Appendix C to Part 58 - Ambient Air Quality Monitoring Methodology
40:220.127.116.11.18.104.22.168.36 : Appendix C
Appendix C to Part 58 - Ambient Air Quality Monitoring Methodology
1.0 Purpose 2.0 SLAMS Ambient Air Monitoring Stations 3.0 NCore
Ambient Air Monitoring Stations 4.0 Photochemical Assessment
Monitoring Stations (PAMS) 5.0 Particulate Matter Episode
Monitoring 6.0 References 1.0 Purpose
This appendix specifies the criteria pollutant monitoring
methods (manual methods or automated analyzers) which must be used
in SLAMS and NCore stations that are a subset of SLAMS.
2.0 SLAMS Ambient Air Monitoring Network
2.1 Except as otherwise provided in this appendix, a criteria
pollutant monitoring method used for making NAAQS decisions at a
SLAMS site must be a reference or equivalent method as defined in §
50.1 of this chapter.
2.1.1 Any NO2 FRM or FEM used for making primary NAAQS decisions
must be capable of providing hourly averaged concentration
2.3 Any manual method or analyzer purchased prior to
cancellation of its reference or equivalent method designation
under § 53.11 or § 53.16 of this chapter may be used at a SLAMS
site following cancellation for a reasonable period of time to be
determined by the Administrator.
2.4 Approval of Non-designated Continuous PM 2.5 Methods as
Approved Regional Methods (ARMs) Operated Within a Network of
Sites. A method for PM 2.5 that has not been designated as an FRM
or FEM as defined in § 50.1 of this chapter may be approved as an
ARM for purposes of section 2.1 of this appendix at a particular
site or network of sites under the following stipulations.
2.4.1 The candidate ARM must be demonstrated to meet the
requirements for PM 2.5 Class III equivalent methods as defined in
subpart C of part 53 of this chapter. Specifically the requirements
for precision, correlation, and additive and multiplicative bias
apply. For purposes of this section 2.4, the following requirements
22.214.171.124 The candidate ARM shall be tested at the site(s) in
which it is intended to be used. For a network of sites operated by
one reporting agency or primary quality assurance organization, the
testing shall occur at a subset of sites to include one site in
each MSA/CSA, up to the first 2 highest population MSA/CSA and at
least one rural area or Micropolitan Statistical Area site. If the
candidate ARM for a network is already approved for purposes of
this section in another agency's network, subsequent testing shall
minimally occur at one site in a MSA/CSA and one rural area or
Micropolitan Statistical Area. There shall be no requirement for
tests at any other sites.
126.96.36.199 For purposes of this section, a full year of testing may
begin and end in any season, so long as all seasons are
188.8.131.52 No PM 10 samplers shall be required for the test, as
determination of the PM 2.5/PM 10 ratio at the test site shall not
184.108.40.206 The test specification for PM 2.5 Class III equivalent
method precision defined in subpart C of part 53 of this chapter
applies; however, there is no specific requirement that collocated
continuous monitors be operated for purposes of generating a
statistic for coefficient of variation (CV). To provide an estimate
of precision that meets the requirement identified in subpart C of
part 53 of this chapter, agencies may cite peer-reviewed published
data or data in AQS that can be presented demonstrating the
candidate ARM operated will produce data that meets the
specification for precision of Class III PM 2.5 methods.
220.127.116.11 A minimum of 90 valid sample pairs per site for the year
with no less than 20 valid sample pairs per season must be
generated for use in demonstrating that additive bias,
multiplicative bias and correlation meet the comparability
requirements specified in subpart C of part 53 of this chapter. A
valid sample pair may be generated with as little as one valid FRM
and one valid candidate ARM measurement per day.
18.104.22.168 For purposes of determining bias, FRM data with
concentrations less than 3 micrograms per cubic meter (µg/m 3) may
be excluded. Exclusion of data does not result in failure of sample
completeness specified in this section.
22.214.171.124 Data transformations are allowed to be used to
demonstrate meeting the comparability requirements specified in
subpart C of part 53 of this chapter. Data transformation may be
linear or non-linear, but must be applied in the same way to all
sites used in the testing.
2.4.2 The monitoring agency wishing to use an ARM must develop
and implement appropriate quality assurance procedures for the
method. Additionally, the following procedures are required for the
126.96.36.199 The ARM must be consistently operated throughout the
network. Exceptions to a consistent operation must be approved
according to section 2.8 of this appendix;
188.8.131.52 The ARM must be operated on an hourly sampling frequency
capable of providing data suitable for aggregation into daily
24-hour average measurements;
184.108.40.206 The ARM must use an inlet and separation device, as
needed, that are already approved in either the reference method
identified in appendix L to part 50 of this chapter or under part
53 of this chapter as approved for use on a PM 2.5 reference or
equivalent method. The only exceptions to this requirement are
those methods that by their inherent measurement principle may not
need an inlet or separation device that segregates the aerosol;
220.127.116.11 The ARM must be capable of providing for flow audits,
unless by its inherent measurement principle, measured flow is not
required. These flow audits are to be performed on the frequency
identified in appendix A to this part.
18.104.22.168 If data transformations are used, they must be described
in the monitoring agencies Quality Assurance Project plan (or
addendum to QAPP). The QAPP shall describe how often (e.g.,
quarterly, yearly) and under what provisions the data
transformation will be updated. For example, not meeting the data
quality objectives for a site over a season or year may be cause
for recalculating a data transformation, but by itself would not be
cause for invalidating the data. Data transformations must be
applied prospectively, i.e., in real-time or near real-time, to the
data output from the PM 2.5 continuous method. See reference 7 of
2.4.3 The monitoring agency wishing to use the method must
develop and implement appropriate procedures for assessing and
reporting the precision and accuracy of the method comparable to
the procedures set forth in appendix A of this part for designated
reference and equivalent methods.
2.4.4 Assessments of data quality shall follow the same
frequencies and calculations as required under section 3 of
appendix A to this part with the following exceptions:
22.214.171.124 Collocation of ARM with FRM/FEM samplers must be
maintained at a minimum of 30 percent of the required SLAMS sites
with a minimum of 1 per network;
126.96.36.199 All collocated FRM/FEM samplers must maintain a sample
frequency of at least 1 in 6 sample days;
188.8.131.52 Collocated FRM/FEM samplers shall be located at the
design value site, with the required FRM/FEM samplers deployed
among the largest MSA/CSA in the network, until all required
FRM/FEM are deployed; and
184.108.40.206 Data from collocated FRM/FEM are to be substituted for
any calendar quarter that an ARM method has incomplete data.
220.127.116.11 Collocation with an ARM under this part for purposes of
determining the coefficient of variation of the method shall be
conducted at a minimum of 7.5 percent of the sites with a minimum
of 1 per network. This is consistent with the requirements in
appendix A to this part for one-half of the required collocation of
FRM/FEM (15 percent) to be collocated with the same method.
18.104.22.168 Assessments of bias with an independent audit of the
total measurement system shall be conducted with the same frequency
as an FEM as identified in appendix A to this part.
2.4.5 Request for approval of a candidate ARM, that is not
already approved in another agency's network under this section,
must meet the general submittal requirements of section 2.7 of this
appendix. Requests for approval under this section when an ARM is
already approved in another agency's network are to be submitted to
the EPA Regional Administrator. Requests for approval under section
2.4 of this appendix must include the following requirements:
22.214.171.124 A clear and unique description of the site(s) at which
the candidate ARM will be used and tested, and a description of the
nature or character of the site and the particulate matter that is
expected to occur there.
126.96.36.199 A detailed description of the method and the nature of
the sampler or analyzer upon which it is based.
188.8.131.52 A brief statement of the reason or rationale for
requesting the approval.
184.108.40.206 A detailed description of the quality assurance
procedures that have been developed and that will be implemented
for the method.
220.127.116.11 A detailed description of the procedures for assessing
the precision and accuracy of the method that will be implemented
for reporting to AQS.
18.104.22.168 Test results from the comparability tests as required in
section 2.4.1 through 22.214.171.124 of this appendix.
126.96.36.199 Such further supplemental information as may be
necessary or helpful to support the required statements and test
2.4.6 Within 120 days after receiving a request for approval of
the use of an ARM at a particular site or network of sites under
section 2.4 of this appendix, the Administrator will approve or
disapprove the method by letter to the person or agency requesting
such approval. When appropriate for methods that are already
approved in another SLAMS network, the EPA Regional Administrator
has approval/disapproval authority. In either instance, additional
information may be requested to assist with the decision.
2.6 Use of Methods With Higher, Nonconforming Ranges in Certain
2.6.2 An analyzer may be used (indefinitely) on a range which
extends to concentrations higher than two times the upper limit
specified in table B-1 of part 53 of this chapter if:
188.8.131.52 The analyzer has more than one selectable range and has
been designated as a reference or equivalent method on at least one
of its ranges, or has been approved for use under section 2.5
(which applies to analyzers purchased before February 18,
184.108.40.206 The pollutant intended to be measured with the analyzer
is likely to occur in concentrations more than two times the upper
range limit specified in table B-1 of part 53 of this chapter in
the geographical area in which use of the analyzer is proposed;
220.127.116.11 The Administrator determines that the resolution of the
range or ranges for which approval is sought is adequate for its
intended use. For purposes of this section (2.6), “resolution”
means the ability of the analyzer to detect small changes in
2.6.3 Requests for approval under section 2.6.2 of this appendix
must meet the submittal requirements of section 2.7. Except as
provided in section 2.7.3 of this appendix, each request must
contain the information specified in section 2.7.2 in addition to
18.104.22.168 The range or ranges proposed to be used;
22.214.171.124 Test data, records, calculations, and test results as
specified in section 126.96.36.199 of this appendix for each range
proposed to be used;
188.8.131.52 An identification and description of the geographical
area in which use of the analyzer is proposed;
184.108.40.206 Data or other information demonstrating that the
pollutant intended to be measured with the analyzer is likely to
occur in concentrations more than two times the upper range limit
specified in table B-1 of part 53 of this chapter in the
geographical area in which use of the analyzer is proposed; and
220.127.116.11 Test data or other information demonstrating the
resolution of each proposed range that is broader than that
permitted by section 2.5 of this appendix.
2.6.4 Any person who has obtained approval of a request under
this section (2.6.2) shall assure that the analyzer for which
approval was obtained is used only in the geographical area
identified in the request and only while operated in the range or
ranges specified in the request.
2.7 Requests for Approval; Withdrawal of Approval.
2.7.1 Requests for approval under sections 2.4, 2.6.2, or 2.8 of
this appendix must be submitted to: Director, National Exposure
Research Laboratory (MD-D205-03), U.S. Environmental Protection
Agency, Research Triangle Park, North Carolina 27711. For ARM that
are already approved in another agency's network, subsequent
requests for approval under section 2.4 are to be submitted to the
applicable EPA Regional Administrator.
2.7.2 Except as provided in section 2.7.3 of this appendix, each
request must contain:
18.104.22.168 A statement identifying the analyzer (e.g., by serial
number) and the method of which the analyzer is representative
(e.g., by manufacturer and model number); and
22.214.171.124 Test data, records, calculations, and test results for
the analyzer (or the method of which the analyzer is
representative) as specified in subpart B, subpart C, or both (as
applicable) of part 53 of this chapter.
2.7.3 A request may concern more than one analyzer or
geographical area and may incorporate by reference any data or
other information known to EPA from one or more of the
126.96.36.199 An application for a reference or equivalent method
determination submitted to EPA for the method of which the analyzer
is representative, or testing conducted by the applicant or by EPA
in connection with such an application;
188.8.131.52 Testing of the method of which the analyzer is
representative at the initiative of the Administrator under § 53.7
of this chapter; or
184.108.40.206 A previous or concurrent request for approval submitted
to EPA under this section (2.7).
2.7.4 To the extent that such incorporation by reference
provides data or information required by this section (2.7) or by
sections 2.4, 2.5, or 2.6 of this appendix, independent data or
duplicative information need not be submitted.
2.7.5 After receiving a request under this section (2.7), the
Administrator may request such additional testing or information or
conduct such tests as may be necessary in his judgment for a
decision on the request.
2.7.6 If the Administrator determines, on the basis of any
available information, that any of the determinations or statements
on which approval of a request under this section was based are
invalid or no longer valid, or that the requirements of section
2.4, 2.5, or 2.6, as applicable, have not been met, he/she may
withdraw the approval after affording the person who obtained the
approval an opportunity to submit information and arguments
opposing such action.
2.8 Modifications of Methods by Users.
2.8.1 Except as otherwise provided in this section, no reference
method, equivalent method, or ARM may be used in a SLAMS network if
it has been modified in a manner that could significantly alter the
performance characteristics of the method without prior approval by
the Administrator. For purposes of this section, “alternative
method” means an analyzer, the use of which has been approved under
section 2.4, 2.5, or 2.6 of this appendix or some combination
2.8.2 Requests for approval under this section (2.8) must meet
the submittal requirements of sections 2.7.1 and 220.127.116.11 of this
2.8.3 Each request submitted under this section (2.8) must
18.104.22.168 A description, in such detail as may be appropriate, of
the desired modification;
22.214.171.124 A brief statement of the purpose(s) of the modification,
including any reasons for considering it necessary or
126.96.36.199 A brief statement of belief concerning the extent to
which the modification will or may affect the performance
characteristics of the method; and
188.8.131.52 Such further information as may be necessary to explain
and support the statements required by sections 184.108.40.206 and
2.8.4 The Administrator will approve or disapprove the
modification by letter to the person or agency requesting such
approval within 75 days after receiving a request for approval
under this section and any further information that the applicant
may be asked to provide.
2.8.5 A temporary modification that could alter the performance
characteristics of a reference, equivalent, or ARM may be made
without prior approval under this section if the method is not
functioning or is malfunctioning, provided that parts necessary for
repair in accordance with the applicable operation manual cannot be
obtained within 45 days. Unless such temporary modification is
later approved under section 2.8.4 of this appendix, the
temporarily modified method shall be repaired in accordance with
the applicable operation manual as quickly as practicable but in no
event later than 4 months after the temporary modification was
made, unless an extension of time is granted by the Administrator.
Unless and until the temporary modification is approved, air
quality data obtained with the method as temporarily modified must
be clearly identified as such when submitted in accordance with §
58.16 and must be accompanied by a report containing the
information specified in section 2.8.3 of this appendix. A request
that the Administrator approve a temporary modification may be
submitted in accordance with sections 2.8.1 through 2.8.4 of this
appendix. In such cases the request will be considered as if a
request for prior approval had been made.
2.9 Use of IMPROVE Samplers at a SLAMS Site. “IMPROVE” samplers
may be used in SLAMS for monitoring of regional background and
regional transport concentrations of fine particulate matter. The
IMPROVE samplers were developed for use in the Interagency
Monitoring of Protected Visual Environments (IMPROVE) network to
characterize all of the major components and many trace
constituents of the particulate matter that impair visibility in
Federal Class I Areas. Descriptions of the IMPROVE samplers and the
data they collect are available in references 4, 5, and 6 of this
2.10 Use of Pb-PM10 at SLAMS Sites.
2.10.1 The EPA Regional Administrator may approve the use of a
Pb-PM 10 FRM or Pb-PM 10 FEM sampler in lieu of a Pb-TSP sampler as
part of the network plan required under part 58.10(a)(4) in the
220.127.116.11 Pb-PM 10 samplers can be approved for use at the
non-source-oriented sites required under paragraph 4.5(b) of
Appendix D to part 58 if there is no existing monitoring data
indicating that the maximum arithmetic 3-month mean Pb
concentration (either Pb-TSP or Pb-PM 10) at the site was equal to
or greater than 0.10 micrograms per cubic meter during the previous
18.104.22.168 Pb-PM 10 samplers can be approved for use at
source-oriented sites required under paragraph 4.5(a) if the
monitoring agency can demonstrate (through modeling or historic
monitoring data from the last 3 years) that Pb concentrations
(either Pb-TSP or Pb-PM 10) will not equal or exceed 0.10
micrograms per cubic meter on an arithmetic 3-month mean and the
source is expected to emit a substantial majority of its Pb in the
fraction of PM with an aerodynamic diameter of less than or equal
to 10 micrometers.
2.10.2 The approval of a Pb-PM 10 sampler in lieu of a Pb-TSP
sampler as allowed for in paragraph 2.10.1 above will be revoked if
measured Pb-PM 10 concentrations equal or exceed 0.10 micrograms
per cubic meter on an arithmetic 3-month mean. Monitoring agencies
will have up to 6 months from the end of the 3-month period in
which the arithmetic 3-month Pb-PM 10 mean concentration equaled or
exceeded 0.10 micrograms per cubic meter to install and begin
operation of a Pb-TSP sampler at the site.
3.0 NCore Ambient Air Monitoring Stations
3.1 Methods employed in NCore multipollutant sites used to
measure SO2, CO, NO2, O3, PM 2.5, or PM 10-2.5 must be reference or
equivalent methods as defined in § 50.1 of this chapter, or an ARM
as defined in section 2.4 of this appendix, for any monitors
intended for comparison with applicable NAAQS.
3.2 If alternative SO2, CO, NO2, O3, PM 2.5, or PM 10-2.5
monitoring methodologies are proposed for monitors not intended for
NAAQS comparison, such techniques must be detailed in the network
description required by § 58.10 and subsequently approved by the
Administrator. Examples of locations that are not intended to be
compared to the NAAQS may be rural background and transport sites
or areas where the concentration of the pollutant is so low that it
would be more useful to operate a higher sensitivity method that is
not an FRM or FEM.
4.0 Photochemical Assessment Monitoring Stations (PAMS)
4.1 Methods used for O3 monitoring at PAMS must be automated
reference or equivalent methods as defined in § 50.1 of this
4.2 Methods used for NO, NO2 and NOX monitoring at PAMS should
be automated reference or equivalent methods as defined for NO2 in
§ 50.1 of this chapter. If alternative NO, NO2 or NOX monitoring
methodologies are proposed, such techniques must be detailed in the
network description required by § 58.10 and subsequently approved
by the Administrator.
4.3 Methods for meteorological measurements and speciated VOC
monitoring are included in the guidance provided in references 2
and 3 of this appendix. If alternative VOC monitoring methodology
(including the use of new or innovative technologies), which is not
included in the guidance, is proposed, it must be detailed in the
network description required by § 58.10 and subsequently approved
by the Administrator.
5.0 Particulate Matter Episode Monitoring
5.1 For short-term measurements of PM 10 during air pollution
episodes (see § 51.152 of this chapter) the measurement method must
5.1.1 Either the “Staggered PM 10” method or the “PM 10 Sampling
Over Short Sampling Times” method, both of which are based on the
reference method for PM 10 and are described in reference 1: or
5.1.2 Any other method for measuring PM 10:
22.214.171.124 Which has a measurement range or ranges appropriate to
accurately measure air pollution episode concentration of PM
126.96.36.199 Which has a sample period appropriate for short-term PM
10 measurements, and
188.8.131.52 For which a quantitative relationship to a reference or
equivalent method for PM 10 has been established at the use site.
Procedures for establishing a quantitative site-specific
relationship are contained in reference 1.
5.2 PM 10 methods other than the reference method are not
covered under the quality assessment requirements of appendix to
this part. Therefore, States must develop and implement their own
quality assessment procedures for those methods allowed under this
section 4. These quality assessment procedures should be similar or
analogous to those described in section 3 of appendix A to this
part for the PM 10 reference method.
1. Pelton, D. J. Guideline for Particulate Episode Monitoring
Methods, GEOMET Technologies, Inc., Rockville, MD. Prepared for
U.S. Environmental Protection Agency, Research Triangle Park, NC.
EPA Contract No. 68-02-3584. EPA 450/4-83-005. February 1983.
2. Technical Assistance Document For Sampling and Analysis of
Ozone Precursors. Atmospheric Research and Exposure Assessment
Laboratory, U.S. Environmental Protection Agency, Research Triangle
Park, NC 27711. EPA 600/8-91-215. October 1991.
3. Quality Assurance Handbook for Air Pollution Measurement
Systems: Volume IV. Meteorological Measurements. Atmospheric
Research and Exposure Assessment Laboratory, U.S. Environmental
Protection Agency, Research Triangle Park, NC 27711. EPA
600/4-90-0003. August 1989.
4. Eldred, R.A., Cahill, T.A., Wilkenson, L.K., et al.,
Measurements of fine particles and their chemical components in the
IMPROVE/NPS networks, in Transactions of the International
Specialty Conference on Visibility and Fine Particles, Air and
Waste Management Association: Pittsburgh, PA, 1990; pp.
5. Sisler, J.F., Huffman, D., and Latimer, D.A.; Spatial and
temporal patterns and the chemical composition of the haze in the
United States: An analysis of data from the IMPROVE network,
1988-1991, ISSN No. 0737-5253-26, National Park Service, Ft.
Collins, CO, 1993.
6. Eldred, R.A., Cahill, T.A., Pitchford, M., and Malm, W.C.;
IMPROVE - a new remote area particulate monitoring system for
visibility studies, Proceedings of the 81st Annual Meeting of the
Air Pollution Control Association, Dallas, Paper 88-54.3, 1988.
7. Data Quality Objectives (DQOs) for Relating Federal Reference
Method (FRM) and Continuous PM 2.5 Measurements to Report an Air
Quality Index (AQI). Office of Air Quality Planning and Standards,
U.S. Environmental Protection Agency, Research Triangle Park, NC
27711. EPA 454/B-02-2002. November 2002.
[71 FR 61313, Oct. 17, 2006, as amended at 73 FR 67061, Nov. 12,
2008; 75 FR 6534, Feb. 9, 2010]