EPA/600/R-15/011S
February 2014
THE ENVIRONMENTAL TECHNOLOGY VERIFICATION
PROGRAM
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ETV Joint Verification Statement
TECHNOLOGY TYPE: BLACK CARBON MONITORS
APPLICATION: MEASUREMENT OF BLACK CARBON IN AMBIENT
AIR
TECHNOLOGY NAME: Model AE33 Aethalometer
COMPANY: Magee Scientific Corporation
(Manufactured by Aerosol d.o.o., Ljubljana, Slovenia)
ADDRESS: 1916a M. L. King Jr. Way PHONE: (510) 845-2801
Berkeley, CA 94704 FAX: (510) 845-7137
WEB SITE: http://www.mageescientific.com/
The U.S. Environmental Protection Agency (EPA) has established the Environmental Technology Verification
(ETV) Program to facilitate the deployment of innovative or improved environmental technologies through
performance verification and dissemination of information. The goal of the ETV Program is to further
environmental protection by accelerating the acceptance and use of improved and cost-effective technologies.
ETV seeks to achieve this goal by providing high-quality, peer-reviewed data on technology performance to
those involved in the design, distribution, financing, permitting, purchase, and use of environmental
technologies. Information and ETV documents are available at www.epa.gov/etv.
ETV works in partnership with recognized standards and testing organizations, with stakeholder groups
(consisting of buyers, vendor organizations, and permitters), and with individual technology developers. The
program evaluates the performance of innovative technologies by developing test plans that are responsive to
the needs of stakeholders, conducting field or laboratory tests (as appropriate), collecting and analyzing data,
and preparing peer-reviewed reports. All evaluations are conducted in accordance with rigorous quality
assurance (QA) protocols to ensure that data of known and adequate quality are generated and that the results
are defensible.
The Advanced Monitoring Systems (AMS) Center, one of six verification centers under ETV, is operated by
Battelle in cooperation with EPA's National Risk Management Research Laboratory. The AMS Center
evaluated the performance of monitors for determining black carbon concentrations in ambient air. This
verification statement provides a summary of the test results for the Magee Scientific Corporation Model AE33
Aethalometer.
VERIFICATION TEST DESCRIPTION
The verification test was conducted over a period of approximately 30 days (April 5 to May 7, 2013) and
involved the continuous operation of duplicate Model AE33 Aethalometer at the Battelle Columbus Operations
Special Support Site (BCS3) in Columbus, Ohio. Duplicate reference samples were collected over 12-hour
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sampling intervals throughout the testing period, from approximately 7:00 am to 7:00 pm and from approximately
7:00 pm to 7:00 am daily. The reference samples were collected and analyzed by Desert Research Institute for
organic carbon (OC) and elemental carbon (EC) using the Interagency Monitoring of PROtected Visual
Environments (IMPROVE) thermal/optical reflectance (TOR) and thermal/optical transmittance (TOT) protocols.
Note that in this report the filter samples will be referred to as "reference samples." However, it should be noted
that the IMPROVE method is not a true Reference Method in that it is not recognized as an absolute standard.
Nonetheless, it is used within the IMPROVE network as the standard method for EC analysis. Thus the method
was used in this test as an analytical technique used for comparison to the BC monitors. Other thermal/optical
reference methods such as the NIOSH 5040 method may result in different results. The comparability and
correlation of the monitoring technology was determined through comparisons to the collocated reference method
samples. The precision of the Model AE33 Aethalometers was determined from comparisons of paired data from
the duplicate units (identified as "SN089" and "SN090"). Other performance parameters such as data
completeness, maintenance requirements, ease of use, and consumable use were assessed from observations by
the Battelle field testing staff. This test was not intended to simulate long-term performance of analyzers at a
monitoring site.
QA oversight of verification testing was provided by Battelle and EPA. Battelle technical staff conducted a
performance evaluation audit and Battelle QA staff conducted a technical systems audit and a data quality audit of
10% of the test data. This verification statement, the full report on which it is based, and the test/QA plan for this
verification test are all available at www.epa.gov/etv/centers/centerl.html.
TECHNOLOGY DESCRIPTION
The following description of the Model AE33 Aethalometer is based on information provided by the vendor.
This technology description was not verified in this test.
The Aethalometer™ is used for the real-time measurement of optically-absorbing 'Black' or 'Elemental' carbon
aerosol particles. The name "Aethalometer" is derived from the classical Greek verb 'aethaloun' (as9otA,ouv),
meaning 'to blacken with soot'. It was conceptualized in 1979, commercialized in 1986, and has been under
continuous development since that date. The Aethalometer Model AE31 was tested by the ETV Program in
2001. The Model AE33 Aethalometer was released in 2012, and incorporates many scientific and technical
improvements relative to earlier models.
The Aethalometer uses a continuous filtration and optical measurement method to provide a continuous readout
of real-time data for the concentration of 'BC', which is fundamentally defined by 'blackness', an optical
measurement. The optical analysis for BC is designed to be consistent and reproducible, and may be validated
by the use of Neutral Density optical standards.
The AE-33 performs optical analysis at seven discrete wavelengths from 370 nm to 950 nm. These data can be
interpreted in terms of source apportionment, due to the different spectral characteristics of diesel particulates
versus biomass-burning smoke. Aethalometers provide fully automatic, unattended operation. The sample is
collected and analyzed as a spot on a roll of filter tape: depending on location, one roll of tape may last from
months to years. No other consumables are required. The instrument requires no calibration other than periodic
checks of the air flow sensor response.
In recent years, it became apparent that under certain conditions, at certain locations, filter-based optical
measurement techniques can be influenced by a saturation effect (also known as the "loading effect") of variable
magnitude. This effect, when present, can change the reported data by up to a factor of 2 or more, depending on
the nature of the aerosol and the settings of the instrument. At other locations, or at the same location under
conditions of different aerosol climatology, the effect may be reduced or completely absent. The fact that the
"loading effect" is variable and clearly dependent on some attribute of the aerosol indicates that it is a
combination of some aspect of the instrumental method, together with an actual chemical or microphysical
aspect of the aerosol. However, the "loading effect" is always found to be linear with respect to the light
attenuation measured on the filter spot. The Model AE33 Aethalometer corrects for the "loading effect" by
collecting two aerosol spots in parallel, but at rates of accumulation that differ by a factor of two. Mathematical
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combination of the data from the two parallel analyses permits reconstruction of the "ideal" result, together with
a report of the "loading compensation parameter" which may be informative of aerosol properties in its own
right.
VERIFICATION RESULTS
Comparability-
Regression analysis Analyzer
comparison to SN089
reference samples SN090
Comparability- Calculation of Relat
Difference (RPD) between Aethalom
reference method results
TOR
Slope
1.277(0.064)
1.350(0.066)
ive Percent
eter results and
Correlation - Regression analysis comparison to
reference samples
Precision - Comparison of results
monitoring systems
Precision - Regression analysis of
results from duplicate monitoring
systems
Data Completeness
Maintenance
Consumables/waste
generated
Ease of use
Analyzer
SNO*
SNO<
from duplicate
a
Period
1-hour
12-hour
Period
1 -minute
12-hour
1 -minute
12-hour
Intercept
0.286 (0.041)
0.309 (0.042)
Analyzer
SN089
SN090
Analyzer
SN089
SN090
1-hour
12-hour
Slope
1.063 (0.004)
1.051 (0.012)
Total Periods
45,360
63
45,360
63
TOT
Slope
1.701 (0.072)
1.795 (0.076)
Intercept
0.305 (0.034)
0.330(0.036)
RPDa
TOR
95.6%
(N=39)
105.9%
(N=39)
2
r
TOR
0.875
0.880
TOT
149.7%
(N=26)
163.7%
(N=26)
TOT
0.906
0.908
RPD (# of Observations)
8.5%(N=756)
7.1%(N=63)
Intercept
(Hg/m3)
-0.000 (0.005)
0.010(0.012)
Valid
Measurements
45,157
63
45,149
63
r2
0.990
0.992
%
Complete
99.6%
100%
99.5%
100%
• Default instrument settings restored from internal memory card twice
during testing.
• No routine maintenance performed during testing.
• Filter tape required.
• Installation of two units without inlets completed in ~5 minutes.
• Installation of inlets and sampling lines completed in -10 minutes
• Calibration of flow rates completed in less thanSO minutes, after allowing the
units to operate overnight.
• Routine operation required no effort other than brief daily instrument checks
and approximately weekly data downloads.
• Data exported as csv files and processed using Microsoft Excel.
1 For these calculations, reference method results below twice the method detection limit were excluded. For perfect agreement
between the Aethalometers and the reference method results, the RPD would be zero. In general, the measured concentrations
from the Aethalometers were approximately twice as high as those from the reference method resulting in positive RPD values. It
should be noted that only about two thirds of the TOR reference method results and fewer than half the TOT reference method
results were above twice the detection limit.
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Signed by Spencer Pugh 2/28/14 Signed by Cynthia Sonich-Mullin 3/3/14
Spencer Pugh Date Cynthia Sonich-Mullin Date
General Manager Director
Energy & Environment Business Unit National Risk Management Research Laboratory
Energy, Health & Environment Office of Research and Development
Battelle U.S. Environmental Protection Agency
NOTICE: ETV verifications are based on an evaluation of technology performance under specific,
predetermined criteria and the appropriate quality assurance procedures. EPA and Battelle make no expressed or
implied warranties as to the performance of the technology and do not certify that a technology will always
operate as verified. The end user is solely responsible for complying with any and all applicable federal, state,
and local requirements. Mention of commercial product names does not imply endorsement.
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