_________________

__________________________________ 

Limited 2004-06 Speciation Data Derived from FRM 

 Filters for Twenty Areas

Neil Frank 

Office of Air Quality Planning and Standards 

September 18, 2008 

New speciation data are now available for PM2.5 design value monitoring sites in ten 

areas which EPA intends to designate nonattainment (NA) which previously have lacked 

speciation data. The ten areas are shown in the first table below. These states provided 

archived Federal Reference or Equivalent Method (FRM/FEM) Teflon filters to Desert 

Research Institute (DRI) in February-March of this year. EPA paid for the chemical 

analyses. Here is the link to the Teflon filter speciation data file. Data description, 

analytical protocols and other background information are presented below. While 

EPA’s preliminary judgment is that these new speciation data are helpful and generally 

confirm the designation proposals already made, EPA believes that they are not critical to 

the final determinations of NA area boundaries. The data and this explanation are being 

released via this document to facilitate State and public comment on the data and how 

they should be interpreted with respect to the designations process. 

Background 

NAAQS compliance or violation determinations are made only on the basis of 

FRM/FEM samplers. These PM2.5 samplers use a single Teflon filter to collect PM2.5. 

In normal operation, the Teflon filter is weighed before and after sampling, producing a 

measurement of the mass of the collected PM2.5 and from that a value for the 

concentration of PM2.5 mass in the air. As described in EPA’s Contributing Emission 

Score (CES)1

, knowledge of the species composition of ambient PM2.5 can be useful in 

understanding the types of emission sources that contribute to ambient PM2.5. These 

relative contributions in turn can help in understanding the specific geographic areas 

where the significantly contributing source may be, the appropriate boundaries for NA 

areas, and eventually the design of emission control programs to reduce PM2.5 

concentrations to reach attainment. The typical approach used to obtain this knowledge 

is to operate a separate multi-filter PM2.5 sampler, and subject the different filters to 

different types of chemical analysis aimed at quantifying different sets of chemical 

species. Because of the cost of doing so, such speciation samplers are not operated at all 

sites where FRM/FEM samplers operate. It has turned out that a number of FRM/FEM 

monitoring sites where there is no speciation sampler in operation are in violation of the 

24-hour PM2.5 NAAQS, and EPA has identified areas around those monitors which EPA 

intends to be designated as NA. When speciation data have not been available at the 

design value location, EPA and the States have had to estimate PM2.5 composition using 

 

1

 EPA’s Contributing Emission Score (CES), 

http://www.epa.gov/ttn/naaqs/pm/docs/tsd_ces_methodology.pdf. 
2

information from nearby monitors or other locations in the same geographical area. The 

latter is the speciation gap-filling approach presented in the CES.

While FRM/FEM Teflon filters normally are not chemically analyzed for PM2.5 species, 

it is possible to perform certain types of chemical analysis on them. In November 2007, 

EPA gave the State’s areas and sites without routine speciation monitoring the 

opportunity to provide their archived FRM/FEM Teflon filters to EPA for laboratory 

analysis to estimate the PM2.5 chemical constituents that can be determined from a 

Teflon filter. These new data were intended to assist EPA and the States with the 

identification of boundaries for potential NA areas and to also assist with development of 

future control strategies if the areas are designated as NA. 

A total of 20 areas in 12 States were identified for the investigation of chemical 

measurements from archived Teflon filters. These areas did not have chemical speciation 

samplers at the site which measured a violation of the 24-hr NAAQS using 2003-05 or 

2004-06 data. For each selected site, a list of 10 to 15 high PM2.5 filter days was 

identified. The proposed FRM/FEM filter days had PM2.5 concentrations greater than 

the annual 95th percentile of measured values from 2004, 2005 or 2006. EPA offered to 

pay for the chemical analysis and promised to share the data with the States. EPA 

arranged for DRI to provide the chemical analyses. A list of requested filters and the 

planned chemical analysis protocol was provided to the EPA Regional Offices for 

communication with their States. Monitoring agencies operating thirteen such monitoring 

locations in 10 States chose to submit their FRM/FEM filters to EPA. The initial list, 

participating locations and their Air Quality System (AQS) site codes follow. 
3

 

20 DV sites without collocated Chemical Speciation Network data 

proposed for new speciation analysis 

EPA region State County AQS Site 

3 PA Lehigh 420770004 

3 PA Mercer 420850100 

4 AL Etowah 010550010 * 

4 GA Muscogee 132150008 

5 IN Knox 180830004 

5 OH Trumbull 391550007 

5 WI Brown 550090005 

5 WI Milwaukee 550790043 

8 MT Ravalli 300810007 

8 UT Cache 490050004 * 

8 UT Salt Lake 490350003 * 

8 UT Weber 490570002 * 

9 AZ Santa Cruz 040230004 

9 CA Placer 060610006 

9 CA Solano 060950004 * 

9 CA Sutter 061010003 

10 ID Lemhi 160590004 * 

10 ID Shoshone 160790017 

10 OR Klamath 410350004 

10 OR Lane 410392013 * 

Monitoring agencies responsible for seven sites in 5 states either did not have archived 

filters or otherwise chose not to participate (indicated with *). 
4

Archived FRM/FEM filters from four additional locations with collocated Chemical 

Speciation Network (CSN) sites were also solicited. These locations were selected to 

represent a variety of PM2.5 compositions and different geographic regions. The 

speciation analyses of these additional filters were primarily intended to permit 

comparison with the routine measurements from the CSN and to assist with the 

interpretation and use of the filter analyses at the other archived filter locations. Several 

locations with high nitrate concentrations were specifically included to examine the 

comparability of measurements from archived Teflon filters with routine CSN sampling. 

A list of filter days was also selected from days with measured PM2.5 greater than the 

annual 95th percentile of measured FRM PM2.5 during 2004, 2005 or 2006. Of the four 

proposed collocated FRM/CSN locations, the responsible monitoring agencies for three 

sites chose to participate. These locations are listed below. One agency chose not to 

participate. 

EPA Region State County AQS Site Code 

5 OH Lucas 390950026 

5 WI Milwaukee 550790026 

8 UT Salt Lake 490353006 * 

9 CA Sacramento 060670010 

* Site did not submit filters to EPA for analysis 

The State filters provided to EPA were stored under refrigeration for all or part of the 

period between the sampling day and shipment to the DRI laboratory. This information is 

provided below for completeness and potential assistance in understanding the new data. 

EPA 

region State County City AQS Site Refrigeration 

3 PA Lehigh Allentown 420770004 1 year 

3 PA Mercer 420850100 1 year 

4 GA Muscogee Columbus 132150008 2 years 

5 IN Knox Vincennes 180830004 All 

5 * OH Lucas Toledo 390950026 Not all 

5 OH Trumbull Youngstown 391550007 All 

5 WI Brown Green Bay 550090005 All 

5 * WI Milwaukee Milwaukee 550790043 All 

8 MT Ravalli Hamilton 300810007 1 year 

9 AZ Santa Cruz Nogales 040230004 All 

9 CA Placer Roseville 060610006 All 

9 * CA Sacramento Sacramento 060670010 All 

9 CA Sutter Yolo City 061010003 All 

10 ID Shoshone Placerville 160790017 All 

10 OR Klamath 

Klamath 

Falls 410350004 1 year 

* Collocated with CSN site 
5

Analytical Procedures and Measurement Data 

An analytical protocol is described in Attachment 1 which is the Scope of Work provided 

to DRI. A combination of X-ray Florescence (XRF) to provide elemental concentrations 

(e. g., calcium, iron, sulfur, etc) and Ion Chromatography (IC) to estimate ions (sulfate, 

nitrate, potassium, ammonium, etc.) is described. The measured elemental 

concentrations allow the estimation of crustal material, other metallic oxides and tracers 

for specific source emission influences. The ion measurements allow the estimation of 

sulfate and nitrate mass which can be major components of PM2.5 mass. No 

measurements of elemental carbon or organic carbon were made as part of this project, as 

these carbon species cannot be measured on Teflon filters using the thermal optical 

procedures that are standard in the CSN. However, carbonaceous mass can be farily well 

estimated by material balance using estimated sulfate, nitrate and crustal mass with the 

SANDWICH method2

. For the three study sites with collocated CSN and FRM 

measurements, the CSN data presented below have been adjusted by SANDWICH 

methods to represent the composition that would have been measured by the FRM. 

These adjusted CSN data are available at www.epa.gov/airexplorer/. These adjustments 

to the CSN data are the same as made as part of EPA’s Contributing Emissions Score 

method for sites with CSN data. 

To allow for the possible loss of semi-volatile nitrate with XRF analysis, only half of the 

filters collected during the cooler months of October – April were subjected to XRF. 

This analytical procedure subjects the filters to a vacuum and high temperature, under 

which conditions nitrate can potentially evaporate. To explore the effect of XRF on 

nitrates, a subset of filters at the three comparison sites were subjected to XRF before IC.

3

 These data could be useful to guide future study of archived Teflon filters. 

Elemental carbon (EC) is nearly always only a small constituent of PM2.5 mass but can 

suggest potential influencing sources of the estimated total carbon component. To 

provide an indicator of elemental or black carbon, all of the Teflon filters were analyzed 

for filter transmittance using a densitometer.4

 This estimate of the darkness of the filter 

has previously been shown to be highly correlated with EC produced by thermal optical 

methods at a collocated speciation monitor 5. Such findings are also evident in this study 

from the comparison of darkness of the FRM/FEM filters from the three sites with CSN 

data and the actual EC measurement from the CSN sampler filter. However, no attempt 

has been made so far to use this correlation to estimate the amounts of EC on the Teflon 

filters at the 13 sites without CSN data. 

In the Teflon filter speciation data file, separate worksheets contain the data and 

definitions of data column headings and definitions of occasional data qualifiers. The 

PM2.5 mass concentration is also provided, as reported by the State. All of the chemical 

 

2 Frank, N. H., “Retained Nitrate, Hydrated Sulfates, and Carbonaceous Mass in Federal Reference Method 

Fine Particulate Matter for Six Eastern U.S. Cities,” J. Air & Waste Manage. Assoc. 2006, 56, 500-511. 3

 DRI uses a PanAnalytical unit for XRF. The level of XRF heating may be relevant in interpreting the 

nitrate results following XRF. 

4

 http://www.densitometers.net/transmission.asp 

5

 Watson J. G., and J. C. Chow, Comparison and evaluation of in situ and filter carbon measurements at the 

Fresno Supersite, J. Geophys. Res., 107 (D21), 8341, doi :10.1029/2001JD000573, 2002. 
6

data are in micrograms per cubic meter using the nominal sampler volume of 24 cubic 

meters and an assumed volume uncertainty of 2%. The mass DRI measured on the filters 

before and after XRF analysis is reported in micrograms per filter. This tab also includes 

some filters weighed again which did not get XRF. Worksheets are included for all the 

XRF data and, merely for convenience, also separately for a subset of 25 elements with 

higher detection limits and generally higher concentrations. 

Summary of New Findings. 

A summary of the estimated major components of PM2.5 is provided below. Based on 

the filter selection criteria, these averages are representative of the top 5 percent of 

measured PM2.5. The data in ug/m3 are organized by season: May-September (warm) 

and October-April (cool). The total number of analyzed filters and the number to which 

were subjected to IC and/or XRF is indicated. Sacramento, Toledo and Milwaukee site 

550790026 are the sites that are collocated with CSN monitors. Some of those filters 

received IC and XRF. 

State County AQS Site season

no. 

filters

no. 

IC

no. 

XRF

FRM 

mass Sulfate Nitrate TCM Crustal

AZ Santa Cruz 040230004 Cool 9 4 5 41.4 1.2 1.3 33.0 4.2

AZ Santa Cruz Warm 1 1 1 48.5 12.3 1.7 22.1 12.5

CA Placer 060610006 Cool 9 4 5 33.8 1.8 9.4 21.3 0.3

CA Placer Warm 1 1 1 47.0 3.5 0.1 43.3 0.2

CA Sacramento 060670010 Cool 12 12 6 39.2 3.5 16.8 18.2 0.9

CA Sutter 061010003 Cool 14 7 7 33.4 1.9 12.3 17.9 0.6

GA Muscogee 132150008 Cool 1 0 1 29.3 6.0 1.2

GA Muscogee Warm 7 7 7 33.8 22.7 0.1 10.5 0.6

ID Shoshone 160790017 Cool 16 8 8 38.5 0.7 0.8 35.4 0.2

IN Knox 180830004 Cool 4 2 2 32.0 10.1 9.4 6.7 0.3

IN Knox Warm 12 12 12 37.7 31.9 0.1 5.1 0.6

MT Ravalli 300810007 Cool 13 6 7 39.3 1.6 11.8 24.9 0.1

MT Ravalli Warm 1 1 1 22.5 0.8 0.1 20.7 0.9

OH Lucas 390950026 Cool 5 5 3 32.8 10.4 12.3 9.5 0.6

OH Lucas Warm 6 6 6 36.0 27.7 0.1 7.2 0.9

OH Trumbull 391550007 Cool 6 3 3 34.9 9.4 7.6 12.9 2.3

OH Trumbull Warm 10 10 10 33.7 27.1 0.1 5.8 0.8

OR Klamath 410350004 Cool 12 6 6 42.1 1.1 3.0 36.8 0.5

PA Lehigh 420770004 Cool 10 6 4 35.1 7.4 11.3 13.9 1.0

PA Lehigh Warm 12 12 12 36.5 28.2 0.1 7.5 0.6

PA Mercer 420850100 Cool 8 4 4 37.7 12.2 13.5 11.3 0.9

PA Mercer Warm 12 12 12 34.1 28.0 0.1 5.3 0.8

WI Brown 550090005 Cool 11 6 5 32.4 6.3 15.8 7.5 0.3

WI Brown Warm 2 2 2 49.6 23.2 0.2 25.8 0.5

WI Milwaukee 550790043 Cool 9 4 5 39.2 6.8 16.6 12.7 0.9

WI Milwaukee Warm 7 7 7 36.8 26.6 1.1 8.2 0.9

WI Milwaukee 550790026 Cool 7 7 4 38.1 9.7 14.3 13.6 0.6

WI Milwaukee Warm 5 5 5 36.3 27.7 0.2 7.5 0.9
7

Pie chart representations are provided in Figure 1. The sulfate and nitrate mass derived 

from the Teflon filter measurements were adjusted for particle bound water using an 

equation which approximates the Aerosol Inorganic Model (AIM) procedure used by 

SANDWICH. This polynomial equation and associated computational steps are presented 

in Attachment 2. For the pie charts presented here, the approximately 0.5 ug/m3 mass 

associated with the FRM filter blank is included in the denominator for purposes of 

computing pie chart percentages. 

Figure 1. Pie chart representations of the chemical composition of high day PM2.5 derived from 

archived Teflon filter measurements (subset of days > 95th percentile of measured PM2.5). 

SITE=Trumbull

 Teflon_Cool

5.63%

18.20%

45.09%

31.08%

 Teflon_Warm

2.28% 01

80.33%

17.18%

SITE=Brown

 Teflon_Cool

0.71%

44.89%

32.95% 21.45%

 Teflon_Warm

0.95%

0.38%

46.70%

51.97%

SITE=Lehigh

 Teflon_Cool

1.71%

29.58%

32.18%

36.52%

 Teflon_Warm

1.72% 039

77.24%

20.66%

SITE=Lehigh

 Teflon_Cool

1.71%

29.58%

32.18%

36.52%

 Teflon_Warm

1.72% 039

77.24%

20.66%

SITE=Toledo, OH

 Teflon_Cool

1.12%

37.83%

32.00%

29.05%

 Teflon_Warm

2.62% 038

76.94%

20.06%

SITE=Mercer

 Teflon_Cool

1.82%

26.93%

48.75%

22.50%

 Teflon_Warm

2.35% 023 81.97%

15.44%

SITE=Milwaukee-Waukesha-West Allis, WI

 Teflon_Cool

0.96%

37.69%

25.53%

35.83%

 Teflon_Warm

2.50% 048

76.30%

20.72%

Columbus GA

Green Bay, WI Milwaukee, WI Milwaukee, WI

Mercer Co, PA Youngstown, OH

Vincennes, IN Allentown, PA

Cool Warm CSN (non-DV) site

Toledo, OH

uscogee

 Teflon_Warm

1.7% 02

67.1%

31.1%

SITE=Milwaukee

 Teflon_Cool

2.44%

36.33%

33.46%

27.77%

 Teflon_Warm

2.41%

2.99% 72.25%

22.35%

Warm

SITE=Santa Cruz

 Teflon_Cool

12.32%

3.15% 6.53%

78.00%

 Teflon_Warm

25.78% 3.43%

25.31%

45.48%

SITE=Sacramento--Arde

 Teflon_Cool

1.16%

42.70%

9.04%

47.11%

Klamath Falls, OR Pinehurst, ID

Sacramento CA Placer Co, CA Yuba City CA

Nogales AZ

Cool Warm

Cool

CSN (non-DV) site

Cool

Cool Cool

Cool Warm

Ravalli, MT

Crustal Nitrate_mass Sulfate_mass TCM

SITE=Klamath

 Teflon_Cool

1.08%

6.92%

5.18%

86.83%

SITE=Placer

 Teflon_Cool

1.03%

26.58% 11.68%

60.71%

 Teflon_Warm

0.33%12

7.37%

92.17%

SITE=Ravalli

 Teflon_Cool

0.39%

28.75% 8.47%

62.39%

 Teflon_Warm

3.90%

0.47% 35

92.18%

SITE=Shosh

 Teflon_Cool

0.48%

2.14%

3.64%

93.75%

SITE=S

 Teflon_Cool

1.71%

34.60%

10.93%

52.76%
8

Comparisons with Collocated CSN data 

To help interpret the new data, comparison data for the three collocated FRM-CSN sites 

are provided below. First are scatter diagrams of sulfate ion and nitrate ion (with and 

without XRF), presented in Figure 2. The new measurements from the archived Teflon 

filters are shown on the vertical axis and the measurements from the routine CSN 

monitoring using a nylon filter are on the horizontal axis. The solid diagonal line is the 

1:1 line. 

 

Figure 2. Comparison of Teflon Nitrate and Teflon Sulfate with CSN ion measurements. 

S4IC

0

10

20

30

so4

0 10 20 30

CSN Sulfate (SO4=)

FRM Sulfate, ug/m3 (SO4=, Teflon)

1-1 line

T_SO4 Comparison of Teflon Sulfate with Nylon Sulfate from CSN

SITE Milwaukee-Waukesha-West Allis, W Sacramento--Arden-Arcade--Rosevi Toledo, OH

N3IC

0

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

16

17

18

19

20

no3

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20

0

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

16

17

18

19

20

SANDWICH adjusted Nitrate, NO3- (from CSN)

FRM Nitrate, ug/m3 (NO3-

,Teflon)

-1.5 ug/m3

- 3 ug/m3

Comparison of Teflon Nitrate with est. adjusted Nitrate from CSN

No XRF on Teflon before IC

(11 samples, cool season)

The other 24 samples, cool and warm
9

Next, a comparison of estimated sulfate, nitrate, crustal and total carbonaceous mass 

using the SANDWICH adjustments is presented in Figure 3. Note that the sulfate mass 

and nitrate mass panes in Figure 3 are based on the same data as shown in Figure 2, but 

are presented as sulfate and nitrate mass which include associated ammonium and 

particle bound water. The axes are also different than those in Figure 2 to permit the full 

range of the data to be visible. Also note that all four panes in Figure 3 use the same axes 

ranges (0 to 50 ug/m3), making it easier to put the magnitude of the four major PM2.5 

mass component concentrations into relative perspective. The points under the one-toone line for nitrate mass correspond to those measurements made after XRF. 

Figure 3. Major PM2.5 Mass components derived from FRM/FEM Teflon vs. collocated CSN 

measurements FRM Teflon, ug/m3

0

5

10

15

20

25

30

35

40

45

50

cr

0 5 10 15 20 25 30 35 40 45 50

SITE Milwaukee-Waukesha-West Allis, W Sacramento--Arden-Arcade--Rosevi Toledo, OH FRM Teflon, ug/m3

0

5

10

15

20

25

30

35

40

45

50

tcm

0 5 10 15 20 25 30 35 40 45 50

 FRM Teflon, ug/m3

0

5

10

15

20

25

30

35

40

45

50

nitrate

0 5 10 15 20 25 30 35 40 45 50

 FRM Teflon, ug/m3

0

5

10

15

20

25

30

35

40

45

50

sulfate

0 5 10 15 20 25 30 35 40 45 50

Major Mass Components Derived from Teflon vs. Collocated CSN Measurements

Sulfate mass Nitrate mass

Crustal TCM 

Horizontal axis represents 

PM2.5 components estimated from CSN data
10

Finally, pie chart comparisons of estimated PM2.5 composition using the new Teflon 

filter measurements and that using the routine CSN data are shown in Figure 4. Separate 

pies are shown for the cool and warm season data. The FRM derived nitrates in the cool 

season are lower in part because some of these filters received XRF prior to their ion 

analyses. This was also shown in Figure 3. 

Figure 4. Pie chart comparisons of PM2.5 composition derived from FRM/FEM Teflon and CSN 

measurements site=060670010

 CSN_Cool

1.67%

45.37%

5.72%

47.25%

 Teflon_Cool

2.21%

41.56%

6.06%

50.16%

site=390950026

 CSN_Cool

1.86%

41.31%

32.40% 24.44%

 CSN_Warm

5.29%

74.18%

20.53%

 Teflon_Cool

1.84%

37.42%

31.50%

29.23%

 Teflon_Warm

2.62%

0.38%

76.93%

20.07%

site=550790026

Crustal Nitrate_mass Sulfate_mass TCM

 CSN_Cool

2.38%

43.71%

25.97%

27.94%

 CSN_Warm

2.44%

74.27%

23.29%

 Teflon_Cool

1.66%

37.30%

25.11%

35.93%

 Teflon_Warm

2.50%

0.48%

76.26%

20.76%

Sacramento, CA

CSN

FRM

CSN

FRM

CSN

FRM

Toledo, OH

Milwaukee, WI
11

Attachment 1: Chemical Analysis of 412 Archived PM2.5 FRM Filters from State or 

Local agencies (Scope of Work with Desert Research Institute)

Project Purpose

The purpose of this project is to provide the Environmental Protection Agency (EPA) and State/local air 

officials information, otherwise unavailable, on the composition (or speciation) of ambient PM2.5 from 

monitoring sites and sampling days which are of relevance to attainment/nonattainment designations under 

the revised 24-hour PM2.5 NAAQS and/or to the development of emission source control strategies for 

areas which may be designated nonattainment. The data obtained from this project will be used to fill the 

current composition data gap for those areas without speciation monitors or without speciation at the site 

with the highest PM2.5 FRM mass. 

Knowing the composition of PM2.5 is relevant to designations because it can provide insights into the 

source types that have contributed to PM2.5 NAAQS violations, which in turn can provide insights into 

what geographic areas should be included in a nonattainment area on the basis of their contribution to the 

monitored violations. Similarly, knowing the composition of PM2.5 is relevant to the development of 

emission source control strategies for a designated nonattainment area because it can help identify the 

source types most usefully controlled and, indirectly, the geographic areas where controls should be 

applied. 

Approach

Teflon PM2.5 gravimetric mass filters from State/local monitoring sites without co-located speciation 

samplers, which have been kept refrigerated under State/local custody since the gravimetry, will be 

analyzed for ions, elements, and light absorption. Elemental carbon will be estimated based on the light 

absorption measurements. Organic carbon will be estimated, or at least bounded, through mass closure. 

A 48-filter method confirmation phase of this project will test the comparability of the results from 

analyses under this project with data from Chemical Speciation Network (CSN) sites, using filters from 

FRM sites that had collocated CSN sampling. (Adjustments will be made to CSN data using the 

SANDWICH technique by EPA to correct for known differences between FRM samplers/filters and CSN 

sampler/filters with respect to positive and negative sampling artifacts. See http://www.epa.gov/cgibin/htmSQL/mxplorer/query_spe.hsql and Frank, N. H., “Retained Nitrate, Hydrated Sulfates, and 

Carbonaceous Mass in Federal Reference Method Fine Particulate Matter for Six Eastern U.S. 

Cities,” J. Air & Waste Manage. Assoc. 2006, 56, 500-511. These collocated filters will be selected 

from days and sites which are appropriate for this comparability testing based on their season, geographic 

locale, and measured PM2.5 mass, but which are not of high interest for designations or control strategy 

development. This phase will check whether the storage and handling of the Teflon filters has altered their 

mass or composition. It will also allow the development, along with other available data, of a relationship 

between light absorption and elemental (black) carbon filter loading. 

Following verification of the methods to be used, approximately 394 field-collected filters obtained from 

state/local archives will be analyzed. Most of these PM2.5 Teflon filters have been selected from high PM2.5

concentration days primarily from NAAQS violating sites without co-located Chemical Speciation 

Network (CSN) or IMPROVE data. 

Background

EPA’s revised National Ambient Air Quality Standards for PM2.5 became effective on December 18, 2006. 

EPA retained the annual PM2.5 standards of 15 μg/m3 and revised the 24-hour PM2.5 standards, changing 

them from 65 μg/m3

 to 35 μg/m3.
12

The designation process for the revised 24-hour PM2.5 standards is the next step toward developing and 

implementing emission control programs for attaining and maintaining the revised standards. On June 8, 

2007, EPA issued guidance for states and tribes to use in identifying areas that meet or do not meet EPA’s 

recently revised national air quality standards for PM2.5 concentrations over a 24-hour period. 

(http://www.epa.gov/ttn/oarpg/t1/memoranda/meyers_memo060807.pdf) States and tribes are required to 

submit their initial recommendations to EPA by December 18, 2007. States and tribes will make their 

recommendations using the data for the years 2004 – 2006. EPA will review and consider those 

recommendations, and will notify states and tribes of any modifications EPA wishes to make to state or 

tribal recommendations. If new air quality data are available (e.g., PM2.5 mass for the year 2007 or 

speciation data for recent years), EPA will take these data into consideration when making final 

designations. The Clean Air Act requires EPA to complete the 

designation process within two years of the effective date of the standard unless the Administrator finds 

that additional information is needed to make these decisions. In such a case, EPA may take up to an 

additional year to make the designations, i.e., no later than three years after the effective date of the 

standard. 

When determining boundaries in urban areas for the annual PM2.5 standards several years ago, EPA applied 

a presumption that the boundaries for urban nonattainment areas should be based on metropolitan area 

boundaries as defined by the U.S. Office of Management and Budget. For the PM2.5 24-hour standards, 

EPA is establishing no such presumption. In developing boundary recommendations for nonattainment 

areas for the 24-hour PM2.5 standards, the June 8, 2007 guidance encourages states and tribes to evaluate 

each area on a case-by-case basis. For each monitor or group of monitors that indicate violations of the 

standard, nonattainment area boundaries should cover a sufficiently large area to include both the area that 

violates the standard and the areas that contribute to the violations. 

While many of the areas that experienced violations of the new 24-hour PM2.5 NAAQS in recent years have 

been operating PM2.5 speciation monitors that can provide composition information, of either the CSN or 

IMPROVE type or both, some of the areas lack such monitoring. EPA has identified 460 site-days from 

the latter areas that are of interest for this project. These 460 filters were collected in 20 counties in 12 

states from Regions 3, 4,5, 8, 9 and 10. EPA will contact monitoring officials in these areas for the purpose 

of obtaining access to archived filters from these site-days, and also access to associated data need for this 

project such as integrated sampler flow and filter tare and final weights. EPA will provide the contractor 

with a list of the target site-days and the contact information for the state/local officials who have agreed to 

coordinate the transfer of the filters and required associated data from the original field sampling operation. 

The participating States will provide a "field data" file that contains sample IDs, method code, sampling 

site code (includes state code, county code, and site ID) and address, sampling date and time, reported 

PM2.5 mass concentration, flow rate, flags, method code, and pollutant occurrence code (POC). EPA will 

also provide the exposed area (e.g. DRI uses 11.78 cm2 for Texas Teflon-membrane filter normalization). 

A minimum of three laboratory blanks (for pre-babs and for XRF analysis) will also be provided, 

preferably from the same batch for each State. For gravimetric analysis, the contractor will need to have 

the initial and post-weight comparison in mg/sample with corresponding IDs of each sample. 

 

Statement of Work

 From the selected filters, selected elemental contents will be obtained from: (1) more than half 

the filters using XRF; (2) more than half using ion chromatography ; (3) all filters using visible light 

transmission by densitometry. Note that some filters will get XRF analysis only; some filters will get IC 

analysis only; and the remaining filters will get both XRF and IC as described in the tasks below. The 

States will provide flow rates to permit the new Teflon filter chemical speciation measurements to be 

converted into ambient concentration values. Results of the analysis will be provided to the EPA and the 

States/Tribes by entry into the AQS system. 

Task 1 – Prepare of Work Plan 
13

The contractor shall prepare a simple work plan of sufficient detail to demonstrate understanding of and 

adequate plan for performing the remaining listed tasks in this Statement of Work, including any steps that 

are required for successful achievement of the stated objective but which are not stated explicitly in the 

descriptions of the remaining tasks 

The work plan shall include copies of the Standard Operating Procedures to be used for the ions, elements, 

and light absorption measurements. 

The work plan shall include copies of any associated data sheets or filter custody tracking form proposed to 

be used. 

The work plan shall include an estimated schedule for completion of all tasks. The plan may assume that 

the analyses required in Tasks 3 and 4 will be done in “batch mode” once all filters for each task have 

arrived. 

The Work Plan shall have adequate content to serve, along with other contractor documents referenced in 

the Work Plan, as a Quality Assurance Project Plan (QAPP) meeting the substance required of Tier X 

QAPPS under OAQPS’s tiered approach for such plans (add citation). 

Task 2 – Analyze Five Blank Filters

The contractor shall analyze a minimum of 3 standard blank Teflon filters to be provided by EPA for light 

absorption, elements, and ions to determine filter background levels for comparison to later field samples. 

This is also needed to properly interpret and make adjustments if any for the XRF and IC analyses. Also, if 

there is sufficient uniformity in light absorption for these blanks then an optical measurement using a 

photographer’s densitometer (Babs measurement) can be related to the EC filter loading via an absorption 

efficiency. 

For XRF, the suite of 24 elements listed in Table 1 shall be analyzed. 

The suite of three anions to be measured consists of chloride, nitrate and sulfate. 

The order of analysis of these blank filters will be light absorption, XRF, and ions. 

Deliverable: A written data report and recommendation as to whether the uniformity in the 

measurements on these blank filters is sufficient for the project to proceed to the remaining tasks. The 

report can be in the form of a memo to EPA. 

Task 3 – Obtain and Analyze 48 State/local Field-Collected Filters to Test the Validity of Methods, 

and Prepare Report

The contractor shall contact the identified state/local monitoring officials to arrange for appropriate 

packaging and pre-paid shipping of the 48 filters identified in attachment 1.1 as targets for this Task (not 

included in this document). 

For these 48 field samples, the following filter chemical analyses will be performed: 12 with XRF and IC, 

18 with XRF only, and 18 with IC only. Attachment 1.1 identifies which filters will have which chemical 

analyses. All 48 filters will have light absorption measurements made. The order of multiple analyses will 

be the same as in Task 2. 

To evaluate the impact of filter storage and filter transit on these 48 Teflon filters, gravimetry will be 

performed to compare with State derived FRM mass concentration. To judge the impact of XRF analysis 

on PM2.5 mass and potential loss of its volatile components, gravimetry will be performed a second time, 

after the XRF analyses. This information will be used is assessing the quality and interpretation of Task 3 

chemical analyses. 
14

The contractor shall calculate element and ion ambient concentrations for these filters, using the integrated 

sample flow obtained from the state/local monitoring officials. 

The contractor shall obtain from AQS the state/local-reported PM2.5 mass concentrations for these filters, 

and the full speciation concentration data for filters from the collocated CSN sites and days corresponding 

to these Teflon filters. 

The contractor shall develop a predictive relationship between the light absorption measurement (Babs) and 

filter elemental carbon loading (and ambient concentration, when integrated flow is included) based on 

these 48 filters and their corresponding CSN filters and on relevant other data collected by or known to the 

contractor. 

The contractor shall qualitatively and quantitatively assess the degree of agreement between its 

measurements of mass, elements, elemental carbon, and ions and the measurements originally reported to 

AQS. The SANDWICH adjusted CSN data, including reduced nitrate estimated to have been collected by 

the FRM will be used to assist with these comparisons. These data will be provided by EPA (These data are 

available at http://www.epa.gov/cgi-bin/htmSQL/mxplorer/query_spe.hsql.) The degree of uniformity 

between XRF elemental analysis, particularly for the components needed to estimate the crustal component 

(Al, Si, Fe, Ca and Ti), will be compared with collocated CSN measurements. Systematic causes of 

disagreement shall be investigated, e.g., that filters collected on days when ambient nitrate was absent in 

fact have nitrate present in the current analysis, that filters collected when nitrate was present appear to 

have more of a nitrate deficit compared to CSN filters than can be explained by SANDWICH concepts, etc. 

Deliverable: A data report on the analyses and on the qualitatively and quantitative assessment of the 

degree of agreement between the measurements, taking into account SANDWICH concepts and 

adjustments, with recommendations as to whether the degree of agreement justifies proceeding with Task 

4. This may be a memo style report. If the recommendation is to proceed, the report shall also include 

conclusions regarding the data quality likely to be achieved under Task 4 and caveats that should be 

included in any EPA dissemination of the data and findings from Task 4. The report shall also include any 

changes to the original Work Plan for Task 4 needed to increase the success of the project. 

Task 4 - Obtain and Analyze 394 State/local Field-Collected Filters, Prepare Memo style Report, and 

Submit Data to EPA

EPA shall contact the identified state/local monitoring officials to arrange for appropriate packaging and 

pre-paid shipping of the 394 filters identified in Attachment 1.1 as targets for this Task. Also, the EPA will 

obtain from these officials the reported PM2.5 mass concentration and any associated data that will be 

needed to complete calculations of concentrations that is not obtainable directly from AQS, such as the 

integrated filter air flow for the sample. EPA will provide this information to the contractor. 

For these 394 field samples, the following filter chemical analyses will be performed: 120 with XRF and 

IC, 244 with XRF only, and 244 with IC only. Attachment 1.1 identifies which filters will have which 

chemical analyses. All 394 filters will have light absorption measurements made. The order of multiple 

analyses will be the same as in Task 2. In general, filters collected on days expected to have high nitrate 

concentrations have been split about 50/50 between getting only IC and only XRF since if both 

measurements are made on the same filter the IC results for nitrates will be invalid due to the use of 

vacuum during the XRF analysis. Filters collected on days expected to have low nitrate will be subject to 

both XRF and IC analysis. 

The contractor shall calculate element and ion ambient concentrations for these filters, using the integrated 

sample flow obtained from the state/local monitoring officials. 

The contractor shall apply the predictive relationship between the light absorption measurement (Babs) and 

filter elemental carbon loading (and ambient concentration, when integrated flow is included) developed in 

Task 3 to all 394 filters to generate and estimate elemental ambient carbon concentrations for each. 
15

Using the PM2.5 mass, and elemental carbon concentration described above, the contractor will also 

estimate the organic carbon mass (OCM) by material balance. As described in Frank (2006), this 

represents an upper bound of OCM. 

Deliverables: 

A data report on the analyses and the estimates of ambient concentrations (a memo style report is 

sufficient). 

A qualitative report containing any gained insights into data quality and necessary caveats for its use. (a 

memo style report is sufficient). 

The contractor shall submit the Babs measurements and the concentration estimates for PM2.5 species for 

these 394 filters to EPA. EPA will arrange for the submittal of this data to AQS and will create any new 

method or parameter codes to correctly distinguish estimated concentrations from actually measured 

concentrations represented by standard AQS method and parameter codes. 
16

Attachment 2. 

EQUATION TO ESTIMATE PARTICLE BOUND WATER6

(replicates AIM7

 at FRM equilibration conditions) 

First, let D = NH4s / SO4, 0<D<0.375, where NH4s is the amount associated with SO4. 

i.e. NH4s=min (0.375*SO4, max(0,NH4-0.29*NO3) and where NO3 is the adjusted NO3 to 

represent the amount retained on an FRM filter. 

[The corresponding molar Degree of Neutralization (DON) varies from 0 to 2, i.e. up to 2 moles of 

NH4 are needed to fully neutralize the sulfate ion.] 

Next, define relative amounts of SO4, NO3 and NH4, where measured NH4 > 0 and is capped at a 

level to fully neutralize NO3 and SO4, i.e., NH4c=max ( (0.375*SO4+0.29*NO3), NH4). Units 

of SO4, NO3 and NH4 are ug/m3. 

Finally, define the following normalized parameters: 

S=SO4/(SO4+NO3+NH4c); 

N=NO3/(SO4+NO3+NH4c); 

and A=NH4/(SO4+NO3+NH4c). 

Then the amount of particle bound water (WATER) associated with measured SO4, adjusted NO3 

and measured NH4 is calculated according to the estimated degree of neutralization as follows:. 

 

High acidity: DON <1.2 (D < 0.225 ) 

WATER= [ 595.556 - 1440.585*S - 1126.488*N + 283.907*(S**1.5) - 13.384*(N**1.5) 

 - 1486.711*(A**1.5) + 764.229*(S**2) + 1501.999*(N * S) + 451.873*(N**2) 

 - 185.183*(S**2.5) - 375.984*(S**1.5) * N - 16.895*(S**3) - 65.814*(N**1.5)* S 

 + 96.825*(N**2.5) + 83.037*(N**1.5) *( S**1.5) - 4.419*(N**3) 

 + 1720.818*(A**1.5) * S + 1220.383*(A**1.5) * N - 311.496*(A**1.5) * (S**1.5) 

 + 148.771*(A**1.5) * (N**1.5) + 1151.648*(A**3)] * (SO4+NO3+NH4) 

Low acidity: DON>1.2 (D>0.225)

WATER= [ 202048.975 - 391494.647*S - 390912.147*N + 442.435*(S**1.5) - 

155.335*(N**1.5) - 293406.827*(A**1.5)+189277.519*(S**2)+377992.610*N*S 

+188636.790*N**2 - 447.123*S**2.5 -507.157*S**1.5*N -12.794*S**3 

+146.221*N**1.5*S +217.197*N**2.5 + 29.981*N**1.5*S**1.5 - 18.649*N**3 + 

216266.951*A**1.5*S + 215419.876*A**1.5*N - 621.843*A**1.5*S**1.5 

+239.132*A**1.5*N**1.5+95413.122*A**3] *(SO4+NO3+NH4) 

 

The above equations performs well with three decimal places (error < 3%). With two decimal 

places, error is -3 to +10 %. With one decimal, the low acidity equation has very high positive 

error. 

Regarding the notation for the above equations, * denotes multiplication and ** denotes 

exponentiation. 

 

 

6 This equation, developed by N. Frank is included in EPA Guidance on the Use of Models and Other 

Analyses for Demonstrating Attainment of Air Quality Goals for Ozone, PM2.5, and Regional Haze

http://www.epa.gov/scram001/guidance/guide/final-03-pm-rh-guidance.pdf 

7 Clegg, S.L.; Brimblecombe, P.; Wexler, A.S. Thermodynamic Model of the System H_-NH4 _-SO4 2--NO3 --H2O 

at Tropospheric Temperatures; J. Phys. Chem. 1998, 102, 2137-2154.