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> **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 Standards (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 technical 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 result 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-

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

cc: Marcus Peacock, Deputy Administrator

Robert Meyers, Acting Assistant Administrator, OAR

Dr. Rogene Henderson, CASAC Chair

Attachments

**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 Engineering, 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 Resources 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 University of New York, Albany, NY

**Dr. Delbert Eatough**, Professor of Chemistry, Emeritus, Chemistry and
Biochemistry Department, Brigham Young University, Provo, UT

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

**Mr. Henry (Dirk) Felton**, Research Scientist, Division of Air
Resources, Bureau of Air Quality Surveillance, New York State Department
of Environmental Conservation, Albany, NY

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

**Dr. Rudolf Husar**, Professor, Mechanical Engineering, Engineering and
Applied Science, Washington University, St. Louis, MO

**Dr. Kazuhiko Ito**, Assistant Professor, Environmental Medicine,
School of Medicine, New York University, Tuxedo, NY

**Dr. Thomas Lumley**, Associate Professor, Biostatistics, School of
Public Health and Community Medicine, University of Washington, Seattle,
WA

**Dr. Peter McMurry**,\* Professor, Department of Mechanical
Engineering, Institute of Technology, University of Minnesota,
Minneapolis, MN

**Mr. Richard L. Poirot**, Environmental Analyst, Air Pollution Control
Division, Department of Environmental Conservation, Vermont Agency of
Natural Resources, Waterbury, VT

**Dr. Kimberly 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
([[butterfield.fred@epa.gov]{.underline}](mailto:butterfield.fred@epa.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.

**Appendix B -- Comments from Individual CASAC**

**AAMM Subcommittee Members**

> This appendix contains the preliminary and/or final written comments
> of individual 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 Subcommittee 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.

**[Panelist]{.underline} [Page \#]{.underline}**

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

**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:]{.underline} Options for Lead
NAAQS Indicator: Monitoring Implications.

1\. \...please describe the advantages and disadvantages of sampling and
analysis of Pb-TSP versus sampling and analysis of Pb-PM10.

2\. Is it appropriate to monitor for Pb-PM10 near Pb sources? And if so,
under what conditions?

3\. One indicator option suggests using 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?

4\. We have limited data collocated Pb-PM10 and Pb-TSP monitoring data.
What types and "scaling factors" 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]{.underline}:

Assuming the Pb NAAQS is substantially tightened to the high end of the
CASAC range (0.2 μg/m^3^), 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 connection
between levels of lead measured in the air and actual dose of lead to
sensitive populations 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.

[Questions associated with Attachment 2:]{.underline} Draft Federal
Reference Method (FRM) and Federal Equivalent Method (FEM) Criteria for
Lead in PM10 (Pb-PM10):

1\. Is it appropriate to use the low-volume PM10-c FRM sampler as the
Pb-PM10 FRM sampler?

2\. What other PM10 samplers should be considered as either FRM or FEM
for the Pb-PM10

FRM?

3\. Is XRF an appropriate Pb-PM10 FRM analysis method?

4\. What other analysis methods should be considered for FRM or FEM for
the Pb-PM10 FRM?

5\. Have we selected appropriate precision, bias, and method detection
limit requirements for

FEM evaluation?

[Comments:]{.underline}

This attachment is very well written with only minor omissions. It is
appropriate to use the low-volume PM10-c FRM sampler as the Pb-PM10 FRM
sampler. Sequential PM10 samplers should also be allowed, either as FRM
or FEM samplers. The dichotomous sampler is an obvious candidate for an
FEM sampler for lead. While XRF may be appropriate for an FEM analytical
method, ICPMS or GFAA should be used for the FRM analytical method since
those methods 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 suffer 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:]{.underline} 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 oriented monitors, population monitors, near
roadway monitors)?

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?

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., population, 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 either source or non-source oriented
monitors?

[Comments:]{.underline}

First, not knowing what the final lead NAAQS will be (including the
form, not just the concentration), it is very difficult to comment on
network design. But assuming the final NAAQS will not be lower than 0.2
μg/m^3^, with a form that does not substantially weaken the effective
standard, I would suggest the network focus on source and population
oriented sites. For source oriented 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 reasonable approaches that lead air levels are
well below the NAAQS, then less monitoring should be done.

[Questions associated with Attachment 4:]{.underline} 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 average?

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:]{.underline}

First I want to clearly state that sampling frequency issues (and the
level of public health protection) 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 frequency 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 inconsistent with the health concerns
leading us towards a 1-month metric. Additionally, for a given NAAQS
value such as 0.2 μg/m^3^, a form as noted above results in a
substantially weaker lead NAAQS than a simple 1-month form.

**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 comment 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 sampling and analysis of
Pb-TSP versus sampling and analysis of Pb-PM~10~.*

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 suspended particulates (TSP).
EPA should move toward Pb-PM~10~, which is inhalable and can travel
longer distances from emission sources.

[Disadvantages]{.underline}: The TSP size fraction was defined by the
dimensions of the high-volume (HiVol) 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 µm 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
opening 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 nature of the TSP samples and
considering the question of how well Pb-TSP can represent human
exposure, this 1950s technology should be discontinued.

[Advantages]{.underline}: The only advantage of keeping Pb-TSP is that a
large body of Pb-TSP concentrations 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.

The low-volume (16.7 L/min) PM~10~ inlet is wind-tunnel tested with
specified collocated precision over a wide range of wind speeds and
directions (Watson and Chow, 1993; 2001). Low volume PM~10c~ FRMs
(Appendix O to Part 50) provide more flow control, low background
Teflon-membrane filters, and more precise mass determination. It is also
similar to PM~2.5~ FRM (using the same PM~10~ impactor inlet with the
addition of WINS or sharp-cut cyclone inlets). The low-volume PM~10c~
FRM sampler is consistent with the EPA current proposed difference
method for PM~10-2.5~, which is similar (e.g., filter medium, sample
collection, gravimetric analysis, quality assurance \[QA\]/quality
control \[QC\]) to new or existing PM data set(s). Since low-volume
PM~10~ samplers have been widely deployed in many urban networks, they
are commercially available and network operators are familiar with them,
the cost for additional sampling and analysis should be reasonable.
There is no need for a separate Pb-PM~10~ network. The integrated air
monitoring strategy (U.S.EPA, 2005) should be considered for Pb-PM~10~
monitoring (Scheffe et al., 2007)

![](media/image2.jpeg){width="4.972222222222222in"
height="3.5854166666666667in"}

**Figure 1.** Non-attainment areas for lead (from
<http://www.epa.gov/oar/oaqps/greenbk/maplead.html>).

*Question 2: Is it appropriate to monitor for Pb-PM~10~ near Pb sources?
And if so, under what conditions?*

Yes, Pb-PM~10~ 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 urban 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 drastically, 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 in the NEI (Attachment 3)
is a good start. PM~10~ levels near Pb sources should be monitored 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-PM~10~
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?*

Even though the analysis for measurements between 1993 and 2006 shows
good correlations between Pb-TSP and PM~10~ for 33 non-source-oriented
sites, 40% of the Pb-TSP concentrations 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 PM~10~. A better question is: "What is the
purpose for scaling Pb-PM~10~ 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 PM~10~ data can be used to set up new Pb-PM~10~ NAAQS.
The U.S. EPA should acquire Pb-PM~10~ and analyze archived PM~10~
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 PM~10~ and it is more difficult to
establish Pb-PM~10~ and Pb-TSP relationships under high wind speeds.

*Question 4: We have limited data 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 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-PM~10~ 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** \[Draft Federal Reference Method (FRM) and
Federal Equivalent Method (FEM) Criteria for Lead in PM10 (Pb-PM10)\]

*Question 1:* *Is it appropriate to use the low-volume PM~10c~ FRM
sampler as the Pb-PM~10~ FRM sampler?*

Yes, as stated in the response to Question 1 of Attachment 1. A
low-volume PM~10c~ FRM sampler as the Pb-PM~10~ FRM sampler is the most
cost-effective way. There shouldn't be any difference in low-volume
PM~10c~ samplers for PM~10~ mass or Pb.

*Question 2: What other PM~10~ samplers should be considered as either
FRM or FEM for the Pb-PM~10~ FRM?*

Although there are medium-volume and HiVol PM~10~ FRM samplers (see
Table 2 of Chow, 1995, reproduced below) that can be considered as
alternatives, many of them use 8" × 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 PM~10~ high- or
medium-volume FRMs are not compatible with the existing PM~2.5~
networks, it creates more variability in those networks and is not as
useful as low-volume PM~10c~ FRM samples.

> ![](media/image3.wmf){width="6.230555555555555in"
> height="6.127777777777778in"}

From Chow, 1995

*Question 3: Is XRF an appropriate Pb-PM~10~ 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-α 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 PM~2.5~ FRM network uses Whatman (Hillsboro, OR) PTFE
(poltytetra fluroethylene) Teflon-membrane filters, which are 60%
thicker than those from Pall Sciences (R2PJ047, 25 µm 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 contaminated with Pb, and that compromised
study results, therefore acceptance testing of low-volume PM~10~
Teflon-membrane filters is essential before sampling (Chow, 1995). The
acceptance test should be set as 3 × MDL or 7 -- 8 ng/cm^2^. Pb analysis
by XRF is highly sensitive, without much spectral interference. It can
achieve MDLs of 1.5 -- 2 ng/cm^2^ (Note that the MDL in Table 1 of
Attachment 2 is 1.5 ng/cm^2^ and page 7 of Appendix Q to Part 50 shows
2.0 ng/cm^2^. 3 ng/cm^2^ is probably more reasonable.)

*Question 4: What other analysis methods should be considered for FRM or
FEM for the Pb-PM~10~ FRM?*

There are quite a few modern analytical methods that can be used to
quantify Pb. It can be analyzed by XRF, proton-induced X-ray emission
(PIXE), flame ionization or graphite furnace, 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 different
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 11 (sodium) 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 extensive 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 conduct spectral processing). If
archived or other samples are acquired on quartz- or cellulose-fiber
filters, other analytical technology such as AAS or ICP can be
considered, though the equivalences needs to be achieved among different
analytical methods.

**Table 1.** Minimum detectable limits (MDLs) among the different
methods.

  ------------- ---------------- ---------------- --------------- -------------- --------- -------------- -------------- --------------- --
                **Minimum                                                                                                                
                Detectable Limit                                                                                                         
                in ng/m^3\ a^**                                                                                                          

                **Flame^e,f^**   **Graphite                                                                                              
                                 Furnace^e,f^**                                                                                          

  **Species**   **INAA^b,c^**    **XRF^b^**       **PIXE^b.d^**   **AAS^e,g^**             **AAS^e,g^**   **ICP^e,g^**   **ICP-MS^h^**   

                                                                                                                                         

  Ag            0.12             6                NA^i^           4                        0.005          1              0.000090        

  Al            24               5                12              30                       0.01           20             0.004098        

  As            0.2              0.8              1               100                      0.2            50             0.000081        

  Au            NA               2                NA              21                       0.1            2.1            0.010000        

  Ba            6                25               NA              8^f^                     0.04           0.05           0.000261        

                                                                                                                                         

  Be            NA               NA               NA              2^f^                     0.05           0.06           0.000400        

  Br            0.4              0.5              1               NA                       NA             NA             NA              

  Ca            94               2                4               1^f^                     0.05           0.04           0.012675        

  Cd            4                6                NA              1                        0.003          0.4            0.000007        

  Ce            0.06             NA               NA              NA                       NA             52             0.000003        

                                                                                                                                         

  Cl            5                5                8               NA                       NA             NA             NA              

  Co            0.02             0.4              NA              6^f^                     0.02           1              0.000006        

  Cr            0.2              1                2               2                        0.01           2              0.003906        

  Cs            0.03             NA               NA              NA                       NA             NA             0.000015        

  Cu            30               0.5              1               4                        0.02           0.3            0.001061        

                                                                                                                                         

  Eu            0.006            NA               NA              21                       NA             0.08           0.000004        

  Fe            4                0.7              2               4                        0.02           0.5            0.015601        

  Ga            0.5              0.9              1               52                       NA             42             0.000039        

  Hf            0.01             NA               NA              2,000                    NA             16             0.000010        

  Hg            NA               1                NA              500                      21             26             0.010000        

                                                                                                                                         

  I             1                NA               NA              NA                       NA             NA             NA              

  In            0.006            6                NA              31                       NA             63             0.000009        

  K             24               3                5               2^f^                     0.02           NA             0.007467        

  La            0.05             30               NA              2,000                    NA             10             0.000003        

  Mg            300              NA               20              0.3                      0.004          0.02           0.001633        

                                                                                                                                         

  Mn            0.12             0.8              2               1                        0.01           0.1            0.000102        

  Mo            NA               1                5               31                       0.02           5              0.000190        

  Na            2                NA               60                             0.2^f^    \< 0.05        NA             0.008134        

  Ni            NA               0.4              1                              5         0.1            2              0.000301        

  P             NA               3                8                              100,000   40             50             NA              

                                                                                                                                         

  Pb            NA               1                3                              10        0.05           10             0.000069        

  Pd            NA               5                NA                             10        NA             42             0.000024        

  Rb            6                0.5              2                              NA        NA             NA             0.000049        

  S             6,000            2                8                              NA        NA             10             0.002621        

  Sb            0.06             9                NA                             31        0.2            31             0.000080        

                                                                                                                                         

  Sc            0.001            NA               NA                             50        NA             0.06           NA              

  Se            0.06             0.6              1                              100       0.5            25             0.000151        

  Si            NA               3                9                              85        0.1            3              NA              

  Sm            0.01             NA               NA                             2,000     NA             52             0.000006        

  Sn            NA               8                NA                             31        0.2            21             0.000076        

                                                                                                                                         

  Sr            18               0.5              2                              4         0.2            0.03           0.000035        
  ------------- ---------------- ---------------- --------------- -------------- --------- -------------- -------------- --------------- --

**Table 1.** Continued.

  ------------- ------ ---------------- ---------------- --------------- -------------- -------------- -------------- --------------- ---------- --
                       **Minimum                                                                                                                 
                       Detection Limit                                                                                                           
                       in ng/m^3\ a^**                                                                                                           

                       **Flame^e,f^**   **Graphite                                                                                               
                                        Furnace^e,f^**                                                                                           

  **Species**          **INAA^b,c^**    **XRF^b^**       **PIXE^b.d^**   **AAS^e,g^**   **AAS^e,g^**   **ICP^e,g^**   **ICP-MS^j^**              

  Ta            0.02                    NA               NA              2,000          NA             26                             0.000576   

  Th            0.01                    NA               NA              NA             NA             63                             0.000004   

  Ti            65                      2                3               95             NA             0.3                            0.001016   

  Tl            NA                      1                NA              21             0.1            42                             0.000148   

                                                                                                                                                 

  U             NA                      1                NA              25,000         NA             21                             0.000004   

  V             0.6                     1                3               52             0.2            0.7                            0.000030   

  W             0.2                     NA               NA              1,000          NA             31                             0.000187   

  Y             NA                      0.6              NA              300            NA             0.1                            0.000020   

  Zn            3                       0.5              1               1              0.001          1                              0.003051   

  Zr            NA                      0.8              3               1,000          NA             0.6                            0.000306   
  ------------- ------ ---------------- ---------------- --------------- -------------- -------------- -------------- --------------- ---------- --

^a^ Minimum detection limit is three times the standard deviation of the
blank for a filter of 1 mg/cm^2^ areal 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.

^b^ Concentration is based on 13.8 cm^2^ deposit area for a 47 mm filter
substrate, with a nominal flow rate of 20 L/min for 24-hour samples.

^c^ Olmez, 1989.

^d^ Cahill, 1980.

^e^ 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.

^f^ Fernandez, 1989.

^g^ Harman, 1989.

^h^ 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.

^i^ Not available.

*Question 5:* *Have we selected appropriate precision, bias, and method
detection limit requirements 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 accuracy, 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).

**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-PM~10~ monitoring 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 PM~10~
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 influences
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 threshold?*

Assuming the worst-case shown in Figure 2 of Attachment 1, Pb-TSP is 2.2
times Pb-PM~10~ for Pb-PM~10~ NAAQS. This translates current 1.5 µg
Pb-TSP NAAQS to 0.68 µg/m^3^ of Pb-PM~10~. This value corresponds to
median and maximum values of 0.3 µg/m^3^ and 0.7 µg/m^3^ 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 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?*

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 monitoring 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 Helena 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 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 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?*

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 µg/m^3^; it is not clear how close the five selected sites are to
roadways or other Pb emitters. Unless EPA is considering a Pb-PM~10~
NAAQS of [\<]{.underline}0.1 µg/m^3^, roadside measurements may not be a
priority. Some roadside (hot spot) monitors should be part of the normal
PM~10~ and PM~2.5~ networks, but it should not be necessary to perform
these measurements in every city, although special studies can be
conducted at busy intersections to address the spatial and temporal
variations of Pb-PM~10~ along with ultrafine particles (d~p~ \< 0.1 µm)
measurements to address the issue of human exposure and potential health
impacts (Biswas and Wu, 2005; Chow et al., 2005).

*Question 6: Under what conditions would it be appropriate to waive the
monitoring requirements 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 Frequency 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. Industry expressed a concern that the monthly maximum
form of NAAQS would require longer-term average Pb-TSP as low as 0.41
µg/m^3^ to keep the maximum monthly below 1.5 µg/m^3^. 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 be
used, EPA would need to have a minimum of every third day sampling
(i.e., ten samples/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? lf so, at what percent of the Pb
NAAQS?*

No. Areas with high Pb concentrations should keep at least an every
third day sampling schedule, 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
meteorological conditions that enhance dust suspension.

**References**

Bachmann, J.D. (2007). 2007 Critical review - Will the circle be
unbroken: A history of the U.S. National Ambient Air Quality Standards.
*J. Air Waste Manage. Assoc.*, **57**(6):652-697.

Biswas, P.; and Wu, C.Y. (2005). 2005 Critical Review: Nanoparticles and
the environment. *J. Air Waste Manage. Assoc.*, **55**(6):708-746.

Blanchard, G.E.; and Romano, D.J. (1978). High volume sampling:
Evaluation of an inverted sampler for ambient TSP measurement. *J. Air
Poll. Control Assoc.*, **28**(11):1142-1145.

Bruckman, L.; and Rubino, R.A. (1976). High volume sampling: errors
incurred during passive deposition exposure periods. *J. Air Poll.
Control Assoc.*, **26**(9):881-883.

Cahill, T.A. (1980). Proton microprobes and particle-induced x-ray
analytical systems. *Ann. Rev. Nucl. and Part. Sci.*, **30**:211-252.

Chahal, H.S.; and Romano, D.J. (1976). High Volume Sampling: Evaluation
of an Inverted Sampler for Ambient TSP Measurements. *J. Air Poll.
Control Assoc.*, **26**:895.

Chow, J.C. (1995). Critical review: Measurement methods to determine
compliance with ambient air quality standards for suspended particles.
*J. Air Waste Manage. Assoc.*, **45**(5):320-382.

Chow, J.C.; Watson, J.G.; Green, M.C.; Lowenthal, D.H.; DuBois, D.W.;
Kohl, S.D.; Egami, R.T.; Gillies, J.A.; Rogers, C.F.; Frazier, C.A.; and
Cates, W. (1999). Middle- and neighborhood-scale variations of PM~10~
source contributions in Las Vegas, Nevada. *J. Air Waste Manage.
Assoc.*, **49**(6):641-654.

Chow, J.C.; Engelbrecht, J.P.; Freeman, N.C.G.; Hashim, J.H.; Jantunen,
M.; Michaud, J.P.; de Tejada, S.S.; Watson, J.G.; Wei, F.S.; Wilson,
W.E.; Yasuno, M.; and Zhu, T. (2002). Chapter one: exposure
measurements. *Chemosphere*, **49**(9):873-901.

Chow, J.C.; Watson, J.G.; Savage, N.; Solomon, J.; Cheng, Y.S.; McMurry,
P.H.; Corey, L.M.; Bruce, G.M.; Pleus, R.C.; Biswas, P.; and Wu, C.Y.
(2005). 2005 Critical review discussion: Nanoparticles and the
environment. *J. Air Waste Manage. Assoc.*, **55**(10):1411-1417.

Federal Register, F.R. (1975). National Primary and Secondary Ambient
Air Quality Standards. Appendix B - Reference Method for the
Determination of Suspended. *CFR*, **40**(50):12-16.

Fernandez, F.J. (1989). Atomic absorption spectroscopy. In *Methods of
Air Sampling and Analysis,* 3 ed., J.P. Lodge, Jr., Ed. Lewis
Publishers, Chelsea, MI, pp. 83-89.

Harman, J.N. (1989). Inductively coupled plasma emission spectroscopy.
In *Methods of Air Sampling and Analysis,* 3rd ed., J.P. Lodge, Ed.
Lewis Publishers, Chelsea, MI, pp. 88-92.

Kitman, J.L. (2000). The secret history of lead: Special report. *The
Nation*, (March):11-45. http://www.thenation.com/doc/20000320/kitman.

Mathai, C.V.; Rogers, C.F.; and Watson, J.G. (1984). Intercomparison of
aerosol samplers used in the SCENES Program: test program protocols.
Report No. AV-R-84/534. Prepared for Electric Power Research Institute,
Palo Alto, CA, by AeroVironment, Inc., Pasadena, CA.

McFarland, A.R.; Ortiz, C.A.; and Rodes, C.E. (1980). Characterization
of sampling systems. In *Proceedings, The Technical Basis for A Size
Specific Particulate Standard, Part I & II*, C. Cowherd, Ed. Air
Pollution Control Association, Pittsburgh, PA, pp. 59-76.

Olmez, I. (1989). Instrumental neutron activation analysis of
atmospheric particulate matter. In *Methods of Air Sampling and
Analysis,* 3rd ed., J.P. Lodge, Ed. Lewis Publishers, Chelsea, MI, pp.
143-150.

Root, R.A. (2000). Lead loading of urban streets by motor vehicle wheel
weights. *Environ. Health Perspect.*, **108**(10):937-940.

Scheffe, R.; Hubbell, B.J.; Fox, T.D.; Rao, V.B.; and Pennell, W.R.
(2007). The Rationale for a Multipollutant, Multimeda Air Quality
Management Framework. *EM*, **May**:14-20.

Swinford, R.L. (1980). The assessment of passive loading effects on TSP
measurements in attainment areas. *J. Air Poll. Control Assoc.*,
**30**(12):1322-1324.

U.S.EPA (1978). National ambient air quality standard for lead. *Federal
Register*, **143**(194):46246.

U.S.EPA (2003). National air quality and emissions trends report: 2003
special studies edition. Report No. EPA 454/R-03-005. Prepared by U.S.
Environmental Protection Agency, Research Triangle Park, NC.
<http://www.epa.gov/air/airtrends/aqtrnd03/toc.html>.

U.S.EPA (2005). U.S. EPA's Final Draft National Ambient Air Monitoring
Strategy. Report No. EPA-SAB-CASAC-05-006. Prepared by U.S.
Environmental Protection Agency, Research Triangle Park, NC.
<http://www.epa.gov/ttn/amtic/monitor.html>.

U.S.EPA (2007). Report on the environment: Science report. Report No.
EPA/600/R-07/045. Prepared by U.S. Environmental Protection Agency
Office of Research and Development, Research Triangle Park, NC.

Watson, J.G.; and Chow, J.C. (1993). Ambient air sampling. In *Aerosol
Measurement: Principles, Techniques and Applications*, K. Willeke and
P.A. Baron, Eds. Van Nostrand, Reinhold, New York, NY, pp. 622-639.

Watson, J.G.; Chow, J.C.; DuBois, D.W.; Green, M.C.; Frank, N.H.; and
Pitchford, M.L. (1997). Guidance for network design and optimal site
exposure for PM~2.5~ and PM~10~. Report No. EPA-454/R-99-022. Prepared
by U.S. Environmental Protection Agency, Research Triangle Park, NC.
http://www.epa.gov/ttn/amtic/pmstg.html.

Watson, J.G.; Chow, J.C.; and Frazier, C.A. (1999). X-ray fluorescence
analysis of ambient air samples. In *Elemental Analysis of Airborne
Particles, Vol. 1*, S. Landsberger and M. Creatchman, Eds. Gordon and
Breach Science, Amsterdam, pp. 67-96.

Watson, J.G.; and Chow, J.C. (2001). Ambient air sampling. In *Aerosol
Measurement: Principles, Techniques, and Applications, Second Edition,*
2nd ed., P. Baron and K. Willeke, Eds. John Wiley & Sons, New York, NY,
pp. 821-844.

Watson, J.G.; and Chow, J.C. (2002). Comparison and evaluation of
in-situ and filter carbon measurements at the Fresno Supersite. *J.
Geophys. Res.*, **107**(D21):ICC 3-1-ICC 3-15.

Watson, J.G.; Chow, J.C.; Chen, L.-W.A.; and Kohl, S.D. (2007).
Non-Destructive XRF and SEM Analyses on Beta Attenuation Filters for
Elemental Concentrations at the Craig Road Monitor. Prepared for Clark
County Department of Air Quality and Environmental Management, Las
Vegas, NV, by Desert Research Institute, Reno, NV.

Wedding, J.B.; McFarland, A.R.; and Cermak, J.E. (1977). Large particle
collection characteristics of ambient aerosol samplers. *Enivron. Sci.
Technol.*, **11**(4):387-390.

**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 implementation 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 comments 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 specific aspects of the challenges involved
including:

1\) The importance and apparent lack of timeliness in implementation of
some of EPA's responsibilities 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
\[Pb in Total Suspended Particulate Matter (TSP)\] to Pb in PM10, 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 environmental 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.

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 renewed 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 worthy 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,
Consultation, 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-PM10" by Joann Rice.

3)  "Lead NAAQS Ambient Air Monitoring Network: Network Design Options
    Under Consideration" 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 reference and federal equivalence methods of analysis, and both
network design and sampling frequency 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 evaluation by our CASAC Ambient
Air Monitoring Subcommittee.

We hope this kind of thorough and positive responsiveness will be
followed by similar consideration 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.

**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 Ambient Air Quality Standard (NAAQS). I appreciate the
opportunity to comment during this intermediate 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 offer comments on several aspects that need
further attention. My comments address the consultation 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 implementing 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, integration with other measurement systems, and
    usefulness as the measurement system for the indicator, please
    describe the advantages and disadvantages of sampling and analysis
    of Pb-TSP versus sampling and analysis of Pb-PM10.*

> 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 effects through ingestion by multi-media
> routes would be ignored. Also, there would be a disconnect 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 networks (e.g., HiVol PM10, TSP Total Metals). The
> California Air Resources Board has a 20-site Toxics Network (12 lpm
> TSP, Teflon filter, ICP/MS analysis) that we would like to see
> considered as an option for meeting compliance requirements. By taking
> advantage of existing 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.

2.  *Is it appropriate to monitor for Pb-PMl0 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-PM10 levels are about half
> of Pb-TSP levels.

3.  *One indicator option suggests using 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?*

> From Figures 1 and 2, Pb-PM10 to Pb-TSP correlations seem relatively
> high, but further collocated monitoring and analysis would strengthen
> the analysis.

4.  *We have limited collocated Pb-PM10 and Pb-TSP monitoring data. What
    types and "scaling factors" 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?*

> 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-PM10)

1.  *Is it appropriate to use the low-volume PM10coarse FRM sampler as
    the Pb-PM10 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
> PMl0coarse FRM sampler is reasonable.

2.  *What other PMl0 samplers should be considered as either FRM or FEM
    for the Pb-PMl0 FRM?*

> SLT entities should be permitted to use the HiVol TSP and all existing
> FRM and FEM PM10 samplers. Even if the Pb NAAQS goes from TSP to PM10,
> TSP would be a conservative (i.e., health-protective) measurement.

3.  *Is XRF an appropriate Pb-PM10 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-PM10 FRM?*

> AAS, ICP/MS, and PIXIE.

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 reasonable, as well as the proposed requirement that the
> MDL must be equal to or less than 1/10^th^ 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 oriented 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, population and near roadway monitors
> should be considered.

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 is reasonable, but the issue of periodically emitting
> sources should be considered, which would lower the 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?*

> 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., population, 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 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?*

> Unless the Pb NAAQS is very low, near roadway exposures should not be
> a problem, as shown in Table 7.

6.  *Under what conditions would it be appropriate to waive the
    monitoring requirements for either 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 average?*

> The California Air Resources Board has had a monthly average Pb-TSP
> standard (not to be exceeded) of 1.5 μg/m^3^ 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 percent 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? lf so, at what percent of the Pb
    NAAQS?*

> No, as that would be unprecedented for criteria pollutant and not
> health protective for periodic sources.

**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 determination 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 conducted 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 sampling and analysis of
Pb-TSP versus sampling and analysis of Pb-PM~10~.*

*Question 2: Is it appropriate to monitor for Pb-PM~10~ near Pb sources?
And if so, under what conditions?*

*Question 3: One indicator option suggests using scaling Pb-PM~10~
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?*

The advantages of using a Pb-PM~10~ based monitoring system for the Pb
ambient air quality standard lies in the greatly improved precision and
better definition of what is being monitored. 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 obtained 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 ambient 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 major 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 the proposed Pb-PM~10~ 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 ½ 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 micron 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 PM~10~ 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 particle concentrations and composition from a
near-by smelter source. In addition, insufficient detail 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 standard 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-PM~10~ 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.

**Mr. Dirk Felton**

**Dirk Felton: CASAC AAMM Individual Written Comments on\
Ambient Air Monitoring Options for Lead**

(Prepared for the March 25^th^ 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, sampler technical specifications and
analytical methods. More specific comments can be offered 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 available 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 PM~10~ and PM~2.5~ samplers in New York City and Niagara
Falls, NY. The data for Pb is displayed in table 1 as ratios of PM~10~**
/ **PMcoarse.**

> Table 1

  -------------- --------------- -------------------- --------------------
  **NYC**        All Data        Cold Months          Warm Months

  **mean**       0.47            0.41                 0.53

  **median**     0.47            0.43                 0.61

  **25%ile**     0.29            0.23                 0.33

  **75%ile**     0.66            0.61                 0.71

  **min**        0.00            0.00                 0.00

  **max**        1.00            0.93                 1.00
  -------------- --------------- -------------------- --------------------

  -------------- --------------- -------------------- --------------------
  **Nia Falls**  All Data        Cold Months          Warm Months

  **mean**       0.31            0.27                 0.34

  **median**     0.27            0.29                 0.24

  **25%ile**     0.08            0.06                 0.12

  **75%ile**     0.47            0.46                 0.53

  **min**        0.00            0.00                 0.00

  **max**        1.00            0.58                 1.00
  -------------- --------------- -------------------- --------------------

**The data shows that for the Pb containing particles smaller than
PM~10~, slightly more Pb is found in the PM~2.5~ 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 Monitoring Conference. The .ppt file can be found on the EPA
AMTIC webpage:**

<http://www.epa.gov/ttn/amtic/files/ambient/2006conference/felton.pdf>

• **[Attachment 1 *Options for Lead NAAQS Indicator: Monitoring
Implications *]{.underline}Charge Questions:**

*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 sampling and analysis of Pb-TSP versus
sampling and analysis of Pb-PM~10~.*

> **The primary advantage of implementing the PM~10~ 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-PM~10~ 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 smelters and other smaller sources where
> significant outdoor raw material handling is performed. It is
> acceptable to use PM~10~ monitors at middle or neighborhood scale
> population exposure locations adjacent to source properties. The data
> from the PM~10~ 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 related to
> sources.**

*3. One indicator option suggests using scaling Pb-PM~10~ 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?*

> **Scaling PM~10~ data is not necessary. Sites that are distant from
> sources of Pb are not going to be significantly impacted by particles
> larger than PM~10~. One way to determine 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 concentration variation are not likely to be impacted
> by large particles. (See the upwind site data in Figure1.)**

(Figure 1)

**NY Source Related High Vol TSP Lead Monitoring (2006)**

![](media/image4.jpeg){width="6.089583333333334in" height="2.45625in"}

1/5/06 2/10/06 3/18/06 4/23/06 5/29/06 7/4/06 8/9/06 9/14/06 10/20/06
11/25/06 12/31/0

![](media/image5.jpeg){width="2.5840277777777776in" height="0.2in"}

• **[Attachment 2 *Draft Federal Reference Method (FRM) and Federal
Equivalent Method (FEM) Criteria for Lead in PM10 (Pb- PM~10~)
*]{.underline}**

> **Charge Questions:**

*1. Is it appropriate to use the low-volume PM~10~ FRM sampler as the
Pb-PM~10~ FRM sampler?*

> **Yes, the sampler is well characterized and very familiar to State
> and Local air monitoring Agencies. The sequential versions of the
> samplers should also be designated as FRMs because future Pb PM~10~
> 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
> (midnight to midnight) and filter handling procedures as followed by
> the majority of the data providers for the national network.**

*2. What other PM~10~ samplers should be considered as either FRM or FEM
for the Pb-PM~10~ FRM?*

> **Monitoring Agencies should be permitted to use High Volume TSP and
> existing High Volume FRM and FEM PM~10~ samplers if the data is
> approximately adjusted for Local Conditions and the data from the site
> is well below the ambient Pb standard (\< 70% of the NAAQS). If TSP
> samplers are used, the resulting Pb concentrations should be compared
> to a new Pb-PM~10~ standard. High Volume samplers would have to be
> considered FEMs.**

*3. Is XRF an appropriate Pb-PM~10~ FRM analysis method?*

> **Specifying XRF would make analytical problems stemming from
> non-uniform loading and non-ideal filter loading densities an inherent
> part of the FRM. ICPMS 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-PM~10~ 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 *Lead NAAQS Ambient Air Monitoring Network: Network
Design Options Under Consideration *]{.underline}**

> **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
> incinerator 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 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?*

> **Urban areas are likely to show a small increment to the background
> Pb concentrations associated with known sources. Since these
> increments are not significant at 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 ambient 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)

**2006 High Vol TSP Lead Data**

![](media/image6.jpeg){width="6.107638888888889in"
height="2.466666666666667in"}

1/5/06 2/10/06 3/18/06 4/23/06 5/29/06 7/4/06 8/9/06 9/14/06 10/20/06
11/25/06 12/31/0

![](media/image7.jpeg){width="1.8166666666666667in"
height="0.20277777777777778in"}

*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 discontinued 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 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?*

> **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 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 supervised representative Pb monitoring and that monitoring
> data shows no short term concentration spikes and no incremental
> differences in the downwind Pb concentration.**
>
> **Required non-source oriented monitors should be waived if the design
> value is below 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 monitoring 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 *]{.underline}**

> **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 below 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.**

*3. Is it appropriate to relax the sampling frequency in areas
considerably higher than the NAAQS? lf so, at what percent of the Pb
NAAQS?*

> **No, Pb concentration data from areas above the NAAQS are necessary
> to adequately determine the potential health effects from specific Pb
> sources.**

**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 obtain 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
monitoring program needs to address this issue. Exposure to the
population as a whole is much less important 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 of Pb-TSP versus sampling and
analysis of Pb-PM~10~?*

The main advantage I can see is that the PM10 would provide lower costs
and ease of implementation. 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 technology that provides good flow control and insensitivity
to wind direction. There remains a problem 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-PM~10~ near Pb sources? And if so,
under what conditions?*

Only if you are going to a PM10-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- PM~10~ 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?*

It is always risky to "scale" data when it is possible to directly
measure a quantity of interest.

*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 oriented)? What levels are
appropriate for the types of scaling factors identified in the white
paper?*

If we set a stringent standard level, then the values will be so
dominated by noise and the development 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 PM10c FRM sampler as the
Pb-PM~10~ FRM sampler? What other PM~10~ samplers should be considered
as either FRM or FEM for the Pb-PM~10~ FRM?*

Sure. The PM10c 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 because 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 µm at
10 µm to something more like + 0.1 to 0.2 µm. Then FEMs would have good
precision in side-by-side comparisons with the PM10c sampler.

*Is XRF an appropriate Pb-PM~10~ FRM analysis method?*

Yes, there can be problems in areas with significant As concentrations
since there is an overlap in the As Kα with one of the Pb l-lines.

*What other analysis methods should be considered for FRM or FEM for the
Pb-PM~10~ FRM?*

ICP/MS or GFAAS would both provide the sensitivity and precision.
Electrochemical methods 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.

*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
measurements 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. 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 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 requirement 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 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?*

*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 average?*

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.

*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 possible 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 development 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 improvements being made. Thus, I cannot see
any reason why one would want to reduce the measurement frequency.

**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 concentrations. 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 scaler for
the number of source-oriented monitoring sites makes sense. An
alternative metric for scaling the number of monitors is the
population-weighed exposure. This would require more monitors for those
sources that result in higher population exposure.

Population-oriented monitors would require more consideration. In
particular, it would be helpful 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.

**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]{.underline}: The range of "candidate NAAQS level"
shown in these tables (0.02 to the current 1.5 µg/m^3^) is quite wide (I
understand that the Staff Paper recommends no higher than 0.2 µg/m^3^).
It may be important to compare the extent of uncertainty associated with
the reported exposure/health effects relationships and the estimated
uncertainty associated with Pb monitoring network design.

**• "Options for Lead NAAQS Indicator: Monitoring Implications"**

*Q1. 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 sampling and analysis of Pb-TSP versus
sampling and analysis of Pb-PM10.*

[Advantages]{.underline}: The better precision and ability to
accommodate sequential sampling in case more frequent sampling (i.e.,
every 3^rd^ day) is required.

[Disadvantages]{.underline}: Possible requirement for "scaling factor"
to adjust for larger particles that the Pb-PM~10~ sampler may miss.

*Q2. Is it appropriate to monitor for Pb-PM10 near Pb sources? And if
so, under what conditions?*

Figure 2 on page 7 indicates a good linear relationship. This suggests
that Pb-PM~10~ works in source-oriented situations, but I think more
data (pilot studies?) are needed to more fully characterize the factors
(e.g., size distribution, wind-direction dependency, etc.) that affect
comparability between Pb-TSP and Pb-PM~10~ samplers.

*Q3. One indicator option suggests using 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?*

The source oriented sites' data (Figure 2) support justification for
scaling factor using the relatively 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-PM~10~ monitors.

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, I 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
different sites (mixed effects model).

**• "Draft Federal Reference Method (FRM) and Federal Equivalent Method
(FEM) Criteria for Lead in PM10 (Pb- PM10)"**

*Q1. Is it appropriate to use the low-volume PM10c FRM sampler as the
Pb-PM10 FRM sampler?*

It seems reasonable given the better precision than the Pb-TSP sampler.

*Q2. What other PM10 samplers should be considered as either FRM or FEM
for the Pb-*

*PM10 FRM?*

I don't know.

*Q3. Is XRF an appropriate Pb-PM10 FRM analysis method?*

It sounds reasonable based on the required characteristics. It is also
comparable with the PM~2.5~ and PMc speciation monitor data. During the
conference call, Dr. Phil Hopke mentioned possibility 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-PM10*

*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 Consideration"**

*Q1. What types of monitoring sites should be emphasized in the network
design (e.g., source oriented monitors, population monitors, near
roadway monitors)?*

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 oriented 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 surrounded
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 PM~2.5~ monitors in
comparison to Pb a bit unconvincing - the levels of ozone and PM~2.5~
would be fairly uniform within a city because 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 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?*

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
µg/m^3^ or less. Given the range of variability in the
concentration-to-emission ratios (Table 2), an initial site-specific
surveillance may be required to determine if monitoring is needed in
that location.

*Q3. 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?*

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 monitoring
requirements on (e.g., population, design value) ?*

\(1\) Population size; (2) existing data indicating Pb concentrations
higher than "background" levels.

*Q5. 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?*

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 ambient Pb concentrations.

**• "Lead NAAQS Ambient Air Monitoring Network: Sampling Frequency
Options Under Consideration"**

*Q1. What sampling frequency would be appropriate if the Pb NAAQS is
based on a monthly average?*

Every-3^rd^-day sampling appears appropriate if the Pb-PM~10~ 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-6^th^-day part of the every-3^rd^-day data in pilot study and
check if the precision is sufficient for DQO. If it is, then allow the
sampling frequency to be every-6^th^-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? lf so, at what percent of the Pb
NAAQS?*

It is hard to comment on this without actually looking at data.

**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 Implications: *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
    sampling and analysis of Pb-TSP versus sampling and analysis of
    Pb-PM10.*

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
sequential 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-PM10 near Pb sources? And if so,
under what conditions?*

Yes, it is appropriate to monitor for Pb-PM10 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-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?*

I don't think the data should be scaled, I think the standard should be
set for Pb-PM10 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-PM10---Pb-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-P10 and Pb-TSP monitoring data. What
types and*

*"scaling factors" 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?*

It would be helpful to see the Pb-PM10---Pb-TSP relationship for a
variety of sources and monitor 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 characterize 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-PM10
FRM sampler?*

Yes.

*What other PM10 samplers should be considered as either FRM or FEM for
the Pb-PM10 FRM?*

EPA should consider allowing TSP monitors to be compared to the Pb-PM10
NAAQS when (unadjusted) values are below the new Pb-PM10 standard. This
would be conservative -- concentrations 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-PM10 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
determination 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-PM10 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. 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., population, design value)?*

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 typical non-source concentrations in urban and rural
environments.

*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?*

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 comprehensive 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 average?*

*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? lf 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
requirement. The 30% figure proposed was fine. I'm not sure I see the
rationale to relaxing frequency in areas above the NAAQS. Presumably
there will be actions taken to reduce concentrations, which we would
want to document with measured values, and particularly with improved
precision as we approach the standard.

**Dr. Armistead (Ted) Russell**

CASAC AAMM Ambient Air Lead Monitoring Lead

Armistead Russell

(Prepared for the March 25^th^ 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 monitor, 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 NAAQS Indicator: Monitoring
Implications]{.underline}*

*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 sampling and analysis of Pb-TSP versus
sampling and analysis of Pb-PM~10~.*

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-PM~10~ near Pb sources? And if
so, under what conditions?*

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
population. 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-PM~10~ 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?*

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.

*[Draft Federal Reference Method (FRM) and Federal Equivalent Method
(FEM) Criteria for Lead in PM10 (Pb-PM~10~)]{.underline}*

*1. Is it appropriate to use the low-volume PM~10c~ FRM sampler as the
Pb-PM~10~ 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 PM~10~ samplers should be considered as either FRM or FEM
for the Pb-PM~10~ FRM?*

*3. Is XRF an appropriate Pb-PM~10~ 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 specified 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-PM~10~ 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 requirements for FEM evaluation?*.

This depends, in part, on the form of the standard (the longer the
averaging, the less precision is needed). The levels provided appear
reasonable.

*[Lead NAAQS Ambient Air Monitoring Network: Network Design Options
Under Consideration]{.underline}*

*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 monitoring, 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.

*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?*

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 standard. 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 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 either source or non-source oriented
monitors?*

*[Lead NAAQS Ambient Air Monitoring Network: Sampling Frequency Options
Under Consideration]{.underline}*

*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? lf so, at what percent of the Pb
NAAQS?*

No.

**Dr. Jay Turner**

**Draft Comments Submitted by Jay R. Turner (March 25, 2008)**

**Attachment 1: Options for Lead NAAQS Indicator: Monitoring
Implications**

[Charge Questions]{.underline}

-   *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 sampling and analysis
    of Pb-TSP versus sampling and analysis of Pb-PM~10~.*

-   *Is it appropriate to monitor for Pb-PM~10~ near Pb sources? And if
    so, under what conditions?*

-   *One indicator option suggests using scaling Pb-PM~10~ 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?*

-   *We have limited data 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 oriented)? What
    levels are appropriate for the types of scaling factors identified
    in the white paper?*

[Comments]{.underline}

Clearly Pb-PM10 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 complicated for Pb because the routes of
exposure include ingestion as well as inhalation, and thus larger
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-PM10 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-PM10 with scaling factors to assess compliance with
the Pb-TSP standard).

*Role of Pb-PM10 measurements if the indicator is Pb-TSP.* Sites with
Pb-PM10 greater than the threshold value for the Pb-TSP indicator
clearly violate the standard. Thus, Pb-PM10 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-PM10 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 presented in the memorandum,
the regression suggests negligible increase in Pb-TSP compared to
Pb-PM10 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
levels on the regression coefficients. While there were 31 sites,
virtually all of the concentration values are below 0.05 µg/m^3^. How
many of the high concentration values (e.g., greater than 0.1 µg/m^3^)
came from a single site? This would clarify whether the regression is
being strongly influenced 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 µg/m^3^). This will provide a
better visual representation of the relatively high Pb-TSP values
observed at relatively low Pb-PM10 values. For the source-oriented
analysis with only two sources, is the data above 0.5 µg/m^3^ from a
single source?

**Attachment 2: Draft Federal Reference Method (FRM) and Federal
Equivalent Method (FEM) Criteria for Lead in PM10 (Pb-PM10)**

[Charge Questions]{.underline}

-   *Is it appropriate to use the low-volume PM10c FRM sampler as the
    Pb-PM10 FRM sampler?*

-   *What other PM~10~ samplers should be considered as either FRM or
    FEM for the Pb-PM10 FRM?*

-   *Is XRF an appropriate Pb-PM10 FRM analysis method?*

-   *What other analysis methods should be considered for FRM or FEM for
    the Pb-PM10 FRM?*

-   *Have we selected appropriate precision, bias, and method detection
    limit requirements for FEM evaluation?*

[Comments]{.underline}

If a Pb-PM10 indicator is selected, the low-volume PM10c 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 Attachment 3 (0.02
µg/m^3^) and a 4:1 scaling factor for Pb-TSP compared to Pb-PM10
(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 portion of
the candidate range (0.02 -- 1.5 µg/m^3^) 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 designation, 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.

**Attachment 3: Lead NAAQS Ambient Air Monitoring Network: Network
Design Options Under Consideration**

[Charge Questions]{.underline}

-   *What types of monitoring sites should be emphasized in the network
    design (e.g., source oriented monitors, population monitors, near
    roadway monitors)?*

-   *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. 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., population, design value)?*

-   *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?*

-   *Under what conditions would it be appropriate to waive the
    monitoring requirements for either source or non-source oriented
    monitors?*

[Comments]{.underline}

Emphasis should be placed on population monitoring and source oriented
monitoring. In the latter case, it is important to consider historical
industrial activities and not rely solely on contemporary emission
inventories. For example, in East St. Louis is appears that a
significant source of Pb-PM10 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 Clayton, 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 concentrated in the Metro East area).

**Attachment 4: Lead NAAQS Ambient Air Monitoring Network: Sampling
Frequency Options Under Consideration**

[Charge Questions]{.underline}

-   *What sampling frequency would be appropriate if the Pb NAAQS is
    based on a monthly average?*

-   *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]{.underline}

It is likely that 1-in-3 day or higher frequency would be needed to
obtain a stable monthly average values. Given that the Pb will often be
associated with the coarse PM fraction and the sensitivity of coarse PM
to environmental conditions, sampling frequencies greater than 1-in-6
days will most certainly be needed in most cases.

Any thoughts on how concentration values below MDL would be imputed?

**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 of Pb-TSP versus sampling and analysis of
Pb-PM10.*

*... monitor for Pb-PM10 near Pb sources?*

*... "scaling factors"?*

*... appropriate to use the low-volume PM10 FRM sampler?*

Purely as sampling technology, the advantages of the lo-vol PM~10~
sampler over hi-vol TSP should be decisive. The PM~10~ 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 automated and already
widely deployed is no small additional virtue. As several CASAC and AAMM
commenters have already observed, a TSP-PM~10~ scaling factor is an
unnecessary distraction 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\. Selection of analysis methods:

*... XRF an appropriate Pb-PM10 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 currently in review at
ES&T reports that the routine Pb-PM~2.5~ measurements in the CSN/STN and
IMPROVE networks demonstrate XRF detection limits of 5-7 ng/cm^2^,
corresponding to air levels of \~3 ng/m^3^ for a 24h sample at 16.7 lpm.
The paper defined this as the actual Pb concentration at which 95% of
the observations detect Pb and report it to be significantly above blank
levels.

\* 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 concentrations 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 possibility
that next decade's Pb CASAC panel may find itself reviewing new evidence
of adverse effects at levels below today's contemplated NAAQS.

**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-PM~10~ is a better indicator than Pb-TSP. Although
Pb-TSP includes the contribution from larger particles, it will not
serve well as an indicator for NAAQS. The primary concern 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-PM~10~, 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 PM~10~. Very little of the PM emissions from these sources resemble
TSP. If the objective of measuring ambient Pb levels is to monitor
impacts of freshly emitted Pb, using Pb-PM~10~ 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-PM~10~ is consistent with monitoring PM~10~. It helps
streamline our monitoring efforts.

Using Pb-PM~10~ 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 PM~10~.

Because the above reasons, we should replace Pb-TSP with Pb-PM~10~.
There is no value in scaling Pb-PM~10~ 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, cadmium, 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 explicitly and not causing the confusion discussed above.

***Draft Federal Reference Method (FRM) and Federal Equivalent Method
(FEM) Criteria for Lead in PM~10~ (Pb-PM~10~)***

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 Consideration***

The third analysis in this EPA memo used the SCREEN3 model to help
establish source oriented monitoring thresholds. The SCREEN3 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 μg/m^3^ for the
current Pb NAAQS of 1.5 μg/m^3^, 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 μg/m^3^, the monitoring threshold will be 0.014
μg/m^3^. If site-specific modeling (with building downwash considered)
yields a result higher than 0.014 μg/m^3^ (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 Consideration***

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 frequency can be relaxed from 1-in-2 to 1-in-3. If the
results are only 50% of the new NAAQS, then the frequency may be further
relaxed to 1-in-6.

**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 unanimously recommended that the Agency revises the indicator for
lead sampling from TSP to PM~10~. I continue to support this
recommendation. The letter said:

> "The agency should seize this opportunity to transition from TSP to
> PM~10~, since the current review 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 indicator selected 30 years ago.\< .. \> Rather than needing
> to arduously establish a large series of site-specific PM10-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 seriously-flawed, sampler
> performance."

I do agree with this reasoning.

**Charge questions, Attachment 1, Options for Lead NAAQS Indicator:
Monitoring Implications:**

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 sampling and analysis
    of Pb-TSP versus sampling and analysis of Pb-PM10.*

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 µm particles depends greatly on a wind speed
and direction. Contrary to Pb-TSP, Pb-PM~10~ 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 PM~10~ measurements. The great
advantage of this strategy is the existing PM~10~ network and thus a
possibility of integration with other measurement systems.

2.  *Is it appropriate to monitor for Pb-PM10 near Pb sources? And if
    so, under what conditions?*

Yes, it is. Pb-PM~10~ should be monitored near the major Pb sources to
get the idea about Pb concentrations in this inhalable particle size
range. Since Pb-containing larger than 10 µm particles may be important
in the vicinity of large Pb point sources, such as Pb smelters or areas
with considerable 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-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?*

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-P10 and Pb-TSP monitoring data.
    What types and "scaling factors" 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?*

Kevin Cavender's memo from March 3, 2008 emphasizes that all size Pb
particles contribute to exposures and associated health effects. This is
true, but it does not necessary mean that the Pb-PM~10~ standard has to
be tied to Pb-TSP. As shown in this document, non-source oriented Pb-TSP
and Pb-PM~10~ monitor data (Figure 1) show strong linear relationship
and the ratio of Pb-PM~10~ to Pb- TSP close to unity. Rather than trying
to decide if Pb-TSP = Pb-PM~10~\*1.014+0.028 or +0.017, the Pb-PM~10~
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-PM~10~ is driven by the highest Pb concentrations.
If the standard is set at the level below 0.5 µg/m^3^, it is unimportant
if 1 µg/m^3^ Pb-PM~10~ concentration corresponds to 1.39 or 2.2 µg/m^3^
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 µg/m^3^) 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-PM10 FRM sampler?*

> Yes, it is.

2.  *What other PM10 samplers should be considered as either FRM or FEM
    for the Pb-PM10 FRM?*

> Low-volume, sequential PM~10~ FRM sampler is the best candidate for
> the Pb~10~ FRM.

3.  *Is XRF an appropriate Pb-PM10 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 FEM for
    the Pb-PM10 FRM?*

Modern analytical methods that can be used to quantify Pb include
graphite furnace AA, ICP/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 highest 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 µg/m^3^ per tpy is consistent with
the results obtained by the screening model. After the Pb standard is
established, 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 monitoring 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 monitoring
    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 PM~10~ monitoring
network can be utilized for this purpose. The additional analysis cost
for Pb is very reasonable, if XRF method is used. In addition, PM~2.5~
monitoring network can provide some information regarding Pb
concentrations in this PM size fraction.

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 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?*

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 µg/m^3^) these
monitors should probably be part of the non-source oriented monitoring
network.

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 1-in-6 day sampling schedule is not frequent enough. A
1-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, 1-in-3 day and
1-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 completed, it would be more obvious
which sampling frequency is sufficient. The appropriate sampling
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 1-in-6 day, if all 12 monthly averages in a calendar year
are lower than 30% of the Pb NAAQS. This seems reasonable to me,
although 50% is probably sufficient. If an area elects to stay with the
higher sampling frequency, this should be allowed.

3.  *Is it appropriate to relax the sampling frequency in areas
    considerably higher than the NAAQS? lf so, at what percent of the Pb
    NAAQS?*

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.

**Appendix C -- Agency's Background and Charge Memorandum to the**

**CASAC AAMM Subcommittee**

![](media/image1.wmf){width="1.0833333333333333in"
height="1.0291666666666666in"}

> **UNITED STATES ENVIRONMENTAL PROTECTION AGENCY**

**RESEARCH TRIANGLE PARK, NC 27711**

March 3, 2008

**[MEMORANDUM]{.underline}**

**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 Subcommittee 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 PM~10~ (Pb-PM~10~) monitors to be used in the
NAAQS surveillance monitoring network. The consultation on the draft Pb
in PM~10~ Federal Reference Method (FRM) and Federal Equivalent Method
(FEM) criteria will assist EPA in developing these methods for use in
measuring Pb in PM~10~. The consultation on network design options will
provide Subcommittee comments .and advice on how the Pb 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 exposures in large urban areas.
Finally, the consultation on sampling frequency will solicit
Subcommittee 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 consultation 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 rulemaking 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
comments 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 regard to our review of the Pb NAAQS, together with
proposed changes to the associated monitoring requirements and the draft
FRM for Pb in PM~10~. Note that due to a court order, any monitoring
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 PM~10~ 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 regarding 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 CASAC AAMM Subcommittee meeting is to
provide consultation 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 NAAQS Indicator: Monitoring
    Implications***

> **[Background and Summary]{.underline}:** Lead in total suspended
> particulate (TSP) is the current indicator for the lead NAAQS.
> Concerns have been raised regarding the quality of the data generated
> 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. CASAC has recommended that EPA move towards the use of
> Pb in PM~10~ 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 PM~10~ to be used as the indicator or to allow Pb in
> PM~10~ 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.

**[Charge Questions]{.underline}:**

> *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 sampling and analysis of
> Pb-TSP versus sampling and analysis of Pb-PM~10~.*
>
> *Is it appropriate to monitor for Pb-PM~10~ near Pb sources? And if
> so, under what conditions?*
>
> *One indicator option suggests using scaling Pb-PM~10~ 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?*
>
> *We have limited data 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 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 PM~10~ (Pb-PM~10~)***

> **[Background and Summary]{.underline}:** In order for monitoring data
> to be used in determination of attainment 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 PM~10~.
> The EPA has drafted language for a FRM for Pb in PM~10~ based on the
> existing FRM sampler for low volume PM~10c~ in Appendix 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 PM~10~. The attached document
> summarizes the rationale for the proposed changes and includes a draft
> of the FRM and FEM CFR text.
>
> **[Charge Questions]{.underline}:**
>
> *Is it appropriate to use the low-volume PM~10c~ FRM sampler as the
> Pb-PM~10~ FRM sampler?*
>
> *What other PM~10~ samplers should be considered as either FRM or FEM
> for the Pb-PM~10~ FRM?*
>
> *Is XRF an appropriate Pb-PM~10~ FRM analysis method?*
>
> *What other analysis methods should be considered for FRM or FEM for
> the Pb-PM~10~ FRM?*
>
> *Have we selected appropriate precision, bias, and method detection
> limit requirements for FEM evaluation?*

-   **Attachment 3 -- *Lead NAAQS Ambient Air Monitoring Network:
    Network Design Options Under Consideration***

> **[Background and Summary]{.underline}:** 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 reduced 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 adequate to support a
> lower Pb NAAQS. The attached document identifies a number of network
> design options under consideration.
>
> **[Charge Questions]{.underline}:**
>
> *What types of monitoring sites should be emphasized in the network
> design (e.g., source oriented monitors, population monitors, near
> roadway monitors)?*
>
> *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. 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., population, design value)?*
>
> *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?*
>
> *Under what conditions would it be appropriate to waive the monitoring
> requirements for either source or non-source oriented monitors?*

-   **Attachment 4 -- *Lead NAAQS Ambient Air Monitoring Network:
    Sampling Frequency Options Under Consideration***

> **[Background and Summary]{.underline}:** 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 1-in-6
> sampling schedule yields 15 samples per quarter on average with 100%
> completeness, 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% completeness, or
> between 3 and 5 samples with 75% completeness. If we change the
> averaging time to a monthly average, we may need to increase the
> sampling frequency to better reflect ambient Pb concentrations during
> the averaging period. The attached document describes several options
> we are considering which would increase the sampling frequency.
>
> **[Charge Questions]{.underline}:**
>
> *What sampling frequency would be appropriate if the Pb NAAQS is based
> on a monthly average?*
>
> *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