Appendix L to Part 50 - Reference Method for the Determination of Fine Particulate Matter as PM2.5 in the Atmosphere
40:2.0.1.1.1.0.1.20.13 : Appendix L
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 § 50.7 and §
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.
1.2 This method will be considered a reference method for
purposes of part 58 of this chapter only if:
(a) The associated sampler meets the requirements specified in
this appendix and the applicable requirements in part 53 of this
chapter, and
(b) The method and associated sampler have been designated as a
reference method in accordance with part 53 of this chapter.
1.3 PM2.5 samplers that meet nearly all specifications set forth
in this method but have minor deviations and/or modifications of
the reference method sampler will be designated as “Class I”
equivalent methods for PM2.5 in accordance with part 53 of this
chapter.
2.0 Principle.
2.1 An electrically powered air sampler draws ambient air at a
constant volumetric flow rate into a specially shaped inlet and
through an inertial particle size separator (impactor) where the
suspended particulate matter in the PM2.5 size range is separated
for collection on a polytetrafluoroethylene (PTFE) filter over the
specified sampling period. The air sampler and other aspects of
this reference method are specified either explicitly in this
appendix or generally with reference to other applicable
regulations or quality assurance guidance.
2.2 Each filter is weighed (after moisture and temperature
conditioning) before and after sample collection to determine the
net gain due to collected PM2.5. The total volume of air sampled is
determined by the sampler from the measured flow rate at actual
ambient temperature and pressure and the sampling time. The mass
concentration of PM2.5 in the ambient air is computed as the total
mass of collected particles in the PM2.5 size range divided by the
actual volume of air sampled, and is expressed in micrograms per
cubic meter of air (µg/m 3).
3.0 PM2.5 Measurement Range.
3.1 Lower concentration limit. The lower detection limit
of the mass concentration measurement range is estimated to be
approximately 2 µg/m 3, based on noted mass changes in field blanks
in conjunction with the 24 m 3 nominal total air sample volume
specified for the 24-hour sample.
3.2 Upper concentration limit. The upper limit of the
mass concentration range is determined by the filter mass loading
beyond which the sampler can no longer maintain the operating flow
rate within specified limits due to increased pressure drop across
the loaded filter. This upper limit cannot be specified precisely
because it is a complex function of the ambient particle size
distribution and type, humidity, the individual filter used, the
capacity of the sampler flow rate control system, and perhaps other
factors. Nevertheless, all samplers are estimated to be capable of
measuring 24-hour PM2.5 mass concentrations of at least 200 µg/m 3
while maintaining the operating flow rate within the specified
limits.
3.3 Sample period. The required sample period for PM2.5
concentration measurements by this method shall be 1,380 to 1500
minutes (23 to 25 hours). However, when a sample period is less
than 1,380 minutes, the measured concentration (as determined by
the collected PM2.5 mass divided by the actual sampled air volume),
multiplied by the actual number of minutes in the sample period and
divided by 1,440, may be used as if it were a valid concentration
measurement for the specific purpose of determining a violation of
the NAAQS. This value assumes that the PM2.5 concentration is zero
for the remaining portion of the sample period and therefore
represents the minimum concentration that could have been measured
for the full 24-hour sample period. Accordingly, if the value thus
calculated is high enough to be an exceedance, such an exceedance
would be a valid exceedance for the sample period. When reported to
AIRS, this data value should receive a special code to identify it
as not to be commingled with normal concentration measurements or
used for other purposes.
4.0 Accuracy.
4.1 Because the size and volatility of the particles making up
ambient particulate matter vary over a wide range and the mass
concentration of particles varies with particle size, it is
difficult to define the accuracy of PM2.5 measurements in an
absolute sense. The accuracy of PM2.5 measurements is therefore
defined in a relative sense, referenced to measurements provided by
this reference method. Accordingly, accuracy shall be defined as
the degree of agreement between a subject field PM2.5 sampler and a
collocated PM2.5 reference method audit sampler operating
simultaneously at the monitoring site location of the subject
sampler and includes both random (precision) and systematic (bias)
errors. The requirements for this field sampler audit procedure are
set forth in part 58, appendix A of this chapter.
4.2 Measurement system bias. Results of collocated
measurements where the duplicate sampler is a reference method
sampler are used to assess a portion of the measurement system bias
according to the schedule and procedure specified in part 58,
appendix A of this chapter.
4.3 Audits with reference method samplers to determine system
accuracy and bias. According to the schedule and procedure
specified in part 58, appendix A of this chapter, a reference
method sampler is required to be located at each of selected PM2.5
SLAMS sites as a duplicate sampler. The results from the primary
sampler and the duplicate reference method sampler are used to
calculate accuracy of the primary sampler on a quarterly basis,
bias of the primary sampler on an annual basis, and bias of a
single reporting organization on an annual basis. Reference 2 in
section 13.0 of this appendix provides additional information and
guidance on these reference method audits.
4.4 Flow rate accuracy and bias. Part 58, appendix A of
this chapter requires that the flow rate accuracy and bias of
individual PM2.5 samplers used in SLAMS monitoring networks be
assessed periodically via audits of each sampler's operational flow
rate. In addition, part 58, appendix A of this chapter requires
that flow rate bias for each reference and equivalent method
operated by each reporting organization be assessed quarterly and
annually. Reference 2 in section 13.0 of this appendix provides
additional information and guidance on flow rate accuracy audits
and calculations for accuracy and bias.
5.0 Precision. A data quality objective of 10 percent
coefficient of variation or better has been established for the
operational precision of PM2.5 monitoring data.
5.1 Tests to establish initial operational precision for each
reference method sampler are specified as a part of the
requirements for designation as a reference method under § 53.58 of
this chapter.
5.2 Measurement System Precision. Collocated sampler
results, where the duplicate sampler is not a reference method
sampler but is a sampler of the same designated method as the
primary sampler, are used to assess measurement system precision
according to the schedule and procedure specified in part 58,
appendix A of this chapter. Part 58, appendix A of this chapter
requires that these collocated sampler measurements be used to
calculate quarterly and annual precision estimates for each primary
sampler and for each designated method employed by each reporting
organization. Reference 2 in section 13.0 of this appendix provides
additional information and guidance on this requirement.
6.0 Filter for PM2.5 Sample Collection. Any filter
manufacturer or vendor who sells or offers to sell filters
specifically identified for use with this PM2.5 reference method
shall certify that the required number of filters from each lot of
filters offered for sale as such have been tested as specified in
this section 6.0 and meet all of the following design and
performance specifications.
6.1 Size. Circular, 46.2 mm diameter ±0.25 mm.
6.2 Medium. Polytetrafluoroethylene (PTFE Teflon), with
integral support ring.
6.3 Support ring. Polymethylpentene (PMP) or equivalent
inert material, 0.38 ±0.04 mm thick, outer diameter 46.2 mm ±0.25
mm, and width of 3.68 mm (±0.00, −0.51 mm).
6.4 Pore size. 2 µm as measured by ASTM F 316-94.
6.5 Filter thickness. 30 to 50 µm.
6.6 Maximum pressure drop (clean filter). 30 cm H2O
column @ 16.67 L/min clean air flow.
6.7 Maximum moisture pickup. Not more than 10 µg weight
increase after 24-hour exposure to air of 40 percent relative
humidity, relative to weight after 24-hour exposure to air of 35
percent relative humidity.
6.8 Collection efficiency. Greater than 99.7 percent, as
measured by the DOP test (ASTM D 2986-91) with 0.3 µm particles at
the sampler's operating face velocity.
6.9 Filter weight stability. Filter weight loss shall be
less than 20 µg, as measured in each of the following two tests
specified in sections 6.9.1 and 6.9.2 of this appendix. The
following conditions apply to both of these tests: Filter weight
loss shall be the average difference between the initial and the
final filter weights of a random sample of test filters selected
from each lot prior to sale. The number of filters tested shall be
not less than 0.1 percent of the filters of each manufacturing lot,
or 10 filters, whichever is greater. The filters shall be weighed
under laboratory conditions and shall have had no air sample passed
through them, i.e., filter blanks. Each test procedure must include
initial conditioning and weighing, the test, and final conditioning
and weighing. Conditioning and weighing shall be in accordance with
sections 8.0 through 8.2 of this appendix and general guidance
provided in reference 2 of section 13.0 of this appendix.
6.9.1 Test for loose, surface particle contamination.
After the initial weighing, install each test filter, in turn, in a
filter cassette (Figures L-27, L-28, and L-29 of this appendix) and
drop the cassette from a height of 25 cm to a flat hard surface,
such as a particle-free wood bench. Repeat two times, for a total
of three drop tests for each test filter. Remove the test filter
from the cassette and weigh the filter. The average change in
weight must be less than 20 µg.
6.9.2 Test for temperature stability. After weighing each
filter, place the test filters in a drying oven set at 40 °C ±2 °C
for not less than 48 hours. Remove, condition, and reweigh each
test filter. The average change in weight must be less than 20
µg.
6.10 Alkalinity. Less than 25 microequivalents/gram of
filter, as measured by the guidance given in reference 2 in section
13.0 of this appendix.
6.11 Supplemental requirements. Although not required for
determination of PM2.5 mass concentration under this reference
method, additional specifications for the filter must be developed
by users who intend to subject PM2.5 filter samples to subsequent
chemical analysis. These supplemental specifications include
background chemical contamination of the filter and any other
filter parameters that may be required by the method of chemical
analysis. All such supplemental filter specifications must be
compatible with and secondary to the primary filter specifications
given in this section 6.0 of this appendix.
7.0 PM2.5 Sampler.
7.1 Configuration. The sampler shall consist of a sample
air inlet, downtube, particle size separator (impactor), filter
holder assembly, air pump and flow rate control system, flow rate
measurement device, ambient and filter temperature monitoring
system, barometric pressure measurement system, timer, outdoor
environmental enclosure, and suitable mechanical, electrical, or
electronic control capability to meet or exceed the design and
functional performance as specified in this section 7.0 of this
appendix. The performance specifications require that the
sampler:
(a) Provide automatic control of sample volumetric flow rate and
other operational parameters.
(b) Monitor these operational parameters as well as ambient
temperature and pressure.
(c) Provide this information to the sampler operator at the end
of each sample period in digital form, as specified in table L-1 of
section 7.4.19 of this appendix.
7.2 Nature of specifications. The PM2.5 sampler is
specified by a combination of design and performance requirements.
The sample inlet, downtube, particle size discriminator, filter
cassette, and the internal configuration of the filter holder
assembly are specified explicitly by design figures and associated
mechanical dimensions, tolerances, materials, surface finishes,
assembly instructions, and other necessary specifications. All
other aspects of the sampler are specified by required operational
function and performance, and the design of these other aspects
(including the design of the lower portion of the filter holder
assembly) is optional, subject to acceptable operational
performance. Test procedures to demonstrate compliance with both
the design and performance requirements are set forth in subpart E
of part 53 of this chapter.
7.3 Design specifications. Except as indicated in this
section 7.3 of this appendix, these components must be manufactured
or reproduced exactly as specified, in an ISO 9001-registered
facility, with registration initially approved and subsequently
maintained during the period of manufacture. See § 53.1(t) of this
chapter for the definition of an ISO-registered facility. Minor
modifications or variances to one or more components that clearly
would not affect the aerodynamic performance of the inlet,
downtube, impactor, or filter cassette will be considered for
specific approval. Any such proposed modifications shall be
described and submitted to the EPA for specific individual
acceptability either as part of a reference or equivalent method
application under part 53 of this chapter or in writing in advance
of such an intended application under part 53 of this chapter.
7.3.1 Sample inlet assembly. The sample inlet assembly,
consisting of the inlet, downtube, and impactor shall be configured
and assembled as indicated in Figure L-1 of this appendix and shall
meet all associated requirements. A portion of this assembly shall
also be subject to the maximum overall sampler leak rate
specification under section 7.4.6 of this appendix.
7.3.2 Inlet. The sample inlet shall be fabricated as
indicated in Figures L-2 through L-18 of this appendix and shall
meet all associated requirements.
7.3.3 Downtube. The downtube shall be fabricated as
indicated in Figure L-19 of this appendix and shall meet all
associated requirements.
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
7.3.4.1, 7.3.4.2, and 7.3.4.3 of this appendix. The alternative
separator is a cyclone-type separator (VSCC TM) described in
section 7.3.4.4 of this appendix.
7.3.4.1 The impactor (particle size separator) shall be
fabricated as indicated in Figures L-20 through L-24 of this
appendix and shall meet all associated requirements. Following the
manufacture and finishing of each upper impactor housing (Figure
L-21 of this appendix), the dimension of the impaction jet must be
verified by the manufacturer using Class ZZ go/no-go plug gauges
that are traceable to NIST.
7.3.4.2 Impactor filter specifications:
(a) Size. Circular, 35 to 37 mm diameter.
(b) Medium. Borosilicate glass fiber, without binder.
(c) Pore size. 1 to 1.5 micrometer, as measured by ASTM F
316-80.
(d) Thickness. 300 to 500 micrometers.
7.3.4.3 Impactor oil specifications:
(a) Composition. Dioctyl sebacate (DOS), single-compound
diffusion oil.
(b) Vapor pressure. Maximum 2 × 10−8 mm Hg at 25 °C.
(c) Viscosity. 36 to 40 centistokes at 25 °C.
(d) Density. 1.06 to 1.07 g/cm 3 at 25 °C.
(e) Quantity. 1 mL ±0.1 mL.
7.3.4.4 The cyclone-type separator is identified as a BGI VSCC
TM 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.
7.3.5 Filter holder assembly. The sampler shall have a
sample filter holder assembly to adapt and seal to the down tube
and to hold and seal the specified filter, under section 6.0 of
this appendix, in the sample air stream in a horizontal position
below the downtube such that the sample air passes downward through
the filter at a uniform face velocity. The upper portion of this
assembly shall be fabricated as indicated in Figures L-25 and L-26
of this appendix and shall accept and seal with the filter
cassette, which shall be fabricated as indicated in Figures L-27
through L-29 of this appendix.
(a) The lower portion of the filter holder assembly shall be of
a design and construction that:
(1) Mates with the upper portion of the assembly to complete the
filter holder assembly,
(2) Completes both the external air seal and the internal filter
cassette seal such that all seals are reliable over repeated filter
changings, and
(3) Facilitates repeated changing of the filter cassette by the
sampler operator.
(b) Leak-test performance requirements for the filter holder
assembly are included in section 7.4.6 of this appendix.
(c) If additional or multiple filters are stored in the sampler
as part of an automatic sequential sample capability, all such
filters, unless they are currently and directly installed in a
sampling channel or sampling configuration (either active or
inactive), shall be covered or (preferably) sealed in such a way as
to:
(1) Preclude significant exposure of the filter to possible
contamination or accumulation of dust, insects, or other material
that may be present in the ambient air, sampler, or sampler
ventilation air during storage periods either before or after
sampling; and
(2) To minimize loss of volatile or semi-volatile PM sample
components during storage of the filter following the sample
period.
7.3.6 Flow rate measurement adapter. A flow rate
measurement adapter as specified in Figure L-30 of this appendix
shall be furnished with each sampler.
7.3.7 Surface finish. All internal surfaces exposed to
sample air prior to the filter shall be treated electrolytically in
a sulfuric acid bath to produce a clear, uniform anodized surface
finish of not less than 1000 mg/ft 2 (1.08 mg/cm 2) in accordance
with military standard specification (mil. spec.) 8625F, Type II,
Class 1 in reference 4 of section 13.0 of this appendix. This
anodic surface coating shall not be dyed or pigmented. Following
anodization, the surfaces shall be sealed by immersion in boiling
deionized water for not less than 15 minutes. Section 53.51(d)(2)
of this chapter should also be consulted.
7.3.8 Sampling height. The sampler shall be equipped with
legs, a stand, or other means to maintain the sampler in a stable,
upright position and such that the center of the sample air
entrance to the inlet, during sample collection, is maintained in a
horizontal plane and is 2.0 ±0.2 meters above the floor or other
horizontal supporting surface. Suitable bolt holes, brackets,
tie-downs, or other means should be provided to facilitate
mechanically securing the sample to the supporting surface to
prevent toppling of the sampler due to wind.
7.4 Performance specifications.
7.4.1 Sample flow rate. Proper operation of the impactor
requires that specific air velocities be maintained through the
device. Therefore, the design sample air flow rate through the
inlet shall be 16.67 L/min (1.000 m 3/hour) measured as actual
volumetric flow rate at the temperature and pressure of the sample
air entering the inlet.
7.4.2 Sample air flow rate control system. The sampler
shall have a sample air flow rate control system which shall be
capable of providing a sample air volumetric flow rate within the
specified range, under section 7.4.1 of this appendix, for the
specified filter, under section 6.0 of this appendix, at any
atmospheric conditions specified, under section 7.4.7 of this
appendix, at a filter pressure drop equal to that of a clean filter
plus up to 75 cm water column (55 mm Hg), and over the specified
range of supply line voltage, under section 7.4.15.1 of this
appendix. This flow control system shall allow for operator
adjustment of the operational flow rate of the sampler over a range
of at least ±15 percent of the flow rate specified in section 7.4.1
of this appendix.
7.4.3 Sample flow rate regulation. The sample flow rate
shall be regulated such that for the specified filter, under
section 6.0 of this appendix, at any atmospheric conditions
specified, under section 7.4.7 of this appendix, at a filter
pressure drop equal to that of a clean filter plus up to 75 cm
water column (55 mm Hg), and over the specified range of supply
line voltage, under section 7.4.15.1 of this appendix, the flow
rate is regulated as follows:
7.4.3.1 The volumetric flow rate, measured or averaged over
intervals of not more than 5 minutes over a 24-hour period, shall
not vary more than ±5 percent from the specified 16.67 L/min flow
rate over the entire sample period.
7.4.3.2 The coefficient of variation (sample standard deviation
divided by the mean) of the flow rate, measured over a 24-hour
period, shall not be greater than 2 percent.
7.4.3.3 The amplitude of short-term flow rate pulsations, such
as may originate from some types of vacuum pumps, shall be
attenuated such that they do not cause significant flow measurement
error or affect the collection of particles on the particle
collection filter.
7.4.4 Flow rate cut off. The sampler's sample air flow
rate control system shall terminate sample collection and stop all
sample flow for the remainder of the sample period in the event
that the sample flow rate deviates by more than 10 percent from the
sampler design flow rate specified in section 7.4.1 of this
appendix for more than 60 seconds. However, this sampler cut-off
provision shall not apply during periods when the sampler is
inoperative due to a temporary power interruption, and the elapsed
time of the inoperative period shall not be included in the total
sample time measured and reported by the sampler, under section
7.4.13 of this appendix.
7.4.5 Flow rate measurement.
7.4.5.1 The sampler shall provide a means to measure and
indicate the instantaneous sample air flow rate, which shall be
measured as volumetric flow rate at the temperature and pressure of
the sample air entering the inlet, with an accuracy of ±2 percent.
The measured flow rate shall be available for display to the
sampler operator at any time in either sampling or standby modes,
and the measurement shall be updated at least every 30 seconds. The
sampler shall also provide a simple means by which the sampler
operator can manually start the sample flow temporarily during
non-sampling modes of operation, for the purpose of checking the
sample flow rate or the flow rate measurement system.
7.4.5.2 During each sample period, the sampler's flow rate
measurement system shall automatically monitor the sample
volumetric flow rate, obtaining flow rate measurements at intervals
of not greater than 30 seconds.
(a) Using these interval flow rate measurements, the sampler
shall determine or calculate the following flow-related parameters,
scaled in the specified engineering units:
(1) The instantaneous or interval-average flow rate, in
L/min.
(2) The value of the average sample flow rate for the sample
period, in L/min.
(3) The value of the coefficient of variation (sample standard
deviation divided by the average) of the sample flow rate for the
sample period, in percent.
(4) The occurrence of any time interval during the sample period
in which the measured sample flow rate exceeds a range of ±5
percent of the average flow rate for the sample period for more
than 5 minutes, in which case a warning flag indicator shall be
set.
(5) The value of the integrated total sample volume for the
sample period, in m 3.
(b) Determination or calculation of these values shall properly
exclude periods when the sampler is inoperative due to temporary
interruption of electrical power, under section 7.4.13 of this
appendix, or flow rate cut off, under section 7.4.4 of this
appendix.
(c) These parameters shall be accessible to the sampler operator
as specified in table L-1 of section 7.4.19 of this appendix. In
addition, it is strongly encouraged that the flow rate for each
5-minute interval during the sample period be available to the
operator following the end of the sample period.
7.4.6 Leak test capability.
7.4.6.1 External leakage. The sampler shall include an
external air leak-test capability consisting of components,
accessory hardware, operator interface controls, a written
procedure in the associated Operation/Instruction Manual, under
section 7.4.18 of this appendix, and all other necessary functional
capability to permit and facilitate the sampler operator to
conveniently carry out a leak test of the sampler at a field
monitoring site without additional equipment. The sampler
components to be subjected to this leak test include all components
and their interconnections in which external air leakage would or
could cause an error in the sampler's measurement of the total
volume of sample air that passes through the sample filter.
(a) The suggested technique for the operator to use for this
leak test is as follows:
(1) Remove the sampler inlet and installs the flow rate
measurement adapter supplied with the sampler, under section 7.3.6
of this appendix.
(2) Close the valve on the flow rate measurement adapter and use
the sampler air pump to draw a partial vacuum in the sampler,
including (at least) the impactor, filter holder assembly (filter
in place), flow measurement device, and interconnections between
these devices, of at least 55 mm Hg (75 cm water column), measured
at a location downstream of the filter holder assembly.
(3) Plug the flow system downstream of these components to
isolate the components under vacuum from the pump, such as with a
built-in valve.
(4) Stop the pump.
(5) Measure the trapped vacuum in the sampler with a built-in
pressure measuring device.
(6) (i) Measure the vacuum in the sampler with the built-in
pressure measuring device again at a later time at least 10 minutes
after the first pressure measurement.
(ii) Caution: Following completion of the test, the adaptor
valve should be opened slowly to limit the flow rate of air into
the sampler. Excessive air flow rate may blow oil out of the
impactor.
(7) Upon completion of the test, open the adaptor valve, remove
the adaptor and plugs, and restore the sampler to the normal
operating configuration.
(b) The associated leak test procedure shall require that for
successful passage of this test, the difference between the two
pressure measurements shall not be greater than the number of mm of
Hg specified for the sampler by the manufacturer, based on the
actual internal volume of the sampler, that indicates a leak of
less than 80 mL/min.
(c) Variations of the suggested technique or an alternative
external leak test technique may be required for samplers whose
design or configuration would make the suggested technique
impossible or impractical. The specific proposed external leak test
procedure, or particularly an alternative leak test technique,
proposed for a particular candidate sampler may be described and
submitted to the EPA for specific individual acceptability either
as part of a reference or equivalent method application under part
53 of this chapter or in writing in advance of such an intended
application under part 53 of this chapter.
7.4.6.2 Internal, filter bypass leakage. The sampler
shall include an internal, filter bypass leak-check capability
consisting of components, accessory hardware, operator interface
controls, a written procedure in the Operation/Instruction Manual,
and all other necessary functional capability to permit and
facilitate the sampler operator to conveniently carry out a test
for internal filter bypass leakage in the sampler at a field
monitoring site without additional equipment. The purpose of the
test is to determine that any portion of the sample flow rate that
leaks past the sample filter without passing through the filter is
insignificant relative to the design flow rate for the sampler.
(a) The suggested technique for the operator to use for this
leak test is as follows:
(1) Carry out an external leak test as provided under section
7.4.6.1 of this appendix which indicates successful passage of the
prescribed external leak test.
(2) Install a flow-impervious membrane material in the filter
cassette, either with or without a filter, as appropriate, which
effectively prevents air flow through the filter.
(3) Use the sampler air pump to draw a partial vacuum in the
sampler, downstream of the filter holder assembly, of at least 55
mm Hg (75 cm water column).
(4) Plug the flow system downstream of the filter holder to
isolate the components under vacuum from the pump, such as with a
built-in valve.
(5) Stop the pump.
(6) Measure the trapped vacuum in the sampler with a built-in
pressure measuring device.
(7) Measure the vacuum in the sampler with the built-in pressure
measuring device again at a later time at least 10 minutes after
the first pressure measurement.
(8) Remove the flow plug and membrane and restore the sampler to
the normal operating configuration.
(b) The associated leak test procedure shall require that for
successful passage of this test, the difference between the two
pressure measurements shall not be greater than the number of mm of
Hg specified for the sampler by the manufacturer, based on the
actual internal volume of the portion of the sampler under vacuum,
that indicates a leak of less than 80 mL/min.
(c) Variations of the suggested technique or an alternative
internal, filter bypass leak test technique may be required for
samplers whose design or configuration would make the suggested
technique impossible or impractical. The specific proposed internal
leak test procedure, or particularly an alternative internal leak
test technique proposed for a particular candidate sampler may be
described and submitted to the EPA for specific individual
acceptability either as part of a reference or equivalent method
application under part 53 of this chapter or in writing in advance
of such intended application under part 53 of this chapter.
7.4.7 Range of operational conditions. The sampler is
required to operate properly and meet all requirements specified in
this appendix over the following operational ranges.
7.4.7.1 Ambient temperature. −30 to = 45 °C (Note:
Although for practical reasons, the temperature range over which
samplers are required to be tested under part 53 of this chapter is
−20 to = 40 °C, the sampler shall be designed to operate properly
over this wider temperature range.).
7.4.7.2 Ambient relative humidity. 0 to 100 percent.
7.4.7.3 Barometric pressure range. 600 to 800 mm Hg.
7.4.8 Ambient temperature sensor. The sampler shall have
capability to measure the temperature of the ambient air
surrounding the sampler over the range of −30 to = 45 °C, with a
resolution of 0.1 °C and accuracy of ±2.0 °C, referenced as
described in reference 3 in section 13.0 of this appendix, with and
without maximum solar insolation.
7.4.8.1 The ambient temperature sensor shall be mounted external
to the sampler enclosure and shall have a passive, naturally
ventilated sun shield. The sensor shall be located such that the
entire sun shield is at least 5 cm above the horizontal plane of
the sampler case or enclosure (disregarding the inlet and downtube)
and external to the vertical plane of the nearest side or
protuberance of the sampler case or enclosure. The maximum
temperature measurement error of the ambient temperature
measurement system shall be less than 1.6 °C at 1 m/s wind speed
and 1000 W/m2 solar radiation intensity.
7.4.8.2 The ambient temperature sensor shall be of such a design
and mounted in such a way as to facilitate its convenient
dismounting and immersion in a liquid for calibration and
comparison to the filter temperature sensor, under section 7.4.11
of this appendix.
7.4.8.3 This ambient temperature measurement shall be updated at
least every 30 seconds during both sampling and standby
(non-sampling) modes of operation. A visual indication of the
current (most recent) value of the ambient temperature measurement,
updated at least every 30 seconds, shall be available to the
sampler operator during both sampling and standby (non-sampling)
modes of operation, as specified in table L-1 of section 7.4.19 of
this appendix.
7.4.8.4 This ambient temperature measurement shall be used for
the purpose of monitoring filter temperature deviation from ambient
temperature, as required by section 7.4.11 of this appendix, and
may be used for purposes of effecting filter temperature control,
under section 7.4.10 of this appendix, or computation of volumetric
flow rate, under sections 7.4.1 to 7.4.5 of this appendix, if
appropriate.
7.4.8.5 Following the end of each sample period, the sampler
shall report the maximum, minimum, and average temperature for the
sample period, as specified in table L-1 of section 7.4.19 of this
appendix.
7.4.9 Ambient barometric sensor. The sampler shall have
capability to measure the barometric pressure of the air
surrounding the sampler over a range of 600 to 800 mm Hg referenced
as described in reference 3 in section 13.0 of this appendix; also
see part 53, subpart E of this chapter. This barometric pressure
measurement shall have a resolution of 5 mm Hg and an accuracy of
±10 mm Hg and shall be updated at least every 30 seconds. A visual
indication of the value of the current (most recent) barometric
pressure measurement, updated at least every 30 seconds, shall be
available to the sampler operator during both sampling and standby
(non-sampling) modes of operation, as specified in table L-1 of
section 7.4.19 of this appendix. This barometric pressure
measurement may be used for purposes of computation of volumetric
flow rate, under sections 7.4.1 to 7.4.5 of this appendix, if
appropriate. Following the end of a sample period, the sampler
shall report the maximum, minimum, and mean barometric pressures
for the sample period, as specified in table L-1 of section 7.4.19
of this appendix.
7.4.10 Filter temperature control (sampling and
post-sampling). The sampler shall provide a means to limit the
temperature rise of the sample filter (all sample filters for
sequential samplers), from insolation and other sources, to no more
5 °C above the temperature of the ambient air surrounding the
sampler, during both sampling and post-sampling periods of
operation. The post-sampling period is the non-sampling period
between the end of the active sampling period and the time of
retrieval of the sample filter by the sampler operator.
7.4.11 Filter temperature sensor(s).
7.4.11.1 The sampler shall have the capability to monitor the
temperature of the sample filter (all sample filters for sequential
samplers) over the range of −30 to = 45 °C during both sampling and
non-sampling periods. While the exact location of this temperature
sensor is not explicitly specified, the filter temperature
measurement system must demonstrate agreement, within 1 °C, with a
test temperature sensor located within 1 cm of the center of the
filter downstream of the filter during both sampling and
non-sampling modes, as specified in the filter temperature
measurement test described in part 53, subpart E of this chapter.
This filter temperature measurement shall have a resolution of 0.1
°C and accuracy of ±1.0 °C, referenced as described in reference 3
in section 13.0 of this appendix. This temperature sensor shall be
of such a design and mounted in such a way as to facilitate its
reasonably convenient dismounting and immersion in a liquid for
calibration and comparison to the ambient temperature sensor under
section 7.4.8 of this appendix.
7.4.11.2 The filter temperature measurement shall be updated at
least every 30 seconds during both sampling and standby
(non-sampling) modes of operation. A visual indication of the
current (most recent) value of the filter temperature measurement,
updated at least every 30 seconds, shall be available to the
sampler operator during both sampling and standby (non-sampling)
modes of operation, as specified in table L-1 of section 7.4.19 of
this appendix.
7.4.11.3 For sequential samplers, the temperature of each filter
shall be measured individually unless it can be shown, as specified
in the filter temperature measurement test described in § 53.57 of
this chapter, that the temperature of each filter can be
represented by fewer temperature sensors.
7.4.11.4 The sampler shall also provide a warning flag indicator
following any occurrence in which the filter temperature (any
filter temperature for sequential samplers) exceeds the ambient
temperature by more than 5 °C for more than 30 consecutive minutes
during either the sampling or post-sampling periods of operation,
as specified in table L-1 of section 7.4.19 of this appendix, under
section 10.12 of this appendix, regarding sample validity when a
warning flag occurs. It is further recommended (not required) that
the sampler be capable of recording the maximum differential
between the measured filter temperature and the ambient temperature
and its time and date of occurrence during both sampling and
post-sampling (non-sampling) modes of operation and providing for
those data to be accessible to the sampler operator following the
end of the sample period, as suggested in table L-1 of section
7.4.19 of this appendix.
7.4.12 Clock/timer system.
(a) The sampler shall have a programmable real-time clock
timing/control system that:
(1) Is capable of maintaining local time and date, including
year, month, day-of-month, hour, minute, and second to an accuracy
of ±1.0 minute per month.
(2) Provides a visual indication of the current system time,
including year, month, day-of-month, hour, and minute, updated at
least each minute, for operator verification.
(3) Provides appropriate operator controls for setting the
correct local time and date.
(4) Is capable of starting the sample collection period and
sample air flow at a specific, operator-settable time and date, and
stopping the sample air flow and terminating the sampler collection
period 24 hours (1440 minutes) later, or at a specific,
operator-settable time and date.
(b) These start and stop times shall be readily settable by the
sampler operator to within ±1.0 minute. The system shall provide a
visual indication of the current start and stop time settings,
readable to ±1.0 minute, for verification by the operator, and the
start and stop times shall also be available via the data output
port, as specified in table L-1 of section 7.4.19 of this appendix.
Upon execution of a programmed sample period start, the sampler
shall automatically reset all sample period information and warning
flag indications pertaining to a previous sample period. Refer also
to section 7.4.15.4 of this appendix regarding retention of current
date and time and programmed start and stop times during a
temporary electrical power interruption.
7.4.13 Sample time determination. The sampler shall be
capable of determining the elapsed sample collection time for each
PM2.5 sample, accurate to within ±1.0 minute, measured as the time
between the start of the sampling period, under section 7.4.12 of
this appendix and the termination of the sample period, under
section 7.4.12 of this appendix or section 7.4.4 of this appendix.
This elapsed sample time shall not include periods when the sampler
is inoperative due to a temporary interruption of electrical power,
under section 7.4.15.4 of this appendix. In the event that the
elapsed sample time determined for the sample period is not within
the range specified for the required sample period in section 3.3
of this appendix, the sampler shall set a warning flag indicator.
The date and time of the start of the sample period, the value of
the elapsed sample time for the sample period, and the flag
indicator status shall be available to the sampler operator
following the end of the sample period, as specified in table L-1
of section 7.4.19 of this appendix.
7.4.14 Outdoor environmental enclosure. The sampler shall
have an outdoor enclosure (or enclosures) suitable to protect the
filter and other non-weatherproof components of the sampler from
precipitation, wind, dust, extremes of temperature and humidity; to
help maintain temperature control of the filter (or filters, for
sequential samplers); and to provide reasonable security for
sampler components and settings.
7.4.15 Electrical power supply.
7.4.15.1 The sampler shall be operable and function as specified
herein when operated on an electrical power supply voltage of 105
to 125 volts AC (RMS) at a frequency of 59 to 61 Hz. Optional
operation as specified at additional power supply voltages and/or
frequencies shall not be precluded by this requirement.
7.4.15.2 The design and construction of the sampler shall comply
with all applicable National Electrical Code and Underwriters
Laboratories electrical safety requirements.
7.4.15.3 The design of all electrical and electronic controls
shall be such as to provide reasonable resistance to interference
or malfunction from ordinary or typical levels of stray
electromagnetic fields (EMF) as may be found at various monitoring
sites and from typical levels of electrical transients or
electronic noise as may often or occasionally be present on various
electrical power lines.
7.4.15.4 In the event of temporary loss of electrical supply
power to the sampler, the sampler shall not be required to sample
or provide other specified functions during such loss of power,
except that the internal clock/timer system shall maintain its
local time and date setting within ±1 minute per week, and the
sampler shall retain all other time and programmable settings and
all data required to be available to the sampler operator following
each sample period for at least 7 days without electrical supply
power. When electrical power is absent at the operator-set time for
starting a sample period or is interrupted during a sample period,
the sampler shall automatically start or resume sampling when
electrical power is restored, if such restoration of power occurs
before the operator-set stop time for the sample period.
7.4.15.5 The sampler shall have the capability to record and
retain a record of the year, month, day-of-month, hour, and minute
of the start of each power interruption of more than 1 minute
duration, up to 10 such power interruptions per sample period.
(More than 10 such power interruptions shall invalidate the sample,
except where an exceedance is measured, under section 3.3 of this
appendix.) The sampler shall provide for these power interruption
data to be available to the sampler operator following the end of
the sample period, as specified in table L-1 of section 7.4.19 of
this appendix.
7.4.16 Control devices and operator interface. The
sampler shall have mechanical, electrical, or electronic controls,
control devices, electrical or electronic circuits as necessary to
provide the timing, flow rate measurement and control, temperature
control, data storage and computation, operator interface, and
other functions specified. Operator-accessible controls, data
displays, and interface devices shall be designed to be simple,
straightforward, reliable, and easy to learn, read, and operate
under field conditions. The sampler shall have provision for
operator input and storage of up to 64 characters of numeric (or
alphanumeric) data for purposes of site, sampler, and sample
identification. This information shall be available to the sampler
operator for verification and change and for output via the data
output port along with other data following the end of a sample
period, as specified in table L-1 of section 7.4.19 of this
appendix. All data required to be available to the operator
following a sample collection period or obtained during standby
mode in a post-sampling period shall be retained by the sampler
until reset, either manually by the operator or automatically by
the sampler upon initiation of a new sample collection period.
7.4.17 Data output port requirement. The sampler shall
have a standard RS-232C data output connection through which
digital data may be exported to an external data storage or
transmission device. All information which is required to be
available at the end of each sample period shall be accessible
through this data output connection. The information that shall be
accessible though this output port is summarized in table L-1 of
section 7.4.19 of this appendix. Since no specific format for the
output data is provided, the sampler manufacturer or vendor shall
make available to sampler purchasers appropriate computer software
capable of receiving exported sampler data and correctly
translating the data into a standard spreadsheet format and
optionally any other formats as may be useful to sampler users.
This requirement shall not preclude the sampler from offering other
types of output connections in addition to the required RS-232C
port.
7.4.18 Operation/instruction manual. The sampler shall
include an associated comprehensive operation or instruction
manual, as required by part 53 of this chapter, which includes
detailed operating instructions on the setup, operation,
calibration, and maintenance of the sampler. This manual shall
provide complete and detailed descriptions of the operational and
calibration procedures prescribed for field use of the sampler and
all instruments utilized as part of this reference method. The
manual shall include adequate warning of potential safety hazards
that may result from normal use or malfunction of the method and a
description of necessary safety precautions. The manual shall also
include a clear description of all procedures pertaining to
installation, operation, periodic and corrective maintenance, and
troubleshooting, and shall include parts identification
diagrams.
7.4.19 Data reporting requirements. The various
information that the sampler is required to provide and how it is
to be provided is summarized in the following table L-1.
Table L-1 to Appendix L of Part 50 -
Summary of Information To Be Provided by the Sampler
Information to be
provided |
Appendix L
section
reference |
Availability |
Format |
Anytime 1 |
End of
period 2 |
Visual
display 3 |
Data
output 4 |
Digital
reading 5 |
Units |
Flow rate,
30-second maximum interval |
7.4.5.1 |
✓ |
|
✓ |
* |
XX.X |
L/min |
Flow rate, average
for the sample period |
7.4.5.2 |
* |
✓ |
* |
✓ |
XX.X |
L/min |
Flow rate, CV, for
sample period |
7.4.5.2 |
* |
✓ |
* |
✓ |
XX.X |
% |
Flow rate, 5-min.
average out of spec. (FLAG 6) |
7.4.5.2 |
✓ |
✓ |
✓ |
✓▪ |
On/Off |
|
Sample volume,
total |
7.4.5.2 |
* |
✓ |
✓ |
✓ |
XX.X |
m 3 |
Temperature,
ambient, 30-second interval |
7.4.8 |
✓ |
|
✓ |
|
XX.X |
°C |
Temperature,
ambient, min., max., average for the sample period |
7.4.8 |
* |
✓ |
✓ |
✓▪ |
XX.X |
°C |
Baro. pressure,
ambient, 30-second interval |
7.4.9 |
✓ |
|
✓ |
|
XXX |
mm Hg |
Baro. pressure,
ambient, min., max., average for the sample period |
7.4.9 |
* |
✓ |
✓ |
✓▪ |
XXX |
mm Hg |
Filter
temperature, 30-second interval |
7.4.11 |
✓ |
|
✓ |
|
XX.X |
°C |
Filter temp.
differential, 30-second interval, out of spec. (FLAG
6) |
7.4.11 |
* |
✓ |
✓ |
✓▪ |
On/Off |
|
Filter temp.,
maximum differential from ambient, date, time of occurrence |
7.4.11 |
* |
* |
* |
* |
X.X, YY/MM/DD HH.mm |
°C, Yr/Mon/Day Hrs. min |
Date and Time |
7.4.12 |
✓ |
|
✓ |
|
YY/MM/DD HH.mm |
Yr/Mon/Day Hrs. min |
Sample start and
stop time settings |
7.4.12 |
✓ |
✓ |
✓ |
✓ |
YY/MM/DD HH.mm |
Yr/Mon/Day Hrs. min |
Sample period
start time |
7.4.12 |
|
✓ |
✓ |
✓ |
YY/MM/DD HH.mm |
Yr/Mon/Day Hrs. min |
Elapsed sample
time |
7.4.13 |
* |
✓ |
✓ |
✓ |
HH.mm |
Hrs. min |
Elapsed sample
time, out of spec. (FLAG 6) |
7.4.13 |
|
✓ |
✓ |
✓▪ |
On/Off |
|
Power
interruptions ≤1 min., start time of first 10 |
7.4.15.5 |
* |
✓ |
* |
✓ |
1HH.mm, 2HH.mm, etc. |
Hrs. min |
User-entered
information, such as sampler and site identification |
7.4.16 |
✓ |
✓ |
✓ |
✓▪ |
As entered |
|
8.0 Filter Weighing. See reference 2 in section 13.0 of
this appendix, for additional, more detailed guidance.
8.1 Analytical balance. The analytical balance used to
weigh filters must be suitable for weighing the type and size of
filters specified, under section 6.0 of this appendix, and have a
readability of ±1 µg. The balance shall be calibrated as specified
by the manufacturer at installation and recalibrated immediately
prior to each weighing session. See reference 2 in section 13.0 of
this appendix for additional guidance.
8.2 Filter conditioning. All sample filters used shall be
conditioned immediately before both the pre- and post-sampling
weighings as specified below. See reference 2 in section 13.0 of
this appendix for additional guidance.
8.2.1 Mean temperature. 20 - 23 °C.
8.2.2 Temperature control. ±2 °C over 24 hours.
8.2.3 Mean humidity. Generally, 30-40 percent relative
humidity; however, where it can be shown that the mean ambient
relative humidity during sampling is less than 30 percent,
conditioning is permissible at a mean relative humidity within ±5
relative humidity percent of the mean ambient relative humidity
during sampling, but not less than 20 percent.
8.2.4 Humidity control. ±5 relative humidity percent over
24 hours.
8.2.5 Conditioning time. Not less than 24 hours.
8.3 Weighing procedure.
8.3.1 New filters should be placed in the conditioning
environment immediately upon arrival and stored there until the
pre-sampling weighing. See reference 2 in section 13.0 of this
appendix for additional guidance.
8.3.2 The analytical balance shall be located in the same
controlled environment in which the filters are conditioned. The
filters shall be weighed immediately following the conditioning
period without intermediate or transient exposure to other
conditions or environments.
8.3.3 Filters must be conditioned at the same conditions
(humidity within ±5 relative humidity percent) before both the pre-
and post-sampling weighings.
8.3.4 Both the pre- and post-sampling weighings should be
carried out on the same analytical balance, using an effective
technique to neutralize static charges on the filter, under
reference 2 in section 13.0 of this appendix. If possible, both
weighings should be carried out by the same analyst.
8.3.5 The pre-sampling (tare) weighing shall be within 30 days
of the sampling period.
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 °C or
below for average sampling temperatures less than 4 °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.
8.3.7 Filter blanks.
8.3.7.1 New field blank filters shall be weighed along with the
pre-sampling (tare) weighing of each lot of PM2.5 filters. These
blank filters shall be transported to the sampling site, installed
in the sampler, retrieved from the sampler without sampling, and
reweighed as a quality control check.
8.3.7.2 New laboratory blank filters shall be weighed along with
the pre-sampling (tare) weighing of each set of PM2.5 filters.
These laboratory blank filters should remain in the laboratory in
protective containers during the field sampling and should be
reweighed as a quality control check.
8.3.8 Additional guidance for proper filter weighing and related
quality assurance activities is provided in reference 2 in section
13.0 of this appendix.
9.0 Calibration. Reference 2 in section 13.0 of this
appendix contains additional guidance.
9.1 General requirements.
9.1.1 Multipoint calibration and single-point verification of
the sampler's flow rate measurement device must be performed
periodically to establish and maintain traceability of subsequent
flow measurements to a flow rate standard.
9.1.2 An authoritative flow rate standard shall be used for
calibrating or verifying the sampler's flow rate measurement device
with an accuracy of ±2 percent. The flow rate standard shall be a
separate, stand-alone device designed to connect to the flow rate
measurement adapter, Figure L-30 of this appendix. This flow rate
standard must have its own certification and be traceable to a
National Institute of Standards and Technology (NIST) primary
standard for volume or flow rate. If adjustments to the sampler's
flow rate measurement system calibration are to be made in
conjunction with an audit of the sampler's flow measurement system,
such adjustments shall be made following the audit. Reference 2 in
section 13.0 of this appendix contains additional guidance.
9.1.3 The sampler's flow rate measurement device shall be
re-calibrated after electromechanical maintenance or transport of
the sampler.
9.2 Flow rate calibration/verification procedure.
9.2.1 PM2.5 samplers may employ various types of flow control
and flow measurement devices. The specific procedure used for
calibration or verification of the flow rate measurement device
will vary depending on the type of flow rate controller and flow
rate measurement employed. Calibration shall be in terms of actual
ambient volumetric flow rates (Q a), measured at the sampler's
inlet downtube. The generic procedure given here serves to
illustrate the general steps involved in the calibration of a PM2.5
sampler. The sampler operation/instruction manual required under
section 7.4.18 of this appendix and the Quality Assurance Handbook
in reference 2 in section 13.0 of this appendix provide more
specific and detailed guidance for calibration.
9.2.2 The flow rate standard used for flow rate calibration
shall have its own certification and be traceable to a NIST primary
standard for volume or flow rate. A calibration relationship for
the flow rate standard, e.g., an equation, curve, or family of
curves relating actual flow rate (Qa) to the flow rate indicator
reading, shall be established that is accurate to within 2 percent
over the expected range of ambient temperatures and pressures at
which the flow rate standard may be used. The flow rate standard
must be re-calibrated or re-verified at least annually.
9.2.3 The sampler flow rate measurement device shall be
calibrated or verified by removing the sampler inlet and connecting
the flow rate standard to the sampler's downtube in accordance with
the operation/instruction manual, such that the flow rate standard
accurately measures the sampler's flow rate. The sampler operator
shall first carry out a sampler leak check and confirm that the
sampler passes the leak test and then verify that no leaks exist
between the flow rate standard and the sampler.
9.2.4 The calibration relationship between the flow rate (in
actual L/min) indicated by the flow rate standard and by the
sampler's flow rate measurement device shall be established or
verified in accordance with the sampler operation/instruction
manual. Temperature and pressure corrections to the flow rate
indicated by the flow rate standard may be required for certain
types of flow rate standards. Calibration of the sampler's flow
rate measurement device shall consist of at least three separate
flow rate measurements (multipoint calibration) evenly spaced
within the range of −10 percent to = 10 percent of the sampler's
operational flow rate, section 7.4.1 of this appendix. Verification
of the sampler's flow rate shall consist of one flow rate
measurement at the sampler's operational flow rate. The sampler
operation/instruction manual and reference 2 in section 13.0 of
this appendix provide additional guidance.
9.2.5 If during a flow rate verification the reading of the
sampler's flow rate indicator or measurement device differs by ±4
percent or more from the flow rate measured by the flow rate
standard, a new multipoint calibration shall be performed and the
flow rate verification must then be repeated.
9.2.6 Following the calibration or verification, the flow rate
standard shall be removed from the sampler and the sampler inlet
shall be reinstalled. Then the sampler's normal operating flow rate
(in L/min) shall be determined with a clean filter in place. If the
flow rate indicated by the sampler differs by ±2 percent or more
from the required sampler flow rate, the sampler flow rate must be
adjusted to the required flow rate, under section 7.4.1 of this
appendix.
9.3 Periodic calibration or verification of the calibration of
the sampler's ambient temperature, filter temperature, and
barometric pressure measurement systems is also required. Reference
3 of section 13.0 of this appendix contains additional
guidance.
10.0 PM2.5 Measurement Procedure. The detailed
procedure for obtaining valid PM2.5 measurements with each specific
sampler designated as part of a reference method for PM2.5 under
part 53 of this chapter shall be provided in the sampler-specific
operation or instruction manual required by section 7.4.18 of this
appendix. Supplemental guidance is provided in section 2.12 of the
Quality Assurance Handbook listed in reference 2 in section 13.0 of
this appendix. The generic procedure given here serves to
illustrate the general steps involved in the PM2.5 sample
collection and measurement, using a PM2.5 reference method
sampler.
10.1 The sampler shall be set up, calibrated, and operated in
accordance with the specific, detailed guidance provided in the
specific sampler's operation or instruction manual and in
accordance with a specific quality assurance program developed and
established by the user, based on applicable supplementary guidance
provided in reference 2 in section 13.0 of this appendix.
10.2 Each new sample filter shall be inspected for correct type
and size and for pinholes, particles, and other imperfections.
Unacceptable filters should be discarded. A unique identification
number shall be assigned to each filter, and an information record
shall be established for each filter. If the filter identification
number is not or cannot be marked directly on the filter,
alternative means, such as a number-identified storage container,
must be established to maintain positive filter identification.
10.3 Each filter shall be conditioned in the conditioning
environment in accordance with the requirements specified in
section 8.2 of this appendix.
10.4 Following conditioning, each filter shall be weighed in
accordance with the requirements specified in section 8.0 of this
appendix and the presampling weight recorded with the filter
identification number.
10.5 A numbered and preweighed filter shall be installed in the
sampler following the instructions provided in the sampler
operation or instruction manual.
10.6 The sampler shall be checked and prepared for sample
collection in accordance with instructions provided in the sampler
operation or instruction manual and with the specific quality
assurance program established for the sampler by the user.
10.7 The sampler's timer shall be set to start the sample
collection at the beginning of the desired sample period and stop
the sample collection 24 hours later.
10.8 Information related to the sample collection (site location
or identification number, sample date, filter identification
number, and sampler model and serial number) shall be recorded and,
if appropriate, entered into the sampler.
10.9 The sampler shall be allowed to collect the PM2.5 sample
during the set 24-hour time period.
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. The protective container shall contain no
loose material that could be transferred to the filter. The
protective container shall hold the filter cassette securely such
that the cover shall not come in contact with the filter's
surfaces. Reference 2 in section 13.0 of this appendix contains
additional information.
10.11 The total sample volume in actual m 3 for the sampling
period and the elapsed sample time shall be obtained from the
sampler and recorded in accordance with the instructions provided
in the sampler operation or instruction manual. All sampler warning
flag indications and other information required by the local
quality assurance program shall also be recorded.
10.12 All factors related to the validity or representativeness
of the sample, such as sampler tampering or malfunctions, unusual
meteorological conditions, construction activity, fires or dust
storms, etc. shall be recorded as required by the local quality
assurance program. The occurrence of a flag warning during a sample
period shall not necessarily indicate an invalid sample but rather
shall indicate the need for specific review of the QC data by a
quality assurance officer to determine sample validity.
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 °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.
10.14. The exposed filter containing the PM2.5 sample shall be
re-conditioned in the conditioning environment in accordance with
the requirements specified in section 8.2 of this appendix.
10.15. The filter shall be reweighed immediately after
conditioning in accordance with the requirements specified in
section 8.0 of this appendix, and the postsampling weight shall be
recorded with the filter identification number.
10.16 The PM2.5 concentration shall be calculated as specified
in section 12.0 of this appendix.
11.0 Sampler Maintenance. The sampler shall be maintained
as described by the sampler's manufacturer in the sampler-specific
operation or instruction manual required under section 7.4.18 of
this appendix and in accordance with the specific quality assurance
program developed and established by the user based on applicable
supplementary guidance provided in reference 2 in section 13.0 of
this appendix.
12.0 Calculations
12.1 (a) The PM2.5 concentration is calculated as:
PM2.5 = (Wf − Wi)/Va where: PM2.5 = mass concentration of PM2.5,
µg/m 3; Wf, Wi = final and initial weights, respectively, of the
filter used to collect the PM2.5 particle sample, µg; Va = total
air volume sampled in actual volume units, as provided by the
sampler, m 3. Note:
Total sample time must be between 1,380 and 1,500 minutes (23
and 25 hrs) for a fully valid PM2.5 sample; however, see also
section 3.3 of this appendix.
13.0 References.
1. Quality Assurance Handbook for Air Pollution Measurement
Systems, Volume I, Principles. EPA/600/R-94/038a, April 1994.
Available from CERI, ORD Publications, U.S. Environmental
Protection Agency, 26 West Martin Luther King Drive, Cincinnati,
Ohio 45268.
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.
3. Quality Assurance Handbook for Air Pollution Measurement
Systems, Volume IV: Meteorological Measurements, (Revised Edition)
EPA/600/R-94/038d, March, 1995. Available from CERI, ORD
Publications, U.S. Environmental Protection Agency, 26 West Martin
Luther King Drive, Cincinnati, Ohio 45268.
4. Military standard specification (mil. spec.) 8625F, Type II,
Class 1 as listed in Department of Defense Index of Specifications
and Standards (DODISS), available from DODSSP-Customer Service,
Standardization Documents Order Desk, 700 Robbins Avenue, Building
4D, Philadelphia, PA 1911-5094.
14.0 Figures L-1 through L-30 to Appendix L.
[62 FR 38714, July
18, 1997, as amended at 64 FR 19719, Apr. 22, 1999; 71 FR 61226,
Oct. 17, 2006]