UNITED STATES ENVIRONMENTAL PROTECTION AGENCY
° WASHINGTON D.C. 20460
April 14, 2008
EPA-CASAC-08-010
OFFICE OF THE ADMINISTRATOR
SCIENCE ADVISORY BOARD
Honorable Stephen L. Johnson
Administrator
U.S. Environmental Protection Agency
1200 Pennsylvania Avenue, NW
Washington, DC 20460
Subject: Clean Air Scientific Advisory Committee (CASAC) Ambient Air Monitoring
& Methods (AAMM) Subcommittee Consultation Concerning Ambient Air
Monitoring Issues related to the Lead NAAQS
Dear Administrator Johnson:
EPA's Clean Air Scientific Advisory Committee (CASAC) Ambient Air Monitoring &
Methods (AAMM) Subcommittee held a public advisory teleconference meeting on March 25,
2008, to conduct a consultation with staff from EPA's Office of Air Quality Planning and Stan-
dards (OAQPS), within the Office of Air and Radiation, on ambient air monitoring issues related
to the National Ambient Air Quality Standards (NAAQS) for lead, including issues associated
with alternative lead indicators.
The SAB Staff Office has developed the consultation as a mechanism to advise EPA on
technical issues that should be considered in the development of regulations, guidelines, or tech-
nical guidance before the Agency has taken a position. A consultation is conducted under the
normal requirements of the Federal Advisory Committee Act (FACA), as amended (5 U.S.C.,
App.), which include advance notice of the public meeting in the Federal Register.
As is our customary practice, there will be no consensus report from the CASAC as a re-
sult of this consultation, nor does the Committee expect any formal response from the Agency.
The current CASAC AAMM Subcommittee roster is attached as Appendix A of this letter, Sub-
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committee members' individual written comments are found in Appendix B, and the Agency's
background and charge memorandum to the Subcommittee is provided in Appendix C.
Sincerely,
/Signed/
Dr. Armistead (Ted) Russell, Chair
CASAC AAMM Subcommittee
Attachments
cc: Marcus Peacock, Deputy Administrator
Robert Meyers, Acting Assistant Administrator, OAR
Dr. Rogene Henderson, CASAC Chair
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Appendix A - Roster of the CASAC Ambient Air Monitoring & Methods
(AAMM) Subcommittee
U.S. Environmental Protection Agency
Clean Air Scientific Advisory Committee (CASAC)
CASAC Ambient Air Monitoring & Methods (AAMM) Subcommittee
CASAC MEMBERS
Dr. Armistead (Ted) Russell (Chair), Georgia Power Distinguished Professor of Environmental Engi-
neering, Environmental Engineering Group, School of Civil and Environmental Engineering, Georgia
Institute of Technology, Atlanta, GA
Dr. Ellis Cowling, University Distinguished Professor At-Large, Emeritus, Colleges of Natural Re-
sources and Agriculture and Life Sciences, North Carolina State University, Raleigh, NC
Dr. Donna Kenski, Director of Data Analysis, Lake Michigan Air Directors Consortium (LADCO),
Rosemont, IL
SUBCOMMITTEE MEMBERS
Mr. George Allen, Senior Scientist, Northeast States for Coordinated Air Use Management
(NESCAUM), Boston, MA
Dr. Judith Chow, Research Professor, Desert Research Institute, Air Resources Laboratory, University
of Nevada, Reno, NV
Mr. Bart Croes, Chief, Research Division, California Air Resources Board, Sacramento, CA
Dr. Kenneth Demerjian,* Professor and Director, Atmospheric Sciences Research Center, State Univer-
sity of New York, Albany, NY
Dr. Delbert Eatough, Professor of Chemistry, Emeritus, Chemistry and Biochemistry Department, Brig-
ham Young University, Provo, UT
Mr. Eric Edgerton, President, Atmospheric Research & Analysis, Inc., Gary, NC
Mr. Henry (Dirk) Felton, Research Scientist, Division of Air Resources, Bureau of Air Quality Surveil-
lance, New York State Department of Environmental Conservation, Albany, NY
Dr. Philip Hopke, Bayard D. Clarkson Distinguished Professor, Department of Chemical Engineering,
Clarkson University, Potsdam, NY
Dr. Rudolf Husar, Professor, Mechanical Engineering, Engineering and Applied Science, Washington
University, St. Louis, MO
A-l
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Dr. Kazuhiko Ito, Assistant Professor, Environmental Medicine, School of Medicine, New York Univer-
sity, Tuxedo, NY
Dr. Thomas Lumley, Associate Professor, Biostatistics, School of Public Health and Community Medi-
cine, University of Washington, Seattle, WA
Dr. Peter McMurry,* Professor, Department of Mechanical Engineering, Institute of Technology, Uni-
versity of Minnesota, Minneapolis, MN
Mr. Richard L. Poirot, Environmental Analyst, Air Pollution Control Division, Department of Envi-
ronmental Conservation, Vermont Agency of Natural Resources, Waterbury, VT
Dr. Kimberly Prather, Professor, Department of Chemistry and Biochemistry, University of California,
San Diego, La Jolla, CA
Dr. Jay Turner, Visiting Professor, Crocker Nuclear Laboratory, University of California - Davis, Davis,
CA
Dr. Warren H. White, Research Professor, Crocker Nuclear Laboratory, University of California -
Davis, Davis, CA
Dr. Yousheng Zeng, Air Quality Services Director, Providence Engineering & Environmental Group
LLC, Providence Engineering and Environmental Group LLC, Baton Rouge, LA
Dr. Barbara Zielinska, Research Professor, Division of Atmospheric Science, Desert Research Institute,
Reno, NV
SCIENCE ADVISORY BOARD STAFF
Mr. Fred Butterfield, Designated Federal Officer, 1200 Pennsylvania Avenue, N.W., Washington, DC,
20460, Phone: 202-343-9994, Fax: 202-233-0643 (buttoficMJTCdiaicEa.gov) (Physical/Courier/FedEx
Address: Fred A. Butterfield, III, EPA Science Advisory Board Staff Office (Mail Code 1400F), Woodies
Building, 1025 F Street, N.W., Room 3604, Washington, DC 20004, Telephone: 202-343-9994)
*Dr. Demerjian and Dr. McMurry did not participate in this CASAC AAMM Subcommittee activity.
A-2
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Appendix B - Comments from Individual CASAC
AAMM Subcommittee Members
This appendix contains the preliminary and/or final written comments of individ-
ual members of the Clean Air Scientific Advisory Committee (CASAC) Ambient Air
Monitoring & Methods (AAMM) Subcommittee. The comments are included here to
provide both a full perspective and a range of individual views expressed by Subcommit-
tee members during the consultation process. These comments do not represent the
views of the CASAC AAMM Subcommittee, the CASAC, the EPA Science Advisory
Board, or the EPA itself. Panelists providing written comments are listed on the next
page, and their individual comments follow.
B-l
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Panelist Page#
Mr. George Allen B-3
Dr. Judith Chow B-6
Dr. Ellis Cowling B-18
Mr. Bart Croes B-20
Dr. Delbert Eatough B-24
Mr. Dirk Felton B-26
Dr. Philip Hopke B-35
Dr. Rudolf Husar B-37
Dr. Kazuhiko Ito B-38
Dr. Donna Kenski B-42
Dr. Armistead (Ted) Russell B-45
Dr. Jay Turner B-48
Dr. Warren H. White B-52
Dr. Yousheng Zeng B-54
Dr. Barbara Zielinska B-56
B-2
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Mr. George Allen
To: Fred Butterfield, Designated Federal Officer
EPA SAB, Clean Air Scientific Advisory Committee (CASAC)
Ambient Air Monitoring and Methods Subcommittee (AAMM)
From: George Allen, AAMM subcommittee member, April 1, 2008
The following are written comments based on the Charge Questions in the EPA OAQPS memo
to the SAB dated March 3, 2008. These comments also reflect discussion during the March 25
teleconference advisory meeting on a consultation for air monitoring issues related to the lead
National Ambient Air Quality Standards. A copy of these comments is also being sent to Dr.
Ted Russell, CASAC AAMM Subcommittee Chair.
Questions associated with Attachment 1: Options for Lead NAAQS Indicator: Monitoring Im-
plications.
1. ...please describe the advantages and disadvantages of sampling and analysis of Pb-TSP ver-
sus sampling and analysis of Pb-PMlO.
2. Is it appropriate to monitor for Pb-PMlO near Pb sources? And if so, under what conditions?
3. One indicator option suggests using scaling Pb-PMlO monitoring data up to an equivalent
Pb-TSP level in lieu of Pb-TSP monitoring data. Under what circumstances would it be appro-
priate to scale data (e.g., non-source oriented sites, low concentration sites) and when would it
not be appropriate to scale data?
4. We have limited data collocated Pb-PMlO and Pb-TSP monitoring data. What types and
"scaling factors" are appropriate to create using this data (e.g., non-source oriented, source ori-
ented)? What levels are appropriate for the types of scaling factors identified in the white paper?
Comments:
Assuming the Pb NAAQS is substantially tightened to the high end of the CASAC range (0.2
ug/m3), I see no significant disadvantage in changing to PM10 as the routine indicator, and a
wide range of advantages in not running Hi-Vol samplers. If we are changing the standard and
network design to reflect current knowledge of lead sources and exposures, changing to a
method that gives air agencies more flexibility can only be a good thing. If there are elevated
levels of lead (relative to the new NAAQS), they are likely to be source oriented. A PM10 lead
sample may (worst case) measure only half of what a Hi-Vol TSP sampler might, but one will
still know there is a problem with fugitive lead emissions and a need for a control strategy. I am
not in favor of any "scaling" approach when it comes to compliance lead monitoring. The con-
nection between levels of lead measured in the air and actual dose of lead to sensitive popula-
tions is loose at best and random at worst, given the dominant exposure pathways. If there is
concern about PM10 measuring somewhat less lead than TSP, have the standard reflect that by
adding an additional margin of safety. If the lead NAAQS drops an order of magnitude, that is
not much of an issue. However, if the revised lead NAAQS does not change, or is tightened only
a modest amount or weakened by the form, then a scaling factor may be needed.
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Questions associated with Attachment 2: Draft Federal Reference Method (FRM) and Federal
Equivalent Method (FEM) Criteria for Lead in PM10 (Pb-PMlO):
1. Is it appropriate to use the low-volume PMlO-c FRM sampler as the Pb-PMlO FRM sampler?
2. What other PM10 samplers should be considered as either FRM or FEM for the Pb-PMlO
FRM?
3. Is XRF an appropriate Pb-PMlO FRM analysis method?
4. What other analysis methods should be considered for FRM or FEM for the Pb-PMlO FRM?
5. Have we selected appropriate precision, bias, and method detection limit requirements for
FEM evaluation?
Comments:
This attachment is very well written with only minor omissions. It is appropriate to use the low-
volume PMlO-c FRM sampler as the Pb-PMlO FRM sampler. Sequential PM10 samplers
should also be allowed, either as FRM or FEM samplers. The dichotomous sampler is an obvi-
ous candidate for an FEM sampler for lead. While XRF may be appropriate for an FEM analyti-
cal method, ICPMS or GFAA should be used for the FRM analytical method since those meth-
ods do not have the potential for arsenic interference that XRF has. When properly done, using
all three lead emission peaks to assess and correct for arsenic interference, XRF is suitable for
routine lead analysis under an FEM designation. It should be noted that other elements may suf-
fer from self-absorption errors with heavily loaded filters, so some caution may be needed if all
reported XRF elements are used for other purposes. The bias and method detection limits in this
draft are appropriate. I would suggest that the FEM precision be tightened from 15% to 10%.
Questions associated with Attachment 3: Lead NAAQS Ambient Air Monitoring Network:
Network Design Options Under Consideration.
1. What types of monitoring sites should be emphasized in the network design (e.g., source ori-
ented monitors, population monitors, near roadway monitors)?
2. We are considering proposing requirements for monitoring near sources exceeding an emis-
sions threshold and discuss a number of options for determining this threshold in the white paper.
What options should be considered in establishing an emissions threshold?
3. We are considering proposing requirements for non-source oriented monitoring in large urban
areas to provide additional information on ambient air concentrations in urban areas.
Considering other monitoring priorities and a potential requirement for Pb monitoring near
sources, what size of a non-source oriented Pb network is appropriate?
4. What factors should we base non-source oriented monitoring requirements on (e.g., popula-
tion, design value)?
5. We are considering proposing requirements for Pb monitoring near roadways and interstates.
Is it appropriate to include separate monitoring requirements for near roadway monitoring, or
should near roadway monitors be a part of the non-source oriented monitoring requirement?
6. Under what conditions would it be appropriate to waive the monitoring requirements for ei-
ther source or non-source oriented monitors?
Comments:
First, not knowing what the final lead NAAQS will be (including the form, not just the concen-
tration), it is very difficult to comment on network design. But assuming the final NAAQS will
not be lower than 0.2 ug/m3, with a form that does not substantially weaken the effective stan-
B-4
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dard, I would suggest the network focus on source and population oriented sites. For source ori-
ented sites, assuming the emissions are reasonably well known one could model the near-field
impact to determine if monitoring is necessary. Alternatively, if there is large uncertainty in
emissions, limited preliminary monitoring could be deployed to determine if the ambient impact
of the source requires additional or continued monitoring. Non-source ambient monitoring, e.g.,
neighborhood to urban scale siting, should consider both the design value and to a lesser extent,
the population. We don't want to have a large (big-city) urban network of lead monitoring if all
the sites are well below the NAAQS. For near-roadway monitoring, this also depends on the
level and form of the NAAQS, but I would recommend only a limited monitoring (e.g., pilot)
effort for this source at least initially until more is known about both the extent of elevated lead
air concentrations near roadways as well as the value and form of the final lead NAAQS. As for
waiving or modifying monitoring requirements, if it can be shown by historical data or other rea-
sonable approaches that lead air levels are well below the NAAQS, then less monitoring should
be done.
Questions associated with Attachment 4: Lead NAAQS Ambient Air Monitoring Network:
Sampling Frequency Options Under Consideration.
1. What sampling frequency would be appropriate if the Pb NAAQS is based on a monthly av-
erage?
2. Is it appropriate to relax the sampling frequency in areas of low Pb concentration? If so, at
what percent of the Pb NAAQS?
3. Is it appropriate to relax the sampling frequency in areas considerably higher than the
NAAQS? If so, at what percent of the Pb NAAQS?
Comments:
First I want to clearly state that sampling frequency issues (and the level of public health protec-
tion) are highly dependent on not only the level of the NAAQS, but also the form of the
NAAQS; it is essential that any discussion on this topic include the form whenever a value is
mentioned. Sampling frequency for a simple monthly average NAAQS should be at least every
other day if not daily for sites that are near or above the NAAQS. If the form is "3-year average
of second highest month" (an option discussed in the staff paper), then every third day sampling
may be sufficient for sites near or above the NAAQS. It is appropriate to reduce sample fre-
quency at sites well below (50%?) the NAAQS, but again the sample frequency depends on the
form of the NAAQS. I would suggest third-day for a simple monthly mean, and sixth-day for a
"3-year mean of second highest month" form. I would also like to note that if a form similar to
"3-year average of second highest month" is adopted for the lead NAAQS, this would be incon-
sistent with the health concerns leading us towards a 1-month metric. Additionally, for a given
NAAQS value such as 0.2 ug/m3, a form as noted above results in a substantially weaker lead
NAAQS than a simple 1-month form.
B-5
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Dr. Judith Chow
From: Judith C. Chow, CASAC AAMM subcommittee member
Subject: Review of Ambient Monitoring Issues Related to Lead
This memo addresses the questions on which the Subcommittee members were asked to com-
ment regarding Attachment 1 ("Options for Lead NAAQS Indicator: Monitoring Implications"),
Attachment 2 ["Draft Federal Reference Method (FRM) and Federal Equivalent Method (FEM)
Criteria for Lead in PM10 (Pb-PM10)"], Attachment 3 ("Lead NAAQS Ambient Air Monitoring
Network: Network Design Options Under Consideration"), and Attachment 4 ("Lead NAAQS
Ambient Air Monitoring Network: Sampling Frequency Options Under Consideration").
Questions on Attachment 1 (Options for Lead NAAQS Indicator: Monitoring Implications)
Question 1: Considering issues such as sampler performance, size cuts, operator maintenance,
integration with other measurement systems, and usefulness as the measurement
system for the indicator, please describe the advantages and disadvantages of sam-
pling and analysis ofPb-TSP versus sampling and analysis ofPb-PMio.
The lead (Pb) national ambient air quality standard (NAAQS) was established in 1978 (U.S.EPA,
1978), when measurement technology for integrated samplers was limited to total sus-
pended particulates (TSP). EPA should move toward Pb-PMi0, which is inhalable and
can travel longer distances from emission sources.
Disadvantages: The TSP size fraction was defined by the dimensions of the high-volume (Hi-
Vol) sampler as specified in the code of Federal Regulations (Federal Register, 1975). It
is well known that HiVol TSP is non-size-specific, and EPA should consider phasing out
this old technology (Chow, 1995). By the end of the 1970s, efforts using wind tunnels to
characterize HiVol size-selection profiles showed that the 50% cut point of 30 - 50 jim
depended on the orientation of the sampler with respect to the direction and velocity of
the wind (Bruckman and Rubino, 1976; Chahal and Romano, 1976; Wedding et al., 1977;
Blanchard and Romano, 1978; McFarland et al., 1980; Swinford, 1980). The large open-
ing underneath the HiVol's peak roof inlet allows dust to blow onto the filter before and
after sampling between the every-sixth-day filter change. Given the non-size-specific na-
ture of the TSP samples and considering the question of how well Pb-TSP can represent
human exposure, this 1950s technology should be discontinued.
Advantages: The only advantage of keeping Pb-TSP is that a large body of Pb-TSP concentra-
tions have been obtained since 1980 (U.S.EPA, 2007) and the highest levels of Pb are
found near smelters and tailing piles (U.S.EPA, 2003). As shown in Figure 1, two areas
in the U.S. are designated as non-attainment for the Pb NAAQS due to recorded high Pb
concentrations (U.S.EPA, 2007). TSP data might be useful for long-term trend analysis
and to keep continuity with historical data, but given the large reductions already seen,
and the leveling of concentrations at most locations, this seems unnecessary.
B-6
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The low-volume (16.7 L/min) PMio inlet is wind-tunnel tested with specified collocated preci-
sion over a wide range of wind speeds and directions (Watson and Chow, 1993; 2001).
Low volume PMioc FRMs (Appendix O to Part 50) provide more flow control, low back-
ground Teflon-membrane filters, and more precise mass determination. It is also similar
to PM2.5 FRM (using the same PMio impactor inlet with the addition of WINS or sharp-
cut cyclone inlets). The low-volume PMiocFRM sampler is consistent with the EPA cur-
rent proposed difference method for PMio-2.5, which is similar (e.g., filter medium, sam-
ple collection, gravimetric analysis, quality assurance [QA]/quality control [QC]) to new
or existing PM data set(s). Since low-volume PMio samplers have been widely deployed
in many urban networks, they are commercially available and network operators are fa-
miliar with them, the cost for additional sampling and analysis should be reasonable.
There is no need for a separate Pb-PMi0 network. The integrated air monitoring strategy
(U.S.EPA, 2005) should be considered for Pb-PMi0 monitoring (Scheffe et al., 2007)
Counties Designated N on attainment for Lead
Figure 1. Non-attainment areas for lead (from
Question 2: Is it appropriate to monitor for Pb-PM]0 near Pb sources? And if so, under what
conditions?
Yes, Pb-PMio should be monitored near Pb sources, including roadways, mines (containing lead
ore), smelters, and tailing piles. The current -200 Pb-TSP sites are mostly located in ur-
ban areas, which may not represent near-source exposure. Since Pb additions to gasoline
were decreased in the early 1970s (Kitman, 2000), Pb-TSP content has decreased drasti-
cally, especially at urban sampling sites near freeways (U.S.EPA, 2007). Exposure to Pb
comes from multiple sources, including ingestion and inhalation, so important point
sources such as Pb smelters or areas with suspendable Pb tailings need to be considered.
Pb is still found in road dust, and decomposition of tire wheel weights has been suggested
as a potential source (Root, 2000). In addition to blood level Pb, the relationship between
air Pb and human exposure are critical (Bachmann, 2007). An evaluation of Pb emitters
B-7
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in the NEI (Attachment 3) is a good start. PMio levels near Pb sources should be moni-
tored under a variety of meteorological conditions and for extended periods, especially at
downwind locations where the concentrations are expected to be the highest.
Question 3: One indicator option suggests using scaling Pb-PMw monitoring data up to an
equivalent Pb-TSP level in lieu ofPb-TSP monitoring data. Under what circumstances
would it be appropriate to scale data (e.g., non-source oriented sites, low concentration
sites) and when would it not be appropriate to scale data?
Even though the analysis for measurements between 1993 and 2006 shows good correlations be-
tween Pb-TSP and PMio for 33 non-source-oriented sites, 40% of the Pb-TSP concentra-
tions were underestimated using linear regression. As noted earlier, and well-documented
in the scientific literature, the TSP fraction is ill-defined, not sampled consistently, has a
large fraction that deposits near the source, and is not as amenable to Pb analysis as PMi0.
A better question is: "What is the purpose for scaling Pb-PMio to an equivalent Pb-TSP
level?" Such scaling is rarely applicable to all situations. Without adequate collocation
under different meteorological conditions, scaling data always includes unaccountable
uncertainties. This exercise may be acceptable if the PMio data can be used to set up new
Pb-PMio NAAQS. The U.S. EPA should acquire Pb-PMio and analyze archived PMio
low-volume FRM samples to fill the gaps in the existing database.
Scaling data for source-oriented sites is even more difficult, since meteorological phenomena
may result in disproportional particle resuspension for TSP as compared to PMio and it is
more difficult to establish Pb-PMi0 and Pb-TSP relationships under high wind speeds.
Question 4: We have limited data collocated Pb-PMw and Pb-TSP monitoring data. What types
and "scalingfactors" are appropriate to create using this data (e.g., non-source ori-
ented, source oriented) ? What levels are appropriate for the types of scaling factors
identified in the white paper?
At the very least, different statistical methods (e.g., weighted least squares, effective variance
least squares, distribution of differences; (Watson and Chow, 2002; Mathai et al., 1984)
should be used to create the "scaling factor." Data should be aggregated by season and
segregated by wind sectors and wind speed to relate Pb-TSP to Pb-PMio or vice-versa. It
would be important to add a ± uncertainty to the scaling. Again, what is the purpose of
scaling?
Questions on Attachment 2 [Draft Federal Reference Method (FRM) and Federal Equivalent
Method (FEM) Criteria for Lead in PMIO (Pb-PM10)]
Question 1: Is it appropriate to use the low-volume PMwc FRM sampler as the Pb-PMw FRM
sampler?
Yes, as stated in the response to Question 1 of Attachment 1. A low-volume PMi0c FRM sampler
as the Pb-PMioFRM sampler is the most cost-effective way. There shouldn't be any
difference in low-volume PMioc samplers for PMio mass or Pb.
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Question 2: What other PMw samplers should be considered as either FRM or FEM for the Pb-
PM10FRM?
Although there are medium-volume and HiVol PMi0 FRM samplers (see Table 2 of Chow, 1995,
reproduced below) that can be considered as alternatives, many of them use 8" x 10"
quartz-fiber filters. Since Pb is a stable compound, retrospective Pb analysis can be done
on these samples by inductively coupled plasma (ICP), atomic absorption spectroscopy
(AAS), or XRF. Since many of the PMi0 high- or medium-volume FRMs are not com-
patible with the existing PM2.5 networks, it creates more variability in those networks and
is not as useful as low-volume PMi0c FRM samples.
Table % U S EPA designated reference and equivalent methods lor PM,.,
Sampler
iai Register Citation
(Notice Dale)
(Designation No)
1 Reference method
{RFPS-1087-Q62)
2 Reference method
fRFPS-1287-063)
Reference method
1287-064)
4.
5,
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Question 3: Is XRF an appropriate Pb-PMw FRM analysis method?
Yes, ringed Teflon-membrane filters are one of the best choices for XRF analysis of Pb, owing to
the high X-ray energy of the Pb L-a lines (10.55 and 12.61 ev), penetration into the filter,
and large-particle self-absorption aren't major issues. XRF is non-destructive, relatively
inexpensive, and can obtain other elemental concentrations as a bonus. It usually has low
blank levels for metals and is inert to adsorption of gases. The PM2.5 FRM network uses
Whatman (Hillsboro, OR) PTFE (poltytetra fluroethylene) Teflon-membrane filters,
which are 60% thicker than those from Pall Sciences (R2PJ047, 25 |im thickness, Ann
Arbor, MI), but this should not effect the minimum detectable limits (MDLs) of heavy
elements such as Pb. In the early 1990s, a batch of Teflon-membrane filters were con-
taminated with Pb, and that compromised study results, therefore acceptance testing of
low-volume PMio Teflon-membrane filters is essential before sampling (Chow, 1995).
The acceptance test should be set as 3 x MDL or 7 - 8 ng/cm2. Pb analysis by XRF is
highly sensitive, without much spectral interference. It can achieve MDLs of 1.5 - 2
ng/cm2 (Note that the MDL in Table 1 of Attachment 2 is 1.5 ng/cm2 and page 7 of Ap-
pendix Q to Part 50 shows 2.0 ng/cm2. 3 ng/cm2 is probably more reasonable.)
Question 4: What other analysis methods should be considered for FRM or FEMfor the Pb-
FRM?
There are quite a few modern analytical methods that can be used to quantify Pb. It can be ana-
lyzed by XRF, proton-induced X-ray emission (PIXE), flame ionization or graphite fur-
nace, AAS, ICP/atomic emission spectroscopy (ICP/AES), or ICP/mass spectrometry
(ICP/MS) (Watson et al., 1999). Table 1 shows the difference in MDLs among the differ-
ent methods. Switching from AAS to XRF is a good choice, since AAS is labor intensive,
subject to contamination during extraction, can only acquire a single element for a given
time, and requires lengthy acid extraction prior to chemical analysis.
Some XRF and PIXE instruments quantify elements with atomic numbers ranging from 1 1 (so-
dium) to 92 (uranium), although XRF usually acquires elements with lower MDLs as
compared to PIXE. It is non-destructive and requires neither sample preparation nor ex-
tensive operator time after samples are loaded into the analyzer. To achieve the greatest
benefit for the investment, EPA should consider acquiring all the elements listed in Table
1 using XRF (added costs will include acquiring a complete set of standards and to con-
duct spectral processing). If archived or other samples are acquired on quartz- or cellu-
lose-fiber filters, other analytical technology such as AAS or ICP can be considered,
though the equivalences needs to be achieved among different analytical methods.
B-10
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Table 1. Minimum detectable limits (MDLs) among the different methods.
Minimum Detectable Limit in ng/m3 a
Species
Ag
Al
As
Au
Ba
Be
Br
Ca
Cd
Ce
Cl
Co
Cr
Cs
Cu
Eu
Fe
Ga
Hf
Hg
I
In
K
La
Mg
Mn
Mo
Na
Ni
P
Pb
Pd
Rb
S
Sb
Sc
Se
Si
Sm
Sn
Sr
Flamee'f
INAAb'c
0.12
24
0.2
NA
6
NA
0.4
94
4
0.06
5
0.02
0.2
0.03
30
0.006
4
0.5
0.01
NA
1
0.006
24
0.05
300
0.12
NA
2
NA
NA
NA
NA
6
6,000
0.06
0.001
0.06
NA
0.01
NA
18
XRFb
6
5
0.8
2
25
NA
0.5
2
6
NA
5
0.4
1
NA
0.5
NA
0.7
0.9
NA
1
NA
6
3
30
NA
0.8
1
NA
0.4
o
J
1
5
0.5
2
9
NA
0.6
o
J
NA
8
0.5
PIXEbd
NA1
12
1
NA
NA
NA
1
4
NA
NA
8
NA
2
NA
1
NA
2
1
NA
NA
NA
NA
5
NA
20
2
5
60
1
8
o
J
NA
2
8
NA
NA
1
9
NA
NA
2
Graphite
AASe'g
4
30
100
21
8f
2f
NA
lf
1
NA
NA
6f
2
NA
4
21
4
52
2,000
500
NA
31
2f
2,000
0.3
1
31
0.2f
5
100,000
10
10
NA
NA
31
50
100
85
2,000
31
4
Furnacee'f
AASe'g
0.005
0.01
0.2
0.1
0.04
0.05
NA
0.05
0.003
NA
NA
0.02
0.01
NA
0.02
NA
0.02
NA
NA
21
NA
NA
0.02
NA
0.004
0.01
0.02
<0.05
0.1
40
0.05
NA
NA
NA
0.2
NA
0.5
0.1
NA
0.2
0.2
ICPeg
1
20
50
2.1
0.05
0.06
NA
0.04
0.4
52
NA
1
2
NA
0.3
0.08
0.5
42
16
26
NA
63
NA
10
0.02
0.1
5
NA
2
50
10
42
NA
10
31
0.06
25
o
J
52
21
0.03
ICP-MS11
0.000090
0.004098
0.000081
0.010000
0.000261
0.000400
NA
0.012675
0.000007
0.000003
NA
0.000006
0.003906
0.000015
0.001061
0.000004
0.015601
0.000039
0.000010
0.010000
NA
0.000009
0.007467
0.000003
0.001633
0.000102
0.000190
0.008134
0.000301
NA
0.000069
0.000024
0.000049
0.002621
0.000080
NA
0.000151
NA
0.000006
0.000076
0.000035
B-ll
-------
Table 1. Continued.
Minimum Detection Limit in ng/m
3a
Species
Ta
Th
Ti
Tl
U
V
w
Y
Zn
Zr
Flamee'f
INAAb'c
0.02
0.01
65
NA
NA
0.6
0.2
NA
3
NA
XRFb
NA
NA
2
1
1
1
NA
0.6
0.5
0.8
PIXEbd
NA
NA
3
NA
NA
o
J
NA
NA
1
o
J
Graphite
AASe'g
2,000
NA
95
21
25,000
52
1,000
300
1
1,000
Furnacee'f
AASe'g
NA
NA
NA
0.1
NA
0.2
NA
NA
0.001
NA
ICPeg
26
63
0.3
42
21
0.7
31
0.1
1
0.6
ICP-MSj
0.000576
0.000004
0.001016
0.000148
0.000004
0.000030
0.000187
0.000020
0.003051
0.000306
Minimum detection limit is three times the standard deviation of the blank for a filter of 1 mg/cm2 area! density.
ICP = Inductively Coupled Plasma Emission Spectroscopy.
ICP-MS = Inductively Coupled Plasma - Mass Spectrometry
AAS = Atomic Absorption Spectrophotometry.
PIXE = Proton Induced X-ray Emissions Analysis.
XRF = X-ray Fluorescence Analysis.
INAA = Instrumental Neutron Activation Analysis.
Concentration is based on 13.8 cm2 deposit area for a 47 mm filter substrate, with a nominal flow rate of 20
L/min for 24-hour samples.
Olmez, 1989.
Cahill, 1980.
Concentration is based on the extraction of 1/2 of a 47mm filter in 15 ml of deionized-distilled water, with a
nominal flow rate of 20 L/min for 24-hour samples.
Fernandez, 1989.
Harman, 1989.
Concentration is based on the digestion of 1/2 of a 47mm filter in 50 ml of acid, with a nominal flow rate of 20
L/min for 24-hour samples.
Not available.
Question 5: Have we selected appropriate precision, bias, and method detection limit require-
ments for FEM evaluation?
Precision, bias, and MDLs for a FEM should be no different from FRM for Pb analysis. Since
FEMs are usually installed at non-urban areas, MDLs for FEMs should be lower than
those of FRMs. MDLs of one tenth of NAAQS are recommended in Attachment 2. Why
should different MDLs be accepted for FRMs and FEMs? Five percent analytical accu-
racy, 15% precision, and 20% maximum difference as stated in Attachment 2 appear to
be reasonable. Pb and other heavy elements have been shown to be quantifiable on filter
tape deposits from FEM beta attenuation monitors (Watson et al., 2007).
B-12
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Questions on Attachment 3 (Lead NAAQS Ambient Air Monitoring Network: Network Design
Options Under Consideration)
Question 1: What types of monitoring sites should be emphasized in the network design (e.g.,
source oriented monitors, population monitors, near roadway monitors)?
Different types of sampling sites represent different receptor zones of representation based on
EPA's Guidance on Network Design Principles (Watson et al., 1997). Pb-PMi0 monitor-
ing should include both neighborhood-scale monitors (0.5 - 4 Km) for hot spots (e.g.,
smelters, tailing piles) and urban-scale (4 - 100 m) monitors for population exposure in
an urban environment (Chow et al., 2002). If elevated PMio appears to raise concerns
about public health near a specific source or sources, special studies should be conducted
(with more intense frequency at multiple locations) to assess the source zone of influ-
ences and to address the receptor zone of representation (Chow et al., 1999)
Question 2: We are considering proposing requirements for monitoring near sources exceeding
an emissions threshold and discuss a number of options for determining this threshold in
the white paper. What options should be considered in establishing an emissions thresh-
old?
Assuming the worst-case shown in Figure 2 of Attachment 1, Pb-TSP is 2.2 times Pb-PMio for
Pb-PMio NAAQS. This translates current 1.5 |ig Pb-TSP NAAQS to 0.68 |ig/m3 of Pb-
PMio. This value corresponds to median and maximum values of 0.3 |ig/m3 and 0.7
|ig/m3 per tons per year (tpy) for Pb emissions, respectively. There are 271 facilities in
the U.S. for a 1 tpy emission rate. As mentioned in Question 2 of Attachment 1, the NEI
is a good starting point, as are the estimations shown in Table 5 of Attachment 3 (e.g.,
379 sites for core-based statistical areas [CBSA] with populations > 100,000 people.
Note that the second Table 5 is the number of CBSAs).
Question 3: We are considering proposing requirements for non-source oriented monitoring in
large urban areas to provide additional information on ambient air concentrations in ur-
ban areas. Considering other monitoring priorities and a potential requirement for Pb
monitoring near sources, what size of a non-source oriented Pb network is appropriate?
The relationship between estimated emissions and observed ambient concentrations should be
established to determine an emissions threshold. The multi-layered network design for
the Pb surveillance network is a good start. EPA should correlate locations of current Pb-
TSP monitors (Figure 1 of Attachment 3) with those of Pb sources in NEI (Figure 2 of
Attachment 3). For example, Figure 1 of Attachment 3 shows that there are no Pb moni-
toring sites in Arizona, where Figure 2 of Attachment 3 shows large (> 5 - 15 tpy)
sources. Maybe the sources have been closed since the 2002 Inventory, but comparing
existing point sources to monitoring sites provides good knowledge for network design.
According to the U.S. EPA (2007; see Figure 1 above), only Jefferson County, MO and East He-
lena Area (Lewis & Clark County), MT are designated as non-attainment areas for Pb,
but Figure 1 of Attachment 3 doesn't show Pb-TSP monitoring near these sites. This type
B-13
-------
of discrepancy should be resolved. Statistical analyses based on existing data should also
be considered before sites are chosen.
Question 4: What factors should we base non-source oriented monitoring requirements on (e.g.,
population, design value) ?
Non-source oriented monitoring intends to represent human exposure in an urban scale (4-100
Km) or neighborhood scale (0.5 - 4 Km). CBSA is a good start for the basic number of
sampling sites. Even though Pb is a primary pollutant, and it may be localized, downwind
transport from large point sources needs to be considered at the regional scale (100 -
1,000 Km)
Question 5: We are considering proposing requirements for Pb monitoring near roadways and
inter states. Is it appropriate to include separate monitoring requirements for near road-
way monitoring, or should near roadway monitors be apart of the non-source oriented
monitoring requirement?
As less Pb was added to gasoline between 1978 and 1986, Pb emissions decreased substantially
(Bachmann, 2007). Even though mobile sources may contribute Pb from wheel weights
(i.e., ground up as road dust), brake wear, petro-fuels (traceable amounts) and lube oil,
Table 7 of Attachment 3 showed that maximum monthly Pb concentrations are below
0.05 |ig/m3; it is not clear how close the five selected sites are to roadways or other Pb
emitters. Unless EPA is considering a Pb-PMio NAAQS of <0.1 |ig/m3, roadside meas-
urements may not be a priority. Some roadside (hot spot) monitors should be part of the
normal PMio and PM2.5 networks, but it should not be necessary to perform these meas-
urements in every city, although special studies can be conducted at busy intersections to
address the spatial and temporal variations of Pb-PMio along with ultrafme particles (dp <
0.1 |im) measurements to address the issue of human exposure and potential health im-
pacts (Biswas and Wu, 2005; Chow et al., 2005).
Question 6: Under what conditions would it be appropriate to waive the monitoring require-
ments for either source or non-source oriented monitors?
This is a decision of EPA and should be consistent with decisions for other criteria pollutants.
Questions on Attachment 4 (Lead NAAQS Ambient Air Monitoring Network: Sampling Fre-
quency Options Under Consideration)
Question 1: What sampling frequency would be appropriate if the Pb NAAQS is based on a
monthly average?
The original proposal from EPA during the mid-1970s considered monthly average Pb-TSP. In-
dustry expressed a concern that the monthly maximum form of NAAQS would require
longer-term average Pb-TSP as low as 0.41 |ig/m3 to keep the maximum monthly below
1.5 |ig/m3. The one-in-six day sampling schedule is not adequate to determine the
monthly average (Supplemental Table 7 of Bachmann, 2007). If a monthly average is to
B-14
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be used, EPA would need to have a minimum of every third day sampling (i.e., ten sam-
ples/month).
Question 2: Is it appropriate to relax the sampling frequency in areas of low Pb concentration?
If so, at what percent of the Pb NAAQS?
It is reasonable to consider every sixth day sampling for areas with low Pb concentrations. The
30% Pb NAAQS proposed in Attachment 4 seems reasonable.
Question 3: Is it appropriate to relax the sampling frequency in areas considerably higher than
the NAAQS? If so, at what percent of the Pb NAAQS?
No. Areas with high Pb concentrations should keep at least an every third day sampling sched-
ule, and possibly a more frequent schedule. If facilities emit high concentrations of Pb
sporadically, daily sampling may be considered. Since suspended toxic dust might be a
large source, sampling and analysis should be more frequent during activities or meteoro-
logical conditions that enhance dust suspension.
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Harman, J.N. (1989). Inductively coupled plasma emission spectroscopy. InMethods of Air
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B-17
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Dr. Ellis Cowling
Dr. Ellis Cowling
North Carolina State University
March 29, 2008
Individual Comments following the March 25, 2008 Teleconference
Consultation by the Clean Air Scientific Advisory Committee (CASAC)
CASAC Ambient Air Monitoring and Methods (AAMM) Subcommittee
regarding Ambient Air Monitoring Issues related to the
National Ambient Air Quality Standards (NAAQS) for Lead (Pb)
As indicated during earlier consultations after review of plans for formulation and implemen-
tation of the NAAQS for lead, several colleagues on the CASAC Lead Review Panel are much
better prepared than I am by experience and scientific expertise to provide constructive com-
ments on air quality monitoring methods that are appropriate for airborne lead.
Thus, my natural predilection as a member of CASAC is to focus on general rather than spe-
cific aspects of the challenges involved including:
1) The importance and apparent lack of timeliness in implementation of some of EPA's respon-
sibilities for joining with other agencies of our federal and state governments in decreasing
airborne lead pollution in our country; and,
2) The very substantial and remarkably positive responsiveness of staff in EPA's Office of Air
Quality Planning and Standards to the several recommendations by CASAC with regard to
implementation of future primary and secondary NAAQS standards for airborne Pb pollution
including:
a) Switching from the current "Indicator" of airborne lead pollution [Pb in Total Suspended
Paniculate Matter (TSP)] to Pb in PMio, and
b) Decreasing the air concentrations of Pb that would be allowed under very substantially
more stringent NAAQS standards that appear to be necessary to protect public health and
public welfare from adverse effects of airborne Pb in the future.
Importance and Apparent Insufficiency of Past Efforts:
What an inspiration it was to learn that several different agencies of our Federal government
had committed themselves during the early 1990s to establishing a very worthy goal for envi-
ronmental protection "eliminating childhood lead poisoning [in the United States] by the year
2010!"
Prohibiting the use of Pb additives in gasoline and Pb-based pigments in house paints were
very substantial steps forward toward this noble goal.
But what a disappointment it has been also to recognize that these two major steps forward
have not been adequate to prevent the continuing adverse effects of airborne Pb on the IQ of
children in American society.
B-18
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The attached reference indicates that the currently proposed actions and reports regarding
lead pollution and resulting childhood lead poisoning in the United States are long overdue.
Childhood lead poisoning prevention. Too little, too late. B P Lanphear. J Amer Med
Assn. 2005 May, 293(18):2274-2276.
I commend the present administration of the USEPA for undertaking their apparently re-
newed interest and actions with regard to lead pollution and lead poisoning and hope that the
USEPA will now do an even larger share of its important part together with other agencies of
government and thus help our country make further progress toward achieving this very wor-
thy national goal if not by the year 2010 then as soon thereafter as possible!
Responsiveness of OAQPS Staff to Recommendations by CASAC's Lead NAAQS Review
Panel
During the recent CASAC Ambient Air Monitoring and Methods Subcommittee, Consulta-
tion, this Subcommittee was asked to review four important reports by staff within EPA Office
of Air Quality Planning and Standards:
1) "Options for Lead NAAQS Indicator: Monitoring Implications" by Kevin Cavender.
2) "Draft Federal Reference Method (FRM) and Federal Equivalent Method (FEM Criteria
for Lead in PM 10 (Pb-PMlO" by Joann Rice.
3) "Lead NAAQS Ambient Air Monitoring Network: Network Design Options Under Con-
sideration" by Kevin Cavender.
4) "Lead NAAQS Ambient Air Monitoring Network: Sampling Frequency Options Under
Consideration" by Mike Papp.
What a pleasure it was to see how very thoroughly each of these four reports gave earnest
attention to the several recommendations of the CASAC Lead Review Panel in their earlier letter
reports to the Administer of EPA with regard to options for lead NAAQS indicator, federal refer-
ence and federal equivalence methods of analysis, and both network design and sampling fre-
quency options under consideration!
The authors of each of these reports are to be commended for the thoroughness and clarity
with which their analyses and recommendations have been completed and presented for evalua-
tion by our CASAC Ambient Air Monitoring Subcommittee.
We hope this kind of thorough and positive responsiveness will be followed by similar con-
sideration of CASAC's other recommendations during the progress that must be made by the
USEPA in meeting the court-ordered deadlines for presentation of the:
Proposed Rule for lead NAAQS on May 1, 2008, and the
Final Rule for lead NAAQS on September 1, 2008 both of which are now less than two
months away, and less than six months away, from the date of this Ambient Air Monitoring and
Methods Subcommittee Consultation on March 25, 2008.
B-19
-------
Mr. Bart Croes
U.S. EPA's Pb NAAQS Review: Indicator and Monitoring Issues
March 25, 2008 Consultation Meeting
CASAC AAMM Subcommittee Review Comments, Bart Croes
Overall, the documents provided to the Subcommittee continue the impressive responsiveness by
U.S. EPA staff to CASAC and our Subcommittee's comments. Staff should be commended for
taking a systematic approach towards implementation of a likely revised lead (Pb) National Am-
bient Air Quality Standard (NAAQS). I appreciate the opportunity to comment during this in-
termediate stage of the process. The documents provide a good description of the issues and a
reasonable rationale for changes to the Pb Federal Reference Method (FRM) and Federal
Equivalent Method (FEM) process. I agree with the basic approach taken by U.S. EPA, and of-
fer comments on several aspects that need further attention. My comments address the consulta-
tion questions posed by Lewis Weinstock in his March 3, 2008 memo to Fred Butterfield. These
comments also reflect input from California Air Resources Board staff responsible for imple-
menting U.S. EPA monitoring requirements and using the data in source apportionment and
health studies.
Charge Questions:
Attachment 1 - Options for Lead NAAQS Indicator: Monitoring Implications
1. Considering issues such as sampler performance, size cuts, operator maintenance, integra-
tion with other measurement systems, and usefulness as the measurement system for the indi-
cator, please describe the advantages and disadvantages of sampling and analysis ofPb-TSP
versus sampling and analysis ofPb-PMlO.
The primary advantages of a PM10 size cut for Pb monitoring are that these are inhalable
particles (which are more relevant for human health effects from ambient air), the data is of
better quality, and there is a large existing PM10 monitoring network that can be adapted for
Pb monitoring.
However, the disadvantage is that super coarse particles that contribute to human health ef-
fects through ingestion by multi-media routes would be ignored. Also, there would be a dis-
connect with four decades of Pb-TSP data.
From a resources point of view, it makes most sense to build off of one of the existing net-
works (e.g., HiVol PM10, TSP Total Metals). The California Air Resources Board has a 20-
site Toxics Network (12 1pm TSP, Teflon filter, ICP/MS analysis) that we would like to see
considered as an option for meeting compliance requirements. By taking advantage of exist-
ing PM10 or TSP monitors, the need for additional monitors would be limited, which would
make the program less costly for U.S. EPA and the SLT entities.
B-20
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2. Is it appropriate to monitor for Pb-PMlO near Pb sources? And if so, under what conditions?
For large fugitive or stationary sources, TSP monitors capture all health-relevant Pb particles
and seem to be a better choice than PM10 monitors. Specifically, from Figure 2, Pb-PMlO
levels are about half of Pb-TSP levels.
3. One indicator option suggests using scaling Pb-PMlO monitoring data up to an equivalent
Pb-TSP level in lieu of Pb-TSP monitoring data. Under what circumstances would it be ap-
propriate to scale data (e.g., non-source oriented sites, low concentration sites) and when
would it not be appropriate to scale data?
From Figures 1 and 2, Pb-PMlO to Pb-TSP correlations seem relatively high, but further col-
located monitoring and analysis would strengthen the analysis.
4. We have limited collocated Pb-PM 10 and Pb-TSP monitoring data. What types and "scaling
factors" are appropriate to create using this data (e.g., non-source oriented, source ori-
ented)? What levels are appropriate for the types of scaling factors identified in the white
paper?
The data are limited and further collocated monitoring and analysis is needed, especially for
the source-oriented monitoring that has the highest Pb levels.
Attachment 2 - Draft Federal Reference Method (FRM) and Federal Equivalent Method
(FEM) Criteria for Lead in PM10 (Pb-PM 10)
1. Is it appropriate to use the low-volume PMlOcoarse FRM sampler as the Pb-PMlO FRM
sampler?
If the decision is to move away from total health risk (as represented by TSP) to inhalable
risk (PM10), then the use of the low-volume PMlOcoarse FRM sampler is reasonable.
2. What other PMIO samplers should be considered as either FRM or FEM for the Pb-PMlO
FRM?
SLT entities should be permitted to use the HiVol TSP and all existing FRM and FEM PMIO
samplers. Even if the Pb NAAQS goes from TSP to PMIO, TSP would be a conservative
(i.e., health-protective) measurement.
3. Is XRF an appropriate Pb-PM 10 FRM analysis method?
Yes. While it has problems with non-uniform deposits, XRF is a cost-effective technique.
4. What other analysis methods should be considered for FRM or FEM for the Pb-PM 10 FRM?
AAS, ICP/MS, and PIXIE.
B-21
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5. Have we selected appropriate precision, bias, and method detection limit requirements for
FEM evaluation ?
Yes. The current FEM requirements of 15% maximum precision and 5% accuracy seem rea-
sonable, as well as the proposed requirement that the MDL must be equal to or less than
1710th the level of the Pb NAAQS.
Attachment 3 - Lead NAAQS Ambient Air Monitoring Network: Network Design Options
Under Consideration
1. What types of monitoring sites should be emphasized in the network design (e.g., source ori-
ented monitors, population monitors, near roadway monitors) ?
Source oriented monitoring should be emphasized as these are the areas likely to have the
highest levels. If below the NAAQS, then no further monitoring is needed. Otherwise, popu-
lation and near roadway monitors should be considered.
2. We are considering proposing requirements for monitoring near sources exceeding an emis-
sions threshold and discuss a number of options for determining this threshold in the white
paper. What options should be considered in establishing an emissions threshold?
The analysis is reasonable, but the issue of periodically emitting sources should be consid-
ered, which would lower the emissions threshold.
3. We are considering proposing requirements for non-source oriented monitoring in large ur-
ban areas to provide additional information on ambient air concentrations in urban areas.
Considering other monitoring priorities and a potential requirement for Pb monitoring near
sources, what size of a non-source oriented Pb network is appropriate?
Non-source oriented monitoring should only be considered if analysis of existing data (e.g.,
Pb-TSP data, PM2.5 speciation Pb data, special study data, reconstructed Pb levels using air
quality modeling or interspecies correlations) show the potential to exceed the Pb NAAQS.
4. What factors should we base non-source oriented monitoring requirements on (e.g., popula-
tion, design value)?
It should only be based on the potential to exceed the Pb NAAQS.
5. We are considering proposing requirements for Pb monitoring near roadways and inter-
states. Is it appropriate to include separate monitoring requirements for near roadway moni-
toring, or should near roadway monitors be apart of the non-source oriented monitoring re-
quirement?
Unless the Pb NAAQS is very low, near roadway exposures should not be a problem, as
shown in Table 7.
B-22
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6. Under what conditions would it be appropriate to waive the monitoring requirements for ei-
ther source or non-source oriented monitors?
These conditions should be consistent with decisions for other criteria pollutants.
Attachment 4 - Lead NAAQS Ambient Air Monitoring Network: Sampling Frequency
Options Under Consideration
1. What sampling frequency would be appropriate if the Pb NAAQS is based on a monthly av-
erage?
The California Air Resources Board has had a monthly average Pb-TSP standard (not to be
exceeded) of 1.5 ug/m3 since 1970 and has always used one-in-six-day sampling. California
has always met a monthly 75% completeness criteria as compared to the federal requirement
of 75% across a quarter. One-in-three-day sampling should only be considered for sites that
are near or exceed the standard.
2. Is it appropriate to relax the sampling frequency in areas of low Pb concentration? If so, at
what per cent of the Pb NAAQS?
If a one-in-six-day sampling frequency is chosen, then no. If a one-in-three-day sampling is
selected, then the frequency should be relaxed if peak Pb levels are 30% or less of the
NAAQS, as proposed by U.S. EPA staff.
3. Is it appropriate to relax the sampling frequency in areas considerably higher than the
NAAQS? If so, at what percent of the Pb NAAQS?
No, as that would be unprecedented for criteria pollutant and not health protective for peri-
odic sources.
B-23
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Dr. Delbert Eatough
April 9, 2008
From: Delbert J. Eatough, CASAC AAMM subcommittee member
Subject: Review of Ambient Monitoring Issues Related to Lead
Options for Lead NAAQS Indicator: Monitoring Implications
As with others on the AAMM committee and in accord with the earlier statements of CASAC, I
fully support the elimination of TSP-Pb as an indicator of either total Pb exposure or the deter-
mination of ambient atmospheric exposure. I have delayed my comments until I had a chance to
review the 7-page memo describing the results of a November 1987 to April 1988 study con-
ducted by the State of Montana "Co-located PM-10/Hi-Vol Monitoring Results for E. Helena,"
dated July 22, 1988 which was provided to AAMM members yesterday by Fred Butterfield. My
comments will focus on that document and it's implications for some of the charge questions.
Specifically, I will address as a group the following charge questions.
Questions on Attachment 1 (Options for Lead NAAQS Indicator: Monitoring Implications)
Question 1: Considering issues such as sampler performance, size cuts, operator maintenance,
integration with other measurement systems, and usefulness as the measurement
system for the indicator, please describe the advantages and disadvantages of sam-
pling and analysis ofPb-TSP versus sampling and analysis ofPb-PMw.
Question 2: Is it appropriate to monitor for Pb-PMw near Pb sources? And if so, under what
conditions?
Question 3: One indicator option suggests using scaling Pb-PMw monitoring data up to an
equivalent Pb-TSP level in lieu ofPb-TSP monitoring data. Under what circumstances
would it be appropriate to scale data (e.g., non-source oriented sites, low concentration
sites) and when would it not be appropriate to scale data?
The advantages of using a Pb-PMio based monitoring system for the Pb ambient air qual-
ity standard lies in the greatly improved precision and better definition of what is being moni-
tored. In contrast, the old Pb-TSP sampling protocols are fraught with many uncertainties which
are well numerated in the material provided by EPA. The point however, has also been made
that it is total exposure that is important, especially for children. A comparison of results ob-
tained using these two monitoring methods was provided in Figures 1 and 2 of Attachment 1.
Figure 1, based on non-source oriented data suggests that no significant underestimation of am-
bient air Pb exposure will occur by changing the sampling method used to determine attainment.
However, Figure 2 suggests that significant under-determination of exposure can occur near ma-
jor Pb sources based on results from two studies. One of the studies (202090020, as identified in
Table 1) gives results which are within the range of the studies reported in Figure 1. The second
study, the above referenced E. Helena study suggests that exposure will be under-measured using
B-24
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the proposed Pb-PMi0 based protocol near a source by a factor of over 2. Since the driving force
for not changing the sampling protocols are essentially all contained in the results of this study,
the study deserves a closer look.
An examination of the document provided to the AAMM subcommittee by Fred
Butterfield on April 8 suggests this is a very weak hat to hang the whole decision of changing
from the Pb TSP measurement method or not. I have the following serious concerns with the
study:
1. The study does not carry the weight of a peer reviewed publication.
2. The samples were collected about /^ mile from the fence line of the ASARCO smelter.
At this distance, one would expect to see some variation in the mix of <10 and >10 mi-
cron particles present as a function of wind direction and wind speed as the import of
large particle fugitive dust versus small particle emissions impacts varies. In fact, this is
not the case, but the study is amazingly consistent for all collected data.
3. One would also expect to see a variation in the fraction of the particles present as Pb as
the above factors change the relative amount of various sources from the smelter. In fact,
this fraction is constant (as well as the ratio of PMi0 and TSP) for all data points.
4. No details are given on the filter media on which samples were collected, the methods of
data analysis, blank corrections, etc.
In short, the study is not consistent with know and expected variations in large versus small par-
ticle concentrations and composition from a near-by smelter source. In addition, insufficient de-
tail is given to determine whether this unexpected result is due to a most fortuitous combination
of meteorological factors, or to a fundamental flaw in the study design and sample analysis. I
therefore conclude that established something as important as the direction of the future Pb stan-
dard and the associated sampling protocol essentially on this study is folly. Outside this result
there is no credible data which have presented in the EPA attachment which would argue that
exposure to children can be significantly under measured if the Pb TSP method is abandoned.
Based on the above, I strongly support moving to a Pb-PMio protocol. Furthermore, I
believe attempting to use factors in setting the standard would not be based on firm data. If it is
believed that the TSP standard should be maintained, I would think additional data are needed to
justify such a decision. Neither cost nor the current science justifies it in my opinion.
B-25
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Mr. Dirk Felton
Dirk Felton: CASAC AAMM Individual Written Comments on
Ambient Air Monitoring Options for Lead
(Prepared for the March 25th teleconference
Revised March 27th)
These comments have been made in spite of the broad range proposed for the primary and
secondary Pb NAAQS. The level of the standard drives much of the network design, sam-
pler technical specifications and analytical methods. More specific comments can be of-
fered if the range for the standard is narrowed.
Part of the discussion during the teleconference centered around the desire to know the size
of the Pb containing particles in ambient air. The NYSDEC has some Pb size data avail-
able from a PMcoarse evaluation that was performed in 2005. Samples were collected
through calendar year 2005 on the EPA 1 in 6 day schedule. Filters were analyzed by XRF
from low volume PMu and PM2s samplers in New York City and Niagara Falls, NY. The
data for Pb is displayed in table 1 as ratios of PMio / PMcoarse.
Table 1
NYC
mean
median
25%ile
75%ile
min
max
All Data Cold Months Warm Months
0.47
0.47
0.29
0.66
0.00
1.00
0.41
0.43
0.23
0.61
0.00
0.93
0.53
0.61
0.33
0.71
0.00
1.00
Nia Falls
mean
median
25%ile
75%ile
min
max
All Data Cold Months Warm Months
0.31
0.27
0.08
0.47
0.00
1.00
0.27
0.29
0.06
0.46
0.00
0.58
0.34
0.24
0.12
0.53
0.00
1.00
The data shows that for the Pb containing particles smaller than PMio, slightly more Pb is
found in the PMi.s fraction than in the PMc fraction at these locations in New York.
A presentation on the NYSDEC PMc evaluation was delivered at the 2006 National Moni-
toring Conference. The .ppt file can be found on the EPA AMTIC webpage:
^
B-26
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Attachment 1 Options for LeadNAAQS Indicator: Monitoring Implications
Charge Questions:
1. Considering issues such as sampler performance, size cuts, operator maintenance, inte-
gration with other measurement systems, and usefulness as the measurement system for the
indicator, please describe the advantages and disadvantages of sampling and analysis ofPb-
TSP versus sampling and analysis ofPb-PMio.
The primary advantage of implementing the PMi0 size cut for the Pb standard is
that the resulting data is more relevant for air pollution related health effect
correlation and for source permitting and source control.
2. Is it appropriate to monitor for Pb-PMw near Pb sources? And if so, under what conditions?
It depends on the type of source. TSP is still the best choice for monitoring on-site
and at the perimeter of large fugitive Pb sources. This would include primary smelt-
ers and other smaller sources where significant outdoor raw material handling is
performed. It is acceptable to use PMio monitors at middle or neighborhood scale
population exposure locations adjacent to source properties. The data from the
PMio monitors is more consistent because in locations downwind of Pb sources, the
data will be relatively unaffected by deposition losses. This makes the interpretation
of data simpler because varying downwind concentrations can be more easily re-
lated to sources.
3. One indicator option suggests using scaling Pb-PMw monitoring data up to an equivalent
Pb-TSP level in lieu ofPb-TSP monitoring data. Under what circumstances would it be ap-
propriate to scale data (e.g., non-source oriented sites, low concentration sites) and when
would it not be appropriate to scale data?
Scaling PMio data is not necessary. Sites that are distant from sources of Pb are not
going to be significantly impacted by particles larger than PMio. One way to deter-
mine if a monitoring location is likely to be impacted by large particles is to review
the historical variation of the Pb TSP data. Since concentrations of large particles
vary tremendously due to source variations such as work shift changes, material
handling changes, deposition, and meteorology; datasets that exhibit little concen-
tration variation are not likely to be impacted by large particles. (See the upwind
site data in Figurel.)
B-27
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(Figure 1)
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Downwind 1 Downwind 2 Upwind
Attachment 2 Draft Federal Reference Method (FRM) and Federal Equivalent Method
(FEM) Criteria for Lead in PM10 (Pb- PM^
Charge Questions:
1. Is it appropriate to use the low-volume PMw FRM sampler as the Pb-PMw FRM sampler?
Yes, the sampler is well characterized and very familiar to State and Local air moni-
toring Agencies. The sequential versions of the samplers should also be designated
as FRMs because future Pb PMu FEM evaluations should use the FRM samplers
and protocols most predominantly utilized in the National network. Future FEM
evaluations should be designed with the identical sample collection interval (mid-
night to midnight) and filter handling procedures as followed by the majority of the
data providers for the national network.
2. What other PMw samplers should be considered as either FRM or FEM for the Pb-PMw
FRM?
Monitoring Agencies should be permitted to use High Volume TSP and existing
High Volume FRM and FEM PM10 samplers if the data is approximately adjusted
for Local Conditions and the data from the site is well below the ambient Pb stan-
dard (< 70% of the NAAQS). If TSP samplers are used, the resulting Pb concen-
trations should be compared to a new Pb-PM10 standard. High Volume samplers
would have to be considered FEMs.
3. Is XRF an appropriate Pb-PMw FRM analysis method?
Specifying XRF would make analytical problems stemming from non-uniform load-
ing and non-ideal filter loading densities an inherent part of the FRM. ICPMS
B-28
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should be the analysis method for the FRM and for the PEP audit samples. ICPMS
is more accurate and it does not require the filter to be uniformly loaded. XRF
should be designated as a cost effective FEM that is routinely compared to ICPMS
through the periodic collocation of the PEP audit program.
4. What other analysis methods should be considered for FRM or FEM for the Pb-PMw FRM?
XRF and GFAA should be considered for FEM designation.
5. Have we selected appropriate precision, bias, and method detection limit requirements for
FEM evaluation ?
The precision requirement should be tightened to 10% for new methods with a
provision for 15% to permit FEM designation for existing high volume samplers.
Attachment 3 LeadNAAQS Ambient Air Monitoring Network: Network Design Options
Under Consideration
Charge Questions:
1. What types of monitoring sites should be emphasized in the network design (e.g., source
oriented monitors, population monitors, near roadway monitors)?
Source oriented monitoring should be emphasized.
2. We are considering proposing requirements for monitoring near sources exceeding an
emissions threshold and discuss a number of options for determining this threshold in the
white paper. What options should be considered in establishing an emissions threshold?
The analyses described in the white paper look at the amount of Pb emitted from a
facility but there is no consideration of the type of emissions. Sources that handle
large quantities of raw materials such as smelters and battery recyclers are likely to
emit large plumes periodically. These sources will need downwind monitoring at a
lower threshold than a source such as a ceramic manufacturer or a municipal incin-
erator that has a more consistent process output. The emissions threshold should be
a range that provides for more intensive monitoring for sources that have relatively
high Pb emissions or for sources that have the ability to release high concentrations
of Pb if a process control were to malfunction.
3. We are considering proposing requirements for non-source oriented monitoring in large ur-
ban areas to provide additional information on ambient air concentrations in urban areas. Con-
sidering other monitoring priorities and a potential requirement for Pb monitoring near sources,
what size of a non-source oriented Pb network is appropriate?
Urban areas are likely to show a small increment to the background Pb concentra-
tions associated with known sources. Since these increments are not significant at
B-29
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all but the lowest concentrations under consideration for the revised NAAQS, non-
source oriented monitoring should not be emphasized in urban areas distant from
Pb sources. Historic Pb data and current data from the NATTs network locations
can be used to determine if urban areas are close enough to a source to warrant am-
bient monitoring. Figure 2 shows the Pb concentrations for an urban location in
New York City and a regional site in the Hudson Valley.
(Figure 2)
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* New York City « Hudson Valley
4. What factors should we base non-source oriented monitoring requirements on (e.g.,
population, design value) ?
Population size is not well correlated with ambient Pb concentration and should not
be used as a factor in Pb ambient monitoring network design. The design value is
acceptable if one can be calculated from historical data or from data collected by
other monitoring programs such as NATTs.
Urban areas are also sometimes located near known sources of Pb. In these cases,
population exposure monitors are warranted in order to obtain a reasonable design
value for the urban/populated area. These evaluation monitors should be easily dis-
continued if they demonstrate that the newly calculated design value is below 35%
of the NAAQS.
5. We are considering proposing requirements for Pb monitoring near roadways and inter-
states. Is it appropriate to include separate monitoring requirements for near roadway
monitoring, or should near roadway monitors be apart of the non-source oriented moni-
toring requirement?
Near roadway monitors will only be necessary if the NAAQS is chosen at the lowest
of the levels currently under consideration. If the Pb NAAQS is set at a very low
level, near roadway monitors should be considered source monitors. This may aid
B-30
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in the development of emission factors for specific roadway attributes such as age,
vehicle miles traveled and the ratio of heavy duty diesels to passenger cars.
6. Under what conditions would it be appropriate to waive the monitoring requirements for
either source or non-source oriented monitors?
Source oriented monitoring could be waived if the source conducts routine super-
vised representative Pb monitoring and that monitoring data shows no short term
concentration spikes and no incremental differences in the downwind Pb concen-
tration.
Required non-source oriented monitors should be waived if the design value is be-
low 35% of the NAAQS and there are no changes in the inventory of potentially
significant sources. The non-source oriented sites that have design values below
70% of the NAAQS should be permitted to reduce their monitoring frequency to
50% of the required sampling frequency.
Single monitors can be assigned for non-source oriented population exposure moni-
toring as long as the design value is below 70% of the NAAQS. If the design value
of the MSA/CBSA is greater than 70% of the NAAQS, multiple monitors may be
required in order to accurately determine the possible extent of a non-attainment
area.
Attachment 4 Lead NAAQS Ambient Air Monitoring Network: Sampling Frequency
Options Under Consideration
Charge Questions:
1. What sampling frequency would be appropriate if the Pb NAAQS is based on a monthly
average?
One day in three represents a reasonable compromise between necessary accuracy
and the effort and costs required to perform frequent filter based sample collection
and chemical analysis.
2. Is it appropriate to relax the sampling frequency in areas of low Pb concentration? If so, at
what percent of the Pb NAAQS?
Yes, the sampling frequency should be reduced by 50% when the design value is be-
low 70% of the NAAQS. The sampling frequency should also be reduced when the
ambient data is very consistent from sample to sample. This could be instituted by
specifying a threshold coefficient of variation below which the sampling frequency
could be reduced. The sampling frequency should not be reduced for sites near large
sources.
B-31
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3. Is it appropriate to relax the sampling frequency in areas considerably higher than the
NAAQS? If so, at what percent of the Pb NAAQS?
No, Pb concentration data from areas above the NAAQS are necessary to ade-
quately determine the potential health effects from specific Pb sources.
B-32
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Dr. Philip Hopke
Comments by Philip K. Hopke on Pb Monitoring Issues
The documents provided for review were well written and provided reasonable approaches to the
monitoring issues. However, there needs to be a clearer tie between the exposure pathways and
the monitoring approaches. It seems incongruous that if we believe a wide range of particle sizes
are important, we then only measure a fraction of the particles when it might be possible to ob-
tain a measure of a wider size range of particles. There is not yet a clear enough definition of the
exposure pathways and using those definitions to provide the basis for why, where and how
monitoring should be done to produce data relevant to protect the public health. In the case of
lead, there is a clearly defined susceptible subpopulation, children, and the design of the monitor-
ing program needs to address this issue. Exposure to the population as a whole is much less im-
portant than exposure of children to lead and thus, monitoring must be targeted in those areas
most likely to produce exposure to children.
Considering issues such as sampler performance, size cuts, operator maintenance, integration
with other measurement systems, and usefulness as the measurement system for the indicator,
what are the advantages and disadvantages of sampling and analysis ofPb-TSP versus sampling
and analysis ofPb-PMw?
The main advantage I can see is that the PM10 would provide lower costs and ease of implemen-
tation. However, if there is real concern that large particle coarse particles are of concern, then it
makes more sense to measure TSP. It is possible to measure TSP with much greater precision
than is currently possible with the high volume sampler. One wants samplers that has good flow
control, no wind speed and direction dependence and provides a filter that is appropriate for the
analytical method of choice. It is certainly possible to do this with currently available technol-
ogy that provides good flow control and insensitivity to wind direction. There remains a prob-
lem with wind speed, but I would suggest that this is of relatively limited concern since there
would still be good sampler to sampler precision. Thus, I would suggest against switching to
PM10 as the inlet since I think it is better to try to directly measure the indicator rather than a
surrogate and guess at how to "correct" the result to provide an indirect measure of the indicator.
You should look at Kenny L, Beaumont G, Gudmundsson A, Thorpe A, Koch W Source:
JOURNAL OF ENVIRONMENTAL MONITORING Volume: 7 Issue: 5 Pages: 481-487
Published: 2005
Is it appropriate to monitor for Pb-PMw near Pb sources? And if so, under what conditions?
Only if you are going to a PMlO-based standard. If TSP is of concern, then TSP is what should
be measured as well as it possibly can be measured.
One indicator option suggests scaling Pb- PM10 monitoring data up to an equivalent Pb-TSP
level in lieu of Pb-TSP monitoring data. Under what circumstances would it be appropriate to
scale data (e.g., non-source oriented sites, low concentration sites) and when would it not be
appropriate to scale data?
B-33
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It is always risky to "scale" data when it is possible to directly measure a quantity of interest.
We have limited collocatedPb-PMw andPb-TSP monitoring data. What types and "scaling
factors" are appropriate to create using this data (e.g., non-source oriented, source ori-
ented)? What levels are appropriate for the types of scaling factors identified in the white pa-
per?
If we set a stringent standard level, then the values will be so dominated by noise and the de-
velopment of a scaling factor is then quite uncertain. Thus, I still believe it is best to monitor
that which we think is the cause of the adverse health effects.
Is it appropriate to use the low-volume PMlOc FRM sampler as the Pb-PM10 FRM sampler?
What other PM]0 samplers should be considered as either FRM or FEMfor the Pb-PMw
FRM?
Sure. The PMlOc sampler provides good precision for mass collection and thus, will provide
good precision for Pb in PM10. The current FEM rules for the PM10 head are quite lax be-
cause the acceptance interval was made too wide in 1987. If you want FEM precision to be
good, the acceptance window for the PM10 inlet performance should be reduced from + 0.5 jim
at 10 |im to something more like + 0.1 to 0.2 |im. Then FEMs would have good precision in
side-by-side comparisons with the PMlOc sampler.
Is XRF an appropriate Pb-PMw FRM analysis method?
Yes, there can be problems in areas with significant As concentrations since there is an overlap
in the As Ka with one of the Pb 1-lines.
What other analysis methods should be considered for FRM or FEMfor the Pb-PMw FRM?
ICP/MS or GFAAS would both provide the sensitivity and precision. Electrochemical meth-
ods like anodic stripping voltammetry can be useful and should be considered.
Have we recommended appropriate precision, bias, and method detection limit requirements
for FEM evaluation ?
Yes
What types of monitoring sites should be emphasized in the network design (e.g., source oriented
monitors, population monitors, near roadway monitors)?
What are the exposure pathways that are being looked at to provide protection to the public?
The key is whether lead is being transported to playgrounds, urban gardens, etc where ingestion
hazards might become important. Is the primary monitoring interest in population exposure,
source identification and assessment, etc.? If it is population exposure, then the source areas
are of less importance to monitor. Near minor roadways where children might play would be
significant locations at which to make measurements.
B-34
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We are considering proposing requirements for monitoring near sources exceeding an emissions
threshold and discuss a number of options for determining this threshold in the white paper.
What options should be considered in establishing an emissions threshold?
Emissions thresholds in what sizes? Ultra coarse particles will not be transported at significant
distances whereas PM10 and smaller can be transported over sufficient distances to be important.
Again, there is no simple answer here in the absence of a clearer definition of why the measure-
ments are being made.
We are considering proposing requirements for non-source oriented monitoring in large urban
areas to provide additional information on ambient air concentrations in urban areas. Consid-
ering other monitoring priorities and a potential requirement for Pb monitoring near sources,
what size of a non-source oriented Pb network is appropriate?
The question here is how much ultra-coarse is likely to be present and how uniform or non-
uniform are the sources of these larger particles. More heterogeneous source locations lead to
the need for more samplers. One suggestion would be to make some measurements using the
Leith and Wagner passive monitor where they are sufficient low cost that many samples could be
obtained across an urban area and the variability assessed. One could even consider a require-
ment to make an initial assessment of the heterogeneity of exposures with low cost sampling and
use those results to plan an effective monitoring network tailored to the individual urban area
rather than a one size fits all philosophy.
What factors should we base non-source oriented monitoring requirements on (e.g., population,
design value) ?
The design needs to include both the inhalation risk and the ingestion risk. The target population
has to be children over adults and thus, areas where there could be significant exposure like
schools, playgrounds, ball parks, etc. should be a priority. If there are designated urban garden
areas, then they should also be target areas. The key is that adults are not as affected by lead as
children so the population at risk should drive the location plans.
We are considering proposing requirements for Pb monitoring near roadways and inter states. Is
it appropriate to include separate monitoring requirements for near roadway monitoring, or
should near roadway monitors be apart of the non-source oriented monitoring requirement?
Under what conditions would it be appropriate to waive the monitoring requirements for either
source or non-source oriented monitors?
What sampling frequency would be appropriate if the Pb NAAQS is based on a monthly aver-
age?
You need enough points to provide a meaningful average. At 1 in 6 sampling, we would only
have 5 points per month and that would provide a measurement with lower power and a higher
probability of type 1 errors than a 1 in 3 schedule. I would suggest that 1 in 3 would need to be
required.
B-35
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Is it appropriate to relax the sampling frequency in areas of low Pb concentration? If so, at
what percent of the Pb NAAQS?
Once there is a good data base to support the attainment with low risk exists, it is certainly possi-
ble to relax the sampling schedule unless some new facility is built that has the potential for lead
emissions. There would need to be a trigger to increase sampling if there is significant new de-
velopment in the area.
Is it appropriate to relax the sampling frequency in areas considerably higher than the NAAQS?
If so, at what percent of the Pb NAAQS?
Shouldn't the local agency want high confidence data on the lead concentrations if they are in
non-attainment and there is a SIP in place to force reductions. This question does not make a lot
of sense to me since if the area is in substantial non-attainment, one would have thought there
would be action on-going to reduce the concentrations and thus, a desire to assess the improve-
ments being made. Thus, I cannot see any reason why one would want to reduce the measure-
ment frequency.
B-36
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Dr. Rudolf Husar
March 27, 2008
To: Fred Butterfield, Designated Federal Officer, Clean Air Scientific Advisory Committee
(CASAC); Ted Russell, CASAC Ambient Air Monitoring and Methods (AAMM) Subcommittee
Chair
From: Rudolf B. Husar, CASAC AAMM subcommittee member
Subject: Review of Ambient Monitoring Issues Related to Lead
Options for Lead NAAQS Indicator: Monitoring Implications
I fully support the elimination of TSP-Pb as an indicator of total Pb exposure. The use of coarse
particle (PM2.5-PM10) Pb or PM10 Pb is appropriate for estimating the ambient Pb concentra-
tions. If indeed, most of the Pb exposure (of children) is due to the ingestion of soil material,
then the relevant indicator should be the Pb in the soil, which may have vary poor relationship to
the ambient Pb concentration in any size range.
Lead NAAQS Ambient Air Monitoring Network: Network Design Options Under
Consideration
The section of the document describing the network design is well prepared and presented. The
separation of source, population and roadway-oriented monitors is logical and well-suited as
network design and implementation criteria. The emphasis of the Pb monitoring network should
be placed on source monitoring since point sources now dominate the national emissions. Using
the source emission rate as a sealer for the number of source-oriented monitoring sites makes
sense. An alternative metric for scaling the number of monitors is the population-weighed expo-
sure. This would require more monitors for those sources that result in higher population expo-
sure.
Population-oriented monitors would require more consideration. In particular, it would be help-
ful to establish whether most of the population exposure is from known distant point sources or
from less known local sources. In case of the latter, a strategically designed moving sampler
would establish whether such unknown Pb sources exist.
I also support Donna Kenski's suggestion to make maximum utilization of the monitoring data
from the Speciation Trends Network and the evolving NCore. I do not see any reason why the
Pb-sampling frequency should be different from the STN/NCor networks.
B-37
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Dr. Kazuhiko Ito
Comments for the March 25, 2008 Clean Air Scientific Advisory Committee (CASAC)
Ambient Air Monitoring & Methods (AAMM) Subcommittee Teleconference
Kazuhiko Ito, 3/21/08
General comment: The range of "candidate NAAQS level" shown in these tables (0.02 to the
current 1.5 |ig/m3) is quite wide (I understand that the Staff Paper recommends no higher than
0.2 |ig/m3). It may be important to compare the extent of uncertainty associated with the re-
ported exposure/health effects relationships and the estimated uncertainty associated with Pb
monitoring network design.
"Options for Lead NAAQS Indicator: Monitoring Implications"
Ql. Considering issues such as sampler performance, size cuts, operator maintenance, integra-
tion with other measurement systems, and usefulness as the measurement system for the indica-
tor, please describe the advantages and disadvantages of sampling and analysis ofPb-TSP ver-
sus sampling and analysis ofPb-PMw.
Advantages: The better precision and ability to accommodate sequential sampling in case more
frequent sampling (i.e., every 3rd day) is required.
Disadvantages: Possible requirement for "scaling factor" to adjust for larger particles that the
Pb-PMio sampler may miss.
Q2. Is it appropriate to monitor for Pb-PMionear Pb sources? And if so, under what conditions?
Figure 2 on page 7 indicates a good linear relationship. This suggests that Pb-PMio works in
source-oriented situations, but I think more data (pilot studies?) are needed to more fully charac-
terize the factors (e.g., size distribution, wind-direction dependency, etc.) that affect comparabil-
ity between Pb-TSP and Pb-PMi0 samplers.
Q3. One indicator option suggests using scaling Pb-PMio monitor ing data up to an equivalent
Pb-TSP level in lieu of Pb-TSP monitoring data. Under what circumstances would it be appro-
priate to scale data (e.g., non-source oriented sites, low concentration sites) and when would it
not be appropriate to scale data?
The source oriented sites' data (Figure 2) support justification for scaling factor using the rela-
tively good relationship. It is more difficult to tell what we should do for non-source monitoring
unless we look at the data for any pattern by city, region, or period. I feel a bit uncomfortable
using scaling factors based on data such as those shown in Figure 1. In Figure 1, it is not clear
how much of the scatter is due to the imprecision of TSP. As I mentioned in the conference call,
I think it would help if we can see the scatter plots of co-located Pb-TSP monitors and co-located
Pb-PMio monitors.
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Regarding Figure 2, since the data came from 1200 data pairs from 31 non source-oriented sites
that collected data between the years 1993 and 2006,1 imagine that the overall regression could
be masking potentially important information such as variation in slope across sites, regions, and
years. During the conference call, Mr. Kevin Cavender mentioned that the slope of individual
sites varied between 1 and 1.4, which made me feel more comfortable, but I would still consider
running a regression model that takes into consideration the fact that the data came from differ-
ent sites (mixed effects model).
"Draft Federal Reference Method (FRM) and Federal Equivalent Method (FEM) Criteria
for Lead in PM10 (Pb- PM10)"
Ql. Is it appropriate to use the low-volume PMwc FRM sampler as the Pb-PMio FRM sampler?
It seems reasonable given the better precision than the Pb-TSP sampler.
Q2. What other PMw samplers should be considered as either FRM or FEM for the Pb-
PMwFRM?
I don't know.
Q3. Is XRF an appropriate Pb-PMio FRM analysis method?
It sounds reasonable based on the required characteristics. It is also comparable with the PM2 5
and PMc speciation monitor data. During the conference call, Dr. Phil Hopke mentioned possi-
bility of As-Pb spectral interference. I think the EPA can check how much of a problem this is by
analyzing available data from various source types.
Q4. What other analysis methods should be considered for FRM or FEM for the Pb-PMio
FRM?
I don't know.
Q5. Have we selected appropriate precision, bias, and method detection limit requirements for
FEM evaluation ?
Given the expected concentration range and the possible range of Pb NAAQS, the requirements
seem appropriate.
"Lead NAAQS Ambient Air Monitoring Network: Network Design Options Under Con-
sideration"
Ql. What types of monitoring sites should be emphasized in the network design (e.g., source ori-
ented monitors, population monitors, near roadway monitors) ?
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I get a mixed impression about the relative importance of source types from these documents.
The statement on page 1, ".. .there is substantial uncertainty about ambient air Pb levels resulting
from historic Pb deposits near roadways," suggests that, at least initially, we need near-roadway
monitors. However, Table 7 (page 8) suggests that the Pb levels near roadways are not that high,
though we don't have much data on this table.
In cities where densities of roadways are high, what is the distinction between "non-source ori-
ented monitoring" and "near roadway monitoring"? Also, during the conference call, the issue
of aviation gasoline being an important source came up. I imagine most airports are also sur-
rounded with major roadways. Thus, many of the major city neighborhoods may be difficult to
characterize as "non-source".
Source-oriented monitors are clearly important when populations living nearby are at risk, but it
seems we do need more data to characterize spatial variation of Pb in "near roadway" and "non-
source" areas. I found that the rational to emphasize ozone and PM2.5 monitors in comparison to
Pb a bit unconvincing - the levels of ozone and PM2 5 would be fairly uniform within a city be-
cause they are secondary formed pollutants. One can argue that we need more monitors for the
pollutants that are spatially more variable because they are locally generated.
Q2. We are considering proposing requirements for monitoring near sources exceeding an emis-
sions threshold and discuss a number of options for determining this threshold in the white pa-
per. What options should be considered in establishing an emissions threshold?
This idea of using the ratio of the observed Pb levels to the emission rate to come up with an
emission threshold seems reasonable. The tables prepared in this document are very useful in
supporting this idea. The only obvious issue we see with this approach is that, when we get to
Table 5 (page 6), it becomes clear that we may need to monitor at a large number of locations (>
1,000) if the Pb NAAQS is set at 0.2 |ig/m3 or less. Given the range of variability in the concen-
tration-to-emission ratios (Table 2), an initial site-specific surveillance may be required to de-
termine if monitoring is needed in that location.
Q3. We are considering proposing requirements for non-source oriented monitoring in large ur-
ban areas to provide additional information on ambient air concentrations in urban areas. Con-
sidering other monitoring priorities and a potential requirement for Pb monitoring near sources,
what size of a non-source oriented Pb network is appropriate?
It is difficult to figure out how many monitors we need unless we know the extent of spatial
variation of Pb. We need some kind of pilot study to characterize the spatial variation.
Q4. What factors should we base non-source oriented monitor ing requirements on (e.g., popula-
tion, design value) ?
(1) Population size; (2) existing data indicating Pb concentrations higher than "background" lev-
els.
Q5. We are considering proposing requirements for Pb monitoring near roadways and inter-
B-40
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states. Is it appropriate to include separate monitoring requirements for near roadway monitor-
ing, or should near roadway monitors be apart of the non-source oriented monitoring require-
ment?
Given the high density of roadways in many urban areas, I think there is no need to separate
sampling requirements for these two monitoring types.
Q6. Under what conditions would it be appropriate to waive the monitoring requirements for
either source or non-source oriented monitors?
(1) no population being impacted; (2) existing or initial monitoring suggests sufficiently low am-
bient Pb concentrations.
"Lead NAAQS Ambient Air Monitoring Network: Sampling Frequency Options Under
Consideration"
Ql. What sampling frequency would be appropriate if the Pb NAAQS is based on a monthly av-
erage?
Every-3rd-day sampling appears appropriate if the Pb-PMi0 low flow sampler is going to be used.
I would also find out, from a pilot study, if this sampling frequency satisfies DQO. In addition, I
would take the every-6th-day part of the every-3rd-day data in pilot study and check if the preci-
sion is sufficient for DQO. If it is, then allow the sampling frequency to be every-6th-day.
Q2. Is it appropriate to relax the sampling frequency in areas of low Pb concentration? If so, at
what percent of the Pb NAAQS?
Again, this depends on the precision of the data and DQO.
Q3. Is it appropriate to relax the sampling frequency in areas considerably higher than the
NAAQS? If so, at what percent of the Pb NAAQS?
It is hard to comment on this without actually looking at data.
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Dr. Donna Kenski
Revised Preliminary Comments on Pb NAAQS Monitoring
Donna Kenski
For AAMM Consultation March 25, 2008
1. Charge questions, attachment 1, Options for Lead NAAQS Indicator: Monitoring Implica-
tions: Considering issues such as sampler performance, size cuts, operator maintenance, in-
tegration with other measurement systems, and usefulness as the measurement system for the
indicator, please describe the advantages and disadvantages of sampling and analysis ofPb-
TSP versus sampling and analysis ofPb-PMlO.
As I commented in reviewing the Lead ANPR, I prefer changing the Pb NAAQS indicator to Pb-
PM10. This option takes advantage of current technology to make a more precise measurement,
it would allow states to make better use of existing monitors, and the technology allows sequen-
tial measurements to be made automatically. While it will not capture the fraction of Pb on very
large (>10 um) particles, I believe that it is possible to account for this in a reasonable way by
incorporating a scaling factor into the standard. The uncertainty or variability introduced with
this scaling factor is probably not significantly greater than that introduced by the TSP monitor
itself, by virtue of its varying size cut with wind speed and direction.
Is it appropriate to monitor for Pb-PMlO near Pb sources? And if so, under what conditions?
Yes, it is appropriate to monitor for Pb-PMlO near Pb sources. Elevated Pb will show up in
PM10 if it shows up in TSP. I can't imagine a scenario where TSP could show levels of Pb at or
near the standard and PM10 would not. As noted above, incorporating a scaling factor into the
standard would provide an adequate margin of safety to account for possible PM-Pb distributions
that were skewed toward the >10 um particles.
One indicator option suggests using scaling Pb-PM 10 monitoring data up to an equivalent Pb-
TSP level in lieu ofPb-TSP monitoring data. Under what circumstances would it be appropriate
to scale data (e.g., non-source oriented sites, low concentration sites) and when would it not be
appropriate to scale data?
I don't think the data should be scaled, I think the standard should be set for Pb-PMlO at a level
that is sufficiently protective of human health to account for possible ultra-coarse particles not
collected by the sampler. That is, the scaling factor should be built into a PM10 standard, not
applied to adjust PM10 data for comparison with a TSP standard. While I would prefer to see
additional data on Pb-PMlOPb-TSP relationships, I think EPA has sufficient information at
the moment to make a reasonable estimate of that relationship, as shown in the memorandum
from Kevin Cavender.
We have limited data collocated Pb-P 10 and Pb-TSP monitoring data. What types and
"scalingfactors" are appropriate to create using this data (e.g., non-source oriented, source
oriented) ? What levels are appropriate for the types of scaling factors identified in the white pa-
per?
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It would be helpful to see the Pb-PMlOPb-TSP relationship for a variety of sources and moni-
tor sites - smelters, mines, roadways, other industrial sites, etc. However, I know this type of
data is very limited. If time permits, EPA might attempt to collect additional data to better char-
acterize the relationship.
2. Charge questions, attachment 2, Draft FRM and FEM criteria (memo from Joann Rice):
Is it appropriate to use the low-volume PM10 FRM sampler as the Pb-PMlO FRM sampler?
Yes.
What other PM10 samplers should be considered as either FRM or FEM for the Pb-PMlO
FRM?
EPA should consider allowing TSP monitors to be compared to the Pb-PMlO NAAQS when
(unadjusted) values are below the new Pb-PMlO standard. This would be conservative - con-
centrations from the TSP would be biased high relative to PM10 - and would allow the
states/locals some flexibility in turnover to the newer technology.
Is XRF an appropriate Pb-PMlO FRM analysis method?
Yes, it improves the detection limit and has acceptable costs and thus should be permitted. The
fact that it is nondestructive is a bonus.
Have we selected appropriate precision, bias, and method detection limit requirements for FEM
evaluation?
All the proposed changes to the FRM and FEM criteria were reasonable.
3. Charge questions, attachment 3, Ambient Monitoring Network: What types of monitoring
sites should be emphasized in the network design (e.g., source oriented monitors, population
monitors, near roadway monitors)?
Concentrations near sources are elevated so the initial focus should be there; the requirements for
which sources, based on emission limits, will clearly depend on the level of the standard. The
roadway data are pretty limited and I'm not sure we have adequate information to make a deter-
mination yet about the extent of monitoring needed there; this will also depend strongly on the
level of the new standard. Population monitors seem the least critical. Presumably the NCore
network will be making Pb-PMlO measurements; can those be designated as the Pb population
monitors as well?
We are considering proposing requirements for monitoring near sources exceeding an emissions
threshold and discuss a number of options for determining this threshold in the white paper.
What options should be considered in establishing an emissions threshold?
We are considering proposing requirements for non-source oriented monitoring in large urban
areas to provide additional information on ambient air concentrations in urban areas. Consider-
ing other monitoring priorities and a potential requirement for Pb monitoring near sources,
what size of a non-source oriented Pb network is appropriate?
What factors should we base non-source oriented monitoring requirements on (e.g., population,
design value) ?
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I don't think non-source oriented monitoring needs to be a priority for this pollutant. It is clear
that near-source exposures are the ones that are most relevant. I'd be content with measurements
from NCore, if all -75 sites make speciated PM10 measurements. Between these measurements
and the PM2.5 speciation network, there would be a respectable national data set to assess typi-
cal non-source concentrations in urban and rural environments.
We are considering proposing requirements for Pb monitoring near roadways and inter states. Is
it appropriate to include separate monitoring requirements for near roadway monitoring, or
should near roadway monitors be apart of the non-source oriented monitoring requirement?
I haven't seen enough data on how Pb varies with roadway type, traffic counts, or other factors
to make a recommendation on this. I really think we need to collect more data before making
this a requirement.
Under what conditions would it be appropriate to waive the monitoring requirements for either
source or non-source oriented monitors?
If several years of monitoring data (PM-10 or TSP) demonstrate compliance or if a comprehen-
sive modeling analysis for a source shows no potential for exceedances. However, it seems like
some kind of maintenance monitoring should be required for sources that have the potential for
exceedances, even if their monitoring data show compliance for a particular period.
4. Charge questions, attachment 4: Sampling Frequency Options:
What sampling frequency would be appropriate if the Pb NAAQS is based on a monthly aver-
age?
Is it appropriate to relax the sampling frequency in areas of low Pb concentration? If so, at what
percent of the Pb NAAQS?
Is it appropriate to relax the sampling frequency in areas considerably higher than the
NAAQS? If so, at what percent of the Pb NAAQS?
I'm not totally convinced that monthly averages are a necessity, but if the averaging time does
change to 1 month, then the sampling frequency does need to increase to 1/3 day. As above, if
monitors show attainment with the standard it is definitely reasonable to relax the frequency re-
quirement. The 30% figure proposed was fine. I'm not sure I see the rationale to relaxing fre-
quency in areas above the NAAQS. Presumably there will be actions taken to reduce concentra-
tions, which we would want to document with measured values, and particularly with improved
precision as we approach the standard.
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Dr. Armistead (Ted) Russell
CASAC AAMM Ambient Air Lead Monitoring Lead
Armistead Russell
(Prepared for the March 25th teleconference)
While generally supportive of using PM10 monitoring for lead, as opposed to TSP, this
is particularly true if a tighter standard is chosen. The relative benefits of going to a PM10 moni-
tor, and issues with TSP monitors, were well laid out by CASAC in their letters regarding the
NAAQS lead standard, so they will not be repeated here, except to say that a tighter standard is
less near-source oriented than our current one, suggesting a finer cut point. Further, the data do
not suggest that there will be a significant different between the two in most cases that, along
with a tighter standard, would suggest that using PM10 would not be protective of public health
and also provide more and more usable data, further helping to protect public health. My major
concern is that the TSP monitoring is becoming significantly less extensive with time, and there
are areas with major sources that are not monitored.
Options for Lead NAA OS Indicator: Monitoring Implications
1. Considering issues such as sampler performance, size cuts, operator maintenance, in-
tegration with other measurement systems, and usefulness as the measurement system for the in-
dicator, please describe the advantages and disadvantages of sampling and analysis ofPb-TSP
versus sampling and analysis ofPb-PMw.
Primary advantages of PM10 monitors include that they are less subject to sampling
variability (e.g., size cuts, etc.), the PM being measured is more relevant to area-wide exposures
and that there is a broader coverage with the PM10 monitors.
2. Is it appropriate to monitor for Pb-PMw near Pb sources? And if so, under what con-
ditions?
Yes. While TSP monitors will pick up higher levels on, or near the fence line of large
sources that emit larger sized lead-containing particles, the samples collected will be highly
variable, and it is not immediately evident how quickly the higher levels would drop due to
deposition. The PM10 samples would be more consistent and relevant to exposures of the popu-
lation. It is not apparent that one can get just as good of an estimate of area-wide lead deposition
from PM10 monitors.
3. One indicator option suggests using scaling Pb-PMw monitoring data up to an
equivalent Pb-TSP level in lieu ofPb-TSP monitoring data. Under what circumstances would it
be appropriate to scale data (e.g., non-source oriented sites, low concentration sites) and when
would it not be appropriate to scale data?
As noted above, along with a tighter standard, scaling is not needed. The data suggest
that the TSP and PM10 levels tend to be quite close.
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Draft Federal Reference Method (FRM) and Federal Equivalent Method (FEM) Criteria for
Lead in PM10 (Pb-PMw)
1. Is it appropriate to use the low-volume PMwc FRM sampler as the Pb-PMw FRM
sampler?
Yes. This monitor is well tested and widely used. The various analysis methods for
lead can directly use the substrates used in this sampler.
2. What other PMw samplers should be considered as either FRM or FEM for the Pb-
PMw FRM?
3. Is XRF an appropriate Pb-PMw FRM analysis method?
While XRF can suffer from non-uniform loading, it is still a very effective approach,
and is compatible with other metals analysis, and is thus very cost effective. It should be speci-
fied as either the FRM or FEM (and if the latter, ICPMS should be the FRM).
4. What other analysis methods should be considered for FRM or FEM for the Pb-PMw
FRM?
As noted above, XRF, if not the FRM, should be FEM, along with AA.
5. Have we selected appropriate precision, bias, and method detection limit require-
ments for FEM evaluation?.
This depends, in part, on the form of the standard (the longer the averaging, the less pre-
cision is needed). The levels provided appear reasonable.
Lead NAAQS Ambient Air Monitoring Network: Network Design Options Under Con-
sideration
1. What types of monitoring sites should be emphasized in the network design (e.g.,
source oriented monitors, population monitors, near roadway monitors)?
Much of the focus of the PM10 monitoring should be placed on source oriented monitor-
ing, which includes near roadways.
2. We are considering proposing requirements for monitoring near sources exceeding
an emissions threshold and discuss a number of options for determining this threshold in the
white paper. What options should be considered in establishing an emissions threshold?
The analysis looks reasonable and well thought out. After a standard is set, one can
back out what level of emissions will lead to likely non-attainment.
B-46
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3. We are considering proposing requirements for non-source oriented monitoring in
large urban areas to provide additional information on ambient air concentrations in urban ar-
eas. Considering other monitoring priorities and a potential requirement for Pb monitoring
near sources, what size of a non-source oriented Pb network is appropriate?
Use of the PM2.5 speciation network can provide much of the needed information as to
identifying areas that have a significant potential to be in non-attainment of at PM10 lead stan-
dard. I would suggest keeping this aspect relatively small.
4. What factors should we base non-source oriented monitoring requirements on (e.g.,
population, design value) ?
I would let the design of the non-source/non-roadway aspects of the PM10 network be
driven by results from the PM2.5 speciation network (and probably even the roadway-oriented
aspects of the network).
5. We are considering proposing requirements for Pb monitoring near roadways and in-
ter states. Is it appropriate to include separate monitoring requirements for near roadway moni-
toring, or should near roadway monitors be apart of the non-source oriented monitoring re-
quirement?
6. Under what conditions would it be appropriate to waive the monitoring requirements
for either source or non-source oriented monitors?
LeadNAAQS Ambient Air Monitoring Network: Sampling Frequency Options Under
Consideration
1. What sampling frequency would be appropriate if the Pb NAAQS is based on a
monthly average?
I would give areas the choice of one in three (or more frequent) and one in six.
2. Is it appropriate to relax the sampling frequency in areas of low Pb concentration? If
so, at what percent of the Pb NAAQS?
If a one in three frequency is chosen, yes, if the monitor indicates Pb levels at 50% or
less of the NAAQS. If a one in six is chosen, then no.
3. Is it appropriate to relax the sampling frequency in areas considerably higher than
the NAAQS? If so, at what percent of the Pb NAAQS?
No.
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Dr. Jay Turner
Draft Comments Submitted by Jay R. Turner (March 25, 2008)
Attachment 1: Options for Lead NAAQS Indicator: Monitoring Implications
Charge Questions
Considering issues such as sampler performance, size cuts, operator maintenance, integra-
tion with other measurement systems, and usefulness as the measurement system for the indi-
cator, please describe the advantages and disadvantages of sampling and analysis ofPb-TSP
versus sampling and analysis ofPb-PM10.
Is it appropriate to monitor for Pb-PMw near Pb sources? And if so, under what conditions?
One indicator option suggests using scaling Pb-PMw monitoring data up to an equivalent
Pb-TSP level in lieu ofPb-TSP monitoring data. Under what circumstances would it be ap-
propriate to scale data (e.g., non-source oriented sites, low concentration sites) and when
would it not be appropriate to scale data?
We have limited data collocated Pb-PM10 and Pb-TSP monitoring data. What types and
"scalingfactors" are appropriate to create using this data (e.g., non-source oriented, source
oriented)? What levels are appropriate for the types of scaling factors identified in the white
paper?
Comments
Clearly Pb-PMlO measurements would be more closely aligned with the current particle-related
compliance monitoring network. That said, the issue is the extent to which the standard must/
should be directly tethered to the properties responsible for adverse effects. Ideally the indicator
would reflect the particle size range of concern. As noted in the memorandum, this is compli-
cated for Pb because the routes of exposure include ingestion as well as inhalation, and thus lar-
ger particle sizes are also of interest. If Pb-TSP is most representative of the particle properties
that should be regulated, then the indicator should reflect this size range either directly (e.g., a
Pb-TSP standard) or indirectly using another indicator such as Pb-PMlO indicator which could
be used in combination with a conservative adjustment to the Pb-TSP threshold value to arrive at
a standard. Note in this case the application of an adjustment would take place in setting the
standard (indicator and threshold value) rather than in the implementation of the standard (using
Pb-PMlO with scaling factors to assess compliance with the Pb-TSP standard).
Role ofPb-PMlO measurements if the indicator is Pb-TSP. Sites with Pb-PMlO greater than the
threshold value for the Pb-TSP indicator clearly violate the standard. Thus, Pb-PMlO could be
used as a screening tool to identify areas of violation with subsequent compliance measurements
using a suitable FRM or FEM technology. The gray zone would be areas that with Pb-PMlO less
than the threshold value for the Pb-TSP indicator. In this case, perhaps very conservative scaling
factors (perhaps even more so than the values highlighted in the memorandum) could be used to
assess the likelihood of noncompliance and trigger the deployment of FRM/FEM measurements.
Development of Scaling Factors. This is an interesting approach and more information would be
helpful in assessing the potential application of scaling factors. Concerning the analysis pre-
sented in the memorandum, the regression suggests negligible increase in Pb-TSP compared to
B-48
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Pb-PMlO for the non source-oriented sites. Was this an ordinary least squares regression (OLS)?
If so, do the regression coefficients significantly change if a Deming-type regression is used? A
footnote states the "original regression gave a negative zero intercept"; the question is whether
the intercept is statistically distinguishable from the origin and this can be determined from the
regression coefficients confidence intervals. Indeed, it would help to have 95% confidence lev-
els on the regression coefficients. While there were 31 sites, virtually all of the concentration
values are below 0.05 |ig/m3. How many of the high concentration values (e.g., greater than 0.1
|ig/m3) came from a single site? This would clarify whether the regression is being strongly in-
fluenced by a single site. The data representation in Figure 1 is visually misleading since axis
ranges are similar but the plot has a high aspect ratio; the figure should be remade as a square
with identical axis range (e.g., 0-0.3 |ig/m3). This will provide a better visual representation of
the relatively high Pb-TSP values observed at relatively low Pb-PMlO values. For the source-
oriented analysis with only two sources, is the data above 0.5 |ig/m3 from a single source?
Attachment 2: Draft Federal Reference Method (FRM) and Federal Equivalent Method
(FEM) Criteria for Lead in PM10 (Pb-PMlO)
Charge Questions
Is it appropriate to use the low-volume PMlOc FRM sampler as the Pb-PMlO FRM sam-
pler?
What other PMw samplers should be considered as either FRM or FEM for the Pb-PMlO
FRM?
Is XRF an appropriate Pb-PMl 0 FRM analysis method?
What other analysis methods should be considered for FRM or FEM for the Pb-PMl 0 FRM?
Have we selected appropriate precision, bias, and method detection limit requirements for
FEM evaluation ?
Comments
If a Pb-PMlO indicator is selected, the low-volume PMlOc sampler should be a suitable Pb-
PM10 FRM sampler if the threshold value is sufficiently high to permit adequate data quality
with analysis by XRF. Using the lowest reported candidate NAAQS level in Table 3 of Attach-
ment 3 (0.02 |ig/m3) and a 4:1 scaling factor for Pb-TSP compared to Pb-PMlO (conservatively
high for the source-oriented scaling factors in Attachment 1), the standard would be about 5
times the estimated XRF MDL (Table 1). Thus, as long as the NAAQS level is in the upper por-
tion of the candidate range (0.02 - 1.5 |ig/m3) the combination of a low-volume PMc sampler
and analysis by XRF should be adequate.
XRF does not require sample digestion. Should other analysis methods be considered FEM des-
ignation, it will be important that the specifics of the extraction protocol be part of the method.
Prior intercomparison studies have clearly demonstrated that equivalency can be achieved for Pb
between XRF and ICP-MS, but such findings might be limited to certain extraction methods.
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Attachment 3: Lead NAAQS Ambient Air Monitoring Network: Network Design Options
Under Consideration
Charge Questions
What types of monitoring sites should be emphasized in the network design (e.g., source ori-
ented monitors, population monitors, near roadway monitors) ?
We are considering proposing requirements for monitoring near sources exceeding an emis-
sions threshold and discuss a number of options for determining this threshold in the white
paper. What options should be considered in establishing an emissions threshold?
We are considering proposing requirements for non-source oriented monitoring in large ur-
ban areas to provide additional information on ambient air concentrations in urban areas.
Considering other monitoring priorities and a potential requirement for Pb monitoring near
sources, what size of a non-source oriented Pb network is appropriate?
What factors should we base non-source oriented monitoring requirements on (e.g., popula-
tion, design value)?
We are considering proposing requirements for Pb monitoring near roadways and inter-
states. Is it appropriate to include separate monitoring requirements for near roadway moni-
toring, or should near roadway monitors be apart of the non-source oriented monitoring re-
quirement?
Under what conditions would it be appropriate to waive the monitoring requirements for ei-
ther source or non-source oriented monitors?
Comments
Emphasis should be placed on population monitoring and source oriented monitoring. In the lat-
ter case, it is important to consider historical industrial activities and not rely solely on contem-
porary emission inventories. For example, in East St. Louis is appears that a significant source
of Pb-PMlO is from resuspension of Pb that was deposited from smelting activities that took
place over the past decades. The Pb sources include not only the currently operating Pb smelter
in Herculaneum but also other Pb smelters that previously operated in the Metro east area but
have been shuttered for decades. Indeed, resuspension of historically-deposited Pb from prior
smelting operations might partially explain the high ratio of ambient Pb to NEI emissions for
AQS ID #171190010 in Granite City, IL (Table 2).
Concerning the analysis of near roadway emissions, it is noted that AQS ID#291892003 in Clay-
ton, MO (Table 7) is located in metropolitan St. Louis and is likely impacted by plumes from the
Herculaneum Pb smelter and potentially the aforementioned resuspension issue (although this
site is somewhat more removed from the zone of historical smelting activity which was concen-
trated in the Metro East area).
Attachment 4: Lead NAAQS Ambient Air Monitoring Network: Sampling Frequency Op-
tions Under Consideration
Charge Questions
What sampling frequency would be appropriate if the Pb NAAQS is based on a monthly av-
erage?
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Is it appropriate to relax the sampling frequency in areas of low Pb concentration? If so, at
what percent of the Pb NAAQS?
Is it appropriate to relax the sampling frequency in areas considerably higher than the
NAAQS? If so, at what percent of the Pb NAAQS?
Comments
It is likely that l-in-3 day or higher frequency would be needed to obtain a stable monthly aver-
age values. Given that the Pb will often be associated with the coarse PM fraction and the sensi-
tivity of coarse PM to environmental conditions, sampling frequencies greater than l-in-6 days
will most certainly be needed in most cases.
Any thoughts on how concentration values below MDL would be imputed?
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Dr. Warren H. White
Comments on Monitoring for Pb NAAQS
Warren H. White
AAMM Consultation, 25 March 2008 Teleconference
The charge questions given the Subcommittee include the following general groupings.
1. Selection of sampling technology and siting:
... sampling and analysis ofPb-TSP versus sampling and analysis ofPb-PMlO.
... monitor for Pb-PMlO near Pb sources?
... "scalingfactors "?
... appropriate to use the low-volume PM10 FRMsampler?
Purely as sampling technology, the advantages of the lo-vol PMio sampler over hi-vol TSP
should be decisive. The PMi0 FRM collects a well-characterized and replicable sample on a
clean substrate that is well-suited to XRF analysis. As I noted during the call, the uniformity of
the sample deposit collected by any sampler can affect the precision of XRF analyses and should
be verified before a final commitment to this approach. The fact that the lo-vol sampler is auto-
mated and already widely deployed is no small additional virtue. As several CASAC and
AAMM commenters have already observed, a TSP-PMio scaling factor is an unnecessary dis-
traction to the consideration of an order-of-magnitude change in the level.
EPA hesitates to adopt a 10-micron particle-size cut for Pb because ingestion of larger particles
is believed a significant exposure pathway for children, the most sensitive group. The relevance
of air monitoring for assessing the ingestion of ultra-coarse Pb depends on the following specific
questions:
Are the ingested particles from ongoing or historical air emissions?
Do they arrive by air or are they tracked in by tires and shoes?
These questions lie in the areas of exposure- and risk-assessment presumably represented and
actively considered by members of the CASAC Pb panel. They lie outside the areas of special
expertise for which I and other members of the AAMM subcommittee were selected, so I defer
to CASAC's unambiguous recommendations on sampling technology and siting.
2. S el ecti on of analy si s method s:
... XRF an appropriate Pb-PMlO FRM analysis method?
... appropriate precision, bias, and method detection limit requirements for FEM?
As the documentation notes, XRF is a relatively inexpensive and reasonably sensitive method
that would also provide information on other metals of potential concern. A paper* that is cur-
rently in review at ES&T reports that the routine Pb-PM2.5 measurements in the CSN/STN and
IMPROVE networks demonstrate XRF detection limits of 5-7 ng/cm2, corresponding to air lev-
els of ~3 ng/m3 for a 24h sample at 16.7 1pm. The paper defined this as the actual Pb concentra-
tion at which 95% of the observations detect Pb and report it to be significantly above blank lev-
els.
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* N.P. Hyslop and W.H. White, An Empirical Approach to Estimating Detection Limits using
Collocated Data.
3. Sampling frequency options:
... if the Pb NAAQS is based on a monthly average ?
... in areas of low Pb concentration?
... in areas considerably higher than the NAAQS?
One-in-six-day sampling clearly will not produce a reliable estimate of the monthly average.
Determining an appropriate sampling frequency will require specification of acceptable rates for
Type I and Type II decision errors, along with careful statistical modeling, and all this will be
part of the DQO process that is undertaken before any new monitoring plan is finalized. During
the call I asked whether there was any reason to believe that a month of high concentrations, in a
year of otherwise low concentrations, is more harmful to a child's development than the same
number of high concentrations scattered throughout the year. I have subsequently waded
through enough of the Criteria Document to understand the prudence of considering current as
well as cumulative exposures. However ingestion, where the questions of current vs. historical
emissions and atmospheric transport vs. surface tracking still seem open, may not track current
air concentrations.
For a given analytical method, there is little value in frequent sampling if concentrations are only
marginally detectable. However I would be inclined to maintain normal sampling frequencies in
any location with routinely measurable levels. As other committee members noted, at concentra-
tions much higher than NAAQS there is a need to verify the atmospheric effects of the control
measures undertaken. At concentrations well below NAAQS, we should keep in mind the possi-
bility that next decade's Pb CAS AC panel may find itself reviewing new evidence of adverse
effects at levels below today's contemplated NAAQS.
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Dr. Yousheng Zeng
CASAC AAMM Subcommittee Review of
Ambient Air Monitoring Options for Lead (Pb) NAAQS
Comments from AAMM Subcommittee Member Yousheng Zeng
Options for Lead NAAQS Indicator: Monitoring Implications
I think that Pb-PMi0 is a better indicator than Pb-TSP. Although Pb-TSP includes the contribu-
tion from larger particles, it will not serve well as an indicator for NAAQS. The primary con-
cern for the Pb NAAQS and its indicator is air quality which directly relates to the inhalation
pathway. Ingestion is an important Pb pathway; however, measuring Pb-TSP neither offers a
quantitative connection to the level of ingestion exposure nor measures the Pb deposition rate
that may be more relevant to ingestion. Since Pb-TSP is not a good indicator for these pathways,
it is unclear what benefit will be gained from measuring Pb-TSP. If we monitor Pb-PMi0, at
least we get a good indicator for the inhalation pathway.
With leaded gasoline phased out, vehicle tailpipe emissions are no longer a significant source of
Pb. Stationary Pb sources are regulated by MACT and other federal and state rules. With these
regulatory controls, Pb emissions from stationary sources are likely associated with PMio. Very
little of the PM emissions from these sources resemble TSP. If the objective of measuring ambi-
ent Pb levels is to monitor impacts of freshly emitted Pb, using Pb-PMio is better than Pb-TSP
even for monitors near stationary sources. Pb-TSP is most likely re-suspended PM. Because it
is re-suspended, it does not represent net deposition. If we want to measure the dust that may
cause ingestion risk, it would be much more direct and easier to measure the Pb concentration in
soil or dust samples.
Using Pb-PMio is consistent with monitoring PMio. It helps streamline our monitoring efforts.
Using Pb-PMio will also be consistent with the New Source Review (NSR) permitting program.
As part of NSR Prevention of Significant Deterioration (PSD) modeling analyses, emissions
from stationary sources will be modeled. The data from the facilities will likely be based on
Because the above reasons, we should replace Pb-TSP with Pb-PMi0. There is no value in scal-
ing Pb-PMio monitoring data to an equivalent Pb-TSP level.
A more high level comment - If the inhalation pathway is not a significant health concern for Pb,
why not remove Pb from the NAAQS list and manage it as other metals such as mercury, cad-
mium, etc.? Pb had its place in NAAQS when leaded gasoline was widely used. Now, the
sources and health impacts of Pb are comparable to other metals. EPA uses MACT to control Pb
sources. EPA can use the residual risk management approach or the approach used in hazardous
waste combustion to minimize the health risk. This approach can incorporate both direct and
indirect exposure, which has the benefit of addressing inhalation and ingestion pathways explic-
itly and not causing the confusion discussed above.
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Draft Federal Reference Method (FRM) and Federal Equivalent Method (FEM) Criteria for
Lead in PM10 (Pb-PM10)
I like the idea proposed by Mr. Dirk Felton to use AA as FRM for sample analysis and use XRF
as FEM. EPA should evaluate this approach.
Lead NAAQS Ambient Air Monitoring Network: Network Design Options under Considera-
tion
The third analysis in this EPA memo used the SCREENS model to help establish source oriented
monitoring thresholds. The SCREENS model was used without considering building downwash,
yet the modeling results were referred to as worst cases. Consideration of building downwash
could yield higher modeled impacts than the results in this memo. It would be better to use site-
specific, more realistic modeling analyses and the final Pb NAAQS to determine whether or not
ambient monitoring is required near stationary sources.
In the PSD program, there is a threshold for site-specific, pre-construction Pb monitoring. The
threshold is 0.1 ug/m3 for the current Pb NAAQS of 1.5 ug/m3, i.e., approximately 7% of the
NAAQS. Once the new Pb NAAQS is finalized, EPA may consider using a similar approach to
set the near-source monitoring requirements. For example, if the new Pb NAAQS is 0.2 ug/m3,
the monitoring threshold will be 0.014 ug/m3. If site-specific modeling (with building down-
wash considered) yields a result higher than 0.014 ug/m3 (corresponding emission rate in tons
per year may change from site to site due to different dispersion conditions), then a monitor
should be installed.
The monitoring requirements should be somewhat flexible. If the monitoring results are always
well below the NAAQS for one or two years, then the monitoring requirements may be reduced
or waved.
Lead NAAQS Ambient Air Monitoring Network: Sampling Frequency Options under Consid-
eration
If the averaging period for the Pb NAAQS changes from quarterly to monthly, then the sampling
frequency should be changed. The specific frequency should be determined based on EPA's
DQO model. EPA may consider relaxing the sampling frequency if the monitoring results are
low - as an example, if average monthly results are 75% of the new Pb NAAQS, then the fre-
quency can be relaxed from l-in-2 to l-in-3. If the results are only 50% of the new NAAQS,
then the frequency may be further relaxed to l-in-6.
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Dr. Barbara Zielinska
CASAC Ambient Air Monitoring & Methods Subcommittee Teleconference: Comments
on the Lead NAAQS Indicator, Monitoring and Sampling Frequency
Barbara Zielinska
In the January 22, 2008 letter to the EPA Administrator, the CASAC Lead Panel unani-
mously recommended that the Agency revises the indicator for lead sampling from TSP to PMi0.
I continue to support this recommendation. The letter said:
"The agency should seize this opportunity to transition from TSP to PMi0, since the current re-
view indicates a need for a substantial lowering of the lead NAAQS. If a standard is lowered by
a factor of 10 to 100, it is unimportant if the indicator measures 10% or 15% less than the indica-
tor selected 30 years ago.< .. > Rather than needing to arduously establish a large series of site-
specific PMlO-Pb to TSP-Pb ratios (which would, in essence, constitute "fitting good data to
bad"), it would be well within the Agency's range of discretionary options to accept a slight loss
of ultra-coarse lead at some monitoring sites by selecting an appropriately conservative level for
the revised Pb NAAQS. Conversely, it would be a mistake to hold up the old TSP metric as the
"gold standard" and only allow newer, better technology if it can reproduce the old, and seri-
ously-flawed, sampler performance."
I do agree with this reasoning.
Charge questions, Attachment 1, Options for Lead NAAQS Indicator: Monitoring Implica-
tions:
1. Considering issues such as sampler performance, size cuts, operator maintenance, in-
tegration with other measurement systems, and usefulness as the measurement system
for the indicator, please describe the advantages and disadvantages of sampling and
analysis ofPb-TSP versus sampling and analysis ofPb-PMlO.
As depicted in the individual comments attached to the January 22, 2008, CASAC letter, the TSP
monitor represents old, 1950s technology and its accuracy is questionable. Hi-Vol TSP is non-
size specific and its 50% size cut point of 30 - 50 jim particles depends greatly on a wind speed
and direction. Contrary to Pb-TSP, Pb-PMio is inhalable and can travel longer distances from
emission sources. Currently, TSP monitors are used only for Pb-TSP measurements. It is time
that the EPA abandons this old technology and moves towards more precise PMio measurements.
The great advantage of this strategy is the existing PMio network and thus a possibility of inte-
gration with other measurement systems.
2. Is it appropriate to monitor for Pb-PMlO near Pb sources? And if so, under what
conditions?
Yes, it is. Pb-PMi0 should be monitored near the major Pb sources to get the idea about Pb con-
centrations in this inhalable particle size range. Since Pb-containing larger than 10 jim particles
may be important in the vicinity of large Pb point sources, such as Pb smelters or areas with con-
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siderable Pb tailings, Pb-TSP monitoring should be continued in these areas. However, since the
present TSP monitors are not accurate, the deployment of new, low-volume TSP samplers should
be encouraged in these areas. There is certainly a need for getting a better understanding of Pb
emissions in various particle sizes near the major Pb sources.
3. One indicator option suggests using scaling Pb-PMlO monitoring data up to an
equivalent Pb-TSP level in lieu of Pb-TSP monitoring data. Under what circum-
stances would it be appropriate to scale data (e.g., non-source oriented sites, low
concentration sites) and when would it not be appropriate to scale data?
I don't think scaling is a good idea. As emphasized in the CASAC's January 22, 2008 letter, a
scaling is equivalent to fitting "good data to bad". Also, see my answer to charge question #4
below.
4. We have limited data collocated Pb-P 10 and Pb-TSP monitoring data. What types
and "scalingfactors" are appropriate to create using this data (e.g., non-source ori-
ented, source oriented)? What levels are appropriate for the types of scaling factors
identified in the white paper?
Kevin Cavender's memo from March 3, 2008 emphasizes that all size Pb particles con-
tribute to exposures and associated health effects. This is true, but it does not necessary mean
that the Pb-PMi0 standard has to be tied to Pb-TSP. As shown in this document, non-source ori-
ented Pb-TSP and Pb-PMio monitor data (Figure 1) show strong linear relationship and the ratio
of Pb-PMio to Pb- TSP close to unity. Rather than trying to decide if Pb-TSP = Pb-
PMio* 1.014+0.028 or +0.017, the Pb-PMio standard can be set at a slightly more conservative
level. For source-oriented monitor data, Figure 2 indicates that the relationship between Pb-TSP
and Pb-PMio is driven by the highest Pb concentrations. If the standard is set at the level below
0.5 |ig/m3, it is unimportant if 1 |ig/m3 Pb-PMio concentration corresponds to 1.39 or 2.2 |ig/m3
of Pb-TSP. These values are much above the standard anyway. Rather, the relationship for the
concentrations in the range of expected Pb standard (below 0.5 |ig/m3) should be examined. This
hasn't been done in this document; however, low accuracy of hi-Vol TSP samplers in this low
concentration range, may make such a comparison not reliable.
Charge questions, Attachment 2, Draft FRM and FEM Criteria:
1. Is it appropriate to use the low-volume PM10 FRM sampler as the Pb-PMlO FRM sam-
pler?
Yes, it is.
2. What other PM10 samplers should be considered as either FRM or FEM for the Pb-
PM10FRM?
Low-volume, sequential PMio FRM sampler is the best candidate for the Pbio FRM.
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3. Is XRF an appropriate Pb-PMl 0 FRM analysis method?
I believe, yes, it is. XRF has an adequate sensitivity, is relatively inexpensive, non-destructive
and allows for simultaneous measurements of other elements.
4. What other analysis methods should be considered for FRM or FEMfor the Pb-PMlO
FRM?
Modern analytical methods that can be used to quantify Pb include graphite furnace AA,
TCP/atomic emission spectroscopy (ICP/AES), or ICP/mass spectrometry (ICP/MS).
5. Have we selected appropriate precision, bias, and method detection limit requirements
for FEM evaluation?
The selected levels seem reasonable.
Charge questions, Attachment 3, Ambient Monitoring Network:
1. What types of monitoring sites should be emphasized in the network design (e.g., source
oriented monitors, population monitors, near roadway monitors)?
All three types are useful, but in my opinion source oriented monitors should have the high-
est priority.
2. We are considering proposing requirements for monitoring near sources exceeding an
emissions threshold and discuss a number of options for determining this threshold in the
white paper. What options should be considered in establishing an emissions threshold?
All three options considered in this document appear to be reasonable. I favor the second option,
which is based on the measurements near Pb sources. The maximum impact of 0.7 |ig/m3 per
tpy is consistent with the results obtained by the screening model. After the Pb standard is estab-
lished, it should be possible to estimate what level of Pb emissions may lead to non-attainment.
As noted in the document, since these threshold estimates are on the conservative site, it would
be appropriate to include an option for the monitoring agencies to request a waiver for monitor-
ing requirements if it could be shown that the source is very unlikely to cause the ambient air Pb
concentrations to exceed 70% of the NAAQ Pb standard.
3. We are considering proposing requirements for non-source oriented monitoring in large
urban areas to provide additional information on ambient air concentrations in urban
areas. Considering other monitoring priorities and a potential requirement for Pb moni-
toring near sources, what size of a non-source oriented Pb network is appropriate?
Presumably NCore sites will perform Pb measurements. I don't think there is a need for separate
Pb monitors, if the existing PMio monitoring network can be utilized for this purpose. The addi-
tional analysis cost for Pb is very reasonable, if XRF method is used. In addition, PM2.5 monitor-
ing network can provide some information regarding Pb concentrations in this PM size fraction.
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4. What factors should we base non-source oriented monitoring requirements on (e.g.,
population, design value) ?
I suspect that the proximity to Pb sources may be important. Pb is a primary pollutant and it can
be transported significant distances if present in the inhalable PM fraction.
5. We are considering proposing requirements for Pb monitoring near roadways and inter-
states. Is it appropriate to include separate monitoring requirements for near roadway
monitoring, or should near roadway monitors be apart of the non-source oriented moni-
toring requirement?
From data presented in this document (Table 7) it is not clear that the proximity to the roadway
results in a higher Pb ambient concentration. Unless the NAQS is established at a very low level
(<0.1 |ig/m3) these monitors should probably be part of the non-source oriented monitoring net-
work.
6. Under what conditions would it be appropriate to waive the monitoring requirements for
either source or non-source oriented monitors?
This subject is addressed in question #2 above and in charge questions for attachment 4.
Charge questions, Attachment 4: Sampling Frequency Options:
1. What sampling frequency would be appropriate if the Pb NAAQS is based on a monthly
average?
I agree with the document that if the Pb NAAQS is based on a monthly average, the l-in-6 day
sampling schedule is not frequent enough. A l-in-3 day sampling frequency would yield 10
samples at 100% completeness or 7 at 75%. If this is enough or not, it is difficult to say without
having the actual data that would allow for the estimate of uncertainties associated with different
sampling frequencies. According to the document, the EPA plans to evaluate every day, l-in-3
day and l-in-6 day sampling frequencies and provide a general margin of error about a mean
monthly estimate, focusing on estimates close to the proposed NAAQS. After this task is com-
pleted, it would be more obvious which sampling frequency is sufficient. The appropriate sam-
pling frequency depends also on the statistical form of the Pb standard.
2. Is it appropriate to relax the sampling frequency in areas of low Pb concentration? If so,
at what percent of the Pb NAAQS?
I think yes, it is. The document proposes a reduction in sampling frequency to l-in-6 day, if all
12 monthly averages in a calendar year are lower than 30% of the Pb NAAQS. This seems rea-
sonable to me, although 50% is probably sufficient. If an area elects to stay with the higher sam-
pling frequency, this should be allowed.
3. Is it appropriate to relax the sampling frequency in areas considerably higher than the
NAAQS? If so, at what percent of the Pb NAAQS?
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No, these data are important for an adequate evaluation of potential health effects. In addition, if
a source emits larger quantities of Pb periodically, more frequent monitoring may be considered.
One minor comment on Attachment 4: Figure 1 did not translate well in the Adobe PDF version
of this document.
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Appendix C - Agency's Background and Charge Memorandum to the
CASAC AAMM Subcommittee
UNITED STATES ENVIRONMENTAL PROTECTION AGENCY
RESEARCH TRIANGLE PARK, NC 27711
March 3, 2008
MEMORANDUM
SUBJECT: CASAC Review of Ambient Air Monitoring Options for Lead (Pb) National
Ambient Air Quality Standards (NAAQS)
FROM: Lewis Weinstock /Signed/
Acting Group Leader
Ambient Air Monitoring Group
Office of Air Quality Planning and Standards (D243-02)
TO: Fred Butterfield
Designated Federal Officer
Clean Air Scientific Advisory Committee
EPA Science Advisory Board Staff Office (1400F)
Attached are materials for review by the Clean Air Scientific Advisory Committee's
(CASAC) Ambient Air Monitoring and Methods (AAMM) Subcommittee. These materials will
be the subjects of a consultation by the AAMM Subcommittee, scheduled for a teleconference to
be held on March 25, 2008. I am requesting that you forward these materials to the AAMM Sub-
committee to prepare for the consultation.
This project, entitled Lead National Ambient Air Quality Standards (NAAQS) Review:
Indicator and Monitoring Issues, has been requested by EPA's Office of Air Quality Planning
and Standards (OAQPS), within EPA's Office of Air and Radiation, in anticipation of potential
revisions to the Pb NAAQS. The consultation will cover the lead (Pb) National Ambient Air
Quality Standards (NAAQS) indicator as well as several monitoring topics under consideration
for the upcoming notice of proposed rulemaking.
The consultation on the Pb NAAQS indicator will solicit Subcommittee comments and
advice on several options that have been identified that would low volume Pb in PMio (Pb-PMio)
monitors to be used in the NAAQS surveillance monitoring network. The consultation on the
draft Pb in PMio Federal Reference Method (FRM) and Federal Equivalent Method (FEM) crite-
ria will assist EPA in developing these methods for use in measuring Pb in PMio. The consulta-
tion on network design options will provide Subcommittee comments .and advice on how the Pb
C-l
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surveillance monitoring network should be structured to ensure proper monitoring coverage in
areas likely to exceed the Pb NAAQS as well as provide information on typical population expo-
sures in large urban areas. Finally, the consultation on sampling frequency will solicit Subcom-
mittee comments on the appropriate sampling frequency in the case that the NAAQS averaging
time is reduced to a monthly average. Charge questions associated with each part of the consul-
tation are provided below.
The upcoming consultation will support the EPA by providing scientific advice as the
EPA Administrator considers potential revisions to the Pb NAAQS; a notice of proposed rule-
making is to be signed by May 1, 2008. Although this consultation does not call for a consensus
statement, we are requesting each of the members provide his or her individual written com-
ments on an expedited schedule to assist EPA in meeting the May 1, 2008 deadline for proposing
the Pb NAAQS.
Following consultation, the Agency will issue a notice of proposed rulemaking with re-
gard to our review of the Pb NAAQS, together with proposed changes to the associated monitor-
ing requirements and the draft FRM for Pb in PMi0. Note that due to a court order, any monitor-
ing requirement changes needed to implement the revised NAAQS must be promulgated at the
same time as the final NAAQS standard. A peer review by the Subcommittee of the final FRM
for Pb in PMi0 may be appropriate for future consideration.
We appreciate the efforts of you and the Subcommittee to prepare for the upcoming
meeting and look forward to discussing this project in detail on March 25, 2008. Questions re-
garding the enclosed materials should be directed to Mr. Kevin Cavender, EPA-OAQPS (phone:
919-541-2364; e-mail: cavender.kevin@epa.gov).
Documents Associated with Subcommittee's Consultation:
The purpose of the upcoming CAS AC AAMM Subcommittee meeting is to provide con-
sultation on several aspects of potential ambient air monitoring requirements for the Pb NAAQS.
The attached documents summarize the aspects being considered and provide various options
under consideration. The Agency requests that the Subcommittee focus on the associated charge
questions as part of its review.
Attachment 1 - Options for Lead NAA QS Indicator: Monitoring Implications
Background and Summary: Lead in total suspended particulate (TSP) is the current indi-
cator for the lead NAAQS. Concerns have been raised regarding the quality of the data gen-
erated by the high volume TSP sampler due to perceived poor precision and an upper particle
cut size that varies widely as a function of wind speed and direction. CAS AC has recom-
mended that EPA move towards the use of Pb in PMi0 as the indicator for the Pb NAAQS.
In response to CASAC's concerns and comments, the EPA is considering options which that
would allow Pb in PMi0 to be used as the indicator or to allow Pb in PMi0 data to be used in
lieu of Pb in TSP data while maintaining Pb in TSP as the indicator. The attached document
discusses the options under consideration for the Pb NAAQS indicator.
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Charge Questions:
Considering issues such as sampler performance, size cuts, operator maintenance, integra-
tion with other measurement systems, and usefulness as the measurement system for the indi-
cator, please describe the advantages and disadvantages of sampling and analysis ofPb-TSP
versus sampling and analysis ofPb-PMw.
Is it appropriate to monitor for Pb-PMw near Pb sources? And if so, under what conditions?
One indicator option suggests using scaling Pb-PMw monitoring data up to an equivalent
Pb-TSP level in lieu ofPb-TSP monitoring data. Under what circumstances would it be ap-
propriate to scale data (e.g., non-source oriented sites, low concentration sites) and when
would it not be appropriate to scale data?
We have limited data collocated Pb-PMw and Pb-TSP monitoring data. What types and
"scalingfactors" are appropriate to create using this data (e.g., non-source oriented, source
oriented)? What levels are appropriate for the types of scaling factors identified in the white
paper?
Attachment 2 - Draft Federal Reference Method (FRM) and Federal Equivalent Method
(FEM) Criteria for Lead in PM10 (Pb-PM10)
Background and Summary: In order for monitoring data to be used in determination of at-
tainment with the NAAQS, the data must be collected with a FRM or FEM. A number of
options under consideration for the Pb NAAQS indicator would require the EPA to develop a
FRM and FEM criteria for the measurement of Pb in PMio. The EPA has drafted language
for a FRM for Pb in PMio based on the existing FRM sampler for low volume PMi0c in Ap-
pendix O to Part 50 of the Code of Federal Regulations (CFR) coupled with analysis by x-ray
fluorescence (XRF). In addition, minor changes to the FEM criteria for Pb methods have
been drafted to make these requirements consistent with the draft FRM for Pb in PMio. The
attached document summarizes the rationale for the proposed changes and includes a draft of
the FRM and FEM CFR text.
Charge Questions:
Is it appropriate to use the low-volume PMwc FRM sampler as the Pb-PMw FRM sampler?
What other PMw samplers should be considered as either FRM or FEM for the Pb-PMw
FRM?
Is XRF an appropriate Pb-PMw FRM analysis method?
What other analysis methods should be considered for FRM or FEM for the Pb-PMw FRM?
Have we selected appropriate precision, bias, and method detection limit requirements for
FEM evaluation ?
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Attachment 3 - Lead NAAQS Ambient Air Monitoring Network: Network Design Options
Under Consideration
Background and Summary: The existing Pb-TSP network has decreased substantially over
the last few decades. In 1980 there were over 900 Pb-TSP sites; this number has been re-
duced to approximately 200 sites. Several states have no Pb-TSP samplers resulting in large
portions of the country with no data on current ambient Pb-TSP concentrations. In addition,
many of the largest Pb-emitting sources in the country do not have nearby samplers, and
there is substantial uncertainty about ambient air Pb levels resulting from historic Pb deposits
near roadways. As a result, the existing network and network requirements may not be ade-
quate to support a lower Pb NAAQS. The attached document identifies a number of network
design options under consideration.
Charge Questions:
What types of monitoring sites should be emphasized in the network design (e.g., source ori-
ented monitors, population monitors, near roadway monitors) ?
We are considering proposing requirements for monitoring near sources exceeding an emis-
sions threshold and discuss a number of options for determining this threshold in the white
paper. What options should be considered in establishing an emissions threshold?
We are considering proposing requirements for non-source oriented monitoring in large ur-
ban areas to provide additional information on ambient air concentrations in urban areas.
Considering other monitoring priorities and a potential requirement for Pb monitoring near
sources, what size of a non-source oriented Pb network is appropriate?
What factors should we base non-source oriented monitoring requirements on (e.g., popula-
tion, design value)?
We are considering proposing requirements for Pb monitoring near roadways and inter-
states. Is it appropriate to include separate monitoring requirements for near roadway moni-
toring, or should near roadway monitors be apart of the non-source oriented monitoring re-
quirement?
Under what conditions would it be appropriate to waive the monitoring requirements for ei-
ther source or non-source oriented monitors?
Attachment 4 - Lead NAAQS Ambient Air Monitoring Network: Sampling Frequency
Options Under Consideration
Background and Summary: The current Pb sampling frequency requirement is for one 24-
hour sample every six days. For the current NAAQS, which is based on a quarterly average,
the l-in-6 sampling schedule yields 15 samples per quarter on average with 100% complete-
ness, or 12 samples with 75% completeness. A change to a monthly averaging period would
result in between 4 and 6 samples per month at the current sampling frequency with 100%
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completeness, or between 3 and 5 samples with 75% completeness. If we change the averag-
ing time to a monthly average, we may need to increase the sampling frequency to better re-
flect ambient Pb concentrations during the averaging period. The attached document de-
scribes several options we are considering which would increase the sampling frequency.
Charge Questions:
What sampling frequency would be appropriate if the Pb NAAQS is based on a monthly av-
erage?
Is it appropriate to relax the sampling frequency in areas of low Pb concentration? If so, at
what percent of the Pb NAAQS?
Is it appropriate to relax the sampling frequency in areas considerably higher than the
NAAQS? If so, at what percent of the Pb NAAQS?
Attachments
cc: Richard Wayland, OAQPS/AQAD
Bill Lamason, OAQPS/AQAD
Deirdre Murphy, OAQPS/HEID
Karen Martin, OAQPS/HEID
Fred Dimmick, OAQPS/NERL
Robert Vanderpool, ORD/NERL
Phil Lorang, OAQPS/AQAD
Mike Papp, OAQPS/AQAD
Mark Schmidt, OAQPS/AQAD
Joann Rice, OAQPS/AQAD
Louise Camalier, OAQPS/AQAD
Tim Hanley, OAQPS/AQAD
James Hemby, OAQPS/AQAD
Mark Schmidt, OAQPS/AQAD
Kevin Cavender, OAQPS/AQAD
C-5
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