MEMORANDUM UNITED STATES ENVIRONMENTAL PROTECTION AGENCY RESEARCH TRIANGLE PARK, NC 27711

TO: DocketNo. EPA-R09-0AR-2014-0708 OFFICE OF AIR QUALITY PLANNING AND STANDARDS

CleanDataDetermination for 1997 PM2.5 Standards; California

- South Coast; Applicability ofClean Air Act Requirements
FROM: Richard A. Wayland,

# Director?~ ,4.

# tt/~ Air Quality Assessment Division, Office ofAir Quality Planning and Standards
SUBJECT: DataHandling for the Proposed CleanData Determination for the South Coast Air BasinNonattainment Area for the 1997 Annual and 24-hour PM2.5 National AmbientAir Quality Standards
The Environmental ProtectionAgency (EPA) is proposing a clean data determination for the South Coast Air BasinNonattainmentArea (Area) for the 1997 Annual and 24-hour PM2.5 National Ambient Air Quality Standards (NAAQS). EPA Region 9 proposes thatthe data used in this determinationhave followed the datahandling procedures in 40 CFR 50 Appendix N. While
we understandthat data from one monitoring site inthe Area, Pasadena (AQS ID: 06-037-2005), does not meetthe completeness requirements or the maximum quarterly value data substitution testprocedure discussed in40 CFR 50 AppendixN, Sections 4.1(d) and 4.2(d) further state that:

an annual [or 24-hour] PM2.5 NAAQS DV [design value] based on datathat do not meet the completeness criteria stated in 4(b) and also do not satisfy the test conditions specified in section 4(c), may also be considered valid withthe approval of, or atthe initiative of, the EPAAdministrator, who may consider factors such as monitoring site closures/moves, monitoring diligence, the consistency and levels ofthe daily values that
are·available, and nearby concentrations in determining whether to use such data. Therefore, EPARegion 9 has provided additional analysis ofthe data from the Pasadenamonitor to assess whetherthe data should be considered valid for the proposed attainment determination based on these additional criteria.
EPA Region 9 1reviewed the data collected bythe South Coast Air Quality Management District (SCAQMD) for the most recent three-year period (2011-2013) for completeness, and determined that the data collected from the Pasadena monitoring site is not eligible for the maximum

1 Analysis conducted by Michael Flagg, Air Quality Analysis Office, EPA Region 9

Internet Address (URL) • http://www.epa.gov Recycled/Recyclable • Printed wHh Vegetable Oil Based Inks on Recycled Paper (Minimum 25% Postconsumer)quarterly value data substitution test due to four quarters (quarter 1 2011, quarter 4 2012, quarter 12013 and quarter 2 2013) having less than 50% completeness. 40 CFR 50, Appendix N, Sections 4.1( c)(ii) and 4.2(c)(ii) both state that ifany quarter has less than 50% data capture then the substitutiontest cannot be used.
The Pasadena monitoring site had 47% completeness in quarter 1 2011 due to poor quality
assurance results and sampler operational issues, 47% completeness in quarter 4 2012 due to site repairs (i.e: SCAQMD was working to replace the monitoring site shelter from mid-November 2012 until the beginning ofJune 2013), 0% completeness in quarter 12013 due to site repairs, and 19% completeness in quarter 2 2013 due to site repairs. Additionally, quarter 3 2012 had 71% completeness due to multiple different sampler operational issues and site operator error. Per40 CFR 50, AppendixN, Sections 4.1(d) and 4.2(d), EPA Region 9 evaluated the location of the Pasadenamonitoring site relative to the historical design value site for the area, the historical annual and 24-hour PM2.5 design values trends overthe past 12 years at nearby monitoring sites, and causes·ofincomplete data when determining whether the 2011-2013 design value atthe Pasadenamonitoring site could be considered valid for the purposes ofthis action. First, the Pasadenamonitoring site is not located near the previous and current design value sites for the area. Historically, the Rubidoux (AQS ID: 06-065-8001) and the Mira Lorna (Van Buren) (AQS ID: 06-065-8005) monitoring sites have beenthe design value sites for the area for both the annual and 24-hour PM2.5 NAAQS. The Rubidoux monitoring site was the design value site for boththy annual and 24-hour PM2.5 NAAQS from 2001 to 2006, while the Mira Lorna (Van Buren) monitoring site was the design value site for boththe annual and 24-hour PM2.5 NAAQS from 2006 to 2013. The Pasadena monitoring site is located inthe center ofLos Angeles County, while the Rubidoux and Mira Lorna (Van Buren) monitoring sites are located approximately 38 miles to the east in Riverside County where higher values are typically measured. See Figure 1. Second, an assessment ofthe long term trends at the Pasadena monitoring site and nearby monitoring sites shows nearby sites have design values belowboththe annual and 24-hour 1997 PM2.5 NAAQS and the Pasadena monitoring site has the lowest design value compared to these nearby sites. See Figures 2 and 3. For example, during the 2001 to 2013 period, the Pasadena monitoring site has consistently measured lower design values for boththe annual and 24-hour PM2.5 NAAQS than the Azusa (AQD ID: 06-037-0002), Burbank (AQS ID: 06-037-1002), Pica Rivera (AQS ID: 06-037-1601), Pico Rivera #2 (AQS ID: 06-037-1602), and Los Angeles (Main St.) (AQS ID: 06-037-1103) monitoring sites, which are all located within an approximately 12 mile radius from the Pasadenamonitoring site. These four sites all have complete annual and 24- hour design values belowthe 1997 NAAQS for the 2011-2013 period and provide appropriate characterization ofair quality for the area surrounding the Pasadena monitoring site.
Based onthe location ofthe Pasadenamonitoring site, the historical design value concentrations relative to boththe annual and 24-hour 1997 PM2.5 NAAQS at the site and nearby locations, EPA Region 9 concluded that the PM2.5 data set for the 2011-2013 period from the Pasadena monitor should be considered valid for the proposed attainment determination. OAQPS agrees with this**a~sessment** and concurs that this data should be considered valid for the purposes ofthis proposed action.

### Figure 1

- South Coast Air Basin Nonattainment Area Monitor Locations

### Figure 2

– 1997 Annual PM2.5 NAAQS Design Value Trends

### Figure 3

- 1997 24

-Hour PM2.5 NAAQS Design Value Trends