stipulate and highlight monitoring and data considerations. New section
2.0 would include statistical requirements for spatial averaging (which
is part of the form of the current and proposed annual standard for
PM2.5). As explained in section II.F.2 above, we are
proposing to tighten the constraints on use of spatial averaging to
reflect enhanced knowledge of typical monitor correlation coefficients
in metropolitan areas. As also set out in section II.F.2, the
Administrator is further soliciting comment on the other staff-
recommended alternative of revising the form of the annual
PM2.5 standard to one based on the highest community-
oriented monitor in an area, with no allowance for spatial averaging.
    New section 3.0 would codify aspects of raw data reporting and raw
data time interval aggregation including specifications of number of
decimal places. Previously, these reporting instructions resided only
in associated guidance documents. Section 3.0 would also note the
process for assimilating monitored concentration data from collocated
instruments into a single ``site'' record; data for the site record
would originate mainly from the designated ``primary'' monitor at the
site location, but would be augmented with collocated Federal reference
method (FRM) or Federal equivalent method (FEM) monitor data whenever
valid data are not generated by the primary monitor. This procedure
would enhance the opportunity for sites to meet data completeness
requirements. This proposed language likewise would codify existing
practice, since the technique was previously documented in guidance
documentation and implemented as EPA standard operating procedure.
3. PM2.5 Computations and Data Handling Conventions
    The EPA is proposing a spatially-averaged annual mean as the form
of the annual PM2.5 standard and a 98th percentile
concentration as the form of the 24-hour PM2.5 standard.
Although no actual computational change is proposed for a spatially-
averaged annual mean, the proposed Appendix N now differentiates, in
language and formulae, between a spatial average of more than one site
and a spatial average of only one site. The intent of this change is to
alleviate confusion caused by the current ``catch-all'' generic
reference. The proposed revisions to appendix N would identify the
NAAQS metrics and explain data capture requirements and comparisons to
the standards for the annual PM2.5 standard and the 24-hour
standard (in sections 4.1, and 4.2, respectively); data rounding
conventions (in section 4.3); and formulas for calculating the annual
and 24-hour metrics (in sections 4.4 and 4.5, respectively).
    With regard to the annual PM2.5 standard, we are
proposing to retain current data capture requirements for the annual
standard with two exceptions. Current appendix N has reduced data
capture requirements for years that exceed the level of the annual
NAAQS; specifically, a minimum of 11 valid samples per quarter as
opposed to a more stringent 75 percent (of scheduled samples) is
currently considered sufficient in those instances where the annual
mean exceeded the NAAQS level. See existing Part 50 App.

N 2.1(b). The EPA is proposing to also allow 11 or more samples per
quarter as an acceptable minimum if the calculated annual standard
design value exceeds the level of the standard. The EPA solicits
comments on this proposed change.
    A second proposed change in the data completeness requirements
would incorporate data substitution logic for situations where the
proposed 11 sample per quarter minimum is not met. Consistent with
existing guidance and practice (implementing current App. N 2.1(c)),
EPA proposes to incorporate the following requirement into appendix N:
a quarter with less than 11 samples would be complete and valid if, by
substituting a historically low 24-hr value for the missing samples (up
to the 11 minimum), the results yield an annual mean, spatially
averaged annual mean, and/or annual standard design value that exceeds
the levels of the standard. The EPA proposes to implement this
procedure for making comparisons to the NAAQS and not to permanently
alter the reported data. The EPA considers this a very conservative
means of inputing data (and increasing the opportunities for using
monitoring data that otherwise are valid), but solicits comment on the
proposed approach.
    With regard to the 24-hour PM2.5 standard, the proposed
revisions to appendix N would include a special formula (Equation 6 in
the proposed rule) for computing annual 98th percentile values when a
site operates on an approved seasonal sampling schedule. This formula
was previously stated only in guidance documentation (``Guideline on
Data Handling Conventions for the PM NAAQS'', April 1999) but was
utilized, where appropriate, in official OAQPS design value
calculations. Seasonal sampling has traditionally been implemented in
periods that do not divide months; this criterion is explicitly stated
in the proposed amendments.
    The proposed revisions to appendix N would also incorporate
language explicitly stating that 98th percentiles (for both regular and
seasonal sampling schedules) is to be based on the applicable number of
samples rather than the actual number of samples. Both annual 98th
percentile equations (proposed Equations 5 and 6) would now reflect
this approach. To accommodate seasonal sampling, the calculation of
``annual applicable number of samples'' would be changed from the sum
of the ``quarterly applicable number of samples'' to a sum of the
``monthly applicable number of samples''. The EPA welcomes comment on
the ``applicable number of samples'' concept and calculation.
    To simplify the regulatory language, another proposed change to
appendix N would eliminate the equation computational examples. The EPA
will provide extensive computational examples in forthcoming guidance
documents.
4. Secondary Standard
    The EPA is proposing that the secondary standards for
PM2.5 be the same as the primary standards. However, the
Administrator is soliciting comment on the alternative of a distinct 4-
hour secondary standard for visibility protection with a form of an
annual percentile, in the range 92nd to 98th, for a 12 p.m. to 4 p.m.
local standard time daily average, averaged over 3 years. The same
basic data handling approach as used for the 24-hour 98th percentile
primary standard would also be utilized for a 4-hour percentile-based
secondary standard (should EPA ultimately adopt such a standard). For
example, 75 percent of the hours in the averaging time (i.e., 3 hours)
would be required to produce a valid daily measurement. Also, 75
percent capture of sample days in a quarter would always make a
complete quarter and four complete quarters, a complete year. Reduced
capture (i.e., as little as one sample per year) would also suffice for
high concentration years or 3-year periods. However, the percentile
computational variation permitted for seasonal sampling for the 24-hour
98th percentile would not be needed for the 4-hour 95th percentile
since the predominant (if not only) monitoring instrument used for this
standard would be a continuous PM2.5 sampler and EPA expects
these continuous instruments to operate throughout the entire year. For
this same reason, distinction between applicable number of samples and
actual number of samples would not be necessary.
5. Conforming Revisions
    Terminology and data handling procedures associated with
exceptional events would be revised to conform to rules which EPA plans
to propose in the near future to implement the recent amendment to CAA
section 319 (42 U.S.C. 7619) by section 6013 of the Safe, Accountable,
Flexible Efficient Transportation Equity Act: A Legacy for Users
(SAFETEA-LU) (PL 109-59). At this time, EPA is proposing to replace the
term currently used in Appendix N.1.(b)--``uncontrollable or natural
events''--with ``exceptional events,'' corresponding with the term used
in the recent amendment. (Because this proposal would make only a
semantic change to existing Appendix N, EPA believes the proposal is
consistent with section 6013 (b) (4) of SAFETEA-LU, which provides that
EPA shall continue to apply existing Appendix N of part 50 (among
others) until the effective date of rules implementing the exceptional
event provisions in amended section 319 of the CAA.)

B. Proposed Appendix P--Interpretation of the National Ambient Air
Quality Standards for PM10-2.5

    The EPA is proposing to add appendix P to 40 CFR part 50 in order
to add data handling procedures for the proposed 24-hour
PM10-2.5 standard. The proposed appendix P would detail the
computations necessary for determining when the proposed
PM10-2.5 NAAQS is met. The proposed appendix also would
address data reporting, sampling frequency considerations, and rounding
conventions. The protocols described in proposed appendix P would
mirror the general and 24-hour specific protocols proposed for the
PM2.5 NAAQS in appendix N of 40 CFR part 50. Key elements of
the proposed appendix P are summarized below in sections V.B.1 through
V.B.3 of this preamble.
1. General
    Terms utilized throughout the proposed appendix would be defined in
section 1.0.
2. PM2.5 Data Reporting Considerations
    Section 2.0 of the proposed appendix P would specify the input data
to be used in the NAAQS computations. The section would address raw
data reporting and raw data time interval aggregation (i.e., report/
calculate to one decimal place, truncate additional digits). Section
2.0 would also note the process for assimilating monitored
concentration data into a ``site'' record; data for the site record
would originate mainly from the designated ``primary'' monitor at the
site location, but would be augmented with collocated Federal reference
method or Federal equivalent method monitor data whenever valid data
are not generated by the primary monitor. This procedure would enhance
the opportunity for sites to meet data completeness requirements.
3. PM10-2.5 Computations and Data Handling Conventions
    The EPA is proposing a site-based 98th percentile concentration as
the form of the 24-hour PM2.5. The proposed appendix P would
explain data handling conventions and computations for the 24-hour
primary (and secondary) PM10-2.5 standards in section 3.1;
data

rounding conventions in section 3.2; and sampling frequency
considerations in section 3.3. The formulas used for calculating the
24-hour NAAQS metric would be specified in section 3.4.
    The proposed appendix would include a special formula (Equation 2)
for use in computing annual 98th percentile values when a site operates
on an approved seasonal sampling schedule. The proposed appendix P also
would incorporate language explicitly stating that 98th percentiles
(for both regular and seasonal sampling schedules) is to be based on
the applicable number of samples rather than actual number of samples.
Both annual 98th percentile equations (Equations 1 and 2 of proposed
appendix P) would reflect this approach. This approach parallels that
proposed in appendix N for PM2.5 described in V.A.3. above,
and is based on the same considerations.
4. Exceptional Events
    The EPA plans to use the terminology and adopt the data handling
procedures associated with exceptional events consistent with rules
which would implement the recent amendment to CAA section 319 discussed
in section V.A.5 above. The EPA expects to propose such rules in the
near future. In the present proposal, the term ``exceptional events''
is used, consistent with the term used in the recent amendment as well
as the term EPA proposes to use in the parallel provision in Appendix N
(see section V.A.5).

VI. Reference Methods for the Determination of Particulate Matter As
PM2.5 and PM10-2.5

A. Proposed Appendix O: Reference Method for the Determination of
Coarse Particulate Matter (as PM10-2.5) in the Atmosphere

1. Purpose of the New Reference Method
    The EPA is proposing a new Federal reference method (FRM) for the
measurement of coarse particles (as PM10-2.5) in ambient air
for the purpose of determining attainment of the proposed new
PM10-2.5 standards. The FRM would also serve as the standard
of comparison for determining the adequacy of alternative
``equivalent'' methods for use in lieu of the FRM. The method is
described in a proposed new appendix O to 40 CFR part 50, where it
would join other FRM (or measurement principles) specified for the
other criteria pollutants.
2. Rationale for Selection of the New Reference Method
    The proposed FRM for measuring PM10-2.5 is based on the
combination of two conventional low-volume methods, one for measuring
PM10 and the other for measuring PM2.5, and
determining the PM10-2.5 measurement by subtracting the
PM2.5 measurement from the concurrent PM10
measurement. The proposed PM2.5 measurement method is
identical to the PM2.5 FRM currently specified in appendix L
to 40 CFR part 50, and the proposed PM10 measurement method
is similar, utilizing the same sampler but without the PM2.5
particle size separator. (Both samplers use identical PM10
size-selective inlets.) Thus, this PM10-2.5 FRM is based on
the same aerodynamic particle size separation and filter-based,
gravimetric technology that is also the basis for FRMs for
PM2.5 and (in a somewhat less rigorously specified form) for
PM10.
    In selecting the FRM methodology, EPA's primary considerations were
the ability of the method to provide: (1) Credible and reliable
measurements of PM10-2.5; (2) reliable assessment of the
quality of monitoring data; and (3) a credible and practical reference
standard of comparison for candidate alternative measurement methods to
determine their qualification as equivalent methods. In concept, a
direct method for measuring PM10-2.5 would seem to be
desirable for the FRM, rather than the indirect method proposed. The
EPA tested and evaluated various types of direct measurement technology
(Vanderpool et al., 2005), including other conventional, filter-based
gravimetric methods. The results of these tests and other evaluations
indicate that none of the available methods or alternative technologies
was more suitable as a reference method for PM10-2.5 than
the method proposed.
    Perhaps the most fundamental requirement for the
PM10-2.5 FRM is the capability of the method to measure the
subject particulate matter with a high degree of fidelity and
faithfulness to the definition of PM10-2.5. In proposed
appendix O, PM10-2.5 is defined as the mass concentration of
ambient particles in the coarse-mode fraction of PM10,
specifically the (nominal) size range of 2.5 to 10 micrometers. The
lower and upper limits of this size range are formally defined by the
existing FRMs for PM2.5 (40 CFR part 50, appendix L) and for
PM10 (40 CFR part 50, appendix J). In both cases, the
particle sizes are defined in terms of aerodynamic size, not actual
physical size. Further, the particle size limits are not simple step
functions but instead are defined by the corresponding PM2.5
and PM10 measurement methodologies, which have inherent size
fractionation curves with characteristic shapes and cutoff sharpness.
The proposed PM10-2.5 FRM would utilize these same
measurement methodologies to determine the PM10-2.5
concentration as the difference between separate PM10 and
PM2.5 measurements, thereby preserving and replicating the
same particular PM10 and PM2.5 aerodynamic
particle size limit characteristics previously established by the
PM10 and PM2.5 FRMs.
    Also, the proposed PM10-2.5 FRM utilizes the same
conventional integrated-sample, filter-collection, and mass-based
gravimetric measurement technology that has been chosen for all
previous FRM for the various formal particulate matter indicators. This
well-established and reliable technology provides a high degree of
credibility in the PM10-2.5 measurements, derived from its
gravimetric basis and its extensive track record from wide utilization
over many years in many government monitoring networks. Further, it
allows for maximum compatibility and comparability among new and
existing PM10-2.5, PM10, and PM2.5
data sets and thus to much of the health effects data used as a basis
for the proposed NAAQS. No costly studies are needed to assess the
impact, effect, or degree of comparability of a new or changed
measurement technology relative to previously acquired measurement
data. Extensive wind tunnel tests have shown that the inlet, used on
both the PM2.5 and PM10 samplers, is capable of
aspirating large particles efficiently, even at high wind speeds. The
presence of PM2.5 aerosols on the PM10 sample
collection filter increases the adhesion of larger particles to the
filter to minimize losses of large particles from the PM10
filters during handling and transport. Such losses can be a problem
with filter samples collected with a virtual impactor-type sampler,
where the PM2.5 aerosols are not present on the
PM10-2.5 filter in sufficient quantities to eliminate loss
of coarse mode particles.
    An inherent advantage of a difference method is that some
(additive) biases may be eliminated or substantially reduced by the
subtraction. In the proposed PM10-2.5 FRM, the two samplers
and their operational procedures are very closely matched (except for
the particle size separator) to take maximum advantage of this feature,
which helps to compensate for the additional variability resulting from
dual measurement systems. Although a difference method could produce
negative measurements on occasion,

considerable field testing of the method indicates that negative
readings are rare, due in substantial part to the excellent precision
of the base methods (Vanderpool et al., 2005). Moreover, measured
negative PM10-2.5 concentrations, if observed, would likely
occur only at low concentrations near the detection limit of the method
and would thus be unlikely to adversely affect the accuracy of
PM10-2.5 attainment decisions based on the proposed 24-hour
NAAQS.
    The proposed method also has a number of secondary advantages. The
samplers and operational procedures of the proposed FRM are similar to
those of the PM2.5 FRM and will be familiar to most State
monitoring agencies. In fact, the nature of the method allows for the
possibility of readily and economically obtaining PM10-2.5
samplers (actually sampler pairs) by reconfiguring existing
PM2.5 samplers. PM10-2.5 sampler pairs based on
currently designated PM2.5 FRM samplers could be quickly
designated by EPA as PM10-2.5 FRM, as no additional
qualification testing would be required. Existing PM2.5 FRM
samplers can be easily reconfigured as PM10-2.5 FRM sampler
pairs by converting some of them to the special PM10
(PM10c) samplers by simply replacing the WINS impactor with
the specified straight downtube adaptor. Thus, the PM10-2.5
method could be rapidly and economically implemented into new or
existing monitoring networks to begin collection of PM10-2.5
monitoring data expeditiously, with minimal requirements for operator
retraining or pilot operational periods.
    The proposed FRM provides readily accessible aerosol samples for
subsequent chemical analyses, and the sampler's design allows use of a
wide variety of filter materials including Teflon, quartz, nylon, and
polycarbonate. Compared to PM2.5, the chemical composition
of coarse-mode aerosols has not yet been extensively evaluated. The
ability of the proposed FRM to provide speciated analyses of coarse
aerosol samples would be an important tool for the States during
development of effective implementation plans.
    In developing this new FRM for PM10-2.5, EPA staff
consulted with a number of individuals and groups in the monitoring
community, including instrument manufacturers, academics, consultants,
and experts in State and local agencies. The approach and key
specifications of the method were submitted for peer review to the
Clean Air Scientific Advisory Committee (CASAC) Ambient Air Monitoring
and Methods Subcommittee, which held public meetings to discuss methods
and related monitoring issues on July 22, 2004 and September 21 and 22,
2005. Comments on the proposed method were provided orally and in
writing by Subcommittee members and by interested public entities. In a
letter dated November 30, 2005 (Henderson, 2005c) forwarded by the
CASAC to the Administrator, the CASAC provided its peer review
consensus report stating that ``in general, the CASAC agrees that there
are several important scientific or operational strengths of the
proposed difference method PM10-2.5 to be used as the FRM,
while noting that there are several prominent weaknesses as well.
Despite these weaknesses, no other better, currently available
candidate FRM method has been identified.'' The CASAC report noted that
``A majority of the Subcommittee members expressed the opinion that the
demonstrated data quality of the PM10-2.5 difference method
and its documented value in correlations with health effects data
support its being proposed as the PM coarse FRM''. However, the CASAC
also indicated that the proposed FRM should not be intended for
extensive implementation in national monitoring networks. Instead, it
should be used primarily as a benchmark for evaluating the performance
of continuous as well as other direct-measuring, filter-based,
integrated methods and determining their acceptability for use in
routine monitoring of PM10-2.5. As explained more fully
below, this is the approach we intend to adopt for the national
monitoring network.
3. Consideration of Other Methods for the Federal Reference Method
    Other measurement technologies considered for the FRM include a
variety of alternative integrated-sample, filter-based methods as well
as various automated methods providing continuous or semi-continuous
measurements of PM10-2.5. One methodology that warranted
particular consideration is integrated, filter sampling using a virtual
impactor particle size separator (also known as a dichotomous
fractionator). This technology provides for measuring
PM10-2.5 more directly than the proposed difference method
and also provides associated PM2.5 measurements, as well as
PM10 measurements by addition. Like the proposed difference
method, dichotomous samplers have been used in health studies that
supported the basis for both the PM2.5 and proposed
PM10-2.5 NAAQS. A dichotomous sampler can utilize the same
PM10 sampler inlet, the same types of filters and filter
processing, and similar quality assurance procedures as the proposed
method. It also has a very important advantage in providing
PM10-2.5 filter samples for chemical analysis. Such
``speciation'' analysis is a critical tool used by States for
developing effective PM10-2.5 control strategies. Speciated
PM2.5 and PM10-2.5 data have supported
epidemiological studies used to develop associations between exposure
to ambient particulate matter and increased mortality and morbidity
(Dockery, et al., 1993, Schwartz, 1994). Collected speciated samples
from dichotomous samplers can also be used to conduct toxicological
studies of the adverse health effects of PM exposure as a function of
particle size (Demokritou, et al., 2003).
    However, some aspects of virtual impactor technology raise concerns
regarding the technology's current suitability for use as a
PM10-2.5 reference method. Various versions of virtual
impactors have been designed and used, but their particle size
separation characteristics have not been fully evaluated and
independently characterized as extensively as those of the proposed
method, resulting in considerable uncertainty about their performance
relative to the conventional low-volume PM2.5 and
PM10 FRMs. There is also concern about the impact and
potential need to compensate for some inherent fine particle
contamination on the PM10-2.5 filter. For example, for a
virtual impactor which employs a 10 to 1 total flow rate to coarse flow
rate ratio, 10 percent of the fine particles deposit on the coarse
filter. Following each sampling event, the presence of these fine
particles must be accounted for during subsequent calculation of the
PM10-2.5 mass concentration. Depending upon the analyte of
interest, the collected mass of the analyte, and the method detection
limit of the analytical technique for that analyte, proper compensation
for fine particle contamination will also need to be made when
conducting speciation analysis of the coarse channel filter. Allen et
al. (1999) also reported the tendency for some fraction (up to 16
percent) of coarse mode particles to penetrate to the fine channel
filter and thus positively bias calculated PM2.5 mass
concentrations as well as concentrations of specific analytes. Because
the level of coarse particle contamination depends upon the size
distribution of the sampled aerosol and the physical nature of the
coarse particles, this contamination cannot be accurately predicted and
thus cannot be

accounted for during subsequent calculations.
    Loss of particles within virtual impactors is also well documented
(Forney et al., 1982, Chen et al., 1985, Loo and Cork, 1988, Li and
Lundgren, 1997, Allen, et al., 1999, Kim and Lee, 2000) and can
substantially bias measured mass and species concentrations. As
reported by Loo and Cork (1988), losses up to 50 percent have been
reported during laboratory calibration of various virtual impactor
designs when using liquid calibration aerosols. Moreover, these losses
cannot be predicted and are very sensitive to virtual impactor geometry
and component misalignment. Unlike conventional impactors where
internal particle loss can be readily minimized, the design of virtual
impactors must be optimized to ensure that particle loss is
sufficiently low to enable accurate mass and species measurements
during field use.
    In the proposed difference method, the high concentration of fine
particles on the PM10 filter provides additional adhesive
force for retaining large particles to the filter's surface. In the
dichotomous sampler, however, the low concentration of fine particles
on the coarse channel filter results in a significantly reduced
adhesive force. If inertial forces (applied to the filter during its
post-sampling handling and transport) are greater than the adhesive
force, then coarse particles will be dislodged from the coarse channel
filter and not be subsequently quantified. Depending upon the virtual
impactor design, the nature of the collected aerosol, and the magnitude
of the applied inertial force, large particle losses up to 50 percent
have been documented (Dzubay and Barbour, 1983, Spengler and Thurston,
1983). As in the case of coarse particle intrusion into the fine
channel, the magnitude of this measurement bias is variable and cannot
be accurately predicted nor compensated for.
    The CASAC, in their peer review report (Hendersen, 2005c) supports
``* * * the possibility of specifying more than one FRM for
PM10-2.5 (as it did for PM10) , if one or more of
the current or evolving dichotomous sampler designs shows reasonable
agreement with the difference method (assuming filter-handling
procedures can be developed to minimize losses of coarse-only particles
prior to weighing).'' We agree that the filter-handling procedures need
to be investigated in addition to other issues described above.
Therefore, at this point we believe the proposed FRM, based on the
difference method, offers less uncertainty in PM10-2.5
measurements and is the more prudent choice for the reference method.
However, CASAC and EPA are both interested in utilizing dichotomous
samplers in support of other monitoring objectives, such as providing
samples for chemical speciation analysis, once a number of issues are
worked through. Therefore, the Agency wishes to solicit public comment
regarding consideration of a PM10-2.5 reference method or
equivalent method based on the use of the virtual impactors to
aerodynamically separate fine mode aerosols from coarse mode aerosols.
    Concerns have been expressed to EPA regarding the fact that the
size separation devices of both the PM2.5 and
PM10 FRMs, which are the basis of the proposed difference-
based PM10-2.5 FRM, have inherent size fractionation curves
with characteristic shapes and cutoff sharpness rather than creating a
perfectly sharp cutpoint at a specific aerodynamic particle size. For
example, a portion of all ambient particles larger than 10 micrometers
are included in the PM10-2.5 sample, while some particles
smaller than 10 micrometers are not. A larger effect on measured
PM10-2.5 will occur in environments with high concentrations
of particles above 10 micrometers than in environments with low
concentrations.
    Some commenters who have been concerned about this aspect of the
PM2.5 and PM10 FRMs have supported the adoption
of a PM10-2.5 FRM that would directly measure the coarse
fraction of particles. We invite comment on this topic, in the context
of today's proposal for a PM10-2.5 NAAQS and a FRM that
would employ both PM2.5 and PM10 size separators.
4. Consideration of Automated Methods for the Federal Reference Method
    Other measurement technologies considered for the FRM included
various types of automated analyzer methods that provide continuous or
semi-continuous measurements of PM10-2.5. Such methods are
particularly desirable for use in PM10-2.5 monitoring
networks because they potentially offer substantially lower operational
and maintenance costs, hourly averages or other short-term measurements
in addition to 24-hour averages, and nearly real-time electronic,
remote reporting of measurement data. However, recent field testing of
many of these instruments (Vanderpool et al., 2005) indicated that none
can yet achieve performance commensurate to that of the proposed
method. The technologies employed by these methods usually represent a
substantial, if not radical, departure from the well-characterized,
conventional filter-collection and gravimetric determination. This
departure raises inevitable questions of representativeness of particle
size discrimination, treatment of volatile components, variability with
differing site and climatic conditions, and the degree of comparability
to conventionally obtained measurements. Also, since EPA is proposing a
daily standard for PM10-2.5, hourly measurements are not
required to support such a standard, although they would be of value to
more closely investigate impacts of sources and exceptional events.
    Most, if not all, of these automated measurement technologies are
proprietary. While that alone is not sufficient reason to preclude
their consideration as FRM or as a ``reference measurement principle,''
it would be in the best interest of all stakeholders if multiple
manufacturers could compete for this market. Adoption of the proposed
FRM along with reasonable qualification requirements for equivalent
methods leaves a fair and level playing field for any manufacturer to
either produce the specified FRM samplers or to pursue the development
and EPA approval of innovative new methods and technologies to strive
for competitive marketing advantages.
5. Use of the Proposed Federal Reference Method
    The EPA acknowledges that the proposed FRM is quite labor-intensive
and has other disadvantages that make it less than ideal for routine
use in large monitoring networks. At the same time, as just described,
alternative, automated methods are under continuing research and
development, and some may soon demonstrate adequate performance and
comparability to the FRM for use in monitoring networks. Accordingly,
and consistent with the recommendations of the CASAC (Hendersen,
2005c), EPA is providing for the possible designation of alternative
methods as equivalent methods for PM10-2.5, as set forth in
proposed amendments to 40 CFR part 53 published elsewhere in this
Federal Register. Under these proposed equivalent method provisions,
EPA anticipates that alternative methods--particularly filter based,
virtual-impactor samplers as well as self-contained, automated
analyzers--can be designated as equivalent methods. The dichotomous
samplers could potentially lead to better speciation data, while
automated equivalent methods would ease the potential
PM10-2.5 monitoring burdens of monitoring agencies and would
potentially provide substantial

monitoring advantages such as reduced operational cost, availability of
1-hour (or other less-than-24-hour) average concentration measurements,
and near real-time telemetered monitoring data. As explained in the
preamble to the proposed Part 58 rule, if such automated methods are
designated as equivalent, they would likely be used predominantly for
much of the required PM10-2.5 network monitoring. The new
PM10-2.5 FRM would thus be used primarily as the reference
standard for designating qualified equivalent methods and for quality
assurance activities, but used only minimally for routine network
monitoring.
    Encouraging the further development of automated analyzers by
providing for their designation as equivalent methods for
PM10-2.5 could eventually lead to commercial, direct-reading
instruments that would meet multiple monitoring objectives better than
the FRM proposed today. In that event, the Agency may consider adopting
such an automated method for the FRM (or as a ``measurement principle
and calibration procedure'') under the provisions of 40 CFR 53.16,
``Supersession of reference methods.''
6. Relationship of Proposed FRM to SAFETEA-LU Requirements
    Section 6012 of the SAFETEA-LU in part requires the Administrator,
within two years, to ``develop a Federal reference method to measure
directly particles that are larger than 2.5 micrometers in diameter
without reliance on subtracting from coarse particle measurements those
particles that are equal to or smaller than 2.5 micrometers in
diameter.'' We believe that our proposed action today is consistent
with the goals of the new legislation, in that it actively promotes use
of non-difference methods through the Part 53 equivalency designation
process, and states our ultimate expectation that the monitoring
network for PM10-2.5 will utilize primarily non-difference
method monitors. Furthermore, we are actively investigating the
possibility that a dichotomous method could be an alternative FRM
within the time frame prescribed by this Act. However, we are proposing
a difference method as the FRM for PM10-2.5, for the reasons
explained above as we believe this is the only approach technically
justified at this time. Since the new statutory language does not
require that EPA promulgate a non-difference method as either the sole
or alternative FRM, we believe this proposed approach is consistent
with the express language of the provision as well as with its
objectives.
7. Basic Requirements of the Proposed Federal Reference Method Sampler
    The proposed PM10-2.5 FRM ``sampler'' is actually a
collocated pair of samplers, one for PM10 and one for
PM2.5, operated simultaneously. The PM2.5 sampler
is exactly as specified in the PM2.5 FRM (appendix L to 40
CFR part 50). The operational and procedural requirements would be the
same as those for PM2.5 FRM measurements. PM2.5
measurements obtained as part of PM10-2.5 FRM measurements
would be indistinguishable from conventional PM2.5 FRM
measurements and would be usable for any PM2.5 monitoring
purpose, provided they are sited at the appropriate spatial scale
(e.g., neighborhood scale).
    In contrast, the PM10 sampler of the PM10-2.5
sampler pair would be required to be identical in design and
construction to the PM2.5 sampler, except that the
PM2.5 particle size separator (WINS impactor) would be
removed from the sampler and replaced with a straight downtube, thereby
converting it to a PM10 sampler. This PM10
sampler would have to meet the higher standards of manufacture and
performance of appendix L to 40 CFR part 50 rather than the standards
for conventional PM10 FRM samplers (which meet the lesser
requirements of appendix J to 40 CFR part 50). Thus, PM10
measurements obtained as part of or incidental to the
PM10-2.5 FRM measurements must be distinguished from
conventional PM10 measurements and need to be identified by
a unique descriptor such as ``PM10c.'' Since
PM10c measurements would meet a higher standard than
conventional PM10 measurements, such measurements would also
be acceptable for any conventional PM10 monitoring purpose.
However, one subtle issue regarding conventional PM10
measurements and new PM10c measurements needs clarification.
Conventional PM10 measurement flow systems operate on
conditions of standard temperature and pressure (STP). Flow systems for
PM2.5 and the new PM10-2.5 FRM as proposed today
and peer reviewed by the CASAC, all operate under conditions of actual
local conditions.
    PM10-2.5 sampler pairs would be required to be
specifically designated as PM10-2.5 FRM samplers by EPA
under amendments to 40 CFR 53 proposed elsewhere in this Federal
Register. The two samplers of the PM10-2.5 FRM sampler pair
would be required to be of like manufacturer and of matched design and
fabrication so that they are essentially identical, except that one
would have a PM2.5 particle size separator while the other
would not. Either single-filter samplers or multiple-filter, sequential
samplers could constitute a PM10-2.5 sampler pair, as long
as both were of the same type and design. For a manufacturer's sampler
model that has already been designated as a PM2.5 FRM, no
further testing would be required for designation as a
PM10-2.5 FRM, although the sampler manufacturer would have
to submit a formal application under 40 CFR part 53. Users could
assemble their own PM10-2.5 sampler pair using existing
PM2.5 samplers of the same model or design by converting one
of the samplers to a PM10c sampler, provided the specific
sampler pair has been previously designated by the EPA as a
PM10-2.5 FRM under 40 CFR part 53.
    Pairings of qualified PM2.5 samplers that are dissimilar
or have some minor design or model variations (and one sampler is
converted to a PM10c sampler) could be designated by the EPA
as Class I equivalent methods under proposed amendments to 40 CFR part
53. Again, an application for an equivalent method determination for
the sampler combination would have to be submitted to the EPA under 40
CFR part 53, and not all combinations would necessarily be designated
without further testing. For example, supplemental test or operational
performance information would likely be required for designation of a
PM10-2.5 sampler pair consisting of a single-filter sampler
and a multiple-filter, sequential sampler. A pairing of dissimilar
PM2.5 samplers that has not been designated as a Class I
equivalent method for PM10-2.5 under 40 CFR part 53 could be
considered by the EPA for approved use in PM10-2.5
monitoring networks as a user modification under section 2.8 of
appendix C to 40 CFR part 58.
8. Other Important Aspects of the Proposed Federal Reference Method
Sampler
    The proposed method would require that both samplers of the
PM10-2.5 sampler pair be located in close proximity and
operated simultaneously. Operational procedures for both samplers of
the pair would be similar or identical to those specified for
PM2.5 FRM, and both samplers should be operated, serviced,
and maintained similarly. Quality assurance procedures would parallel
those for the PM2.5 FRM, although data quality assessment
procedures would apply to the calculated PM10-2.5
measurement data rather than (or in addition to) the individual
PM10 and PM2.5

measurements. The proposed sample period would be nominally 24 hours
(1 hour).
    Expected performance of the PM10-2.5 FRM--as measured by
precision, lower concentration limit, and completeness--is similar to
that of the PM2.5 FRM, but may be somewhat inferior because
of the dual measurement components. Precision, defined as a goal for
acceptable measurement uncertainty, is given as 15 percent coefficient
of variation, as assessed according to quality assurance procedures for
PM10-2.5 monitoring described in proposed revisions to
appendix A of 40 CFR part 58, published elsewhere in this Federal
Register.
    The lower concentration limit proposed for the method is 3 [mu]g/
m\3\. This value can vary with the level of quality control and
precision achieved in implementing the method. It should not be
interpreted as a specification but rather as a simple guide to the
general significance of low-level measured concentrations. However,
this proposed value may be used as a lower range limit for excluding
low-concentration data from composite performance calculations that use
percentages (where very low values in a denominator need to be avoided)
or in types of statistical calculations of monitoring data that cannot
accept zero or negative values (such as geometric distributions, where
\1/2\ of this lower concentration limit may be substituted for any
measurements less than that value). Comments are solicited on the
usefulness of this lower concentration limit, its value, or how its
value should be established and interpreted.

B. Proposed Amendments to Appendix L--Reference Method for the
Determination of Fine Particulate Matter (as PM2.5) in the
Atmosphere

    In connection with the proposal of a new Federal reference method
(FRM) for PM10-2.5, EPA is proposing minor changes to the
FRM for PM2.5 in appendix L to 40 CFR part 50. These
proposed changes are based on new test information and extensive
operational experience with the PM2.5 FRM acquired
subsequent to its promulgation in 1997. Through the increased
flexibility afforded by the proposed changes, significant improvements
in the efficiency of the PM2.5 method in monitoring network
operations are expected without altering the performance of the method.
In fact, the changes have already been implemented in the national
PM2.5 monitoring network through designated equivalent
methods or duly approved user modifications. Further, the changes would
also apply to the proposed PM10-2.5 FRM, so the benefits
would be realized for PM10-2.5 measurements as well, and
uniformity between the PM2.5 FRM and the PM2.5
portion of the PM10-2.5 FRM would be maintained.
    The most significant proposed change is the addition of an
alternative PM2.5 particle size separator. Since the
promulgation of the PM2.5 FRM in 1997, a new, very sharp cut
cyclone separator (VSCC\TM\) manufactured by BGI Incorporated, Waltham,
MA has been shown to have performance equivalent to that of the
originally specified separator (WINS impactor) (Kenny, et al., 2001;
Kenny et al., 2004; EPA, 2002b). Although the original WINS impactor
continues to show fully adequate performance in PM2.5
samplers, the new VSCC provides the same level of performance and has a
considerably longer service interval. Generally, the VSCC separator is
also physically interchangeable with the WINS where both are
manufactured for the same sampler. The proposed change would allow
either the WINS or the VSCC separator to be used in a PM2.5
FRM sampler. Currently, EPA has designated seven PM2.5
samplers configured with VSCC separators as Class II equivalent
methods.\93\ Upon promulgation of this change to appendix L, those
seven methods would be re-designated as PM2.5 FRM.
---------------------------------------------------------------------------

    \93\ List of designated reference and equivalent methods
available at http://www.epa.gov/ttn/amtic/criteria.html.

---------------------------------------------------------------------------

    Another minor change proposed for the PM2.5 FRM (and,
hence, also applicable to the proposed PM10-2.5 FRM) would
require an improved impactor oil for the PM2.5 WINS impactor
particle size separator. The new oil corrects an occasional problem of
crystallization of the original oil during sampling in cold and damp
weather and has been tested and approved as a national user
modification (EPA, 2000b). Also, the time limit specified for sample
filter retrieval time would be increased from 96 hours to 177 hours
following the end of the sample period. This change would allow the
filter to be retrieved by the morning of the eighth day after sampling
to permit recovery of up to three samples from a sequential sampler
operating on a 1-in-3 day sample schedule. Based on a study (Papp, et
al., 2002) at six sampling sites, this change has already been approved
as a national user modification (EPA, 2002a). An associated change to
ease the filter retrieval burden on monitoring agencies would modify
the current requirement that retrieved filters be weighed within 10
days after sampling, unless they are maintained at a temperature of
4[deg]C or less at all times during transport. The filter recovery
extension study (Papp, et al., 2002) showed that these limits can be
relaxed somewhat (EPA, 2000a) to allow up to 30 days for weighing the
filter if it is maintained below the average ambient temperature during
the sampling period prior to the post-collection sample equilibration.
    Finally, some of the sampler data output reporting requirements
specified in Table L-1 of appendix L to 40 CFR part 50 (e.g. flow rate
CV, sample volume, minimum and maximum temperature, minimum and maximum
pressure) have been determined to be unnecessary to report to the Air
Quality System, and the reporting requirement for these data would be
deleted. These data will be retained and available at the monitoring
agency, if needed.

VII. Statutory and Executive Order Reviews

A. Executive Order 12866: Regulatory Planning and Review

    Under Executive Order 12866 (58 FR 51735, October 4, 1993), the
Agency must determine whether a regulatory action is ``significant''
and therefore subject to Office of Management and Budget (OMB) review
and the requirements of the Executive Order. The Order defines
``significant regulatory action'' as one that is likely to result in a
rule that may:
    1. Have an annual effect on the economy of $100 million or more or
adversely affect in a material way the economy, a sector of the
economy, productivity, competition, jobs, the environment, public
health or safety, or State, local, or Tribal governments or
communities;
    2. Create a serious inconsistency or otherwise interfere with an
action taken or planned by another agency;
    3. Materially alter the budgetary impact of entitlements, grants,
user fees, or loan programs or the rights and obligations of recipients
thereof; or
    4. Raise novel legal or policy issues arising out of legal
mandates, the President's priorities, or the principles set forth in
the Executive Order.
    In view of its important policy implications and potential effect
on the economy of over $100 million, this action has been judged to be
an economically ``significant regulatory action'' within the meaning of
the Executive Order. As a result, today's action was submitted to OMB
for review. Changes made in response to OMB suggestions or
recommendations

will be documented in the public record.

B. Paperwork Reduction Act

    This action does not impose an information collection burden under
the provisions of the Paperwork Reduction Act, 44 U.S.C. 3501 et seq.
There are no information collection requirements directly associated
with the establishment of a NAAQS under section 109 of the CAA.
    Burden means the total time, effort, or financial resources
expended by persons to generate, maintain, retain, or disclose or
provide information to or for a Federal agency. This includes the time
needed to review instructions; develop, acquire, install, and utilize
technology and systems for the purposes of collecting, validating, and
verifying information, processing and maintaining information, and
disclosing and providing information; adjust the existing ways to
comply with any previously applicable instructions and requirements;
train personnel to be able to respond to a collection of information;
search data sources; complete and review the collection of information;
and transmit or otherwise disclose the information.
    An agency may not conduct or sponsor, and a person is not required
to respond to a collection of information unless it displays a
currently valid OMB control number. The OMB control numbers for EPA's
regulations in 40 CFR are listed in 40 CFR part 9.

C. Regulatory Flexibility Act

    The Regulatory Flexibility Act (RFA) generally requires an agency
to prepare a regulatory flexibility analysis of any rule subject to
notice and comment rulemaking requirements under the Administrative
Procedure Act or any other statute unless the agency certifies that the
rule will not have a significant economic impact on a substantial
number of small entities. Small entities include small businesses,
small organizations, and small governmental jurisdictions.
    For purposes of assessing the impacts of today's rule on small
entities, small entity is defined as: (1) A small business that is a
small industrial entity as defined by the Small Business
Administration's (SBA) regulations at 13 CFR 121.201; (2) a small
governmental jurisdiction that is a government of a city, county, town,
school district or special district with a population of less than
50,000; and (3) a small organization that is any not-for-profit
enterprise which is independently owned and operated and is not
dominant in its field.
    After considering the economic impacts of today's proposed rule on
small entities, I certify that this action will not have a significant
economic impact on a substantial number of small entities. This
proposed rule will not impose any requirements on small entities.
Rather, this rule establishes national standards for allowable
concentrations of particulate matter in ambient air as required by
section 109 of the CAA. See also American Trucking Associations v. EPA.
175 F. 3d at 1044-45 (NAAQS do not have significant impacts upon small
entities because NAAQS themselves impose no regulations upon small
entities). We continue to be interested in the potential impacts of the
proposed rule on small entities and welcome comments on issues related
to such impacts.

D. Unfunded Mandates Reform Act

    Title II of the Unfunded Mandates Reform Act of 1995 (UMRA), Public
Law 104-4, establishes requirements for Federal agencies to assess the
effects of their regulatory actions on State, local, and Tribal
governments and the private sector. Under section 202 of the UMRA, EPA
generally must prepare a written statement, including a cost-benefit
analysis, for proposed and final rules with ``Federal mandates'' that
may result in expenditures to State, local, and Tribal governments, in
the aggregate, or to the private sector, of $100 million or more in any
1 year. Before promulgating an EPA rule for which a written statement
is needed, section 205 of the UMRA generally requires EPA to identify
and consider a reasonable number of regulatory alternatives and adopt
the least costly, most cost-effective or least burdensome alternative
that achieves the objectives of the rule. The provisions of section 205
do not apply when they are inconsistent with applicable law. Moreover,
section 205 allows EPA to adopt an alternative other than the least
costly, most cost-effective or least burdensome alternative if the
Administrator publishes with the final rule an explanation why that
alternative was not adopted. Before EPA establishes any regulatory
requirements that may significantly or uniquely affect small
governments, including Tribal governments, it must have developed under
section 203 of the UMRA a small government agency plan. The plan must
provide for notifying potentially affected small governments, enabling
officials of affected small governments to have meaningful and timely
input in the development of EPA regulatory proposals with significant
Federal intergovernmental mandates, and informing, educating, and
advising small governments on compliance with the regulatory
requirements.
    Today's rule contains no Federal mandates (under the regulatory
provisions of Title II of the UMRA) for State, local, or Tribal
governments or the private sector. The rule imposes no new expenditure
or enforceable duty on any State, local or Tribal governments or the
private sector, and EPA has determined that this rule contains no
regulatory requirements that might significantly or uniquely affect
small governments. Furthermore, as indicated previously, in setting a
NAAQS EPA cannot consider the economic or technological feasibility of
attaining ambient air quality standards, although such factors may be
considered to a degree in the development of State plans to implement
the standards. See also American Trucking Associations v. EPA, 175 F.
3d at 1043 (noting that because EPA is precluded from considering costs
of implementation in establishing NAAQS, preparation of a Regulatory
Impact Analysis pursuant to the Unfunded Mandates Reform Act would not
furnish any information which the court could consider in reviewing the
NAAQS). Accordingly, EPA has determined that the provisions of sections
202, 203, and 205 of the UMRA do not apply to this proposed decision.
The EPA acknowledges, however, that any corresponding revisions to
associated SIP requirements and air quality surveillance requirements,
40 CFR part 51 and 40 CFR part 58, respectively, might result in such
effects. Accordingly, EPA has addressed unfunded mandates in the notice
that announces the proposed revisions to 40 CFR part 58, and will, as
appropriate, address unfunded mandates when it proposes any revisions
to 40 CFR part 51.

E. Executive Order 13132: Federalism

    Executive Order 13132, entitled ``Federalism'' (64 FR 43255, August
10, 1999), requires EPA to develop an accountable process to ensure
``meaningful and timely input by State and local officials in the
development of regulatory policies that have federalism implications.''
``Policies that have federalism implications'' is defined in the
Executive Order to include regulations that have ``substantial direct
effects on the States, on the relationship between the national
government and the States, or on the distribution of power and
responsibilities among the various levels of government.''
    This proposed rule does not have federalism implications. It will
not have

substantial direct effects on the States, on the relationship between
the national government and the States, or on the distribution of power
and responsibilities among the various levels of government, as
specified in Executive Order 13132. The rule does not alter the
relationship between the Federal government and the States regarding
the establishment and implementation of air quality improvement
programs as codified in the CAA. Under section 109 of the CAA, EPA is
mandated to establish NAAQS; however, CAA section 116 preserves the
rights of States to establish more stringent requirements if deemed
necessary by a State. Furthermore, this rule does not impact CAA
section 107 which establishes that the States have primary
responsibility for implementation of the NAAQS. Finally, as noted in
section E (above) on UMRA, this rule does not impose significant costs
on State, local, or Tribal governments or the private sector. Thus,
Executive Order 13132 does not apply to this rule.
    However, as also noted in section E (above) on UMRA, EPA recognizes
that States will have a substantial interest in this rule and any
corresponding revisions to associated SIP requirements and air quality
surveillance requirements, 40 CFR part 51 and 40 CFR part 58,
respectively. Therefore, in the spirit of Executive Order 13132, and
consistent with EPA policy to promote communications between EPA and
State and local governments, EPA specifically solicits comment on this
proposed rule from State and local officials.

F. Executive Order 13175: Consultation and Coordination With Indian
Tribal Governments

    Executive Order 13175, entitled ``Consultation and Coordination
with Indian Tribal Governments'' (65 FR 67249, November 9, 2000),
requires EPA to develop an accountable process to ensure ``meaningful
and timely input by tribal officials in the development of regulatory
policies that have tribal implications.'' This rule concerns the
establishment of PM NAAQS. The Tribal Authority Rule gives Tribes the
opportunity to develop and implement CAA programs such as the PM NAAQS,
but it leaves to the discretion of the Tribe whether to develop these
programs and which programs, or appropriate elements of a program, they
will adopt.
    This proposed rule does not have Tribal implications, as specified
in Executive Order 13175. It does not have a substantial direct effect
on one or more Indian Tribes, since Tribes are not obligated to adopt
or implement any NAAQS. Thus, Executive Order 13175 does not apply to
this rule.
    Although Executive Order 13175 does not apply to this rule, EPA
contacted tribal environmental professionals during the development of
this rule. The EPA staff participated in the regularly scheduled Tribal
Air call sponsored by the National Tribal Air Association during the
summer and fall of 2005 as this proposal was under development. Also,
EPA is sending notice and an opportunity for comment to Tribal Leaders
within the lower 48 states. Specifically, EPA solicits additional
comment on this proposed rule from Tribal officials.

G. Executive Order 13045: Protection of Children From Environmental
Health Risks and Safety Risks

    Executive Order 13045, ``Protection of Children from Environmental
Health Risks and Safety Risks'' (62 FR 19885, April 23, 1997) applies
to any rule that: (1) is determined to be ``economically significant''
as defined under Executive Order 12866, and (2) concerns an
environmental health or safety risk that EPA has reason to believe may
have a disproportionate effect on children. If the regulatory action
meets both criteria, the Agency must evaluate the environmental health
or safety effects of the planned rule on children, and explain why the
planned regulation is preferable to other potentially effective and
reasonably feasible alternatives considered by the Agency.
    This proposed rule is subject to Executive Order 13045 because it
is an economically significant regulatory action as defined by
Executive Order 12866, and we believe that the environmental health
risk addressed by this action may have a disproportionate effect on
children. The proposed NAAQS will establish uniform, national standards
for PM pollution; these standards are designed to protect public health
with an adequate margin of safety, as required by CAA section 109.
However, the protection offered by these standards may be especially
important for children because children, along with other sensitive
population subgroups such as the elderly and people with existing heart
or lung disease, are potentially susceptible to health effects
resulting from PM exposure. Because children are considered a
potentially susceptible population, we have carefully evaluated the
environmental health effects of exposure to PM pollution among
children. These effects and the size of the population affected are
summarized in section 9.2.4 of the Criteria Document and section 3.5 of
the Staff Paper, and the results of our evaluation of the effect of PM
pollution on children are discussed in sections II.A, B, and C and
III.A, B, and C of this preamble.

H. Executive Order 13211: Actions That Significantly Affect Energy
Supply, Distribution or Use

    This proposed rule is not a ``significant energy action'' as
defined in Executive Order 13211, ``Actions Concerning Regulations That
Significantly Affect Energy Supply, Distribution, or Use'' (66 FR 28355
(May 22, 2001)) because it is not likely to have a significant adverse
effect on the supply, distribution, or use of energy. The purpose of
this rule is to establish NAAQS for PM. The rule does not prescribe
specific pollution control strategies by which these ambient standards
will be met. Such strategies will be developed by States on a case-by-
case basis, and EPA cannot predict whether the control options selected
by States will include regulations on energy suppliers, distributors,
or users. Thus, EPA concludes that this rule is not likely to have any
adverse energy effects and does not constitute a significant energy
action as defined in Executive Order 13211.

I. National Technology Transfer Advancement Act

    Section 12(d) of the National Technology Transfer Advancement Act
of 1995 (NTTAA), Public Law No. 104-113, Sec.  12(d) (15 U.S.C. 272
note) directs EPA to use voluntary consensus standards in its
regulatory activities unless to do so would be inconsistent with
applicable law or otherwise impractical. Voluntary consensus standards
are technical standards (e.g., materials specifications, test methods,
sampling procedures, and business practices) that are developed or
adopted by voluntary consensus standards bodies. The NTTAA directs EPA
to provide Congress, through OMB, explanations when the Agency decides
not to use available and applicable voluntary consensus standards.
    The proposed rule establishes requirements for environmental
monitoring and measurement. Specifically, it would establish the FRM
for PM10-2.5 measurement (and slightly amend the FRM for
PM2.5). The FRM is the benchmark against which all ambient
monitoring methods are measured. While the FRM is not a voluntary
consensus standard, the proposed revisions to the FEM in 40 CFR part 53
do allow for the utilization of voluntary consensus standards if they
meet the specified performance criteria.

    To the extent feasible, EPA employs a Performance-Based Measurement
System (PBMS), which does not require the use of specific, prescribed
analytic methods. The PBMS is defined as a set of processes wherein the
data quality needs, mandates or limitations of a program or project are
specified, and serve as criteria for selecting appropriate methods to
meet those needs in a cost-effective manner. It is intended to be more
flexible and cost effective for the regulated community; it is also
intended to encourage innovation in analytical technology and improved
data quality. Though the FRM defines the particular specifications for
ambient monitors, there is some variability with regard to how monitors
measure PM, depending on the type and size of PM and environmental
conditions. Therefore, it is not practically possible to fully define
the FRM in performance terms. Nevertheless, our approach in the past
has resulted in multiple brands of monitors qualifying as FRM for PM,
and we expect this to continue. Also, the FRM described in this
proposal and the equivalency criteria contained in the proposed
revisions to 40 CFR part 53 do constitute performance based criteria
for the instruments that will actually be deployed for monitoring
PM10-2.5. Therefore, for most of the measurements that will
be made and most of the measurement systems that make them, EPA is not
precluding the use of any method, whether it constitutes a voluntary
consensus standard or not, as long as it meets the specified
performance criteria.
    The EPA welcomes comments on this aspect of the proposed rulemaking
and, specifically, invites the public to identify potentially
applicable voluntary consensus standards and to explain why such
standards should be used in this regulation.

J. Executive Order 12898: Federal Actions To Address Environmental
Justice in Minority Populations and Low-Income Populations

    Executive Order 12898, ``Federal Actions to Address Environmental
Justice in Minority Populations and Low-Income Populations,'' requires
Federal agencies to consider the impact of programs, policies, and
activities on minority populations and low-income populations.
According to EPA guidance, agencies are to assess whether minority or
low income populations face risks or a rate of exposure to hazards that
are significant and that ``appreciably exceed or is likely to
appreciably exceed the risk or rate to the general population or to the
appropriate comparison group.'' (EPA, 1998)
    In accordance with Executive Order 12898, the Agency has considered
whether these proposals, if promulgated, may have disproportionate
negative impacts on minority or low income populations. The Agency
expects these proposals would lead to the establishment of uniform
NAAQS for PM.

References

Abbey, D. E.; Nishino, N.; McDonnell, W. F.; Burchette, R. J.;
Knutsen, S. F.; Beeson, L.; Yang, J. X. (1999) Long-term inhalable
particles and other air pollutants related to mortality in
nonsmokers. Am. J. Respir. Crit. Care Med. 159:373-382.
Abt Associates Inc. (1996). ``A Particulate Matter Risk Assessment
for Philadelphia and Los Angeles.'' Bethesda, MD. Prepared for the
Office of Air Quality Planning and Standards, U.S. Environmental
Protection Agency, Contract No. 68-W4-0029. July 3 (revised
November). Available: http://www.epa.gov/ttn/naaqs/standards/pm/s_pm_pr_td.html
.

Abt Associates Inc. (1997a). Abt Associates Memorandum to U.S. EPA.
Subject: Revision of Mortality Incidence Estimates Based on Pope et
al. (1995) in the Abt Particulate Matter Risk Assessment Report.
June 5, 1997.
Abt Associates Inc. (1997b). Abt Associates Memorandum to U.S. EPA.
Subject: Revision of Mortality Incidence Estimates Based on Pope et
al. (1995) in the December 1996 Supplement to the Abt Particulate
Matter Risk Assessment Report. June 6, 1997.
Abt Associates, Inc. (2001). Assessing Public Opinions on Visibility
Impairment Due to Air Pollution: Summary Report. Prepared for EPA
Office of Air Quality Planning and Standards; funded under EPA
Contract No. 68-D-98-001. Bethesda, Maryland. January 2001.
Abt Associates Inc. (2002). Proposed Methodology for Particulate
Matter Risk Analyses for Selected Urban Areas: Draft Report.
Bethesda, MD. Prepared for the Office of Air Quality Planning and
Standards, U.S. Environmental Protection Agency, Contract No. 68-D-
03-002. Available: http://www.epa.gov/ttn/naaqs/standards/pm/s_pm_cr_td.html
.

Abt Associates Inc. (2005). Particulate Matter Health Risk
Assessment for Selected Urban Areas. Draft Report. Bethesda, MD.
Prepared for the Office of Air Quality Planning and Standards, U.S.
Environmental Protection Agency, Contract No. 68-D-03-002.
Available: http://www.epa.gov/ttn/naaqs/standards/pm/s_pm_cr_td.html
.

Allen, G., Oh, J., Koutrakis, P., Sioutus, C. (1999). Techniques for
High-Quality Ambient Coarse Particle Mass Measurements. J. Air Waste
Manage. Assoc. 49:133-141.
Arizona Department of Environmental Quality (2003). Visibility Index
Oversight Committee Final Report: Recommendation for a Phoenix Area
Visibility Index. March 5, 2003. http://www.phoenixvis.net/PDF/vis_031403final.pdf
.

Becker, S.; Soukup, J. M.; Sioutas, C.; Cassee, F. R. (2003).
Response of human alveolar macrophages to ultrafine, fine and coarse
urban air pollution particles. Exp. Lung Res. 29: 29-44.
Burnett, R. T.; Cakmak, S.; Brook, J. R.; Krewski, D. (1997). The
role of particulate size and chemistry in the association between
summertime ambient air pollution and hospitalization for
cardiorespiratory diseases. Environ. Health Perspect. 105:614-620.
Burnett, R. T.; Brook, J.; Dann, T.; Delocla, C.; Philips, O.;
Cakmak, S.; Vincent, R.; Goldberg, M. S.; Krewski, D. (2000).
Association between particulate- and gas-phase components of urban
air pollution and daily mortality in eight Canadian cities.
Inhalation Toxicol. 12 (suppl. 4): 15-39.
Burnett, R. T.; Goldberg, M. S. (2003). Size-fractionated
particulate mass and daily mortality in eight Canadian cities. In:
Revised analyses of time-series studies of air pollution and health.
Special report. Boston, MA: Health Effects Institute; pp. 85-90.
Available: http://www.healtheffects.org/news.htm. May 16, 2003.

California Code of Regulations. Title 17, Section 70200, Table of
Standards.
Centers for Disease Control and Prevention (2004). The health
consequences of smoking: a report of the Surgeon General. Atlanta,
GA: U.S. Department of Health and Human Services, National Center
for Chronic Disease Prevention and Health Promotion, Office on
Smoking and Health. Available: http://www.cdc.gov/tobacco/sgr/sgr_2004/chapters.htm.
 August 18, 2004.

Chen, B.T., Yeh, H.C., Cheng, Y.S. (1985). A Novel Virtual Impactor:
Calibration and Use. J. Aerosol Sci. 16:343-354.
Chen, L.; Yang, W.; Jennison, B. L.; Omaye, S. T. (2000). Air
particulate pollution and hospital admissions for chronic
obstructive pulmonary disease in Reno, Nevada. Inhalation Toxicol.
12:281-298.
Chestnut , L. G.; Rowe, R. D. (1991). Economic valuation of changes
in visibility: A state of the science assessment. Sector B5 Report
27. In Acidic Depositions: State of Science and Technology Volume IV
Control Technologies, Future Emissions and Effects Valuation. P.M.
Irving (ed.). The U.S. National Acid Precipitation Assessment
Program. GPO, Washington, DC.
Chestnut, L. G.; Dennis, R. L. (1997). Economic benefits of
improvements in visibility: acid rain provisions of the 1990 clean
air act amendments. J. Air Waste Manage. Assoc. 47:395-402.
Chock, D. P.; Winkler, S.; Chen, C. (2000). A study of the
association between daily mortality and ambient air pollutant
concentrations in Pittsburgh, Pennsylvania. J. Air Waste Manage.
Assoc. 50:1481-1500.
Choudhury, A. H.; Gordian, M. E.; Morris, S. S. (1997) Associations
between

respiratory illness and PM10 air pollution. Arch.
Environ. Health 52:113-117.
Cohen, S.; Evans, G.W.; Stokols, D.; Krantz, D.S. (1986). Behavior,
Health, and Environmental Stress. Plenum Press. New York, NY.
Deck, L. B.; Post, E.S.; Smith, E.; Wiener, M.; Cunningham, K.;
Richmond, H. (2001). Estimates of the health risk reductions
associated with attainment of alternative particulate matter
standards in two U.S. cities. Risk Anal. 21(5):821-835.
Delfino, R. J.; Murphy-Moulton, A. M.; Burnett, R. T.; Brook, J. R.;
Becklake, M. R. (1997). Effects of air pollution on emergency room
visits for respiratory illnesses in Montreal, Quebec. Am. J. Respir.
Crit. Care Med. 155:568-576.
Delfino, R. J.; Zeiger, R. S.; Seltzer, J. M.; Street, D. G. (1998).
Symptoms in pediatric asthmatic and air pollution: differences in
effects by symptom severity, anti-inflammatory medication use and
particulate averaging time. Environ. Health Perspect. 106:751-761.
Demokritou, P., Tarun, G., Ferguson, S., Koutrakis, P. (2003).
Development of a High-Volume Concentrated Ambient Particles System
(CAPS) for Human and Animal Inhalation Toxicological Studies.
Inhalation Toxicol. 15:111-129.
Diociaiuti, M.; Balduzzi, M.; De Berardis, B.; Cattani, G.;
Stacchini, G.; Ziemacki, G.; Marconi, A.; Paoletti, L. (2001) The
two PM2.5 (fine) and PM2.5-10 (coarse)
fractions: evidence of different biological activity. Environ. Res.
A 86:254-262.
Dockery, D. W.; Pope, C. A., III; Xu, X.; Spengler, J. D.; Ware, J.
H.; Fay, M. E.; Ferris, B. G., Jr.; Speizer, F. E. (1993). An
association between air pollution and mortality in six U.S. cities.
N. Engl. J. Med. 329:1753-1759.
Dockery, D. W.; Cunningham, J.; Damokosh, A. I.; Neas, L. M.;
Spengler, J. D.; Koutrakis, P.; Ware, J. H.; Raizenne, M.; Speizer,
F. E. (1996). Health effects of acid aerosols on North American
children: respiratory symptoms. Environ. Health Perspect. 104:500-
505.
Dominici, F.; McDermott, A.; Daniels, M.; Zeger, S. L.; Samet, J. M.
(2003). Mortality among residents of 90 cities. In: Revised analyses
of time-series studies of air pollution and health. Special report.
Boston, MA: Health Effects Institute; pp. 9-24. Available: http://www.healtheffects.org/Pubs/TimeSeries.pdf.
 May 12, 2004.

Driscoll, C. T.; Lawrence, G. B.; Bulger, A. J.; Butler, T. J.;
Cronan, C. S.; Eagar, C.; Lambert, K. F.; Likens, G. E.; Stoddard,
J. L.; Weathers, K. C. (2001). Acidic deposition in the northeastern
United States: sources and inputs, ecosystem effects, and management
strategies. BioScience 51:180-198.
Dzubay, T.G., Barbour, R.K. (1983). A Method to Improve the Adhesion
of Aerosol Particles on Teflon Filters. JAPCA, 33: 692-695.
Ely, D.W.; Leary, J.T.; Stewart, T.R.; Ross, D.M. (1991). The
Establishment of the Denver Visibility Standard. For presentation at
the 84th Annual Meeting & Exhibition of the Air and Waste Management
Association, June 16-21, 1991.
Environmental Protection Agency (1996a). Air Quality Criteria for
Particulate Matter. Research Triangle Park, NC: National Center for
Environmental Assessment-RTP Office; report no. EPA/600/P-95/001aF-
cF. 3v
Environmental Protection Agency (1996b). Review of the National
Ambient Air Quality Standards for Particulate Matter: Policy
Assessment of Scientific and Technical Information, OAQPS Staff
Paper. Research Triangle Park, NC 27711: Office of Air Quality
Planning and Standards; report no. EPA-452\R-96-013.
Environmental Protection Agency (1999). Regional Haze Regulations.
40 CFR Part 51.300-309. 64 Federal Register 35713.
Environmental Protection Agency (2000a). Memorandum from David
Mobley, EPA-OAQPS to EPA Regional Office Air Directors, dated
January 19, regarding Additional Guidance on PM2.5
Cassette Handling and Transportation. Available: http://www.epa.gov/ttn/amtic/files/ambient/pm25/pm25caset.pdf
.

Environmental Protection Agency (2000b). Memorandum from Elizabeth
Hunike, EPA-NERL-Process Modeling Research Branch to Lee Ann Byrd,
EPA-OAQPS-MQAG, dated November 30, regarding Alternative WINS oil.
Available: http://www.epa.gov/ttn/amtic/files/cfr/recent/letter.pdf.

Environmental Protection Agency (2001). Particulate Matter NAAQS
Risk Analysis Scoping Plan, Draft. Research Triangle Park, NC:
Office of Air Quality Planning and Standards. Available: http://www.epa.gov/ttn/naaqs/standards/pm/s_pm_cr_td.html
.

Environmental Protection Agency (2002a). Memorandum from David
Mobley, EPA-OAQPS to EPA Regional Office Air Directors, dated
February 22, regarding ``Extension of Filter Retrieval Time for
PM2.5 Samples.'' Available: http://www.epa.gov/ttn/amtic/files/ambinet/pm25/filtere.pdf
.

Environmental Protection Agency (2002b). 67 Federal Register 15566.
April 2, 2002.
Environmental Protection Agency (2003). Response Of Surface Water
Chemistry to the Clean Air Act Amendments of 1990. National Health
and Environmental Effects Research Laboratory, Office of Research
and Development, U.S. Environmental Protection Agency. Research
Triangle Park, NC. EPA 620/R-03/001.
Environmental Protection Agency (2004). Air Quality Criteria for
Particulate Matter. Research Triangle Park, NC: National Center for
Environmental Assessment-RTP Office; report no. EPA/600/P-99/002aD.
Environmental Protection Agency. (2005a) Review of the National
Ambient Air Quality Standards for Particulate Matter: Policy
Assessment of Scientific and Technical Information, OAQPS Staff
Paper. Research Triangle Park, NC 27711: Office of Air Quality
Planning and Standards; report no. EPA-452/R-05-005. June 2005.
Environmental Protection Agency. (2005b) Review of the National
Ambient Air Quality Standards for Particulate Matter: Policy
Assessment of Scientific and Technical Information, OAQPS Staff
Paper. Research Triangle Park, NC 27711: Office of Air Quality
Planning and Standards; report no. EPA EPA-452/R-05-005a. December
2005.
Fairley, D. (2003). Mortality and air pollution for Santa Clara
County, California, 1989-1996. In: Revised analyses of time-series
studies of air pollution and health. Special report. Boston, MA:
Health Effects Institute; pp. 97-106. Available: http://www.healtheffects.org/Pubs/TimeSeries.pdf.
 October 18, 2004.

Forney, L.J., Ravenhall, D.G., Lee, S.S. (1982). Experimental and
Theoretical Study of a Two-Dimensional Virtual Impactor. Environ.
Sci. Technol. 16: 492-497.
Galloway, J. N.; Cowling, E. B. (2002). Reactive nitrogen and the
world: 200 years of change. Ambio 31: 64-71.
Gauderman, W. J.; McConnell, R.; Gilliland, F.; London, S.; Thomas,
D.; Avol, E.; Vora, H.; Berhane, K.; Rappaport, E. B.; Lurmann, F.;
Margolis, H. G.; Peters, J. (2000). Association between air
pollution and lung function growth in southern California children.
Am. J. Respir. Crit. Care Med. 162: 1383-1390.
Gauderman, W. J.; Gilliland, G. F.; Vora, H.; Avol, E.; Stram, D.;
McConnell, R.; Thomas, D.; Lurmann, F.; Margolis, H. G.; Rappaport,
E. B.; Berhane, K.; Peters, J. M. (2002). Association between air
pollution and lung function growth in southern California children:
results from a second cohort. Am. J. Respir. Crit. Care Med. 166:
76-84.
Gold, D. R.; Litonjua, A.; Schwartz, J.; Lovett, E.; Larson, A.;
Nearing, L.; Allen, G.; Verrier, M.; Cherry, R.; Verrier, R. (2000)
Ambient pollution and heart rate variability. Circulation 101:1267-
1273.
Goldberg, M. S.; Burnett, R. T. (2003) Revised analysis of the
Montreal time-series study. In: Revised analyses of time-series
studies of air pollution and health. Special report. Boston, MA:
Health Effects Institute; pp. 113-132. Available: http://www.healtheffects.org/Pubs/TimeSeries.pdf
 [18 October, 2004].

Gordian, M. E.; [Ouml]zkaynak, H.; Xue, J.; Morris, S. S.; Spengler,
J. D. (1996) Particulate air pollution and respiratory disease in
Anchorage, Alaska. Environ. Health Perspect. 104:290-297.
Grand Canyon Visibility Transport Commission (1996). Report of the
Grand Canyon Visibility Transport Commission to the United States
Environmental Protection Agency.
Gunn, J.M. and Mills, K.H. (1998). The potential for restoration of
acid-damaged lake trout lakes. Restoration Ecology. 6:390-397.
Health Effects Institute (2000). Commentary on the National
Morbidity, Mortality and Air Pollution Study. Part II: morbidity,
mortality and air pollution in the United States. Boston, MA: Health
Effects Institute; research report no. 94, pp. 73-

81. Available: http://www.healtheffects.org/Pubs/Samet2.pdf. June,

2000.
Health Effects Institute (2003). Commentary on revised analyses of
selected studies. In: Revised analyses of time-series studies of air
pollution and health. Special report. Boston, MA: Health Effects
Institute; pp. 255-290. Available: http://www.healtheffects.org/Pubs/TimeSeries.pdf.
 October 18, 2004.

Hedin, L. O.; Granat, L.; Likens, G. E.; Buishand, T. A.; Galloway,
J. N.; Butler, T. J.; Rodhe, H. (1994). Steep declines in
atmospheric base cations in regions of Europe and North America.
Nature (London) 367:351-354.
Hefflin, B. J.; Jalaludin, B.; McClure, E.; Cobb, N.; Johnson, C.
A.; Jecha, L.; Etzel, R. A. (1994). Surveillance for dust storms and
respiratory diseases in Washington State, 1991. Arch. Environ.
Health 49:170-174.
Henderson, R. (2005a). EPA's Review of the National Ambient Air
Quality Standards for Particulate Matter (Second Draft PM Staff
Paper, January 2005): A review by the Particulate Matter Review
Panel of the EPA Clean Air Scientific Advisory Committee. June 6,
2005. Available: http://www.epa.gov/sab/pdf/casac-05 007.pdf.

Henderson, R. (2005b). Clean Air Scientific Advisory Committee
(CASAC) Review of the EPA Staff Recommendations Concerning a
Potential Thoracic Coarse PM Standard in the Review of the National
Ambient Air Quality Standards for Particulate Matter: Policy
Assessment of Scientific and Technical Information (Final PM OAQPS
Staff Paper, EPA-452/R-05-005). September 15, 2005. Available:
http://www.epa.gov/sab/panels/casacpmpanel.html.

Henderson, R. (2005c). Letter to the EPA Administrator from the
Clean Air Scientific Advisory Committee, dated November 30, 2005,
regarding peer review of the proposed Federal reference method for
PM10-2.5. Available: http://www.epa.gov/sab/pdf/casac_06001.pdf
.

Hopke, P. (2002). Letter from Dr. Phil Hopke, Chair, Clean Air
Scientific Advisory Committee (CASAC) to Honorable Christine Todd
Whitman, Administrator, U.S. EPA. Final advisory review report by
the CASAC Particulate Matter Review Panel on the proposed
particulate matter risk assessment. May 23, 2002. Available: http://www.epa.gov/sab/pdf/casacadv02002.pdf
.

Hornberg, C.; Maciuleviciute, L.; Seemayer, N. H.; Kainka, E.
(1998). Induction of sister chromatid exchanges (SCE) in human
tracheal epithelial cells by the fractions PM-10 and
PM-2.5 of airborne particulates. Toxicol. Lett. 96/97:
215-220.
Ito, K. (2003). Associations of particulate matter components with
daily mortality and morbidity in Detroit, Michigan. In: Revised
analyses of time-series studies of air pollution and health. Special
report. Boston, MA: Health Effects Institute; pp. 143-156.
Available: http://www.healtheffects.org/Pubs/TimeSeries.pdf. May 12,

2004.
Kenny L.C.; Thorp, A. (2001). Evaluation of VSCC Cyclones. Health &
Safety Laboratory Report  IR/L/EXM/01/01 (2001). Available:
http://www.bgiusa.com/aam/vsccref6.pdf.

Kenny, L; Merrifield, T.; Gussman, R.; Thorp, A. (2004). The
Development and Designation of a New USEPA-Approved Fine Particle
Inlet: A Study of the USEPA Designation Process. Aerosol Science &
Technology, 38 (supplement 2): 15-22.
Kim, M.C., Lee, K.W. (2000). Design Modification of Virtual Impactor
for Enhancing Particle Concentration Performance. Aerosol Sci.
Technol. 32: 233-242.
Kleinman, M.T.; Bhalla, D.K.; Mautz, W.J.; Phalen, R.F. (1995)
Cellular and immunologic injury with PM-10 inhalation. Inhalation
Toxicol. 7:589-602.
Klemm, R. J.; Mason, R. (2003). Replication of reanalysis of Harvard
Six-City mortality study. In: Revised analyses of time-series
studies of air pollution and health. Special report. Boston, MA:
Health Effects Institute; pp. 165-172. Available: http://www.healtheffects.org/Pubs/TimeSeries.pdf.
 May 12, 2004.

Krewski, D.; Burnett, R. T.; Goldberg, M. S.; Hoover, K.;
Siemiatycki, J.; Jerrett, M.; Abrahamowicz, M.; White, W. H. (2000).
Reanalysis of the Harvard Six Cities Study and the American Cancer
Society Study of particulate air pollution and mortality. A special
report of the Institute's particle epidemiology reanalysis project.
Cambridge, MA: Health Effects Institute.
Li, S., Lundgren, D.A. (1997). Effect of Clean Air Core Geometry on
Fine Particle Contamination and Calibration of a Virtual Impactor.
Aerosol Sci. Technol. 27: 625-635.
Lipfert, F. W.; Morris, S. C.; Wyzga, R. E. (2000a). Daily mortality
in the Philadelphia metropolitan area and size-classified
particulate matter. J. Air Waste Manage. Assoc. 50:1501-1513.
Lipfert, J. W.; Perry, H. M., Jr.; Miller, J. P.; Baty, J. D.;
Wyzga, R. E.; Carmody, S. E. (2000b). The Washington University-EPRI
veteran's cohort mortality study: preliminary results. Inhalation
Toxicol. 12(Suppl. 4):41-73.
Lippmann, M.; Ito, K.; Nadas, A.; Burnett, R. T. (2000). Association
of particulate matter components with daily mortality and morbidity
in urban populations. Cambridge, MA: Health Effects Institute;
research report 95.
Lokke, H.; Bak, J.; Falkengren-Grerup, U.; Finlay, R. D.;
Ilvesniemi, H.; Nygaard, P. H.; Starr, M. (1996). Critical loads of
acidic deposition for forest soils: is the current approach
adequate. Ambio 25: 510-516.
Loo, B.W.; Cork, C.P. (1988). Development of High Efficiency Virtual
Impactors. Aerosol Sci. Technol. 9: 167-176.
Mar, T. F.; Norris, G. A.; Larson, T. V.; Wilson, W. E.; Koenig, J.
Q. (2003). Air pollution and cardiovascular mortality in Phoenix,
1995-1997. In: Revised analyses of time-series studies of air
pollution and health. Special report. Boston, MA: Health Effects
Institute; pp. 177-182. Available: http://www.healtheffects.org/Pubs/TimeSeries.pdf.
 October 18, 2004.

Mauderly, J.; Neas, L.; Schlesinger, R. (1998) PM monitoring needs
related to health effects. In: Atmospheric observations: helping
build the scientific basis for decisions related to airborne
particulate matter; Report of the PM measurements research workshop,
July 22-23, 1998. Available from ``PM Measurements Report'', Health
Effects Institute, 955 Massachusetts Ave., Cambridge, MA 02139.
McConnell, R.; Berhane, K.; Gilliland, F.; London, S. J.; Vora, H.;
Avol, E.; Gauderman, W. J.; Margolis, H. G.; Lurmann, F.; Thomas, D.
C.; Peters, J. M. (1999). Air pollution and bronchitic symptoms in
southern California children with asthma. Environ. Health Perspect.
107: 757-760.
McDonnell, W. F.; Nishino-Ishikawa, N.; Petersen, F. F.; Chen, L.
H.; Abbey, D. E. (2000). Relationships of mortality with the fine
and coarse fractions of long-term ambient PM10
concentrations in nonsmokers. J. Exposure Anal. Environ. Epidemiol.
10:427-436.
Miller, F.J.; Gardner, D.E.; Graham, J.A.; Lee, R.E.; Wilson, W.E.;
Bachmann, J.D. (1979) Size considerations for establishing a
standard for inhalable particles. J Air Pollution Control Assoc.
29:610-615.
Molenar, J.V. (2000). Visibility Science and Trends in the Lake
Tahoe Basin: 1989-1998. Report by Air Resource Specialists, Inc., to
Tahoe Regional Planning Agency. February 15, 2000.
Monn, C.; Becker, S. (1999). Cytotoxicity and induction of
proinflammatory cytokines from human monocytes exposed to fine
(PM2.5) and coarse particles (PM10-2.5) in
outdoor and indoor air. Toxicol. Appl. Pharmacol. 155: 245-252.
Moolgavkar, S. H. (2000c). Air pollution and hospital admissions for
chronic obstructive pulmonary disease in three metropolitan areas of
the United States. Inhalation Toxicol. 12 (Suppl. 4):75-90.
Moolgavkar, S. H. (2003). Air pollution and daily deaths and
hospital admissions in Los Angeles and Cook counties. In: Revised
analyses of time-series studies of air pollution and health. Special
report. Boston, MA: Health Effects Institute; pp. 183-198.
Available: http://www.healtheffects.org/news.htm. May 16, 2003.

National Academy of Sciences (2002). Estimating the Public Health
Benefits of Proposed Air Pollution Regulations. Washington, D.C.:
The National Academy Press. Available: http://www.nap.edu/books/0309086094/html/
.

National Research Council (1993). Protecting Visibility in National
Parks and Wilderness Areas. National Academy of Sciences Committee
on Haze in National Parks and Wilderness Areas. National Academy
Press: Washington, DC.
National Science and Technology Council (1998). National acid
precipitation

assessment program biennial report to Congress: an integrated
assessment; executive summary. Silver Spring, MD: U.S. Department of
Commerce, National Oceanic and Atmospheric Administration.
Available: http://www.nnic.noaa.gov/CENR/NAPAP/NAPAP_96.htm.

November 24, 1999.
Nauenberg, E.; Basu, K. (1999). Effect of insurance coverage on the
relationship between asthma hospitalizations and exposure to air
pollution. Public Health Rep. 114: 135-148.
Neas, L. M.; Dockery, D. W.; Koutrakis, P.; Tollerud, D. J.;
Speizer, F. E. (1995). The association of ambient air pollution with
twice daily peak expiratory flow rate measurements in children. Am.
J. Epidemiol. 141: 111-122.
Neas, L. M.; Dockery, D. W.; Burge, H.; Koutrakis, P.; Speizer, F.
E. (1996). Fungus spores, air pollutants, and other determinants of
peak expiratory flow rate in children. Am. J. Epidemiol. 143: 797-
807.
Neas, L. M.; Dockery, D. W.; Koutrakis, P.; Speizer, F. E. (1999).
Fine particles and peak flow in children: acidity versus mass.
Epidemiology 10:550-553.
New Zealand Ministry for the Environment. (2000). Proposals for
Revised and New Ambient Air Quality Guidelines: Discussion Document.
Air Quality Report No. 16. December.
New Zealand National Institute of Water & Atmospheric Research
(NIWAR) (2000a). Visibility in New Zealand: Amenity Value,
Monitoring, Management and Potential Indicators. Air Quality
Technical Report 17. Prepared for New Zealand Ministry for the
Environment. Draft report.
New Zealand National Institute of Water & Atmospheric Research
(NIWAR) (2000b). Visibility in New Zealand: National Risk
Assessment. Air Quality Technical Report 18. Prepared for New
Zealand Ministry for the Environment. Draft report.
Ostro, B. (1995). Fine particulate air pollution and mortality in
two Southern California counties. Environ. Res. 70: 98-104.
Ostro, B. D.; Lipsett, M. J.; Mann, J. K.; Braxton-Owens, H.; White,
M. C. (1995). Air pollution and asthma exacerbations among African-
American children in Los Angeles. Inhalation Toxicol. 7:711-722.
Ostro, B. D.; Broadwin, R.; Lipsett, M. J. (2000). Coarse and fine
particles and daily mortality in the Coachella Valley, CA: a follow-
up study. J. Exposure Anal. Environ. Epidemiol. 10:412-419.
Ostro, B. D.; Broadwin, R.; Lipsett, M. J. (2003). Coarse particles
and daily mortality in Coachella Valley, California. In: Revised
analyses of time-series studies of air pollution and health. Special
report. Boston, MA: Health Effects Institute; pp. 199-204.
Available: http://www.healtheffects.org/Pubs/TimeSeries.pdf. October

18, 2004.
Papp, M.; Eberly, S.; Hanley, T.; Watkins, N.; Barden, H.; Noah, G.;
Bermudez, R.; Eden, R.; Franks, B.; Johnson, A. Marriner, R.;
Michel, E. (2002). Evaluation of Filter Recovery Period for the
Determination of Fine Particulate Matter as PM2.5 in the
Atmosphere. EPA-OAQPS Test Report. Available: http://www.epa.gov/ttn/amtic/files/ambient/pm25/qa/initdraft.pdf
.

Peters, A.; Liu, E.; Verrier, R. L.; Schwartz, J.; Gold, D. R.;
Mittleman, M.; Baliff, J.; Oh, J. A.; Allen, G.; Monahan, K.;
Dockery, D. W. (2000). Air pollution and incidence of cardiac
arrhythmia. Epidemiology 11:11-17.
Peters, A.; Dockery, D. W.; Muller, J. E.; Mittleman, M. A. (2001).
Increased particulate air pollution and the triggering of myocardial
infarction. Circulation 103:2810-2815.
Peters, J. M.; Avol, E.; Navidi, W.; London, S. J.; Gauderman, W.
J.; Lurmann, F.; Linn, W. S.; Margolis, H.; Rappaport, E.; Gong, H.,
Jr.; Thomas, D. C. (1999a). A study of twelve southern California
communities with differing levels and types of air pollution. I.
Prevalence of respiratory morbidity. Am. J. Respir. Crit. Care Med.
159: 760-767.
Peters, J. M.; Avol, E.; Navidi, W.; London, S. J.; Gauderman, W.
J.; Lurmann, F.; Linn, W. S.; Margolis, H.; Rappaport, E.; Gong, H.,
Jr.; Thomas, D. C. (1999b). A study of twelve southern California
communities with differing levels and types of air pollution. II.
Effects on pulmonary function. Am. J. Respir. Crit. Care Med. 159:
768-775.
Pope, C. A., III. (1989). Respiratory disease associated with
community air pollution and a steel mill, Utah Valley. Am. J. Public
Health 79: 623-628.
Pope, C. A., III. (1991). Respiratory hospital admissions associated
with PM10 pollution in Utah, Salt Lake, and Cache
Valleys. Arch. Environ. Health 46: 90-97.
Pope, C. A., III; Schwartz, J.; Ransom, M. R. (1992). Daily
mortality and PM10 pollution in Utah valley. Arch.
Environ. Health 47: 211-217.
Pope, C. A., III; Thun, M. J.; Namboodiri, M. M.; Dockery, D. W.;
Evans, J. S.; Speizer, F. E.; Heath, C. W., Jr. (1995). Particulate
air pollution as a predictor of mortality in a prospective study of
U.S. adults. Am. J. Respir. Crit. Care Med. 151: 669-674.
Pope, C. A., III; Hill, R. W.; Villegas, G. M. (1999). Particulate
air pollution and daily mortality on Utah's Wasatch Front. Environ.
Health Perspect. 107: 567-573.
Pope, C. A., III; Burnett, R. T.; Thun, M. J.; Calle, E. E.;
Krewski, D.; Ito, K.; Thurston, G. D. (2002). Lung cancer,
cardiopulmonary mortality, and long-term exposure to fine
particulate air pollution. J. Am. Med. Assoc. 287:1132-1141.
Post, E.; Deck, L.; Larntz, K.; Hoaglin. D. (2001). An application
of an empirical Bayes estimation technique to the estimation of
mortality related to short-term exposure to particulate matter. Risk
Anal. 21(5): 837-842.
Raizenne, M.; Neas, L. M.; Damokosh, A. I.; Dockery, D. W.;
Spengler, J. D.; Koutrakis, P.; Ware, J. H.; Speizer, F. E. (1996).
Health effects of acid aerosols on North American children:
pulmonary function. Environ. Health Perspect. 104: 506-514.
Rogge, W.F.; Hildemann, L.M.; Mazurek, M.A.; Cass, G.R.; Simoneit,
B.R.T. (1993). Sources of fine organic aerosol. 3. Road dust, tire
debris, and organometallic brake lining dust: roads as sources and
sinks. Environ. Sci. Technol. 27:1982-1904.
Rosendahl, T. (2005). Basis for proposed determinations regarding
retention of the existing 24-hour PM10 standard.
Memorandum to the PM NAAQS review docket, EPA-HQ-OAR-2001-0017.
December 20, 2005.
Ross, M. (2005). Updated information on air quality monitoring data
for thoracic coarse particles used in epidemiologic studies.
Memorandum to the PM NAAQS review docket, EPA-HQ-OAR-2001-0017. June
30, 2005.
Ross, M.; Langstaff, J. (2005). Updated statistical information on
air quality data from epidemiologic studies. Memorandum to PM NAAQS
review docket EPA-HQ-OAR-2001-0017. January 31, 2005.
Schlesinger, R.B., Cassee, F. (2003) Atmospheric secondary inorganic
particulate matter: the toxicological perspective as a basis for
health effects risk assessment. Inhalation Toxicol. 15:197-235.
Schmidt. M; Frank, N.; Mintz, D.; Rao, T.; McCluney, L. (2005).
Analyses of particulate matter (PM) data for the PM NAAQS review.
Memorandum to PM NAAQS review docket EPA-HQ-OAR-2001-0017. June 30,
2005.
Schwartz, J. (1997). Air pollution and hospital admissions for
cardiovascular disease in Tucson. Epidemiology 8: 371-377.
Schwartz, J. (2003a). Daily deaths associated with air pollution in
six U.S. cities and short-term mortality displacement in Boston. In:
Revised analyses of time-series studies of air pollution and health.
Special report. Boston, MA: Health Effects Institute; pp. 219-226.
Available: http://www.healtheffects.org/Pubs/TimeSeries.pdf. October

18, 2004.
Schwartz, J. (2003b). Airborne particles and daily deaths in 10 U.S.
cities. In: Revised analyses of time-series studies of air pollution
and health. Special report. Boston, MA: Health Effects Institute;
pp. 211-218. Available: http://www.healtheffects.org/Pubs/TimeSeries.pdf.
 October 18, 2004.

Schwartz, J.; Dockery, D. W.; Neas, L. M. (1996). Is daily mortality
associated specifically with fine particles? J. Air Waste Manage.
Assoc. 46:927-939.
Schwartz, J.; Norris, G.; Larson, T.; Sheppard, L.; Claiborne, C.;
Koenig, J. (1999). Episodes of high coarse particle concentrations
are not associated with increased mortality. Environ. Health
Perspect. 107: 339-342.
Schwartz, J.; Neas, L. M. (2000). Fine particles are more strongly
associated than coarse particles with acute respiratory health
effects in schoolchildren. Epidemiology 11:6-10.

Science Advisory Board (2004). Advisory for plans on health effects
analysis in the analytical plan for EPA's second prospective
analysis--benefits and costs of the clean air act, 1990-2000.
Advisory by the Health Effects Subcommittee of the Advisory Council
for Clean Air Compliance Analysis. EPA SAB Council--ADV-04-002.
March, 2004. Available: http://www.epa.gov/science1/pdf/council_adv_04002.pdf
.

Sheppard, L. (2003). Ambient air pollution and nonelderly asthma
hospital admissions in Seattle, Washington, 1987-1994. In: Revised
analyses of time-series studies of air pollution and health. Special
report. Boston, MA: Health Effects Institute; pp. 227-230.
Available: http://www.healtheffects.org/Pubs/TimeSeries.pdf. October

18, 2004.
Smith, R. L.; Spitzner, D.; Kim, Y.; Fuentes, M. (2000). Threshold
dependence of mortality effects for fine and coarse particles in
Phoenix, Arizona. J. Air Waste Manage. Assoc. 50: 1367-1379.
Soukup, J. M.; Becker, S. (2001). Human alveolar macrophage
responses to air pollution particulates are associated with
insoluble components of coarse material, including particulate
endotoxin. Toxicol. Appl. Pharmacol. 171: 20-26.
Spengler, J.D., Thurston, G.D. (1983). Mass and Elemental
Composition of Fine and Coarse Particles in Six U.S. Cities. J. Air
& Waste Manage. Assoc. 33: 1162-1171.
State Government of Victoria, Australia (2000a). Draft Variation to
State Environment Protection Policy (Air Quality Management) and
State Environment Protection Policy (Ambient Air Quality) and Draft
Policy Impact Assessment. Environment Protection Authority.
Publication 728. Southbank, Victoria.
State Government of Victoria, Australia (2000b). Year in Review.
Environment Protection Authority. Southbank, Victoria.
Steerenberg, P. A.; Withagen, C. E.; Dormans, J. A. M. A.; Van
Dalen, W. J.; Van Loveren, H.; Casee, F. R. (2003). Adjuvant
activity of various diesel exhaust and ambient particle in two
allergic models. J. Toxicol. Environ. Health A 66: 1421-1439.
Stieb, D. M.; Beveridge, R. C.; Brook, J. R.; Smith-Doiron, M.;
Burnett, R. T.; Dales, R. E.; Beaulieu, S.; Judek, S.; Mamedov, A.
(2000). Air pollution, aeroallergens and cardiorespiratory emergency
department visits in Saint John, Canada. J. Exposure Anal. Environ.
Epidemiol.: 10: 461-477.
Thurston, G. D.; Ito, K.; Hayes, C. G.; Bates, D. V.; Lippmann, M.
(1994). Respiratory hospital admissions and summertime haze air
pollution in Toronto, Ontario: Consideration of the role of acid
aerosols. Environ. Res. 65:271-290.
Tsai, F. C.; Apte, M. G.; Daisey, J. M. (2000). An exploratory
analysis of the relationship between mortality and the chemical
composition of airborne particulate matter. Inhalation Toxicol. 12
(suppl.): 121-135.
Vanderpool, R.; Hanley, T.; Dimmick, F.; Hunike, E. (2005). Multi-
Site Evaluations of Candidate Methodologies for Determining Coarse
Particulate Matter (PM10-2.5) Concentrations: August
2005. Updated Report Regarding Second-Generation and New
PM10-2.5 Samplers. In press.

List of Subjects in 40 CFR Part 50

    Environmental protection, Air pollution control, Carbon monoxide,
Lead, Nitrogen dioxide, Ozone, Particulate matter, Sulfur oxides.

    Dated: December 20, 2005.
Stephen L. Johnson,
Administrator.
    For the reasons set forth in the preamble, part 50 of chapter 1 of
title 40 of the Code of Federal Regulations is proposed to be amended
as follows:

PART 50--NATIONAL PRIMARY AND SECONDARY AMBIENT AIR QUALITY
STANDARDS

    1. The authority citation for part 50 continues to read as follows:

    Authority: 42 U.S.C. 7401 et seq.

    2. Section 50.3 is revised to read as follows:

Sec.  50.3  Reference conditions.

    All measurements of air quality that are expressed as mass per unit
volume (e.g., micrograms per cubic meter) other than for the
particulate matter (PM2.5 and PM10-2.5) standards
contained in Sec. Sec.  50.7 and 50.13 shall be corrected to a
reference temperature of 25 [deg] C and a reference pressure of 760
millimeters of mercury (1,013.2 millibars). Measurements of
PM2.5 and PM10-2.5 for purposes of comparison to
the standards contained in Sec. Sec.  50.7 and 50.13 shall be reported
based on actual ambient air volume measured at the actual ambient
temperature and pressure at the monitoring site during the measurement
period.
    3. Section 50.6 is amended by adding new paragraphs (d) and (e) to
read as follows:

Sec.  50.6  National primary and secondary ambient air quality
standards for PM10.

* * * * *
    (d) The national primary and secondary 24-hour ambient air quality
standards for particulate matter set forth in paragraph (a) of this
section will no longer apply except in the following areas as of
[effective date of final rule]:
    (1) Birmingham urban area (Jefferson County, AL).
    (2) Maricopa and Pinal Counties; Phoenix planning area (AZ).
    (3) Riverside, Los Angeles, Orange and San Bernardino Counties;
South Coast Air Basin (CA).
    (4) Fresno, Kern, Kings, Tulare, San Joaquin, Stanislaus, Maderia
Counties; San Joaquin Valley planning area (CA).
    (5) San Bernardino County (part); excluding Searles Valley Planning
Area and South Coast Air Basin (CA).
    (6) Riverside County; Coachella Valley Planning Area (CA).
    (7) Simi Valley urban area (CA).
    (8) Lake County; Cities of East Chicago, Hammond, Whiting, and Gary
(IN).
    (9) Wayne County (part) (MI).
    (10) St. Louis urban area (MO).
    (11) Albuquerque urban area (NM).
    (12) Clark County; Las Vegas planning area (NV).
    (13) Columbia urban area (SC).
    (14) El Paso urban area (including those portions in TX and those
portions in NM).
    (15) Salt Lake County (UT).
    (e) The national primary and secondary annual ambient air quality
standards for particulate matter set forth in paragraph (b) of this
section will no longer apply in an area as of [effective date of final
rule.]
    4. A new Sec.  50.13 is added, to read as follows:

Sec.  50.13  National primary and secondary ambient air quality
standards for PM2.5 and PM10-2.5.

    (a) The national primary and secondary ambient air quality
standards for particulate matter are:
    (1) 15.0 micrograms per cubic meter ([mu]g/m3) annual
arithmetic mean concentration, and 35 [mu]g/m3 24-hour
average concentration measured in the ambient air as PM2.5
(particles with an aerodynamic diameter less than or equal to a nominal
2.5 micrometers) by either:
    (i) A reference method based on appendix L of this part and
designated in accordance with part 53 of this chapter; or
    (ii) An equivalent method designated in accordance with part 53 of
this chapter.
    (2)(i) 70 [mu]g/m3 24-hour average concentration
measured in the ambient air as PM10-2.5 (particles with an
aerodynamic diameter less than or equal to a nominal 10 micrometers and
greater than a nominal 2.5 micrometers) by either:
    (A) A reference method based on appendix O of this part and
designated in accordance with part 53 of this chapter; or
    (B) An equivalent method designated in accordance with part 53 of
this chapter.
    (ii) The standard for PM10-2.5 includes any ambient mix
of PM10-2.5 that is dominated by resuspended dust from high-
density traffic on paved roads and

PM generated by industrial sources and construction sources, and
excludes any ambient mix of PM10-2.5 that is dominated by
rural windblown dust and soils and PM generated by agricultural and
mining sources. Agricultural sources, mining sources, and other similar
sources of crustal material shall not be subject to control in meeting
this standard.
    (b) The annual primary and secondary PM2.5 standards are
met when the annual arithmetic mean concentration, as determined in
accordance with appendix N of this part, is less than or equal to 15.0
[mu]g/m3.
    (c) The 24-hour primary and secondary PM2.5 standards
are met when the 98th percentile 24-hour concentration, as determined
in accordance with appendix N of this part, is less than or equal to 35
[mu]g/m3. The 24-hour primary and secondary
PM10-2.5 standards are met when the 98th percentile 24-hour
concentration, as determined in accordance with appendix P of this
part, is less than or equal to 70 [mu]g/m3.
    5. Appendix L to part 50 is amended by:
    a. Revising section 1.1;
    b. Revising the heading of section 7.3.4 and adding introductory
text; revising paragraph (a) of section <IP_ADDRESS>, adding section
<IP_ADDRESS>; and revising Table L-1 in section 7.4.19;
    c. Revising section 8.3.6;
    d. Revising the first sentence in section 10.10 and revising
section 10.13; and
    e. Revising reference 2 in section 13.0. The revisions and addition
read as follows:

Appendix L to Part 50--Reference Method for the Determination of Fine
Particulate Matter as PM2.5 in the Atmosphere

    1.0 Applicability.
    1.1 This method provides for the measurement of the mass
concentration of fine particulate matter having an aerodynamic
diameter less than or equal to a nominal 2.5 micrometers
(PM2.5) in ambient air over a 24-hour period for purposes
of determining whether the primary and secondary national ambient
air quality standards for fine particulate matter specified in Sec.
50.7 and Sec.  50.13 of this part are met. The measurement process
is considered to be nondestructive, and the PM2.5 sample
obtained can be subjected to subsequent physical or chemical
analyses. Quality assessment procedures are provided in part 58,
appendix A of this chapter, and quality assurance guidance are
provided in references 1, 2, and 3 in section 13.0 of this appendix.
* * * * *
    7.3 Design specifications. * * *
* * * * *
    7.3.4 Particle size separator. The sampler shall be configured
with either one of the two alternative particle size separators
described in this section 7.3.4. One separator is an impactor-type
separator (WINS impactor) described in sections <IP_ADDRESS>, <IP_ADDRESS>,
and <IP_ADDRESS> of this appendix. The alternative separator is a
cyclone-type separator (VSCCTM) described in section
<IP_ADDRESS> of this appendix.
* * * * *
    <IP_ADDRESS> Impactor oil specifications:
    (a) Composition. Dioctyl sebacate (DOS), single-compound
diffusion oil.
* * * * *
    <IP_ADDRESS> The cyclone-type separator is identified as a BGI
VSCCTM Very Sharp Cut Cyclone particle size separator
specified as part of EPA-designated equivalent method EQPM-0202-142
(67 FR 15567, April 2, 2002) and as manufactured by BGI
Incorporated, 58 Guinan Street, Waltham, Massachusetts 20451.
* * * * *
    7.4.19 Data reporting requirements. * * *

                                Table L-1 to Appendix L of Part 50.--Summary of Information to be Provided by the Sampler
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                            Availability                                          Format
                                    Appendix L    ------------------------------------------------------------------------------------------------------
   Information to be provided         section                       End of period  Visual display   Data output     Digital reading
                                     reference       Anytime \1\         \2\             \3\            \4\               \5\                Units
--------------------------------------------------------------------------------------------------------------------------------------------------------
Flow rate, 30 second maximum     <IP_ADDRESS>           [b  ..............  [b  (*)            XX.X                L/min
 interval.                                          <]                   <]
Flow rate, average for the       <IP_ADDRESS>           (*)             [b  (*)             [b]                   >
                                                                                < ]
Flow rate, CV, for sample        <IP_ADDRESS>           (*)             [b  (*)             [b]                   >
                                                                                < ]
Flow rate, 5-min. average out    <IP_ADDRESS>           [b  [b  [b  [b]   <]   <]   >
                                                                                < ][squf]
Sample volume, total...........  <IP_ADDRESS>           (*)             [b  [b  [b]   <]   >
                                                                                < ]
Temperature, ambient, 30-second  7.4.8             [b  ..............  [b  .............  XX.X                [deg]C
 interval.                                          <]                   <]
Temperature, ambient, min.,      7.4.8             (*)             [b  [b  [b]   <]   >
 period.                                                                                < ][squf]
Baro. pressure, ambient, 30-     7.4.9             [b  ..............  [b  .............  XXX                 mm Hg
 second interval.                                   <]                   <]
Baro. pressure, ambient, min.,   7.4.9             (*)             [b  [b  [b]   <]   >
 period.                                                                                < ][squf]
Filter temperature, 30-second    7.4.11            [b  ..............  [b  .............  XX.X                [deg]C
 interval.                                          <]                   <]
Filter temp. differential, 30-   7.4.11            (*)             [b  [b  [b]   <]   >
 (FLAG \6\).                                                                                < ][squf]
Filter temp., maximum            7.4.11            (*)             (*)             (*)             (*)            X.X, YY/MM/DD       [deg]C Yr/Mon/Day
 differential from ambient,                                                                                HH.mm               Hrs.min
 date, time of occurrence.
Date and Time..................  7.4.12            [b  ..............  [b  .............  YY/MM/DD HH.mm      Yr/Mon/Day Hrs.min
                                                    <]                   <]
Sample start and stop time       7.4.12            [b  [b  [b  [b]   <]   <]   >
                                                                                < ]
Sample period start time.......  7.4.12            ..............  [b  [b  [b]   <]   >
                                                                                < ]
Elapsed sample time............  7.4.13            (*)             [b  [b  [b]   <]   >
                                                                                < ]
Elapsed sample time, out of      7.4.13            ..............  [b  [b  [b]   <]   >
                                                                                < ][squf]
Power interruptions <=1 min.,    <IP_ADDRESS>          (*)             [b  (*)             [b]                   >   etc* * *
                                                                                < ]
User-entered information, such   7.4.16            [b  [b  [b  [b]   <]   <]   >
 identification.                                                                                < ][squf]
--------------------------------------------------------------------------------------------------------------------------------------------------------
[b] Provision of this information is required.

* Provision of this information is optional. If information related to the entire sample period is optionally provided prior to the end of the sample
  period, the value provided should be the value calculated for the portion of the sampler period completed up to the time the information is provided.
[squf] Indicates that this information is also required to be provided to the Air Quality System (AQS) data bank; see Sec.   58.16 of this chapter. For
  ambient temperature and barometric pressure, only the average for the sample period must be reported.

    1. Information is required to be available to the operator at
any time the sampler is operating, whether sampling or not.
    2. Information relates to the entire sampler period and must be
provided following the end of the sample period until reset manually
by the operator or automatically by the sampler upon the start of a
new sample period.
    3. Information shall be available to the operator visually.
    4. Information is to be available as digital data at the
sampler's data output port specified in section 7.4.16 of this
appendix following the end of the sample period until reset manually
by the operator or automatically by the sampler upon the start of a
new sample period.
    5. Digital readings, both visual and data output, shall have not
less than the number of significant digits and resolution specified.
    6. Flag warnings may be displayed to the operator by a single
flag indicator or each flag may be displayed individually. Only a
set (on) flag warning must be indicated; an off (unset) flag may be
indicated by the absence of a flag warning. Sampler users should
refer to section 10.12 of this appendix regarding the validity of
samples for which the sampler provided an associated flag warning.
* * * * *
    8.3 Weighing procedure.
* * * * *
    8.3.6 The post-sampling conditioning and weighing shall be
completed within 240 hours (10 days) after the end of the sample
period, unless the filter sample is maintained at temperatures below
the average ambient temperature during sampling (or 4[deg]C or below
for average sampling temperatures less than 4[deg]C) during the time
between retrieval from the sampler and the start of the
conditioning, in which case the period shall not exceed 30 days.
Reference 2 in section 13.0 of this appendix has additional guidance
on transport of cooled filters.
* * * * *
    10.0 PM2.5 Measurement Procedure. * * *
* * * * *
    10.10 Within 177 hours (7 days, 9 hours) of the end of the
sample collection period, the filter, while still contained in the
filter cassette, shall be carefully removed from the sampler,
following the procedure provided in the sampler operation or
instruction manual and the quality assurance program, and placed in
a protective container. * * *
* * * * *
    10.13 After retrieval from the sampler, the exposed filter
containing the PM2.5 sample should be transported to the
filter conditioning environment as soon as possible, ideally to
arrive at the conditioning environment within 24 hours for
conditioning and subsequent weighing. During the period between
filter retrieval from the sampler and the start of the conditioning,
the filter shall be maintained as cool as practical and continuously
protected from exposure to temperatures over 25[deg]C to protect the
integrity of the sample and minimize loss of volatile components
during transport and storage. See section 8.3.6 of this appendix
regarding time limits for completing the post-sampling weighing. See
reference 2 in section 13.0 of this appendix for additional guidance
on transporting filter samplers to the conditioning and weighing
laboratory.
* * * * *
    13.0 References.
* * * * *
    2. Quality Assurance Guidance Document 2.12. Monitoring
PM2.5 in Ambient Air Using Designated Reference or Class
I Equivalent Methods. U.S. EPA, National Exposure Research
Laboratory. Research Triangle Park, NC, November 1988 or later
edition. Currently available at: http://www.epa.gov/ttn/amtic/pmqainf.html
.

* * * * *
    6. Appendix N to part 50 is revised to read as follows:

Appendix N to Part 50--Interpretation of the National Ambient Air
Quality Standards for PM2.5

    1. General.
    (a) This appendix explains the data handling conventions and
computations necessary for determining when the annual and 24-hour
primary and secondary national ambient air quality standards (NAAQS)
for PM2.5 specified in Sec.  50.7 and Sec.  50.13 of this
part are met. PM2.5, defined as particles with an
aerodynamic diameter less than or equal to a nominal 2.5
micrometers, is measured in the ambient air by a Federal reference
method (FRM) based on appendix L of this part, as applicable, and
designated in accordance with part 53 of this chapter, or by a
Federal equivalent method (FEM) designated in accordance with part
53 of this chapter. Data handling and computation procedures to be
used in making comparisons between reported PM2.5
concentrations and the levels of the PM2.5 NAAQS are
specified in the following sections.
    (b) Data resulting from exceptional events, for example
structural fires or high winds, may be given special consideration.
In some cases, it may be appropriate to exclude these data in whole
or part because they could result in inappropriate values to compare
with the levels of the PM2.5 NAAQS. In other cases, it
may be more appropriate to retain the data for comparison with the
levels of the PM2.5 NAAQS and then for EPA to formulate
the appropriate regulatory response.
    (c) The terms used in this appendix are defined as follows:
    Annual mean refers to a weighted arithmetic mean, based on
quarterly means, as defined in section 4.4 of this appendix.
    Daily values for PM2.5 refers to the 24-hour average
concentrations of PM2.5 calculated (averaged from hourly
measurements) or measured from midnight to midnight (local standard
time).
    Designated monitors are those monitoring sites designated in a
State or local agency PM Monitoring Network Description in
accordance with part 58 of this chapter.
    Design values are the metrics (i.e., statistics) that are
compared to the NAAQS levels to determine compliance, calculated as
shown in section 4 of this appendix:
    (1) The 3-year average of annual means for a single monitoring
site or a group of monitoring sites (referred to as the ``annual
standard design value''). If spatial averaging has been approved by
EPA for a group of sites which meet the criteria specified in
section 2(b) of this appendix and section 4.7.5 of appendix D of 40
CFR part 58, then 3 years of spatially averaged annual means will be
averaged to derive the annual standard design value for that group
of sites (further referred to as the ``spatially averaged annual
standard design value''). Otherwise, the annual standard design
value will represent the 3-year average of annual means for a single
site (further referred to as the ``single site annual standard
design value'').
    (2) The 3-year average of annual 98th percentile 24-hour average
values recorded at each monitoring site (referred to as the ``24-
hour standard design value'').
    98th percentile is the daily value out of a year of
PM2.5 monitoring data below which 98 percent of all daily
values fall.
    Year refers to a calendar year.
    2.0 Monitoring Considerations.
    (a) Section 58.30 of this chapter specifies which monitoring
locations are eligible for making comparisons with the
PM2.5 standards.
    (b) To qualify for spatial averaging, monitoring sites must meet
the criterion specified in section 4.7.5 of appendix D of 40 CFR
part 58 as well as the following requirements:
    (1) The annual mean concentration at each site shall be within
10 percent of the spatially averaged annual mean.
    (2) The daily values for each site pair shall yield a
correlation coefficient of at least 0.9 for each calendar quarter.
    (3) All of the monitoring sites should principally be affected
by the same major emission sources of PM2.5. This can be
demonstrated by site-specific chemical speciation profiles
confirming all major component concentration averages to be within
10 percent for each calendar quarter.
    (4) The requirements in paragraphs (b)(1) through (3) of this
section shall be met for 3 consecutive years in order to produce a
valid spatially averaged annual standard design value. Otherwise,
the individual (single) site annual standard design values shall be
compared directly to the level of the annual NAAQS.

    (c) Section 58.12 of this chapter specifies the required minimum
frequency of sampling for PM2.5. Exceptions to the
specified sampling frequencies, such as a reduced frequency during a
season of expected low concentrations (i.e., ``seasonal sampling''),
are subject to the approval of EPA. Annual 98th percentile values
are to be calculated according to equation 6 in section 4.5 of this
appendix when a site operates on a ``seasonal sampling'' schedule.
    3.0 Requirements for Data Used for Comparisons With the PM2.5
NAAQS and Data Reporting Considerations.
    (a) Except as otherwise provided in this appendix, only valid
FRM/FEM PM2.5 data required to be submitted to EPA's Air
Quality System (AQS) shall be used in the design value calculations.
    (b) PM2.5 measurement data (typically hourly for
continuous instruments and daily for filter-based instruments) shall
be reported to AQS in micrograms per cubic meter ([mu]g/
m3) to one decimal place, with additional digits to the
right being truncated.
    (c) Block 24-hour averages shall be computed from available
hourly PM2.5 concentration data for each corresponding
day of the year and the result shall be stored in the first, or
start, hour (i.e., midnight, hour `0') of the 24-hour period. A 24-
hour average shall be considered valid if at least 75 percent (i.e.,
18) of the hourly averages for the 24-hour period are available. In
the event that less than all 24 hourly averages are available (i.e.,
less than 24, but at least 18), the 24-hour average shall be
computed on the basis of the hours available using the number of
available hours as the divisor (e.g., 19). 24-hour periods with
seven or more missing hours shall be considered valid if, after
substituting zero for all missing hourly concentrations, the 24-hour
average concentration is greater than the level of the standard. The
computed 24-hour average PM2.5 concentrations shall be
reported to one decimal place (the insignificant digits to the right
of the third decimal place are truncated, consistent with the data
handling procedures for the reported data).
    (d) Except for calculation of spatially averaged annual means
and spatially averaged annual standard design values, all other
calculations shown in this appendix shall be implemented on a site-
level basis. Site level data shall be processed as follows:
    (1) The default dataset for a site shall consist of the measured
concentrations recorded from the designated primary FRM/FEM monitor.
The primary monitor shall be designated in the appropriate State or
local agency PM Monitoring Network Description.
    (2) Data for the primary monitor shall be augmented as necessary
with data from collocated FRM/FEM monitors. If a valid 24-hour
measurement is not produced from the primary monitor for a
particular required sampling day, but a valid sample is generated by
a collocated FRM/FEM instrument (and recorded in AQS), then that
collocated value shall be considered part of the site data record.
If more than one valid collocated FRM/FEM value is available, the
average of those valid collocated values shall be used as the site
value for the day.
    4.0 Comparisons with the PM2.5 NAAQS.
    4.1 Annual PM2.5 NAAQS.
    (a) The annual PM2.5 NAAQS is met when the annual
standard design value is less than or equal to 15.0 micrograms per
cubic meter ([mu]g/m3).
    (b) For single site comparisons, 3 years of valid annual means
are required to produce a valid annual standard design value. In the
case of spatial averaging, 3 years of valid spatially averaged
annual means are required to produce a valid annual standard design
value. Designated sites with less than 3 years of data shall be
included in annual spatial averages for those years that data
completeness requirements are met. A year meets data completeness
requirements when at least 75 percent of the scheduled sampling days
for each quarter have valid data. However, years with high
concentrations and at least 11 samples in each quarter shall be
considered valid, notwithstanding quarters with less than complete
data, if the resulting annual mean, spatially averaged annual mean
concentration, or resulting annual standard design value
concentration (rounded according to the conventions of section 4.3
of this appendix) is greater than the level of the standard.
Furthermore, where the explicit 11 sample per quarter requirement is
not met, the site annual mean shall still be considered valid if, by
substituting a low value (described below) for the missing data in
the deficient quarters (substituting enough to meet the 11 sample
minimum), the computation still yields a recalculated annual mean,
spatially averaged annual mean concentration, or annual standard
design value concentration over the level of the standard. The low
value used for this substitution test shall be the lowest reported
value in the site data record for that calendar quarter over the
most recent 3-year period. If an annual mean is deemed complete
using this test, the original annual mean (without substituted low
values) shall be considered the official mean value for this site,
not the result of the recalculated test using the low values.
    (c) The use of less than complete data is subject to the
approval of EPA, which may consider factors such as monitoring site
closures/moves, monitoring diligence, and nearby concentrations in
determining whether to use such data.
    (d) The equations for calculating the annual standard design
values are given in section 4.4 of this appendix.
    4.2 24-Hour PM2.5 NAAQS.
    (a) The 24-hour PM2.5 NAAQS is met when the 24-hour
standard design value at each monitoring site is less than or equal
to 35 [mu]g/m3. This comparison shall be based on 3
consecutive, complete years of air quality data. A year meets data
completeness requirements when at least 75 percent of the scheduled
sampling days for each quarter have valid data. However, years with
high concentrations shall be considered valid, notwithstanding
quarters with less than complete data (even quarters with less than
11 samples), if the resulting annual 98th percentile value or
resulting 24-hour standard design value (rounded according to the
conventions of section 4.3 of this appendix) is greater than the
level of the standard.
    (b) The use of less than complete data is subject to the
approval of EPA which may consider factors such as monitoring site
closures/moves, monitoring diligence, and nearby concentrations in
determining whether to use such data.
    (c) The equations for calculating the 24-hour standard design
values are given in section 4.5 of this appendix.
    4.3 Rounding Conventions. For the purposes of comparing
calculated values to the applicable level of the standard, it is
necessary to round the final results of the calculations described
in sections 4.4 and 4.5 of this appendix. Results for all
intermediate calculations shall not be rounded.
    (a) Annual PM2.5 standard design values shall be
rounded to the nearest 0.1 [mu]g/m3 (decimals 0.05 and
greater are rounded up to the next 0.1, and any decimal lower than
0.05 is rounded down to the nearest 0.1).
    (b) 24-hour PM2.5 standard design values shall be
rounded to the nearest 1 [mu]g/m3 (decimals 0.5 and
greater are rounded up to the nearest whole number, and any decimal
lower than 0.5 is rounded down to the nearest whole number).
    4.4 Equations for the Annual PM2.5 NAAQS.
    (a) An annual mean value for PM2.5 is determined by
first averaging the daily values of a calendar quarter using
equation 1 of this appendix:
[GRAPHIC] [TIFF OMITTED] TP17JA06.052

Where:

xq, y, s = the mean for quarter q of year y for site s;
nq = the number of monitored values in the quarter; and
xi, q, y, s = the ith value in quarter q for