* A vo
l ®!
PRO"^
U.S. EPA Ambient Air Monitoring Protocol Gas
Verification Program
Annual Report CY 2020

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EPA-454/R-21-006
July 2021
U.S. EPA Ambient Air Monitoring Protocol Gas Verification Program
Annual Report CY 2020
U.S. Environmental Protection Agency
Office of Air Quality Planning and Standards
Air Quality Assessment Division
Research Triangle Park, NC

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Table of Contents
Acknowledgements	5
Acronyms and Abbreviations	6
1.0 Introduction	7
2.0 Implementation Summary	9
3.0 Survey and Verification Results	12
4.0 Summary and Conclusions	16
Appendix A QA Reports from Measurement Data Worksheets for 2020	19
Tables
Table 1. RAVL Verification Dates	10
Table 2. Gas Standards Sent to RAVLs	13
Table 3. MQOs for the AA-PGVP	14
Table 4. AA-PGVP CO and S02 Verifications	15
Table 5. AA-PGVP NO and NOx Verifications	15
Figures
Figure 1. AA-PGVP Flow Chart
Figure 2 Annual Survey
11
12

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Acknowledge m e nts
The following individuals and organizations are acknowledged for their contributions to this project:
US EPA, Office of Air Quality Planning and Standards
Douglas Jager
US EPA, Office of Research and Development
Bob Wright
US EPA Region 7
Michael Davis	Thien Bui	James Regehr
M o n i t o r i n g 0 rga n i z a t i o n s
EPA acknowledges the monitoring organizations that supported the AA-PGVP Annual Survey.
They include:
Alaska Department of Environmental Conservation
Canton City Health Department Air Pollution Control
Cherokee Nation, Oklahoma
Clark County, NV DAQEM
FDEP Ambient Monitoring Section
Forsyth County Environmental Affairs Department
Idaho Department of Health & Welfare-Env. Div.
Indiana Depart of Environ Management
Kentucky Division for Air Quality
Louisville, KY Metro Air Pollution Control District
Maricopa County Air Quality
Maryland Department of the Environment
Michigan Dept of Environment, Air Quality Division
Minnesota Pollution Control Agency, Div. of Air Quality
Missouri Laboratory Services Program
MT Dept of Environmental Quality, Air Quality Div.
New Jersey State Department of Environmental Protection
North Carolina Dept of Environmental Quality
Ohio EPA, Central District Office
Ohio EPA, Northeast District Office
Ohio EPA, Southeast District Office
Oklahoma Dept. of Environmental Quality, Air Qual. Div.
Oregon Department of Environmental Quality
South Carolina Department Health & Env. Control
South Coast Air Quality Management District
Washington State Department of Ecology
Wisconsin Dept of Natural Resources

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Acronyms and Abbreviations
AA-PGVP
Ambient Air Protocol Gas Verification Program
AMTIC
Ambient Monitoring Technology Information Center
AQS
Air Quality System
CFR
Code of Federal Regulations
CO
Carbon Monoxide
coc
Chain of Custody
CONC
Concentration
COVID-19
Coronavirus Disease 2019
EPA
Environmental Protection Agency
GMIS
Gas Manufacturer's Internal Standard
ID
Identification
MFC
Mass Flow Controller
MQO
Measurement Quality Objective
NIST
National Institute of Standards and Technology
N02
Nitrogen Dioxide
NOx
Nitrogen Oxides
NTRM
NIST Traceable Reference Material
NVLAP
National Voluntary Laboratory Accreditation Program
OAQPS
Office of Air Quality Planning and Standards
OAR
Office of Air and Radiation
OIG
Office of the Inspector General
ORD
Office of Research and Development
PQAO
Primary Quality Assurance Organization
PSI
Pounds per Square Inch
PSIG
Pounds per Square Inch Gauge
QA
Quality Assurance
QAPP
Quality Assurance Project Plan
QC
Quality Control
QTR
Quarter
RAVL
Regional Analytical Verification Laboratory
RD
Relative Difference
RPD
Relative Percent Difference
S02
Sulfur Dioxide
SOP
Standard Operating Procedure
SRM
Standard Reference Material
URL
Upper Range Limit

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1.0 Introduction
Backgrc nd Program Goals
The basic principles of the U.S. Environmental Protection Agency's (EPA) Traceability Protocol for the Assay
and Certification of Gaseous Calibration Standards (EPA, 2012)1 were developed jointly by EPA, the National
Bureau of Standards (now National Institute of Standards and Technology [N 1ST]), and specialty gas
producers over 40 years ago. At the time, commercially prepared calibration gases were perceived as being
too inaccurate and too unstable for use in calibrations and audits of continuous source emission monitors
and ambient air quality monitors2. The protocol was developed to improve the quality of the gases by
establishing their traceability to NIST Standard Reference Materials (SRMs) and to provide reasonably priced
products. This protocol established the gas metrological procedures for measurement and certification of
these calibration gases for EPA's Acid Rain Program under 40 Code of Federal Regulations (CFR) Part 75, for
the Ambient Air Quality Monitoring Program under 40 CFR Part 58, and for the Source Testing Program
under 40 CFR Parts 60, 61, and 68. EPA required monitoring organizations implementing these programs
("the regulated community") to use EPA Protocol Gases as their calibration gases. EPA revised the protocol
to establish detailed statistical procedures for estimating the total uncertainty of these gases. EPA's Acid
Rain Program developed acceptance criteria for the uncertainty estimate3.
Specialty gas producers prepare and analyze EPA Protocol Gases without direct governmental oversight. In
the 1980s and 1990s, EPA conducted a series of EPA-funded accuracy assessments of EPA Protocol Gases
sold by producers. The intent of these audits was to:
•	increase the acceptance and use of EPA Protocol Gases as calibration gases;
•	provide a quality assurance (QA) check for the producers of these gases; and
•	help users identify producers who can consistently provide accurately certified gases.
Either directly or through third parties, EPA procured EPA Protocol Gases from the producers, assessed the
accuracy of the gases' certified concentrations through independent analyses, and inspected the
1	EPA-600/R-12/531
2	Decker, C.E. et al., 1981. "Analysis of Commercial Cylinder Gases of Nitric Oxide, Sulfur Dioxide, and Carbon
Monoxide at Source Concentrations," Proceedings of theAPCA Specialty Conference on Continuous Emission
Monitoring-Design, Operation, and Experience, APCA Publication No. SP-43.
3	"Continuous Emission Monitoring," Code of Federal Regulations, Title 40, Part 75
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accompanying certificates of analysis for completeness and accuracy. The producers were not aware that
EPA had procured the gases for these audits.
The accuracy of the EPA Protocol Gases' certified concentrations was assessed using SRMs as the analytical
reference standards. If the difference between the audit's measured concentration and the producer's
certified concentration was more than ±2.0 percent or if the documentation was incomplete or inaccurate,
EPA notified the producer to resolve and correct the problem. The results of the accuracy assessments were
published in peer-reviewed journals and were posted on EPA's Technology Transfer Network website. The
accuracy assessments were discontinued in 1998.
In 2009, the Office of the Inspector General (OIG) published the report EPA Needs an Oversight Program for
Protocol Gases4. One of the report's findings suggested that EPA "does not have reasonable assurance that
the gases that are used to calibrate emissions monitors for the Acid Rain Program and continuous ambient
monitors for the nation's air monitoring network are accurate". OIG recommended that the Office of Air and
Radiation (OAR) implement oversight programs to assure the quality of the EPA Protocol Gases that are used
to calibrate these monitors. It also recommended that EPA's Office of Research and Development (ORD)
update and maintain the document Traceability Protocol for Assay and Certification of Gaseous Calibration
Standards to ensure that the monitoring programs' objectives are met.
In order to address the OIG findings for ambient air monitoring, the Office of Air Quality Planning and
Standards (OAQPS), in cooperation with two EPA Regional Offices, developed an Ambient Air Protocol Gas
Verification Program (AA-PGVP). The program established two gas metrology laboratories to verify the
certified concentrations of EPA Protocol Gases used to calibrate ambient air quality monitors. The program is
expected to ensure that producers selling EPA Protocol Gases participate in the AA-PGVP and provides end
users with information about participating producers and verification results.
The EPA Ambient Air Quality Monitoring Program's QA requirements, as described in Section 2.6.1 of 40 CFR
Part 58, Appendix A, include:
Gaseous pollutant concentration standards (permeation devices or cylinders of compressed gas)
used to obtain test concentrations for CO, S02, NO, and N02 must be traceable to either a National
Institute of Standards and Technology (NIST) Traceable Reference Material (NTRM) or a NIST-
certified Gas Manufacturer's Internal Standard (GMIS), certified in accordance with one of the
procedures given in reference 4 of this appendix. Vendors advertising certification with the
procedures provided in reference 4 of this appendix and distributing gases as "EPA Protocol Gas" for
ambient air monitoring purposes must participate in the EPA Ambient Air Protocol Gas Verification
Program or not use "EPA" in any form of advertising. Monitoring organizations must provide
information to the EPA on the gas producers they use on an annual basis and those POAOs
purchasing standards will be obligated, at the request of the EPA, to participate in the program at
least once every 5 years by sending a new unused standard to a designated verification laboratory.
4 https://www.epa.gov/office-inspector-general/report-epa-needs-oversight-program-protocol-gases-09-P-0235.pdf
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This program is considered a verification program because its current level of evaluation does not allow for a
large enough sample of EPA Protocol Gases from any one specialty gas producer to yield a statistically
rigorous assessment of the accuracy of the producer's gases. It will not provide end users with a
scientifically defensible estimate of whether gases of acceptable quality can be purchased from a specific
producer. Rather, the results provide information to end users that the specialty gas producer is
participating in the program and with information that may be helpful when selecting a producer.
Purpose lis Document
The purpose of this document is to report the activities that occurred in 2020 and provide the results of the
verifications performed.
This document will not explain the implementation of the AA-PGVP, the quality system or the verification
procedure. That information has been documented in the Implementation Plan, Quality Assurance Project
Plan (QAPP) and standard operating procedures (SOPs) that can be found on the AA-PGVP Web Page on the
Ambient Monitoring Technology Information Center (AMTIC)5.
2.0 Implementation Summary
Since the program implementation started in 2010, when most of the initial preparation work took place, no
major "new" implementation activities took place. However, EPA regional realignments and aging
infrastructure reduced the capabilities of this program. Due to these constraints, the EPA Region 2 Regional
Analytical Verification Laboratory (RAVL) ceased its active participation in the AA-PGVP in calendar year
2019. During 2020 the AA-PGVP began transitioning Region 2 operations to the Region 4 laboratory.
However, during 2020 the AA-PGVP continued to operate with only the Region 7 RAVL. Operations with only
a single RAVL resulted in the AA-PGVP unable to swap internal quality control samples and cylinders needing
confirmatory assay between two independent RAVLs. During 2020 EPA began reengineering the AA-PGVP
and as part of that process EPA began assisting the EPA Region 4 laboratory to serve as a replacement RAVL.
The following provides a brief explanation of the 2020 implementation process.
Producer Information Data Collection - In 2010 EPA sent out an Excel spreadsheet to each monitoring
organization to obtain information on the gas standard producers being used by the monitoring organization
and to determine their interest in participating in the program. In 2011, EPA began work with Research
Triangle Institute to develop a web-based survey that one point of contact for each monitoring organization
5 www.epa.gov/amtic/ambient-air-protocol-eas-verification-program
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could access. The intent was to make recording and evaluation of the survey information easier for the
monitoring organizations and EPA. This contracted survey work has since migrated to Battelle. Based on the
information obtained from monitoring organization surveys, EPA would develop a list of the specialty gas
producers being used by the monitoring organizations. From this list, EPA would attempt to perform
representative sampling of the standards from protocol gas production facilities by identifying regulatory
monitoring agencies that use standards from each of these producers. However, only 27 agencies
participated in the survey for 2020. With only limited survey results, a systematic selection of producers
could not be performed. The AA-PGVP performed assays on all cylinders submitted by regulatory monitoring
agencies. Representative sampling was not attempted for CY-2020. OAQPS is in the process of developing
an Air Quality System (AQS) database solution to upgrade and replace the specialty gas usage information
that is currently acquired through the contractor based annual questionnaire.
AA-PGVP Verification Dates - OAQPS worked with the Region 7 Regional Analytical Verification Laboratory
(RAVL) to establish verification dates as indicated in Table 1. However, due to the COVID-19 pandemic the
EPA Region 7 laboratory was shutdown during quarters 1 and 2 of calendar year 2020.
Table 1. RAVL Verification Dates
Quarter
Region 7
Cylinder Receipt
Analysis
Is
No later than Mar 20
Mar 30-April 10
2s
No later than June 17
June 22 - July 3
3
No later than Sept 4
Sept 14-Sept 25
4
No later than Nov 27
Dec 7 - Dec 18
Open
House
December 16, 2020
Table 1. RAVL Verification Dates
Note: * No assays were performed in Quarters 1 & 2 due to the COVID-19 pandemic.
Table 1 RAVL Open House - During Open House the RAVL allows specialty gas producers to visit and ask
questions regarding the laboratory processes and operations. During 2020 no specialty gas producers visited
the Region 7 RAVL.
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Flow of the AA-PGVP
Figure 1 provides a flow diagram of the implementation activities of the AA-PGVP. The major activities in
these steps are explained below. More details of these steps are found in the AA-PGVP Implementation Plan,
QAPP and SOPs.
Monitoring
Organizations
	*• Planning
— • ~ Data
Standards
Ambic it Cylinders,
COCs,; t Mfr. Certs.
Regional
Verification
Lab
Spec
Gas
Prod
NIST
possible
reanalysis
Technical
Technical
Assistance
Assistance
Audit
Data
Audit
Data
EPA
Web Site
End
User
Audit
Data&
Protocol
Audit
Data
EPA
Figure 1. AA-PGVP Flow Chart
1.	EPA sends e-rnails to the monitoring organization's points of contact to complete the AA-PGVP Survey. EPA compiles
information on specialty gas producers and the monitoring organizations that plan to participate. EPA tries to
schedule the monitoring organization in an appropriate verification quarter based on delivery of standards from the
specialty gas producer.
2.	The monitoring organizations order gas standards from specialty gas producers during the normal course of business.
If EPA cannot get a cylinder from the monitoring organization, and that producer is being used, EPA will invite the
producer to send a cylinder directly to an RAVL.
3.	The monitoring organizations send a new/unused standard, specialty gas certification and chain of custody form to
the RAVLs.
4.	The RAVLS analyze the cylinders and provide the validated results to OAQPS and the monitoring organizations.
5.	OAQPS reviews the data and sends verification results to the specialty gas vendors.
6.	At the end of the year, OAQPS compiles final results into a report, sends the report out to the specialty gas vendors
and posts it on the AA-PGVP AMTIC web page.
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3.0 Survey and Verification Results
Monitoring Organization Survey
Based upon the maximum capability of 40 gas cylinders per RAVL per year, the AA-PGVP selection goal, in
the following order, is:
1)	At least one gas standard from every specialty gas producer being used by the monitoring
community.
2)	If all specialty gas producers have been assessed at least once, then attempt to verify three
standards per specialty gas producer.
3)	If all specialty gas producers have been assessed three times, weigh additional verifications by
producer market share in the ambient air monitoring community.
In order to assess which specialty gas producers are used by the monitoring organizations, EPA annually uses
a web-based survey that each monitoring organization completes. Since 2016, EPA regulations found in 40
CFR Part 58 Appendix A 2.6.1 require monitoring organizations to annually provide this information.
However, as can be seen from Figure 2, participation in the annual survey has not improved since the 2016
monitoring rule revisions.
AA-PGVP Annual Survey
Participation Trend
300
250
200
150
100
50
0
.

	















r 81
r se

61




X
		/-

57
1


t
L 51
67


2011 2012 2013 2014 2015 2016 2017 2018 2019 2020
Year
•All AQS Agencies ^^^Agencies (S02, CO, N02) ^^"Surveyed
Figure 2 Annual Survey
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! " «as Standards Sent to RAVLs in Calen i .i ¦« < '•1"
Qtr
Cylinder ID
Pollutant
Lab
Producer
Facility
Agency
3
CC93605
CO
7
Air Gas
Chicago, IL
Missouri Laboratory Services
Program
4
FF55927
so2
7
Air Gas
Chicago, IL
Kentucky Div. for Air Quality
4
CC178285
NO, NOx
7
Air Gas
Chicago, IL
Polk County Air Quality
4
FF36562
NO, NOx
7
Air Gas
Chicago, IL
Kentucky Div. for Air Quality
4
BAL4148
CO, NO, NOx
7
Air Gas
Los Angeles, CA
South Coast Air Quality
Management District
3
SD15080
NO, NOx0
7
Matheson
Waverly, TN
Kansas Department of Health and
Environment
3
DT0011078*
NO, NOx0
7
PraxAir
Los Angeles, CA
(Sent by Producer)
3
DT0029223*
NO, NOx0
7
PraxAir
Toledo, OH
(Sent by Producer)
3
LL127859
NO, NOx°
7
PraxAir
Toledo, OH
State Hygienic Lab (Univ of Iowa)
4
LL197504
S02
7
Tier 5
Indianapolis, IN
Kentucky Div. for Air Quality
4
LL197501
NO, NOx0
7
Tier 5
Indianapolis, IN
Kentucky Div. for Air Quality
3
CC460552"
NO, NOx
7
WestAir
Anaheim, CA
San Diego Air Pollution Control
District
Table 2. Gas Standards Sent to RAVLs
Notes: * Direct submission by producer, assay results not blind to producer
** Cylinder opened prior to submission to EPA
CI NOx concentration provided by Producer as "informational only"; concentration not certified by Producer.
Verification Results
As indicated in 40 CFR Part 75 Appendix A, EPA Protocol Gases must have a certified uncertainty (95 percent
confidence interval) that must not be greater than plus or minus 2 percent (±2.0%) of the certified
concentration (tag value) of the gas mixture. This acceptance criterion is for the Acid Rain Program. The AA-
PGVP adopted the criteria as its data quality objective and developed a quality system to allow the RAVLs to
determine whether or not an individual protocol gas standard concentration was within ±2% of the certified
value. The Ambient Air Program has never identified an acceptance criterion for the protocol gases. Since
the AA-PGVP has not been established to provide a statistically rigorous assessment of any specialty gas
producer, the RAVLs report all valid results as analyzed, but it is suggested that any difference greater than
±4% is cause for concern. Information related to the analytical reference standards, analytical instruments
and methods used, the data reduction procedures and the data assessment procedures are all found in the
AA-PGVP QAPP and SOP and are not repeated in this report. Table 3 provides the measurement quality
objectives (MQOs) that are included in the AA-PGVP QAPP (Table 7-1 of the QAPP). The acceptance criteria
in Table 3 were met for each day of verification. In addition, conformance to these requirements can be
found in the measurement data worksheets that are generated for each comparison run and are available
upon request. Appendix A provides a report of the quality control (QC) checks associated with each
verification run. Table 4 provides the verification results for CO and S02, and Table 5 provides the NOx
results.
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aOs for the AA-PGVP
Requirement
Frequency
Acceptance Criteria
Protocol Gas
Doc. Reference
Comments
Completeness
All standards analyzed
95%

Based on an anticipated 40
cylinders per lab per year.
Quarterly Flow
Calibration
Quarterly -no more than
1 mo. before verification
Calibration flow
accuracy within +1%
2.3.7
Using flow primary
standard
Calibrator Dilution
Check
Quarterly -within 2 weeks
of assay
+ 1% RD
2.3.5.1
Second SRM. Three or
more discrete
measurements
Analyzer
Calibration
Quarterly-within 2 weeks
of assay
+ 1% RPD (each point)
Slope 0.89-1.02
2.1.7.2
5 points between 50-90%
of upper range limit of
analyzer + zero point
Zero & Span
Verifications
Each day of verification
SE mean < 1% and
accuracy + 5% RD
2.1.7.3, 2.3.5.4
Drift accountability. 3
discrete measurements of
zero and span
Precision Test1
Day of Verification
+ 1% RD standard
error of the mean
2.3.5.4
SRM at conc. >80% of
analyzer URL
Routine Data
Check
Any Standard with Value
>2% Tag Value
NA

Sample run three times to
verify value.
Lab Comparability
2/year
+ 2 % RPD
NA
Sample run three average
value used.
Standards Certification
Primary flow
standard
Annually-Certified by
NVLAP certified lab
1.0 %
NA
Compared to NIST
Traceable
NISTSRMs
Expiration date SRM
pressure > 150 psig


Will follow NIST
recertification
requirements
Table 3. MQOs for the AA-PGVP
1 The precision test does not need to be accomplished if analyzer calibrated on same day as analysis.
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Table 4. 2020 AA-PGVP CO and S02 Verifications*
Qtr
Lab
Producer
Facility
Cylinder
ID
Pollutant
Assay
Cone
Producer
Cone
% Bias
95%
Uncertainty
4
7
Air Gas
Los Angeles, CA
BAL4148
CO
909.5
907.7
0.19
0.27
3
7
Air Gas
Chicago, IL
CC93605
CO
220.4
220.1
0.14
0.26
4
7
Air Gas
Chicago, IL
FF55927
so2
5.000
5.042
-0.82
0.42
4
7
Tier 5
Indianapolis, IN
LL197504
so2
49.42
49.5
-0.15
0.21
Table 4. AA-PGVP CO and S02 Verifications
Notes: t An Estimate for the national usage for specific protocol gas producers cannot be determined
due to lack of participation in annual survey
Table 5. 2020 AA-PGVP NO and NOx Verifications*
Qtr
Lab
Producer
Facility
Cylinder ID
Pollutant
Assay
Cone
Producer
Cone
% Bias
95%
Uncertainty
3
7
PraxAir
Toledo, OH
DT0029223*
NO
25.54
25.4
0.55
0.18
3
7
PraxAir
Los Angeles, CA
DT0011078*
NO
49.69
49.7
-0.02
0.18
3
7
PraxAir
Toledo, OH
LL127859
NO
25.2
25.1
0.38
0.18
3
7
WestAir
Anaheim, CA
CC460552"
NO
15
14.88
0.82
0.19
4
7
Air Gas
Los Angeles, CA
BAL4148
NO
44.88
45
-0.27
0.17
3
7
Matheson
Waverly, TN
SD15080
NO
19.55
19.96
-2.03"
0.19
4

Air Gas
Chicago, IL
CC178285
NO
10.024
9.886
1.4
D.5
4 I 7 | Air Gas | Chicago, IL | FF36562 NO | 9.644 | 9.439 | 2.17" | 0.52
4
7
Tier 5
Indianapolis, IN
LL197501
NO
48.14
49.5
-2.75
0.16
3
7
PraxAir
Toledo, OH
DT0029223*
NOx°
25.54
25.7
-0.62
0.21
3
7
PraxAir
Los Angeles, CA
DT0011078*
NOx0
49.75
49.9
-0.3
0.21
3
7
PraxAir
Toledo, OH
LL127859
NOx0
25.19
25.4
-0.83
0.22
3
7
WestAir
Anaheim, CA
CC460552"
NOx
15.06
14.97
0.63
0.22
4
7
Air Gas
Los Angeles, CA
BAL4148
NOx
45.21
45.11
0.23
0.17
3
7
Matheson
Waverly, TN
SD15080
NOx0
19.57
20.01
-2.22"
0.22
4
7
Air Gas
Chicago, IL
CC178285
NOx
10.063
9.886
1.79
0.41
4
7
Air Gas
Chicago, IL
FF36562
NOx
9.986
9.56
4.46
0.41
4
7
Tier 5
Indianapolis, IN
LL197501
NOx0
48.25
50
-3.49
0.17
Table 5. AA-PGVP NO and NOx Verifications
Notes: * Direct submission by producer, assay results not blind to producer
** Cylinder opened prior to submission to EPA
t An Estimate for the national usage for specific protocol gas producers cannot be determined
due to lack of participation in annual survey
Li % Bias within the ±2% acid rain criteria acceptance criterion when RAVL 95% Uncertainty is considered
CI NOx concentration provided by Producer as "informational only"; concentration not certified by Producer.
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Twelve cylinders were received by the AA-PGVP during calendar year 2020. Ten of these cylinders were
received from regulatory monitoring agencies to support the AA-PGVP. Two of the cylinders were directly
submitted from protocol gas producers. The assay results for all cylinders are included in Tables 4 and 5 but
some are qualified with footnotes to denote that they do not fully meet the assessment requirements for the
AA-PGVP. The NO cylinders directly submitted by Praxair were not blind to the producer. The NO cylinder
provided by San Diego County Air Pollution Control District (SDAPCD) was opened by the agency prior to
shipment to EPA. AA-PGVP requires that cylinders be unopened prior to receipt at the RAVL. While opened
prior to receipt at the RAVL, the WestAir cylinder from SDAPCD is considered a valid sample based on the
good agreement between EPA's independent assay and the assay results of the producer certified
concentrations.
All results for the CO and S02 standards were within the ±2% acid rain criteria acceptance criterion. Two of
the nine protocol gas cylinder standards assayed for NOx (Cylinder IDs: FF36562 and LL197501) did not meet
the ±2% acid rain criteria acceptance criterion. Cylinder ID FF36562 was also above the ±4% AA-PGVP action
level criteria for NOx. Additionally, Cylinder ID FF36562 also approached the ±2% acid rain criteria acceptance
criterion for NO, but based on the RAVL's 95% uncertainty value of 0.52% it was assessed in this annual
report as meeting the ±2% acid rain criteria acceptance criterion for NO. Cylinder ID LL197501 exceeded the
±2% acid rain criteria acceptance criterion for NO in addition to NOx. The assay for Cylinder ID SD15080 was
found to approach the ±2% acid rain criteria acceptance criterion for NOx and NO but was assessed in this
annual report as meeting these criteria when the RAVL's 95% uncertainty was considered. The NOx
concentration for five cylinders assayed were provided as "informational only" by the Producers and were
not certified. While not certified, these NOx concentrations were assayed by the AA-PGVP to provide context
to for the certified NO component in the protocol gas cylinder standard.
In 2020 the AA-PGVP operated with a single RAVL. As such, the quality assurance designated for the
laboratory intercomparison of the internal standards could not be performed. Protocol gas producers not
meeting the ±2% acceptance criteria were offered, and accepted, an opportunity to perform their own
confirmatory assay of the cylinders. The results of these producer independent assays were not provided to
EPA to include in this report.
4.0 Summary and Conclusions
General -
The AA-PGVP is implementing a verification process that is blind to the specialty gas producers. One of goals
of the ambient air monitoring rule (published March 28, 2016) was for the verifications performed by the
RAVLs to be focused more on our ambient air monitoring organizations rather than as a resource to be
utilized by specialty gas producers for their own quality assurance. The purpose of the program (blind
verification of gas cylinders provided by monitoring organizations) cannot be accomplished if EPA relies on
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the specialty gas producers to submit cylinders for assessment. Of the 12 protocol gas cylinder standards
submitted for analysis only two cylinders were directly submitted by gas producers.
While the program is successfully implementing a blind verification process, only 12 cylinders were analyzed
in 2020 or 15% of the AA-PGVP goal of 80 cylinders annually. EPA's single RAVL was only able to operate for
the last half of 2020 due to the COVID-19 pandemic. Two of the 12 cylinders were sent direct from the
producers and another cylinder was opened by the submitting agency before sent to EPA. These twelve-
cylinder submissions resulted in only 22 verifications performed in 2020 (some cylinders are a blend of
multiple gas standards). Results show that 3 of the 22 verifications (14%) failed the ±2% Acid Rain Program
criteria. It is difficult to assess the extent to which this issue impacts our ambient air monitoring networks in
2020 due to the low utilization of the RAVLs by our monitoring programs and low participation rate in the
annual protocol gas questionnaire. In 2020 there were 25 EPA protocol gas production facilities in operation
nationally. It is uncertain how many of these facilities were used in the ambient air monitoring networks in
2020. Additionally, of the 25 protocol gas production facilities operating, only 7 were verified by our ambient
air monitoring program in calendar year 2020.
Survey Participation Improvement -
Since its inception, the AA-PGVP has relied on an annual survey to determine which gas producers and
facilities are used for generating CO, S02, and N02 test atmospheres from protocol gas cylinder standards.
Participation in the annual survey was initially voluntary. To improve the participation rate and to more
completely document which protocol gas producers are utilized by our ambient air monitoring organizations,
in 2016 states using protocol gases were required to complete the survey every year. While it was thought at
the time that this regulatory requirement would increase the participation and create a comprehensive list of
the protocol gas producers used in the national network, the survey participation rate has not improved. In
calendar year 2020 participation in the annual questionnaire was about 17% of the monitoring agencies that
operate CO, S02, N02 ambient air analyzers. OAQPS is actively assessing EPA's AQS database as an
alternative solution to gather this information. See Data Management Improvement section below for
further details.
RAVL Participation Improvement -
Since the monitoring rule was revised in 2016, the AA-PGVP has made progress in achieving blind
verifications of the protocol gas cylinders used in our ambient air monitoring networks. However, the
program continues to not achieve its goal of having every Primary Quality Assurance Organization (PQAO)
submit an unused cylinder at least once every five years for verification. The AA-PGVP's goal to perform 80
protocol gas verifications each year and to strategically select these protocol cylinders to represent the
national ambient air monitoring networks was not achieved in calendar year 2020. Only twelve protocol gas
cylinder standards were submitted by seven PQAOs in 2020 to support this national program. Region 7
assayed all the cylinders received in 2020. Four of the seven monitoring programs submitting protocol gas
cylinders for the AA-PGVP were clustered in proximity to the Region 7 laboratory. A better national sampling
of monitoring programs and protocol gas producers continues to be needed. Diminished assay capacity was
due to only having a single RAVL in 2020 and operations being impacted by the COVID-19 pandemic. OAQPS
is working to add assay capacity in 2021 and 2022 by using the Region 4 laboratory as an additional RAVL.
Page 17 of 24

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Quality System Improvement -
The Quality Assurance Project Plan (QAPP) has not been updated since the inception of the program in 2010.
Since calendar year 2010, changes to the program have occurred, including regulatory changes in 2016.
These documents need to be reconciled with current program practices and regulatory requirements.
OAQPS began reviewing and revising the QAPP for this program in 2020 with a goal of having a draft revised
QAPP by the end of 2021.
In 2020, the AA-PGVP operated with a single RAVL. As such, the quality assurance designated for the
laboratory intercomparison of the internal standards could not be performed. OAQPS is currently working
with EPA Region 4 to begin using their laboratory as a second RAVL. The Region 4 RAVL is scheduled to
become operational the end of calendar year 2021.
Data Management Improvement -
The AA-PGVP has relied solely on the annual survey for determining which protocol gas standard producers
are used in the national ambient air monitoring networks. The annual survey was originally a voluntary
program and later in 2016 it became a regulatory requirement. Neither implementation of this process has
proven to be fully effective. The data management practices for conducting the annual survey and storing its
results are not optimized to be readily reconciled with the data produced by the RAVLs. Additionally, data
validation and data entry business rules are needed to ensure the accuracy of the data submitted for both
portions of this program (protocol gas survey and RAVL analytical results). Once accomplished this will
enable both datasets to be readily assessed with respect to monitoring organization, PQAO, and producer
production facility. Data entry errors on the annual survey and chain of custody forms and the lack of key
fields impede analysis of the information collected for this program. A revised spreadsheet based COC form
with data validation will be used in calendar 2021 to help address so these issues.
OAQPS is actively investigating an AQS database solution to replace some of the data management practices
historically performed in the program. This includes assessing the feasibility of making modifications to the
current AQS "QA-Transaction" file format for the single point quality control checks and annual performance
audits. The proposed modifications being investigated would allow for documenting the protocol gas
producer and facility of the protocol gas cylinder used for generating the test atmospheres for each of these
checks. Utilizing this modified AQS data submission process would allow EPA to document 100% of the
protocol gas production facilities used in the ambient air monitoring networks as opposed to the current
process which has only been 44% effective between 2015-2020.
Page 18 of 24

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Appendix A njorts from Measureme 11 11 'ta Worksheets for 2020
Ambient Air Protocol Gas Verification Program
QA Reports from Measurement Data Worksheets for 2020
During the verification process, the Regional Air Verification Laboratories perform a number of quality
control checks that are recorded on the Measurement Data Worksheets. This information is reported and
saved along with the verification reports. The following sheets represent the quality control for all
verifications that were implemented in 2020.
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QA Requirements Summary, Region 7 - 3rd Quarter of 2020
OA Requirement	Result	Status

Primary SRM Cylinder Expiration Date
13-Apr-24
Primary SRM Gas Standard OK
SRM Gas Standards
Primary SRM Cylinder Pressure >150 psi
2000
Primary SRM cylinder pressure is OK
SRM Dilution Check Cylinder Expiration Date
20-Sep-21
Dilution Check SRM Gas Standard OK

Dilution Check SRM Cylinder Pressure >150 psi
675
Dilution check SRM cylinder pressure is OK

High Flow Standard Expiration Date
8-Jan-21
Standard OK
Laboratory Flow Standard
Low Flow Standard Expiration Date
8-Jan-21
Standard OK

Ultra Low Flow Standard Expiration Date
21-Jan-21
Standard OK

Calibrator Flow Calibration within 2 weeks of assay
13-Sep-20
Calibrator flow calibration within 2 weeks of assay
Calibrator (mass flow controllers)
Calibrated High Flow MFC Slope Range = 0.99 - 1.C
0.9999990
High MFC OK

Calibrated Low Flow MFC Slope Range = 0.99 - 1.C
0.9999907
Low MFC OK

Analyzer Calibration within 2 week of assay
13-Sep-20
Analyzer calibration within 2 weeks of assay

Estimate of Uncetainty < 1 % at point #1 (>80% URL
0.25%
Assay may be conducted at this concentration

Estimate of Uncetainty < 1 % at point #2
0.26%
Assay may be conducted at this concentration
Carbon Monoxide Gas Analyzer
Estimate of Uncetainty < 1 % at point #3
0.27%
Assay may be conducted at this concentration

Estimate of Uncetainty < 1 % at point #4
0.28%
Assay may be conducted at this concentration

Estimate of Uncetainty < 1 % at point #5 (~50% URL
0.31 %
Assay may be conducted at this concentration

Analyzer slope is within 0.98-1.02
1.0012
Analyzer Slope is acceptable
Dilution Check
Dilution Check Date within 2 weeks of assay
14-Sep-20
Dilution check within 2 weeks of assay
Dilution Check Relative % Difference < 1%
I
O
o
sP
0s
Dilution Check RSD is OK



Day of Assay Zero/Span Check
Day of Assay Zero Check - Std. Error < 1 % Std. Error is okay.
Day of Assay Zero Check - Relative Difference < 5°/ RD is okay.
Zero Gas Std. Error is OK
Zero Gas RD is OK
Day of Assay Span Check - Std. Error < 1 %
Std. Error is okay.
Span Gas Std. Error is OK

Day of Assay Span Check - Relative Difference <5°/ RD is okay.
Span Gas RD is OK
Page 20 of 24

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QA Requirements Summary, Region 7 - 3rd Quarter of 2020
QA Requirement	Result	Status

Primary SRM Cylinder Expiration Date
8-Aug-23
Primary SRM Gas Standard OK
SRM Gas Standards
Primary SRM Cylinder Pressure >150 psi
550
Primary SRM cylinder pressure is OK
SRM Dilution Check Cylinder Expiration Date
1-Feb-24
Dilution Check SRM Gas Standard OK

Dilution Check SRM Cylinder Pressure >150 psi
800
Dilution check SRM cylinder pressure is OK

High Flow Standard Expiration Date
8-Jan-21
Standard OK
Laboratory Flow Standard
Low Flow Standard Expiration Date
8-Jan-21
Standard OK

Ultra Low Flow Expiration Date
21-Jan-21
Standard OK

Calibrator Flow
Calibration within
2 weeks of assay
13-Sep-20
Calibrator
flow calibration within 2 weeks of assay
Calibrator (mass flow controllers)
Calibrated High
Flow MFC Slope
Range = 0.99 - 1.C
0.9999990
High MFC
OK

Calibrated Low
Flow MFC Slope
Range = 0.99 - 1.C
0.9999915
Low MFC
OK

Analyzer Calibration within 2 weeks of assay
15-Sep-20
Analyzer calibration within 2 weeks of assay

Estimate of Uncetainty < 1% at point #1 (>80% URL
0.27%
Assay may be conducted at this concentration
Oxides of Nitrogen Gas Analyzer
NO Portion
Estimate of Uncetainty < 1% at point #2
0.28%
Assay may be conducted at this concentration
Estimate of Uncetainty < 1% at point #3
0.29%
Assay may be conducted at this concentration
Estimate of Uncetainty < 1% at point #4
0.31%
Assay may be conducted at this concentration

Estimate of Uncetainty < 1% at point #5 (~50% URL
0.34%
Assay may be conducted at this concentration

Analyzer slope is within 0.98-1.02
1.0005
Analyzer Slope is acceptable

Analyzer Calibration within 2 week of assay
15-Sep-20
Analyzer calibration within 2 weeks of assay

Estimate of Uncetainty < 1% at point #1 (>80% URL
0.32%
Assay may be conducted at this concentration
Oxides of Nitrogen Gas Analyzer
NOx Portion
Estimate of Uncetainty < 1% at point #2
0.33%
Assay may be conducted at this concentration
Estimate of Uncetainty < 1% at point #3
0.34%
Assay may be conducted at this concentration
Estimate of Uncetainty < 1% at point #4
0.36%
Assay may be conducted at this concentration

Estimate of Uncetainty < 1% at point #5 (~50% URL
0.39%
Assay may be conducted at this concentration

Analyzer slope is within 0.98-1.02
0.9967
Analyzer Slope is acceptable
Dilution Check
Dilution Check Date within 2 weeks of assay
14-Sep-20
Dilution check within 2 weeks of assay
Dilution Check Relative % Difference < 1%
-0.407%
Dilution Check RSD is OK

Day of Assay Zero Check - Std. Error < 1% Std. Error is okay.
Zero Gas Std. Error is OK
Day of Assay Zero/Span Check
NO Portion
Day of Assay Zero Check - Relative Difference < 5°/ RD is okay.
Zero Gas RD is OK
Day of Assay Span Check - Std. Error < 1% Std. Error is okay.
Span Gas Std. Error is OK

Day of Assay Span Check - Relative Difference <5°/ RD is okay.
Span Gas RD is OK


Day of Assay Zero Check - Std. Error < 1% Std. Error is okay.
Zero Gas Std. Error is OK
Day of Assay Zero/Span Check
NOx Portion
Day of Assay Zero Check - Relative Difference < 5°/ RD is okay.
Zero Gas RD is OK
Day of Assay Span Check - Std. Error < 1% Std. Error is okay.
Span Gas Std. Error is OK

Day of Assay Span Check - Relative Difference <5°/ RD is okay.
Span Gas RD is OK
Page 21 of 24

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QA Requirements Summary, Region 7 - 4th Quarter of 2020
OA Requirement	Result	Status

Primary SRM Cylinder Expiration Date
20-Sep-21
Primary SRM Gas Standard OK
SRM Gas Standards
Primary SRM Cylinder Pressure >150 psi
1900
Primary SRM cylinder pressure is OK
SRM Dilution Check Cylinder Expiration Date
20-Sep-21
Dilution Check SRM Gas Standard OK

Dilution Check SRM Cylinder Pressure >150 psi
675
Dilution check SRM cylinder pressure is OK

High Flow Standard Expiration Date
8-Jan-21
Standard OK
Laboratory Flow Standard
Low Flow Standard Expiration Date
8-Jan-21
Standard OK

Ultra Low Flow Standard Expiration Date
21-Jan-21
Standard OK

Calibrator Flow Calibration within 2 weeks of assay
6-Dec-20
Calibrator flow calibration within 2 weeks of assay
Calibrator (mass flow controllers]
Calibrated High Flow MFC Slope Range = 0.99 - 1.C
0.9999993
High MFC OK

Calibrated Low Flow MFC Slope Range = 0.99 - 1.C
0.9999844
Low MFC OK

Analyzer Calibration within 2 week of assay
7-Dec-20
Analyzer calibration within 2 weeks of assay

Estimate of Uncetainty < 1% at point #1 (>80% URL
0.38%
Assay may be conducted at this concentration

Estimate of Uncetainty < 1% at point #2
0.39%
Assay may be conducted at this concentration
Carbon Monoxide Gas Analyzer
Estimate of Uncetainty < 1% at point #3
0.41%
Assay may be conducted at this concentration

Estimate of Uncetainty < 1% at point #4
0.44%
Assay may be conducted at this concentration

Estimate of Uncetainty < 1% at point #5 (~50% URL
0.48%
Assay may be conducted at this concentration

Analyzer slope is within 0.98-1.02
1.0029
Analyzer Slope is acceptable
Dilution Check
Dilution Check Date within 2 weeks of assay
7-Dec-20
Dilution check within 2 weeks of assay
Dilution Check Relative % Difference < 1%
I
O
o
sP
0s
Dilution Check RSD is OK



Day of Assay Zero/Span Check
Day of Assay Zero Check - Std. Error < 1 % Std. Error is okay.
Day of Assay Zero Check - Relative Difference < 5°/ RD is okay.
Zero Gas Std. Error is OK
Zero Gas RD is OK
Day of Assay Span Check - Std. Error < 1 %
Std. Error is okay.
Span Gas Std. Error is OK

Day of Assay Span Check - Relative Difference <5°/ RD is okay.
Span Gas RD is OK
Page 22 of 24

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QA Requirements Summary, Region 7 - 4th Quarter of 2020
QA Requirement	Result	Status

Primary SRM Cylinder Expiration Date
8-Aug-23
Primary SRM Gas Standard OK
SRM Gas Standards
Primary SRM Cylinder Pressure >150 psi
475
Primary SRM cylinder pressure is OK
SRM Dilution Check Cylinder Expiration Date
1-Feb-24
Dilution Check SRM Gas Standard OK

Dilution Check SRM Cylinder Pressure >150 psi
800
Dilution check SRM cylinder pressure is OK

High Flow Standard Expiration Date
8-Jan-21
Standard OK
Laboratory Flow Standard
Low Flow Standard Expiration Date
8-Jan-21
Standard OK

Ultra Low Flow Expiration Date
21-Jan-21
Standard OK

Calibrator Flow
Calibration within
2 weeks of assay
6~Dec~20
Calibrator
flow calibration within 2 weeks of assay
Calibrator (mass flow controllers)
Calibrated High
Flow MFC Slope
Range = 0.99 - 1.C
0.9999993
High MFC
OK

Calibrated Low
Flow MFC Slope
Range = 0.99 - 1.C
0.9999844
Low MFC
OK

Analyzer Calibration within 2 weeks of assay
10-Dec-20
Analyzer calibration within 2 weeks of assay

Estimate of Uncetainty < 1% at point #1 (>80% URL
0.24%
Assay may be conducted at this concentration
Oxides of Nitrogen Gas Analyzer
NO Portion
Estimate of Uncetainty < 1% at point #2
0.25%
Assay may be conducted at this concentration
Estimate of Uncetainty < 1% at point #3
0.26%
Assay may be conducted at this concentration
Estimate of Uncetainty < 1% at point #4
0.27%
Assay may be conducted at this concentration

Estimate of Uncetainty < 1% at point #5 (~50% URL
0.30%
Assay may be conducted at this concentration

Analyzer slope is within 0.98-1.02
1.0006
Analyzer Slope is acceptable

Analyzer Calibration within 2 week of assay
10-Dec-20
Analyzer calibration within 2 weeks of assay

Estimate of Uncetainty < 1% at point #1 (>80% URL
0.24%
Assay may be conducted at this concentration
Oxides of Nitrogen Gas Analyzer
NOx Portion
Estimate of Uncetainty < 1% at point #2
0.25%
Assay may be conducted at this concentration
Estimate of Uncetainty < 1% at point #3
0.26%
Assay may be conducted at this concentration
Estimate of Uncetainty < 1% at point #4
0.28%
Assay may be conducted at this concentration

Estimate of Uncetainty < 1% at point #5 (~50% URL
0.31%
Assay may be conducted at this concentration

Analyzer slope is within 0.98-1.02
1.0002
Analyzer Slope is acceptable
Dilution Check
Dilution Check Date within 2 weeks of assay
7-Dec-20
Dilution check within 2 weeks of assay
Dilution Check Relative % Difference < 1%
0.000%
Dilution Check RSD is OK

Day of Assay Zero Check - Std. Error < 1% Std. Error is okay.
Zero Gas Std. Error is OK
Day of Assay Zero/Span Check
NO Portion
Day of Assay Zero Check - Relative Difference < 5°/ RD is okay.
Zero Gas RD is OK
Day of Assay Span Check - Std. Error < 1% Std. Error is okay.
Span Gas Std. Error is OK

Day of Assay Span Check - Relative Difference <5°/ RD is okay.
Span Gas RD is OK


Day of Assay Zero Check - Std. Error < 1% Std. Error is okay.
Zero Gas Std. Error is OK
Day of Assay Zero/Span Check
NOx Portion
Day of Assay Zero Check - Relative Difference < 5°/ RD is okay.
Zero Gas RD is OK
Day of Assay Span Check - Std. Error < 1% Std. Error is okay.
Span Gas Std. Error is OK

Day of Assay Span Check - Relative Difference <5°/ RD is okay.
Span Gas RD is OK
Page 23 of 24

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QA Requirements Summary, Region 7 - 4th Quarter of 2020
OA Requirement	Result	Status

Primary SRM Cylinder Expiration Date
27-Jun-23
Primary SRM Gas Standard OK
SRM Gas Standards
Primary SRM Cylinder Pressure >150 psi
1350
Primary SRM cylinder pressure is OK
SRM Dilution Check Cylinder Expiration Date
5-Apr-22
Dilution Check SRM Gas Standard OK

Dilution Check SRM Cylinder Pressure >150 psi
1625
Dilution check SRM cylinder pressure is OK

High Flow Standard Expiration Date
8-Jan-21
Standard OK
Laboratory Flow Standard
Low Flow Standard Expiration Date
8-Jan-21
Standard OK

Ultra Low Flow Standard Expiration Date
21-Jan-21
Standard OK

Calibrator Flow Calibration within 2 weeks of assay
6-Dec-20
Calibrator flow calibration within 2 weeks of assay
Calibrator (mass flow controllers]
Calibrated High Flow MFC Slope Range = 0.99 - 1.C
0.9999993
High MFC OK

Calibrated Low Flow MFC Slope Range = 0.99 - 1.C
0.9999929
Low MFC OK

Analyzer Calibration within 2 weeks of assay
8-Dec-20
Analyzer calibration within 2 weeks of assay

Estimate of Uncetainty < 1% at point #1 (>80% URL
0.31%
Assay may be conducted at this concentration

Estimate of Uncetainty < 1% at point #2
0.32%
Assay may be conducted at this concentration
Sulfur Dioxide Gas Analyzer
Estimate of Uncetainty < 1% at point #3
0.35%
Assay may be conducted at this concentration

Estimate of Uncetainty < 1% at point #4
0.41%
Assay may be conducted at this concentration

Estimate of Uncetainty < 1% at point #5 (~50% URL
0.74%
Assay may be conducted at this concentration

Analyzer slope is within 0.98-1.02
1.0007
Analyzer Slope is acceptable
Dilution Check
Dilution Check Date within 2 weeks of assay
7-Dec-20
Dilution check within 2 weeks of assay
Dilution Check Relative % Difference < 1%
I
O
o
sP
0s
Dilution Check RSD is OK



Day of Assay Zero/Span Check
Day of Assay Zero Check - Std. Error < 1 % Std. Error is okay.
Day of Assay Zero Check - Relative Difference < 5°/ RD is okay.
Zero Gas Std. Error is OK
Zero Gas RD is OK
Day of Assay Span Check - Std. Error < 1 %
Std. Error is okay.
Span Gas Std. Error is OK

Day of Assay Span Check - Relative Difference <5°/ RD is okay.
Span Gas RD is OK
Page 24 of 24

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United States	Office of Air Quality Planning and Standards	Publication No. EPA-454/R-21-006
Environmental Protection	Air Quality Assessment Division	July 2021
Agency	Research Triangle Park, NC

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