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APPENDIX C 

PM2.5 Continuous Monitor Comparability Assessment and Request 

for Waiver 

Introduction

The SCAQMD monitoring program has historically operated PM2.5 continuous monitors 

primarily to support forecasting and reporting of the Air Quality Index (AQI). These monitors 

supply data every hour to update the AQI on our web site as well as national web sites such as 

AIRNow (www.airnow.gov). SCAQMD has been using these monitors since the early part of the 

last decade as we implemented the PM2.5 monitoring program. Over the last few years, a 

number of PM2.5 continuous monitors have been approved as Federal Equivalent Methods 

(FEMs). By utilizing an approved FEM, any subsequent data produced from the method may be 

eligible for comparison to EPA’s health based standard known as the NAAQS. The primary 

advantage of operating a PM2.5 continuous FEM is that it can support the AQI, while also 

supplying data that are eligible for comparison to the NAAQS. Thus, a network utilizing PM2.5

continuous FEMs can potentially lower the number of filter-based FRMs operated in the 

network, which are primarily used for comparison to the NAAQS. These filter-based FRMs are 

resource intensive in that they require field operations as well as pre- and post-sampling 

laboratory analysis which results in data not being available for approximately 2-4 weeks after 

sample collection. 

The SCAQMD monitoring program has been evaluating PM2.5 continuous FEMs over the past 

several years. Although the PM2.5 continuous FEMs are automated methods, these methods still 

require careful attention in their set-up, operation, and validation of data. Once enough data was 

collected, we began to evaluate the performance of these methods compared to collocated FRMs. 

That evaluation is explained further below and includes our request regarding the use of the data 

from these methods. 

Request for Exclusion of PM2.5 Continuous FEM data from Comparison to the NAAQS 

The network technical requirements for requesting exclusion of data from comparison to the 

NAAQS are identified in 40 CFR §58.11(e). These requirements refer to the performance criteria 
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described in Table C-4 to subpart C of part 53. To accommodate the differences in how routine 

monitoring agencies operate their networks, several additional provisions are described in 

§58.11(e). When a topic is not addressed in §58.11(e), then the test specifications from table C-4 

applies. 

As shown in the Table below, the slope of the regression between collocated FRM and FEM 

measurements at the Anaheim, Central Los Angeles, North Long Beach, South Long Beach, and 

Rubidoux stations is higher than 1.1, which is outside the test specification indicated in §53 

Table C-4 (i.e. slope = 1 ± 0.1). Although the slope criteria was met, the intercept of the 

regression relationship between FRM and FEM data at the Burbank and Mira Loma monitoring 

sites does not meet the test specifications of between 15.05 - (17.32 × slope), but not less than -

2.0; and 15.05 - (13.20 × slope), but not more than +2.0 (also indicated in §53 Table C-4). 

Thus, in accordance with the PM NAAQS rule published on January 15th, 2013 (78 FR 3086) an
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d specific to the provisions detailed in §58.10 (b)(13) and §58.11 (e), SCAQMD is requesting 

that data from the all of the SCAQMD FEM PM2.5 monitors be set aside for comparison to the 

NAAQS. While SCAQMD is working to optimize the monitoring instrumentation to meet all of 

our monitoring objectives, the performance is not yet at a point where the comparability of the 

PM2.5 continuous FEMs operated in our network compared to collocated FRMs is acceptable. 

After assessing the comparability of the PM2.5 FEMs to the collocated FRMs for our network, 

the sites listed below do not meet the comparability requirements. Detailed one-page assessments 

from which the information described below was obtained are included at the end of this section. 
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Table – Request for Exclusion of PM2.5 Continuous FEM Data 

Site Name City Site ID Cont POC Cont Method Description 

PM2.5 

Cont 

Begin 

Date 

PM2.5 

Cont 

End 

Date 

Continuous/ 

FRM 

Sampler 

Pairs Per 

Season 

Slope 

(m) 

Intercept 

(y) 

Sites with PM2.5 continuous FEMs that are collocated with FRMs 

Anaheim Anaheim 06-059- 0007 3 Met-One BAM 1020 w/VSCC 01/01/ 2011 12/31/ 2013 

Winter = 247 

Spring = 254 

Summer = 227 

Fall = 260 

Total = 988 

1.16 2.62 

Burbank Burbank 06-037- 1002 3 Met-One BAM 1020 w/VSCC 01/01/ 2011 12/31/ 2013 

Winter = 259 

Spring = 217 

Summer = 262 

Fall = 250 

Total = 988 

1.10 4.47 

Central Los 

Angeles 

Los 

Angeles 

06-037-

1103 

3 Met-One BAM 1020 w/VSCC 01/01/ 2009 09/29/ 2011 

Winter = 226 

Spring = 161 

Summer = 170 

Fall = 182 

Total = 739 

1.21 1.77 

9 Met-One BAM 1020 w/VSCC 10/01/ 2011 12/31/ 2013 

Winter = 176 

Spring = 160 

Summer = 156 

Fall = 228 

Total = 720 

1.15 4.86 

North Long 

Beach 

Long 

Beach 

06-037-

4002 3 Met-One BAM 1020 w/VSCC 01/01/ 2011 12/31/ 2013 

Winter = 214 

Spring = 228 

Summer = 255 

Fall = 175 

Total = 872 

1.16 2.23 

South Long 

Beach 

Long 

Beach 

06-037-

4004 3 Met-One BAM 1020 w/VSCC 01/01/ 2012* 12/31/ 2013 

Winter = 128 

Spring = 169 

Summer = 134 

Fall = 121 

Total = 552 

1.27 0.35 
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Riverside/ 

Rubidoux Rubidoux 06-065- 8001 

3 Met-One BAM 1020 w/PM2.5 SCC 01/01/ 2010 01/31/ 2013 

Winter = 177 

Spring = 139 

Summer = 231 

Fall = 265 

Total = 812 

1.15 0.48 

9 Met-One BAM 1020 w/VSCC 08/02/ 2011 12/31/ 2013 

Winter = 170 

Spring = 152 

Summer = 212 

Fall = 265 

Total = 799 

1.12 2.26 

Mira Loma Mira Loma 06-065- 8005 3 Met-One BAM 1020 w/VSCC 01/01/ 2010 12/31/ 2013 

Winter = 255 

Spring = 244 

Summer = 257 

Fall = 265 

Total = 1021 

1.10 4.12 

*2011 data have not been submitted to AQS 
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Period of Exclusion of Data from the PM2.5 Continuous FEMs 

The above table details the period of available data by monitor on which the request to exclude 

PM2.5 continuous FEM data is based. Per EPA Regional Office approval, these data will be 

entered into EPA’s AQS database in a manner where the data are only used for the appropriate 

monitoring objective(s) (i.e., use data for just the AQI). Additionally, SCAQMD will continue to 

load any new data generated for the next 18 months (intended to represent the period until 

December 31 of 2015) in the same manner or until such time we request and receive approval 

from the EPA Regional Office to change the status of these monitors. 

PM2.5 Continuous FEM data for Reporting the AQI

While the analysis supports the request for the monitors above not be used for comparison to the 

NAAQS, the data are of sufficient comparability to collocated FRMs that they be used for public 

AQI reporting. Therefore, with EPA Regional Office approval we will report these data on our 

web site and to AIRNow (www.airnow.gov). As such, data submitted to EPA’s AQS database 

will be under “acceptable AQI” reporting (i.e., parameter code 88101) so that data users will 

know that these data are appropriate for use in AQI calculations, but not NAAQS comparison. 

Assessments

The following one-page assessments are locations where our agency has collocated PM2.5 FRM 

and continuous FEM monitors. Each of these assessments is represented in the “Table – 

Request for Exclusion of PM2.5 Continuous FEM Data” above. 
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Anaheim 

(FRM POC: 1; FEM POC: 3) 
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Burbank 

(FRM POC: 1; FEM POC: 3) 
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Central Los Angeles 

(FRM POC: 1; FEM POC: 3) 
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Central Los Angeles 

(FRM POC: 1; FEM POC: 9) 
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North Long Beach 

(FRM POC: 1; FEM POC: 3) 
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South Long Beach 

(FRM POC: 1; FEM POC: 3) 
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Rubidoux 

(FRM POC: 1; FEM POC: 3) 
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Rubidoux 

(FRM POC: 1; FEM POC: 9) 
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Mira Loma 

(FRM POC: 1; FEM POC: 3)