and materials are
described in the NPAP TTP SOP.
B4 Analytical Methods
Analytical methods involved in the NPAP TTP audit consist of those performed by the
auditor onsite when conducting an MVA to ensure the gas concentrations are accurate
and to determine the gas concentrations provided to the monitoring station.
Other analytical methods utilized in the NPAP relate to calibration (either adjustment of
verification) of an instrument or certification/verification of a standard material.
Calibration of an instrument involves comparison of the response from the instrument
undergoing calibration when analyzing a sample of known standard gas. For establishing
calibration, the instrument response is adjusted (standardized) to the theoretical nominal
concentration of the standard gas. Verification of a standard material involves analyzing
the material on an instrument calibrated with a certified material and assessing the
standard material's concentration (verification does not assign a new certified value). If a
standard material is shown to be out of tolerance, the material may be certified by a
properly-accredited laboratory (e.g., AA-PGVP compliant laboratory) and the material
assigned a new certified value. Certification is outside the scope of this QAPP.
B5 Quality Control Requirements
QC checks for the NPAP are limited to the periodic calibration verifications of the audit
devices and materials as described in Section A6. The CO analyzer employed for
concentration verification for MVAs is calibrated each day of use and the calibration is
verified by analysis of a NIST-traceable standard. The calibration verification analysis of
the Low CO standard must show the measured concentration is within ±3% of the
certified concentration. At the conclusion of the audit, the CO analyzer is challenged with
a NIST-traceable standard to characterize the analyzer calibration drift over the course of
the audit. Gas analyzers are not otherwise subjected to ongoing daily QC checks such as
typical periodic (e.g., nightly) span checks and zero checks for gas analyzers at
monitoring stations. Produced gases for challenging monitoring stations are checked for
quality by analyzing the CO concentration with the calibrated analyzer when performing
MVAs. Further, challenge gas concentrations measured by the CO analyzer are compared
to the gas calibrator programmed concentrations to ensure they are reasonable with
expectations; however, such reasonableness check comparisons are intended to be gross
error checks and do not have associated prescribed criteria. For FBAs, FSs will verify the
flow rate calibration of each dilution calibrator MFC at three flow rates across 10 to 90%
of the full-scale range. Each measured flow rate must be within ±2% of the flow transfer
standard reading.
B6 Instrument/Equipment Testing, Inspection, And Maintenance
Requirements
All instrumentation used to calibrate or analyze audit devices or materials will be
maintained in accordance with the manufacturer's guidelines for routine maintenance of
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that instrument. Instrument/equipment testing, inspection, and other maintenance checks
and procedures for each TTP audit system component are listed in the NPAP TTP SOP.
B7 Instrument Calibration and Frequency
Instruments and devices employed in NPAP TTP audits for making critical
measurements will be calibrated (calibration adjusted to comport with the standard or
verified to have met criteria through calibration verification) prior to use in NPAP audits
and will meet the criteria and be performed at the frequency specified in Table A6-1.
Critical measurements are those measurements which are required for determining the
challenge gas concentration.
B8 Inspection/Acceptance Requirements for Supplies and
Consumables
To minimize sources of variability within each audit system and between audit systems,
the equipment and materials are sourced from reliable vendors. Certified gases and audit
equipment are specified in the NPAP SOP. When purchasing gas standards for NPAP,
standard gases will be evaluated in the AA-PGVP.
Items purchased will be inspected to ensure they meet the acceptance requirements for
supplies and consumables. These specifications are detailed in the purchase documents,
which are maintained as a reference to ensure that items of the proper quality and
specification are received.
B9 Data Acquisition Requirements (Non-Direct Measurements)
Measured concentration data are polled from AQS annually, to encompass the most
recent 3 years of certified data from previous calendar years, to determine the NPAP
audit levels that all auditors will follow. These data are maintained within AQS and no
manipulations are performed on these data except to determine the maximum and
minimum concentrations reported during the calendar year.
AQS monitor and site metadata are retrieved from AQS using PEAT so that the auditor
can confirm the record in AQS against the actual observations on site. The metadata are
maintained within AQS and the auditor does not have the authority to manipulate or
change the data. However, the role of the auditor is to enter the correct information into
PEAT where it generates a report to assist the agency in correcting the data.
The OAQPS NPAP Lead may query or instruct a designee (e.g., EPA employee or
support contractor) to query NPAP TTP audit data from AQS to assess the data for
completeness, data quality, and/or other metrics of interest to the NPAP. Such queries of
AQS are performed using standard AQS query reports (AMP reports) and the process
does not permit alteration of data maintained within AQS.
BIO Data Management
B10.1 Overview of Data Management
Data generated within the NPAP are categorized in four ways:
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1. Monitoring site-specific data regarding the details of each site including historic
concentrations measured by the primary monitors for each of the parameters to be
audited: These data are maintained within AQS.
2. Certification, calibration, and verification data and records for audit devices and
materials employed to generate challenge gases and verify their concentrations:
Such records would include certificates of analysis for standard gases, calibration
and calibration verification records for gas calibrators, ozone generators, CO gas
analyzers, ozone analyzers, and ozone line loss tests. These records are
maintained by the FS for three years until transferred to the Regional office for
archival.
3. Records of settings and measurements made to generate and verify concentrations
of challenge gases and to verify environmental conditions of the audit laboratory
during the audit: Such records would include gas calibrator instrument settings
and readings from gas analyzers indicating concentrations and demonstrating
concentrations were stable when delivered to the monitoring station inlet, as well
as the temperature of the laboratory housing the audit equipment during the audit.
Such records may be hard copy forms (such as DAS outputs of graphs and
annotations or hand-recorded notes or observations) or electronic as recorded
within a DAS, electronic spreadsheet, or recorded in PEAT.
4. Results of audits: Such records would include the concentrations reported by the
monitoring site operator during an NPAP TTP audit and the resulting evaluation
report generated at the conclusion of the audit. Audit reports are typically
generated by PEAT (or in spreadsheet workbooks for FBAs), then uploaded and
maintained within AQS. The preliminary audit reports (hard copy or electronic)
are provided to the station operator and the Regional NPAP Lead.
B10.2 Data Processing and Reporting
Audit records are compiled on an annual basis covering the calendar year. Once
completed within PEAT (or uploaded to AQS separately for FBAs), audit results are
uploaded to the pre-production area within AQS and subsequently automatically loaded
to the AQS production database within a 7-day or 30-day period depending on whether
audit acceptance criteria were met. Regional NPAP Leads can intervene on the automatic
loading of NPAP TTP data to AQS by approving or rejecting the audit prior to the 7-day
or 30-day period.
B10.3 Unacceptable Results
Audit data results that fail to meet the EPA acceptance criteria listed in Table A6-2 for
Levels 3 through 10 are considered unacceptable (failing). For such unacceptable
evaluations, follow-up measures must be taken by the responsible monitoring
organization. The FS will notify the Regional EPA NPAP Lead of the failed audit and the
Regional EPA NPAP Lead will be responsible for communicating with the responsible
PQAO. Ideally, the SLT QA group would quickly perform a follow-up TTP audit
(equivalent to the annual PE) to confirm the NPAP result. If the NPAP TTP failure is
confirmed, the monitoring organization will be expected to take corrective actions which
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may involve drafting a corrective action plan (CAP), documenting the steps taken to
address the noncompliance, and conducting a follow-up audit to demonstrate acceptable
performance. If the SLT QA TTP audit does not confirm the NPAP TTP failure, the
Regional EPA NPAP Lead will coordinate with the FS to evaluate the TTP audit system
(e.g., assess the system performance at a certification laboratory) and may review
previous recent NPAP TTP audits for indications of drift, component failure (e.g., leaks),
or performance changes impacting audit system accuracy.
Timelines for preparing a CAP, rectifying the nonconformance, and performing a follow-
up PE will be determined by the Regional EPA NPAP Lead. The Regional EPA NPAP
Leads and the OAQPS NPAP Lead will, as appropriate and necessary, work with SLT
QA groups to investigate monitoring sites that fail audits to provide technical assistance
to identify and correct problems. In some cases, data invalidation could be a result, but
this action would be the result of the process and investigation between the SLT QA
group and the EPA Regional Office. Monitoring organizations that fail NPAP audits
should take corrective action as soon as possible to address issues to minimize the
amount of data impacted. Currently, the EPA Regional NPAP Leads are responsible for
reviewing the monthly audit results and corrective action summaries for their Region and
following up on potential problems identified during audits. As needed, the OAQPS
NPAP Lead may follow-up with Regional NPAP Leads to discuss problems at
monitoring sites that are indicated to be unresolved past 30 days in the corrective action
summary report.
B10.4 Data Reports
As indicated previously, the auditor distributes the audit results report to the monitoring
station operator and to the Regional NPAP Lead. Audit results that are unacceptable
(failing) are handled as described in Section BIO.3 of this QAPP.
The Regional NPAP Leads provide an individual final audit results report to the audited
monitoring agency. Regional requests for follow up and corrective action accompany the
final report. Regions will provide follow up responses to the OAQPS NPAP Lead from
the audited monitoring agency for failed audits.
EPA OAQPS prepares summary tables of the Regional and National Completeness
Results for the NPAP TTP audit program annually which are typically communicated
during annual training events and may be posted to the EPA AMTIC website. The
summary tables are prepared by compiling bias and completeness data by querying data
from standard AQS reports including: AMP500, AMP504, and AMP470.
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C. ASSESSMENT/OVERSIGHT
CI Assessments and Response Actions
Cl.l Performance Audits
CI.1.1 Performance Audit of NPAP Audit Systems
The objective of performing an audit on the FSs and audit systems is to provide an
independent assessment of the quality of the performance of the TTP mobile audit
systems and the support contractor, EPA, or PQAO staff FSs performing TTP audits.
The OAQPS NPAP Lead may request (and provide funding for the cost of) an
unannounced/unscheduled assessment of the performance of the Regional NPAP TTP
mobile audit systems and FS personnel by an NPAP Verification Laboratory (i.e., EPA
Region 4 or Region 7). The EPA NPAP Verification Laboratory will notify the OAQPS
NPAP Lead of the audit and will provide the OAQPS NPAP Lead the qualification
results when the audit has been completed. The concentrations of the pollutant gases
generated by the FS and Regional audit system will be compared to the verification
laboratory measurements to assess accuracy. The audit must minimally challenge Levels
2, 3, 4, and 5 (to mimic a routine TTP audit), and the tested FSs and audit systems must
show results within ±1.5 ppb or ±7%, whichever is greater, of the verification laboratory
results for each audit concentration level for each parameter. The NPAP Verification
Laboratory will send a summary report of results including the condition of the mobile
audit lab to the OAQPS NPAP Lead. If the results are unacceptable, the NPAP Regional
Verification Laboratory may repeat the qualification audit to confirm the initial results. If
confirmed, the unacceptably performing system will require repair, maintenance, and/or
recalibration and cannot be employed to conduct TTP audits until the performance is
demonstrated to be acceptable.
CI. 1.2 Verification of Audit Systems
The Region 7 mobile NPAP TTP laboratory, in addition to gas standards and equipment
from the Region 4 and Region 7 Criteria Pollutant NPAP support laboratories, will be
employed, as practical and as resources permit, for hands-on training of personnel and
verification of the Regional TTP audit systems and/or associated equipment or standards.
Each Regional TTP audit system is to be verified annually in addition to the individual
audit equipment and materials calibrations and verifications shown in Table A6-1.
Each Regional and self-implementing PQAO NPAP mobile audit system will be
independently evaluated preferably annually, but not to exceed a two-year period, by
measuring the provided pollutant gas concentrations from the Regional NPAP TTP audit
system undergoing verification with the Region 4 or Region 7 support laboratory or AA-
PGVP verification laboratory. The frequency of TTP mobile laboratory verification is
resource dependent and has allowed most labs to be verified at least once in two years.
To achieve verification, the tested FSs and audit systems must show results within ±1.5
ppb or ±7%, whichever is greater, of the verification laboratory results for each audit
concentration level for each parameter. The verification test must minimally challenge
Levels 2, 3, 4, and 5 (to mimic a routine TTP audit).
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CI.1.3 Technical Systems Audits of NPAP Regional Field Scientist Contractors
A TSA will be performed of each Regional contractor every three years by the OAQPS
NPAP Lead or a contractor (e.g., NPAP QA Support Contractor) on behalf of the
OAQPS NPAP Lead, who may be accompanied by an appropriate EPA technical staff
member to ensure that the contractor FS is adhering to this QAPP and the SOPs that
cover conducting audits, entering data, distributing data, and maintaining files. The TSA
will follow a set format based on the information contained in a checklist based on the
NPAP SOP. The TSA will be coordinated with the contractor FS manager. A report of
the results of the TSA will be sent in writing within 30 days of the conclusion of the audit
to the contractor manager for review. The contractor will determine the root cause of any
deficiencies and report the cause(s) and associated corrective action(s) taken to the
Regional NPAP Lead within 15 working days. The corrective actions will be approved by
the Regional NPAP Lead. All such TSA reports and corrective actions will be sent to the
OAQPS NPAP Lead upon completion and approval of the final corrective action
response.
CI.1.4 Independent Assessment of EPA Gas Certification Laboratories
The OAQPS NPAP Lead may periodically conduct or delegate an audit of the AA-PGVP
verification laboratories supporting the NPAP. The scope of such a TSA may include, but
not be limited to: observation of certification processes and procedures, examination of
calibration records, review of standard certifications, review of training records, and
review of governing QAPPs and/or SOPs.
CI.1.5 Independent Assessment of EPA Field Scientists
In EPA Regions for which EPA staff perform NPAP TTP audits, the EPA FSs and the
verification activities they perform for the program will be reviewed every three years in
a TSA by the OAQPS NPAP Lead, by a contractor on their behalf, or other appropriately
qualified auditor as designated by the OAQPS NPAP Lead.
The program element documentation that should be reviewed in these audits includes the
documentation of QA and QC checks and the associated acceptance criteria that are listed
in the NPAP TTP SOP:
1. The comparison of the Regional TTP O3 analyzer (Level 2 ozone standard) to the
Regional SRP must have been performed within the previous three months for
any conducted audits;
2. Delivery line ozone loss tests, performed quarterly;
3. Cylinder standard verifications, not to exceed 12 months from certification or
most recent verification;
4. Personnel training certifications (initial or re-certifications) completed annually;
5. Certification of the Regional TTP audit system (by the Region 4 or Region 7
verification system, or a system that has recently been certified by the Region 4 or
Region 7 verification system), completed within the past 12 months (not to
exceed 24 months).
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C1.2 Corrective Action
Cl.2.1 Monitoring Agency Corrective Actions
Monitoring agencies that receive unacceptable (failing) audit evaluations must take
corrective action to rectify the problem(s). Such corrective action is to be coordinated
with the Regional NPAP Lead as described in Section BIO.3. Follow up and corrective
action will be documented in the annual summary reports and/or annual tables.
Cl.2.2 NPAP Field Scientist and Support Laboratory Corrective Actions
When results of the internal QC checks or external QA audits (e.g., TSAs) demonstrate
nonconformances that impact data quality/traceability or exceed the limits specified in
this QAPP or in the supporting SOP(s), appropriate action will be instituted by the
OAQPS NPAP Lead, EPA Regional NPAP Lead, PQAO NPAP Lead, and/or the
contractor FS manager for problems that are determined to be in the implementation of
the NPAP TTP Program.
NPAP Regional Leads will provide reports of TSAs conducted on FSs to the FS manager,
who will work with the FS (whether an EPA Region staff member, PQAO staff member,
or a contractor auditor) to prepare a CAP. The CAP is to be completed within 30 days
and submitted to the NPAP Regional Lead. The CAP should include a corrective action
tracking (CAT) form included in Appendix A for each finding detailed in the TSA report
to ensure that the Regional NPAP Lead can monitor corrective actions and follow up to
ensure they are comprehensive, effective (address the problem and prevent recurrence),
and completed in a timely manner.
C1.3 Assessment (TSA) Reports
The Regional NPAP Lead managers will receive copies of reports for conducted systems
and performance audits and follow-up activities. The OAQPS NPAP Lead will receive
copies of all TSA reports and corrective action documentation.
NPAP FS contractors will submit monthly progress reports to the Regional Contract
Officer and Regional NPAP Lead on support activities for the NPAP.
C2 Reports to Management
Various reports of activities within the NPAP are to be completed so those responsible
for overseeing activities can direct resources appropriately. These various reports are
listed in Table C2-1 and further details are described below, as applicable.
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Table C2-1. List of Reports Required for NPAP
Type of Reports
Krequencv
Author / Recipient
Due l):ile
Progress Report
Monthly
Contractor audi lor. LPA Regional
Lead
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• An annual NPAP Data Summary Report or Table(s) of all the NPAP data to all
NPAP participants, EPA Regional NPAP points of contact, and the NPAP Lead
by May 31 of each year. The contractor may be asked to support presentation of
the NPAP Data Summary Report at the National Air (Management) Meetings.
In addition, the QA support contractor and the EPA NPAP Lead shall also communicate
by phone, e-mail, and/or in person on an as-needed basis.
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D. DATA VALIDATION AND USABILITY
D1 Data Review, Verification, and Validation Requirements
The criteria used to validate the data entered in AQS are listed in Table Dl-1. These
criteria have mostly been addressed and enforced within PEAT for MVAs. For FBAs, the
audit is conducted outside of PEAT and some of these criteria do not apply (as indicated
in Table Dl-1), and those that do must be verified manually. Items listed as critical must
be met or the TTP audit is invalid. Items listed as operational are important and required,
but do not result in invalidation of the audit.
Table Dl-1. NPAP TTP Audit Validation Criteria
CsiU'Sion
Pnriimclcr
Accepliince ( riU'rhi
ImporiiiiKT
Standards Certification
or Verification
CO analyzer calibration
gases: High CO (3.5 to
6.5 ppm) and Low CO
(0.3 to 1.2 ppm)
Certification or
concentration verified
within the previous 12
months (does not apply to
FBA)
Critical. PEAT will not
allow audit to occur if the
certification or most
recent verification date
exceeds 12 months.
Multiblend audit stock
gas
Certification or
concentrations verified
within the previous 12
months
Critical. PEAT will not
allow audit to occur if the
certification or most
recent verification date
exceeds 12 months.
Ozone analyzer
calibration
Calibration (established
or verified) within the
previous three months
against a Level 1 ozone
standard (SRP)
Critical. PEAT will not
allow audit to occur if the
calibration or most recent
verification date exceeds
3 months.
Equipment
Standardization
CO analyzer
Calibration established
each audit at zero with
ZAG output and High CO
standard.
Calibration verification
with low CO standard
must be ±3%.
(does not apply to FBA)
Critical. PEAT will not
allow audit to continue.
Zero air generator
CO concentration not to
exceed 20 ppb greater
than that of ultra-pure
zero air or zero air
scrubbed through an
external palladium (Pd)
scrubber (does not apply
to FBA)
Operational. If ZAG is
not scrubbing CO
sufficiently, place Pd
scrubber in line for all
audit procedures. If no
external Pd scrubber is
available, the audit is
aborted.
Ozone line loss test
Conducted within the
previous 3 months
covering four
concentrations from 10 to
200 ppb. Loss must be <
2.5 ppb at each level.
Critical. PEAT will not
allow audit to occur if the
test date exceeds 3
months or exceeds
acceptance criteria.
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Table Dl-1. NPAP TTP Audit Validation Criteria (continued)
Csili'Siitn
Piii'iiiiK'Icr
Accepliince ( riU'rhi
Import iincc
Equipment
Standardization
(continued)
Gas dilution calibrator
MFC
calibration/calibration
verification
Strongly recommended
within the past 3 months
and on the day of each
audit with flow at each
flow rate within ±2% of a
certified flow transfer
standard (minimum of 3
flows covering 10-90%
of flow range for
verification)
This is required for
performing FBAs.
Operational, not
critical to audit
conduct for MVAs.
Critical when
conducting FBAs.
Gas dilution calibrator
ozone generator
calibration
Concentrations
representing audit Levels
2 through 6 are within
±5% of the Level 1 (SRP)
or Level 2 ozone standard
Operational, not
critical to audit
conduct for MVAs.
Critical when
conducting FBAs.
Audit Concentrations
Gas concentration
challenge Levels
Must challenge
concentrations in Levels
2, 3, 4, and 5 in Table
Bl-1
Critical. Audit
incomplete and
cannot be evaluated
without
concentrations in
Levels 3, 4, and 5.
Audit Concentrations
Concentration
stability at each
concentration Level
point
Consecutive one-minute
average concentrations
must be within ±1 ppb for
ozone and ±10 ppb for
CO of the five-minute
average. Stability
annotated on DAS output
for MVAs. For FBAs, FS
must document stability.
Critical. PEAT does
not evaluate stability
and will not abort an
audit for
exceedance.
Audit Instrumentation
Environmental
conditions
Temperature where audit
instruments are operated
must be maintained
within 20 to 30°C
(excursions permitted but
must be < 30 minutes
total)
Critical. PEAT does
not evaluate
temperature and will
not abort an audit for
exceedance.
D2 Validation and Verification Methods
The PEAT application employed for preparing for, conducting and documenting, and
reporting NPAP audits includes built-in checks to advise auditors when certifications and
verifications are due for the standards and equipment. EPA has validated PEAT which
will accept only certain values and types of entries. Additionally, prior to completing an
audit in PEAT, automatic validation checks are performed to ensure that all required
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information has been recorded. PEAT will prompt the auditor to enter the missing
information and will not finalize the audit for reporting until the information is recorded.
Even with the advent of PEAT, Regional NPAP Leads are still tasked with validating and
approving TTP audits; however, if no validation efforts are taken, audit results are
automatically loaded into the production database of AQS within 7 days for acceptable
audits and 30 days for failing audits. Regional NPAP Lead approval of an audit pushes
the audit data into the AQS production database.
PEAT is not currently configured for conducting FBAs, therefore EPA Regional Leads
will verify data entries and calculations and validate FBAs prior to input into AQS, which
is performed manually by creating appropriate data files configured with AQS-ready
pipe-delimited data strings.
D3 Reconciliation with User Requirements
The FS will examine all data prior to submission to AQS and EPA data reviewers and
managers will ensure that the requirements are met as defined.
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REFERENCES
1. U. S. EPA Office of Research and Development. EPA Traceability Protocol for
Assay and Certification of Gaseous Calibration Standards. EPA 600/R-12/531.
May 2012.
2. U. S. EPA Office of Air Quality Planning and Standards. Quality Assurance
Project Plan for the Ambient Air Protocol Gas Verification Program. March 2010.
Available at (accessed November 2020):
https://www3.epa.gOv/ttnamtil/files/ambient/qaqc/pgvp-qapp-march2010v2.pdf
3. U. S. EPA. Technical Assistance Document. Transfer Standards for Calibration
of Air Monitoring Analyzers for Ozone. EPA-454/B-13-004. October 2013.
4. COMET SYSTEM, s.r.o. Instruction Manual - Programmable transmitter of
atmospheric pressure, temperature, relative humidity, and other derived humidity
values T7310, T7410 with RS232/RS485 serial output. IE-SNC-
T33(4)l l+T73(4)10-07. Available at (accessed November 2020):
https://www.cometsvstem.com/userfiles/dokumentv menu/48/ie-snc-t33 4 11-
t73 4 10.pdf
5. 40 CFR Part 58, Appendix A, available at (accessed November 2020):
https://www.ecfr. gov/cgi-bin/text-idx?node=pt40.6.58&rgn=div5
6. U. S. EPA. Guidance for Quality Assurance Project Plans. EPA QA/G-5.
EPA/240/R-02/009 December 2002. Available at (accessed December 2020):
https://www.epa.gov/sites/production/files/2015-06/documents/g5-final.pdf
7. U. S. EPA. Adequacy/Independence Criteria: Monitoring Rule Requirements and
Implementing Instructions, Revised July 23, 2008. Available at (accessed
November 2020): https://www.epa.gov/sites/production/files/202Q-
10/documents/npapadequacv072408.pdf
8. Quality Assurance Handbook for Air Pollution Measurement Systems. Volume II
- Ambient Air Quality Monitoring Program, EPA-454/B-17-001, U. S.
Environmental Protection Agency, January 2017. Available at (accessed
November 2020):
https://www3.epa.gov/ttn/amtic/files/ambient/pm25/qa/Final%20Handbook%20D
ocument%201 17.pdf
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APPENDIX A
Technical Systems Audit (TSA) Corrective Action Tracking (CAT) Form for the
Through the Probe (TTP) National Performance Audit Program (NPAP)
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NPAP Corrective Action Tracking (CAT) Form
Audited Entity: (Contractor, Region, Laboratory, etc.):
Date of Audit:
Finding # (cited in audit report/corrective action plan) :
Description of Finding (description from the audit report):
Describe action(s) taken to correct finding including date(s) corrective action(s)
completed:
Identify or list documentation (photos, copies of certificates or documents) of
corrective action taken and completed (please attach to this form).
Verified/Prepared by:
Date:
i i lis six-1 ion to hi-: compi.i ri o iiv i:i\\ s i \i i
Re\ icwcr's Comments.
Re\ iewed h\"
Dak-
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United States Office of Air Quality Planning and Standards Publication No. EPA-454/B-19-012
Environmental Protection Air Quality Assessment Division June 2021
Agency Research Triangle Park, NC
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