Exhibit B EPA Protocol.pdf

UNITED STATES ENVIRONMENTAL PROTECTION AGENCY

RESEARCH TRIANGLE PARK, NC 27711

OFFICE OF

AIR QUALITY PLANNING

AND STANDARDS

February 25, 2022

MEMORANDUM

SUBJECT: EPA Protocol Gas Long-Term Stability Requirements

FROM: Douglas Jager, EPA-OAQPS, Ambient Air Monitoring Group

Bob Wright, EPA-ORD, Air Methods and Characterization Division

TO: EPA Regional Offices, Regulatory Agencies Performing Ambient Air Monitoring, and Specialty Gas Producers

This memorandum provides notification to specialty gas producers and to State, Local, and Tribal (SLT) ambient air monitoring programs that gaseous calibration standards used for the calibration and the QA/QC of monitors intended to demonstrate compliance with the National Ambient Air Quality Standards (NAAQS) must be EPA Protocol

Gases. The EPA Traceability Protocol for Assay and Certification of Gaseous

Calibration Standards defines the assay requirements that must be followed for a candidate standard to be certified as an EPA Protocol Gas, including a seven-day stability test for reactive gas mixtures. Candidate standards that pass the stability test are assumed to be stable throughout the maximum certification periods that are listed in

Table 2-3 of the protocol (see attached). These periods are based on the certification periods for the corresponding Standard Reference Materials (SRMs) from the National

Institute of Standards and Technology (NIST), which has evaluated SRM stability over multiple years. Gas mixtures that are not listed in Table 2-3 have not been demonstrated to have long-term stability and cannot be certified as EPA Protocol Gases.

EPA is aware that, in some cases, SO2-in-air and NO2-in-N2 standards may have been certified by specialty gas producers as EPA Protocol Gases. These standards are not listed in Table 2-3 of the protocol and are not EPA Protocol Gases. EPA is working with the producers to notify them to cease certifying or otherwise indicating that these standards are EPA Protocol Gases until their long-term stability has been demonstrated to EPA and the protocol has been revised to include them in Table 2-3.

Some proprietary interior surface coatings for cylinders are available (e.g., Luxfer

Superior Gas Stability (SGS™) cylinders and Catalina Mirror Finish™ cylinders) that are designed to increase the stability of reactive gas mixtures such as NO2-in-N2. Some national metrology institutes (NMIs), e.g., the Netherlands' NMI, the Van Swinden

Laboratory (VSL), use these cylinders for storing their NO2-in-N2 Primary Reference

Materials (PRMs). To date however, EPA has not received adequate long-term stability data for the commercially prepared NO2-in-N2 standards in these cylinders to determine the appropriate maximum certification period for NO2-in-N2 as an EPA Protocol Gas.

Jager, Doug Digitally signed by Jager, Doug Date: 2022.02.25 09:01:31 -05'00'

ROBERT

WRIGHT

Digitally signed by

ROBERT WRIGHT

Date: 2022.02.25 09:26:10 -05'00'

EXHIBIT B

EPA is recommending that SLT ambient air monitoring programs review the certificates of analysis for their gaseous calibration standards to ensure they are listed in Table 2-3 of the protocol. SLTs should focus their review to ensure that:

• no SO2 standards with an air balance are used for regulatory monitoring. These standards are not EPA Protocol Gases and as such do not meet the regulatory

QA requirements found in Section 2.6.1 of 40 CFR Part 58, Appendix A.

Additionally, Section 4.1.6 of 40 CFR Part 50, Appendix A-1 requires that the

SO2 standards be balanced with N2, not with air; and

• no NO2-in-N2 standards are used for regulatory monitoring. These standards are not EPA Protocol Gases and as such do not meet the regulatory QA requirements found in Section 2.6.1 of 40 CFR Part 58, Appendix A.

Additionally, direct dilution of NO2 cylinder standards is not an approved method in 40 CFR Part 50, Appendix F for the generation of test atmospheres for NO2 analyzers.

Request for specialty gas producer data demonstrating long-term stability of SO2-in-air and NO2-in-N2 standards- Currently EPA is aware of long-term stability concerns for SO2-in-air and NO2-in-N2 standards that are stored in standard passivated aluminum cylinders. It is EPA’s understanding that some producers feel that they can reliably produce stable SO2-in-air and NO2-in-N2 standards. EPA encourages those producers to submit long-term stability data and supporting documentation to EPA by contacting Bob Wright at wright.bob@epa.gov. Stability results submitted to EPA-ORD by specialty gas producers will be treated as confidential business information (CBI). If the standards can be shown to EPA’s satisfaction to be stable, Table 2-3 will be revised to include these standards

EPA Regional offices should begin incorporating a review of the certificates of analyses for these SO2-in-air and NO2-in-N2 standards during scheduled Technical Systems

Audits. SLT ambient air monitoring programs identifying suspect SO2-in-air and NO2-in-N2 standards used for calibration or QA/QC of their regulatory ambient air monitoring network should notify their EPA Regional Office. This communication will facilitate EPA expediting the notification of specialty gas producers and will allow EPA to provide timely guidance with any data validation questions pertaining to the use of suspect calibration standards. EPA Regional Office Quality Assurance Coordinators should contact Doug Jager at jager.doug@epa.gov if they find SO2-in-air and NO2-in-N2 standards that are certified as EPA Protocol Gases.

cc: EPA Regional Office Air Monitoring Coordinators

EPA Regional Office Quality Assurance Coordinators

Protocol Gas Verification Program participants during Calendar Year 2022

Douglas Jager (EPA)

Gregory Noah (EPA)

Travis Johnson (EPA)

Bob Wright (EPA)

EPA Traceability Protocol for Gaseous Calibration Standards

TABLE 2-3. Maximum Certification Periodsa for Calibration Standards in Passivated Aluminum Cylinders

Components Balance gas Concentration range Period (years)

Ammonia Nitrogen 5 to 50 ppm 1

Carbon dioxide Airb 360 to 420 ppm 8

Carbon dioxide Nitrogen 5 ppm to 20% 8

Carbon monoxide Air 40 to 500 ppb TBD

Carbon monoxide Air 500 ppb to 10% 8

Carbon monoxide Nitrogen 1 ppm to 15% 8

Formaldehyde Nitrogen 0.5 to 10 ppm 1

Hydrogen chloridec Nitrogen 10 to 5000 ppm 2

Hydrogen sulfide Nitrogen 1 to 1000 ppm 3

Methane Air 1 to 1000 ppm 8

Methane Nitrogen 500 ppb to 10% 8

Methanol or ethanol

Nitrogen or Air 75 to 500 ppm 4

Natural gas componentsd

Natural gas Contact NIST

Nitric oxide O2-free nitrogene 0.5 to 50 ppm 3

Nitric oxide O2-free nitrogene 50 ppm to 1% 8

Nitrous oxide Air 300 ppb to 5% 8

Oxides of nitrogenf Air 3 ppm to 1% 3

Oxygen Nitrogen 10 ppm to 25% 8

Propane Air 0.1 to 500 ppm 8

Propane Nitrogen 5 ppb to 2% 8

Sulfur dioxide Nitrogen 1 to 50 ppm 4

Sulfur dioxide Nitrogen 50 ppm to 1%- 8

Volatile organics Nitrogen 1 ppb to 1 ppm 4

Zero air materialg Air Not applicable Unlimited

Multicomponent mixtures

— — See text

Mixtures with lower concentrations

— — See text a Specialty gas producers may elect to certify candidate standards for less than the maximum certification period. Each producer has discretion in this matter. See text.

b "Air" is defined as a mixture of oxygen and nitrogen where the minimum concentration of oxygen is 10 percent and the concentration of nitrogen is greater than 60 percent.

c Hydrogen chloride may be contained in passivated aluminum or nickel-coated steel cylinders.

d Natural gas components are methane, ethane, propane, n-butane, iso-butane, n-pentane, iso-pentane, helium, nitrogen, and carbon dioxide.

e O2-free nitrogen contains ≤ 100 ppb of oxygen.

f NIST defines its total NOX standards as containing nitrogen dioxide plus contaminant nitric acid.

g Concentrations of SO2, NOX, and THC are not >0.1 ppm; concentration of CO is not >1 ppm; and concentration of CO2 is not >400 ppm as per 40 CFR Part 72.2. Zero air material may be contained in steel cylinders.