Proposed Rule2023-03578
Reference Measurement Principle and Calibration Procedure for the Measurement of Ozone in the Atmosphere (Chemiluminescence Method)
Primary source
Metadata and text below are from the Federal Register, a public-domain U.S. government work. Always verify the official published version before relying on it for any legal matter.
Published
February 24, 2023
Issuing agencies
Environmental Protection Agency
Abstract
The Environmental Protection Agency (EPA) is proposing to update the current ozone absorption cross-section to the recommended consensus-based cross-section value of 1.1329x10<SUP>-</SUP>\17\ cm\2\ molecule<SUP>-</SUP>\1\ or 304.39 atm<SUP>-</SUP>\1\ cm<SUP>-</SUP>\1\, with an uncertainty of 0.94 atm<SUP>-</SUP>\1\ cm<SUP>-</SUP>\1\. The new value is 1.2% lower than the current value of 308 atm<SUP>-</SUP>\1\ cm<SUP>-</SUP>\1\, and reduces the uncertainty in the value to 0.31%. The adoption of this updated ozone absorption cross-section could result in increases in measured ozone concentrations but given the existing sources of potential variability in monitoring data, it is unlikely that there would be any consistent measurable and predictable effect on reported data. The EPA is also proposing to update the dates of publication for two references, add a new reference for the updated cross-section value, and move the figures inadvertently placed in Section 6.0 References to a new Section 7.0 Figures.
Full Text
<html>
<head>
<title>Federal Register, Volume 88 Issue 37 (Friday, February 24, 2023)</title>
</head>
<body><pre>
[Federal Register Volume 88, Number 37 (Friday, February 24, 2023)]
[Proposed Rules]
[Pages 11835-11842]
From the Federal Register Online via the Government Publishing Office [<a href="http://www.gpo.gov">www.gpo.gov</a>]
[FR Doc No: 2023-03578]
=======================================================================
-----------------------------------------------------------------------
ENVIRONMENTAL PROTECTION AGENCY
40 CFR Part 50
[EPA-HQ-OAR-2022-0007; FRL 9344-01-OAR]
RIN 2060-AV63
Reference Measurement Principle and Calibration Procedure for the
Measurement of Ozone in the Atmosphere (Chemiluminescence Method)
AGENCY: Environmental Protection Agency (EPA).
ACTION: Proposed rule.
-----------------------------------------------------------------------
SUMMARY: The Environmental Protection Agency (EPA) is proposing to
update the current ozone absorption cross-section to the recommended
consensus-based cross-section value of 1.1329x10<SUP>-</SUP>\17\ cm\2\
molecule<SUP>-</SUP>\1\ or 304.39 atm<SUP>-</SUP>\1\ cm<SUP>-</SUP>\1\,
with an uncertainty of 0.94 atm<SUP>-</SUP>\1\ cm<SUP>-</SUP>\1\. The
new value is 1.2% lower than the current value of 308
atm<SUP>-</SUP>\1\ cm<SUP>-</SUP>\1\, and reduces the uncertainty in
the value to 0.31%. The adoption of this updated ozone absorption
cross-section could result in increases in measured ozone
concentrations but given the existing sources of potential variability
in monitoring data, it is unlikely that there would be any consistent
measurable and predictable effect on reported data. The EPA is also
proposing to update the dates of publication for two references, add a
new reference for the updated cross-section value, and move the figures
inadvertently placed in Section 6.0 References to a new Section 7.0
Figures.
DATES: Comments must be received on or before March 27, 2023.
Public hearing: If requested by March 1, 2023, the EPA will hold a
virtual public hearing on March 17, 2023. Please refer to the
SUPPLEMENTARY INFORMATION section for additional information on the
public hearing.
ADDRESSES:
Comments. You may send your comments, identified by Docket ID No.
EPA-HQ-OAR-2022-0007, by any of the following methods:
<bullet> Federal eRulemaking Portal:<a href="https://www.regulations.gov/">https://www.regulations.gov/</a>
(our preferred method). Follow the online instructions for submitting
comments.
<bullet> Email: <a href="/cdn-cgi/l/email-protection#52337f333c367f207f163d31393726123722337c353d24"><span class="__cf_email__" data-cfemail="98f9b5f9f6fcb5eab5dcf7fbf3fdecd8fde8f9b6fff7ee">[email protected]</span></a>. Include Docket ID No. EPA-
HQ-OAR-2022-0007 in the subject line of the message.
<bullet> Mail: U.S. Environmental Protection Agency, EPA Docket
Center, Air and Radiation Docket, Mail Code 28221T, 1200 Pennsylvania
Avenue NW, Washington, DC 20460.
<bullet> Hand Delivery or Courier (by scheduled appointment only):
EPA Docket Center, WJC West Building, Room 3334, 1301 Constitution
Avenue NW, Washington, DC 20004. The Docket Center's hours of
operations are 8:30 a.m.--4:30 p.m., Monday-Friday (except Federal
Holidays).
Instructions: All submissions received must include the Docket ID
No. for this rulemaking. Comments received may be posted without change
to <a href="https://www.regulations.gov/">https://www.regulations.gov/</a>, including any personal information
provided. For detailed instructions on sending comments and additional
information on the rulemaking process, see the ``Public Participation''
heading of the SUPPLEMENTARY INFORMATION section of this document.
FOR FURTHER INFORMATION CONTACT: Ms. Joann Rice, Office of Air Quality
Planning and Standards, Air Quality Assessment Division, Ambient Air
Monitoring Group (C304-06), Environmental Protection Agency, Research
Triangle Park, North Carolina 27711; telephone number: (919) 541-3372;
email address: <a href="/cdn-cgi/l/email-protection#ef9d868c8ac185808e8181af8a9f8ec1888099"><span class="__cf_email__" data-cfemail="d4a6bdb7b1fabebbb5baba94b1a4b5fab3bba2">[email protected]</span></a>.
SUPPLEMENTARY INFORMATION: The supplementary information in this
preamble is organized as follows:
I. Public Participation
A. Written Comments
B. Participation in Virtual Public Hearing
II. Background and Proposal
III. Statutory and Executive Orders Reviews
A. Executive Order 12866: Regulatory Planning and Review and
Executive Order 13563: Improving Regulation and Regulatory Review
B. Paperwork Reduction Act (PRA)
C. Regulatory Flexibility Act (RFA)
D. Unfunded Mandates Reform Act (UMRA)
E. Executive Order 13132: Federalism
[[Page 11836]]
F. Executive Order 13175: Consultation and Coordination With
Indian Tribal Governments
G. Executive Order 13045: Protection of Children From
Environmental Health Risks and Safety Risks
H. Executive Order 13211: Actions Concerning Regulations That
Significantly Affect Energy Supply, Distribution or Use
I. National Technology Transfer and Advancement Act (NTTAA)
J. Executive Order 12898: Federal Actions To Address
Environmental Justice in Minority Populations and Low-Income
Populations
I. Public Participation
A. Written Comments
Submit your comments, identified by Docket ID No. EPA-HQ-OAR-2022-
0007, at <a href="https://www.regulations.gov">https://www.regulations.gov</a> (our preferred method), or the
other methods identified in the ADDRESSES section. Once submitted,
comments cannot be edited or removed from the docket. The EPA may
publish any comment received to its public docket. Do not submit to
EPA's docket at <a href="https://www.regulations.gov">https://www.regulations.gov</a> any information you
consider to be Confidential Business Information (CBI), Proprietary
Business Information (PBI), or other information whose disclosure is
restricted by statute. Multimedia submissions (audio, video, etc.) must
be accompanied by a written comment. The written comment is considered
the official comment and should include discussion of all points you
wish to make. The EPA will generally not consider comments or comment
contents located outside of the primary submission (i.e., on the web,
cloud, or other file sharing system). Please visit <a href="https://www.epa.gov/dockets/commenting-epa-dockets">https://www.epa.gov/dockets/commenting-epa-dockets</a> for additional submission methods; the
full EPA public comment policy; information about CBI, PBI, or
multimedia submissions; and general guidance on making effective
comments.
B. Participation in Virtual Public Hearing
The EPA will begin pre-registering speakers for the hearing upon
publication of this document in the Federal Register. To register to
speak at the virtual hearing, please contact Ms. Joann Rice at (919)
541-3372 or <a href="/cdn-cgi/l/email-protection#d8aab1bbbdf6b2b7b9b6b698bda8b9f6bfb7ae"><span class="__cf_email__" data-cfemail="e4968d8781ca8e8b858a8aa4819485ca838b92">[email protected]</span></a>. The last day to pre-register to speak
at the hearing will be March 10, 2023. On March 16, 2023, the EPA will
post a general agenda for the hearing that will list pre-registered
speakers in approximate order at: <a href="https://www.epa.gov/amtic">https://www.epa.gov/amtic</a>.
The EPA will make every effort to follow the schedule as closely as
possible on the day of the hearing; however, please plan for the
hearings to run either ahead of schedule or behind schedule.
The EPA encourages commenters to provide the EPA with a copy of
their oral testimony electronically by emailing it to
<a href="/cdn-cgi/l/email-protection#2e5c474d4b0044414f40406e4b5e4f00494158"><span class="__cf_email__" data-cfemail="0a7863696f2460656b64644a6f7a6b246d657c">[email protected]</span></a>. The EPA also recommends submitting the text of your
oral comments as written comments to the rulemaking docket.
The EPA may ask clarifying questions during the oral presentations
but will not respond to the presentations at that time. Written
statements and supporting information submitted during the comment
period will be considered with the same weight as oral comments and
supporting information presented at the public hearing.
Please note that any updates made to any aspect of the hearing are
posted online at <a href="https://www.epa.gov/amtic">https://www.epa.gov/amtic</a>. While the EPA expects the
hearing to go forward as set forth above, please monitor our website or
contact Ms. Joann Rice at (919) 541-3372 or <a href="/cdn-cgi/l/email-protection#0f7d666c6a2165606e61614f6a7f6e21686079"><span class="__cf_email__" data-cfemail="d7a5beb4b2f9bdb8b6b9b997b2a7b6f9b0b8a1">[email protected]</span></a> to
determine if there are any updates. The EPA does not intend to publish
a document in the Federal Register announcing updates.
II. Background and Proposal
In 1961, the ozone absorption cross-section was measured to be
1.1476 x10<SUP>-</SUP>\17\ cm\2\ molecule<SUP>-</SUP>\1\ or 308.3
atm<SUP>-</SUP>\1\ cm<SUP>-</SUP>\1\ with a reported relative standard
uncertainty of 1.4% (Hearn, 1961). In the 1980s, the National Institute
of Standards and Technology (NIST), in collaboration with the EPA,
developed the Standard Reference Photometer (SRP), which is the
international standard for the measurement of ozone. The SRP is based
on ultraviolet (UV) photometry and uses this cross-section value as the
reference value for UV ozone measurements. To establish and maintain
traceability, the readings of an ozone analyzer are compared through a
hierarchy of standards to a NIST-made ozone SRP. Efforts to improve the
accuracy of the ozone absorption cross-section have continued over
several years and rigorous assessment of the bias and uncertainty in
the value became a high priority.
The Gas Analysis Working Group of the Consultive Committee for
Metrology in Chemistry and Biology (CCQM-GAWG) of the Bureau of Weights
and Measures in France (BIPM) convened a task group in 2016 to review
all published measurements of the ozone cross-section since 1950. This
task group was also charged with recommending a consensus-based cross-
section value and associated uncertainty to be adopted in standard UV
photometric instruments, including the SRP, for measurements of ozone
concentrations (Hodges et al., 2019).
After publication in Hodges et al., 2019, the CCQM-GAWG \1\
convened an international group of stakeholders in October 2020 to
discuss adopting and implementing a globally coordinated change in the
cross-section value for surface ozone monitoring. This group,
representing several international and national metrology institutes,
NIST, and environmental agencies including EPA, agreed to adopt and
implement the new cross-section value as it represents a more accurate
value with less uncertainty and is an advancement and improvement in
the UV photometer measurement method.
---------------------------------------------------------------------------
\1\ <a href="https://www.bipm.org/en/committees/cc/ccqm/wg/ccqm-gawg-ozone-tg">https://www.bipm.org/en/committees/cc/ccqm/wg/ccqm-gawg-ozone-tg</a>.
---------------------------------------------------------------------------
40 CFR part 50, Appendix D, ``Reference Measurement Principle and
Calibration Procedure for the Measurement of Ozone in the Atmosphere,''
currently provides EPA's ozone calibration procedure with a stated
value of 308 <plus-minus> 4 atmosphere atm<SUP>-</SUP>\1\
cm<SUP>-</SUP>\1\. The proposed revision would change the ozone
absorption cross-section and amend relevant references to align
internationally with the BIPM CCQM-GAWG's updated cross-section value
of 304.39 atm<SUP>-</SUP>\1\ cm<SUP>-</SUP>\1\ with an uncertainty of
0.94 atm<SUP>-</SUP>\1\ cm<SUP>-</SUP>\1\ at standard temperature and
pressure of 0[deg]C and 1 atmosphere. The EPA agrees that the new
cross-section value would result in an improvement in the accuracy of
surface ozone monitoring measurements by reducing uncertainty and is
seeking comment on our proposed change from the UV absorption cross-
section value in Appendix D of Part 50 to this more accurate consensus
value.
The new value would reduce the uncertainty to 0.31% from the
current 1.4%. The new value would also be 1.2% lower than the current
value, a change that could result in increases in measured ozone
concentrations. However, there are several factors that EPA believes
would make it unlikely that this change would have a measurable,
predictable influence on any particular set of ozone monitoring data.
Design Values, the metric used to compare ambient ozone
concentrations measured at a monitor to the National Ambient Air
Quality Standard (NAAQS) to determine compliance, are determined using
the data reporting, data handling, and computation procedures provided
in 40 CFR part 50, Appendix U, ``Interpretation of the Primary and
Secondary National
[[Page 11837]]
Ambient Air Quality Standards for Ozone.''
Multiple factors can contribute to variability in monitoring data,
including but not limited to the precision of the monitoring method,
the acceptance criteria for Standard Reference Photometer (SRP)
calibration and verification, the acceptance criterion for bench and
field standards used to calibrate ozone monitors in the field, how
agencies perform calibration and adjust analyzer response, the
precision and bias acceptance criteria in EPA's Quality Assurance (QA)
Handbook,\2\ data handling and computation procedures in Appendix U,
and meteorology.
---------------------------------------------------------------------------
\2\ Quality Assurance Handbook for Air Pollution Measurement
Systems, Volume II, EPA-454/B-17-001, Jan. 2017, available at:
<a href="https://www.epa.gov/sites/default/files/2020-10/documents/final_handbook_document_1_17.pdf">https://www.epa.gov/sites/default/files/2020-10/documents/final_handbook_document_1_17.pdf</a>.
---------------------------------------------------------------------------
The inherent precision (variability) of the measurements from
analyzers used to measure ozone is about <plus-minus>1 ppb, or <plus-
minus>0.001 ppm. The variability in the measurement in either the
positive or negative direction should be considered relative to the
change in monitoring data due to the new cross-section value.
When the new cross-section value is implemented, all SRPs
maintained by BIPM, NIST, and the EPA will be updated to incorporate
the new value. The update would be achieved through software/firmware
modification and would not require any hardware changes. The EPA is
proposing to modify the EPA SRPs simultaneously, versus through a
phased approach, to minimize disruption of the SRP network. To
establish and maintain traceability, the readings of an ozone analyzer
are compared through a hierarchy of standards to a NIST ozone SRP. The
process of using NIST-traceable standards to verify the ozone
concentrations is implemented for all regulatory network ozone
analyzers used for comparison to the NAAQS. There are 12 SRPs within
the EPA's network: three at EPA's Office of Research and Development
(ORD) and nine at various EPA Regional offices and the California Air
Resources Board (CARB). One of ORD's SRPs is sent to NIST to be re-
verified against the NIST SRP annually. That SRP serves as the
reference for the two other ORD SRPs. Each SRP in the U.S. is re-
verified against one of ORD's three SRPs annually. Under normal
verification operations, implementing the ozone standards traceability
process for the entire SRP network could take two or more years
starting from when the SRP software/firmware is updated. During this
time, the implementation progress and monitoring data collected with
the new cross-section would need to be tracked.
The acceptance criteria used in comparing the SRPs (Level 1
standards) to each other is a slope of 1.00 <plus-minus> 0.01 (or 1%)
and an intercept 0.00 <plus-minus> 1 ppb. Field and bench standards
(Level 2 standard) used to calibrate ozone analyzers in the field have
acceptance criteria for the slope of 1.00 <plus-minus> 0.03 (or 3%) and
an intercept of 0 <plus-minus> 3 ppb. The 1.2% change in cross-section
value is well within the 3% acceptance for Level 2 standards.
The goal for measurement uncertainty for ozone in 40 CFR part 58,
``Ambient Air Quality Surveillance,'' for an annual measurement
uncertainty is an upper 90 percent confidence limit for the coefficient
of variation of 7% for precision and for bias an upper 95 percent
confidence limit of 7%. Bias and precision estimates are determined
using data obtained from the comparison of the ozone analyzer response
to one point Quality Control (QC) checks using a Level 2 calibration
standard. The 1.2% change in cross-section value is well within the
bias and precision goal of 7%. Data reported to the EPA's Air Quality
System by state, local, and tribal monitoring agencies is used to
assess bias and precision. The 2021 national average precision for all
ozone analyzers in the U.S. is 2.3% and the national average bias is
1.6%.\3\ The 1.2% change is, therefore, within the national precision
and less than the national bias.
---------------------------------------------------------------------------
\3\ Data obtained on 9/1/2022 from EPA's Ozone Data Quality
Dashboard: <a href="https://sti-r-shiny.shinyapps.io/ozone_dashboard/">https://sti-r-shiny.shinyapps.io/ozone_dashboard/</a>.
---------------------------------------------------------------------------
The QA Handbook, Volume II, Appendix D Validation Template \4\ also
specifies critical criteria for monitoring organizations to maintain
the integrity and evaluate the quality of the data collected by the
analyzer. The critical criteria are a one-point QC check (every 14 days
at a minimum) < <plus-minus>7.1% difference or < <plus-minus>1.5 ppb
difference, whichever is greater; zero drift < <plus-minus> 3.1 ppb
(over a 24-hour period) or < <plus-minus>5.1 ppb (> 24 hours and up to
14 days); and span check drift over a 14-day period of < <plus-
minus>7.1%. Any change to monitoring data due to the new cross-section
is also well within the 7.1% acceptance criteria. Monitoring
organizations may manually adjust the analyzer response and others may
institute automated adjustment through use of a data acquisition or
data handling system. Automated adjustments to the ozone analyzer data
are not recommended because the monitoring agency may not know if the
standard being used for monitor comparison, or the analyzer, has
degraded or drifted.
---------------------------------------------------------------------------
\4\ Appendix D, Measurement Quality Objectives and Validation
Templates: <a href="https://www.epa.gov/sites/default/files/2020-10/documents/app_d_validation_template_version_03_2017_for_amtic_rev_1.pdf">https://www.epa.gov/sites/default/files/2020-10/documents/app_d_validation_template_version_03_2017_for_amtic_rev_1.pdf</a>.
---------------------------------------------------------------------------
Ozone analyzers are calibrated or verified every 182 days if one-
point zero and span checks are performed every 14 days, and every 365
days if one-point zero and span checks are done daily. The acceptance
criteria for multi-point calibration is all points < <plus-minus>2.1%
or <= <plus-minus>1.5 ppb difference of the best fit straight line,
whichever is greater, and a slope of 1 <plus-minus> 0.05 or 5%. The
1.2% change is also well within this acceptance criteria for
calibration.
Design values are the 3-year average of the annual 4th highest
daily maximum 8-hour value measured at each monitoring site. If the
proposed cross-section value is timely adopted, design values for 2026
will have all three years (2024-2026) of monitoring data generated with
the new cross-section value. Design values for 2024 will have one year
based on the new value, and design values for 2025 will have two years
of monitoring data generated with the new value. Appendix U provides
for three levels of truncation for the hourly, daily 8-hour maximum,
and design value calculations. Hourly averaged ozone monitoring data
are to be reported in ppm to the third decimal place, with additional
digits to the right truncated (e.g., 0.070 ppm).
In assessing how and if this proposed change may affect ozone
design values, it is important to note that other factors, including
meteorology, can also influence design values. The effects of
meteorology on hourly ozone concentrations can contribute to an
increase or decrease in design values for a site because formation of
ozone is heavily dependent on meteorological conditions. Interannual
meteorological variations are known to affect daily and seasonal
average ozone concentrations. Therefore, while we do not have reason to
believe this proposal will significantly increase design values,
meteorology would be a confounding factor in determining the effect of
today's proposal on 3-year design values.
Taking these factors into consideration, EPA believes it is
unlikely that the proposed cross section change will have a measurable,
predictable influence on any given ozone design value or monitoring
data set.
Because the EPA believes that adoption of the new cross-section
would improve the accuracy of measured
[[Page 11838]]
ozone values, but would be unlikely to have a measurable, predictable
influence on any given monitor or design value, the EPA supports and
proposes to revise the current ozone absorption cross-section to the
recommended international consensus-based cross-section value of 304.39
atm<SUP>-</SUP>\1\ cm<SUP>-</SUP>\1\, with an uncertainty of 0.94
atm<SUP>-</SUP>\1\ cm<SUP>-</SUP>\1\.
II. Statutory and Executive Orders Reviews
Additional information about these statutes and Executive Orders
can be found at <a href="https://www.epa.gov/laws-regulations/laws-and-executive-orders">https://www.epa.gov/laws-regulations/laws-and-executive-orders</a>.
A. Executive Order 12866: Regulatory Planning and Review and Executive
Order 13563: Improving Regulation and Regulatory Review
This action is not a significant regulatory action and was,
therefore, not submitted to the Office of Management and Budget (OMB)
for review.
B. Paperwork Reduction Act (PRA)
This action does not impose an information collection burden under
the PRA. This action proposes to revise the ozone absorption cross-
section and revise and amend relevant references. It does not contain
any information collection activities.
C. Regulatory Flexibility Act (RFA)
I certify that this action will not have a significant economic
impact on a substantial number of small entities under the RFA. In
making this determination, the EPA concludes that the impact of concern
for this rule is any significant adverse economic impact on small
entities and that the agency is certifying that this rule will not have
a significant economic impact on a substantial number of small entities
if the rule has no net burden on the small entities subject to the
rule. This proposed action would update the ozone absorption cross-
section value for surface ozone monitoring under 40 CFR part 50, and we
anticipate that there will be minimal costs associated with this
change. We have, therefore, concluded that this action will have no net
regulatory burden for all directly regulated small entities.
D. Unfunded Mandates Reform Act (UMRA)
This action does not contain any unfunded mandate as described in
UMRA, 2 U.S.C. 1531-1538 and does not significantly or uniquely affect
small governments. This action imposes no enforceable duty on any
state, local, or tribal governments, or the private sector.
E. Executive Order 13132: Federalism
This action does not have federalism implications. It will not have
substantial direct effects on the states, on the relationship between
the national government and the states, or on the distribution of power
and responsibilities among the various levels of government.
F. Executive Order 13175: Consultation and Coordination With Indian
Tribal Governments
This action does not have tribal implications as specified in
Executive Order 13175. This action proposes updates to a reference
measurement principle and calibration procedure for the measurement of
ambient ozone under 40 CFR part 50. Thus, Executive Order 13175 does
not apply to this action.
G. Executive Order 13045: Protection of Children From Environmental
Health Risks and Safety Risks
The EPA interprets Executive Order 13045 as applying only to those
regulatory actions that concern environmental health or safety risks
that the EPA has reason to believe may disproportionately affect
children, per the definition of ``covered regulatory action'' in
section 2-202 of the Executive Order. This action is not subject to
Executive Order 13045 because it does not concern an environmental
health risk or safety risk.
H. Executive Order 13211: Actions Concerning Regulations That
Significantly Affect Energy Supply, Distribution or Use
This action is not subject to Executive Order 13211, because it is
not a significant regulatory action under Executive Order 12866.
I. National Technology Transfer and Advancement Act (NTTAA)
This rulemaking involves technical standards. The EPA used
voluntary consensus standards in the preparation of this measurement
principle and procedure; it is the benchmark against which all ambient
ozone monitoring methods are compared. This action is simply updating
the reference measurement principle in light of updated information.
J. Executive Order 12898: Federal Actions To Address Environmental
Justice in Minority Populations and Low-Income Populations
Executive Order 12898 (59 FR 7629, Feb. 16, 1994) directs Federal
agencies, to the greatest extent practicable and permitted by law, to
make environmental justice part of their mission by identifying and
addressing, as appropriate, disproportionately high and adverse human
health or environmental effects of their programs, policies, and
activities on minority populations (people of color) and low-income
populations.
The EPA believes that this type of action does not concern human
health or environmental conditions and, therefore, cannot be evaluated
with respect to potentially disproportionate and adverse effects on
people of color, low-income populations and/or indigenous peoples. This
regulatory action is an update to a previously promulgated analytical
method and does not have any impact on human health or the environment.
References
Hearn A. G. (1961). Absorption of ozone in ultra-violet and visible
regions of spectrum Proc. Phys. Soc. 78 932-40
Hodges, J.T., Viallon, J., Brewer, P.J., Drouin, B.J., Gorshelev,
V., Janssen, C., Lee, S., Possolo, A., Smith, M.A.H., Walden, and
Wielgosz, R.I. (2019). Recommendation of a consensus value of the
ozone absorption cross-section at 253.65 nm based on a literature
review, Metrologia, 56, 034001. <a href="https://doi.org/10.1088/1681-7575/ab0bdd">https://doi.org/10.1088/1681-7575/ab0bdd</a>.
List of Subjects 40 CFR Part 50
Environmental protection, Air pollution control, Ozone.
Michael S. Regan,
Administrator.
For the reasons set forth in the preamble, the EPA proposes to
amend 40 CFR part 50 as follows:
PART 50--NATIONAL PRIMARY AND SECONDARY AMBIENT AIR QUALITY
STANDARDS
0
1. The authority citation for part 50 continues to read as follows:
Authority: 42 U.S.C. 7401, et seq.
0
2. Amend Appendix D to part 50 by:
0
a. In Section 4.0, revising paragraphs 4.1 and 4.5.3.10;
0
b. In Section 6.0, revising references 12 and 14, removing figures 1, 2
and 3, adding reference 15; and
0
c. Adding new Section 7.0.
The revisions and addition read as follows.
Appendix D to Part 50--Reference Measurement Principle and Calibration
Procedure for the Measurement of Ozone in the Atmosphere
(Chemiluminescence Method)
* * * * *
[[Page 11839]]
4.0 Calibration Procedure
4.1 Principle. The calibration procedure is based on the
photometric assay of O<INF>3</INF> concentrations in a dynamic flow
system. The concentration of O<INF>3</INF> in an absorption cell is
determined from a measurement of the amount of 254 nm light absorbed
by the sample. This determination requires knowledge of (1) the
absorption coefficient ([alpha]) of O<INF>3</INF> at 254 nm, (2) the
optical path length (l) through the sample, (3) the transmittance of
the sample at a nominal wavelength of 254 nm, and (4) the
temperature (T) and pressure (P) of the sample. The transmittance is
defined as the ratio I/I<INF>0,</INF> where I is the intensity of
light which passes through the cell and is sensed by the detector
when the cell contains an O<INF>3</INF> sample, and I<INF>0</INF> is
the intensity of light which passes through the cell and is sensed
by the detector when the cell contains zero air. It is assumed that
all conditions of the system, except for the contents of the
absorption cell, are identical during measurement of I and
I<INF>0</INF>. The quantities defined above are related by the Beer-
Lambert absorption law,
[GRAPHIC] [TIFF OMITTED] TP24FE23.098
Where:
[alpha] = absorption coefficient of O<INF>3</INF> at 254 nm = 304.39
atm<SUP>-1</SUP> cm<SUP>-1</SUP>, with an uncertainty of 0.94
atm<SUP>-1</SUP> cm<SUP>-1</SUP> at 0 [deg]C and 1
atm.<SUP>1 2 3 4 5 6 7 15</SUP>
c = O<INF>3</INF> concentration in atmospheres, and
l = optical path length in cm.
A stable O<INF>3</INF> generator is used to produce O<INF>3</INF>
concentrations over the required calibration concentration range. Each
O<INF>3</INF> concentration is determined from the measurement of the
transmittance (I/I<INF>0</INF>) of the sample at 254 nm with a
photometer of path length l and calculated from the equation,
[GRAPHIC] [TIFF OMITTED] TP24FE23.099
The calculated O<INF>3</INF> concentrations must be corrected for
O<INF>3</INF> losses, which may occur in the photometer, and for the
temperature and pressure of the sample.
* * * * *
4.5.3.10. Calculate the O<INF>3</INF> concentration from equation
4. An average of several determinations will provide better precision.
[GRAPHIC] [TIFF OMITTED] TP24FE23.100
Where:
[O<INF>3</INF>]<INF>OUT</INF> = O<INF>3</INF> concentration, ppm
[alpha] = absorption coefficient of O<INF>3</INF> at 254 nm = 304.39
atm<SUP>-1</SUP> cm<SUP>-1</SUP> at 0 [deg]C and 1 atm
l = optical path length, cm
T = sample temperature, K
P = sample pressure, torr
L = correction factor for O<INF>3</INF> losses from 4.5.2.5 = (1-
fraction of O<INF>3</INF> lost).
Note: Some commercial photometers may automatically evaluate
all or part of equation 4. It is the operator's responsibility to
verify that all of the information required for equation 4 is
obtained, either automatically by the photometer or manually. For
``automatic'' photometers which evaluate the first term of equation
4 based on a linear approximation, a manual correction may be
required, particularly at higher O<INF>3</INF> levels. See the
photometer instruction manual and Reference 13 for guidance.
* * * * *
6.0 References
* * * * *
12. Transfer Standards for Calibration of Ambient Air Monitoring
Analyzers for Ozone, EPA publication number EPA-454/B-22-003, December
2022.
* * * * *
14. QA Handbook for Air Pollution Measurement Systems--Volume II.
Ambient Air Quality Monitoring Program. EPA-454/B-17-001, January 2017.
15. Hodges, J.T., Viallon, J., Brewer, P.J., Drouin, B.J., Gorshelev,
V., Janssen, C., Lee, S., Possolo, A., Smith, M.A.H., Walden, and
Wielgosz, R.I., Recommendation of a consensus value of the ozone
absorption cross-section at 253.65 nm based on a literature review,
Metrologia, 56 (2019) 034001. [Available at <a href="https://doi.org/10.1088/1681-7575/ab0bdd">https://doi.org/10.1088/1681-7575/ab0bdd</a>.]
[[Page 11840]]
7.0 Figures
[GRAPHIC] [TIFF OMITTED] TP24FE23.101
Figure 1 of Section 7 to Appendix D of Part 50--Gas-phase
chemiluminescence analyzer schematic diagram, where PMT means
photomultiplier tube.
[[Page 11841]]
[GRAPHIC] [TIFF OMITTED] TP24FE23.102
Figure 2 of Section 7 to Appendix D of Part 50--Schematic diagram of a
typical UV photometric calibration system.
[[Page 11842]]
[GRAPHIC] [TIFF OMITTED] TP24FE23.103
Figure 3 of Section 7 to Appendix D of Part 50--Schematic diagram of a
typical UV photometric calibration system (Option 1).
[FR Doc. 2023-03578 Filed 2-23-23; 8:45 am]
BILLING CODE 6560-50-P
</pre><script data-cfasync="false" src="/cdn-cgi/scripts/5c5dd728/cloudflare-static/email-decode.min.js"></script></body>
</html>Indexed from Federal Register on February 24, 2023.
This is legal information, not legal advice. Laws vary by jurisdiction and change frequently. Always verify current law with official sources and consult a licensed attorney in your jurisdiction for advice on your specific situation.