UNITED STATES ENVIRONMENTAL PROTECTION AGENCY 

 WASHINGTON D.C. 20460 

 

OFFICE OF THE ADMINISTRATOR 

SCIENCE ADVISORY BOARD 

March 6, 2009 

EPA-CASAC-09-006 

The Honorable Lisa P. Jackson 

Administrator 

U.S. Environmental Protection Agency 

1200 Pennsylvania Avenue, N.W. 

Washington, D.C. 20460 

Subject: Consultation on Monitoring Issues Related to the NAAQS for Particulate Matter 

Dear Administrator Jackson: 

The Clean Air Scientific Advisory Committee (CASAC) Ambient Air Monitoring & Methods 

Subcommittee (AAMMS) held a public teleconference on February 11, 2009, to consult with staff from 

EPA’s Office of Air and Radiation (OAR) Office of Air Quality Planning and Standards (OAQPS) on 

issues related to monitoring and speciation sampling for coarse particles (PM10-2.5). When EPA issued the 

final rule to revise both the primary and secondary NAAQS for particulate matter (PM) in October 2006, 

a new Federal Reference Method (FRM) was also promulgated for measuring the mass concentration of 

PM10-2.5 in ambient air. As part of the revisions to the Ambient Air Monitoring Regulations, PM10-2.5

speciation monitoring will be required at National Core (NCore) multi-pollutant monitoring stations by 

January 1, 2011. 

The CASAC uses a consultation as mechanism for technical experts to provide comments to the 

Agency on the issues under consideration. Several areas of concern have been identified in the written 

comments provided by the individual Subcommittee members. They include (but are not limited to): the 

omission of organic compounds; the current lack of consensus on sampling and analytical methods for 

both PM10-2.5 and its speciated components; and the haste with which the Agency is committed to launch 

the PM10-2.5 monitoring network without sufficient time to analyze the data from the pilot study. As this is 

a consultation, we do not expect a formal response from the Agency. We thank the Agency for the 

opportunity to provide advice in the NAAQS review process. 

Sincerely, 

 /Signed/ 

Dr. Armistead (Ted) Russell, Chair 

CASAC AAMMS 

Enclosures 
2 2

Enclosure A 

U.S. Environmental Protection Agency 

Clean Air Scientific Advisory Committee 

Ambient Air Monitoring and Methods Subcommittee

CASAC MEMBERS 

Dr. Armistead (Ted) Russell (Chair), Professor, Department of Civil and Environmental 

Engineering, Georgia Institute of Technology, Atlanta, GA 

Dr. Donna Kenski, Data Analysis Director, Lake Michigan Air Directors Consortium, 

Rosemont, IL 

SUBCOMMITTEE MEMBERS 

Mr. George A. Allen, Senior Scientist, Northeast States for Coordinated Air Use Management 

(NESCAUM), Boston, MA 

Dr. Judith Chow, Research Professor, Desert Research Institute, Air Resources Laboratory, 

University of Nevada, Reno, NV 

Mr. Bart Croes, Chief, Research Division, California Air Resources Board, Sacramento, CA 

Dr. Kenneth Demerjian, Professor and Director, Atmospheric Sciences Research Center, State 

University of New York, Albany, NY 

Dr. Delbert Eatough, Professor of Chemistry, Department of Chemistry and Biochemistry , 

Brigham Young University, Provo, UT 

Dr. Eric Edgerton, President, Atmospheric Research & Analysis, Inc., Cary, NC 

Mr. Henry (Dirk) Felton, Research Scientist, Division of Air Resources, Bureau of Air Quality 

Surveillance, New York State Department of Environmental Conservation, Albany, NY 

Dr. Philip Hopke, Bayard D. Clarkson Distinguished Professor, Department of Chemical 

Engineering, Clarkson University, Potsdam, NY 

Dr. Rudolf Husar, Professor, Mechanical Engineering, Engineering and Applied Science, 

Washington University, St. Louis, MO 

Dr. Kazuhiko Ito, Assistant Professor, Department of Environmental Medicine, School of 

Medicine, New York University, Tuxedo, NY 
3 3

Dr. Thomas Lumley, Associate Professor, Biostatistics, School of Public Health and 

Community Medicine, University of Washington, Seattle, WA 

Dr. Peter H. McMurry, Professor and Head, Department of Mechanical Engineering, 

University of Minnesota, Minneapolis, MN 

Mr. Richard L. Poirot, Environmental Analyst, Air Pollution Control Division, Department of 

Environmental Conservation, Vermont Agency of Natural Resources, Waterbury, VT 

Dr. Kimberly A. Prather,* Professor, Department of Chemistry and Biochemistry, University 

of California, San Diego, La Jolla, CA 

Dr. Jay Turner, Visiting Professor, Crocker Nuclear Laboratory, University of California, 

Davis, CA 

Dr. Warren H. White, Research Professor, Crocker Nuclear Laboratory, University of 

California - Davis, Davis, CA 

Dr. Yousheng Zeng, Air Quality Services Director, Providence Engineering & Environmental 

Group LLC, Baton Rouge, LA 

Dr. Barbara Zielinska, Research Professor, Division of Atmospheric Sciences, Desert Research 

Institute, Reno, NV 

SCIENCE ADVISORY BOARD STAFF 

Ms. Kyndall Barry, Designated Federal Officer, 1200 Pennsylvania Avenue, N.W. (Mailcode 

1400F), Washington, DC, Phone: 202-343-9868, Fax: 202-233-0643, (barry.kyndall@epa.gov) 

*Dr. Prather did not participate in this CASAC AAMM Subcommittee activity.
4 4

Enclosure B 

Comments received:

Mr. George Allen .......................................................................................................................... 5 

Dr. Judith C. Chow..................................................................................................................... 10 

Mr. Bart Croes............................................................................................................................ 31 

Dr. Kenneth Demerjian.............................................................................................................. 35 

Dr. Delbert J. Eatough................................................................................................................ 38 

Mr. Dirk Felton........................................................................................................................... 48 

Dr. Philip Hopke ......................................................................................................................... 53 

Dr. Rudolf Husar ........................................................................................................................ 60 

Dr. Donna Kenski........................................................................................................................ 61 

Dr. Thomas Lumley.................................................................................................................... 63 

Dr. Peter H. McMurry................................................................................................................ 65 

Mr. Richard L. Poirot................................................................................................................. 69 

Dr. Jay R. Turner........................................................................................................................ 74 

Dr. Warren H. White.................................................................................................................. 78 

Dr. Yousheng Zeng ..................................................................................................................... 80 

Dr. Barbara Zielinska................................................................................................................. 81
5 5

Mr. George Allen 

PM10-2.5 Speciation Measurement

1. Table 1 provides a list of proposed PM10-2.5 species and analysis methods. Are there 

additional PM10-2.5 target species or methods that can be used to help identify the source of 

unidentified mass in order to obtain better mass closure? 

For all references to Table 1 in my revised comments, I am referring to the simpler version 

included with the EPA slide presentation, not Table 1 from the white paper. Other species: 

None that I am aware of; uncertainties in OC (estimated) mass measurements (there are many) 

may be part of the missing mass puzzle. Methods: ICPMS may be needed to get robust 

measurements of some of the listed acid/water soluble species at the range of concentrations 

expected from a dichotomous coarse channel filter. Ions could be done on quartz filter media 

(after punches are taken for carbon and protein analysis); if this is being considered, I would 

recommend that for the pilot study ions be done on both the Teflon and quartz filters to evaluate 

both and to provide a consistency check. 

2. Various sampling devices, including dichotomous samplers, MetOne SASS speciation 

monitors, PM10 and PM2.5 FRMs are potential sampling devices (with the appropriate filter 

types) for PM10-2.5 speciation. Among these sampler types, which should be included or excluded 

from the pilot network design? Are there other sampling devices not listed here that should be 

considered?

For PM-coarse, I strongly recommend using only a dichotomous (dichot) sampler (virtual 

impactor, VI) for coarse PM speciation sampling, since it has multiple advantages over a simple 

difference method (accuracy and precision, separation of pm-coarse from most of the pm-fine). 

The “classic” dichot VI combined with the existing low-volume PM10 inlet is a well 

characterized sampler. It is not an FRM or FEM for PM-coarse since there is no NAAQS for 

PM-coarse at this time. 

3. What are the PM10-2.5 speciation sampling artifacts that may be encountered using the 

samplers mentioned above and how should they be addressed? Is speciation by the difference 

method problematic for PM10-2.5 speciation and if so what specific issues make it problematic?

There are the usual fuzzy issues with OC artifacts, both positive and negative; we will probably 

have to live with these. The issue of how OC blanks will be created, handled, and applied to the 

data, and how samples are transported and stored (warm or cold) before analysis is important to 

clearly define. Nitrate in the coarse mode is complex -- there will be a mixture of ammonium 

nitrate and reaction products of nitric acid with alkaline crustal components. The latter may be 

more dominant. 

Speciation by difference is strongly discouraged. Any species that is primarily in the fine mode, 
6 6

such as sulfate, will be difficult to measure with useful precision by a difference method that is 

run routinely in SLT networks. This would be looking at a small difference between two large 

measurements, and measurement errors and biases get magnified dramatically when this is done. 

For a more detailed discussion of this topic, see: “Techniques for High-Quality Ambient Coarse 

Particle Mass Measurements”, George A. Allen, Jung-a Annie Oh, and Petros Koutrakis, Journal 

of the Air & Waste Management Association, Volume 49, September 1999, PM-133-141. 

While it is possible to generate highly precise PM-coarse mass data by difference under very 

carefully controlled “research-grade” conditions, routine networks are unlikely to provide this 

level of precision. Also, although the difference method can work well for PM when great care 

is taken to insure high precision, it remains unclear if analytical techniques for speciation can be 

made as precise as mass measurements without excessive cost in a routine network. 

4. The current and most widely used PM2.5 speciation sampler is the MetOne SASS and it has a 

flow rate of 6.7 Liters per minute (Lpm) which is significantly lower than either the FRM for 

PM10-2.5 mass or the dichotomous sampler (16.7 Lpm). If this sampler was configured for PM10-

2.5 by difference, would the 6.7 Lpm flow rate be problematic, especially with the need to 

compare reconstructed mass to the mass collected by the PM10-2.5 FRM?

Yes, this is likely to be problematic for many reasons. I do not recommend anything other than a 

16.7 Lpm dichotomous sampler for coarse pm speciation. 

5. Is the amount of particle mass collected on the dichotomous filters (especially the minor 

flow) sufficient for speciation chemical analysis?

Yes it is, for the “classic” dichot inlet flow of 16.7 Lpm. Note that although the coarse channel 

flow is only 1.67 Lpm, the coarse channel dichot filter includes (in theory) all the coarse particles 

present in the 16.7 inlet flow. Thus, the low flow for the coarse channel is not a relevant issue, 

and the comment on page 8 of EPA’s background document for this consultation about adequacy 

of XRF for dichot samples is not relevant. Another important parameter for evaluation of dichot 

performance is the filter diameter - it does not have to be 47 mm. The early dichots used 37 mm 

filters (33 mm exposed area). If enhanced loading is needed on the coarse channel, a 25 mm 

filter or a mask could be used; the coarse channel flow is low and large particles do not plug 

pores readily, so pressure drop should be minimal even with a much smaller filter diameter. 

There are loading-related issues with XRF and coarse particle analysis; self-absorption for large 

particles is a major issue and gets worse with high loading. 

One area that is still of potential concern is loss of particles from the dichot coarse mode filter 

during shipping. It should be clearly demonstrated that shipping does not cause mass loss; early 

work by Spengler and Thurston showed shipping loss with a 15 um inlet in the range of 30 to 

50% (Spengler and Thurston, JAPCA December 1983, 33:12; and Dzubay and Barbour, JAPCA

August 1983, 33:7). Higher losses would be expected from filters with a 15 um inlet cutpoint 

compared to 10 um. More recent work by Bob Vanderpool (EPA-ORD) did not show this loss 

using various shipping methods with one exception, where significant losses were observed. 
7 7

Dichot shipping loss tests done by Environment Canada in 2002 with a PM10 inlet showed 

losses ranging from 0 to 25 ug on a filter, but the actual filter loading was not reported and it is 

not clear if the original weighings were done before any shipping of the filters had occurred. My 

conclusion is that shipping can be an issue for coarse channel dichot filters; an established 

protocol that has been shown to not lose mass must be used. The Vanderpool work noted above 

can be used to establish a reasonable shipping protocol. 

PM10-2.5 Species or Components

1. Table 1 provides a list of proposed PM10-2.5 species and analysis methods. Among these 

species, which are most important? Are there important PM10-2.5 species or components missing 

from this list? Are there important analysis methods missing from this list?

Species priority: I agree with the order as listed in Table 1, with elements first, soluble ions 

second, then carbon and lastly bioaerosols. One aspect of pm-coarse speciation not on this list is 

particle surface composition. For coarse mode particles, the surface composition -- not the bulk 

mass composition -- may be much more relevant for health effects. For example: urban coarse 

mode particles are black, not earth colored, since they have a coating of soot (and things that 

absorb on soot...) on the surface (Figure 1 below, from Boston at a location approximately 100 

feet above street level, downtown). But by mass, EC would be very low. Thus, simple bulk 

mass measurements may not be that relevant for health effect studies. Methods for measurement 

of particle surface composition do exist, but may be expensive compared to traditional bulk 

chemical analysis. 

Figure 1. Deposit of particles greater than 2.5 um on an impactor surface in Boston. 
8 8

Finally, it may not be worth the added analytical expense to fully characterize carbonate carbon 

with a separate analysis. A TOA analysis time-temperature profile that goes higher than 580Chelium only can give a reasonably useful indication of carbonate carbon. Carbonate comes off as 

a sharp peak between 700-750 C, during the transition from 615 to 870 C, the highest helium 

only temperature used in the Sunset Labs laboratory carbon analyzer protocol. With some care, 

the modest amount of OC that comes off in this last helium only temperature step can be 

differentiated from carbonate, since the OC usually evolves off more slowly than carbonate. 

Also, it is important to get carbonate off at this time in the run profile, since otherwise it could be 

classified as EC; while this is not much of an issue for fine mode pm, it may be a major issue for 

coarse mode pm. 

2. In the consideration of potential ion measurements for PM10-2.5 species, what ions should be 

on the target list? Are nitrate or ammonium ions important? If so, is an acid gas denuder and 

nylon filter required for the proper collection of these species in PM10-2.5?

The ions listed are appropriate, with the exception of ammonium. Ammonium ion 

concentrations will be biased low in areas where nitrate is the major source of ammonium ion, as 

noted above. I do not consider ammonium ion by itself important enough to justify the extra 

effort needed to measure it correctly. 

3. The 2004 CD included a list of important PM10-2.5 components which included biological 

materials and fly ashes. If these species are important to characterize, what specific types of 

biological materials and fly ashes should be included? Is scanning electron microscopy (SEM) 

on Teflon filters sufficient to quantify and identify these species? Is the proposed total protein 

assay technique important to obtain a quantitative indicator of the total biological material 

present?

These species are at the bottom of my priority list. The analysis is expensive, and at least for 

bioaerosols, there is no way to control them. I wouldn’t expect a significant amount of fly ash in 

the coarse mode at most sites unless they are unusually impacted by a local source. 

4. Can the complication of particle size and absorption effects in XRF be resolved using 

absorption correction factors? If not, what other method(s) should be considered?

This may be a large problem for coarse pm speciation by difference, since PM10 loading will be 

larger than that on a pm-fine or pm-coarse dichot filter, and different [and imprecise] absorption 

correction factors would need to be used, resulting in additional coarse-mode by difference 

errors. Absorption correction factors are more practical for dichot filters. Still, ICPMS should 

be considered as an alternative analysis technique for acid/water soluble components since it is 

both more sensitive and does not have any issue with self-absorption. 

5. Are metal oxides a significant source of interference in thermal-optical analysis (TOA) of 

PM10-2.5 for OC and EC given the large expected soil component? If so, how should this 

interference be addressed?
9 9

Probably not. Metal oxides in crustal material can be sources of O2 or catalysts that can move 

the EC/OC split point in TOA analysis, but this does not necessarily mean the EC/OC split result 

is wrong -- it is just a limited amount of “pre-oxidation”. However, another potential issue with 

TOA is interference from biogenic coarse mode humic material; it may have some absorption of 

the ~660 nm wavelength used for pyrolysis correction. If biogenic mass is much greater than EC 

mass, the interference could be significant. 

Network Design

1. Are sites with high PM10 and low PM2.5 good candidate sites for PM10-2.5 speciation? Given 

that there will be some urban and rural NCore monitoring sites with PM10-2.5 speciation, what 

other factors should be considered in selecting the pilot monitoring and long-term sites or 

locations?

If a site’s PM10 is nearly all coarse-mode on a mass basis, it still may be useful to do dichotbased pm-coarse speciation. Some species of interest do not contribute much to the total PM 

mass. Pilot sites should be primarily in areas with large populations, to assist health effect 

studies. A subset in very large cities should be daily monitoring, since that is needed for health 

studies to properly account for any lag effect. 

2. If there is an opportunity to modify the NCore PM10-2.5 speciation monitoring requirements 

during a future rulemaking, should changes to the network design be considered? For example, 

changing the total number of required monitors and/or the required locations?

There are issues of large spatial gradients in urban pm-coarse; siting must be urban scale to be 

useful. It may be appropriate to have a second urban site (traffic oriented?) with at least limited 

speciation at mid-scale locations near sources of coarse PM. Results from the EPA-funded PMcoarse STAR grant projects on “Sources, Composition, and Health Effects of Coarse Particulate 

Matter” 

http://cfpub.epa.gov/ncer_abstracts/index.cfm/fuseaction/recipients.display/rfa_id/450/records_p

er_page/ALL or http://tinyurl.com/d65fcy will (with one exception) not be complete until after 

January 2011, but perhaps preliminary results from projects under this RFA may be able to 

inform network design. 

Finally, I am concerned about full deployment of this network before an appropriate pilot study 

period, including analysis of the data and method performance, is completed. Given the present 

status of the PM-coarse speciation program, I doubt that this can be done in time to have a full 

network in operation by January 2011. At the least another year, perhaps two years, is needed to 

prevent a premature deployment. Going forward with full network deployment before we are 

confident of what we can and should do for PM-coarse methods and species would be a massive 

waste of limited resources and is to be avoided if at all possible. 
10 10

Dr. Judith C. Chow 

PM10-2.5 Speciation Measurement

1. Table 1 provides a list of proposed PM10-2.5 species and analysis methods. Are there 

additional PM10-2.5 target species or methods that can be used to help identify the source of 

unidentified mass in order to obtain better mass closure? 

The Revised Table 1 provides a comprehensive list of elements, ions, carbon, and bioaerosol 

indicators. Additional PM10-2.5 species (e.g., filter light transmission [babs] and organic species) 

can be measured to assist in health assessment and for source attribution, but these additional 

marker species will not help to achieve better mass closure. It is not clear how the ORD report 

(U.S. EPA, 2006) found that 10–50% of the PM10-2.5 mass is unaccounted for. The sum of 

species is not a good indicator for PM10-2.5 mass closure calculations, since crustal material 

accounts for the major portion of PM10-2.5. A material balance that commonly groups by source 

types (e.g., geological material, secondary inorganic aerosols, carbon, salt, and others) may be a 

better way to evaluate mass closure. 

There are two major sources of uncertainties in PM10-2.5 mass closure calculations: 1) 

assumptions about the form of metal oxides present in the atmosphere, and 2) the multiplier used 

to convert OC to organic mass (OM). Oxides of major crustal components (Pettijohn, 1949) are 

used in the calculation for geological material. There are two commonly used metal oxide 

formulas that give similar estimates: 

 Geological Material = 1.89 × Al + 2.14 × Si + 1.4 × Ca + 1.43 × Fe (1) 

 Geological Material = 2.2 × Al + 2.49 × Si + 1.63 × Ca + 2.42 × Fe + 1.94 × Ti (2) 

 (Eq. 2 is the IMPROVE formula;Watson, 2002) 

Using OM = 1.2 × OC (and Eq. 1; Solomon et al., 1989), Chow et al. (2002a) found that 

geological material accounted for 72–81% of PM10-2.5, with 7–15% organics. The unidentified 

mass was negligible (<1%) at six urban locations in Mexico City. PM10-2.5 mass concentrations 

were high and variable, ranging from 19 to 56 μg/m3

. The nature of OM is expected to be 

different between PM2.5 and PM10-2.5. A 1.2 multiplier is appropriate for hydrocarbons or freshly 

emitted vehicle exhaust (composed mainly of H and C atoms), but humic-like substances 

(HULIS; Kerley and Jarvis, 1997; Schulten and Leinweber, 2000; Thomsen et al., 2002) and 

bioaerosols (Alexis et al., 2006; Bauer et al., 2008; Heinrich et al., 2003; Lee et al., 2007; 

Menetrez et al., 2007a) in PM10-2.5 probably justify a larger multiplier to account for unmeasured 

oxygen (O) and nitrogen (N) atoms. Elemental analysis of total H, C, N, O, and sulfur (S) may 

be applied in the pilot network to estimate OC/OM. These measurements can be compared with 

solvent extraction or other calculation methods (El Zanan et al., 2005; 2009). Mass closure 

within ±10–20% is considered sufficient as a quality check. 
11 11

2. Various sampling devices, including dichotomous samplers, MetOne SASS speciation 

monitors, PM10 and PM2.5 FRMs are potential sampling devices (with the appropriate filter 

types) for PM10-2.5 speciation. Among these sampler types, which should be included or excluded 

from the pilot network design? Are there other sampling devices not listed here that should be 

considered? 

Collocated BGI PQ2000 PM2.5 and PM10 samples have been designated as PM10-2.5 FRM 

(U.S.EPA, 2008). Nevertheless, all filter samplers with well-characterized PM2.5 and PM10 inlets 

should be considered. The PM10 sampling efficiency (Keywood et al., 1999; Watson et al., 1983; 

Wedding and Carney, 1983) is most important because the ambient size distribution often peaks 

near the 10 μm cut-point (Burton and Lundgren, 1987; Lundgren et al., 1984; Lundgren and 

Burton, 1995). Since PM10 and PM10-2.5 are highly variable in space and time (Baldauf et al., 

2002; Burton et al., 1996; Chow et al., 1981; 1992; 1999; 2000; 2002a), less expensive and 

portable samplers should be considered (e.g., the BGI OMNI and the Airmetrics MiniVol) to 

allow more of them to be deployed, especially for short-term studies. These 5 L/min units have 

well-characterized inlets. These filter samplers can be collocated with PM10-2.5 FRM. 

To detect short-duration events, optical particle counters (OPCs, e.g., Grimm Dust Monitor, TSI 

DRX DustTrak II) should also be considered. They can be comparable with filter measurements 

under certain circumstances (Grimm and Eatough, 2009; Grover et al., 2006; Peters et al., 2006; 

Teikari et al., 2003). Collocated TEOMs or BAMs with appropriate inlets are also useful for this 

purpose. 

Other low- and medium-volume sampling systems are still in use by different state and local 

agencies (e.g., Andersen RAAS, URG MASS, R&P2025 Partisol sequential PM2.5, and R&P 

2300 samplers). Sampling efficiencies should be estimated based on sampling effectiveness 

curves and anticipated size distributions at potential monitoring locations prior to conducting 

collocated sampler comparisons. It will be important to verify the homogeneity of PM10-2.5

levels across the sampling array (Mathai et al., 1990) using similar instruments for a valid 

comparison study. 

3. What are the PM10-2.5 speciation sampling artifacts that may be encountered using the 

samplers mentioned above and how should they be addressed? Is speciation by the difference 

method problematic for PM10-2.5 speciation and if so what specific issues make it problematic? 

Carbon gases are adsorbed onto quartz-fiber filters, and this artifact is imperfectly assessed and 

subtracted using field blanks exposed for the entire sample duration and backup filters (Arp et 

al., 2007; Chow et al., 2008; McDow, 1986; Noll and Birch, 2008; Watson et al., 2008; 2009). 

The magnitude of the gaseous organic sampling artifact correction is reduced by using higher 

sample volumes and lower filter exposed areas so that more carbon is collected per unit of filter 

area. A better understanding of the adsorbed compounds will be needed to go beyond current 

PM2.5 practices that can also be applied to PM10-2.5. 

Nitrate is less likely to evaporate from the coarse fraction as it does for PM2.5 (Ashbaugh and 

Eldred, 2004; Chow et al., 2002b; 2005). PM10-2.5 nitrate often occurs as non-volatile sodium 

nitrate (Mamane and Gottlieb, 1992; Mamane and Mehler, 1987; Wu and Okada, 1994). While 
12 12

there is abundant nitric acid in the atmosphere, it may react with alkaline PM10-2.5 (Goodman et 

al., 2000; Hodzic et al., 2006; Laskin et al., 2005; Ooki and Uematsu, 2005; Umann et al., 2005; 

Underwood et al., 2001), thereby resulting in a positive nitrate artifact for non-denuded samples 

at certain locations. 

Collocated PM10/PM2.5 samplers and virtual impactor (dichotomous) samplers require difference 

calculations for which the uncertainties of the individual samples should be propagated (Evans 

and Ryan, 1983; Watson et al., 2001). The propagated uncertainties of differences are about the 

same for collocated PM10/PM2.5 samplers, and may be higher for the dichotomous samplers 

because the 10 to 1 flow rate ratio between the fine and coarse channels often varies. As pointed 

out by Allen et al. (1999), variability in PM10-2.5 is expected to be higher either by virtual 

impactor or by the difference method than with an inertial impactor stage. Inertial impactors also 

have uncertainties due to particle bounce and non-uniform deposits. 

Most collocated sampling studies (see Chow, 1995; Chow et al., 2008 for study summaries) have 

compared PM2.5 and PM10 separately. PM10 comparisons are often poorer than those for PM2.5

when: 1) PM10-2.5 constitutes a large fraction of the PM10; 2) inlets have different sampling 

effectiveness curves (even minor ones); and 3) inlet sampling effectiveness changes with inlet 

loading.

4. The current and most widely used PM2.5 speciation sampler is the MetOne SASS and it has a 

flow rate of 6.7 Liters per minute (Lpm) which is significantly lower than either the FRM for 

PM10-2.5 mass or the dichotomous sampler (16.7 Lpm). If this sampler was configured for PM10-

2.5 by difference, would the 6.7 Lpm flow rate be problematic, especially with the need to 

compare reconstructed mass to the mass collected by the PM10-2.5 FRM? 

The MetOne SASS with a flow rate of 6.7 Lpm should be adequate to collect enough PM10-2.5 for 

analysis in urban networks when equipped with a 6.7 Lpm PM10 inlet (Kenny et al., 2000; Kenny 

and Gussman, 2000). The flow rates should be the same through all filters so that filter 

adsorption and evaporation artifacts would be similar. The URG 3000N sampler used in the 

current Chemical Speciation Network (CSN) for carbon analysis uses a flow rate of 22.7 Lpm, 

which is three times higher than the MetOne SASS. The tenfold difference in face velocity 

(107.2 cm/sec for the URG 3000N versus 9.5 cm/sec for the SASS) and its effect on sampling 

artifact needs to be further explored. This is more of a PM2.5 than a PM10-2.5 issue, however. The 

MetOne SASS filter holder is costly to obtain, process, and ship, and greater operational savings 

might be obtained by using a simpler sampler pair (e.g., BGI OMNI or PQ2000) that uses the 

standard Delron FRM filter ring. 

5. Is the amount of particle mass collected on the dichotomous filters (especially the minor 

flow) sufficient for speciation chemical analysis? 

Yes, the minor flow rate of 1.67 Lpm in the dichotomous sampler is not an issue, since PM10-.2.5

is taken from the 16.7 Lpm drawn through the PM10 inlet. The dichotomous sampler with either 

a PM15 or PM10 initial inlet has been used since the mid to late 1970s. The Harvard Six-City 

Study used elemental analysis by XRF on dichotomous sampler filters for health assessments 
13 13

(e.g., Ferris, Jr. et al., 1979; Spengler et al., 1983; Spengler and Thurston, 1983; Thurston and 

Spengler, 1985). 

During the early 1980s, dichotomous samplers (Beckman Instruments) were installed in the U.S. 

EPA’s Inhalable Particulate Matter network for PM2.5 and PM15 at 73 locations (Watson et al., 

1981). A subset of samples was submitted to elemental (Al, S, Cl, K, Ca, Ti, Mn, Fe, Ni, Cu, Zn, 

Br, Sn, and Pb) and ionic (NO3

-

, SO4

=

) speciation. The California Air Resources Board (ARB) 

also operated dichotomous (Andersen 244) samplers from 1983–2001 at 20 urban sites with 

elemental analysis for 30 species on both PM2.5 and PM10-2.5 samples (Motallebi et al., 2003a; 

2003b; 2003c). There are several previous studies using virtual impactors that have involved 

chemical speciation and used these data for air quality assessment (Dzubay et al., 1977; Dzubay, 

1980; Dzubay and Stevens, 1975; John et al., 1988; Li et al., 2001; Lin, 2002; Lin and Tai, 2001; 

Magliano, 1988; Mamane and Dzubay, 1990; Rashid and Griffiths, 1993; Sprovieri and Pirrone, 

2008; Watson et al., 1981; Witz et al., 1982). PM2.5 and PM10-2.5 mass and chemical data should 

be assembled and evaluated to better understand the nature and chemical composition of PM10-

2.5. 

For very low loading PM10-2.5 samples, the analytical instrument for XRF analysis and extraction 

volume for ion chromatography (IC) can be optimized to improve the minimum detectable limits 

(MDLs). 

PM10-2.5 Species or Components

1. Table 1 provides a list of proposed PM10-2.5 species and analysis methods. Among these 

species, which are most important? Are there important PM10-2.5 species or components missing 

from this list? Are there important analysis methods missing from this list? 

PM10-2.5 is enriched in soil-related elements (e.g., Al, Si, K, Ca, Ti, Mn, and Fe) at inland sites 

and marine-related elements (e.g., Na and Cl) at coastal sites (e.g., Chow et al., 1994a). Crustal 

elements, salt (Na and Cl), ions (e.g., NO3

-

) and carbon (e.g., OC and carbonate) are also 

important PM10-2.5 components to be considered. 

Without acidification for carbonate analysis, the presence of carbonate could bias both OC and 

EC measurements (Chow and Watson, 2002). Cao et al. (2005) found carbonate accounted for 

8% of PM2.5 mass during Asian dust storms, and ~5% between storms in Xian, China. Although 

PM2.5 carbonate may be negligible at non-urban IMPROVE sites (Chow and Watson, 2002), its 

abundances may be important in PM10-2.5 at some locations and it should be measured, especially 

for Asian dust intrusions (VanCuren, 2003; VanCuren and Cahill, 2002). 

Decomposition temperatures for various forms of carbonate vary according to the chemical and 

crystalline forms of the carbonate, catalytic influences of other materials, particle size, rate of 

heating, and the atmosphere surrounding the material being heated (Webb and Krüger, 1970). 

Figure A, adapted from Webb and Krüger (1970), shows differential thermal analysis (DTA) 

curves for various forms of carbonate. Different heating rates, shown in Figure B, also result in 

variations of DTA curves for magnesian limestone. Murray et al. (1951) found that the presence 

of salt altered the decomposition temperature of the first dolomite peak by -235 to 40 °C, as 
14 14

shown in Table A. 

Figure A. Differential Thermal Analyses (DTA) curves for: A) typical calcite (Faust, 1950); B) 

aragonite (Faust, 1950); C) natural calcite; D) sample giving curve C, calcined, hydrated, and 

partially recarbonated (from Webb and Krüger, 1970). 

Figure B. Differential Thermal Analyses (DTA) curves for magnesian limestone at a heating 

rate of: A) 15 °/min; and B) 5 °/min (from Webb and Krüger, 1970). 
15 15

Table A. Effects of salts on the “characteristic” temperature of the first dolomite peak (Murray 

et al., 1951, from Webb and Krüger, 1970). 

Organic carbon in urban and rural PM10 road dusts and agricultural soils ranges from 3–20% 

(Chow et al., 2003). There is growing evidence that coarse particle organic markers differ from 

those for PM2.5 and can be used to identify and quantify source contributions (Boon et al., 1998; 

Labban et al., 2006; Omar et al., 2002; Rogge et al., 2006; Rogge et al., 2007; Simoneit et al., 

2004; Song et al., 1999). Analyses for organic species (e.g., polycyclic aromatic hydrocarbons 

[PAHs]) should be considered on a subset of samples, possibly by thermal desorption-gas 

chromatography/mass spectrometry (TD-GC/MS) where only a small portion of quartz-fiber 

filters are needed to speciated non-polar organics (e.g., n-alkanes, alkenes, hopanes, steranes, 

PAHs; Chow et al., 2007; Hays and Lavrich, 2007; Ho et al., 2008; Ho and Yu, 2004; Yang et 

al., 2005) 

Coarse particles, especially minerals, have different light absorption characteristics at different 

wavelengths that can be used to distinguish among sources (Fialho et al., 2005; Kim et al., 2004). 

Filter light transmission (or babs) has been shown to be highly correlated with PM2.5 or PM10 EC 

and can serve as a surrogate for PM black carbon (BC). PM10-2.5 babs measurements at various 

wavelengths might be considered, especially for locations where only Teflon-membrane filter 

samples will be collected. 

2. In the consideration of potential ion measurements for PM10-2.5 species, what ions should be 

on the target list? Are nitrate or ammonium ions important? If so, is an acid gas denuder and 

nylon filter required for the proper collection of these species in PM10-2.5? 
16 16

The anions (i.e., Cl-

, NO3

-

, and SO4

=

) and cations (i.e., Na+, Ca++, K+, NH4

+

) listed in the revised 

Table 1 should all be measured. 

Coarse particle NO3

-

 (e.g., sodium nitrate [NaNO3]) has been found in the desert southwest and 

environments with abundant coarse PM (Mamane and Mehler, 1987; Watson et al., 1994). 

Chemical reactions convert sodium chloride (NaCl) to hydrochloric acid (HCl) and thermally 

stable NaNO3 (e.g., Ellis et al., 1983; Pilinis and Seinfeld, 1987; Russell and Cass, 1984). These 

reactions may dominate coarse particle NO3

-

 and occur when NaCl from sea salt, road sanding, 

or dry lake beds is an abundant atmospheric constituent. Since most of the PM10-2.5 contains 

alkaline crustal material, it is not necessary to use preceding acid gas denuders or nylon filters. 

Water-soluble Ca++, Mg+

, and PO4

3- are also found in coarse particles and may be indicative of 

sources. Water-soluble Ca+2 is formed by the reaction of acid gases with calcium carbonate 

(Krueger et al., 2004). 

Ion analysis is important for PM10-2.5, but it is unnecessary to allocate a separate nylon channel 

for sampling and analysis. If a URG3000N sampler is used for carbon analysis, a 47 mm quartzfiber filter should be used (with an exposed area of 11.8 cm2

) to allow for both carbon (0.5 cm2

punch) and ionic (1/2 of the 47 mm quartz-fiber filter) speciation. The current 25 mm filter 

configuration in the URG 3000N with an exposed area of 3.5 cm2 is not adequate for both carbon 

and ion speciation, especially if carbonate or other analyses are considered. 

3. The 2004 CD included a list of important PM10-2.5 components which included biological 

materials and fly ashes. If these species are important to characterize, what specific types of 

biological materials and fly ashes should be included? Is scanning electron microscopy (SEM) 

on Teflon filters sufficient to quantify and identify these species? Is the proposed total protein 

assay technique important to obtain a quantitative indicator of the total biological material 

present? 

Fly ash may be important if the sampling site is located near a coal-fired power plant or if there 

are fly ash storage piles nearby. Most modern industrial stacks have particle control devices that 

remove most of the coarse particles, and fugitive emissions are the most probable sources. 

Fugitive fly ash can be collected as grab samples, sieved, and resuspended in a laboratory 

resuspension chamber (Chow et al., 1994b) for both PM2.5 and PM10 size fractions, and 

submitted for the same chemical speciation as those for ambient PM. Resuspended fly ash 

samples may be useful for in vitro analysis in health assessment. Source profiles for fly ash can 

also be used in receptor modeling to estimate coal-fired power plant source contributions. 

Both optical and electron microscopy (SEM) can be applied to filter samples (Casuccio et al., 

1983; Edgerton et al., 2009; Gwaze et al., 2007; Kim, 2007; Ott et al., 2008; Watson et al., 2007; 

Zhao et al., 2006), but hundreds of particles must be classified to obtain quantitative results. 

Microscopy has the advantage of identifying unknown sources, but automated image recognition 

methods perform best with low particle densities (i.e., low flow rates of 1-2 Lpm) and a 

consistent background, such as that provided by flat polycarbonate filters; this implies a separate 

filter channel for microscopic analysis. 
17 17

Bioaerosols, including plant pollen and microorganisms (mold and bacteria) have been 

recognized as potential health hazards (e.g., Heederik, 2003; Schulze et al., 2006; Steerenberg et 

al., 2003; Targonski et al., 1995), but have not been widely studied (e.g., Heinrich et al., 2003; 

Menetrez et al., 2000; 2001; 2007b). If standard operating procedures (SOPs) can be established 

and target species determined, a subset of PM2.5 and PM10-2.5 samples (e.g., near agricultural 

fields, livestock, and vacant lands) should be analyzed for fungi, endotoxins, and proteins. 

5. Can the complication of particle size and absorption effects in XRF be resolved using 

absorption correction factors? If not, what other method(s) should be considered? 

Yes, corrections have been successfully devised and applied (Adams and Billiet, 1976; Adams 

and van Grieken, 1975; Berry et al., 1969; Criss, 1976; Dzubay and Nelson, 1975; Hunter and 

Rhodes, 1972; Jackson and Hampel, 1992; Rhodes and Hunter, 1972; Sewell et al., 1985; 

Wagman et al., 1978). Some further work is needed to compare the different approaches and 

evaluate deviations from basic assumptions (e.g., size distributions). The corrections are specific 

to the XRF configuration, so it would be good to develop a software system that could be used 

by different analysis laboratories. 

Self-absorption is most prominent for Al and Si, which have the least energetic absorption edges 

and emitted X-rays. Dzubay and Nelson (1975) showed that attenuation changes with 10 and 15 

μm particles as shown in Figure C. The derived attenuation factor is shown in Table B (Dzubay 

and Nelson, 1975) for their XRF set-up. 

Figure C. Attenuation factors for Kα X-rays of various elements calculated for four different 

coarse particle compositions (from Dzubay and Nelson, 1975). 
18 18

Table B. Midband attenuation and uncertainty for Kα X-ray fluorescence of various elements in 

coarse particles deduced from Figure C (from Dzubay and Nelson, 1975). 

ICP-MS presents its own difficulties in that Al, Si, and other elements are closely bound as 

oxides and need extreme acid digestion to free them for analysis (Anzano and Ruiz-Gil, 2005; 

Herner et al., 2006; Lu et al., 2003; Margui et al., 2005; Melaku et al., 2005). ICP-MS is not as 

precise as XRF for some key elements, including Si, P, S, and Cl, although it has lower detection 

limits for some of the transition metals. ICP-MS should be considered as complementary to, not 

as a replacement of, XRF. 

6. Are metal oxides a significant source of interference in thermal-optical analysis (TOA) of 

PM10-2.5 for OC and EC given the large expected soil component? If so, how should this 

interference be addressed? 

Metal oxides and catalysts such as NaCl, if present in significant amounts, could be a source of 

interference in thermal/optical analysis (Chow et al., 2001; 2006; Fung et al., 2004; Han et al., 

2007a; 2007b; Lin and Friedlander, 1988a; 1988b; 1988c). Several effects occur: 1) mineral 

oxides provide oxygen during the inert-atmosphere analysis phased (Fung and Wright, 1990); 2) 

the color of the minerals interferes with transmittance and reflectance corrections (Fung et al., 

2004); and 3) catalysts increase the EC oxidation rate (Lin and Friedlander, 1988a; 1988b). 

More systematic study is needed to quantify the uncertainties introduced by these effects and to 

determine thresholds below which they are tolerable. 

Network Design

1. Are sites with high PM10 and low PM2.5 good candidate sites for PM10-2.5 speciation? Given 

that there will be some urban and rural NCore monitoring sites with PM10-2.5 speciation, what 

other factors should be considered in selecting the pilot monitoring and long-term sites or 

locations? 

Sites with high PM10 and low PM2.5 (e.g., Las Vegas, NV, during spring; Chow et al., 1999) or 
19 19

low PM10 and high PM2.5 (e.g., wintertime in central California; Chow et al., 2005) are good 

candidates to test the high and low PM10-2.5 mass and composition, respectively. The PM2.5 Ca 

from CSN sites can be used to select sites with the potential for high carbonate concentrations. 

A combination of sites that are influenced by paved and unpaved roads, agricultural activities, 

storage piles, and bioaerosols are ideal for pilot and long-term monitoring to assess the impacts 

from specific sources. 

2. If there is an opportunity to modify the NCore PM10-2.5 speciation monitoring requirements 

during a future rulemaking, should changes to the network design be considered? For example, 

changing the total number of required monitors and/or the required locations? 

While there is a desire to collocate PM10 and PM2.5 at sites for source attribution and for 

assessment of health impacts, this may be an opportunity to modify the NCore sites to 

accommodate special needs of more source-oriented PM10-2.5 sites. 

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31 31

Mr. Bart Croes 

These comments also reflect input from California Air Resources Board (ARB) staff responsible 

for implementing U.S. EPA monitoring requirements and using the data in source apportionment 

and health studies. 

PM10-2.5 Speciation Measurement

1. Table 1 provides a list of proposed PM10-2.5 species and analysis methods. Are there 

additional PM10-2.5 target species or methods that can be used to help identify the source of 

unidentified mass in order to obtain better mass closure? 

Not that I am aware. 

2. Various sampling devices, including dichotomous samplers, MetOne SASS speciation 

monitors, PM10 and PM2.5 FRMs are potential sampling devices (with the appropriate filter 

types) for PM10-2.5 speciation. Among these sampler types, which should be included or excluded 

from the pilot network design? Are there other sampling devices not listed here that should be 

considered? 

A dichotomous sampler would be a superior choice. While California has dismantled its 20-site 

network that operated from 1983 to 2001 (due to resource constraints once the PM2.5 FRM 

network was deployed), the data are in reasonable agreement for PM2.5 and PM10 (Motallebi, et 

al., 2003a) which has allowed us to determine long-term PM trends (Motallebi, et al., 2003b) and 

perform particle pollution assessments in areas of California that exceed state and federal 

ambient air quality standards (Motallebi, 1999; Motallebi and Dolislager, 1999; Motallebi, et al., 

2003bc). 

I understand the concerns expressed by Delbert Eatough and Peter McMurry, but PM-coarse 

speciation by difference should also be considered. The approach is to continue use of the 

MetOne SASS sampler with a 2.5-μm cut point for ions and metals, add a 10-μm cut point for 

ions and metals, and calculate PM-coarse species by difference. Even though the flow is lower 

(6.7 Lpm) we have found in the California network that we always have sufficient material for 

accurate analyses (few species < LOD), although that may not be the case for other parts of the 

country. This approach is economical because the standard SASS has three flow controlled 

channels and two orifice channels. To implement this proposal would be to upgrade one orifice 

channel to active flow control. 

Total, organic and elemental carbon is sampled by the URG 3000N for PM2.5. To implement the 

carbon speciation by difference would require a second URG with a 10-μm cut point. 

3. What are the PM10-2.5 speciation sampling artifacts that may be encountered using the 

samplers mentioned above and how should they be addressed? Is speciation by the difference 

method problematic for PM10-2.5 speciation and if so what specific issues make it problematic? 
32 32

Any potential artifacts would be consistent with the PM2.5 speciation program per the difference 

approach described above. 

4. The current and most widely used PM2.5 speciation sampler is the MetOne SASS and it has 

a flow rate of 6.7 Liters per minute (Lpm) which is significantly lower than either the FRM for 

PM10-2.5 mass or the dichotomous sampler (16.7 Lpm). If this sampler was configured for 

PM10-2.5 by difference, would the 6.7 Lpm flow rate be problematic, especially with the need to 

compare reconstructed mass to the mass collected by the PM10-2.5 FRM? 

In California, it has not been problematic with the PM2.5 speciation program except with 

elemental carbon, which has been switched to the URG 3000N sampler. We’ve found measured 

SASS mass compares well with measured FRM mass. 

5. Is the amount of particle mass collected on the dichotomous filters (especially the minor 

flow) sufficient for speciation chemical analysis? 

Yes, California has an extensive dataset that confirms there is sufficient mass for trace metal 

speciation (Motallebi, et al., 2003a). 

PM10-2.5 Species or Components 

1. Table 1 provides a list of proposed PM10-2.5 species and analysis methods. Among these 

species, which are most important? Are there important PM10-2.5 species or components 

missing from this list? Are there important analysis methods missing from this list? 

Even though it’s not explicitly mentioned, I assume sulfur will be included in the elemental 

analyses (at minimum it provides a cross check of sulfate ion by IC). 

2. In the consideration of potential ion measurements for PM10-2.5 species, what ions should be 

on the target list? Are nitrate or ammonium ions important? If so, is an acid gas denuder and 

nylon filter required for the proper collection of these species in PM10-2.5? 

Nitrate and ammonium are always important. At least in Los Angeles, coarse particle nitrate 

appears to be significant, but it is usually in the form of sodium nitrate. 

3. The 2004 CD included a list of important PM10-2.5 components which included biological 

materials and fly ashes. If these species are important to characterize, what specific types of 

biological materials and fly ashes should be included? Is scanning electron microscopy (SEM) 

on Teflon filters sufficient to quantify and identify these species? Is the proposed total protein 

assay technique important to obtain a quantitative indicator of the total biological material 

present? 

I defer to others. 
33 33

4. Can the complication of particle size and absorption effects in XRF be resolved using 

absorption correction factors? If not, what other method(s) should be considered? 

I defer to others, but we understand these correction factors to be theoretical and crude and that 

there is no consensus on their use. In California, we do not use any correction factors for PM2.5

elemental analyses. We understand that at most these correction factors would be no greater than 

10%, and possibly inconsequential. 

5. Are metal oxides a significant source of interference in thermal-optical analysis (TOA) of 

PM10-2.5 for OC and EC given the large expected soil component? If so, how should this 

interference be addressed? 

I defer to others. 

Network Design

1. Are sites with high PM10 and low PM2.5 good candidate sites for PM10-2.5 speciation? Given 

that there will be some urban and rural NCore monitoring sites with PM10-2.5 speciation, what 

other factors should be considered in selecting the pilot monitoring and long-term sites or 

locations? 

Sites with high PM10 and low PM2.5 suggest areas dominated by wind blown dust. If the source 

is obvious for a particular site, I question the value (and diversion of resources) for investigating 

an air quality issue that may already be well understood. Because of higher deposition rates for 

coarse particles, a PM10-2.5 monitoring site is representative of sources relatively nearby, so it 

should be obvious if a single source (e.g., windblown dust, coal pile, tire and brake wear) is 

predominant. 

The pilot monitoring study should include a southern California site that is high in both PM10 and 

PM2.5 with potential for significant coarse particle contributions from sources other than windblown dust, such as coarse particle nitrate. Other sites for pilot studies and long-term monitoring 

can be selected based on an analysis of existing PM10 and PM2.5 network data to identify areas 

(using the difference method) that are high in both PM10-2.5 and PM2.5. 

2. If there is an opportunity to modify the NCore PM10-2.5 speciation monitoring requirements 

during a future rulemaking, should changes to the network design be considered? For example, 

changing the total number of required monitors and/or the required locations? 

The Health Effects Institute or other representations of the air pollution epidemiology 

community should be consulted as to where year-round PM-coarse measurements would be 

useful for epidemiologic cohort studies. Otherwise, I agree with USEPA staff that the candidate 

NCore site may not be the best choice for PM10-2.5 speciation since the highest concentrations of 

PM2.5 and PM10-2.5 are usually not collocated. A study by ARB staff (VanCuren, 1999) concludes 
34 34

that, in winter, most coarse (PM10-2.5) particles collected are less than 2 hours old, and even on 

days that are not truly “stagnant,” samplers are very strongly influenced by their immediate 

surroundings (distances less than 10 km), and only weakly influenced by regional emissions. The 

implications for interpretation of sample analyses are as follows: (1) Typical PM sampling 

networks are unlikely to represent regional conditions; (2) Similarity of samples in time and 

space between widely separated samplers probably arises from sampling analogous local 

environments rather than a uniformly mixed regional air mass; (3) Even weak sources near a 

sampler will prevent regionally representative samples, so that “background” specification in 

models can be strongly skewed by misapplication of sampler data; (4) Source-receptor 

relationships within a single modeling grid cell can cause measured and modeled source impacts 

at a sampler to diverge by orders of magnitude, even for grid cells as small as 1 km; and (5) 

Differential deposition of coarse and fine particles will skew source apportionment by chemical 

tracers unless the tracers and the source emissions have the same size distribution. 

VanCuren, T. (1999) Spatial Factors Influencing Winter Primary Particle Sampling and 

Interpretation. J. Air Waste Manage. Assoc., 49: PM-3-15. 

Motallebi, N. (1999) Wintertime PM2.5 and PM10 Source Apportionment at Sacramento, 

California. J. Air Waste Manage. Assoc., 49: PM-25-34. 

Motallebi, N. and L. J. Dolislager (1999) Characterization of Particulate Matter in California. J. 

Air Waste Manage. Assoc., 49: PM-45-56. 

Motallebi, N., C. A. Taylor, Jr., K. Turkiewicz, and B. E. Croes (2003a) Particulate matter in 

California: Part 1 – Intercomparison of several PM2.5, PM10-25, and PM10 monitoring 

networks. J. Air Waste Manage. Assoc., 53: 1509-1516. 

Motallebi, N., C. A. Taylor, Jr., and B. E. Croes (2003b) Particulate matter in California: Part 2 

– Spatial, temporal, and compositional patterns of PM2.5, PM10-25, and PM10. J. Air 

Waste Manage. Assoc., 53: 1517-1530. 

Motallebi, N., H. Tran, B. E. Croes, and L. C. Larsen (2003c) Day-of-week patterns of PM and 

its chemical components at selected sites in California. J. Air Waste Manage. Assoc., 53:

867-888. 
35 35

Dr. Kenneth Demerjian 

PM10-2.5 Speciation Measurement

1. Table 1 provides a list of proposed PM10-2.5 species and analysis methods. Are there 

additional PM10-2.5 target species or methods that can be used to help identify the source of 

unidentified mass in order to obtain better mass closure? 

See items 2 and 3 below. 

2. Various sampling devices, including dichotomous samplers, MetOne SASS speciation 

monitors, PM10 and PM2.5 FRMs are potential sampling devices (with the appropriate filter 

types) for PM10-2.5 speciation. Among these sampler types, which should be included or excluded 

from the pilot network design? Are there other sampling devices not listed here that should be 

considered? 

Run two (2) EC – OC semi-continuous (hourly average) measurements outfitted with PM10 and 

PM2.5 inlets respectively. Although this measurement is not totally free of artifacts, volatilization 

losses of OC should be significantly less than those resulting from 24-hr average sampling. 

3. What are the PM10-2.5 speciation sampling artifacts that may be encountered using the 

samplers mentioned above and how should they be addressed? Is speciation by the difference 

method problematic for PM10-2.5 speciation and if so what specific issues make it problematic? 

Evaluate OC artifacts by comparing the 24-hr OC filter based measurements with the integrated 

semi-continuous measurements recommended in (2.) above. 

4. The current and most widely used PM2.5 speciation sampler is the MetOne SASS and it has a 

flow rate of 6.7 Liters per minute (Lpm) which is significantly lower than either the FRM for 

PM10-2.5 mass or the dichotomous sampler (16.7 Lpm). If this sampler was configured for PM10-

2.5 by difference, would the 6.7 Lpm flow rate be problematic, especially with the need to 

compare reconstructed mass to the mass collected by the PM10-2.5 FRM? 

The lower flow will likely impact the precision and accuracy of the MetOne SASS as compared 

to PM10-2.5 , but why speculate, perform the field test experiments! 

5. Is the amount of particle mass collected on the dichotomous filters (especially the minor 

flow) sufficient for speciation chemical analysis? 

Survey the concentration ranges from existing CSN measurement networks and calculate the 

expected reductions resulting from flow differences in the dichotomous sampler. If the range in 

chemical speciation concentrations estimated for these adjusted flows remain within the 

detection limits of the analytical methods, case closed. If not, you will need to consider other 

options. 
36 36

PM10-2.5 Species or Components 

1. Table 1 provides a list of proposed PM10-2.5 species and analysis methods. Among these 

species, which are most important? Are there important PM10-2.5 species or components 

missing from this list? Are there important analysis methods missing from this list? 

The compiled list is reasonable for the majority of contributing sources to PM10-2.5. There is 

always the possibility of a unique PM coarse source whose chemical composition is not on this 

list and would require the application of species specific analytical technique. 

2. In the consideration of potential ion measurements for PM10-2.5 species, what ions should be 

on the target list? Are nitrate or ammonium ions important? If so, is an acid gas denuder and 

nylon filter required for the proper collection of these species in PM10-2.5? 

The measurement of nitrate and ammonium ions is important and the measurement technique 

requires the application of appropriate denuders. 

3. The 2004 CD included a list of important PM10-2.5 components which included biological 

materials and fly ashes. If these species are important to characterize, what specific types of 

biological materials and fly ashes should be included? Is scanning electron microscopy (SEM) 

on Teflon filters sufficient to quantify and identify these species? Is the proposed total protein 

assay technique important to obtain a quantitative indicator of the total biological material 

present? 

SEM analyses are very labor intensive and not very quantitative. I would suggest a plot study 

should be carried out to demonstrate its potential utility in this application. 

4. Can the complication of particle size and absorption effects in XRF be resolved using 

absorption correction factors? If not, what other method(s) should be considered? 

Absorption correction factors are likely to be variable and only reproducible in controlled 

environments. Consider the application of ICP/MS analytical technique. 

5. Are metal oxides a significant source of interference in thermal-optical analysis (TOA) of 

PM10-2.5 for OC and EC given the large expected soil component? If so, how should this 

interference be addressed? 

 

This is an interesting research question that requires an investment of resources to study the 

phenomena in the laboratory and the field. 

Network Design

1. Are sites with high PM10 and low PM2.5 good candidate sites for PM10-2.5 speciation? 
37 37

 Given that there will be some urban and rural NCore monitoring sites with PM10-2.5 speciation, 

what other factors should be considered in selecting the pilot monitoring and long-term sites or 

locations? 

The majority (if not all) of urban NCore monitoring sites are not deployed in locations to 

adequately sample PM10-2.5 exposures. The likely source regions impacting PM10-2.5 exposures in 

urban areas are traffic related and associated with populations situate within 500m of major 

highways. 

2. If there is an opportunity to modify the NCore PM10-2.5 speciation monitoring requirements 

during a future rulemaking, should changes to the network design be considered? For example, 

changing the total number of required monitors and/or the required locations? 

The design criteria for locating urban NCore level 2 monitoring sites must consider 

measurements in neighborhoods in proximity (e.g. within 500m) of significant traffic sources 

(major highways). Estimates of population with 500m of major roadways within metropolitan 

areas is one metric for determining the distribution of traffic impacted vs. central urban monitors 

to be deployed. One in three urban monitors deployed to characterize exposures within traffic 

impacted neighborhoods would be a reasonable starting point. 
38 38

Dr. Delbert J. Eatough 

I. General comments: 

 The speciation of coarse particles being undertaken by EPA as part of the revisions to the 

Ambient Air Monitoring Regulations in connection with the EPA final rule to revise the NAAQS 

for PM is a new undertaking for the agency. EPA is to be commended for the commitment to 

speciation of the PM10-2.5 (coarse) particle fraction of PM10, even though a NAAQS for coarse 

particles has not been set by the agency. I encourage the agency to not be limited to the thinking 

of the past 30+ years with respect to monitoring and speciation of fine particles. The speciation 

program for fine particles has been necessarily tied to the PM2.5 sampling FRM because of the 

requirement to understand the speciation of PM2.5 as traditionally sampled by conventional filter 

pack techniques, the basis of the standard. This has lead to a disparity between our 

understanding of sampling of fine particles, the optimization of the understanding of components 

of fine particles which are not well sampled by the FRM and any subsequent improvement in our 

understanding of the etiology of health effects related to fine particles to the extent that the mass 

and composition have been inaccurately measured by these techniques. A coarse particle 

standard does not yet exist. The health effects which may be associated with exposure to coarse 

particles are not currently well understood. Therefore, I recommend that EPA include important 

aspects of improved PM monitoring methods in the coarse particle speciation program to allow 

for a better tie of all components to any observed health effects exacerbated by exposure to 

coarse particles. 

 While many components of coarse particles will be unaffected by the sampling protocols 

used, this is not true for all components. The components listed on slide 9 in the presentation by 

Joann Rice represents the current focus of EPA in this sampling effort. Most of the components 

listed in that slide will not be significantly affect by the sampling methods used. However, this 

is not true for Ammonium and nitrate ions, nor for the semi-volatile fraction of organic C. Both 

are components which need to be well understood. Inattention to sampling artifacts in the 

program will bias the results towards those components which are not affected by the sampling 

method. There are at least two areas where the sampling methods used will significantly affect 

the obtained outcome. 

 In the review of these two areas in the material to follow, I have focused mainly on our 

past work. I have done this because of the short time available to provide comments and because 

this work is pertinent to the charge questions asked by EPA. However, it should be recognized 

that the effects noted below have been observed by several investigators. 
39 39

II. Alteration of the Mass and Chemical Composition of Coarse Particles During 

Sampling by Mixing Both Fine and Coarse Particles Together.

 The origins of fine and coarse particles in the atmosphere are very different, and as a 

result their compositions are very different (U.S. EPA 2004). Fine particles are dominated by 

primary and secondary material associated with anthropogenic emissions. Ammonium sulfate, 

ammonium nitrate, organic material and elemental carbon are major components of these fine 

particles. If the aerosol is acidic, the concentrations of ammonium nitrate are low. In contrast, 

coarse particles are dominated by crustal material, some biogenic material and materials formed 

from abrasive action, e.g. tire debris, etc. Sulfate concentrations are generally very low. Nitrate 

can be present in these fine particles, but is generally there are a result of the conversion of sea 

salt to sodium nitrate by the reaction with nitric acid (e.g., Ellis et al., 1983). 

 NaCl(s) + HNO3(g) → NaNO3(s) + HCl(g) 

When fine and coarse particles are collected together reactions can occur in the collected mixture 

because of the introduction of dissimilar compositions. The best documented of these changes is 

the loss of coarse particulate nitrate by reaction with acidic salts in the fine particles when the 

two size fractions are mixed on the filter (e.g., Eatough and Ellis, 1983), 

 NaNO3(s) + HN4HSO4(s) → NaHN4SO4(s) + HNO3(g) 

and similar reactions. In addition, changes in coarse particulate organic material can be expected 

to occur from reaction with fine particulate reactive species. The presence of these artifacts, 

some of which are certainly presently unknown, suggests that coarse particulate mass and 

composition is best determined if the fine and coarse particles are collected and analyzed 

separately. This argues for the use of a dicot sampler or similar device. The EPA heard several 

strong pleas fore use of dichot samplers and the avoidance of FM integrated PM10 filter collected 

sample (for use in a differential speciation calculation) in the coarse particle speciation network. 

I add my strong vote to those views for the additional reasons listed here and in Section III. 

III. Alteration of the Mass and Chemical Composition of Coarse Particles During 

Sampling by the Loss of Semi-volatile Material During Sampling. 

 Exposure to fine particulate matter (PM2.5, particles with an aerodynamic diameter less 

than 2.5 μm) has been implicated as a contributor to adverse human health effects including 

increases in cardiovascular and pulmonary disease which leads to elevated human mortality and 

morbidity (Pope and Dockery, 2007). The role coarse particulate matter (PM10-2.5) may play in 

exacerbating health problems is not as well understood. PM2.5 in the atmosphere is not 

composed of a single pollutant but consists of both stable and semi-volatile species. Stable 

species in the atmosphere include trace metals (including toxic, crustal, and transition metals), 

black carbon (BC), and sulfate. Semi-volatile material (SVM) exists in dynamic equilibrium 

between the gas and particle phase and includes ammonium nitrate (Finlayson-Pitts and Pitts, 

2004) and low molecular weight organic species (e.g., SVM that exists in the atmosphere in the 
40 40

particle phase can be lost from particles during sampling making it difficult to measure, Eatough 

et al., 2003). The composition of coarse particles may also include these semi-volatile 

components, however this semi-volatile material is less well understood in coarse particles. 

 Several integrated samplers have been developed which accurately determine both 

nonvolatile material (NVM) and SVM concentrations (Eatough et al., 2003). These techniques 

could be applied to the chemical characterization of coarse particles. Although these samplers 

can accurately speciate PM2.5, including SVM, there are several drawbacks to their use. 

Integrated samplers are very labor and cost intensive. Collection of filter media and in-lab 

analysis are time consuming and cost intensive, resulting in data interpretation weeks and months 

from the time of collection. The potential for sample contamination is increased with collection, 

transport, and laboratory analysis. Furthermore, 1-h time resolved data is usually not possible 

with integrated samplers which inhibit the ability to temporally resolve short term changes in 

pollution levels that often occur in urban environments. 

 To overcome these problems, the development of real-time or near real-time instruments 

has been attempted. One of the widely used semi-continuous PM2.5 measurement techniques is 

the Tapered-Element Oscillating Microbalance (TEOM, Patashnick et al., 1991) developed by 

Rupprecht & Patashnick Co., Inc. The TEOM does not accurately determine total PM2.5 mass 

because the particle collection filter is heated to 30-50°C to remove particle bound water, which 

also results in loss of SVM. The Rupprecht & Patashnick Filter Dynamic Measuring System 

(FDMS, Meyer et al., 2002), and GRIMM monitors (Grimm and Eatough, 2009) have been 

developed to measure total PM2.5 mass, including SVM. The GRIMM monitor will measure 

both PM2.5 and PM10-2.5. A dicot based FDMS has now been released by Thermo, and is in use at 

some state monitoring sites, which will also measure both PM2.5 and PM10-2.5. Real-time 

instruments have several advantages including, reliability, cost effectiveness, ease of sampling 

and reduction in labor requirements. One prominent advantage of real-time instruments is the 

ability to temporally resolve short term episodes of PM2.5 that occur in urban environments that 

may be relevant to human health effects. One-hour averaged semi-continuous data has also been 

shown to increase the performance (i.e., reduce uncertainty) of source apportionment techniques 

to determine sources, both primary and secondary, of urban PM (Grover and Eatough, 2008; 

Eatough et al., 2008a). 

 Both the FDMS TEOM and GRIMM Technologies Inc. (Model 1.180) optical particle 

monitor have Nafion dryers at the inlet to remove particulate water. PM2.5 measurements with 

these two instruments were compared during the winter of 2007 in Lindon, Utah. The excellent 

agreement between these two instruments (Figure 1, from Hansen et al., 2009) suggest that both 

measure particulate SVM in a similar manner. 
41

0

20

40

60

80

100

120

G

R

MI M, μg/m3

41 

0 20 40 60 80 100 120

FDMS TEOM, μg/m3

y = (0.995±0.007)x + 3.0±5.0 μg/m3

N = 567, R2 = 0.97

Sigma = 4.0 μg/m3 (±9.6%) Figure 1. Comparison of 

PM2.5 hourly average mass 

measurements by an FDMSTEOM and a GRIMM 

monitor for the 19 January 

through 16 February 2007 

study at Lindon, Utah. The 

linear regression fit to the 

results are given in the Figure 

 Mass balance studies between 1-h measurements of PM2.5 mass with an R&P FDMS 

TEOM and 1-h measurement of fine particulate components, including the semi-volatile nitrate 

and organic material in Riverside, California have also shown excellent agreement (Figure 2, 

from Grover et al., 2008b), indicating the semi-volatile material is well measured by the FDMS 

TEOM. In This study, the SVM averaged 36% of the total PM2.5 mass. 

22 23 24 25 26 27 28 29 30 31 1 2 3 4 5 6 7 8 9 10 11 12 13 14

Date (July - August 2005)

0

20

40

60

80

μg/m3

FDMS SUM

0 20 40 60 8

FDMS (μg/m3)

Figure 2. Semi-continuous 

constructed mass (y axis in 

both plots) vs. FDMS 

measured mass. Constructed 

mass is the sum of all the 

major components of the 

aerosol including; NVOM, 

SVOM, EC, NH4NO3 and 

ammonium sulfate. 

0

0

20

40

60

80

C

onstructed Mass (μg/m3)

 
The above referenced studies indicate that PM2.5 mass and components, including the semivolatile material can be reliably determined with technology currently available commercially. 

The ability of the GRIMM monitor to measure the coarse particle fraction and the recent 

introduction of the dicot FDMS TEOM should allow similar comparisons to be made for PM10-

2.5. 

 A measure of the amount of semi-volatile material in both fine and coarse particles can 

also be using the conventional TEOM (30 or 50 ΕC), coupled with FDMS TEOM and GRIMM 

monitor data. This is illustrated by results obtained during the study in Lindon (Hansen et al., 

2009). Concentrations of PM2.5 mass were made with a conventional TEOM, and FDMS TEOM 

and the GRIMM monitor. PM10 was measured with a conventional TEOM and the GRIMM 

monitor. The conventional TEOM does not measure the semi-volatile material. The differences 

between the conventional TEOM and either the FDMS TEOM or GRIMM monitor give the total 

semi-volatile material in the particles (Grover et al., 2008b). The calculated PM2.5 and PM10

SVM concentrations obtained from the FDMS TEOM, GRIMM and conventional TEOM 

monitor data are compared in Figure 3 (from Hansen et al., 2009). Included in Figure 3 are error 

bars indicated the estimated uncertainty in the comparison. As indicated, the data tend to scatter 

around the slope equals one line, however, some of the points show a bias towards higher SVM 

concentrations for the PM10. This indicates the presence of semi-volatile material in the coarse 

fraction, small, but statistically significant. The SVM material will be composed of semi-volatile 

ammonium nitrate and organic material. These secondary components would be expected to be 

concentrated in the fine particles. Thus the results shown in Figure 3 are consistent with these 

expectations based on atmospheric formation processes. However, a small, but significant 

amount of semi-volatile material is present in the coarse particles. Chemical analysis of 24-h 

integrated filter samples confirmed that little nitrate was present in the coarse particles, 

suggesting the coarse particulate semi-volatile material is organic. 

42 

60

0 10 20 30 40 50 60

SVM, PM2.5, μg/m3

 

0

10

20

30

40

50

S

V

M, P

M10, μ

g/m3

Figure 3. Comparison of the 

calculated concentrations of 

PM2.5 and PM10 semi-volatile 

material at Lindon UT, see 

text. 

 

 
 

Comparisons such as those shown here should be obtained in the EPA coarse speciation 

monitoring program to determine if semi-volatile material is important in coarse particles in a 

variety of urban areas. This will in turn, indicate if conventional filter pack sampling can be 

expected to give an accurate picture of total coarse particle mass and composition. If significant 

semi-volatile material is identified in an Urban environment then semi-continuous monitors 

which will measure the expected semi-volatile components (e.g. ion chromatographic monitors 

such as the URG AIM and carbon analyzers such as the Sunset Dual Oven monitor which 

determine both nonvolatile and semi-volatile carbonaceous material) can help elucidate the 

sources of the semi-volatile material. This will help to close a hole in the chemical speciation of 

coarse particles from the start which has never been adequately addressed in fine particle 

research in past EPA monitoring programs. 

PM10-2.5 Speciation Measurement

1. Table 1provides a list of proposed PM10-2.5 species and analysis methods. Are there 

additional PM10-2.5 target species or methods that can be used to help identify the source of 

unidentified mass in order to obtain better mass closure? 

Because of the probable alteration of PM10-2.5 composition and mass when fine and coarse 

particles are mixed during sampling (see above discussion), all analyses should be done on a 

PM10-2.5 discrete sample and not inferred by a PM10 - PM2.5 difference measurement, i.e. a dicot 

(or equivalent) sampler should be used. 

A significant problem with the protocols given in Table 1 is that they provide for the 

determination of species retained on a filter in an integrated sample only. As I have outlined 

above, EPA should take advantage of the requirement to characterize coarse particles for better 

health effect assessment by insuring that semi-volatile particulate matter which is not retained in 

the particles is quantified. This could first involve the semi-continuous determination of total 

semi-volatile material by comparison of PM10-2.5 mass using a conventional TEOM to measure 

nonvolatile and either a FDMS TEOM or a GRIMM monitor to measure total mass. The 

difference between the two is a measure of semi-volatile mass. These measurements should all 

be made on a PM10-2.5 basis and not inferred from difference measurements. The 24-h average of 

the 1-h conventional TEOM data would be compared to the 24-h integrated filter measured mass. 

If these comparison indicates significant semi-volatile material is present in an air shed, then the 

composition of the semi-volatile material could be determined using monitors such as the URG 

AIM (for nitrate) of the Sunset Dual Oven monitor (for semi-volatile organic material). For the 

reasons outlined above, it is important that all these measurements be done on a PM10-2.5 

collected sample and not determined by difference. 

Fly Ash. We have done extensive work on the analysis of fly ash in collect PM (e.g. Eatough et 

al., 2000). SEM analysis is only practicable on Polycarbonate filters. If the data are intended to 

be use in source apportionment, a PM10 sample should be analyzed. We found it best to pre-treat 

the sample with an acid wash and firing before analysis to optimize detection of insoluble fly ash 

particles. 
2. Various sampling devices, including dichotomous samplers, MetOne SASS speciation 

monitors, PM10 and PM2.5 FRMs are potential sampling devices (with the appropriate filter 

types) for PM10-2.5 speciation. Among these sampler types, which should be included or excluded 

from the pilot network design? Are there other sampling devices not listed here that should be 

considered? 

For reason outlined in #1 and discussed in more detail above, chemical speciation should only be 

done on a dichotomous sampler (or equivalent device to provide a discrete PM10-2.5 sample). 

This would rule out the use of PM10 FRM samplers. 

3. What are the PM10-2.5 speciation sampling artifacts that may be encountered using the 

samplers mentioned above and how should they be addressed? Is speciation by the difference 

method problematic for PM10-2.5 speciation and if so what specific issues make it problematic?

Speciation by the difference method is problematical. Details on artifacts and the approach 

which should be taken in speciation are discussed in detail above. 

4. The current and most widely used PM2.5 speciation sampler is the MetOne SASS and it has a 

flow rate of 6.7 Liters per minute (Lpm) which is significantly lower than either the FRM for 

PM10-2.5 mass or the dichotomous sampler (16.7 Lpm). If this sampler was configured for PM10-

2.5 by difference, would the 6.7 Lpm flow rate be problematic, especially with the need to 

compare reconstructed mass to the mass collected by the PM10-2.5 FRM? 

It has been my experience, based on extensive work with diffusion denuder samplers, that in a 

24-h sample the results obtained are largely independent of flow rate. This is because the 

kinetics for changes which occur during sampling are generally of the order of 10s of minutes or 

shorter. However, a difference method suffers the problems discussed above at any flow rate. 

5. The current and most widely used PM2.5 speciation sampler is the MetOne SASS and it has a 

flow rate of 6.7 Liters per minute (Lpm) which is significantly lower than either the FRM for 

PM10-2.5 mass or the dichotomous sampler (16.7 Lpm). If this sampler was configured for PM10-

2.5 by difference, would the 6.7 Lpm flow rate be problematic, especially with the need to 

compare reconstructed mass to the mass collected by the PM10-2.5 FRM? 

Since the total mass collected in the minor flow is a function of the inlet flow and not the minor 

flow, I would not think this would be a problem. 

PM10-2.5 Species or Components

1. Table 1 provides a list of proposed PM10-2.5 species and analysis methods. Among these 

species, which are most important? Are there important PM10-2.5 species or components missing 

from this list? Are there important analysis methods missing from this list?

If your goal is characterization for source apportionment and health effect etiology applications, 

none of the components should be eliminated. The importance of quantifying semi-volatile 

material in coarse particles has been discussed in the previous section and in the introductory 

material. 

 44
2. In the consideration of potential ion measurements for PM10-2.5 species, what ions should be 

on the target list? Are nitrate or ammonium ions important? If so, is an acid gas denuder and 

nylon filter required for the proper collection of these species in PM10-2.5?

Nitrate is expected to be present mainly as the sodium salt. But knowing both nitrate and 

ammonium ion would be valuable. If, as we suspect, ammonium nitrate is negligible in most 

Urban areas in coarse particles, it would not seem worth the effort to use a denuder in integrated 

sampling, if you also include monitoring for semi-volatile material with conventional TEOM and 

either FDMS TEOM or GRIMM monitors as outlined above. This would highlight the possible 

presence of ammonium nitrate and followup with an AIMS would verify the ammonium nitrate 

presence. If however, you do not monitor for semi-volatile species, then using a denuder system 

for the coarse particle collection is advised. Do you have any data on the transfer of coarse 

particles through an annular denuder? 

3. The 2004 CD included a list of important PM10-2.5 components which included biological 

materials and fly ashes. If these species are important to characterize, what specific types of 

biological materials and fly ashes should be included? Is scanning electron microscopy (SEM) 

on Teflon filters sufficient to quantify and identify these species? Is the proposed total protein 

assay technique important to obtain a quantitative indicator of the total biological material 

present? 

I have commented on fly ash above. I am not familiar with monitoring for biological materials. 

4. Can the complication of particle size and absorption effects in XRF be resolved using 

absorption correction factors? If not, what other method(s) should be considered?

I will leave this to those who know. 

5. Are metal oxides a significant source of interference in thermal-optical analysis (TOA) of 

PM10-2.5 for OC and EC given the large expected soil component? If so, how should this 

interference be addressed?

This is certainly a potential interference but I do not know to what extent. Those knowledge in 

this area did not seem to think this would be a large problem. 

Network Design

1. Are sites with high PM10 and low PM2.5 good candidate sites for PM10-2.5 speciation? Given 

that there will be some urban and rural NCore monitoring sites with PM10-2.5 speciation, what 

other factors should be considered in selecting the pilot monitoring and long-term sites or 

locations?

This question seems to imply the use of difference methods. I have outlined why this is not a 

good idea above. 

 45
2. If there is an opportunity to modify the NCore PM10-2.5 speciation monitoring requirements 

during a future rulemaking, should changes to the network design be considered? For example, 

changing the total number of required monitors and/or the required locations?

I think the routine inclusion of monitoring for semi-volatile species using the sem-continuous 

mass monitors I have mentioned above would be a valuable addition. This would proved input 

on both PM10-2.5 mass and components as well as give diurnal data which would be very helpful 

in understanding the effects of changing meteorology, emissions and atmospheric chemistry on 

the observed concentrations and composition. 

References

Eatough, D.J.; Grover, B.D.; Woolwine, W.R.; Eatough, N.L.;Long, R.; Farber, R. (2008) 

Source Apportionment of 1-hr Semi-Continuous Data During the 2005 Study of Organic 

Aerosols in Riverside (SOAR) Using Positive Matrix Factorization, Atmos. Environ. 42, 

2706-2719. 

Eatough, D.J.; Long, R.W.; Modey, W.K. and Eatough, N.L. Semi-Volatile Secondary Organic 

Aerosol in Urban Atmospheres: Meeting a Measurement Challenge (2003) Atmos. 

Environ. 37, 1277-1292. 

Eatough D.J.; Farber R.J. and Watson J.G. (2000) Second Generation Chemical Mass Balance 

Source Apportionment of Sulfur Oxides and sulfate at the Grand Canyon during the 

Project MOHAVE Summer Intensive, J. Air & Waste Management Association 50, 759-

774. 

Eatough D.J. and Ellis E.C. (1983) A Comparison of High and Low Volume Particulate Matter 

Nitrate Concentrations in the Los Angeles Basin, Aerosol Science and Technology, 2, 

177. 

Ellis E.C.; Farber R.J. and Eatough D.J. (1983) Formation of Coarse Particle Secondary Nitrate 

in the Los Angeles Basin, Aerosol Science and Technology, 2, 176. 

Finalyson-Pitts B.J.; Pitts, J.N. Chemistry Of The Upper And Lower Atmosphere: Theory, 

Experiments and Applications; Elsevier, 2004. 

Grimm, H. and Eatough, D.J. (2009) Aerosol Measurement: The Use of Optical Light Scattering 

for the Determination of Particulate Size Distribution, and Particulate Mass, Including 

the Semi-Volatile Fraction; J. Air Waste Manage. Assoc. 59, 101-107. 

Grover, B.D. and Eatough, D.J. (2008a) Source Apportionment of One-Hour Semi-Continuous 

Data using Positive Matrix Factorization with Total Mass (Nonvolatile plus SemiVolatile) Measured by the R&P FDMS Monitor; Aerosol Sci. Technol. 42, 28-39. 

Grover, B.D.; Eatough N.L.; Woolwine, W.R.; Cannon, J.P.; Eatough, D.J.; Long, R.W. (2008b) 

Semi-continuous Mass Closure of the Major Components of Fine Particulate Matter in 

 46
Riverside, CA; Atmos. Environ. 42, 250-260. 

Hansen, J.; Woolwine, W.R. III; Bates, B.L, Clark, J.M.; Kuprov, R.Y.; Mukherjee, P.; Murray, 

J.A.; Simmons, M.A.; Waite, M.F.; Eatough, N.L.; Eatough, D.J.; Long R. and Grover 

B.D. (2009) Semi-Continuous PM2.5 and PM10 Mass and Composition Measurements in 

Lindon, Utah During Winter, 2007. J. Air Waste Manage. Assoc., in press. 

Meyer, M.B.; Patashnick, H.; Ambs, J.L. (2002) Ongoing Development of a Continuous 

Reference Standard Particulate Matter Mass Monitor for Ambient Air; paper presented at 

the Symposium on Air Quality Measurement Methods and Technology, San Francisco, 

CA, November. 

Patashnick, H.; Rupprecht, E.G. Continuous PM10 Measurements Using the Tapered Element 

Oscillating Microbalance; J. of Air & Waste Manage. Assoc. 41, 1079-1083. 

Pope, C.A. III; Dockery, D.W. Health Effects of Fine Particulate Air Pollution: Lines that 

Connect; J. Air & Waste Manage. Assoc. 2007, 57, 709-742. 

U.S. EPA (2004) Air Quality Criteria for Particulate Matter. Report No. EPA/600/P-99/002aF, 

Environmental Protection Agency, Research Triangle Park, NC. 

 47
Mr. Dirk Felton 

PM10-2.5 Speciation Measurement

1. Table 1 provides a list of proposed PM10-2.5 species and analysis methods. Are there 

additional PM10-2.5 target species or methods that can be used to help identify the source of 

unidentified mass in order to obtain better mass closure? 

The conversion to OM from OC is contributing to the unidentified mass issue. The EPA should 

endeavor to reduce this uncertainty by performing detailed OC component and molecular marker 

analysis on some of the filter samples. 

2. Various sampling devices, including dichotomous samplers, MetOne SASS speciation 

monitors, PM10 and PM2.5 FRMs are potential sampling devices (with the appropriate filter 

types) for PM10-2.5 speciation. Among these sampler types, which should be included or excluded 

from the pilot network design? Are there other sampling devices not listed here that should be 

considered? 

The SASS PM-10 inlet is not yet viable and the SASS may not have enough sample volume for 

some PMc components in some areas of the country. There are many existing Cascade Impactor 

designs and it is possible that one of those could be modified to make it appropriate for 

collection of some of the components of interest for the PMc pilot. Other technologies also not 

on this list include continuous instruments and particle mass spectrometry. Again these latter 

two new technologies would have to be modified with suitable inlets and they are not user 

friendly but they have the potential of producing the best results. 

3. What are the PM10-2.5 speciation sampling artifacts that may be encountered using the 

samplers mentioned above and how should they be addressed? Is speciation by the difference 

method problematic for PM10-2.5 speciation and if so what specific issues make it problematic? 

The difference method is likely to suffer the most in areas with high nitrate and high OC. The 

problem is that component conversion and volatilization are likely to occur preferentially for one 

component size fraction (PM-10, PM-2.5) or the other depending on the source. This will make 

the bias between the size fractions component specific. 

The Dicot method also has the disadvantage of requiring an adjustment for fine particle 

intrusion. This adjustment to Dicot mass concentration is less attractive for component analysis 

because it is not known if the correction or the presence of fine particles on the coarse mode 

filter will preferentially affect one component over another. 

4. The current and most widely used PM2.5 speciation sampler is the MetOne SASS and it has a 

flow rate of 6.7 Liters per minute (Lpm) which is significantly lower than either the FRM for 

PM10-2.5 mass or the dichotomous sampler (16.7 Lpm). If this sampler was configured for PM10-

2.5 by difference, would the 6.7 Lpm flow rate be problematic, especially with the need to 

compare reconstructed mass to the mass collected by the PM10-2.5 FRM? 

 48
In Queens, NY, typical 16.7 L/min FRM filter loadings are 260 ug for PM-2.5 and 480 ug for 

PM-10. It is expected that a 6.7 L/min sampler would have loadings of 104 ug and 192 ug 

respectively. These lower loadings certainly increase the significance of the precision of the 

weighing procedure and the magnitude of the filter blanks which are permitted to be as high as 

30 ug. 

During the recent FEM equivalency evaluations performed by ThermoFisher Scientific, Franklin, 

MA, the vendor was required to run filter based low volume FRM PM-2.5 and PM-10 samplers 

in triplicate. The average standard deviation of the three calculated PMc values over 44 

sampling days was 0.8 ug/m3. If we assume that the 6.7 L/min sampler performs as well as a 

carefully operated FRM during an equivalency test, which should be considered a best case, 0.8 

ug would indicate a standard deviation of about 20 ug of filter loading on the 6.7 L/min sampler. 

That makes the precision of the method an issue since the expected PMc by difference is only 88 

ug for the 6.7 L/min sampler. 

5. Is the amount of particle mass collected on the dichotomous filters (especially the minor 

flow) sufficient for speciation chemical analysis? 

During the Thermo Fischer Scientific FEM evaluation in Queens NY last summer, the 

correlation between the virtual impactor Coarse mode data and PMc by filter difference was not 

as good as the correlation with the fine mode. This is not too surprising considering the low 

PMc concentrations and the issue of large particle retention on filters prior to gravimetric 

analysis. The amount of mass should be sufficient for most analysis but the precision of the PMc 

mass measurements by Dicot will not be as good as that for PMc by difference. 

PM10-2.5 Species or Components 

1. Table 1 provides a list of proposed PM10-2.5 species and analysis methods. Among these 

species, which are most important? Are there important PM10-2.5 species or components missing 

from this list? Are there important analysis methods missing from this list? 

The first question will have a different answer depending on the end use of the data. The PMc 

component mix will vary greatly by location, season and proximity to sources. In the northeast, 

the concentrations of elements in PMc tend to be around 30% of the PMc mass. Again from a 

northeast perspective, the only element missing from Table 1 is Vanadium which can have 

significant PMc concentrations in some areas. The New York State Department of 

Environmental Conservation (NYSDEC) undertook a pilot study for PMc speciation by 

difference. Low volume PM-2.5 and PM-10 FRM samplers were installed in New York City 

and in Niagara Falls. The samplers were operated on a 1/6 day schedule for a year and the filters 

were weighed and analyzed by XRF. The results demonstrated that some species such as Pb 

were found nearly equally in the fine and coarse mode. Arsenic was unique in that it appears to 

have a distinct source in both fine and coarse modes. 

 49
The concentrations of the elemental data for all but about 10 elements were very low in the 

coarse mode. 

PMcoarse to PM-10 Ratio: Canal St 2005 (Mass and Elements)

0

0.2

0.4

0.6

0.8

1

Se S Ni Zn Br As PM Pb K Mn Na Cu V Sr Zr Fe Al Ti Ca Si Cl Cr Mg

Median 25th %tile 75th %tile

NYC PMcoarse and PM-2.5 Ave Elemental Concentrations 

Calendar Year 2005 (Sulfur omitted)

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

Fe Si Ca Na Cl Al K Mg Zn V Ti Cu P Mn Pb Ni Br La Sm Zr Sr Ce

ug/m3

PMc Annual Ave Conc PM-2.5 Annual Ave Conc PMc 25%tile

PMc 75%tile PM-2.5 25%tile PM-2.5 75%tile

Carbon is probably the most important overall group of PM components. It includes many 

compounds that are not uniquely identified and are likely to be correlated with health effects. 

The poor understanding of OC’s conversion to organic mass is also not well understood which 

makes it difficult to accurately characterize OC PMc. Continuous carbon monitoring is the most 

cost effective means of obtaining daily datasets. The Sunset Labs instrument is available as a 

prototype in a configuration for PM-10. The pilot should establish a few sites in different parts 

of the country with hourly OC/ECcoarse by difference. The EPA should also attempt to include 

the volatile portion of all of the components collected in the pilot. 

 50
2. In the consideration of potential ion measurements for PM10-2.5 species, what ions should be 

on the target list? Are nitrate or ammonium ions important? If so, is an acid gas denuder and 

nylon filter required for the proper collection of these species in PM10-2.5? 

Soluble ions are less important for eastern sites. The ion concentrations from Table 1, except for 

Nitrate, can be estimated from the elemental data. This will not be the case for the west where 

ammonium nitrate is very important and cannot be estimated from other measurements. A 

denuder should be employed and the sampler should be modified to keep the sample cool after 

and during the sampling event if possible. 

3. The 2004 CD included a list of important PM10-2.5 components which included biological 

materials and fly ashes. If these species are important to characterize, what specific types of 

biological materials and fly ashes should be included? Is scanning electron microscopy (SEM) 

on Teflon filters sufficient to quantify and identify these species? Is the proposed total protein 

assay technique important to obtain a quantitative indicator of the total biological material 

present? 

As with all PMc data, the relative importance of one component over another is dependent on 

location and sources. In and around industrial areas and large, older urban areas such as cities in 

the midwest and northeast, fly ash and oil soot are found in significant concentrations in the air. 

Often the majority of these particles are larger than 10 microns and are likely to be excluded in 

PMc measurements. Since these particles may be correlated with health effects, the pilot 

monitoring program should consider evaluating concentration differences in results between 

samples collected with PMc samplers and samplers with low volume TSP inlets such as the 

URG-2000-30DG. 

Teflon filters are suitable for SEM work but are not ideal. Their depth structure prevents reliable 

quantitation because it tends to hide the smaller particles. 

Biological materials such as mold spores, insect parts and moth scales will partially be collected 

with PMc samplers. It certainly is plausible that mold spores could have a correlation with 

health effects but it is unlikely that generalized assay tests would sufficiently identify specific 

components of PM that probably affect only a limited portion of the population. 

Pollen for the most part is too large to be included in PMc measurements. Specialized samplers 

such as the Burkhard spore trap and Rotorod sampler are used for Pollen sampling and counting. 

4. Can the complication of particle size and absorption effects in XRF be resolved using 

absorption correction factors? If not, what other method(s) should be considered? 

The XRF analysis for the more heavily loaded PM-10 filters is modified by extending the count 

time for the detector. Extending the count time may or may not eliminate the uncertainty 

associated with an increase in X-Ray absorption. The EPA should sponsor experimentation by 

loading filters with different component mixes of PMc and then compare the XRF results with 

ICPMS digestive analysis. 

 51
5. Are metal oxides a significant source of interference in thermal-optical analysis (TOA) of 

PM10-2.5 for OC and EC given the large expected soil component? If so, how should this 

interference be addressed? 

 

The IMPROVE program should have some insight into this. 

Network Design

1. Are sites with high PM10 and low PM2.5 good candidate sites for PM10-2.5 speciation? Given 

that there will be some urban and rural NCore monitoring sites with PM10-2.5 speciation, what 

other factors should be considered in selecting the pilot monitoring and long-term sites or 

locations? 

The best site is the one that has significant concentrations of the PMc component that has the 

greatest correlation with health effects. To that end, the pilot should be designed to provide 

survey information covering the entire range of component mix and concentration ranges. This 

is the most effective way to determine the importance of specific components of PMc for the 

design of a future more relevant PMc network. NCore sites are situated to represent large spatial 

scales and generally will tend to have relatively low contributions from known sources of larger 

particles. 

There are no standards for components of PMc or for mass of PMc so the pilot as well as the 

initial longer term deployment should be designed to help ascertain the highest concentrations of 

PMc components likely to be associated with health effects. This strategy will accelerate the 

linking of health effects and individual PMc component concentrations 

2. If there is an opportunity to modify the NCore PM10-2.5 speciation monitoring requirements 

during a future rulemaking, should changes to the network design be considered? For example, 

changing the total number of required monitors and/or the required locations? 

It is appropriate to tailor the PMc speciation program to the species that are prevalent and likely 

to be related to health effects in specific regions of the country. In northeastern cities for 

instance, PMc OC/EC are likely to be much more important than PMc elements. In western 

cities, soil and nitrate are likely to more relevant. Once health effect correlations are found in 

areas with high concentrations of specific components of PMc, the network can be modified to 

include that component in sampling efforts in the rest of the network. 

Health researchers are continually stressing a preference for daily data due to lag structure in 

health effects studies and the PMc pilot should be designed to the extent possible to provide daily 

or continuous data. 

 52
Dr. Philip Hopke 

PM10-2.5 Speciation Measurement

1. Table 1 provides a list of proposed PM10-2.5 species and analysis methods. Are there 

additional PM10-2.5 target species or methods that can be used to help identify the source of 

unidentified mass in order to obtain better mass closure? 

Part of the issue here is what sampling method is to be used. Is there really sufficient precision to 

be able to use the difference method which unfortunately is still being put forth as the standard 

approach? I suggest that the key is less on the analytical method as on the sampling approach. 

2. Various sampling devices, including dichotomous samplers, MetOne SASS speciation 

monitors, PM10 and PM2.5 FRMs are potential sampling devices (with the appropriate filter 

types) for PM10-2.5 speciation. Among these sampler types, which should be included or excluded 

from the pilot network design? Are there other sampling devices not listed here that should be 

considered? 

I strongly recommend against using the difference method. There is the potential for substantial 

interactions between the fine and coarse particles on the PM10 filter. For example, fine NH4NO3 

can dissociate to produce HNO3 that would react with alkaline coarse particles. This could 

produce an overestimate of coarse NO3. 

Dichotomous samplers complicate the analyses by putting about 10% of the fine particle mass 

onto the coarse particle filter. 

It probably makes more sense to develop an impactor system to collect specific coarse particle 

samples where there would be little supercoarse or fine particle contamination. Such an 

impactor would have two stages. The first would have as sharp as possible PM10 cut and the 

second would have a sharp PM2.5 cut. The PM2.5 stage would be the one to be analyzed. 

However, since this approach was not adopted when the idea of coarse particles was first 

considered (such that it would now be available), it makes sense to go with the dichot. 

3. What are the PM10-2.5 speciation sampling artifacts that may be encountered using the 

samplers mentioned above and how should they be addressed? Is speciation by the difference 

method problematic for PM10-2.5 speciation and if so what specific issues make it problematic? 

See above. 

One question is whether low volume systems provide sufficiently large samples for all of the 

analyses envisioned. Clarkson is involved in an EPA CRADA to test a high volume (400 LPM) 

dichotomous sampler that would provide greater mass for chemical characterization. However, 

it is still a virtual impaction system that would still intermix some fine particles into the coarse 

particle sample. 

 53
4. The current and most widely used PM2.5 speciation sampler is the MetOne SASS and it has a 

flow rate of 6.7 Liters per minute (Lpm) which is significantly lower than either the FRM for 

PM10-2.5 mass or the dichotomous sampler (16.7 Lpm). If this sampler was configured for PM10-

2.5 by difference, would the 6.7 Lpm flow rate be problematic, especially with the need to 

compare reconstructed mass to the mass collected by the PM10-2.5 FRM? 

This is why they should develop a reasonable flow, simple impactor system to collect PM10-2.5. 

It should be relatively easy to design and build such a system. It should have been done rather 

than spending all of the money that has been spent on trying to justify the inherently flawed 

difference method and the problematic dichotomous sampler. 

5. Is the amount of particle mass collected on the dichotomous filters (especially the minor 

flow) sufficient for speciation chemical analysis? 

Probably not. However, it is possible to build high flow dichots that would provide sufficiently 

large samples to ensure good analytical precision. I have provided a presentation outlining such 

a system that is ready for testing. 

PM10-2.5 Species or Components 

1. Table 1 provides a list of proposed PM10-2.5 species and analysis methods. Among these 

species, which are most important? Are there important PM10-2.5 species or components missing 

from this list? Are there important analysis methods missing from this list? 

We know a lot less about the coarse fraction and what are critical species particularly for primary 

biological species that are going to be more prevalent in coarse fraction samples compared to 

fine particle samples. Protein alone is highly unlikely to provide a reliable estimate of total 

biological particulate mass. 

Are there sufficient resources available to perform CCSEM on enough filters for enough 

particles to provide statistically valid numbers of particles to adequate quantify the particle types. 

Are they envisioning automated analysis of the data? Will they collect secondary electron 

images as well as backscatter images and x-ray spectra? One can envision automated image 

analysis software that could sort the particles into various major categories, but there is no 

discussion of how the analyses are to be conducted. Manual SEM and review of images will not 

be sufficient to provide support to a national network of samplers. 

2. In the consideration of potential ion measurements for PM10-2.5 species, what ions should be 

on the target list? Are nitrate or ammonium ions important? If so, is an acid gas denuder and 

nylon filter required for the proper collection of these species in PM10-2.5? 

Nitrate is important for the coarse sample as well as fine although the coarse particle nitrate is 

generally present because of the reaction of gaseous HNO3 with the alkaline coarse particles. 

This problem also supports the need for using devices that separate coarse and fine fractions and 

not using the difference method. 

 54
3. The 2004 CD included a list of important PM10-2.5 components which included biological 

materials and fly ashes. If these species are important to characterize, what specific types of 

biological materials and fly ashes should be included? Is scanning electron microscopy (SEM) 

on Teflon filters sufficient to quantify and identify these species? Is the proposed total protein 

assay technique important to obtain a quantitative indicator of the total biological material 

present? 

See answer to 1 above. Normally Teflon is not an ideal surface for CCSEM. It can be adequate 

for manual SEM analysis, but it is not possible to have enough people on enough microscopes to 

do enough particles on enough filters to be meaningful. Much of the biological species would be 

more carbohydrates than protein so it is not clear that a total protein assay would suffice to 

provide an index of total biological material. It may be more useful to look at specific species 

such as endotoxin or specific aeroallergens. There are now easy to use kits at reasonable prices 

to perform ELIZA analyses. It is likely that additional species tests could be developed for other 

identified allergens. 

4. Can the complication of particle size and absorption effects in XRF be resolved using 

absorption correction factors? If not, what other method(s) should be considered? 

Again, this depends critically on what is collected. If you are still using the difference method, 

then it makes the XRF analysis much more difficult than if there is a narrower range of particle 

sizes in just a coarse particle sample. Also the differences in composition from location to 

location also need to be considered as it is the combination of particle composition and size that 

affect the penetrability of the fluoresced x-ray. 

5. Are metal oxides a significant source of interference in thermal-optical analysis (TOA) of 

PM10-2.5 for OC and EC given the large expected soil component? If so, how should this 

interference be addressed? 

I am not sure that we really know enough to be able to develop quantitative relationships 

between transition metal oxides and changes in relative OC/EC values. There is evidence for 

influence but not clear relationships and it certainly will also depend on the nature of the 

carbonaceous material as well as the nature of the oxides. 

Network Design

1. Are sites with high PM10 and low PM2.5 good candidate sites for PM10-2.5 speciation? Given 

that there will be some urban and rural NCore monitoring sites with PM10-2.5 speciation, what 

other factors should be considered in selecting the pilot monitoring and long-term sites or 

locations? 

Are we picking sites based on a criterion like this rather than on a good exposure science basis? 

Do we want PM coarse samples for the sake of having a clean sample or are we sampling 

because there are exposure, source identification, or transport issue to be solved? This question 

is very strange. Without a clear set of objectives for what we are planning to use the data for, it 

is impossible to judge the value of the sites available. 

 55
2. If there is an opportunity to modify the NCore PM10-2.5 speciation monitoring requirements 

during a future rulemaking, should changes to the network design be considered? For example, 

changing the total number of required monitors and/or the required locations? 

Of course. At this point, when we have very limited knowledge of PM coarse, we are clearly 

going to make judgment calls that subsequent data will almost certainly tell us that some of our 

choices were wrong. We must always maintain flexibility in the network design. That was part 

of the NCore philosophy. 

 56
Multi-Filter Coarse Particle C

Speciation Sampler Using V

Objective:Develop a Coarse Particle ChemiSpeciation Sampler to Obtain FilteSamplers Similar to the Current FChemical Speciation Sampler UseEPA’s Fine Particle Monitoring Nethe Goal of Obtaining a Nearly CoMass Balance on the Collected C
Design

• Premise

– Need to Separate Fine and Coarse Particles for All 

• Better Understand Health Effects of PMc vs PMf• Source Apportionment• Not Mixing Fine and Coarse Chemistry (fine acidic, c

– Obtain Separation with a Virtual Impactor– Design Around the Current PMc and PMf FRM Flow 

Option for 6.7 LPM to Match the Current MetOne PSampler

– Include Design Flexibility for Additional Measureme

• Flexibility

– Allows Multiple Filters, Denuders, Back Up Filters a

Minimize Interferences

– Bypass Allows for Large Samples to Be Collected f

Testing, Organic Speciation, Trace and Ultra-Trace Including Valance States

– Virtual Impactor Can Have 5% Coarse, 95% Fine to 

Phase Artifacts on Coarse Filter*
Coarse

Particles

1000 LPM

Flo

16.7 

49.1 833 

byp

Existing Commercial High Volume Fine and Coarse Sampler Based on Virtual Impaction

Modified Sampler for PMc C

Design and Evaluation by Clarkson University and U.S. EPS Underway Currently. Commercialization by Greentech Environmental. Available Prototype for OAQPS Testing, May 15, 2009
Dr. Rudolf Husar 

PM10-2.5 Species or Components 

1. Table 1 provides a list of proposed PM10-2.5 species and analysis methods. Among these 

species, which are most important? Are there important PM10-2.5 species or components missing 

from this list? Are there important analysis methods missing from this list? 

No 

2. In the consideration of potential ion measurements for PM10-2.5 species, what ions should be 

on the target list? Are nitrate or ammonium ions important? If so, is an acid gas denuder and 

nylon filter required for the proper collection of these species in PM10-2.5? 

Nitrate is important 

3. The 2004 CD included a list of important PM10-2.5 components which included biological 

materials and fly ashes. If these species are important to characterize, what specific types of 

biological materials and fly ashes should be included? Is scanning electron microscopy (SEM) 

on Teflon filters sufficient to quantify and identify these species? Is the proposed total protein 

assay technique important to obtain a quantitative indicator of the total biological material 

present? 

Not familiar with bio aerosol sampling issues 

4. Can the complication of particle size and absorption effects in XRF be resolved using 

absorption correction factors? If not, what other method(s) should be considered? 

Saturation is real. Keep deposition density low? 

5. Are metal oxides a significant source of interference in thermal-optical analysis (TOA) of 

PM10-2.5 for OC and EC given the large expected soil component? If so, how should this 

interference be addressed? 

I am not familiar with oxides-OC/EC interference.

 60
Dr. Donna Kenski 

The questions on PM10-2.5 speciation measurement and on PM10-2.5 species or components are 

outside my areas of expertise and I respectfully defer to the distinguished panel members’ 

opinions on these subjects. With regard to network design, I’ve answered the charge questions 

below, but I feel compelled to note that, given the current lack of consensus on how best to 

sample for both PM10-2.5 mass and its speciated components, it seems much too premature to 

consider rolling out a network of 75 monitors by 2011, just 2 years from now. This is potentially 

a huge commitment of dollars and state resources that, once launched, will be very difficult to 

steer in a different direction if future developments warrant. The purpose of this pilot network is 

for research into coarse particle concentration distributions, sources, and health effects, which is 

commendable. But we need to allow enough time for the pilot results to be analyzed and filtered 

through the scientific community before launching a long-term network. A reasonable pilot 

network would be more like 5 or 10 sites where intensive sampling can take place (maybe even 

every day instead of every third day at some sites), characteristics of multiple monitors can be 

intercompared, and options for speciation of those multiple monitors can be explored and vetted 

until the research community has more collective confidence in the best way to move forward. 

If the purpose of speciation is to perform source apportionment, I agree with several panel 

members who have noted that the bulk components (OC, EC, ions, metals) will not be sufficient 

to separate some important sources of PM10-2.5. It is possible that organic carbon speciation 

would help resolve some of these sources. While this is unlikely to be feasible as part of the 

routine network, it should have a place in the pilot network since it would shed some light on 

whether source apportionment with the bulk species is able to resolve carbon sources 

satisfactorily. This should include source sampling for the PM10-2.5 fraction as well, although 

that’s not necessarily a network function. Continuous sampling for PM10-2.5 mass and 

components (at least EC/OC) would certainly be helpful as well. 

Network design

1. Are sites with high PM10 and low PM2.5 good candidate sites for PM10-2.5 speciation? Given that there 

will be some urban and rural NCore monitoring sites with PM10-2.5 speciation, what other factors should 

be considered in selecting the pilot monitoring and long-term sites or locations? 

One should aim for a selection of sites that represent varying ratios of PM10:PM2.5, as well as 

varying geographic distribution because the composition of both particle size fractions will vary 

geographically as well. It will be important to include both coastal and inland sites, urban and 

rural (not just pristine wilderness areas but agricultural areas also), and various meteorological 

regimes. It seems like most of the NCore sites as currently proposed are generally populationoriented PM2.5 sites. Sites that reflect maximum and representative PM10-2.5 exposures will not 

necessarily coincide with those PM2.5 sites, so the pilot program should have the flexibility to 

monitor at locations outside the NCore network. Based on data collected in the next few years, 

informed decisions could then be made about long-term sites. 

 61
2. If there is an opportunity to modify the NCore PM10-2.5 speciation monitoring requirements during a 

future rulemaking, should changes to the network design be considered? For example, changing the total 

number of required monitors and/or the required locations? 

Of course changes to the network should be continually under consideration; hopefully that’s an 

important objective of a pilot network. Learn what works and what doesn’t and adjust 

accordingly. As noted above, it seems much too soon to contemplate 75 speciation sites. I 

strongly encourage EPA to move ahead slowly and evaluate the pilot study data thoroughly 

before expanding the network beyond a handful of research sites. The resources spent on 

monitor and method intercomparisons will be a much better investment of our scarce monitoring 

dollars than a hasty move to monitor at all 75 NCore sites. Let the research community evaluate 

these results, come to agreement on speciation sampling and analysis protocols, then move 

forward with a broader network that’s truly science-based. 

 62
Dr. Thomas Lumley 

PM10-2.5 Species or Components 

1. Table 1 provides a list of proposed PM10-2.5 species and analysis methods. Among these 

species, which are most important? Are there important PM10-2.5 species or components 

missing from this list? Are there important analysis methods missing from this list? 

Distinguishing burning biomass (wood or grass) from other carbon sources with levoglucosan 

may be useful and relatively inexpensive. 

2. In the consideration of potential ion measurements for PM10-2.5 species, what ions should be 

on the target list? Are nitrate or ammonium ions important? If so, is an acid gas denuder and 

nylon filter required for the proper collection of these species in PM10-2.5? 

 Not my field. 

3. The 2004 CD included a list of important PM10-2.5 components which included biological 

materials and fly ashes. If these species are important to characterize, what specific types of 

biological materials and fly ashes should be included? Is scanning electron microscopy 

(SEM) on Teflon filters sufficient to quantify and identify these species? Is the proposed total 

protein assay technique important to obtain a quantitative indicator of the total biological 

material present? 

In areas where wood is used for heating, wood smoke is important to distinguish as there are 

straightforward ways to reduce emission. Specific allergenic pollen sources may be important 

when studying health effects of the coarse fraction. 

4. Can the complication of particle size and absorption effects in XRF be resolved using 

absorption correction factors? If not, what other method(s) should be considered? 

Not my field 

5. Are metal oxides a significant source of interference in thermal-optical analysis (TOA) of 

PM10-2.5 for OC and EC given the large expected soil component? If so, how should this 

interference be addressed? 

Not my field 

Network Design

1. Are sites with high PM10 and low PM2.5 good candidate sites for PM10-2.5 speciation? Given 

that there will be some urban and rural NCore monitoring sites with PM10-2.5 speciation, 

what other factors should be considered in selecting the pilot monitoring and long-term sites 

or locations? 

 

 63
Speciation will be relatively straightforward, especially by the difference method, in sites with 

high PM10 and low PM2.5. The sources and species contributing to the coarse fraction may well 

be different in sites with high PM10 and low PM2.5. If so, it would be important to also carry out 

speciation at other sites. It is entirely conceivable that most of the health impact of coarse PM 

occurs at sites with moderate coarse:fine ratios rather than at sites with high peak concentrations 

of wind-blown soil. The sites should be chosen to capture the range of types of coarse PM 

exposure in the population. 

2. If there is an opportunity to modify the NCore PM10-2.5 speciation monitoring requirements 

during a future rulemaking, should changes to the network design be considered? For 

example, changing the total number of required monitors and/or the required locations? 

It would be useful to add sites whose coarse-fraction composition is likely to be different from 

those already in the network, especially if large numbers of people may be exposed. While it is 

true that local sources have a larger contribution to coarse PM than fine PM, some of the highest 

levels of soil-based coarse PM will affect fairly large areas (not necessarily at the same time). 

Expanding the network is most useful when it captures qualitatively under-represented types of 

coarse PM. More monitoring in populated areas California and the Southwest is likely to be 

useful for understanding the health effects of coarse PM. Monitoring in areas with low 

population density may be informative about sources but is unlikely to be useful for studying 

health effects. 

 64
Dr. Peter H. McMurry 

PM10-2.5 Speciation Measurement

1. Table 1 provides a list of proposed PM10-2.5 species and analysis methods. Are there 

additional PM10-2.5 target species or methods that can be used to help identify the source of 

unidentified mass in order to obtain better mass closure? 

Biological material is a poorly understood category of particulate matter that is likely to be 

significant. Matthias-Maser and coworkers {, 2000 #11407} reported that during a complete year 

of sampling in the Lake Baikal region, “20% of the number concentration and almost 30% of the 

volume concentration were biological, with no seasonal variation.” While the carbon content of 

biological material ought to be detected by OC/EC analyses, it is important to identify the extent 

to which bioaerosols contribute to particulate mass if this is indeed such a major source. Fuzzi et 

al. {, 1997 #6836} reported that “the concentration of airborne bacteria and yeasts is enriched in 

foggy conditions up to two orders of magnitude compared to clear air conditions, while 

concentration of moulds is not influenced by the presence of fog,” suggesting that fog droplets 

act as culture media for biological particles. Mohler et al. {, 2007 #21265} report that biological 

particles may play an important role in cloud formation. Given the potential significance of 

biological particles in coarse particles, an effort should be made to quantify their contribution to 

mass. I am not sufficiently knowledgeable to provide useful input regarding suitable analytical 

methods. 

I agree with the concern expressed by several Committee members that OM/OC may be quite 

different for particles of biological origin, secondary OC, and primary. An effort must be mede 

to determine those ratios for biological particles. 

2. Various sampling devices, including dichotomous samplers, MetOne SASS speciation 

monitors, PM10 and PM2.5 FRMs are potential sampling devices (with the appropriate filter 

types) for PM10-2.5 speciation. Among these sampler types, which should be included or excluded 

from the pilot network design? Are there other sampling devices not listed here that should be 

considered? 

I would not favor the use of indirect methods such as the GRIMM optical detector. The 

correlations between GRIMM mass and gravimetric mass shown by Delbert Eatough in his 

remarks are extremely impressive. However, assumptions about shape, density, and refractive 

index must be made to convert optical signals to mass. In my experience, those aerosol 

properties vary with sampling time and location and will inevitably introduce uncertainties. 

I agree with Delbert Eatough’s comments that chemical interactions between fine and coarse 

particles could affect speciation measurements. This argues against using the PM10-2.5 FRM as 

the speciation sampler. However, it is also true that if a perfect sampler were used to obtain 

samples for speciation analysis, then it might not be possible to reconcile measured (FRM) mass 

and reconstructed mass. On the other hand, speciation measurements done on FRM samples 

could, in principle, produce mass closure. Is “truth” or “agreement” better? I am inclined to 

agree with Prof. Eatough: If a dichotomous sampler produces results that are more nearly “true,” 

 65
then it would be a preferable sampler. 

During our conference call Warren White pointed out another reason to inertially separate coarse 

and fine particles before collection. In previous meetings of this Committee, the point was made 

that coarse urban particles may contribute more to adverse health outcomes than coarse nonurban 

particles. This could be because urban coarse particles serve as carriers for toxic compounds 

picked up by exposure to the urban environment. If those toxic compounds were also present in 

fine particles at comparable or higher concentrations, then measurements by difference would 

lead to substantial uncertainties. 

3. What are the PM10-2.5 speciation sampling artifacts that may be encountered using the 

samplers mentioned above and how should they be addressed? Is speciation by the difference 

method problematic for PM10-2.5 speciation and if so what specific issues make it problematic? 

Volatilization and chemical reactions due to interactions of basic and acidic particles; inaccurate 

determination of the fraction of collected mass that is water. 

4. The current and most widely used PM2.5 speciation sampler is the MetOne SASS and it has a 

flow rate of 6.7 Liters per minute (Lpm) which is significantly lower than either the FRM for 

PM10-2.5 mass or the dichotomous sampler (16.7 Lpm). If this sampler was configured for PM10-

2.5 by difference, would the 6.7 Lpm flow rate be problematic, especially with the need to 

compare reconstructed mass to the mass collected by the PM10-2.5 FRM? 

I defer. 

5. Is the amount of particle mass collected on the dichotomous filters (especially the minor 

flow) sufficient for speciation chemical analysis? 

If the sampling rate into the dichot is 16.7 lpm, then the sampling rate for coarse particles would 

be the same as for the FRM. The dichot would offer the advantage that coarse and fine particles 

are not combined to the same extent as occurs on the FRM. 

PM10-2.5 Species or Components 

1. Table 1 provides a list of proposed PM10-2.5 species and analysis methods. Among these 

species, which are most important? Are there important PM10-2.5 species or components missing 

from this list? Are there important analysis methods missing from this list? 

I feel that highlighting coarse particles of biological origin is appropriate. I am not an expert on 

biological particles or on ways to detect them. Eric Edgerton has worked on this topic and made 

some interesting recommendations for chemical assays that might provide further information on 

biological particles. 

The document also suggested that SEM might be used for biological particles. Indeed, visual 

observations can provide useful insights into possible origins of particles. However, I am not 

familiar with automated SEM techniques that have proven reliable for providing the type of 

 66
quantitative information that might be expected for a monitoring network. I feel that limited use 

of SEM in research by knowledgeable persons should be encouraged. Sampling times and 

samplers should be optimized for this purpose. It seems unlikely that heavily loaded PM10 

samples would be optimal for SEM analysis. 

2. In the consideration of potential ion measurements for PM10-2.5 species, what ions should be 

on the target list? Are nitrate or ammonium ions important? If so, is an acid gas denuder and 

nylon filter required for the proper collection of these species in PM10-2.5? 

George Allen’s admonition that coarse particles are different from fine particles is important. As 

Bart Croes points out, nitrates (especially sodium nitrate) can be a significant coarse particle 

component, especially near the coast. Judy Chow’s point that magnesium can be a useful tracer 

for agricultural activities is also persuasive. 

3. The 2004 CD included a list of important PM10-2.5 components which included biological 

materials and fly ashes. If these species are important to characterize, what specific types of 

biological materials and fly ashes should be included? Is scanning electron microscopy (SEM) 

on Teflon filters sufficient to quantify and identify these species? Is the proposed total protein 

assay technique important to obtain a quantitative indicator of the total biological material 

present?

I do not see a clear reason for separating out fly ash as a source category. My other thoughts 

pertinent to this question are given above. 

4. Can the complication of particle size and absorption effects in XRF be resolved using 

absorption correction factors? If not, what other method(s) should be considered? 

I defer. 

5. Are metal oxides a significant source of interference in thermal-optical analysis (TOA) of 

PM10-2.5 for OC and EC given the large expected soil component? If so, how should this 

interference be addressed? 

I defer. 

Network Design

1. Are sites with high PM10 and low PM2.5 good candidate sites for PM10-2.5 speciation? Given 

that there will be some urban and rural NCore monitoring sites with PM10-2.5 speciation, what 

other factors should be considered in selecting the pilot monitoring and long-term sites or 

locations? 

Other committee members provided insightful responses to this question. 

 67
2. If there is an opportunity to modify the NCore PM10-2.5 speciation monitoring requirements 

during a future rulemaking, should changes to the network design be considered? For example, 

changing the total number of required monitors and/or the required locations? 

I defer. 

 68
Mr. Richard L. Poirot 

PM10-2.5 Speciation Measurement

1. Table 1 provides a list of proposed PM10-2.5 species and analysis methods. Are there 

additional PM10-2.5 target species or methods that can be used to help identify the source of 

unidentified mass in order to obtain better mass closure? 

Generally the list of proposed species seems OK, although if the difference method is being 

considered for sampling, this list may require more samplers than is feasible. It may not make 

sense to more or less duplicate the PM2.5 speciation analysis. Possibly it will be more efficient 

to include some relatively basic “screening” sampling at most coarse speciation sites , with more 

detailed analyses at selected sites and/or based on the screening analysis. I wonder how much 

useful information will really be provided by repeating the same TOR & TOT analyses (with the 

exact same thermal cut-points) for OC & EC? Some molecular level carbon analysis could be 

revealing at a few sites. A measurement of light absorption from Teflon dichot filters might be a 

useful, low cost addition to consider. Possibly the ion analysis may not require nylon filters or 

denuders, as we really don’t expect much coarse ammonium nitrate, nor are there really any very 

satisfactory ways to quantify ambient ammonium concentrations. I don’t know much about 

sampling for biological materials, but think there must be other useful options beyond SEM and 

Protein Assay. I’m not sure that SEM on Polycarbonate filters for fly ash can really be justified, 

except at sites where a substantial fly ash contribution is otherwise indicated. Possibly also some 

sort of toxicity testing might be conducted on (seasonally composited, coarse-only) samples to 

get a sense of which sites/seasons have the most harmful coarse particle mixtures. Then 

chemical &/or biological analyses could be focused to the samples of interest. 

Regarding mass balance issues, I think (assuming crustal oxides are appropriately estimated) that 

a large and likely variable fraction unmeasured of non-carbon organic matter could be a 

significant contributor to mass. For example the C:mass ratios for carbohydrates & cellulose are 

2.4 & 2.5, and carbonate – likely to be present in many coarse samples – has a C:mass ratio of 4. 

Rather than adding additional species in ambient sampling, it might be more efficient to analyze 

known quantities of different source material by comparable methods to get a better sense of 

how the easily measured species relate to the masses.

2. Various sampling devices, including dichotomous samplers, MetOne SASS speciation 

monitors, PM10 and PM2.5 FRMs are potential sampling devices (with the appropriate filter 

types) for PM10-2.5 speciation. Among these sampler types, which should be included or 

excluded from the pilot network design? Are there other sampling devices not listed here that 

should be considered? 

I think a sampler such as the one Phil Hopke suggests, that allows for both size-separated 

particles on multiple filter types, and also has the option to collect relatively large sample sizes to 

support other more detailed analyses could be useful to test in the pilot study. It could also be 

useful to evaluate different analyses on different filter media. For example, how does nitrate on 

coarse dichot quartz and Teflon compare with nitrate on (denuded) dichot Nylon? It would also 

 69
be useful to evaluate any continuous speciation instruments, such as the paired PM10 and PM2.5 

Sunset Labs carbon analyzers – vs filter samples. While there are so many benefits to the use of 

dichotomous samplers, one possible disadvantage is that the exposed coarse Teflon filters – 

without the sticky fines – may not “travel well”. Aside from just comparing samplers & filters, it 

might be useful to look specifically for potential sample loss from coarse dichot filters with 

rough handling, and to develiop best practices to minimize such losses (if any). 

3. What are the PM10-2.5 speciation sampling artifacts that may be encountered using the 

samplers mentioned above and how should they be addressed? Is speciation by the difference 

method problematic for PM10-2.5 speciation and if so what specific issues make it problematic? 

As indicated above, we really don’t expect much coarse ammonium nitrate or ammonium sulfate 

and so Nylon filters and denuders may not be needed (nor would ammonium measurements like 

reflect ambient concentrations). Coarse nitrate might be measured directly from Quartz or 

Teflon dichot filters. Loss of some chloride is likely from samples with sea salt or road salt. 

OC artifacts are likely to be proportionately less than for fine particle sampling, but a careful 

effort should be made to quantify OC blank concentrations. 

Speciation by difference should work reasonably well for any species with relatively high 

concentrations in the coarse mode, and poorly for any species with relatively high concentrations 

in the fine mode. 

4. The current and most widely used PM2.5 speciation sampler is the MetOne SASS and it has 

a flow rate of 6.7 Liters per minute (Lpm) which is significantly lower than either the FRM for 

PM10-2.5 mass or the dichotomous sampler (16.7 Lpm). If this sampler was configured for 

PM10-2.5 by difference, would the 6.7 Lpm flow rate be problematic, especially with the need to 

compare reconstructed mass to the mass collected by the PM10-2.5 FRM? 

This may be a concern, but I defer to others for an answer. One potential “advantage” for coarse 

speciation is that we are not starting out with a strong advance signal that the mass of coarse 

particles is a good health indicator. Achieving a mass balance is less important than 

understanding where the various components of coarse particles come from and which are most 

injurious to health (or welfare). 

5. Is the amount of particle mass collected on the dichotomous filters (especially the minor 

flow) sufficient for speciation chemical analysis? 

I don’t think this should be an issue, except for analyses such as molecular carbon compounds or 

specific biological components which may require very large sample sizes. 

PM10-2.5 Species or Components

1. Table 1 provides a list of proposed PM10-2.5 species and analysis methods. Among these 

species, which are most important? Are there important PM10-2.5 species or components 

missing from this list? Are there important analysis methods missing from this list? 

 70
See answers to Q 1 under Speciation Measurement Issues. My preference for a minimum Coarse 

speciation measurement (for the most sites) would be a dichot with XRF and optical absorption 

on a Teflon coarse filter. My next addition would be a dichot with quartz filters for carbon and 

ion analysis. Paired (difference method) or virtual impaction (coarse only) mass and OC/EC by 

continuous methods may also be a valuable complement to provide better time series 

information. Toxicity assays and/or molecular carbon analyses might be considered on 

seasonally-composited samples at some sites. 

Specific sampling and/or analyses for pollen – or pollen components (often fragmented into or 

aerodynamically acting like particles smaller than 10 microns) may be useful at some sites or 

seasons. Possibly, sampling for biological analyses may require other methods (see #3 below) for 

which absolute particle size cut is less critical than ability to culture or bioassay, and reasonable 

assumptions can be made about the domination of coarse mode formation or suspension 

mechanisms. 

2. In the consideration of potential ion measurements for PM10-2.5 species, what ions should 

be on the target list? Are nitrate or ammonium ions important? If so, is an acid gas denuder and 

nylon filter required for the proper collection of these species in PM10-2.5? 

See previous answers. I don’t see why there should be much coarse ammonium nitrate in the 

ambient air, and I expect coarse nitrate compounds (NaNO3, CaNO3, etc.) to be less volatile – 

and therefore likely not needing denuders or Nylon filters. But do the necessary experiments to 

confirm or disprove this in the pilot network. 

3. The 2004 CD included a list of important PM10-2.5 components which included biological 

materials and fly ashes. If these species are important to characterize, what specific types of 

biological materials and fly ashes should be included? Is scanning electron microscopy (SEM) 

on Teflon filters sufficient to quantify and identify these species? Is the proposed total protein 

assay technique important to obtain a quantitative indicator of the total biological material 

present? 

As previously indicated, I’m not sure fly ash SEM is generally warranted unless otherwise 

indicated. For more input on appropriate routine and/or at least occasionally feasible biological 

(sampling and) analyses, you may want to consult beyond this subcommittee. See for example 

Dale Griffin’s (USGS) paper on: Atmospheric Movement of Microorganisms in Clouds of 

Desert Dust and Implications for Human Health, Clinical Microbiology Reviews, July 2007, p. 

459-477, Vol. 20, No. 3, http://cmr.asm.org/cgi/content/full/20/3/459?view=long&pmid=17630335 

In the arid Southwest some specific analyses for Coccidioides fungi could be revealing. See for 

example Mark Bultman’s (USGS) poster at: 

http://www.fws.gov/southwest/Climatechange/poster%20pdfs/ValleyFeverPoster_Bultman.pdf 

As indicated above alternative sample collection may be warranted for certain kinds of biological 

analysis. 

4. Can the complication of particle size and absorption effects in XRF be resolved using 

absorption correction factors? If not, what other method(s) should be considered? 

 71
Not my area of expertise. I would imagine that reasonable correction factors can be developed. 

5. Are metal oxides a significant source of interference in thermal-optical analysis (TOA) of 

PM10-2.5 for OC and EC given the large expected soil component? If so, how should this 

interference be addressed? 

Not my area of expertise. I would imagine that reasonable correction factors can be developed. 

Network Design

1. Are sites with high PM10 and low PM2.5 good candidate sites for PM10-2.5 speciation? 

Given that there will be some urban and rural NCore monitoring sites with PM10-2.5 speciation, 

what other factors should be considered in selecting the pilot monitoring and long-term sites or 

locations? 

Sites with high coarse to fine ratios are likely to be dominated by crustal material, and will not be 

ideal places to evaluate strengths and weaknesses of different sampling and size-separation 

techniques. However, I think a few such sites should probably be included in both the pilot and 

longer-term networks and specifically include sites heavily influenced by: windblown dust, 

agricultural activities, mining activities and industrial process emissions. In the pilot study, it 

would also be useful to challenge the size separation methods by including sites with relatively 

high fine to coarse ratios. It would also be desirable to include sites intended to collect and 

characterize urban roadway emissions, in both arid and humid regions. Some effort might also 

be made in the pilot study toward understanding spatial variability and the differences in coarse 

concentration and composition that might be expected at NCore locations compared to locations 

closer to sources. A few rural coastal sites on the West Coast in the far Southeast – such as the 

Redwood, Point Reyes, Everglades or Virgin Island National Park IMPROVE sites – might be 

useful to best characterize the size distributions, chemical and biological content of Asian and 

African dust. 

2. If there is an opportunity to modify the NCore PM10-2.5 speciation monitoring requirements 

during a future rulemaking, should changes to the network design be considered? For example, 

changing the total number of required monitors and/or the required locations? 

Given the many questions & issues raised in the EPA staff memo and by the members of this 

review committee regarding sampling and analytical methods, analytes and site characteristics, it 

may not be possible or desirable to roll out a network of (identical) coarse speciation samplers at 

all 75 NCore locations by 1/1/11. I think the NCore concept was intended to be flexible, and that 

pending analysis of existing dichot data (for example from long-term California and Canadian 

studies), additional results from the current EPA (Bob Vanderpool) coarse particle monitoring 

sites, the planned pilot coarse speciation network, and other developments, it may be logical to 

consider changes to the proposed NCore coarse particle speciation network. 

Possibly, many of the NCore sites which are otherwise very well suited for assessment of 

multiple pollutant exposures may not be ideally sited for measuring coarse particle 

concentrations, compositions and representative exposures. I think it would be useful to 

 72
intentionally locate some coarse speciation sites in source-oriented locations, as indicated above. 

Along similar lines, it might make sense to plan for occasional “event analysis” of samples from 

many sites on days when certain source influences are otherwise evident – for example wild fires 

or prescribed agricultural burns, “local dust storms” from different regions, Asian or African dust 

storms, agricultural tilling, pollen or insect events, etc. Seasonal compositing of samples may 

also be a useful technique to allow more sophisticated measurements such as for molecular 

carbon compounds, which require large sample sizes or are too costly for routine application. 

I think an important complement to a coarse speciation network, and something that would 

enhance the value of existing fine speciation monitoring sites as well, would be to conduct an 

emissions characterization program in which source emissions are characterized by exactly the 

same sampling and analytical methods that are applied for ambient sampling (including both fine 

and coarse fractions which together provide better detail on sources). This might include a mix 

of direct emission sampling (with dilution / settling chambers) and “source oriented sampling – 

such as near roadway, etc. 

If a relatively large number of ambient monitoring sites is considered important, it might be 

useful to consider a “nested” network, with many sites initially taking a “minimal” set of 

measurements (for example 1 in 3 day dichots with Teflon filters and XRF and optical 

absorption analysis – or possibly a second dichot with quartz filters for carbon and ion analysis). 

Additional samplers, higher sample frequencies, continuous analyzers, and/or additional analyses 

might be added at smaller numbers of sites or to provide more detail at times and places where 

the initial measurements show interesting results. As suggested above, it might be informative to 

conduct some screening toxicity tests on seasonally composited samples to determine locations 

where more detailed chemical or biological sampling and analyses are most warranted. 

Although there was never sufficient funding provided to support NCore “Level 1 sites”, the 

concept is a good one and it might be especially applicable for coarse particle speciation 

monitoring, as it seems likely there will be a lingering need to develop and evaluate new 

sampling and analytical methods (at a few sites) even while less intensive “routine” coarse 

species monitoring is conducted at larger numbers of Level 2 sites. 

 73
Dr. Jay R. Turner 

Implementation of a monitoring network for coarse particle (PM10-2.5, called PMc in my 

comments) speciation will have many benefits including, but not limited to, information about 

emission sources and their relative contributions to burdens observed at the monitoring sites. 

The Agency is urged to make steady progress on the development and deployment of this 

network, but should also conduct the necessary pilot studies and ancillary evaluations (e.g. 

optimization of analytical methods) to ensure the network, when fully deployed, is robust in 

terms of sampling methodology and monitor siting. It might be necessary to make revisions to 

the pilot study design based on preliminary findings from the pilot network towards optimizing 

the measurement strategy. In my opinion, optimization of sampling hardware and monitor siting 

guidance (based on early results from the pilot network) should take precedence over meeting the 

January 1, 2011, date for full deployment of the PMc network at NCore sites. If the deployment 

date is delayed, the Agency should provide an explanation of the reason(s) for the delay, the 

remaining work to be done, and the revised timeline for network deployment. 

PM10-2.5 Speciation Measurement

1. Table 1provides a list of proposed PM10-2.5 species and analysis methods. Are there 

additional PM10-2.5 target species or methods that can be used to help identify the source of 

unidentified mass in order to obtain better mass closure? 

The species and analysis methods in Table 1 (amended from the white paper, and referring to the 

Agency presentation at the February 9 teleconference) meet two objectives – identifying the 

major chemical components needed to reconstruct PMc mass (as stated in the charge question) 

and providing additional information about emission sources and their relative contributions. 

Priority should be given to the analyses needed for mass balance closure and this subset of the 

list should contain the conventional analyses for gravimetric mass, water soluble ions, XRF 

elements, and carbon by thermal-optical analysis. Carbonate carbon will influence the OM/OC 

ratio but is expected to be important for only a limited number of environments. Thus, the 

carbonate carbon analysis is recommended for the pilot network but if it is expensive then it 

might be possible to include it at only a subset of sites in the full network. The protein analysis is 

also recommended for the pilot network with an evaluation of whether these data bring sufficient 

added value to be performed for the full network. 

2. Various sampling devices, including dichotomous samplers, MetOne SASS speciation 

monitors, PM10 and PM2.5 FRMs are potential sampling devices (with the appropriate filter 

types) for PM10-2.5 speciation. Among these sampler types, which should be included or excluded 

from the pilot network design? Are there other sampling devices not listed here that should be 

considered? 

All of these samplers have advantages and disadvantages as has been discussed in previous 

deliberations of this subcommittee. Paired PM10 and PM2.5 FRMs might be most challenged at 

sites with relatively high PM2.5 /PM10 ratios because the measurements uncertainties propagate 

for these independent measurements. This does not necessarily preclude the use of paired PM10

 74
and PM2.5 FRMs, but their suitability should be evaluated within the context of the DQOs and 

MQOs. For example, if source apportionment is an objective then the error structure in the data 

would be an important consideration. (We have a small data set of XRF elements for filter 

samples collected in St. Louis using paired PM2.5 and PM10 Harvard Impactors that can be shared 

with the Agency; it can be used to demonstrate limitations of the differencing method; there are 

additional data set, including sets collected by the Agency, which can be used to probe this 

issue). At this time, I give priority to dichotomous samplers. Historically, one concern has been 

the potential for losses from the coarse particle filters during handling and shipping since the fine 

particles present in a conventional PM10 sample act as “glue”. I recall the Agency examined this 

issue in their recent PMc characterization field campaign. If it is deemed an issue there might be 

simple ways to stabilize the deposit on the filters prior to shipping. Samplers with multiple 

sampling channels, such as used in the CSN network, are preferred because they allow the 

collection of particles on different filter media using a single sampler. However, the use of 

parallel samplers (a one sampler-one substrate approach), such as used in the IMPROVE 

network, has proven to be robust. In either case, the design should be sufficiently flexible to 

permit the use of upstream sample conditioning such as denuders. For mass balance closure, the 

low flow rate of the MetOne SASS speciation monitor should not be a major issue since the 

focus will be on the major chemical constituents. However, there could be issues with detection 

limits for the trace elements that are often important for emission source identification, especially 

if paired with XRF instead of ICP-MS.

3. What are the PM10-2.5 speciation sampling artifacts that may be encountered using the 

samplers mentioned above and how should they be addressed? Is speciation by the difference 

method problematic for PM10-2.5 speciation and if so what specific issues make it problematic? 

It will be helpful to understand how the virtual impactor cutpoint curve compares to the PM2.5

FRM cutpoint curve. The PM2.5 FRM impactor has been characterized in detail, and we know 

that the cutpoint curve is relatively broad (by design). The dichotomous sampler (or any other 

sampler being deployed) should also have a well-characterized cutpoint with this information 

ideally available when interpreting data from the pilot network, The white paper addresses 

potential artifact issues concerning carbon and nitrate; perhaps the nitrate is less of an issue if the 

counterion is not ammonium but rather sodium or potassium but it is not clear to me we can 

generalize our understanding of the chemical form of coarse PM nitrate based on the data 

collected to date. It would be ideal to evaluate the importance of denuders as part of the pilot 

network measurements. 

4. The current and most widely used PM2.5 speciation sampler is the MetOne SASS and it has a 

flow rate of 6.7 Liters per minute (Lpm) which is significantly lower than either the FRM for 

PM10-2.5 mass or the dichotomous sampler (16.7 Lpm). If this sampler was configured for PM10-

2.5 by difference, would the 6.7 Lpm flow rate be problematic, especially with the need to 

compare reconstructed mass to the mass collected by the PM10-2.5 FRM? 

The low flow rate for the MetOne SASS might indeed be an issue for trace elements if XRF is 

the de facto analytical method, further compounded if using the difference method. The low 

flow rate might be less of a concern if ICP-MS or a similar high-sensitivity method is used, but 

in this case there will be other tradeoffs regarding element-specific recoveries, cost, etc. 

 75
Certainly another layer of complexity is added when comparing reconstructed mass from 

samples collected at one flow rate to the mass collected by the PM10-2.5 FRM at a different flow 

rate, with this being more of a sampling artifact issue than a detection limit issue. 

5. Is the amount of particle mass collected on the dichotomous filters (especially the minor 

flow) sufficient for speciation chemical analysis? 

The minor flow still has all of the coarse PM pulled through the inlet (i.e. upstream of the virtual 

impactor).

PM10-2.5 Species or Components 

1. Table 1 provides a list of proposed PM10-2.5 species and analysis methods. Among these 

species, which are most important? Are there important PM10-2.5 species or components missing 

from this list? Are there important analysis methods missing from this list? 

The core species measurements should be elements, ions, and ECOC, consistent with the PM2.5

speciation network. A key issue is whether XRF can provide adequate data quality for some of 

the trace elements for conventional mass loadings on the filters. This is less of an issue for mass 

closure but might be important for source identification.

2. In the consideration of potential ion measurements for PM10-2.5 species, what ions should be 

on the target list? Are nitrate or ammonium ions important? If so, is an acid gas denuder and 

nylon filter required for the proper collection of these species in PM10-2.5? 

The target list for ions is reasonable. While conventional wisdom says a denuder is needed for 

high quality nitrate measurements, work performed for the IMPROVE program has shown that 

certain inlets can be quite effective denuding nitric acid (although I don’t know about the 

extrapolation of these results to urban environments). Sampling with and without denuders 

should be performed in the pilot network to determine whether they are warranted. Also, Nylon 

filters should certainly be used in the pilot network and then an evaluation can be made 

concerning the importance of ammonium nitrate. 

3. The 2004 CD included a list of important PM10-2.5 components which included biological 

materials and fly ashes. If these species are important to characterize, what specific types of 

biological materials and fly ashes should be included? Is scanning electron microscopy (SEM) 

on Teflon filters sufficient to quantify and identify these species? Is the proposed total protein 

assay technique important to obtain a quantitative indicator of the total biological material 

present? 

I do feel strongly that we need a better characterization of the bioaerosol component. However, I 

have no specific comments on the method. Analysis for fly ash by SEM could be insightful, but 

perhaps used only in cases where trace element compositions suggest there are potentially 

significant fly ash contributions to PMc (I repsct there might be some issues in teasing out a fly 

ash signature from a soil signature from the elemental data). 

 76
4. Can the complication of particle size and absorption effects in XRF be resolved using 

absorption correction factors? If not, what other method(s) should be considered? 

I leave this question to those colleagues with more expertise than me on this matter. 

5. Are metal oxides a significant source of interference in thermal-optical analysis (TOA) of 

PM10-2.5 for OC and EC given the large expected soil component? If so, how should this 

interference be addressed? 

It is generally accepted that the presence of such compounds can dramatically shift the carbon 

evolution profile during thermal analysis – whether this leads to errors in the EC/OC split is not 

clear. While not focusing on PMc, one option might be to examine data collected from 

continuous ECOC instruments in environments with high metal oxide loadings. Does the 

relationship between thermal EC and optical EC change in time with increasing time after a 

clean filter has been installed (presumably some of the metal oxides will remain on the filter and 

accumulate in time). 

Network Design

1. Are sites with high PM10 and low PM2.5 good candidate sites for PM10-2.5 speciation? Given 

that there will be some urban and rural NCore monitoring sites with PM10-2.5 speciation, what 

other factors should be considered in selecting the pilot monitoring and long-term sites or 

locations? 

The focus should not be exclusively on sites with high PM10 and low PM2.5. The pilot sites 

should be chosen to represent a broad range of aerosol compositions and environmental 

conditions, with the results being used to refine the recommendations for which Ncore sites 

should have PMc speciation. There are other considerations, such as providing data sets of use to 

health scientists, which would support the selection of sites to collectively include a range of 

PMc levels. 

2. If there is an opportunity to modify the NCore PM10-2.5 speciation monitoring requirements 

during a future rulemaking, should changes to the network design be considered? For example, 

changing the total number of required monitors and/or the required locations? 

See my introductory comment which addresses the timeline for network deployment. At this 

point, I have no additional comments about the network design. 

 77
Dr. Warren H. White 

PM10-2.5 Speciation Measurement

I will start by recognizing, and commending, the Agency’s early consultation with this 

committee and its plan to start with a pilot study. An eventual network of 75 sites sampling at 

least one day in every three will represent a huge commitment of resources that might otherwise 

be devoted to more time-resolved measurements, or to biochemical assays and other new 

approaches to sample characterization, or to nuclei counters and other instruments more 

responsive to ultra-fine particles. Any one of these alternatives to the straightforward extension 

to PM10-2.5 of current PM2.5 measurements might yield greater insight into which particles should 

be of greatest concern to regulators. I urge the Agency to delay the general introduction of PM10-

2.5 monitoring at NCore sites until the pilot study has had adequate time to develop, explore, and 

assess a variety of sampling and analytical methods. 

“Since EPA is requiring PM10-2.5 speciation monitoring primarily for scientific purposes...” 

It’s not at all clear to me what those scientific purposes would be – source attribution? 

Assessment of hazardous components as called for by the NRC (2004)? The methods under 

discussion, largely derived from the existing PM2.5 speciation network, don’t seem very well 

adapted to either of these. 

Source attribution: We have considerable experience with source attribution using speciated 

PM2.5 data. That experience has taught us that it is hard to distinguish between different 

carbonaceous sources using EC and OC from thermal-optical analysis, and that it is hard to 

distinguish between different sources of dust using elemental analysis. But organic and crustal 

materials make up the bulk of PM10-2.5 nearly everywhere. So what can the proposed level of 

speciation do? It can distinguish smoke from dust, but how often do local agencies encounter 

high PM10-2.5 that they can’t easily associate with obvious local and regional sources of smoke or 

dust? 

Hazard assessment: Its 2005 assessment of the epidemiological evidence lead EPA to 

“consideration of thoracic coarse urban particulate matter (UPM10–2.5) as an indicator for a 

thoracic coarse particle standard ... qualified so as to include any ambient mix of PM10–2.5

that is dominated by resuspended dust from high-density traffic on paved roads and PM 

generated by industrial sources and construction sources, and to exclude any ambient mix of 

PM10–2.5 that is dominated by rural windblown dust and soils and PM generated by 

agricultural and mining sources.” 

In other words it judged that dusts of crustal origin, benign in rural settings, became 

contaminated in cities with surface coatings and other urban grime. It will be hard to detect such 

trace contaminants in PM10-2.5 samples with the bulk chemical analyses currently used with 

PM2.5; it will be still harder against a background of chemically-similar PM2.5 mixed in with a 

PM10 sample. The pilot study should give particular attention to analytical methods that can 

target specific fractions expected to be enriched in PM10-2.5, such as biological markers. 

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Reference

NRC (2004) Research Priorities for Airborne Particulate Matter IV: Continuing Research 

Progress. National Academies Press, Washington. 

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Dr. Yousheng Zeng 

PM10-2.5 Speciation Measurement

Among the four filter-based sampler types, dichotomous samplers should be used for speciation 

measurement. Dichotomous samplers produce physically separate coarse samples for speciation 

chemical analysis, which in turn reduces interferences and complications. They have been used 

for long time and are better understood. 

Although the difference method is FRM for coarse particle mass measurement, it may not be 

most suitable for speciation measurement. When the levels of a component (or species) in the 

PM2.5 sample and PM10 sample are close (i.e., the component primarily associated with PM2.5), 

the difference between the two measurements may be too small compared to analytical 

uncertainty, making the speciation measurement unreliable. This problem is more significant 

when the chemical analysis has a sufficient method detection limit, but poor precision 

(repeatability). In that case, if dichotomous samplers are utilized, the results will be more 

reliable. 

Even though dichotomous samplers are not FRM for PM mass measurement, their deviation 

from FRM, if any, is small. Considering uncertainties associated with many chemical analyses 

at low concentration levels, this possibly small deviation should be acceptable. 

PM10-2.5 Species

Speciation for organic portion seams lacking. If feasible, it would be useful to analyze for semivolatile organic species and parameters typically obtained in ultimate analysis. The semi-volatile 

organic species should be useful in source apportionment. Also, ultimate analysis may help 

close the mass difference. I am not sure this will be feasible or practical. I just want to bring this 

up for EPA to consider for the pilot sites. 

Network Design

For selection of pilot sites, high PM10 and low PM2.5 sites should give more PM coarse fraction 

to work with. However, I think it is also important to select some pilot sites that represent low 

PM10 and high PM2.5. At these sites the PM coarse fraction would be low. It would be a good 

test to see how the speciation methods perform when the coarse fraction is low (e.g., will method 

detection limits be low enough to cover some important species). Also, when EPA considers 

high or low PM10 or PM2.5, EPA should consider not only the ratio between PM10 and PM2.5, but 

also the mass levels of PM10 and PM2.5. Both high mass level and low mass level sites should be 

included in the pilot program to fully assess candidate speciation methods. 

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Dr. Barbara Zielinska 

PM10-2.5 Speciation Measurement 

1. Table 1 provides a list of proposed PM10-2.5 species and analysis methods. Are there 

additional PM10-2.5 target species or methods that can be used to help identify the source of 

unidentified mass in order to obtain better mass closure? 

In my opinion, Table 1 is missing the speciation of PM10-2.5 organic compounds. Taking into 

account that organic carbon (OC) constitutes significant portion of PM10-2.5 mass, it is essential to 

have a general understanding what species comprise this organic mass. Are these species mostly 

of biogenic origin, biological material, or perhaps also anthropogenic? This knowledge may 

have important health implications and so far is missing. Since the primary objective for PM10-2.5 

speciation data is to support further research in understanding their chemical composition and 

source, the importance of the organic mass speciation should not be overlooked. It may help in 

source apportionment and in determining OM/OC factor. The organic mass speciation should be 

attempted during pilot study phase in some selected NCore sites that are representative of urban 

and rural settings. The EPA should not specify target organic compounds to be quantified (as it 

has been done so far), but should require the identification of as many organics as possible to get 

some knowledge of the organic mass composition of coarse particles in different locations. PM10-

2.5 is very different from PM2.5 and the source tracers that worked for fines may not work for 

coarse particles. 

2. Various sampling devices, including dichotomous samplers, MetOne SASS speciation 

monitors, PM10 and PM2.5 FRMs are potential sampling devices (with the appropriate filter 

types) for PM10-2.5 speciation. Among these sampler types, which should be included or excluded 

from the pilot network design? Are there other sampling devices not listed here that should be 

considered? 

PM10 and PM2.5 FRM are not appropriate for speciation of PM10-2.5, since when the fine and 

coarse particles are mixed together, their composition can be potentially altered. Also, the 

determination of chemical composition by a difference method is inherently less precise and it is 

virtually impossible for organic compound’s speciation. Although volatility issues are likely less 

important for PM10-2.5, they are important for PM2.5, which may bias the results of the difference 

method. Dichotomous sampler (or equivalent), which provides a separate PM10-2.5 fraction are 

more appropriate for chemical speciation. 

In addition, continuous methods for mass measurements and OC/EC speciation should be 

encouraged. 

3. What are the PM10-2.5 speciation sampling artifacts that may be encountered using the 

samplers mentioned above and how should they be addressed? Is speciation by the difference 

method problematic for PM10-2.5 speciation and if so what specific issues make it problematic? 

See my answer to Question #2. 

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4. The current and most widely used PM2.5 speciation sampler is the MetOne SASS and it has a 

flow rate of 6.7 Liters per minute (Lpm) which is significantly lower than either the FRM for 

PM10-2.5 mass or the dichotomous sampler (16.7 Lpm). If this sampler was configured for PM10-

2.5 by difference, would the 6.7 Lpm flow rate be problematic, especially with the need to 

compare reconstructed mass to the mass collected by the PM10-2.5 FRM?

As stated above, I do not recommend speciation by the difference method. Dichotomous 

sampler with 16.7 Lpm flow rate is a better choice. 

5. Is the amount of particle mass collected on the dichotomous filters (especially the minor 

flow) sufficient for speciation chemical analysis? 

Since the total mass collected in the minor flow channel is a function of the inlet flow, this 

should not be a problem. 

PM10-2.5 Species or Components 

1. Table 1 provides a list of proposed PM10-2.5 species and analysis methods. Among these 

species, which are most important? Are there important PM10-2.5 species or components missing 

from this list? Are there important analysis methods missing from this list? 

Speciation of organic compounds is missing (see my answer to question #1 above). Such 

speciation is important from health effects point of view, as well as source attribution and mass 

closure. 

2. In the consideration of potential ion measurements for PM10-2.5 species, what ions should be 

on the target list? Are nitrate or ammonium ions important? If so, is an acid gas denuder and 

nylon filter required for the proper collection of these species in PM10-2.5? 

I don’t think an acid gas denuder or nylon filters are required. The ions and their analysis 

methods listed in the corrected Table 1 (slide #9 in Joann Rice presentations) seem to be 

adequate 

3. The 2004 CD included a list of important PM10-2.5 components which included biological 

materials and fly ashes. If these species are important to characterize, what specific types of 

biological materials and fly ashes should be included? Is scanning electron microscopy (SEM) 

on Teflon filters sufficient to quantify and identify these species? Is the proposed total protein 

assay technique important to obtain a quantitative indicator of the total biological material 

present? 

Fly ashes may only be important at sites close to some local sources (fly ashes were removed 

from Table 1 presented by Joann Rice). SEM on Teflon filters is not ideal for identification of 

biological materials - polycarbonate filters are better. Total protein assay may be important as an 

indicator of allergens, fragments of bacteria, etc. However, this assay is not adequate as an 

indicator of the total biological material present. Plant or soil derived material may be an 

important contributor. Analysis of sugars, sugar alcohols, phytosterols, triterpenoids, etc., may 

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help in quantification and identification of types of biological materials present in coarse 

particles. 

4. Can the complication of particle size and absorption effects in XRF be resolved using 

absorption correction factors? If not, what other method(s) should be considered? 

It would be desirable to compare ICPMS with XRF during a pilot study to answer this question. 

5. Are metal oxides a significant source of interference in thermal-optical analysis (TOA) of 

PM10-2.5 for OC and EC given the large expected soil component? If so, how should this 

interference be addressed? 

Metal oxides, if present in significant amounts may affect OC/EC split, however total carbon 

should not be affected. Humic material or carbonates are another potential interfering species. 

This question should be addressed during a pilot study. 

Network Design

1. Are sites with high PM10 and low PM2.5 good candidate sites for PM10-2.5 speciation? Given 

that there will be some urban and rural NCore monitoring sites with PM10-2.5 speciation, what 

other factors should be considered in selecting the pilot monitoring and long-term sites or 

locations? 

It would be important to include both types of sites, with low and high PM10 to PM2.5 ratios. 

Especially in urban locations and/or close to highways both types may be important. Variations 

in geographical distribution, costal and inland locations, urban and rural sites, proximity of 

mining sources, etc., should also be considered. 

2. If there is an opportunity to modify the NCore PM10-2.5 speciation monitoring requirements 

during a future rulemaking, should changes to the network design be considered? For example, 

changing the total number of required monitors and/or the required locations? 

Flexibility was one of the major components of NCore design, so yes. However, prior to 

implementing 75 PM10-2.5 speciation sites, the throughout evaluation of pilot study data should be 

completed. It seems that a goal of launching long-term PM10-2.5 network by 2011 is not very 

realistic. We should learn first what works and what doesn’t and allow enough time for scientific 

community to evaluate pilot study data and come to a consensus regarding the best methods of 

coarse particles monitoring and speciation.