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Federal Register / Vol. 86, No. 183 / Friday, September 24, 2021 / Proposed Rules
Appendix N at each eligible monitoring site within the area. Data completeness requirements for a given year are met when at least 75 percent of the scheduled sampling days for each quarter have valid data.274
B. Monitoring Network Considerations Section 110a2Bi of the CAA
requires states to establish and operate air monitoring networks to compile data on ambient air quality for all criteria pollutants. The monitoring requirements are specified in 40 CFR
part 58. These requirements are applicable to state, and where delegated, local air monitoring agencies that operate criteria pollutant monitors. The regulations in 40 CFR part 58 establish specific requirements for operating air quality surveillance networks to measure ambient concentrations of PM2.5, including requirements for measurement methods, network design, quality assurance procedures, and in the case of large urban areas, the minimum number of monitoring sites designated as SLAMS.
In section 4.7 of Appendix D to 40
CFR part 58, the EPA specifies minimum monitoring requirements for PM2.5 to operate at SLAMS. SLAMS
produce data comparable to the NAAQS, and therefore, the monitor must be an approved federal reference method FRM, federal equivalent method FEM, or approved regional method ARM. The minimum number of SLAMS required is described in section 4.7.1 and can be met by either filter-based or continuous FRMs or FEMs. The monitoring regulations also provide that each core-based statistical area CBSA must operate a minimum number of PM2.5 continuous monitors; 275 however, this requirement can be met by either an FEM or a nonFEM continuous monitor, and the continuous monitors can be located with other SLAMS or at a different location. Consequently, the monitoring requirements for PM2.5 can be met with filter-based FRMs/FEMs, continuous FEMs, continuous non-FEMs, or a combination of monitors at each required SLAMS.
Under 40 CFR 58.10, states are required to submit annual monitoring network plans to the EPA.276 Within the San Joaquin Valley, CARB and the District are the agencies responsible for assuring that the area meets air quality monitoring requirements. CARB and SJVUAPCD submit monitoring network plans to the EPA annually. These plans 274 40

CFR part 50, Appendix N, section 4.2b.
CFR part 58, Appendix D, section 4.7.2.
276 40 CFR 58.10a1.
275 40

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describe and discuss the status of the air monitoring network, as required under 40 CFR 58.10. The EPA reviews these annual network plans for compliance with the applicable reporting requirements in 40 CFR part 58. With respect to PM2.5, we have found that the CARB and SJVUAPCD annual network plans meet the applicable requirements under 40 CFR part 58.277
During the 20182020 period, PM2.5
ambient concentration data that are eligible for use in determining whether an area has attained the PM2.5 NAAQS
were collected at a total of 18 sites within the San Joaquin Valley: 5 sites in Fresno County; 3 sites in Kern County;
2 sites each in Kings, Merced, San Joaquin, and Stanislaus counties; and 1
site each in Madera and Tulare counties.
The District operates 12 of these sites while CARB operates 6 of these sites.
All of the sites are designated SLAMS
for PM2.5.278 The primary monitors are FRMs at 5 of the 18 sites and beta attenuation monitor FEMs at 13 of the 18 sites. Overall, the Districts PM2.5
monitoring network meets, and in several Metropolitan Statistical Areas MSAs exceeds, the PM2.5 minimum monitoring requirements for the San Joaquin Valley.
Based on our review of the PM2.5
monitoring network as summarized above, we find that the monitoring network in the San Joaquin Valley is adequate for the purpose of collecting ambient PM2.5 concentration data for use in determining whether the San Joaquin Valley attained the 1997 24hour PM2.5 NAAQS by the December 31, 2020 attainment date.
277 Letter dated November 5, 2018, from Gwen Yoshimura, Manager, Air Quality Analysis Office, EPA Region IX, to Sheraz Gill, Deputy Air Pollution Control Office, SJVUAPCD; letter dated November 6, 2019, from Gwen Yoshimura, Manager, Air Quality Analysis Office, EPA Region IX, to Jon Klassen, Director of Strategies and Incentives, SJVUAPCD; letter dated October 26, 2020, from Gwen Yoshimura, Manager, Air Quality Analysis Office, EPA Region IX, to Jon Klassen, Director of Strategies and Incentives, SJVUAPCD; letter dated November 26, 2018, from Gwen Yoshimura, Manager, Air Quality Analysis Office, EPA Region IX, to Ravi Ramalingam, Chief, Consumer Products and Air Quality Assessment Branch, CARB; letter dated November 26, 2019, from Gwen Yoshimura, Manager, Air Quality Analysis Office, EPA Region IX, to Ravi Ramalingam, Chief, Consumer Products and Air Quality Assessment Branch, CARB; and letter dated November 5, 2020, from Gwen Yoshimura, Manager, Air Quality Analysis Office, EPA Region IX, to Ravi Ramalingam, Chief, Consumer Products and Air Quality Assessment Branch, CARB.
278 There are a number of other PM
2.5 monitoring sites within the valley, including other sites operated by the District, the National Park Service, and certain Indian tribes, but the data collected from these sites are non-regulatory and not eligible for use in determining whether the San Joaquin Valley has attained the PM2.5 NAAQS.

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C. Data Considerations and Proposed Determination Under 40 CFR 58.15, monitoring agencies must certify, on an annual basis, that data collected at all SLAMS
and at all FRM, FEM, and ARM SPM
stations meet the EPAs quality assurance requirements. In doing so, monitoring agencies must certify that the previous year of ambient concentration and quality assurance data are submitted to AQS and that the ambient concentration data are accurate.
CARB annually certifies that the data the agency submits to AQS are quality assured, including the data collected at monitoring sites in the San Joaquin Valley.279 SJVUAPCD does the same for data submitted to AQS from monitoring sites operated by the District.280
As noted above, CAA sections 179c1 and 188b2 require the EPA
to determine whether a PM2.5
nonattainment area attained the applicable PM2.5 NAAQS by the applicable attainment date, based on the areas air quality as of the attainment date. The SJV PM2.5 Plan includes a modeled demonstration of attainment by December 31, 2020, for the 1997 24hour PM2.5 NAAQS. Thus, the EPAs evaluation of whether the San Joaquin Valley PM2.5 nonattainment area has attained the 1997 24-hour PM2.5 NAAQS
is based on our review of the monitoring data recorded during the three years preceding the attainment date 2018
2020. Our review also takes into account the adequacy of the PM2.5
monitoring network in the nonattainment area and the reliability of the data collected by the network as discussed in the previous sections of this document.
With respect to data completeness, we determined that the data collected by CARB and the District meet the quarterly completeness criterion for all 12 quarters of the three-year period at most of the PM2.5 monitoring sites in the San Joaquin Valley. More specifically, among the 18 PM2.5 monitoring sites from which regulatory data are available, the data from 5 of the sites did not meet the 75 percent completeness criterion for each quarter; however, the data from all but 3 sites Fresno 279 For example, see letter dated June 21, 2021, from Sylvia Vanderspek, Chief, Air Quality Planning Branch, CARB, to Gwen Yoshimura, Manager, Air Quality Analysis Office, EPA Region 9, with enclosures, certifying calendar year 2020
ambient air quality data and quality assurance data.
280 For example, see letter dated June 22, 2021, from Jessica Olsen, Program Manager, SJVUAPCD, to Elizabeth Adams, Director, Air and Radiation Division, EPA Region IX, with attachments, certifying calendar year 2020 ambient air quality data and quality assurance data.

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