NOx_QAPP_FINAL.pdf

WDEQ-AQD QAPP for NOX/NOY Revision 4.0, November 2025

Title Page

Wyoming Department of Environmental Quality –

Air Quality Division

Quality Assurance Project Plan for Oxides of

Nitrogen/Reactive Oxides of Nitrogen Ambient Air Monitoring Program

November 2025

Revision 4

Section 1

Section A. Project Management

1.0 Quality Assurance Project Plan Identification and Approval

Title: Wyoming Department of Environmental Quality, Air Quality Division (WDEQ-AQD) Quality Assurance Project Plan (QAPP) for the Oxides of Nitrogen/Reactive Oxides of Nitrogen Ambient Air Monitoring Program.

This QAPP for the Oxides of Nitrogen/Reactive Oxides of Nitrogen (NOX/NOY) Ambient Air Quality Monitoring Program is hereby recommended for approval and commits from the Department to follow the elements described within.

Wyoming Department of Environmental Quality – Air Quality Division

Air Pollution Monitoring Program Supervisor, Leif O. Paulson Date

Quality Assurance Coordinator, Ty Hysell Date

Air Pollution Monitoring Program Manager, Mark R. Gagen Date

11/24/2025

11/26/2025

11/24/2025

Section 2

2.0 Table of Contents

Section A. Project Management

1.0 Quality Assurance Project Plan Identification and Approval

2.0 Table of Contents

List of Tables

List of Figures

Acronyms

3.0 Distribution List

4.0 Project/Task Organization

4.1 Air Pollution Monitoring Program Manager

4.2 Air Pollution Monitoring Program Supervisor

4.3 Quality Assurance Coordinator

4.4 Project Managers

4.5 Monitoring Specialists

4.6 Site Operators

4.7 Data Manager

5.0 Problem Definition/Background

5.1 Supporting Documentation

6.0 Project Task Description

6.1 Nitrogen Dioxide Measurements

6.2 Sampling Frequency

6.3 Project Schedule

6.4 Project Reports

7.0 Quality Objectives and Criteria for Measurement of Data

7.1 The DQO Process

7.2 Data Quality Indicators

7.3 Representativeness of the NOx/NOY Measurements

8.0 Special Training/Certifications

9.0 Documents and Records

Section B. Data Generation and Acquisition

10.0 Network Description

11.0 Sampling Method

11.1 NOx/NOY Analyzers

11.2 Support Monitoring Equipment

11.3 Data Acquisition System

11.4 Telecommunications

11.5 Climate-Controlled Shelter

11.6 Zero Air System

11.7 Multi-Gas Dilution Calibrator

11.8 Standard Operating Procedures

12.0 Sample Handling and Custody

13.0 Analytical Method

Section 2

14.0 Quality Control Requirements

14.1 Instrument/Equipment Calibration and Frequency

14.1 Visual Inspection of Equipment

14.2 Remote Interrogation of Monitoring Station and Inspection of Data

14.3 Equipment Calibration

14.4 Calibration Reference Standard Certification

14.5 Zero and Span Checks

14.6 One-point QC Checks

15.0 Equipment Maintenance

16.0 Instrument Equipment Testing, and Inspection

16.1 Acceptance Testing of Instrumentation and Equipment Integration

16.2 Site Surveillance and System Check Procedures

16.3 Site and Equipment Maintenance

17.0 Inspection/Acceptance of Supplies and Consumables

17.1 Spare Parts

17.2 Inspection/Acceptance of Supplies and Consumables

18.0 Non-Direct Measurements

19.0 Data Management

19.1 Data Retrieval

19.2 Raw Data

19.3 Data Transfer

19.4 DAS Data Review

19.5 Data Validation

19.6 Data Transmittal

19.7 Data Processing

19.8 Data Analyses

19.9 Data Flagging

19.10 Data Submittal to AQS

Section C. Assessment and Oversight

20.0 Assessment and Response Actions

20.1 Data Quality Audits

20.2 Corrective Actions

20.3 QAPP Revisions

21.0 Reports to Management

Section D. Data Validation and Usability

22.0 Data Review, Validation, and Verification Requirements

22.1 Data Acceptance Limits for NOx/NOY

23.0 Data Validation and Verification Methods

23.1 Level 0 Data Validation

23.2 Quality Control Checks for Data Validation

23.3 Level 1 Data Validation

23.4 Minimum Acceptable Data Recovery Percentage

Section 2

23.5 Data Report QA Checklist

24.0 Reconciliation with User Requirements

References

APPENDIX A: Standard Operating Procedures

Appendix A.1 - Standard Operating Procedures for NOX and NOY Analyzers

Appendix A.2 Standard Operating Procedure for Performance Evaluations of Gaseous Analyzers

APPENDIX B: Ancillary Information

APPENDIX C: Revision Summary

Section 2

List of Tables

Table 1. QAPP Distribution List Table 2. NO2 NAAQS and WAAQS Averaging Time, Levels, and Form Table 3. Project Reports Table 4. DQO Seven-Step Decision Tree Process Table 5. Documents and Reports Table 6. NOX/NOY Analyzer QC Procedures Table 7. Critical Criteria for NOX/NOY Analyzers Table 8. Operational Criteria for NOX/NOY Analyzers Table 9. Systematic Criteria for NOX/NOY Analyzers Table 10. Systematic Criteria for NOX/NOY Analyzers Support Equipment Table 11. Site Maintenance Activities Table 12. Equipment Maintenance Activities Table 13. NO2 Audit Levels Table 14. Reports to Management Table 15. Data Flags

List of Figures

Figure 1. WDEQ-AQD Organizational Chart Figure 2. WDEQ-AQD NO2 Monitoring Site Locations, 1998-2025 Figure 3. Illustration of the NOY Inlet and Molycon Protective Housing Figure 4. Configuration of Monitoring Equipment in the Instrument Rack

Section 2

Acronyms

AGL Above Ground Level AMTIC Ambient Monitoring Technology Information Center APE Annual Performance Evaluations APMP Air Pollution Monitoring Program APTI Air Pollution Training Institute AQD Air Quality Division AQS Air Quality System ASQ American Society for Quality AWMA Air & Waste Management Association CFR Code of Federal Regulations

DAS Data Acquisition System DQIs Data Quality Indicators DQOs Data Quality Objectives E-log Electronic Logbook EPA U.S. Environmental Protection Agency FRM Federal Reference Method GPT Gas Phase Titration HVAC Heating, Ventilation, and Air Conditioning IMPACT Inventory, Monitoring, Permitting, And Compliance Tracking system IMS Industrial Monitoring Stations

IP Internet Protocol IR Infrared MFC Mass Flow Calibrator MQOs Measurement Quality Objectives NAAQS National Ambient Air Quality Standards NPAP National Performance Audit Program NIST National Institute of Standards and Technology NCore National Core Air Measurement Network NO Nitric Oxide NO2 Nitrogen Dioxide NOX Oxides of Nitrogen NOY Total Reactive Oxides of Nitrogen NOZ Reactive Oxides of Nitrogen OAQPS Office of Air Quality Planning and Standards PAN Peroxyacetyl nitrate PEs Performance Evaluations

PEP Performance Evaluation Program PFA Perfluoroalkoxy alkane PMT Photomultiplier Tube PQAO Primary Quality Assurance Organization PTFE Polytetrafluoroethylene QA Quality Assurance QAPP Quality Assurance Project Plan QC Quality Control QMP Quality Management Plan

SLAMS State and Local Air Monitoring Stations

SLT State/Local/Tribal SOP Standard Operating Procedure SPMS Special Purpose Monitoring Stations

Section 2

TTP Through-the-Probe WAAQS Wyoming Ambient Air Quality Standards WDEQ Wyoming Department of Environmental Quality

Section 3

3.0 Distribution List

The following individuals listed in Table 1 have been provided a copy of this Quality Assurance Project Plan (QAPP).

Table 1. QAPP Distribution List

Wyoming Department of Environmental Quality, Air Quality Division

Name Position

Amber Potts Administrator

Mark Gagen Air Pollution Monitoring Program Manager

Leif Paulson Air Pollution Monitoring Program Supervisor

Ty Hysell Quality Assurance Coordinator

Jacob Berreth CEMS/SLAMS Coordinator

Lauren Deverse Exceptional Events Analyst/Project Manager

Ardyss Thai Data Manager

Jack Kokkinen Project Manager

Grayson Rotter Project Manager

Jackson Sansone Project Manager

Paul Bailey Monitoring Specialist

Trevor Hale Monitoring Specialist

EPA Region VIII

Name Position

Joshua Rickard Wyoming Monitoring Contact

YeChan Lim Supervisor, Monitoring and Program Support Section

Section 4

4.0 Project/Task Organization

Since the early 1970s, the Air Pollution Monitoring Program (APMP) has been committed to monitoring the air quality of Wyoming with the goal of protecting, conserving, and enhancing the quality of Wyoming’s environment for the benefit of current and future generations. The APMP provides the WDEQ-AQD with valuable information that allows for the determination of future policy considerations.

The WDEQ-AQD plans, operates, and maintains several different types of ambient monitoring stations, including a National Core air monitoring network (NCore) station, State and Local Air Monitoring Stations (SLAMS), Special Purpose Monitoring Stations (SPMS), Interagency Monitoring of Protected Visual Environment (IMPROVE) monitoring stations, and Industrial Monitoring Stations (IMS).

The SLAMS are sited in populated areas to monitor public health and demonstrate compliance with the National Ambient Air Quality Standards (NAAQS) but may serve other purposes, such as:

• Providing air pollution data to the general public in a timely manner

• Supporting compliance with air quality standards and emissions strategy development

• Supporting air pollution research studies

The SPMS collectively have multiple objectives. These objectives include:

• Providing air pollution data to the general public in a timely manner

• Monitoring public health

• Investigating pollutant concentrations downwind of sources

• Determining background pollutant concentrations

Since 2011, the WDEQ-AQD has operated a fleet of mobile monitoring stations (“mobile stations”) to investigate questions or concerns about air quality on a short-term basis (typically one year).

Additionally, the WDEQ-AQD administers an NCore station as part of the national network to evaluate long-term trends in air quality. The IMS are independently operated stations that meet the requirements of their permits. Although WDEQ-AQD has oversight authority for the permit-required monitoring networks, the IMS operate as independent Primary Quality Assurance Organizations (PQAOs).

The WDEQ-AQD is committed to quality and the implementation of the procedures and practices found in this QAPP. Quality assurance (QA) is an integrated system of management activities involving planning, implementation, assessment, reporting, and quality improvement to ensure that a process, item, or service is of the type and quality needed and as expected. Quality control (QC) is the overall system of technical activities that measures the attributes and performance of a process, item, or service against defined standards to verify that they meet the stated requirements established by the customer. The QC system includes the operational techniques and activities that are used to fulfill requirements for quality.

Quality control is largely implemented through the QAPP and the standard operating procedures (SOPs). Each instrument in the various monitoring programs have unique requirements, statutory standards, and support equipment that must be in place for the instrumentation to be operated according to the guidelines, rules, and policies that must be followed. This QAPP incorporates the unique qualities that are specific to nitrogen dioxide and reactive oxides of nitrogen species within the WDEQ-AQD monitoring network.

Section 4

Implementation of the WDEQ-AQD monitoring program requires an investment by the entire management team up to the Air Pollution Monitoring Program Manager. WDEQ-AQD management recognizes and accepts this responsibility to identify the QA requirements that will meet the needs and expectations of the monitoring program. Any worthwhile monitoring program focuses on preventing quality problems.

Since the WDEQ has an overarching Quality Management Plan (QMP) in place, this and all QAPPs will be mandated by the WDEQ QMP. The QMP describes the quality system in terms of the organizational structure, functional responsibilities of management and staff, lines of authority, and required interfaces for those planning, implementing, assessing, and reporting activities involving environmental data operations.

The following subsections describe the project participants and roles and the responsibilities of each participant. Figure 1, which is in the last portion of this section, illustrates that management structure.

4.1 Air Pollution Monitoring Program Manager

The APMP Manager has overall responsibility for managing the WDEQ-AQD according to WDEQ policy and the direct responsibility for assuring data quality rests with line management. Ultimately, the APMP Manager is responsible for establishing QA policy and for resolving QA issues identified through the QA program.

Major QA related responsibilities of the APMP Manager include:

● Participating in the budget and planning processes.

● Assuring that the WDEQ-AQD develops and maintains a current and germane quality system.

● Assuring that the WDEQ-AQD develops and maintains current QAPPs.

● Assuring adherence to the QA documents by staff and, where appropriate, other extramural cooperators establishing policies to ensure that QA requirements are incorporated in all environmental data operations.

● Maintaining an active line of communication with the Monitoring Supervisor, QA Coordinator, and Project Managers conducting management systems reviews.

The WDEQ-AQD APMP Manager delegates the responsibility of QA development and implementation in accordance with WDEQ-AQD policies. Oversight of the WDEQ-AQD's QA program is delegated to the Quality Assurance Coordinator.

4.2 Air Pollution Monitoring Program Supervisor

The WDEQ-AQD Monitoring Supervisor is the delegated manager of the routine monitoring programs, which includes the QA/QC activities that are implemented as part of normal data collection activities.

Responsibilities of the APMP Supervisor include:

• Communicating with EPA Project Officers and QA Personnel regarding sampling and QA activities.

• Understanding EPA monitoring and QA regulations and guidance to ensure subordinates understand and follow the regulations and guidance.

• Understanding the WDEQ-AQD's QA policy and ensuring subordinates do as well.

• Understanding and ensuring adherence to the QAPP.

Section 4

• Reviewing acquisition packages (contracts, grants, cooperative agreements, and interagency agreements) to determine the necessary QA requirements.

• Developing budgets and providing program costs necessary for EPA allocation activities.

• Ensuring that all personnel involved in environmental data collection have access to any training or QA information needed to be knowledgeable in QA requirements, protocols, and technology.

• Certifying to EPA that data are true, correct, and reported to EPA per Title 40 Code of Federal Regulations (CFR) Part 58.151.

4.3 Quality Assurance Coordinator

The QA Coordinator is the delegated manager of the WDEQ-AQD's QA Program. The QA Coordinator has direct access to the Administrator, APMP Manager and APMP Supervisor on all matters pertaining to QA. The QA Coordinator’s main responsibility is QA oversight and ensuring that all personnel understand the WDEQ-AQD's QA policy and all pertinent EPA QA policies and regulations specific to the APMP. The QA Coordinator provides technical support and reviews and approves QA products. Responsibilities include:

● Developing and interpreting WDEQ-AQD QA policy and revising it as necessary.

● Developing a QA Annual Report for the Administrator.

● Assisting Monitoring Specialists and Project Managers in developing QA documentation and in providing answers to technical questions.

● Ensuring that all personnel involved in environmental data operations have access to any training or QA information needed to be knowledgeable in QA requirements, protocols, and technology.

● Ensuring that environmental data operations are covered by appropriate QA planning documentation (e.g., QAPPs, data quality objectives, etc.).

● Ensuring that reviews, assessments, performance evaluations, and audits are scheduled and completed and, if needed, conducting or participating in QA activities.

● Tracking the QA/QC status of all programs.

● Recommending required management-level corrective actions.

● Serving as the program's QA liaison with EPA Regional QA Managers or QA Officers and the

Regional Project Officer.

● Uploads Quality Assurance data to EPA’s AQS System.

The QA Coordinator has the authority to carry out these responsibilities and to bring to the attention of the APMP Manager any issues associated with these responsibilities. The QA Coordinator either performs or delegates the responsibility of QA development and implementation.

Section 4

4.4 Project Managers

Project Managers are responsible for project coordination; oversight of the contractor activities;

maintaining the official, approved QAPP; and QAPP distribution. Responsibilities include:

• Ensuring the day-to-day operation and upkeep of all monitors are maintained.

• Overseeing data processing, reporting, and assuring data collection is performed in a timely fashion.

• Understanding EPA monitoring, QA regulations and guidance, and ensuring the Contractors, Monitoring Specialists and Site Operators understand and follow those standards.

• Understanding WDEQ-AQD QA policy and ensuring subordinates understand and follow the policy.

• Understanding and ensuring adherence to the QAPP as it relates to program support activities.

• Participating in the development of data quality requirements with the appropriate QA staff.

• Writing and modifying QAPPs and SOPs.

• Verifying that all required QA activities were performed and quality standards were met as required in the QAPP.

4.5 Monitoring Specialists

The WDEQ-AQD field personnel are responsible for carrying out required tasks and ensuring the data quality results of the tasks by adhering to the guidelines and protocols specified by the QAPP and SOPs for the field activities. Responsibilities include:

• Participating in the implementation of standards, as laid out in the QAPP.

• Keeping up-to-date in training and certification activities.

• Verifying that all required QA activities are performed and quality standards are met (as required by the QAPP).

• Following manufacturer specifications for any equipment used.

• Documenting deviations from established procedures and methods.

• Reporting all problems and corrective actions to the Contractor and Project Manager.

• Preparing and delivering reports to the Project Manager.

• Assessing and reporting on data quality.

4.6 Site Operators

The Site Operators visit the monitoring stations once a month. The Site Operator’s role is to do routine maintenance on the monitoring station and instrumentation. For the purpose of this NOX/NOY QAPP (and other gaseous parameters), the WDEQ-AQD Monitoring Specialist can perform the duties of the Site Operator. Responsibilities include:

• Change in-line filters on the continuous instruments (monthly).

• Perform unexpected tasks such as running a manual calibration (if necessary after a repair).

• Replace electronic or pneumatic components at the direction of a Contractor or Project

Manager.

• Reporting all problems and corrective actions to the Contractor and Project Manager.

• Thoroughly documents all activities performed at a station and reports activities and results to the Contractor and Project Manager.

• Assessing and reporting on data quality.

Section 4

4.7 Data Manager

The Data Manager reports to the Air Pollution Monitoring Program Manager and is in charge of the WyVisNet website and the AirVision data management system, which runs WyVisNet. Responsibilities include:

• The Data Manager is in charge of uploading data to the EPA’s Air Quality System (AQS), which is the National database for all air pollution and meteorological data.

• Ensures data are moved to/from the IMPACT system and shared drives per the WDEQ Records Management Plan.

• Performs data queries within the central database in Cheyenne headquarters.

• Works with the vendors that supply and maintain the WyVisNet software system.

• Performs data analyses as described in Sections 22 and 23 of this QAPP.

Please note that an annual review of the QAPP will be performed and, if no changes are needed, the WDEQ-AQD will document that no changes were necessary. If changes are required, revised pages with the revisions will be inserted/changed, revisions will be tracked, and a new revision number will be assigned to the document.

Section 4

Figure 1 illustrates the organizational structure for the WDEQ-AQD. For a list of project participants, please see Appendix B.

Figure 1. WDEQ-AQD Organizational Chart

Section 5

5.0 Problem Definition/Background

This QAPP pertains strictly to the collection and analysis of NOX or NOY within the WDEQ-AQD monitoring network and details the methodologies to establish precise and accurate NOX/NOY measurements at all stations within the WDEQ-AQD monitoring network, regardless of the type of monitoring that is performed.

The objective of the monitoring network is to provide the necessary information for developing a representative air quality data set capable of delineating differences among geographical and climatological regions. The monitored data are used to characterize and monitor trends in air quality and air quality standards’ compliance and may be used for national health assessments, model evaluations, and comparison with other ambient air monitoring data. The procedures outlined in this QAPP have been developed to meet the goals and objectives of the monitoring project. Revisions to the QAPP are made, as necessary, to reflect changes to the regulations or goals of the monitoring project. As a minimum, the QAPP is reviewed annually and revisions are made as necessary on an annual basis.

Every year the WDEQ-AQD publishes an Annual Network Plan1, which discusses the monitoring operations for each station in Wyoming, including all the monitoring stations that will monitor for NOX/NOY parameters. Every five (5) years, a Network Assessment is published by the WDEQ-AQD, which discusses in detail the status of the monitoring stations and the need for additional monitoring. The stations at which the WDEQ-AQD currently operates NOX/NOY analyzers are listed in Appendix B, Instrument Locations.

The NAAQS one-hour primary standard is met when a one-hour average of Nitrogen Dioxide (NO2) exceeds 100 ppb or exceeds an annual mean of 53 ppb (see Table 2). At the writing of this QAPP, no stations within the State of Wyoming were considered in Non-Attainment. Please note, that the Cheyenne NCore station and Boulder station each have one NOY analyzer in addition to NOX analyzers.

All other stations have NOX analyzers only. The distinctions between NOY and NOX analyzers will be discussed in Section 15.

Table 2. NO2 NAAQS and WAAQS Averaging Time, Levels, and Form

Pollutant Primary/Secondary Averaging Time Level Form

NO2

Primary 1-hour 100 ppb

98th percentile of 1-hour daily maximum concentrations averaged over 3 years

Primary and Secondary Annual 53 ppb Annual Mean

Below is Figure 2, which illustrates the WDEQ-AQD Monitoring Stations, both past and present. As it can be seen from this map, the WDEQ-AQD monitoring network covers the entire State.

Section 5

Figure 2. WDEQ-AQD NO2 Monitoring Site Locations, 1998-2025

5.1 Supporting Documentation

The information collected for this monitoring program will meet the requirements as found in the following documents:

• 40 CFR Part 58, Appendices A-E2

• 40 CFR Part 50, Appendix F3

• Quality Assurance Handbook for Air Pollution Measurement Systems, Volume II: Ambient Air Quality Monitoring Program, EPA‐454/B‐17‐001, January 20174

• Technical Assistance Document (TAD) for Precursor Gas Measurements in the NCore Multi- Pollutant Monitoring Network, Version 4, EPA-454/R-05-003, September 20055

• Quality Assurance Handbook for Air Pollution Measurement Systems, Volume I: A Field Guide to Environmental Quality Assurance EPA- 600/R-94/038a, April 19946

• Technical Assistance Document for Sampling and Analysis of Ozone Precursors for the Photochemical Assessment Monitoring Stations Program, EPA Document EPA-454/B-19-004, April 20197

• Technical Assistance Document for Sampling and Analysis of Ozone Precursors for the Photochemical Assessment Monitoring Stations Program, EPA Document EPA-454/R-23-002, May

Section 5

20237

The guidance presented in the above-listed documents will be followed for this monitoring program and is intended to ensure that the data collected and technical information are documented and of appropriate quality and usability.

Section 6

6.0 Project Task Description

6.1 Nitrogen Dioxide Measurements

Oxides of nitrogen are released from emission sources primarily as nitric oxide (NO) and to a lesser extent as nitrogen dioxide (NO2). The two species are collectively termed NOX (NOX = NO+ NO2).

Through atmospheric processes, NOX is converted to many other inorganic and organic nitrogen oxides, such as:

• nitrous acid (HONO);

• nitric acid (HNO3);

• peroxyacetyl nitrate (H3CC(O)OONO2, or PAN).

Collectively, these three species are known as NOZ. Therefore, the total of all reactive nitrogen species is NOY, which the EPA recognizes as the sum of NOX and NOZ (i.e., NOY = NOX + NOZ).

In addition to NO2 being a criteria pollutant in the NAAQS and WAAQS, it also plays a critical role in the photochemical production of ozone. Accurate measurement of NO2 concentrations in ambient air is necessary to support air quality modeling efforts aimed at evaluating and tracking the progress of control strategies for attaining the ozone NAAQS.

6.2 Sampling Frequency

Data from the NOX/NOY analyzers are sampled every second by the Data Acquisition System (DAS). The DAS then stores the data in 1-minute and hourly average increments (at a minimum). This data is then transmitted and reviewed by WDEQ-AQD and the Contractors on a defined interval at their central location.

6.3 Project Schedule

Personnel working on this project are fully qualified, trained, and capable to perform their assigned duties. Work schedules include: daily data review, quarterly and semi-annual air quality equipment calibrations, quarterly data summaries within sixty (60) days of quarter completion, annual reports within ninety (90) days of year completion, and maintenance and corrective action.

Section 6

6.4 Project Reports

Table 3 presents the reports that will be produced as part of this project.

Table 3. Project Reports

Reports Frequency Content Responsible Position

Quarterly Data Reports Quarterly

Summarizes data following EPA guidelines, including accuracy and precision

Contractor with review by Project Manager

Annual Data Report Annually Summarizes data following EPA guidelines

Contractor with review by Project Manager

Performance Audit Reports*

Semi‐annually Summarizes audit results following EPA guidelines

WDEQ‐AQD QA

Coordinator or

Contractor with review by Project Manager

Corrective Action Reports

As Needed

Summarizes corrective actions taken to return the monitoring station to compliant status

Contractor with review by Project Manager

Response to Corrective Action Reports

As Needed Reports the results of the corrective actions taken

Contractor with review by Project Manager

*Boulder and Cheyenne NCore are audited quarterly.

Section 7

7.0 Quality Objectives and Criteria for Measurement of Data

This section discusses the Data Quality Objectives (DQOs), Measurement Quality Objectives (MQOs) and Data Quality Indicators (DQIs) that are mandatory for all monitoring programs.

Generally, the DQOs for any program are created by the stakeholders. The DQO process is a seven-step decision tree that allows the stakeholders of the WDEQ-AQD to define parameters for the program. The DQO process has been in existence for many years, first by the EPA and then utilized by the State, Local and Tribal governments that are required to collect data on behalf of the EPA. Please note that it is outside of the scope of this document to discuss whether or not the State of Wyoming, or parts of the state, are in attainment. Please refer to the WDEQ-AQD Annual Network Plan 20251 for the discussion of attainment for Nitrogen Dioxide. In addition, please note that of all of the NOX/NOY species, only NO2 has a NAAQS/WAAQS attainment status.

As mentioned before, the DQO is a seven-step process that takes the form of a discussion of the important aspects of the program. It is encouraged and useful that the DQO process is performed from time to time to ensure that the objectives are clear and concise.

7.1 The DQO Process

On August 12, 2020, the WDEQ-ADQ and its Contractor met to discuss the DQOs for the programs and define the objectives. Table 4 below outlines the discussion and the outputs of the DQO process in each step.

In order for the DQOs to be fulfilled, MQOs are designed to evaluate and control various phases (sampling, preparation, and analysis) of the measurement process to ensure that total measurement uncertainty is within the range prescribed by the DQOs. MQOs can be defined in terms of the following DQIs: precision, bias, representativeness, detectability, completeness, and comparability.

Table 4. DQO Seven-Step Decision Tree Process

DQO Step Output to Discussion by Decision Makers

Step 1. State the Problem

The State of Wyoming, being within the bounds of the United States, must adhere to the Clean Air Act Amendments. The Code of Federal

Regulations 40 part 50 set the NAAQS and the State of Wyoming measures for the NAAQS pollutants. In addition, the State of

Wyoming promulgated its own Ambient Air Quality Standards (WAAQS), which are identical to the NAAQS. The State of Wyoming must comply with these standards and thus measure in various locations to meet the requirements. In addition, EPA requires that each state must operate a National Core (NCore) monitoring station and one of the requirements for an NCore monitoring station is to operate an NOY analyzer.

Step 2. Identify the Goal of the Study

Not only does the State of Wyoming have to measure for NO2

NAAQS pollutants, but it must also adhere to the level of the standard (attainment vs. non-attainment as promulgated in 40

CFR Part 50). An additional goal for this network is to understand the reactivity of the atmosphere in urban areas. This is the reason for the NOY monitoring at the NCore monitoring station in the metropolitan area of Cheyenne.

Step 3. Identify the Information Input

The input information is the hourly average data that is collected at the locations where NOX/NOY are monitored.

Section 7

DQO Step Output to Discussion by Decision Makers

Step 4. Define the Boundaries of the Study

The boundary of the study is the entire State of Wyoming. Within the State, there are two Primary Quality Assurance Organizations

(PQAOs). The two divisions of PQAOs are the WDEQ-AQD and the independent industrial monitoring PQAOs.

Step 5. Develop the Analytical Approach

The WDEQ-AQD will collect NOX/NOY data at the monitoring locations stated in Appendix B. At the end of the year, the WDEQ-

AQD will review, analyze and certify that the data collected within the WDEQ-AQD network are valid within the parameters as laid out in this QAPP.

Step 6. Specify Performance Criteria

The performance criteria are described in this QAPP under the MQOs and thus the DQIs. If the data collected adhere to these performance criteria, then the data can be used to ascertain if the State of Wyoming is within non-attainment or attainment status. The results of the decisions on attainment are discussed in detail within the WDEQ-AQD Annual Network

Plan1.

Step 7. Develop the Plan for Obtaining Data

Having developed these DQOs, the WDEQ-AQD has developed this NOX/NOY QAPP and SOP to ensure that the QA and QC procedures are documented and followed by WDEQ-AQD staff and their Contractors.

Section 7

7.2 Data Quality Indicators

The data quality indicators (DQIs) are a set of indicators that can be easily measured. For instance, precision and bias can be calculated using statistical methods on the data. The other DQIs are either inherent in the NOX/NOY analyzers, i.e. detection limits, or indicate how the samples are handled and analyzed.

Here is a discussion of each DQI:

• Precision - a measure of agreement among repeated measurements of the same property under identical, or substantially similar, conditions. This is the random component of error. Precision is estimated by various statistical techniques typically using some derivation of the standard deviation. For NOX/NOY, precision is determined based on the three-day zero, span, and precision checks.

• Bias - the systematic or persistent distortion of a measurement process that causes error in one direction. Bias will be determined by estimating the positive and negative deviation from the true value. Bias is determined by using the paired data from the 1-in-3 day QC checks.

• Detection Limit - the lowest concentration or amount of the target analytic that can be determined to be different from zero by a single measurement at a stated level of probability.

For the high- sensitivity instruments, this is an important DQI. The EPA specifies how and how often this test is performed, which is recommended annually. The specific procedures are detailed in the SOP for NOX/NOY analyzers, which is a companion document to this QAPP.

• Completeness - the amount of valid data obtained from a measurement system compared to the amount that was expected to be obtained under normal conditions. Data completeness requirements are discussed in NAAQS (40 CFR Part 50)3.

• Comparability - generally falls under the auspice of equipment specifications and monitoring methods. For the example of NOX, only Federal Reference Method (FRM) analyzers are used for data collection. The methodology used is to draw the air samples into the analyzer using federally approved glassware and Teflon tubing.

• Representativeness- this DQI deals with whether or not the location of the NOX/NOY analyzer represents the type of monitoring that is necessary, i.e., is the station sited appropriately for the objective.

• Accuracy - a measure of the overall agreement of a measurement to a known value, including a combination of random error (precision) and systematic error (bias) components of sampling. This is performed using annual performance evaluations (APEs). In addition, the EPA or its designee will also perform through-the-probe (TTP) audits (as part of the National Performance Audit Program (NPAP)). These QA procedures are discussed in more detail in Section 20 of this QAPP.

For NOX/NOY measurements, the goal for acceptable measurement uncertainty (precision) is an upper 90 percent confidence limit for the coefficient variation (CV) of <10.0 percent (%). The bias for NOX/NOY is expressed as an upper 95% confidence limit for the absolute bias of <10.0%.

Section 7

7.3 Representativeness of the NOx/NOY Measurements

Site selection and probe placement follow guidelines in the following US EPA documents to assure that measurements are representative of meteorological and air quality monitoring conditions near the monitoring station:

• Quality Assurance Handbook for Air Pollution Measurement Systems, Volume I: A Field Guide to Environmental Quality Assurance 19946

• Quality Assurance Handbook for Air Pollution Measurement Systems, Volume II: Ambient Air Quality Monitoring Program, EPA-454/B-17-001, January 20174

• 40 CFR 58, Appendices A, C, and E2

• Technical Assistance Document for Precursor Gas Measurements in the NCore Multi- Pollutant Monitoring Network, Version 4, EPA-454/R-05-003 September 20055

The monitoring sites that were selected to house the NOX/NOY analyzers were selected to be as representative as possible of the general region of interest. The placement of a shelter considers local interferences, distance to structures, trees, and roadways, and the height of the probe above ground. The network was set up in accordance with EPA-defined ambient air quality siting criteria.

Section 8

8.0 Special Training/Certifications

Personnel assigned to the ambient air monitoring programs will meet the educational, work experience, responsibility, and training requirements for their positions. Records on personnel qualifications and training will be maintained in personnel files and will be accessible for review during audit activities. All WDEQ-AQD staff will follow the APMP’s training plan and provide proper documentation and tracking.

Adequate education and training are integral to any monitoring program that strives for reliable and comparable data. It is recommended that WDEQ-AQD maintains some requirements for personnel qualifications (combination of education and experience). Training is aimed at increasing the effectiveness of employees and their organization.

As part of a quality assurance program, the procedures should include information on:

• Personnel qualifications (general and position-specific)

• Training requirements (based on position)

• Frequency of training

Appropriate training should be available to employees supporting the Ambient Air Quality Monitoring Program and commensurate with their duties. Such training may consist of classroom lectures, workshops, web-based courses, teleconferences, vendor-provided and on-the-job training. Training should also include appropriate reading materials, such as the CFR, EPA guidance documents, and the WDEQ-AQD’s QAPPs and SOPs, to name a few.

EPA encourages monitoring organizations to maintain documentation that details the training provided to all monitoring staff, along with documentation that illustrates the successful completion of the training requirements. Along with suggested training, some EPA programs require mandatory training and/or certifications. These programs include, but are not limited to, the National Performance Audit Program (NPAP) and the Performance Evaluation Program (PEP). All personnel performing audits in these projects or programs are required to possess mandatory training or a current certification issued by the EPA Office responsible for the monitoring program. EPA encourages regional planning organizations and monitoring organizations to develop training programs that require some level of certification. Over the years, several courses have been developed for personnel involved with ambient air monitoring and quality assurance aspects.

Formal QA/QC training is offered through the following organizations:

• AirKnowledge https://airknowledge.gov/

• Air & Waste Management Association (AWMA) https://www.awma.org/

• American Society for Quality (ASQ) https://asq.org/

• EPA Quality Program https://www.epa.gov/quality

• EPA Regional Offices https://www.epa.gov/aboutepa/regional-and-geographic-offices

• EPA Ambient Monitoring Technology Information Center (AMTIC) Technology Transfer Network https://www.epa.gov/amtic

Section 8

WDEQ-AQD should consider adding manufacturer-provided training to the equipment purchase cost.

Personnel having experience in the subject matter described in the courses would select courses according to their appropriate experience level. Courses not included in the core sequence would be selected according to individual responsibilities, preferences, and available resources.

Section 9

9.0 Documents and Records

The WDEQ-AQD is committed to fully documenting all activities related to data collection, analysis, validation, and reporting. Table 5 contains a list of the records maintained by the WDEQ-AQD monitoring program. These records can be electronic, bound in notebooks, and/or forms that are used for specific applications. Electronic records will be stored on main office storage drives and archived by the Contractors and ultimately, the WDEQ-AQD office servers. All project files are backed up daily. In addition, weekly network backup occurs. The weekly backup network files are stored on external hard drives which are stored off-site. The WDEQ-AQD has several of these backup hard drives and copies of the field logbook are archived in the WDEQ-AQD Cheyenne office for five (5) years.

Table 5. Documents and Reports

Documentation Type

Frequency Report

Submission Archive Retention Period

Monitoring Data Daily Downloads Contractors

WDEQ‐AQD and Contractor’s Server (with backup)

5 years

QAPP and SOPs Annually or more frequently, as needed

QA Coordinator WDEQ‐AQD 5 years

Copies of Field Logbooks

After each site visit

Site Operators and Contractors

WDEQ‐AQD and Contractors

5 years

Quarterly Reports Quarterly Contractors WDEQ‐AQD and

Contractors 5 years

Annual Data Report

Annually Contractors WDEQ‐AQD and

Contractors 5 years

Performance Audit Summaries

Semi‐Annually QA Coordinator or

Contractor WDEQ‐AQD 5 years

All monitoring data, reports and program documentation will be retained by the WDEQ-AQD for a minimum of five (5) years. The WDEQ-AQD will review and approve changes to the QAPP given updates or changes to the Records Management Plan.

Section 10

Section B. Data Generation and Acquisition

10.0 Network Description

This section describes the project design and implementation of the NOX/NOY monitoring network.

For the list of current locations and a description of the NOX/NOY monitoring network, please see Section 1.0 of Appendix B, Instrument Locations.

Section 11

11.0 Sampling Method

NOX/NOY photometry is a spectrophotometric method that has been used since the early 1980s and is the preferred method for measuring oxides of nitrogen species, whether reactive or not.

NOX and NOY analyzers work primarily in the same manner, nitric oxide (NO) is shunted into a chamber with ozone and the following reaction occurs:

NO + O3 → NO2 + O2 + 1 photon

Next to the reaction chamber is a highly sensitive photomultiplier tube (PMT). The PMT is able to convert the photon to an electron. The circuitry within the analyzer counts the number of electrons captured and converts that to a current that is directly related to the concentration of NO in the chamber. The main difference between the NOX and NOY analyzer is that the NOY analyzer has an external molybdenum converter (Molycon) that converts all NOZ species to NO. The NOX analyzer has an internal Molycon and converts NOX species to NO. By integrating a solenoid valve switching system, the analyzer measures NO in one cycle and NOX/NOY in the other. The analyzer records the data internally and communicates that information to the DAS.

NO is a stable gas that can be stored in compressed aluminum cylinders. Because of this, cylinders can be filled with known concentrations of NO and shipped to any location. The NO concentrations, if high enough, can be stable in the cylinders for many years. Several gas vendors lease or sell cylinders that are traceable to the National Institute of Standards and Technology (NIST) traceable standards for NO. In this manner, cylinders can be leased of known concentrations and taken to the ambient air monitoring locations throughout the State of Wyoming. If properly stored and utilized, cylinders can be used to calibrate, verify or audit the instruments in the field. Please note that gas cylinders must be stored safely and requires strapping or chaining the cylinder in a vertical position to a wall or secured fastened bench.

The NOX/NOY analyzers operated by the WDEQ-AQD are placed in monitoring shelters across the state. The samples are drawn into the instrument as described in the Quality Assurance Handbook for Air Pollution Measurement Systems: Volume II4 and Technical Assistance Document for Precursor Gas Measurements in the NCore Multi-Pollutant Monitoring Netwrok5. NOX is measured by sampling ambient air from either a borosilicate glass manifold or sample lines that are made of PTFE or PFA Teflon. For NOx measurements, the sampling inlet is on the roof of the shelter approximately four (4) meters above ground level (AGL). The Teflon sampling line or glass manifold is protected by a pipe with a Teflon-coated cover protecting the inlet probe. A Teflon particulate filter also protects the sampling line.

For NOX instruments, the Teflon Inlet line is connected to a borosilicate glass manifold. The NOX analyzer uses a Teflon line to connect to a port on the manifold. A pump is connected to the end of the manifold to keep the residence time as low as possible. The residence time of the analyzers will be maintained at less than twenty (20) second residence time requirement. NOX/NOY probe siting information and site configuration for the monitoring is in accordance with 40 CFR Part 58 Appendix E2.

Because the NOZ species that exist in the atmosphere are so reactive, the species must be converted to NO before they enter the monitoring station. As mentioned earlier, the Molycon is mounted externally on top of a 10-meter tower.

Section 11

Figure 3. Illustration of the NOY Inlet and Molycon Protective Housing

11.1 NOx/NOY Analyzers

For a list of the current analyzers utilized throughout the WDEQ-AQD monitoring network, please see Appendix B, Types of Instruments.

11.2 Support Monitoring Equipment

The operating range of the analyzers easily brackets the range of environmental conditions expected at the site. The SOP for NOX/NOY analyzers details the calibration and operation of the equipment.

The supporting equipment used at the monitoring stations are discussed in the following sections.

11.3 Data Acquisition System

Instantaneous data from the NOX/NOY analyzers are transferred once per second to the DAS usually by a serial cable. The DAS is a self-contained box with the ability to measure and control electronics and communicate with on-site computers or remote systems. Data is generally stored in a table format.

Please note that the DAS stores 1-minute and hourly data (at a minimum). The one-second data is not stored. In addition, the DAS communicates with the multi-gas dilution calibrator and initiates automated zero, precision and span checks. The DAS records the response to the checks and then can compare that response to the expected value.

11.4 Telecommunications

Telecommunication services are used for high-speed remote communication to all on-site equipment, including the DAS. Additionally, each analyzer on-site is configured with a unique internet protocol (IP) address for remote maintenance and control purposes. The gateway has all of the firewall protection and routing protocols necessary for protection, isolation, and security.

Section 11

11.5 Climate-Controlled Shelter

The shelter temperature is maintained by a heating, ventilating, air conditioning (HVAC) system. The temperature is controlled by a thermostat located within the shelter. The temperature is maintained at 20-30 °C at all times. The shelter houses the analyzers, calibration equipment, sample intake manifold, DAS and cylinders.

11.6 Zero Air System

In order to determine the baseline of the analyzer and its detection limit, a zero air system is used.

The zero air system is a fully self-contained source of high purity zero air for dilution calibrators. It is ideal for use with highly sensitive analyzers in ambient background and trace level applications. The zero air system includes a dew point sensor, an oil and diaphragm-free pump, and scrubbers to remove all pollutants measured.

The regenerative, heatless dryer removes water and produces output with a dew point less than - 40°C (up to a flow rate of 30 standard liters per minute (SLPM)). The system's pressure, temperature, and dew point values are all continuously monitored, which allows a microcontroller to adjust the pump cycling frequency, valve timing, and heater power for optimal performance. The WDEQ-AQD Contractors will perform an annual zero air test. This is performed by substituting the zero air generator with a compressed gas zero air cylinder from a verified gas vendor. The gas cylinder is hooked up to the Mass Flow Controller unit and all analyzers are allowed to sample the zero air from the cylinder. The zero response of the NOX/NOY analyzer is then compared to the zero air response from the zero air generator.

11.7 Multi-Gas Dilution Calibrator

The multi-gas dilution calibrator is an integrated gas flow controlling device that contains mass flow controllers (MFCs) that can flow and mix pressurized gases and zero air in very precise and accurate amounts to be shunted to the analyzers. A high pressure cylinder with a known concentration of NO gas flows from the cylinder and is shunted through a solenoid valve. This gas is then mixed with “zero air”, i.e., air that has less than 1.0 part per billion (ppb) of NO or NO2 in a mixing chamber. For the trace level analyzers, the zero air must contain less than 50 parts per trillion (ppt). Once the zero air and NO are mixed, it is allowed to enter the station manifold. The analyzer draws in the gas and measures the concentration. Since the gas in the cylinder is NIST traceable and of known concentration and the air flow of the zero air generator is known, the instrument can be verified and or calibrated. Thus the traceability of the NIST concentration in the cylinder is transferred to the instrument.

In addition to verifying or calibrating the instruments with NO gas, the multi-gas dilution calibrator has the ability to mix a diluted NO gas mixture with ozone. This process is known as a gas phase titration (GPT). When NO is mixed in a chamber with ozone, it immediately converts the NO to NO2.

The GPT provides a very important function for the NOX/NOY analyzer; testing of the Molycon’s ability to convert NO2 to NO. The procedure for performing the GPT is described in detail in the SOP for NOX/NOY analyzers. As noted previously, the NOY analyzer has a Molycon exterior to the analyzer and is mounted on top of a 10-meter tower. The NO/ NO2 gas from the dilution calibrator must be pumped through a Teflon line to the Molycon so that it can sample the mixture and convert the NO2 to NO and be measured by the NOY analyzer.

Figure 4 illustrates the configuration of the monitoring equipment and the placement of this

Section 11 equipment at a typical monitoring site.

Figure 4. Configuration of Monitoring Equipment in the Instrument Rack

11.8 Standard Operating Procedures

An SOP has been developed to provide instructions to the Site Operators regarding the routine operation of the NOX/NOY analyzers. The SOP for NOX/NOY analyzers covers the manual zero, span, precision checks, and calibrations. Equipment inspection, acceptance testing, visual inspections and preventive maintenance are detailed in the operations manual that accompanied the analyzer upon purchase. The SOP for NOX/NOy analyzers is an independent document that is a companion to this QAPP.