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 Committ ee (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 speci ation sampling for coarse particles (PM 10-2.5 ). When EPA issued the final rule to revise both the primary and secondary N AAQS for particulate matter (PM) in October 2006, a new Federal Reference Method (FRM) was also pr omulgated for measuring the mass concentration of

PM 10-2.5 in ambient air. As part of the revisions to the Ambient Air Monitoring Regulations, PM 10-2.5 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 PM 10-2.5 and its speciated components; and the haste w ith which the Agency is committed to launch

the PM 10-2.5 monitoring network without sufficient time to anal yze the data from the pilot study. As this is a consultation, we do not expect a formal respon se from the Agency. We th ank the Agency for the opportunity to provide advice in the NAAQS review process.

Sincerely,

/Signed/

Dr. Armistead (Ted) Russell, Chair

CASAC AAMMS

Enclosures2 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 Mi chigan 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, Atmospheri c 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 Ai r Resources, Bureau of Air Quality Surveillance, New York State Department of Environmental Conservation, Albany, NY

Dr. Philip Hopke , Bayard D. Clarkson Distinguished Pr ofessor, Department of Chemical Engineering, Clarkson University, Potsdam, NY

Dr. Rudolf Husar , Professor, Mechanical Engineeri ng, 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, NY3 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 Pollutio n Control Division, Department of Environmental Conservation, Vermont Agency of Natural Resources, Waterbury, VT

Dr. Kimberly A. Prather ,* Professor, Department of Chemis try 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 Nu clear Laboratory, University of California - Davis, Davis, CA

Dr. Yousheng Zeng , Air Quality Services Director, Pr ovidence Engineering & Environmental Group LLC, Baton Rouge, LA

Dr. Barbara Zielinska , Research Professor, Division of At mospheric Sciences, Desert Research Institute, Reno, NV

SCIENCE ADVISORY BOARD STAFF Ms. Kyndall Barry , Designated Federal Officer, 1200 Penns ylvania 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 ................................................................................................................. 815 5 

### Mr. George Allen

PM 10-2.5 Speciation Measurement

1. Table 1 provides a list of proposed PM 10-2.5 species and analysis methods. Are there

additional PM 10-2.5 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 Tabl e 1 from the white paper. Other species: None that I am aware of; uncerta inties in OC (estimated) mass measurements (there are many) may be part of the missing mass puzzle. Met hods: 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 filte r. 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 dichot omous samplers, MetOne SASS speciation
monitors, PM 10 and PM 2.5 FRMs are potential sampling devices (with the appropriate filter types) for PM 10-2.5 speciation. Among these sampler types, wh ich should be included or excluded from the pilot network design? Are there other sa mpling devices not listed here that should be

considered?

For PM-coarse, I strongly recommend using onl y 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 th e 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 PM 10-2.5 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 PM 10-2.5 speciation and if so what specif ic issues make it problematic?

There are the usual fuzzy issues with OC artifac ts, 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) be fore 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 alkalin e crustal components. The latter may be

more dominant.

Speciation by difference is strongl y discouraged. Any species that is primarily in the fine mode,6 6 such as sulfate, will be difficult to measure w ith useful precision by a difference method that is run routinely in SLT networks. This would be looking at a small diffe rence 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. A llen, Jung-a Annie Oh, and Petros Koutrakis, Journal of the Air & Waste M anagement 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 “r esearch-grade” conditions, routine netw orks are unlikely to provide this level of precision. Also, alt hough the difference method can work well for PM when great care is taken to insure high precision, it remains unclear if analytical techniqu es for speciation can be made as precise as mass measurements wit hout excessive cost in a routine network.

4. The current and most widely used PM 2.5 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

PM 10-2.5 mass or the dichotomous sampler (16.7 Lpm). If this sampler was configured for PM 10-

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 PM 10-2.5 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 a lthough the coarse channel flow is only 1.67 Lpm, the coarse channel dichot f ilter includes (in theory) all the coarse particles present in the 16.7 inlet flow. Thus , the low flow for the coarse ch annel 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 no t relevant. Another important parameter for evaluation of dichot performance is the filter diameter - it does not ha ve to be 47 mm. The early dichots used 37 mm filters (33 mm exposed area). If enhanced load ing 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 coar se 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 demonstrat ed that shipping does not cause mass loss; early work by Spengler and Thurston showed shipping lo ss 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 fr om 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 wa s not reported and it is not clear if the original weighi ngs were done before any shipping of the filters had occurred. My conclusion is that shipping can be an issue for coarse channel dichot fi lters; 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.

PM 10-2.5 Species or Components

1. Table 1 provides a list of proposed PM 10-2.5 species and analysis methods. Among these species, which are most impor tant? Are there important PM 10-2.5 species or components missing from this list? Are there important an alysis 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 bioaeros ols. One aspect of pm-coarse speciation not on this list is particle surface composition. For coarse mode pa rticles, the surface com position -- 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 ma ss, 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 pr ofile that goes higher than 580Chelium only can give a reasonably useful indication of carbonate ca rbon. Carbonate comes off as a sharp peak between 700-750 C, during the tr ansition from 615 to 870 C, the highest helium only temperature used in the Suns et Labs laboratory carbon analyzer protocol. With some care,

the modest amount of OC that comes off in th is 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 poten tial ion measurements for PM 10-2.5 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 PM 10-2.5 ?

The ions listed are appropriate, with th e 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 PM 10-2.5 components which included biological materials and fly ashes. If these species are im portant to characterize, what specific types of biological materials and fly ashes should be incl uded? 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 significa nt 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 abs orption effects in XRF be resolved using absorption correction factors? If not, w hat 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 dic hot filter, and different [and imprecise] absorption correction factors would need to be used, re sulting in additional coarse-mode by difference errors. Absorption correction factors are more pract ical for dichot filters. Still, ICPMS should be considered as an alternative analysis tec hnique for acid/water solubl e components since it is

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

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

PM 10-2.5 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 ca n 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 am ount of “pre-oxidation”. Howeve r, another potential issue with TOA is interference from biogenic coarse mode hu mic material; it may have some absorption of the ~660 nm wavelength used for pyr olysis correction. If biogenic mass is much greater than EC mass, the interference could be significant.

Network Design

1. Are sites with high PM 10

and low PM 2.5 good candidate sites for PM 10-2.5 speciation? Given that there will be some urban and rural NCore monitoring sites with PM 10-2.5 speciation, what other factors should be consider ed in selecting the pilot mon itoring and long-term sites or

locations?

If a site’s PM10 is nearly all coarse-mode on a ma ss basis, it still may be useful to do dichotbased pm-coarse speciation. Some species of in terest 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, si nce that is needed for health studies to properly account for any lag effect.

2. If there is an opportunity to modify the NCore PM 10-2.5 speciation monitoring requirements during a future rulemaking, should changes to th e 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 ur ban pm-coarse; siting must be urban scale to be useful. It may be appropriate to have a second ur ban site (traffic oriented?) with at least limited speciation at mid-scale locations near sources ofcoarse PM. Results from the EPA-funded PMcoarse STAR grant projects on “Sources, Compositi on, and Health Effects of Coarse Particulate

Matter” http://cfpub.epa.gov/ncer_abstracts/index.cfm/fus eaction/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 fr om 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 201 1. At the least another year, pe rhaps 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-c oarse 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

PM 10-2.5 Speciation Measurement

1. Table 1 provides a list of proposed PM 10-2.5 species and analysis methods. Are there

additional PM 10-2.5 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 li st of elements, ions, carbon, and bioaerosol

indicators. Additional PM 10-2.5 species (e.g., filter light transmission [b abs ] and organic species)

can be measured to assist in health assessmen t 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 PM 10-2.5 mass is unaccounted for. The sum of species is not a good indicator for PM 10-2.5 mass closure calculations, since crustal material accounts for the major portion of PM 10-2.5 . A material balance that commonly groups by source types (e.g., geological material, secondary inorga nic aerosols, carbon, salt, and others) may be a better way to evaluate mass closure.

There are two major sources of uncertainties in PM 10-2.5 mass closure calculations: 1) assumptions about the form of metal oxides presen t 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 ge ological 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 PM 10-2.5 , with 7–15% organics. The unidentified mass was negligible (<1%) at six ur ban locations in Mexico City. PM 10-2.5 mass concentrations were high and variable, ranging from 19 to 56 μg/m 3 . The nature of OM is expected to be

different between PM 2.5 and PM 10-2.5 . 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 PM 10-2.5 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/O M. These measurements can be compared with

solvent extraction or other ca lculation 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 dichot omous samplers, MetOne SASS speciation
monitors, PM 10 and PM 2.5 FRMs are potential sampling devices (with the appropriate filter types) for PM 10-2.5 speciation. Among these sampler types, which should be included or excluded from the pilot network design? Are there other sa mpling devices not listed here that should be

considered?

Collocated BGI PQ2000 PM 2.5 and PM 10 samples have been designated as PM 10-2.5 FRM (U.S.EPA, 2008). Nevertheless, all filte r samplers with well-characterized PM 2.5 and PM 10 inlets

should be considered. The PM 10 sampling efficiency (Keywood et al., 1999; Watson et al., 1983; Wedding and Carney, 1983) is most important becau se the ambient size di stribution often peaks near the 10 μm cut-point (B urton and Lundgren, 1987; Lundgren et al., 1984; Lundgren and Burton, 1995). Since PM 10 and PM 10-2.5 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., th e BGI OMNI and the Airmetrics MiniVol) to allow more of them to be deployed, especially fo r short-term studies. These 5 L/min units have well-characterized inlets. These filter samplers can be collocated with PM 10-2.5 FRM.

To detect short-duration events, optical particle count ers (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 PM 2.5 , and R&P 2300 samplers). Sampling efficiencies should be estimated based on sampling effectiveness curves and anticipated size dist ributions at potential monitori ng locations prior to conducting collocated sampler comparisons. It will be important to verify the homogeneity of PM 10-2.5 levels across the sampling array (Mathai et al ., 1990) using similar instruments for a valid comparison study.

3. What are the PM 10-2.5 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 PM 10-2.5 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 en tire 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 coll ected per unit of filter area. A better understanding of the adsorbed compounds will be needed to go beyond current

PM 2.5 practices that can also be applied to PM 10-2.5

. Nitrate is less likely to evaporate from the coarse fraction as it does for PM 2.5 (Ashbaugh and Eldred, 2004; Chow et al., 2002b; 2005). PM 10-2.5 nitrate often occurs as non-volatile sodium nitrate (Mamane and Gottlieb, 1992; Mamane a nd Mehler, 1987; Wu and Okada, 1994). While12 12 there is abundant nitric acid in the atmosphere, it may react with alkaline PM 10-2.5 (Goodman et al., 2000; Hodzic et al., 2006; Laskin et al., 200 5; Ooki and Uematsu, 2005; Umann et al., 2005; Underwood et al., 2001), thereby resulting in a po sitive nitrate artifact for non-denuded samples

at certain locations.

Collocated PM 10 /PM 2.5 samplers and virtual impactor (dic hotomous) samplers require difference

calculations for which the uncerta inties of the individual sample s should be propagated (Evans and Ryan, 1983; Watson et al., 2001). The propagate d uncertainties of differences are about the

same for collocated PM 10 /PM 2.5 samplers, and may be higher for the dichotomous samplers

because the 10 to 1 flow rate ratio between the fi ne and coarse channels often varies. As pointed out by Allen et al. ( 1999), variability in PM 10-2.5 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, 199 5; Chow et al., 2008 for study summaries) have compared PM 2.5 and PM 10 separately. PM 10 comparisons are often poorer than those for PM 2.5 when: 1) PM 10-2.5 constitutes a large fraction of the PM 10 ; 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 PM 2.5 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

PM 10-2.5 mass or the dichotomous sampler (16.7 Lpm). If this sampler was configured for PM 10-

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 PM 10-2.5 FRM?

The MetOne SASS with a flow rate of 6.7 Lpm should be adequate to collect enough PM 10-2.5 for analysis in urban networks when equipped with a 6.7 Lpm PM 10 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 artif acts 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 e xplored. This is more of a PM 2.5 than a PM 10-2.5 issue, however. The MetOne SASS filter holder is costly to obtain, pro cess, and ship, and greater operational savings might be obtained by using a simpler sampler pa ir (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 di chotomous sampler is not an issue, since PM 10-.2.5 is taken from the 16.7 Lpm drawn through the PM 10 inlet. The dichotomous sampler with either

a PM 15 or PM 10 initial inlet has been used since the mid to late 1970s. The Harvard Six-City Study used elemental analysis by XRF on dichotom ous sampler filters for health assessments13 13 (e.g., Ferris, Jr. et al., 1979; Spengler et al ., 1983; Spengler and T hurston, 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 PM 2.5 and PM 15 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 (NO 3 - , SO 4 = ) speciation. The California Air Resources Board (ARB) also operated dichotomous (Andersen 244) sa mplers from 1983–2001 at 20 urban sites with elemental analysis for 30 species on both PM 2.5 and PM 10-2.5 samples (Motallebi et al., 2003a; 2003b; 2003c). There are several previous studie s 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, 2 002; 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). PM 2.5 and PM 10-2.5 mass and chemical data should

be assembled and evaluated to better understa nd the nature and chemical composition of PM 10-

2.5

. For very low loading PM 10-2.5 samples, the analytical instrument for XRF analysis and extraction volume for ion chromatography (IC) can be optimi zed to improve the minimum detectable limits (MDLs).

PM 10-2.5 Species or Components

1. Table 1 provides a list of proposed PM 10-2.5 species and analysis methods. Among these species, which are most impor tant? Are there important PM 10-2.5 species or components missing from this list? Are there important an alysis methods missing from this list?

PM 10-2.5 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., NO 3 - ) and carbon (e.g., OC and carbonate) are also important PM 10-2.5 components to be considered.

Without acidification for carbonate analysis, the presence of carbona te could bias both OC and EC measurements (Chow and Watson, 2002). Cao et al. (2005) found carbonate accounted for

8% of PM 2.5 mass during Asian dust storms, and ~5% be tween storms in Xian, China. Although

PM 2.5 carbonate may be negligible at non-urba n IMPROVE sites (Chow and Watson, 2002), its abundances may be important in PM 10-2.5 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, ca talytic influences of other mate rials, particle size, rate of heating, and the atmosphere surrounding the mate rial 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 h eating 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 dolom ite peak by -235 to 40 °C, as14 14 shown in Table A.

Figure A. Differential Thermal Analyses (DTA) curves for: A) typical cal cite (Faust, 1950); B) aragonite (Faust, 1950); C) natural calcite; D) sample giving curve C, calcined, hydrated, and partially recarbonated (fro m Webb and Krüger, 1970).

Figure B. Differential Thermal Analyses (DTA) curv es 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” temp erature of the first dolomite peak (Murray et al., 1951, from Webb and Krüger, 1970).

Organic carbon in urban and rural PM 10 road dusts and agricultural soils ranges from 3–20% (Chow et al., 2003). There is growing evidence th at coarse particle organic markers differ from

those for PM 2.5 and can be used to identify and quan tify 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 organi c species (e.g., polycycli c 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 organi cs (e.g., n-alkanes, alkenes, hopanes, steranes, PAHs; Chow et al., 2007; Hays and Lavrich, 200 7; Ho et al., 2008; Ho and Yu, 2004; Yang et al., 2005)

Coarse particles, especially minerals, have diffe rent light absorption char acteristics at different wavelengths that can be used to distinguish amo ng sources (Fialho et al., 2005; Kim et al., 2004). Filter light transmission (or b abs ) has been shown to be highly correlated with PM 2.5 or PM 10 EC and can serve as a surrogate for PM black carbon (BC). PM 10-2.5 b abs measurements at various wavelengths might be considered, especially for locations where only Teflon-membrane filter samples will be collected.

2. In the consideration of poten tial ion measurements for PM 10-2.5 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 PM 10-2.5 ?16 16 The anions (i.e., Cl - , NO 3 - , and SO 4 = ) and cations (i.e., Na + , Ca ++ , K + , NH 4 + ) listed in the revised

Table 1 should all be measured.

Coarse particle NO 3 - (e.g., sodium nitrate [NaNO 3 ]) has been found in the desert southwest and environments with abundant coarse PM (Mam ane and Mehler, 1987; Watson et al., 1994). Chemical reactions convert sodium chloride (N aCl) to hydrochloric ac id (HCl) and thermally

stable NaNO 3 (e.g., Ellis et al., 1983; Pili nis and Seinfeld, 1987; Russe ll and Cass, 1984). These reactions may dominate coarse particle NO 3 - and occur when NaCl from sea salt, road sanding, or dry lake beds is an abundant atmos pheric constituent. Since most of the PM 10-2.5 contains alkaline crustal material, it is not necessary to use preceding acid gas denuders or nylon filters.

Water-soluble Ca ++ , Mg + , and PO 4 3- are also found in coarse part icles and may be indicative of

sources. Water-soluble Ca +2 is formed by the reaction of ac id gases with calcium carbonate (Krueger et al., 2004).

Ion analysis is important for PM 10-2.5 , but it is unnecessary to allo cate a separate nylon channel for sampling and analysis. If a URG3000N samp ler is used for carbon analysis, a 47 mm quartzfiber filter should be used (w ith an exposed area of 11.8 cm 2 ) to allow for both carbon (0.5 cm 2
punch) and ionic (1/2 of the 47 mm quartz-fib er filter) speciation. Th e current 25 mm filter configuration in the URG 3000N wi th an exposed area of 3.5 cm 2 is not adequate for both carbon and ion speciation, especially if carbonate or other analys es are considered.

3. The 2004 CD included a list of important PM 10-2.5 components which included biological materials and fly ashes. If these species are im portant to characterize, what specific types of biological materials and fly ashes should be incl uded? 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 lo cated near a coal-fired power plant or if there are fly ash storage piles nearby. Mo st modern industrial stacks have particle control devices that remove most of the coarse particles, and fug itive 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 PM 2.5 and PM 10 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 estimat e 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; Ki m, 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 unk nown sources, but automated image recognition methods perform best with low particle densiti es (i.e., low flow rates of 1-2 Lpm) and a consistent background, such as that provided by flat polycarbonate filt ers; this implies a separate filter channel for microscopic analysis.17 17 Bioaerosols, including plant pollen and microorganisms (mol d and bacteria) have been recognized as potential health hazards (e.g., H eederik, 2003; Schulze et al ., 2006; Steerenberg et al., 2003; Targonski et al., 1995), but have not been widely studie d (e.g., Heinrich et al., 2003; Menetrez et al., 2000; 2001; 2007b). If standard operating procedur es (SOPs) can be established and target species dete rmined, a subset of PM 2.5 and PM 10-2.5 samples (e.g., near agricultural fields, livestock, and vacant la nds) should be analyzed for f ungi, endotoxins, and proteins.

5. Can the complication of particle size and abs orption effects in XRF be resolved using absorption correction factors? If not, w hat other method(s) should be considered?

Yes, corrections have been successfully devi sed 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; Rhode s and Hunter, 1972; Sewell et al., 1985; Wagman et al., 1978). Some further work is n eeded 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 w ould 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 en ergetic absorption edges and emitted X-rays. Dzubay and Nelson (1975) show ed that attenuation changes with 10 and 15 μm particles as shown in Figure C. The derived attenuation factor is sh own in Table B (Dzubay and Nelson, 1975) for their XRF set-up.

Figure C. Attenuation factors for K
α 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 K
α X-ray fluorescence of various elements in coarse particles deduced from Fi gure 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 interf erence 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 tran smittance and reflectance corrections (Fung et al., 2004); and 3) catalysts increase the EC oxidati on rate (Lin and Frie dlander, 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 PM 10

and low PM 2.5 good candidate sites for PM 10-2.5 speciation? Given that there will be some urban and rural NCore monitoring sites with PM 10-2.5 speciation, what other factors should be considered in selecti ng the pilot monitoring an d long-term sites or

locations?

Sites with high PM 10 and low PM 2.5 (e.g., Las Vegas, NV, during sp ring; Chow et al., 1999) or19 19 low PM 10 and high PM 2.5 (e.g., wintertime in central Califor nia; Chow et al., 2005) are good candidates to test the high and low PM 10-2.5 mass and composition, respectively. The PM 2.5 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 PM 10-2.5 speciation monitoring requirements during a future rulemaking, should changes to the network design be considered? For example, changing the total number of required m onitors and/or the required locations?

While there is a desire to collocate PM 10 and PM 2.5 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 PM 10-2.5 sites.

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### Mr. Bart Croes

These comments also reflect input from Califor nia Air Resources Board (ARB) staff responsible for implementing U.S. EPA monitoring requirement s and using the data in source apportionment

and health studies.

PM 10-2.5 Speciation Measurement

1. Table 1 provides a list of proposed PM 10-2.5 species and analysis methods. Are there

additional PM 10-2.5 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 dichot omous samplers, MetOne SASS speciation
monitors, PM 10 and PM 2.5 FRMs are potential sampling devices (with the appropriate filter types) for PM 10-2.5 speciation. Among these sampler types, wh ich should be included or excluded from the pilot network design? Are there other sa mpling devices not listed here that should be

considered?

A dichotomous sampler would be a superior choi ce. While California has dismantled its 20-site network that operated from 1983 to 2001 (due to resource constraints once the PM 2.5 FRM network was deployed), the data ar e in reasonable agreement for PM 2.5 and PM 10 (Motallebi, et al., 2003a) which has allowed us to determine long- term PM trends (Mota llebi, et al., 2003b) and perform particle pollution assessments in areas of California that exceed state and federal ambient air quality standards (M otallebi, 1999; Motallebi and Dolis lager, 1999; Motallebi, et al., 2003bc).

I understand the concerns expressed by Delb ert 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- μ m cut point for ions and metals, add a 10- μ m 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 th at 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 implemen t 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 PM 2.5 . To implement the carbon speciation by difference would require a second URG with a 10- μ m cut point.

3. What are the PM 10-2.5 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 PM 10-2.5 speciation and if so what specifi c issues make it problematic?32 32 Any potential artifact s would be consistent with the PM 2.5 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

PM 10-2.5 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 PM 10-2.5 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 co nfirms there is sufficient mass for trace metal speciation (Motalle bi, et al., 2003a).

PM 10-2.5 Species or Components

1. Table 1 provides a list of proposed PM 10-2.5 species and analysis methods. Among these species, which are most important? Are ther e 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 cr oss check of sulfate ion by IC).

2. In the consideration of poten tial ion measurements for PM 10-2.5 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 PM 10-2.5 ?

Nitrate and ammonium are always important. At least in Los Angeles, coarse particle nitrate appears to be significant, but it is usua lly in the form of sodium nitrate.

3. The 2004 CD included a list of important PM 10-2.5 components which included biological materials and fly ashes. If these species are im portant to characterize, what specific types of biological materials and fly ashes should be incl uded? 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 abs orption effects in XRF be resolved using absorption correction factors? If not, w hat other method(s) should be considered?

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

there is no consensus on their us e. In California, we do not use any correction factors for PM 2.5 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 interf erence in thermal-optical analysis (TOA) of

PM 10-2.5 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 PM 10

and low PM 2.5 good candidate sites for PM 10-2.5 speciation? Given that there will be some urban and rural NCore monitoring sites with PM 10-2.5 speciation, what other factors should be consider ed in selecting the pilot mon itoring and long-term sites or

locations?

Sites with high PM 10 and low PM 2.5 suggest areas dominated by wind blown dust. If the source is obvious for a particular site, I question the value (and diversion of resources) fo r investigating an air quality issue that may already be well und erstood. Because of higher deposition rates for coarse particles, a PM 10-2.5 monitoring site is representative of sources relatively nearby, so it should be obvious if a single s ource (e.g., windblown dust, coal pi le, tire and brake wear) is predominant.

The pilot monitoring study should include a southern California site that is high in both PM 10 and

PM 2.5 with potential for significant coarse particle contributions from sources other than windblown dust, such as coarse particle nitrate. Ot her sites for pilot studies and long-term monitoring

can be selected based on an analysis of existing PM 10 and PM 2.5 network data to identify areas (using the difference method) that are high in both PM 10-2.5 and PM 2.5

.

2. If there is an opportunity to modify the NCore PM 10-2.5 speciation monitoring requirements during a future rulemaking, should changes to th e network design be considered? For example, changing the total number of required monitors and/or the required locations?

The Health Effects Institute or other repr esentations of the ai r pollution epidemiology community should be consulted as to where year-round PM-coarse measurements would be useful for epidemiologic cohort studies. Otherwis e, I agree with USEPA staff that the candidate NCore site may not be the best choice for PM 10-2.5 speciation since the highe st concentrations of

PM 2.5 and PM 10-2.5 are usually not collocated. A study by ARB staff (VanCuren, 1999) concludes34 34 that, in winter, most coarse (PM10-2.5) partic les 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 influe nced by regional emissions. The implications for interpretation of sample anal yses are as follows: (1) Typical PM sampling networks are unlikely to represen t regional conditions; (2) Similarity of samples in time and space between widely separated samplers pr obably arises from sampling analogous local environments rather than a uniformly mixed regi onal 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 misapplic ation 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 part icles will skew source apportionment by chemical

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

VanCuren, T. (1999) Spatial Factors Influenc ing Winter Primary Pa rticle Sampling and Interpretation. J. Air Waste Manage. Assoc.

, 49: PM-3-15.

Motallebi, N. (1999) Wintertime PM 2.5 and PM 10 Source Apportionment at Sacramento,

California. J. Air Waste Manage. Assoc.

, 49: PM-25-34.

Motallebi, N. and L. J. Dolislager (1999) Charac terization 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 – Inte rcomparison of several PM 2.5 , PM 10-25 , and PM 10 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 PM 2.5 , PM 10-25 , and PM 10

. 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 sel ected sites in California. J. Air Waste Manage. Assoc.

, 53:

867-888.35 35 

### Dr. Kenneth Demerjian

PM 10-2.5 Speciation Measurement

1. Table 1 provides a list of proposed PM 10-2.5 species and analysis methods. Are there

additional PM 10-2.5 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 dichot omous samplers, MetOne SASS speciation
monitors, PM 10 and PM 2.5 FRMs are potential sampling devices (with the appropriate filter types) for PM 10-2.5 speciation. Among these sampler types, wh ich should be included or excluded from the pilot network design? Are there other sa mpling devices not listed here that should be

considered?

Run two (2) EC – OC semi-continuous (hourly average) measurements outfitted with PM 10 and

PM 2.5 inlets respectively. Although th is 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 PM 10-2.5 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 PM 10-2.5 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 PM 2.5 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

PM 10-2.5 mass or the dichotomous sampler (16.7 Lpm). If this sampler was configured for PM 10-

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 PM 10-2.5 FRM?

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

to PM 10-2.5 , but why speculate, perform th e 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 cl osed. If not, you will need to consider other options.36 36 PM 10-2.5 Species or Components

1. Table 1 provides a list of proposed PM 10-2.5 species and analysis methods. Among these species, which are most impor tant? Are there important PM 10-2.5 species or components missing from this list? Are there important analysis methods missing from this list?

The compiled list is reasonable for the ma jority of contributing sources to PM 10-2.5 . There is always the possibility of a unique PM coarse source whose chemical composition is not on this list and would require the a pplication of species speci fic analytical technique.

2. In the consideration of poten tial ion measurements for PM 10-2.5 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 PM 10-2.5 ?

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 PM 10-2.5 components which included biological materials and fly ashes. If these species are im portant to characterize, what specific types of biological materials and fly ashes should be incl uded? 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 pot ential utility in this application.

4. Can the complication of particle size and abs orption effects in XRF be resolved using absorption correction factors? If not, w hat other method(s) should be considered?

Absorption correction factors are likely to be variable and on ly reproducible in controlled environments. Consider the application of ICP/MS analytical technique.

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

PM 10-2.5 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 invest ment of resources to study the phenomena in the laboratory and the field.

Network Design

1. Are sites with high PM 10

and low PM 2.5 good candidate sites for PM 10-2.5 speciation?37 37 Given that there will be some urban and rural NCore monitoring sites with PM 10-2.5 speciation, what other factors should be considered in se lecting the pilot monitori ng and long-term sites or

locations?

The majority (if not all) of urban NCore mon itoring sites are not depl oyed in locations to adequately sample PM 10-2.5 exposures. The likely source regions impacting PM 10-2.5 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 PM 10-2.5 speciation monitoring requirements during a future rulemaking, should changes to th e network design be considered? For example, changing the total number of required monitors and/or the required locations?

The design criteria for loca ting urban NCore level 2 monito ring sites must consider measurements in neighborhoods in proximity (e .g. within 500m) of signi ficant traffic sources (major highways). Estimates of population with 500m of major roadways within metropolitan areas is one metric for determining the distributi on of traffic impacted vs. central urban monitors to be deployed. One in three urban monitors de ployed to characterize e xposures within traffic impacted neighborhoods would be a reasonable starting point.38 38 

### Dr. Delbert J. Eatough

I. General comments :

The speciation of coarse part icles 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 PM 10-2.5 (coarse) particle fraction of PM 10 , even though a NAAQS for coarse particles has not been set by the agency. I encour age 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 b een necessarily tied to the PM 2.5 sampling FRM because of the requirement to understand the speciation of PM 2.5 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, th e 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 hea lth effects related to fine partic les 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. Ther efore, I recommend that EPA include important aspects of improved PM monitoring methods in th e coarse particle speciation program to allow for a better tie of all components to any obser ved health effects exacerbated by exposure to coarse particles.

While many components of coarse particle s will be unaffected by the sampling protocols used, this is not true for all components. Th e 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 sampli ng 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 understoo d. Inattention to sampling artifacts in the program will bias the results towards those co mponents which are not affected by the sampling

method. There are at least two ar eas where the sampling methods us ed will significantly affect

the obtained outcome.

In the review of these two areas in the mate rial to follow, I have focused mainly on our past work. I have done this because of the shor t 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 coar se 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 elemen tal carbon are major components of these fine particles. If the aerosol is acidi c, 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 debr is, etc. Sulfate concentrations are generally very low. Nitrate can be present in these fine particles, but is ge nerally 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) + HNO 3 (g) → NaNO 3 (s) + HCl(g)

When fine and coarse particles are collected toge ther reactions can occur in the collected mixture because of the introduction of dissimilar compositi ons. The best documented of these changes is the loss of coarse particulate ni trate 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),

NaNO 3 (s) + HN 4 HSO 4 (s) → NaHN 4 SO 4 (s) + HNO 3 (g)

and similar reactions. In addition, changes in coar se particulate organic ma terial can be expected to occur from reaction with fine particulate re active 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 a nd coarse particles are collected and analyzed separately. This argues for the use of a dicot sa mpler or similar device. The EPA heard several strong pleas fore use of dichot samplers and the avoidance of FM integrated PM 10 filter collected sample (for use in a differential speciation calcula tion) in the coarse particle speciation network. I add my strong vote to those views for the addi tional 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 (PM 2.5 , particles with an aerodynamic diameter less

than 2.5 μ m) has been implicated as a contributor to adverse human health effects including increases in cardiovascular and pulmonary diseas e which leads to elevated human mortality and morbidity (Pope and Dockery, 2007). The role coarse particulate matter (PM 10-2.5 ) may play in exacerbating health problems is not as well understood. PM 2.5 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 (i ncluding 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 include s ammonium nitrate (Finlayson-Pitts and Pitts, 2004) and low molecular weight orga nic species (e.g., SVM that exis ts in the atmosphere in the40 40 particle phase can be lost from particles during sampling making it difficult to measure, Eatough et al., 2003). The composition of coarse part icles 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 concentrat ions (Eatough et al., 2003). These techniques could be applied to the chemical characterization of coarse part icles. Although these samplers can accurately speciate PM 2.5 , including SVM, there are severa l drawbacks to their use. Integrated samplers are very labor and cost in tensive. Collection of filter media and in-lab analysis are time consuming and co st 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 PM 2.5 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 PM 2.5 mass because the particle collection fi lter is heated to 30-50°C to re move particle bound water, which also results in loss of SVM. The Rupprecht & Patashnick Filter Dynamic Measuring System (FDMS, Meyer et al., 2002), and GRIMM mon itors (Grimm and Eatough, 2009) have been developed to measure total PM 2.5 mass, including SVM. The GRIMM monitor will measure

both PM 2.5 and PM 10-2.5 . A dicot based FDMS has now been released by Thermo, and is in use at some state monitoring sites, which will also measure both PM 2.5 and PM 10-2.5. Real-time instruments have several advantag es including, reliability, cost e ffectiveness, ease of sampling and reduction in labor requirement s. One prominent advantage of real-time instruments is the ability to temporally resolve short term episodes of PM 2.5 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 un certainty) of source apportionment techniques to determine sources, both primary and sec ondary, of urban PM (Grover and Eatough, 2008; Eatough et al., 2008a).

Both the FDMS TEOM and GRIMM Technolog ies Inc. (Model 1.180) optical particle monitor have Nafion dryers at the inle t to remove particulate water. PM 2.5 measurements with these two instruments were comp ared during the winter of 2007 in Lindon, Utah. The excellent agreement between these two inst ruments (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 I M M , μ g / m 3

41 0 20 40 60 80 100 120

FDMS TEOM, μg/m 3 y = (0.995±0.007)x + 3.0±5.0 μg/m 3

N = 567, R 2 = 0.97
Sigma = 4.0 μg/m 3 (±9.6%) Figure 1. Comparison of

PM 2.5 hourly average massmeasurements 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 PM 2.5 mass with an R&P FDMS TEOM and 1-h measurement of fine particulate co mponents, including the semi-volatile nitrate and organic material in Rivers ide, California have also shown excellent agreement (Figure 2, from Grover et al., 2008b), indicating the semi-vol atile material is well measured by the FDMS TEOM. In This study, the SVM averaged 36% of the total PM 2.5 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

μ g / m 3 FDMS SUM

0 2 0 4 0 6 0 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, NH 4 NO 3 and

ammonium sulfate.

0 0 20 40 60 80

C o n s t r u c t e d M a s s ( μ g / m 3 )The above referenced studies indicate that PM 2.5 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 a llow similar comparisons to be made for PM 10-

2.5

.

A measure of the amount of semi-volatile mate rial in both fine and coarse particles can also be using the conve ntional TEOM (30 or 50 Ε C), coupled with FDMS TEOM and GRIMM

monitor data. This is illustra ted by results obtained during th e study in Lindon (Hansen et al., 2009). Concentrations of PM 2.5 mass were made with a conventional TEOM, and FDMS TEOM

and the GRIMM monitor. PM 10 was measured with a conv entional TEOM and the GRIMM

monitor. The conventional TEOM does not measur e 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 PM 2.5 and PM 10 SVM concentrations obtained from the FDMS TEOM, GRIMM and conventional TEOM monitor data are compared in Fi gure 3 (from Hansen et al., 2009). Included in Figure 3 are error

bars indicated the estimated uncerta inty in the comparison. As indica ted, 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 PM 10 . This indicates the presence of se mi-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 re sults shown in Figure 3 are consistent with these expectations based on atmospheric formation processes. However, a sm all, but significant amount of semi-volatile material is present in th e coarse particles. Ch emical analysis of 24-h integrated filter samples confirmed that little nitrate was present in the coarse particles, suggesting the coarse particulate se mi-volatile material is organic.

42 60

0 10 20 30 40 50 60 

### SVM, PM 2.5 

### , μg/m 3 0 10 20 30 40 50

S V M , P M 1 0 , μ g / m 3 Figure 3. Comparison of the

calculated concentrations of

PM 2.5 and PM 10 semi-volatile material at Lindon UT, see

text.Comparisons such as those shown here shoul d be obtained in the EPA coarse speciation monitoring program to determine if semi-volatile ma terial is important in coarse particles in a variety of urban areas. This will in turn, indi cate if conventional filter pack sampling can be expected to give an accurate pi cture of total coarse particle ma ss 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 car bonaceous material) can help elucidate the

sources of the semi-volatile material. This will he lp 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.

PM 10-2.5 Speciation Measurement

1. Table 1provides a list of proposed PM 10-2.5 species and analysis methods. Are there

additional PM 10-2.5 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 PM 10-2.5 composition and mass when fine and coarse particles are mixed during sampling (see above di scussion), all analyses should be done on a

PM 10-2.5 discrete sample and not inferred by a PM 10 - PM 2.5 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-volat ile 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 PM 10-2.5 mass using a conventio nal 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 PM 10-2.5 basis and not inferred from differen ce 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 signifi cant semi-volatile material is pr esent 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-volat ile organic material). For the reasons outlined above, it is important that all these measurements be done on a PM 10-2.5 collected sample and not determined by difference.

Fly Ash. We have done extensive work on the anal ysis of fly ash in collect PM (e.g. Eatough et al., 2000). SEM analysis is only practicable on Poly carbonate filters. If the data are intended to be use in source apportionment, a PM 10 sample should be analyzed. We found it best to pre-treat the sample with an acid wash and firing before an alysis to optimize detec tion of insoluble fly ash particles.2. Various sampling devices, including dic hotomous samplers, MetOne SASS speciation
monitors, PM 10 and PM 2.5 FRMs are potential sampling devices (with the appropriate filter types) for PM 10-2.5 speciation. Among these sampler types, wh ich should be included or excluded from the pilot network design? Are there other sa mpling 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 equiva lent device to provide a discrete PM 10-2.5 sample).

This would rule out the use of PM 10 FRM samplers.

3. What are the PM 10-2.5 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 PM 10-2.5 speciation and if so what specif ic issues make it problematic?

Speciation by the difference method is problema tical. Details on artifacts and the approach which should be taken in speciation are discussed in detail above.

4. The current and most widely used PM 2.5 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

PM 10-2.5 mass or the dichotomous sampler (16.7 Lpm). If this sampler was configured for PM 10-

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 PM 10-2.5 FRM?

It has been my experience, base d on extensive work with diffusi on denuder samplers, that in a 24-h sample the results obtained are largely inde pendent of flow rate. This is because the kinetics for changes which occur during sampling ar e 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 PM 2.5 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

PM 10-2.5 mass or the dichotomous sampler (16.7 Lpm). If this sampler was configured for PM 10-

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 PM 10-2.5 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.

PM 10-2.5 Species or Components

1. Table 1 provides a list of proposed PM 10-2.5 species and analysis methods. Among these species, which are most impor tant? Are there important PM 10-2.5 species or components missing from this list? Are there important an alysis methods missing from this list?

If your goal is characterization fo r source apportionment and health effect etiol ogy 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.

442. In the consideration of pot ential ion measurements for PM 10-2.5 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 PM 10-2.5 ?

Nitrate is expected to be present mainly as the sodium salt. Bu t knowing both nitrate and ammonium ion would be valuable. If, as we su spect, 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 collecti on is advised. Do you have any da ta on the transfer of coarse particles through an annular denuder?

3. The 2004 CD included a list of important PM 10-2.5 components which included biological materials and fly ashes. If these species are im portant to characterize, what specific types of biological materials and fly ashes should be incl uded? 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 fam iliar with monitoring for biological materials.

4. Can the complication of particle size and abs orption effects in XRF be resolved using absorption correction factors? If not, w hat other method(s) should be considered?

I will leave this to those who know.

5. Are metal oxides a significant source of inte rference in thermal-optic al analysis (TOA) of

PM 10-2.5 for OC and EC given the large expected soil component? If so, how should this interference be addressed?

This is certainly a potential in terference 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 PM 10

and low PM 2.5 good candidate sites for PM 10-2.5 speciation? Given that there will be some urban and rural NCore monitoring sites with PM 10-2.5 speciation, what other factors should be consider ed in selecting the pilot mon itoring and long-term sites or

locations?

This question seems to imply the use of differen ce methods. I have outlined why this is not a good idea above.

452. If there is an opportunity to modify the NCore PM 10-2.5 speciation monitoring requirements during a future rulemaking, should changes to th e 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 PM 10-2.5 mass and components as well as give di urnal data which would be very helpful in understanding the effects of changing mete orology, 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) Usin g 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: Meeti ng a Measurement Ch allenge (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 a nd sulfate at the Grand Canyon during the Project MOHAVE Summer Intensive, J. Air & Waste Mana gement Association 50 , 759-

774.

Eatough D.J. and Ellis E.C. (1983) A Comparis on 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) Fo rmation 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 Meas urement: The Use of Op tical Light Scattering

for the Determination of Particulate Size Di stribution, and Particulate Mass, Including the Semi-Volatile Fraction; J. Air Waste Manage. Assoc. 59, 101-107.

Grover, B.D. and Eatough, D.J. (2008a) Sour ce Apportionment of One-Hour Semi-Continuous Data using Positive Matrix Factorizati on 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 Co mponents of Fine Part iculate Matter in

46Riverside, 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 PM 2.5 and PM 10 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 Mo nitor for Ambient Air; paper presented at the Symposium on Air Quality Measuremen t Methods and Technology, San Francisco, CA, November.

Patashnick, H.; Rupprecht, E.G. Continuous PM 10 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 Pa rticulate Matter. Repor t No. EPA/600/P-99/002aF, Environmental Protection Agenc y, Research Triangle Park, NC.

47

### Mr. Dirk Felton

PM 10-2.5 Speciation Measurement

1. Table 1 provides a list of proposed PM 10-2.5 species and analysis methods. Are there

additional PM 10-2.5 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 performi ng detailed OC component and molecular marker analysis on some of the filter samples.

2. Various sampling devices, including dic hotomous samplers, MetOne SASS speciation
monitors, PM 10 and PM 2.5 FRMs are potential sampling devices (with the appropriate filter types) for PM 10-2.5 speciation. Among these sampler types, wh ich should be included or excluded from the pilot network design? Are there other sa mpling devices not listed here that should be

considered?

The SASS PM-10 inlet is not yet viable and th e SASS may not have enough sample volume for some PMc components in some areas of the count ry. There are many existing Cascade Impactor designs and it is possible that one of those c ould 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 spectrometr y. 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 PM 10-2.5 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 PM 10-2.5 speciation and if so what specif ic 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 volatilizat ion are likely to occur preferentially for one component size fraction (PM-10, PM-2.5) or the ot her 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 concentr ation is less attractive for component analysis

because it is not known if the corre ction or the presence of fine particles on the coarse mode filter will preferentia lly affect one component over another.

4. The current and most widely used PM 2.5 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

PM 10-2.5 mass or the dichotomous sampler (16.7 Lpm). If this sampler was configured for PM 10-

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 PM 10-2.5 FRM?

48In 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 sa mpler would have loadings of 104 ug and 192 ug respectively. These lower loadi ngs certainly increase the signi ficance 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 perf ormed by ThermoFisher Scientific, Franklin, MA, the vendor was required to run filter ba sed low volume FRM PM-2.5 and PM-10 samplers in triplicate. The average standard deviat ion of the three calcula ted 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 issu e 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 surpri sing considering the low PMc concentrations and the issue of large particle retention on filters prior to gravimetric analysis. The amount of mass shoul d 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.

PM 10-2.5 Species or Components

1. Table 1 provides a list of proposed PM 10-2.5 species and analysis methods. Among these species, which are most impor tant? Are there important PM 10-2.5 species or components missing from this list? Are there important an alysis 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 ar eas. The New York State Department of Environmental Conservation (NYSDEC) undert ook a pilot study for PMc speciation by

difference. Low volume PM-2.5 and PM-10 FRM sa mplers were installed in New York City and in Niagara Falls. The samplers were operate d 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 fi ne and coarse mode. Arsenic wa s unique in that it appears to

have a distinct source in bot h fine and coarse modes.

49The concentrations of the elemental data for al l 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 Ceug/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 iden tified and are likely to be corr elated 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 pilo t should establish a few s ites 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 co mponents collected in the pilot.

502. In the consideration of poten tial ion measurements for PM 10-2.5 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 PM 10-2.5 ?

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 PM 10-2.5 components which included biological materials and fly ashes. If these species are im portant to characterize, what specific types of biological materials and fly ashes should be incl uded? 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 consid er evaluating concentration di fferences in results between samples collected with PMc samplers and sample rs 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 incl uded 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 abs orption effects in XRF be resolved using absorption correction factors? If not, w hat other method(s) should be considered?

The XRF analysis for the more h eavily loaded PM-10 filters is modified by extending the count time for the detector. Extending the count time may or may not elim inate the uncertainty associated with an increase in X-Ray absorp tion. The EPA should spons or experimentation by loading filters with different component mixes of PMc and then compare the XRF results with ICPMS digestive analysis.

515. Are metal oxides a significant source of inte rference in thermal-optical analysis (TOA) of

PM 10-2.5 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 PM 10

and low PM 2.5 good candidate sites for PM 10-2.5 speciation? Given that there will be some urban and rural NCore monitoring sites with PM 10-2.5 speciation, what other factors should be consider ed in selecting the pilot mon itoring 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. NC ore 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 s hould be designed to help ascertain the highest concentrations of PMc components likely to be associated with h ealth effects. This strategy will accelerate the linking of health effects and indivi dual PMc component concentrations

2. If there is an opportunity to modify the NCore PM 10-2.5 speciation monitoring requirements during a future rulemaking, should changes to th e 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 effo rts in the rest of the network.

Health researchers are continually stressing a pref erence for daily data due to lag structure in health effects studies and the PMc pilot should be designed to the extent po ssible to provide daily

or continuous data.

52

### Dr. Philip Hopke

PM 10-2.5 Speciation Measurement

1. Table 1 provides a list of proposed PM 10-2.5 species and analysis methods. Are there

additional PM 10-2.5 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 unfort unately is still being put forth as the standard approach? I suggest that the ke y is less on the analytical method as on the sampling approach.

2. Various sampling devices, including dic hotomous samplers, MetOne SASS speciation
monitors, PM 10 and PM 2.5 FRMs are potential sampling devices (with the appropriate filter types) for PM 10-2.5 speciation. Among these sampler types, wh ich should be included or excluded from the pilot network design? Are there other sa mpling devices not listed here that should be

considered?

I strongly recommend against usi ng the difference method. There is the potential for substantial interactions between the fine and coarse partic les on the PM10 filter. For example, fine NH4NO3 can dissociate to produce HNO3 that would react w ith alkaline coarse part icles. 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 impact or system to collect specific coarse particle samples where there would be l ittle supercoarse or fine part icle contamination. Such an impactor would have two stages. The first woul d 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 availabl e), it makes sense to go with the dichot.

3. What are the PM 10-2.5 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 PM 10-2.5 speciation and if so what specif ic 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 impacti on system that would still intermix so me fine particles into the coarse particle sample.

534. The current and most widely used PM 2.5 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

PM 10-2.5 mass or the dichotomous sampler (16.7 Lpm). If this sampler was configured for PM 10-

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 PM 10-2.5 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 w ould provide sufficiently large samples to ensure good analytical precision. I have provided a presentation outlining such a system that is ready for testing.

PM 10-2.5 Species or Components

1. Table 1 provides a list of proposed PM 10-2.5 species and analysis methods. Among these species, which are most impor tant? Are there important PM 10-2.5 species or components missing from this list? Are there important an alysis methods missing from this list?

We know a lot less about the coarse fraction and wh at are critical species pa rticularly for primary biological species that are going to be more prevalent in coarse fraction samples compared to fine particle samples. Protei n alone is highly unlikely to pr ovide a reliable estimate of total biological particulate mass.

Are there sufficient resources available to perform CCSEM on e nough filters for enough particles to provide statistically va lid numbers of particles to adequa te quantify the particle types. Are they envisioning automated analysis of th e data? Will they collect secondary electron images as well as backscatter images and x-ra y spectra? One can envision automated image analysis software that could so rt the particles into various ma jor categories, but there is no discussion of how the analyses are to be conduc ted. Manual SEM and review of images will not be sufficient to provide support to a national network of samplers.

2. In the consideration of poten tial ion measurements for PM 10-2.5 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 PM 10-2.5 ?

Nitrate is important for the coarse sample as well as fine although the coar se particle nitrate is generally present because of the reaction of gaseous HNO3 with th e alkaline coarse particles. This problem also supports the need for using devi ces that separate coarse and fine fractions and not using the difference method.

543. The 2004 CD included a list of important PM 10-2.5 components which included biological materials and fly ashes. If these species are im portant to characterize, what specific types of biological materials and fly ashes should be incl uded? 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 tota l protein assay would suffice to provide an index of total biological material. It may be more us eful to look at specific species such as endotoxin or specific aeroallergens. Th ere are now easy to use kits at reasonable prices to perform ELIZA analyses. It is likely that a dditional species tests coul d be developed for other identified allergens.

4. Can the complication of particle size and abs orption effects in XRF be resolved using absorption correction factors? If not, w hat 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 narr ower range of particle sizes in just a coarse particle sample. Also the differences in composition from location to

location also need to be consider ed as it is the combination of particle compositi on and size that affect the penetrability of the fluoresced x-ray.

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

PM 10-2.5 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 re lative 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 PM 10

and low PM 2.5 good candidate sites for PM 10-2.5 speciation? Given that there will be some urban and rural NCore monitoring sites with PM 10-2.5 speciation, what other factors should be consider ed in selecting the pilot mon itoring 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 issu e 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 valu e of the sites available.

552. If there is an opportunity to modify the NCore PM 10-2.5 speciation monitoring requirements during a future rulemaking, should changes to th e 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 ve ry 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 flex ibility in the network design. That was part of the NCore philosophy.

56Multi-Filter Coarse Particle ChemicalSpeciation Sampler Using VirtualObjective:Develop a Coarse Particle ChemicalSpeciation Sampler to Obtain FilterSamplers Similar to the Current Fine ParticleChemical Speciation Sampler Used InEPA’s Fine Particle Monitoring Network withthe Goal of Obtaining a Nearly CompleteMass Balance on the Collected Coarse PMDesign•Premise–Need to Separate Fine and Coarse Particles for All the Usual Reason•Better Understand Health Effects of PMc vs PMf•Source Apportionment•Not Mixing Fine and Coarse Chemistry (fine acidic, coarse basic)–Obtain Separation with a Virtual Impactor–Design Around the Current PMc and PMf FRM Flow Rates (16.7 LPM),Option for 6.7 LPM to Match the Current MetOne PMf SpeciationSampler–Include Design Flexibility for Additional Measurements•Flexibility–Allows Multiple Filters, Denuders, Back Up Filters as Needed toMinimize Interferences–Bypass Allows for Large Samples to Be Collected for ToxicologicalTesting, Organic Speciation, Trace and Ultra-Trace Metals Speciation,Including Valance States–Virtual Impactor Can Have 5% Coarse, 95% Fine to Minimize GasPhase Artifacts on Coarse Filter*CoarseParticlesFineParticles1000 LPMFlow Splitters16.7 LPM, 47 mm Filters49.1 LPM, 90 mm Filter bypass flow833 LPM, 203 mnm X 250 mm Filterbypass flowExisting CommercialHigh Volume Fine andCoarse Sampler Basedon Virtual ImpactionVirtual Impactor90% Fine, 10% Coarse*Modified Sampler for PMc Chemical SpeciationGeneral SchematicDesign and Evaluation by ClarksonUniversity and U.S. EPS UnderwayCurrently.Commercialization by GreentechEnvironmental. AvailablePrototype for OAQPS Testing, May15, 2009

### Dr. Rudolf Husar

PM 10-2.5 Species or Components

1. Table 1 provides a list of proposed PM 10-2.5 species and analysis methods. Among these species, which are most impor tant? Are there important PM 10-2.5 species or components missing from this list? Are there important an alysis methods missing from this list?

No

2. In the consideration of poten tial ion measurements for PM 10-2.5 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 PM 10-2.5 ?

Nitrate is important

3. The 2004 CD included a list of important PM 10-2.5 components which included biological materials and fly ashes. If these species are im portant to characterize, what specific types of biological materials and fly ashes should be incl uded? 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 abs orption effects in XRF be resolved using absorption correction factors? If not, w hat other method(s) should be considered?

Saturation is real. Keep deposition density low?

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

PM 10-2.5 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 PM 10-2.5 speciation measurement and on PM 10-2.5 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 netw ork 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 PM 10-2.5 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 di stributions, sources, and h ealth 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 c onfidence 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 PM 10-2.5. It is possible that organic carbon speciation would help resolve some of these sources. While th is 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 sp ecies is able to resolve carbon sources satisfactorily. This should include source sampling for the PM 10-2.5 fraction as well, although that’s not necessarily a network function. Continuous sampling for PM 10-2.5 mass and components (at least EC/OC) would certainly be helpful as well.

Network design

1. Are sites with high PM 10 and low PM 2.5 good candidate sites for PM 10-2.5 speciation? Given that there will be some urban and rural NCore monitoring sites with PM 10-2.5 speciation, what other factors should be considered in selecting the pilot monito ring and long-term sites or locations?

One should aim for a selection of sites that represent varying ratios of PM 10 :PM 2.5 , 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 wilderne ss areas but agricultural areas al so), and various meteorological regimes. It seems like most of the NCore site s as currently proposed are generally populationoriented PM2.5 sites. Sites that re flect maximum and representative PM 10-2.5 exposures will not necessarily coincide with those PM2.5 sites, so the pilot program should ha ve the flexibility to

monitor at locations outside the NCore network. Based on data co llected in the next few years,

informed decisions could then be made about long-term sites.

612. If there is an opportunity to modify the NCore PM 10-2.5 speciation monitoring requirements during a future rulemaking, should changes to the network d esign be considered? For example, changing the total number of required monitors and/or the required locations?

Of course changes to the network should be c ontinually under consideration; hopefully that’s an important objective of a pilot network. Lear n what works and what doesn’t and adjust accordingly. As noted above, it seems much t oo 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 mu ch better investment of our scarce monitoring dollars than a hasty move to monitor at all 75 NC ore sites. Let the research community evaluate these results, come to agreement on speciation sampling and analysis pr otocols, then move

forward with a broader networ k that’s truly science-based.

62

### Dr. Thomas Lumley

PM 10-2.5 Species or Components

1. Table 1 provides a list of proposed PM 10-2.5 species and analysis methods. Among these species, which are most impor tant? Are there important PM 10-2.5 species or components missing from this list? Are there important analysis methods missing from this list?

Distinguishing burning biomass (w ood or grass) from other car bon sources with levoglucosan may be useful and relatively inexpensive.

2. In the consideration of poten tial ion measurements for PM 10-2.5 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 PM 10-2.5 ?

Not my field.

3. The 2004 CD included a list of important PM 10-2.5 components which included biological materials and fly ashes. If these species are im portant 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 sm oke is important to di stinguish as there are straightforward ways to reduce emission. Specifi c allergenic pollen sources may be important when studying health effect s of the coarse fraction.

4. Can the complication of particle size and abs orption effects in XRF be resolved using absorption correction factors? If not, w hat other method(s) should be considered?

Not my field

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

PM 10-2.5 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 PM 10

and low PM 2.5 good candidate sites for PM 10-2.5 speciation? Given that there will be some urban and rural NCore monitoring sites with PM 10-2.5 speciation, what other factors should be considered in selecting the pilot mon itoring and long-term sites

or locations?

63Speciation will be relati vely straightforward, especially by the difference method, in sites with high PM10 and low PM2.5. The sources and species contributing to the co arse 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 ra ther 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 PM 10-2.5 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 site s whose coarse-fraction composition is likely to be different from those already in the network, esp ecially if large numbers of pe ople may be exposed. While it is

true that local sources have a la rger contribution to coarse PM th an 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 hea lth effects of coarse PM. Monitoring in areas with low population density may be informative about sour ces but is unlikely to be useful for studying

health effects.

64

### Dr. Peter H. McMurry

PM 10-2.5 Speciation Measurement

1. Table 1 provides a list of proposed PM 10-2.5 species and analysis methods. Are there

additional PM 10-2.5 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 unde rstood 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 s easonal variation.” While the carbon content of biological material ought to be detected by OC/EC an alyses, 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 c oncentration 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 f og,” suggesting that fog droplets act as culture media for biologi cal particles. Mohler et al . {, 2007 #21265} report that biological particles may play an important role in cloud formation. Given the pot ential significance of biological particles in coarse particles, an effort should be made to quantify their contribution to mass. I am not sufficiently knowledgeable to provi de useful input regardi ng suitable analytical

methods.

I agree with the concern expressed by severa l Committee members that OM/OC may be quite different for particles of biological origin, sec ondary OC, and primary. An effort must be mede to determine those ratios for biological particles.

2. Various sampling devices, including dic hotomous samplers, MetOne SASS speciation
monitors, PM 10 and PM 2.5 FRMs are potential sampling devices (with the appropriate filter types) for PM 10-2.5 speciation. Among these sampler types, wh ich should be included or excluded from the pilot network design? Are there other sa mpling devices not listed here that should be

considered?

I would not favor the use of i ndirect methods such as the GRIMM optical detector. The correlations between GRIMM mass and gravim etric mass shown by Delbert Eatough in his remarks are extremely impressive. However, a ssumptions about shape, density, and refractive index must be made to convert optical signal s to mass. In my expe rience, those aerosol properties vary with sampling time and locatio n and will inevitably introduce uncertainties.

I agree with Delbert Ea tough’s comments that chemical intera ctions between fine and coarse particles could affect speciation measurements. This argues against us ing 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 “t ruth” or “agreement” better? I am inclined to agree with Prof. Eatough: If a dichotomous sample r produces results that ar e more nearly “true,”

65then it would be a preferable sampler.

During our conference call Warren Wh ite pointed out another reason to inertially separate coarse and fine particles before collecti on. 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 car riers 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 PM 10-2.5 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 PM 10-2.5 speciation and if so what specif ic issues make it problematic?

Volatilization and chemical reactions due to inter actions of basic and acidic particles; inaccurate

determination of the fraction of collected mass that is water.

4. The current and most widely used PM 2.5 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

PM 10-2.5 mass or the dichotomous sampler (16.7 Lpm). If this sampler was configured for PM 10-

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 PM 10-2.5 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 o ffer the advantage that coarse and fine particles

are not combined to the same ex tent as occurs on the FRM.

PM 10-2.5 Species or Components

1. Table 1 provides a list of proposed PM 10-2.5 species and analysis methods. Among these species, which are most impor tant? Are there important PM 10-2.5 species or components missing from this list? Are there important an alysis methods missing from this list?

I feel that highlighting coarse particles of biologi cal origin is appropriate. I am not an expert on biological particles or on ways to detect them. Eric Edgerton ha s worked on this topic and made some interesting recommendations for chemical a ssays that might provide further information on biological particles.

The document also suggested that SEM might be us ed for biological particles. Indeed, visual observations can provide useful insights into poss ible origins of particle s. However, I am not familiar with automated SEM techniques that have proven reliable for providing the type of

66quantitative information that might be expected fo r 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 poten tial ion measurements for PM 10-2.5 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 PM 10-2.5 ?

George Allen’s admonition that coar se particles are different from fine particles is important. As Bart Croes points out, nitrates (e specially sodium nitrate) can be a significant coarse particle component, especially near the co ast. Judy Chow’s point that ma gnesium can be a useful tracer for agricultural activities is also persuasive.

3. The 2004 CD included a list of important PM 10-2.5 components which included biological materials and fly ashes. If these species are im portant to characterize, what specific types of biological materials and fly ashes should be incl uded? 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 fl y ash as a source categ ory. My other thoughts pertinent to this question are given above.

4. Can the complication of particle size and abs orption effects in XRF be resolved using absorption correction factors? If not, w hat other method(s) should be considered?

I defer.

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

PM 10-2.5 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 PM 10

and low PM 2.5 good candidate sites for PM 10-2.5 speciation? Given that there will be some urban and rural NCore monitoring sites with PM 10-2.5 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.

672. If there is an opportunity to modify the NCore PM 10-2.5 speciation monitoring requirements during a future rulemaking, should changes to th e 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 PM 10-2.5 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 speciati on analysis. Possibly it will be more efficient to include some relatively basic “screening” sampli ng at most coarse specia tion sites , with more detailed analyses at selected sites and/or ba sed on the screening anal ysis. I wonder how much useful information will really be provided by re peating the same TOR & TOT analyses (with the exact same thermal cut-points) for OC & EC? Some molecular level car bon analysis could be revealing at a few sites. A meas urement of light absorption from Te flon 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 ammoni um concentrations. I don’t know much about sampling for biological materials, but think ther e must be other useful options beyond SEM and Protein Assay. I’m not sure that SEM on Polycarbona te filters for fly ash can really be justified, except at sites where a substantial fly ash contribu tion is otherwise indicate d. 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 mo st harmful coarse particle mixtures. Then chemical &/or biological an alyses could be focused to the samples of interest.

Regarding mass balance issues, I think (assuming cr ustal oxides are appropriately estimated) that a large and likely variable fraction unmeas ured of non-carbon organi c 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 dic hotomous samplers, MetOne SASS speciation monitors, PM10 and PM2.5 FRMs are potential samp ling devices (with the appropriate filter types) for PM10-2.5 speciation. Among these samp ler types, which should be included or excluded from the pilot network design? Are ther e 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 st udy. 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 nitr ate on (denuded) dichot Ny lon? It would also

69be useful to evaluate any con tinuous speciation instruments, su ch 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 co arse 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 practi ces to minimize such losses (if any).

3. What are the PM10-2.5 specia tion sampling artifacts that ma y be encountered using the samplers mentioned above and how should they be addressed? Is speciation by the difference method problematic for PM10-2.5 sp eciation 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 ne eded (nor would ammonium measurements like reflect ambient concentrations). Coarse nitrat e might be measured directly from Quartz or

Teflon dichot filters. Loss of some chloride is like ly 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 relative ly high concentrations

in the fine mode.

4. The current and most widely used PM2.5 sp eciation 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, especial ly 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 st arting out with a strong advance signal that the mass of coarse particles is a good health indicator. Achi eving a mass balance is less important than understanding where the various co mponents 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 fo r analyses such as mol ecular carbon compounds or specific biological components which ma y require very large sample sizes.

PM10-2.5 Species or Components

1. Table 1 provides a list of proposed PM 10-2.5 species and analysis methods. Among these species, which are most important? Are ther e important PM10-2.5 species or components missing from this list? Are there important analysis methods missing from this list?

70See answers to Q 1 under Speciation Measurement Issues. My preference for a minimum Coarse speciation measurement (for the most sites) woul d be a dichot with XRF and optical absorption on a Teflon coarse filter. My next addition woul d be a dichot with quartz filters for carbon and ion analysis. Paired (difference method) or vi rtual 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 analys es 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 dominati on of coarse mode formation or suspension

mechanisms.

2. In the consideration of potential ion meas urements 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 co llection of these sp ecies in PM10-2.5?

See previous answers. I don’t see why there shou ld be much coarse ammonium nitrate in the ambient air, and I expect coarse nitrate compoun ds (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 whic h included biological materials and fly ashes. If these species are im portant to characterize, what specific types of biological materials and fly ashes should be incl uded? 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 as h SEM is generally warranted unless otherwise indicated. For more input on appropriate routine and/or at least occasiona lly feasible biological (sampling and) analyses, you may want to cons ult beyond this subcommittee. See for example Dale Griffin’s (USGS) paper on: Atmospheri c Movement of Microorganisms in Clouds of Desert Dust and Implications for Human Hea lth, Clinical Microbiology Reviews, July 2007, p. 459-477, Vol. 20, No. 3, http://cmr.asm.org/cgi/content/fu ll/20/3/459?view= long&pmid=17630335

In the arid Southwest some specific analyses fo r 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?

71Not my area of expertise. I would imagine th at reasonable correction fa ctors can be developed.

5. Are metal oxides a significant source of inte rference in thermal-optical analysis (TOA) of PM10-2.5 for OC and EC given the large expecte d soil component? If so, how should this interference be addressed?

Not my area of expertise. I would imagine th at reasonable correction fa ctors 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 monito ring sites with PM10-2.5 speciation, what other factors should be considered in se lecting the pilot monitori ng 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 weakne sses of different sampling and size-separation techniques. However, I think a few such sites sh ould probably be included in both the pilot and longer-term networks and speci fically include sites heavily influenced by: windblown dust, agricultural activ ities, mining activities and industrial process emissions. In the pilot study, it would also be useful to challenge the size sepa ration methods by including sites with relatively high fine to coarse ratios. It would also be desirable to includ e 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 expect ed at NCore locations compared to locations

closer to sources. A few rural coastal sites on th e West Coast in the far Southeast – such as the Redwood, Point Reyes, Everglades or Virgin Is land 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 sp eciation monitoring requirements during a future rulemaking, should changes to th e 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 th e EPA staff memo and by the members of this review committee regarding sampling and analytical methods, analytes and s ite 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 NCor e 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 networ k, and other developments, it may be logical to consider changes to the proposed NCor e coarse particle speciation network.

Possibly, many of the NCore sites which are othe rwise very well suited for assessment of multiple pollutant exposures may not be idea lly sited for measuring coarse particle concentrations, compositions and representative exposures. I think it would be useful to

72intentionally 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 even ts, etc. Seasonal compositing of samples may also be a useful technique to allow more sophi sticated measurements such as for molecular carbon compounds, which require large sample sizes or are too costly fo r routine application.

I think an important complement to a coarse speciation network, and something that would enhance the value of existing fine speciation mon itoring sites as well, would be to conduct an emissions characterization program in which so urce emissions are characterized by exactly the same sampling and analytical methods that are ap plied for ambient sampling (including both fine and coarse fractions which togeth er 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 monitori ng 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 dic hots with Teflon filters and XRF and optical absorption analysis – or possibly a second dichot with quartz filter s for carbon and ion analysis). Additional samplers, higher sample frequencies, c ontinuous 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 inte resting 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 provide d to support NCore “L evel 1 sites”, the concept is a good one and it might be especially applicable for coarse particle speciation monitoring, as it seems likely th ere will be a lingering need to develop and evaluate new sampling and analytical methods (at a few site s) 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 (PM 10-2.5 , 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 observ ed 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 findi ngs from the pilot network towards optimizing the measurement strategy. In my opinion, optim ization of sampling hardware and monitor siting guidance (based on early results from the pilot ne twork) should take precedence over meeting the January 1, 2011, date for full deployment of the PMc network at NCore s ites. If the deployment date is delayed, the Agency should provide an ex planation of the reason(s) for the delay, the remaining work to be done, and the revised timeline for network deployment.

PM 10-2.5 Speciation Measurement

1. Table 1provides a list of proposed PM 10-2.5 species and analysis methods. Are there

additional PM 10-2.5 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 (ame nded from the white paper, and referring to the Agency presentation at the February 9 telec onference) meet two objec tives – identifying the major chemical components needed to reconstruc t PMc mass (as stated in the charge question) and providing additional information about emi ssion sources and their re lative contributions. Priority should be given to the analyses needed for mass balance closure and this subset of the

list should contain the conventi onal 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 im portant for only a limited number of environments. Thus, the carbonate carbon analysis is reco mmended 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 dic hotomous samplers, MetOne SASS speciation
monitors, PM 10 and PM 2.5 FRMs are potential sampling devices (with the appropriate filter types) for PM 10-2.5 speciation. Among these sampler types, wh ich should be included or excluded from the pilot network design? Are there other sa mpling devices not listed here that should be

considered?

All of these samplers have advantages and disa dvantages as has been discussed in previous

deliberations of this subcommittee. Paired PM 10 and PM 2.5 FRMs might be most challenged at sites with relatively high PM 2.5 /PM 10 ratios because the measurements uncertainties propagate for these independent measurements. This does not necessarily preclude the use of paired PM 10

74and PM 2.5 FRMs, but their suitability should be eval uated 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 PM 2.5 and PM 10 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 se ts collected by the Agency, which can be used to probe this issue). At this time, I give prio rity to dichotomous samplers. Hi storically, one concern has been the potential for losses from the coarse particle f ilters during handling and shipping since the fine particles present in a conventional PM 10 sample act as “glue”. I recall the Agency examined this

issue in their recent PMc characte rization field campaign. If it is deemed an issue there might be simple ways to stabilize the deposit on the filt ers prior to shipping. Samplers with multiple sampling channels, such as used in the CSN ne twork, are preferred because they allow the collection of particles on differe nt filter media using a single sampler. However, the use of parallel samplers (a one samp ler-one substrate approach), su ch as used in the IMPROVE network, has proven to be robust. In either case, the design shoul d 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 m onitor 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 importa nt for emission source identification, especially if paired with XRF instead of ICP-MS.

3. What are the PM 10-2.5 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 PM 10-2.5 speciation and if so what specif ic issues make it problematic?

It will be helpful to understand how the virtua l impactor cutpoint cu rve compares to the PM 2.5 FRM cutpoint curve. The PM 2.5 FRM impactor has been charact erized in detail, and we know that the cutpoint curve is rela tively broad (by design). The di chotomous sampler (or any other sampler being deployed) should also have a well-c haracterized cutpoint with this information ideally available when interpreting data from the pilot network, The white paper addresses potential artifact issues c oncerning 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 fo rm of coarse PM nitrate based on the data

collected to date. It would be id eal to evaluate the importance of denuders as part of the pilot

network measurements.

4. The current and most widely used PM 2.5 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

PM 10-2.5 mass or the dichotomous sampler (16.7 Lpm). If this sampler was configured for PM 10-

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 PM 10-2.5 FRM?

The low flow rate for the MetOne SASS might ind eed be an issue for trace elements if XRF is the de facto analytical method, further compound ed 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 rega rding element-specific recoveries, cost, etc.

75Certainly another layer of complexity is a dded when comparing reconstructed mass from samples collected at one flow ra te to the mass collected by the PM 10-2.5 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 pu lled through the inlet (i.e. upstream of the virtual impactor).

PM 10-2.5 Species or Components

1. Table 1 provides a list of proposed PM 10-2.5 species and analysis methods. Among these species, which are most impor tant? Are there important PM 10-2.5 species or components missing from this list? Are there important an alysis methods missing from this list?

The core species measurements should be elem ents, ions, and ECOC, c onsistent with the PM 2.5 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 importa nt for source identification.

2. In the consideration of poten tial ion measurements for PM 10-2.5 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 PM 10-2.5 ?

The target list for ions is reasonable. While c onventional wisdom says a denuder is needed for high quality nitrate measurements, work perfor med for the IMPROVE program has shown that certain inlets can be quite effective denudi ng nitric acid (although I don’t know about the extrapolation of these results to urban environments). Sampli ng with and without denuders should be performed in the pilot network to dete rmine 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 PM 10-2.5 components which included biological materials and fly ashes. If these species are im portant to characterize, what specific types of biological materials and fly ashes should be incl uded? 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 character ization 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 so me issues in teasing out a fly ash signature from a soil signature from the elemental data).

764. Can the complication of particle size and abs orption effects in XRF be resolved using absorption correction factors? If not, w hat 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 inte rference in thermal-optical analysis (TOA) of

PM 10-2.5 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 su ch 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 PM 10

and low PM 2.5 good candidate sites for PM 10-2.5 speciation? Given that there will be some urban and rural NCore monitoring sites with PM 10-2.5 speciation, what other factors should be consider ed in selecting the pilot mon itoring and long-term sites or

locations?

The focus should not be excl usively on sites with high PM 10 and low PM 2.5 . The pilot sites should be chosen to represent a broad range of aerosol compositions and environmental conditions, with the results being used to refi ne the recommendations for which Ncore sites should have PMc speciation. There ar e other considerations, such as providing data sets of use to health scientists, which would s upport the selection of sites to collectively include a range of

PMc levels.

2. If there is an opportunity to modify the NCore PM 10-2.5 speciation monitoring requirements during a future rulemaking, should changes to th e network design be considered? For example, changing the total number of required monitors and/or the required locations?

See my introductory comment which addresses th e timeline for network deployment. At this point, I have no additional comm ents about the network design.

77

### Dr. Warren H. White

PM 10-2.5 Speciation Measurement

I will start by recognizing, and commending, th e 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 hug e commitment of resources that might otherwise

be devoted to more time-resolved measuremen ts, or to biochemical assays and other new approaches to sample characterization, or to nuclei counters and ot her instruments more responsive to ultra-fine particles. Any one of these alternatives to the straightforward extension

to PM 10-2.5 of current PM 2.5 measurements might yield greater in sight into which particles should be of greatest concern to regulat ors. I urge the Agency to de lay the general introduction of PM 10-

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 PM 10-2.5 speciation monitoring primarily for scientific purposes...”

It’s not at all clear to me what those scient ific 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 PM 2.5 speciation network, don’t seem very well adapted to either of these.

Source attribution: We have considerable experience wi th source attribution using speciated

PM 2.5 data. That experience has taught us that it is hard to distinguish between different carbonaceous sources using EC and OC from therma l-optical analysis, and that it is hard to distinguish between different sources of dust usi ng elemental analysis. But organic and crustal materials make up the bulk of PM 10-2.5 nearly everywhere. So what can the proposed level of speciation do? It can distingui sh smoke from dust, but how of ten do local agencies encounter high PM 10-2.5 that they can’t easily associate with obvi ous local and regional sources of smoke or

dust?

Hazard assessment: Its 2005 assessment of the epid emiological evidence lead EPA to “consideration of thoracic coarse urban particulate matter (UPM 10–2.5 ) as an indicator for a thoracic coarse particle standard ... qualified so as to include any ambient mix of PM 10–2.5 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

PM 10–2.5 that is dominated by rural windblow n dust and soils and PM generated by agricultural and mining sources.”

In other words it judged that dusts of crus tal origin, benign in ru ral settings, became contaminated in cities with surface coatings and othe r urban grime. It will be hard to detect such

trace contaminants in PM 10-2.5 samples with the bulk chemical analyses currently used with

PM 2.5 ; it will be still harder against a background of chemically-similar PM 2.5 mixed in with a

PM 10 sample. The pilot study should give particular attention to analytic al methods that can target specific fractions exp ected to be enriched in PM 10-2.5 , such as biological markers.

78Reference

NRC (2004) Research Priorities for Airborne Partic ulate Matter IV: Co ntinuing Research Progress. National Academies Press, Washington.

79

### Dr. Yousheng Zeng

PM 10-2.5 Speciation Measurement

Among the four filter-based sampler types, dichot omous samplers should be used for speciation measurement. Dichotomous samplers produce physically separate coarse samples for speciation chemical analysis, which in turn reduces interfer ences 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

PM 2.5 sample and PM 10 sample are close (i.e., the compone nt primarily associated with PM 2.5 ),

the difference between the two measurements may be too small compared to analytical uncertainty, making the speciation measurement unr eliable. This problem is more significant when the chemical analysis has a sufficien t method detection limit, but poor precision (repeatability). In that case, if dichotomous sa mplers are utilized, the results will be more

reliable.

Even though dichotomous samplers are not FR M for PM mass measurement, their deviation from FRM, if any, is small. Considering uncer tainties associated with many chemical analyses at low concentration levels, this possibly small deviation should be acceptable.

PM 10-2.5 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 appo rtionment. Also, ultimate analysis may help

close the mass difference. I am not su re this will be feasible or prac tical. I just want to bring this up for EPA to consider for the pilot sites.

Network Design

For selection of pilot sites, high PM 10 and low PM 2.5 sites should give more PM coarse fraction to work with. However, I think it is also importa nt to select some pilot sites that represent low

PM 10 and high PM 2.5 . At these sites the PM coarse fract ion would be low. It would be a good test to see how the speciation methods perform wh en the coarse fraction is low (e.g., will method detection limits be low enough to cover some im portant species). Also , when EPA considers high or low PM 10 or PM 2.5 , EPA should consider not only the ratio between PM 10 and PM 2.5 , but

also the mass levels of PM 10 and PM 2.5 . 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

PM 10-2.5 Speciation Measurement

1. Table 1 provides a list of proposed PM 10-2.5 species and analysis methods. Are there

additional PM 10-2.5 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 PM 10-2.5 organic compounds. Taking into account that organic carbon (OC) constitutes significant portion of PM 10-2.5 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 anth ropogenic? This knowledge may have important health implications and so fa r is missing. Since the primary objective for PM 10-2.5 speciation data is to support further research in understanding their chemical composition and source, the importance of the organic mass speci ation 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 re presentative 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 iden tification of as many orga nics as possible to get some knowledge of the organic mass composition of coarse particles in different locations. PM 10-

2.5 is very different from PM 2.5 and the source tracers that worked for fines may not work for coarse particles.

2. Various sampling devices, including dichot omous samplers, MetOne SASS speciation
monitors, PM 10 and PM 2.5 FRMs are potential sampling devices (with the appropriate filter types) for PM 10-2.5 speciation. Among these sampler types, wh ich should be included or excluded from the pilot network design? Are there other sa mpling devices not listed here that should be

considered?

PM 10 and PM 2.5 FRM are not appropriate for speciation of PM 10-2.5 , since when the fine and coarse particles are mixed together, their com position can be potentially altered. Also, the determination of chemical composition by a differen ce method is inherently less precise and it is virtually impossible for organic compound’s specia tion. Although volatility issues are likely less important for PM 10-2.5 , they are important for PM 2.5 , which may bias the results of the difference method. Dichotomous sampler (or equiva lent), which provides a separate PM 10-2.5 fraction are more appropriate for chemical speciation. In addition, continuous methods for mass meas urements and OC/EC speciation should be encouraged.

3. What are the PM 10-2.5 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 PM 10-2.5 speciation and if so what specif ic issues make it problematic?

See my answer to Question #2.

814. The current and most widely used PM 2.5 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

PM 10-2.5 mass or the dichotomous sampler (16.7 Lpm). If this sampler was configured for PM 10-

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 PM 10-2.5 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 f unction of the inlet flow, this should not be a problem.

PM 10-2.5 Species or Components

1. Table 1 provides a list of proposed PM 10-2.5 species and analysis methods. Among these species, which are most impor tant? Are there important PM 10-2.5 species or components missing from this list? Are there important an alysis 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 s ource attribution and mass

closure.

2. In the consideration of poten tial ion measurements for PM 10-2.5 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 PM 10-2.5 ?

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 PM 10-2.5 components which included biological materials and fly ashes. If these species are im portant to characterize, what specific types of biological materials and fly ashes should be incl uded? 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 s ources (fly ashes were removed from Table 1 presented by Joann Rice). SEM on Te flon 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, et c. However, this assay is not adequate as an indicator of the total biological material presen t. Plant or soil derived material may be an important contributor. Analysis of sugars, sugar alcohols, phytost erols, triterpenoids, etc., may

8283 help in quantification and iden tification of types of biologica l materials present in coarse particles.

4. Can the complication of particle size and abs orption effects in XRF be resolved using absorption correction factors? If not, w hat other method(s) should be considered?

It would be desirable to comp are ICPMS with XRF during a pilot study to answer this question.

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

PM 10-2.5 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 ma terial or carbonates are anothe r potential interf ering species. This question should be addressed during a pilot study.

Network Design

1. Are sites with high PM 10

and low PM 2.5 good candidate sites for PM 10-2.5 speciation? Given that there will be some urban and rural NCore monitoring sites with PM 10-2.5 speciation, what other factors should be consider ed in selecting the pilot mon itoring and long-term sites or

locations?

It would be important to include both types of sites, with low and high PM 10 to PM 2.5 ratios. Especially in urban locations an d/or close to highways both type s may be important. Variations in geographical distribution, costal and inland lo cations, urban and rural sites, proximity of mining sources, etc., should also be considered.

2. If there is an opportunity to modify the NCore PM 10-2.5 speciation monitoring requirements during a future rulemaking, should changes to th e 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 PM 10-2.5 speciation sites, the throughout evalua tion of pilot study data should be completed. It seems that a goal of launching long-term PM 10-2.5 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.